Co-reporter:Zaizhe Cheng, Shouying Huang, Ying Li, Jing Lv, Kai Cai, and Xinbin Ma
Industrial & Engineering Chemistry Research November 22, 2017 Volume 56(Issue 46) pp:13618-13618
Publication Date(Web):October 23, 2017
DOI:10.1021/acs.iecr.7b03500
The carbonylation of dimethyl ether (DME) to methyl acetate (MA) is one of the crucial steps in an indirect synthesis route of ethanol from syngas (CO+H2). The H-MOR zeolite exhibits excellent activity and selectivity at mild conditions. However, the catalyst suffers rapid deactivation due to the carbonaceous deposits on Brønsted acid sites. In this study, the deactivation kinetics for the carbonylation of DME to MA on the H-MOR zeolite was investigated. Based on the fitting results and in situ FTIR analysis, a model taking into account the composition concentration was established. This deactivation kinetic model allows simulating the concentration of different compounds in the reaction medium with time on stream under different experimental conditions. In this model, coke is considered to be derived from DME and CO. Moreover, CO remarkably accelerates the coke formation, and the effect of its concentration on the deactivation rate is quantified. The establishment of deactivation kinetics will be conductive to elucidate the coke formation mechanism and optimize the process conditions.
Co-reporter:Jing Lv;Yu-jun Zhao;Xin-bin Ma;Yan Xu;Zhen-hua Li;Qu Chen
Industrial & Engineering Chemistry Research March 19, 2014 Volume 53(Issue 11) pp:4207-4214
Publication Date(Web):2017-2-22
DOI:10.1021/ie404253x
The autocatalytic hydrolysis kinetics of dimethyl oxalate (DMO) was investigated in an isothermal batch reactor at 328.15–358.15 K. It was observed that DMO hydrolysis involved two reactions in series, with monomethyl oxalate (MMO) as an intermediate product. The results showed that water dominates the initial hydrolysis rate of DMO. In later stages, oxalic acid plays a major role in catalyzing DMO hydrolysis and MMO further hydrolysis. Based on these observations, a mechanism involving the ionization of water and oxalic acid was developed that assumes nucleophilic substitution to be the rate-determining step. Concentration-based rate equations were further deduced including the contribution of water startup and the catalytic action of oxalic acid. In addition, the kinetic and equilibrium parameters were estimated from the experimental data through regression analysis.
Co-reporter:Zheng Qu;Ying Li;Shouying Huang;Pengzhen Chen
Science China Chemistry 2017 Volume 60( Issue 7) pp:912-919
Publication Date(Web):06 May 2017
DOI:10.1007/s11426-016-9063-2
In this work, the nature, location and evolution of Cu+ ions in Cu-SAPO-34 are investigated by diffuse reflectance infrared Fourier transform spectrum (DRIFTS) of CO adsorption and density functional theory (DFT) calculation. By combination with DFT results, characteristic Cu+–CO bands located at 2154 and 2136 cm−1 are attributed to CO adsorbed on Cu+ ions located at sites I (in the plane of six-membered ring connected to the large cages) and site II (in the eight-membered ring cages near the tilted four membered ring) in the framework of H-SAPO-34 zeolite. Subsequently, both the influences of Cu loading and preparation method are considered and discussed. By varying the Cu loading, the site-occupation preference of Cu+ ions on site I is confirmed, especially at low Cu loadings. Through elevating the desorption temperature, migration of Cu+ ions is revealed because of the adsorption-induced effect. Furthermore, a facile and more efficient approach to introduce Cu+ ions into CHA zeolite, compared with solid-state ion exchange with CuCl and conventional ion exchange in aqueous solution, and the different preparation methods also result in different occupations of Cu+ ions.
Co-reporter:Dajun Meng, Baowei Wang, Zhen Liu, Weihan Wang, ... Xinbin Ma
Journal of Energy Chemistry 2017 Volume 26, Issue 3(Volume 26, Issue 3) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.jechem.2017.01.006
CeO2 supports were prepared by calcination or precipitation method and 5% MoO3/CeO2 catalysts were prepared by incipient-wetness impregnation method. The catalytic performance of the 5% MoO3/CeO2 catalysts toward sulfur-resistant methanation was investigated. The results showed that the Mo/Ce-1 catalysts with CeO2 support prepared by calcination method exhibited the best sulfur-resistant methanation activity and stability with CO conversion as high as 75% while the Mo/Ce-3 catalysts the poorest. The supports and catalysts were characterized by N2-adsorption–desorption, temperature-programmed reduction (TPR), X-ray diffraction (XRD), Raman spectroscopy (RS) and scanning electron microscope (SEM). The results indicated that the saturated monolayer loading MoO3 on Ce-3 support was lower than 5% and there were some crystalline MoO3 particles on the surface of the Mo/Ce-3. The preparation method of CeO2 had a big influence on the specific surface area, the crystalline of CeO2, and the catalytic performance of the corresponding Mo-based catalyst for sulfur-resistant methanation.CeO2 support was prepared with calcinations and precipitation methods for sulfur-resistant methanation. The conversion of CO is as high as 75% under 1.2% H2S atmosphere on MoO3/CeO2 catalysts whose support is prepared with calcination method.Download high-res image (108KB)Download full-size image
Co-reporter:Yan Xu;Ablikim Meh;Guangcun Yang;Yujun Zhao;Qu Chen;Zhenhua Li
Chemical Engineering & Technology 2016 Volume 39( Issue 5) pp:918-926
Publication Date(Web):
DOI:10.1002/ceat.201500649
Abstract
Catalytic hydrolysis of methyl glycolate is a promising way to produce glycolic acid with high purity. The hydrolysis of methyl glycolate was investigated both in a stirred-batch reactor and in a reactive distillation column. Batch hydrolysis distillation was found to be rather effective in improving the conversion of methyl glycolate. A mechanism model including the cooperative catalysis of sulfuric acid and the generated glycolic acid was developed based on the acid-catalyzed hydrolysis mechanism and the protolysis equilibrium; then, the model was further simplified according to the relationship between the concentrations of hydroxonium ions and their providers. This simplified model could be easily introduced to Aspen Plus and applied to simulating the homogeneous hydrolysis process of methyl glycolate with or without sulfuric acid as catalyst via the reactive distillation technique.
Co-reporter:Shouying Huang, Bing Yan, Shengping Wang and Xinbin Ma
Chemical Society Reviews 2015 vol. 44(Issue 10) pp:3079-3116
Publication Date(Web):20 Mar 2015
DOI:10.1039/C4CS00374H
Dialkyl carbonates are important organic compounds and chemical intermediates with the label of “green chemicals” due to their moderate toxicity, biodegradability for human health and environment. Indeed, owing to their unique physicochemical properties and versatility as reagents, a variety of phosgene-free processes derived from CO or CO2 have been explored for the synthesis of dialkyl carbonates. In this critical review, we highlight the recent achievements (since 1997) in the synthesis of dialkyl carbonates based on CO and CO2 utilization, particularly focusing on the catalyst design and fabrication, structure–function relationship, catalytic mechanisms and process intensification. We also provide an overview regarding the applications of dialkyl carbonates as fuel additives, solvents and reaction intermediates (i.e. alkylating and carbonylating agents). Additionally, this review puts forward the substantial challenges and opportunities for future research associated with dialkyl carbonates.
Co-reporter:Yue Wang, Yongli Shen, Yujun Zhao, Jing Lv, Shengping Wang, and Xinbin Ma
ACS Catalysis 2015 Volume 5(Issue 10) pp:6200
Publication Date(Web):September 14, 2015
DOI:10.1021/acscatal.5b01678
Hydrogenation of carbon–oxygen (C–O) bonds plays a significant role in organic synthesis. Cu-based catalysts have been extensively investigated because of their high selectivity in C–O hydrogenation. However, no consensus has been reached on the precise roles of Cu0 and Cu+ species for C–O hydrogenation reactions. Here we resolve this long-term dispute with a series of highly comparable Cu/SiO2 catalysts. All catalysts represent the full-range distribution of the Cu species and have similar general morphologies, which are detected and mutually corroborated by multiple characterizations. The results demonstrate that, when the accessible metallic Cu surface area is below a certain value, the catalytic activity of hydrogenation linearly increases with increasing Cu0 surface area, whereas it is primarily affected by the Cu+ surface area. Furthermore, the balancing effect of these two active Cu sites on enhancing the catalytic performance is demonstrated: the Cu+ sites adsorb the methoxy and acyl species, while the Cu0 facilitates the H2 decomposition. This insight into the precise roles of active species can lead to new possibilities in the rational design of catalysts for hydrogenation of C–O bonds.Keywords: alcohol; balancing effect; Cu catalyst; Cu0/Cu+ active sites; hydrogenation; methyl acetate
Co-reporter:Huimin Zhan, Shouying Huang, Ying Li, Jing Lv, Shengping Wang and Xinbin Ma
Catalysis Science & Technology 2015 vol. 5(Issue 9) pp:4378-4389
Publication Date(Web):06 May 2015
DOI:10.1039/C5CY00460H
To investigate the role of Cu species in dimethyl ether (DME) carbonylation over Cu/H-MOR catalysts, ion-exchange with copper ammonia solution (Cu/H-M(x)) and solid state ion-exchange with CuCl (SSIE Cu/H-M(x)) methods were applied to prepare a series of samples with different Cu loadings. Compared to H-MOR, the reduced Cu/H-M(x) samples dramatically facilitated the conversion of DME, in which Cu+ and Cu0 species as well as Brønsted acid sites coexisted. Physical adsorption, powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) were carried out to prove the negligible influence of the preparation processes on the textural and morphological properties of MOR. Fourier transform infrared (FTIR) spectroscopy, adsorption of pyridine, CO temperature programmed desorption (CO-TPD), and X-ray photoelectron spectroscopy (XPS) were employed to qualitatively and quantitatively explore the variation of both Brønsted acid sites and Cu species in 8-membered ring (8-MR) and 12-membered ring (12-MR) channels. With an increase of the Cu dopant, the amount of Cu0 increased gradually while Cu+ had no obvious regularity. The relationship between Cu0 and catalyst activity was established for Cu/H-M(x) catalysts. In addition, the formation of methyl acetate (MA) over SSIE Cu/H-M(x) catalysts decreased sharply with increasing Cu+ loading, which further excluded the promoting effect of Cu+ species present in MOR.
Co-reporter:Bao-Wei Wang, Yu-Qin Yao, Si-Han Liu, Zong-Yuan Hu, Zhen-Hua Li, Xin-Bin Ma
Fuel Processing Technology 2015 Volume 138() pp:263-270
Publication Date(Web):October 2015
DOI:10.1016/j.fuproc.2015.06.009
•The monolayer saturated coverage of MoO3 on CeO2 is about 5 wt.%.•CeO2 can be sulfided to Ce2O2S in sulfidation and/or methanation reaction.•Ce2O2S has higher catalytic activity toward sulfur-resistant methanation reaction.•5 wt.% MoO3/CeO2 possesses the best sulfur-resistant methanation performance.•The best calcination temperature of 5 wt.% MoO3/CeO2 is 600 °C.Synthetic natural gas (SNG) production from coal is reconsidered for the rising prices for natural gas and the hope for less dependency on natural gas import and reduction of greenhouse gas CO2 emission. In this paper, the effects of MoO3 loading amounts and calcination temperature on the catalytic performance of MoO3/CeO2 toward sulfur-resistant methanation were investigated. All the catalysts were prepared by incipient-wetness impregnation method and further characterized by N2 adsorption–desorption, temperature-programmed reduction (TPR), X-ray diffraction (XRD) and Raman spectroscopy (RS). The results show that CO conversion reached optimal value when loading 5 wt.% of MoO3 on the CeO2 support. Also, the “monolayer” saturated coverage of MoO3 over the prepared CeO2 support is about 5 wt.%. The MoO3/CeO2 catalyst with MoO3 loading amount of 5 wt.% and calcination temperature of 500 °C exhibits the highest activity for CO conversion.
Co-reporter:Zhenhua Li, Renjie Liu, Yan Xu, Xinbin Ma
Applied Surface Science 2015 Volume 347() pp:643-650
Publication Date(Web):30 August 2015
DOI:10.1016/j.apsusc.2015.04.169
Highlights
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The bamboo-like structure of N-doped CNTs disappeared and the graphitization degree of CNTs was improved after acid treatment.
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More iron species were located inside NCNTs with better iron dispersion after acid treatment.
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Acid treatment of NCNTs enhanced the FTS performance of iron-based catalysts.
Co-reporter:Yuanyuan Dong;Dr. Yongli Shen;Dr. Yujun Zhao;Dr. Shengping Wang ;Dr. Xinbin Ma
ChemCatChem 2015 Volume 7( Issue 16) pp:2460-2466
Publication Date(Web):
DOI:10.1002/cctc.201500317
Abstract
A potassium ion containing Pd/NaY catalyst is introduced that effectively activates the CO molecule for the carbonation of methyl nitrite to synthesize dimethyl carbonate. The potassium ions play a dual role during the activation of CO. Doping the catalyst with potassium enhances the electron density of Pd active species, which strengthens the PdC atoms interaction and thus more strongly activates the CO molecule. Further, the charge-balancing potassium cations in the zeolite interact with the O atom of linear adsorbed carbonyls to form a PdCO⋅⋅⋅K+ structure, which further activates the CO bond. Both experimental analyses and density functional theory calculations indicated that the combination of potassium and Pd species facilitates the activation of CO in the carbonylation reaction.
Co-reporter:Yuanyuan Dong;Dr. Yongli Shen;Dr. Yujun Zhao;Dr. Shengping Wang ;Dr. Xinbin Ma
ChemCatChem 2015 Volume 7( Issue 16) pp:
Publication Date(Web):
DOI:10.1002/cctc.201500765
Abstract
The front cover artwork for Issue 16/2015 is provided by Prof. Xinbin Ma and co-workers from Tianjin University (P.R. China). The image shows the cooperative effect of Pd and K species for the activation of CO in the carbonylation of methyl nitrite to synthesize dimethyl carbonate. See the Full Paper itself at http://dx.doi.org/10.1002/cctc.201500317.
Co-reporter:Yuanyuan Dong;Dr. Yongli Shen;Dr. Yujun Zhao;Dr. Shengping Wang ;Dr. Xinbin Ma
ChemCatChem 2015 Volume 7( Issue 16) pp:
Publication Date(Web):
DOI:10.1002/cctc.201500847
Co-reporter:Pengzhen Chen;Shouying Huang;Jijie Zhang
Frontiers of Chemical Science and Engineering 2015 Volume 9( Issue 2) pp:224-231
Publication Date(Web):2015/06/01
DOI:10.1007/s11705-014-1447-5
CuCl supported on molecular sieves has attracted increasing attention in catalyzing oxidative carbonylation of ethanol to diethyl carbonate. Mesoporous MCM-41 has been widely used as catalyst support due to its large surface area and well defined mesoporous structure. Considering its intrinsic weak acidity, MCM-41 was modified by a simple impregnation method to incorporate Al. The incorporation of Al components resulted in the high dispersion of Cu species and the increase of acid sites without changing the mesoporous structure of MCM-41, and thus enhanceed the catalytic activity of CuCl/MCM-41for diethyl carbonate synthesis.
Co-reporter:Zhenhua Li;Jia He;Haiyang Wang
Frontiers of Chemical Science and Engineering 2015 Volume 9( Issue 1) pp:33-39
Publication Date(Web):2015 March
DOI:10.1007/s11705-014-1446-6
Co-reporter:Shouying Huang, JiJie Zhang, Yue Wang, Pengzhen Chen, Shengping Wang, and Xinbin Ma
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 14) pp:5838-5845
Publication Date(Web):March 6, 2014
DOI:10.1021/ie500288g
Three different methods were used to prepare CuY catalysts, which play an important role in Cu loading and ion-exchange level during the oxidative carbonylation of ethanol to synthesize diethyl carbonate. Of the prepared CuY catalysts, those synthesized by the ammonia evaporation method exhibited a significantly enhanced activity compared to those obtained by the other two methods. In addition, under optimized conditions, four different copper precursors were applied to adjust the textural properties and chemical states of the CuY catalysts. To obtain a deep understanding of their structure–performance relationship, XRD, XPS, CO adsorption, DRIFTS, and NH3 TPD were conducted to characterize the CuY catalysts. The experimental results indicated that the catalytic performances were in line with the proportions of Cu+ in CuY catalysts, which can be regulated by cupric precursors. In addition, the textural structures of the catalysts and the acidity and type of Cu+ species influenced by the precursors were all responsible for the activity and product distribution.
Co-reporter:Bing Yan;Dr. Shouying Huang;Dr. Shengping Wang ;Dr. Xinbin Ma
ChemCatChem 2014 Volume 6( Issue 9) pp:2671-2679
Publication Date(Web):
DOI:10.1002/cctc.201402201
Abstract
Stable catalysts prepared by dispersing Cu2O nanoparticles on activated carbon were investigated in the oxidative carbonylation of methanol to dimethyl carbonate. The effect of the surface oxygen containing groups (OCGs) on the rate of dimethyl carbonate formation and the selectivities of the catalyst for dimethyl carbonate and the byproduct methyl formate were determined. The carbon support surface OCGs played a key role in the oxidative carbonylation. For carbon supports with the same amount of OCGs, the highest catalytic activity was achieved at a certain level of Cu loading. The optimal Cu loading as well as catalytic activity increased linearly with the amount of OCGs. The active sites of the catalysts were the Cu2O nanoparticles that coordinated to the OCGs on the carbon surface.
Co-reporter:Haiyang Wang;Zhenhua Li;Baowei Wang
Korean Journal of Chemical Engineering 2014 Volume 31( Issue 12) pp:2157-2161
Publication Date(Web):2014 December
DOI:10.1007/s11814-014-0170-8
The catalytic activity of Mo-based catalysts prepared from (NH4)6Mo7O24 and (NH4)2MoS4 was compared in the sulfur resistant methanation process. The catalyst using oxide precursor had relatively higher activity than the catalyst using sulfide precursor, and the presulfidation procedure almost had no effect on the catalytic performance of the catalyst using oxide precursor. In view of the characterization results, it could be supposed that the amorphous MoS2 was more active for sulfur-resistant methanation than the crystalline MoS2. The molybdenum sulfides and oxides with lower valence states (Mo4+, Mo5+) could be responsible for the catalytic activity and make a possible contribution to the carbon monoxide methanation in the reaction condition.
Co-reporter:Shengping Wang, Lifang Zhao, Wei Wang, Yujun Zhao, Guanglin Zhang, Xinbin Ma and Jinlong Gong
Nanoscale 2013 vol. 5(Issue 12) pp:5582-5588
Publication Date(Web):22 Apr 2013
DOI:10.1039/C3NR00831B
This paper describes the synthesis of ceria catalysts with octahedron, nanorod, nanocube and spindle-like morphologies via a template-free hydrothermal method. The surface morphologies, crystal plane and physical-chemical structures were investigated via field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and temperature-programmed desorption of ammonia and carbon dioxide (NH3-TPD and CO2-TPD). The catalytic performance over these ceria catalysts with different exposed planes were tested for dimethyl carbonate (DMC) synthesis from CO2 and methanol. The results showed that the spindle-like CeO2 showed the highest DMC yields, followed by nano-rods, nano-cubes and nano-octahedrons. A synergism among the exposed (111) plane, defect sites, and acid-basic sites was proposed to be crucial to obtaining the high reactivity of DMC formation.
Co-reporter:Jinlong Gong, Zhihong Nie and Xinbin Ma
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 29) pp:11985-11987
Publication Date(Web):27 Jun 2013
DOI:10.1039/C3CP90089D
A graphical abstract is available for this content
Co-reporter:Yongli Shen, Qingsen Meng, Shouying Huang, Jinlong Gong and Xinbin Ma
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 31) pp:13116-13127
Publication Date(Web):30 May 2013
DOI:10.1039/C3CP51092A
Density functional theory (DFT) calculations have been used to investigate the oxidative carbonylation of methanol on Pd(II)/β zeolite. Activation energies for all the elementary steps involved in the commonly accepted mechanism, including the formation of dimethyl carbonate, methyl formate and dimethoxymethane, are presented. Upon conducting the calculations, we identify that the Pd2+ cation bonded with four O atoms of the zeolite framework acts as the active site of the catalyst. Molecularly adsorbed methanol starts to react with oxygen molecules to produce a methanediol intermediate (CH2(OH)2) and O atom. Then, another methanol can react with the O atom to produce the (CH3O)(OH)–Pd(II)/β zeolite species. (CH3O)(OH)–Pd(II)/β zeolite can further react with carbon monoxide or methanol to give monomethyl carbonate or di-methoxide species ((CH3O)2–Pd(II)/β zeolite). Dimethyl carbonate can form via two distinct reaction pathways: (I) methanol reacts with monomethyl carbonate or (II) carbon monoxide inserts into di-methoxide. Our calculation results show the activation energy of reaction (I) is too high to be achieved. The methanediol intermediate is unstable and can decompose to formaldehyde and H2O immediately. Formaldehyde can either react with an O atom or methanol to form formic acid or a CH3OCH2OH intermediate. Both of them can react with methanol to form the secondary products (methyl formate or dimethoxymethane). Upon conducting calculations, we confirmed that the activation energies for the formation of methyl formate and dimethoxymethane are higher than that of dimethyl carbonate. All these conformations were characterized at the same calculation level.
Co-reporter:Minhong Jiang, Baowei Wang, Yuqin Yao, Zhenhua Li, Xinbin Ma, Shaodong Qin, Qi Sun
Applied Surface Science 2013 Volume 285(Part B) pp:267-277
Publication Date(Web):15 November 2013
DOI:10.1016/j.apsusc.2013.08.049
Highlights
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A comparative study of CeO2-Al2O3 prepared with different methods is carried out.
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The catalysts whose support is prepared with DP exhibit the best activity.
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CeO2 covered on the surface of support is favorable for the catalytic activity.
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The formation of Al2(MoO4)3 and crystalline MoO3 does not favor the activity.
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CeO2 layer decreases the negative effect of calcination temperature on catalysts.
Co-reporter:Zhenhua Li, Weihan Wang, Jing Lv, and Xinbin Ma
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 8) pp:2814
Publication Date(Web):January 25, 2013
DOI:10.1021/ie302966g
The process of dimethyl oxalate synthesis via CO gaseous phase coupling reaction involves two reactions: CO coupling reaction to produce dimethyl oxalate and the regeneration of methyl nitrite. These two reactions are mutually cycled, and matching reaction rates of both reactions are required. For this purpose, both reactions need to be simulated to provide guidance for scaling up the process. In this paper, the kinetics of methyl nitrite synthesis from NO, NO2, and methanol at atmospheric pressure was obtained by using a stirred reactor. Based on this kinetics equation and mass transfer, a mathematical model for methyl nitrite regeneration reaction from O2, NO, and methanol in a packed bubble column reactor was proposed. Using this model, the effects of reaction temperature, N2 volume fraction, NO/O2 molar ratio, and superficial gas velocity on the methyl nitrite yield were predicted and compared with experimental results. It was found that the model predictions agreed well with experimental data.
Co-reporter:Shouying Huang, Pengzhen Chen, Bing Yan, Shengping Wang, Yongli Shen, and Xinbin Ma
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 19) pp:6349
Publication Date(Web):April 20, 2013
DOI:10.1021/ie3032235
In this work, we modified NaY zeolite (Si/Al = 5) with NaOH solutions of different concentrations followed by ion exchange with NH4NO3 to the H form of the zeolite. Treated NaY was used as a catalyst support for the preparation of CuY for diethyl carbonate (DEC) synthesis through the oxidative carbonylation of ethanol. The textural and acidic properties of NaY and the catalytic performance of the corresponding CuY materials were investigated. Compared with the untreated sample, CuY catalysts using modified NaY samples as supports exhibited higher conversions of ethanol and similar selectivities to DEC. Inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), N2 adsorption, Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM) were used to explore the origin of the improvement in activity. The experimental results showed that alkaline treatment induced defects in the zeolite framework and greatly promoted dealumination through ion exchange assisted by microwave radiation, which caused the generation of meso- and macropores in zeolite Y and contributed to the catalytic performance. Furthermore, the increased amount of hydroxyl species in supercages and extraframework aluminum species resulted in an increase in the number of Cu active sites and further DEC production.
Co-reporter:Zhenhua Li;Haiyang Wang;Erdong Wang;Jing Lv;Yuguang Shang
Kinetics and Catalysis 2013 Volume 54( Issue 3) pp:338-343
Publication Date(Web):2013 May
DOI:10.1134/S0023158413030117
The Co-Mo-Al and Co-Mo-Ce-Al catalysts were prepared and tested for their activity in the methanation of synthesis gas in the presence of hydrogen sulfide. The results showed that the Co-Mo-Ce-Al series was superior to the Co-Mo-Al system in terms of CO conversion. The former system was used to examine the main factors controlling the methanation behavior. Among these are: H2S concentration in the reaction mixture, reaction temperature and pressure, concentrations of CO2, CH4, and H2O, H2/CO ratio, and gaseous hourly space velocity. The methanation activity increased with increasing temperature, pressure and H2/CO ratio. The reason why adding CO2 or H2O decreases the methanation activity is discussed.
Co-reporter:Yuanyuan Dong;Shouying Huang;Dr. Shengping Wang;Dr. Yujun Zhao;Dr. Jinlong Gong ;Dr. Xinbin Ma
ChemCatChem 2013 Volume 5( Issue 8) pp:2174-2177
Publication Date(Web):
DOI:10.1002/cctc.201300170
Co-reporter:Zhenhua Li, Jia Liu, Haiyang Wang, Erdong Wang, Baowei Wang, Xinbin Ma, Shaodong Qin, Qi Sun
Journal of Molecular Catalysis A: Chemical 2013 Volume 378() pp:99-108
Publication Date(Web):1 November 2013
DOI:10.1016/j.molcata.2013.05.019
•The catalysts were prepared using sulfur powder as sulfiding agent.•The optimal sulfidation temperature was 450 °C.•TM-MoS2 was more active because of structural similarity between ATM and MoS2.•The catalyst deactivation was due to the MoS2 crystal growth and structure change.Unsupported MoS2 catalysts were obtained by thermal decomposition of ammonium tetrathiomolybdate (ATM) or ammonium heptamolybdate (AHM) using sulfur powder as sulfiding agent at variable sulfidation temperature (400–550 °C). The CO conversion, selectivity and yield of CH4 on the catalysts were studied for the methanation reaction. It was found that CO conversion increased with temperature rise at first, reached maximum value at sulfidation temperature of 450 °C and then decreased sharply with further increase of temperature. The catalyst derived from ATM could get higher CO conversion than the catalyst from AHM because of the structural similarity between ATM and MoS2. XRD analysis demonstrated that amorphous MoS2 was favorable for the methanation reaction and a crystal transition of MoS2 nanoparticle happened during the methanation reaction. The higher the sulfidation temperature was, the more easily regular crystal structure of MoS2 formed. TEM characterization results showed that at the optimum sulfidation temperature of 450 °C, the length and stacking degree of MoS2 crystallite were the highest and so more active sites could reside on the edges of MoS2 slabs for CO methanation. The crystal growth of MoS2 particle and its structure change are probably the reasons for the deactivation of the MoS2 catalysts with the increase of sulfidation temperature. In addition, it is the loss of surface sulfur that caused deactivation of the catalyst with reaction time.
Co-reporter:Can Lin;Haiyang Wang;Zhenhua Li
Frontiers of Chemical Science and Engineering 2013 Volume 7( Issue 1) pp:88-94
Publication Date(Web):2013 March
DOI:10.1007/s11705-013-1301-1
The effect of adding Co, Ni or La on the methanation activity of a Mo-based sulfur-resistant catalyst was investigated. As promoters, Co, Ni and La all improved the methanation activity of a 15% MoO3/Al2O3 catalyst but to different extents. Similar improvements were also found when Co, Ni or La was added to a 15% MoO3/25%-CeO2-Al2O3 catalyst. The promotion effects of Co and Ni were better than that of La. However, the catalytic methanation activity deteriorated the most with time for the Ni-promoted catalyst. The used catalysts were analyzed by nitrogen adsorption measurement, X-ray diffraction and X-ray photoelectron spectroscopy.
Co-reporter:Jinlong Gong ; Hairong Yue ; Yujun Zhao ; Shuo Zhao ; Li Zhao ; Jing Lv ; Shengping Wang
Journal of the American Chemical Society 2012 Volume 134(Issue 34) pp:13922-13925
Publication Date(Web):May 24, 2012
DOI:10.1021/ja3034153
This paper describes an emerging synthetic route for the production of ethanol (with a yield of ∼83%) via syngas using Cu/SiO2 catalysts. The remarkable stability and efficiency of the catalysts are ascribed to the unique lamellar structure and the cooperative effect between surface Cu0 and Cu+ obtained by an ammonia evaporation hydrothermal method. Characterization results indicated that the Cu0 and Cu+ were formed during the reduction process, originating from well-dispersed CuO and copper phyllosilicate, respectively. A correlation between the catalytic activity and the Cu0 and Cu+ site densities suggested that Cu0 could be the sole active site and primarily responsible for the activity of the catalyst. Moreover, we have shown that the selectivity for ethanol or ethylene glycol can be tuned simply by regulating the reaction temperature.
Co-reporter:Shengping Wang, Yun Shi, and Xinbin Ma
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 16) pp:5737-5742
Publication Date(Web):April 6, 2012
DOI:10.1021/ie202563s
A series of sulfated titanium-submitted mesoporous molecular sieves denoted as S/Ti-MCM-41 were prepared by wet impregnation method with H2SO4 solution as promoter. The results of XRD, N2 adsorption–desorption, NH3-TPD, FTIR of pyridine adsorption, and XPS analysis indicated that S/Ti-MCM-41 samples possess well-ordered hexagonal mesostructure, although the pore diameter and specific surface area shrunk with the increasing coverage of sulfur species. As a result of the electron inductive effect from the S═O bond of SO42–, Lewis acidity is intensified significantly and new Brönsted acid sites are generated from the activated hydroxyl groups. Brönsted acid sites are medium strength, while part of the Lewis acid sites are of weak strength and part of them are medium. The S/Ti-MCM-41 catalysts exhibited desirable activity for transesterification of dimethyl oxalate and phenol.
Co-reporter:Yan Xu, Wenjing Dou, Yujun Zhao, Guangxiao Huang, and Xinbin Ma
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 36) pp:11653-11658
Publication Date(Web):August 8, 2012
DOI:10.1021/ie3004489
The hydrolysis of methyl glycolate catalyzed by commercial cation-exchange resin was studied in a stirred tank batch reactor. It was found that 001×7 resin was an effective catalyst for the hydrolysis of methyl glycolate. The effects of catalyst loading, initial reactant ratio and temperature have been examined in detail. The kinetics of glycolate hydrolysis was evaluated by the use of the pseudohomogeneous model, which was found to represent the kinetics fairly well, due to the total dissociation of the active sulfonic acid group in swollen polymer resin in the presence of water. The kinetics was expressed in terms of activities and the activity coefficients were estimated by using the group contribution method UNIFAC. The activation energy was found to be 59.26 kJ/mol for 001×7 resin, indicating surface reaction is the rate-controlling step.
Co-reporter:Li Zhao, Yujun Zhao, Shengping Wang, Hairong Yue, Bo Wang, Jing Lv, and Xinbin Ma
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 43) pp:13935
Publication Date(Web):October 3, 2012
DOI:10.1021/ie300779a
In this work, the extrusion process of Cu/SiO2 catalysts prepared by the ammonia-evaporation (AE) method has been investigated and optimized in order to obtain materials with convenient catalytic and mechanical properties for their application in the gas-phase hydrogenation reaction of dimethyl oxalate (DMO) to ethylene glycol (EG). Thereby, a variety of Cu/SiO2 extrudates were prepared with different Cu loading. It has been observed that a special microstructure including defects, flaws, and discontinuities plays a significant role on the mechanical strength. Larger CuO grains may act as fracture origins, which negatively affect the mechanical strength. The 20Cu/SiO2 extrudate with high Cu dispersion and high porosity is optimized for hydrogenation of DMO to EG, achieving a 98% conversion of DMO and 85% selectivity of EG under the liquid hourly space velocity (LHSV) of 1.0 h–1.
Co-reporter:Shuirong Li, Maoshuai Li, Chengxi Zhang, Shengping Wang, Xinbin Ma, Jinlong Gong
International Journal of Hydrogen Energy 2012 Volume 37(Issue 3) pp:2940-2949
Publication Date(Web):February 2012
DOI:10.1016/j.ijhydene.2011.01.009
Ni catalysts supported on ZrO2 with different crystalline phases and particle sizes were prepared to study the role of zirconia support in ethanol steam reforming for hydrogen production. Catalytic behavior of the catalysts was examined at relatively low temperature of 673 K with different contact times. The decrease in particle size of zirconia results in enhanced metal-support interaction, which accounts for the high activity of the catalyst. Regarding the impact of crystalline phase of zirconia on catalytic performance, tetragonal zirconia yields a higher activity in water gas shift reaction but a lower activity in methane steam reforming than that of monoclinic zirconia. Nevertheless, zirconia plays a secondary role in product distribution, especially at long contact times. Catalytic activity tests performed at elevated temperature demonstrated a high activity and stability of Ni/ZrO2 catalyst for hydrogen production from steam reforming of ethanol.
Co-reporter:Shengping Wang, Yun Shi, Xinbin Ma
Microporous and Mesoporous Materials 2012 Volume 156() pp:22-28
Publication Date(Web):1 July 2012
DOI:10.1016/j.micromeso.2012.02.011
A series of Ti-MCM-41 mesoporous materials with different titanium content (Si/Ti ratio varying from 100 to 5) were prepared using a microwave irradiation method. Physicochemical and structural properties of the materials were investigated using small angle X-ray powder diffraction (SAXRD), N2 adsorption–desorption, Fourier transform infrared (FT-IR) spectroscopy, transmission electron micrograph (TEM), inductively coupled plasma optical emission spectrometry (ICP-OES), diffuse reflectance UV–visible (DRUV–vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), FT-IR measure of adsorbed pyridine and ammonia temperature programmed desorption (NH3-TPD) techniques. Merging results of those characterizations mentioned above, it indicates that, with the decrease of Si/Ti ratio from 100 to 5, Ti-MCM-41 samples exhibit typical long-range order of hexagonal structure with a certain decrease of structure ordering; titanium species incorporate into the framework entirely and are mainly in tetrahedral coordination. As the titanium content increases gradually, the amount of framework Ti(IV) sites, which could result in the formation of weak Lewis acid sites on the surface, also rises correspondingly. The rich weak Lewis acid sites and mesoporous structure with large pore diameter are significant factors affecting the catalytic properties of Ti-MCM-41 materials for transesterification of dimethyl oxalate and phenol.Graphical abstractFor Ti-MCM-41, titanium species incorporate into the framework entirely and mainly exist in tetrahedral coordination. As the titanium content increases gradually, the amount of framework Ti(IV) sites, which could result in the formation of weak Lewis acid sites on the surface, are also increased correspondingly. The rich weak Lewis acid sites and mesoporous structure with large pore diameter are significant factors affecting the catalytic properties of Ti-MCM-41 materials.Highlights► A series of Ti-MCM-41 were prepared by a microwave irradiation method with different titanium content. ► Ti-MCM-41 samples exhibited typical long-range order of hexagonal structure. ► Titanium species incorporated into the framework and mainly existed in tetrahedral coordination. ► The increase of framework Ti(IV) sites resulted in the formation of more weak Lewis acid sites. ► The rich weak Lewis acid sites and mesoporous structure are favorable for the catalytic performances.
Co-reporter:Yongli Shen, Qingsen Meng, Shouying Huang, Shengping Wang, Jinlong Gong and Xinbin Ma
RSC Advances 2012 vol. 2(Issue 18) pp:7109-7119
Publication Date(Web):01 Jun 2012
DOI:10.1039/C2RA20480K
The mechanism of dimethyl carbonate (DMC) synthesis on Cu-exchanged zeolite β has been investigated employing density functional theory (DFT) calculations and a double numerical plus polarization (DNP) basis set. The adsorption energy (ΔE) and decomposition activation energy (Ea) for O2 are −1.84 and 1.72 eV, respectively, suggesting that the decomposition of O2 occurs readily under reaction conditions on the Cu site. The formed O atom further reacts with methanol to form surface-bound (CH3O)(OH)–Cu(I)/β, in which CH3O and OH were coadsorbed on the Cu+ of the catalyst; this process proceeds without an activation barrier and with an energy release of 1.23 eV. The (CH3O)(OH)–Cu(I)/β species then reacts with another methanol molecule and carbon monoxide to produce DMC through two different reaction pathways. In path I, insertion of carbon monoxide into the (CH3O)(OH)–Cu(I)/β leads to the formation of monomethyl carbonate species (CH3OCOOH), which then reacts with methanol to produce DMC and H2O. The activation energies for both steps are 0.97 and 0.65 eV, respectively. In path II, (CH3O)(OH)–Cu(I)/β reacts with methanol first to produce a dimethoxide species ((CH3O)(CH3O)–Cu(I)/β), and the formation of DMC is via the insertion of carbon monoxide into the (CH3O)(CH3O)–Cu(I)/β. The activation energies for these elementary reactions are 0.65 and 0.70 eV, respectively. The topological properties of electron density distributions for all the related stationary points involved in this reaction have also been examined using the atoms in molecule (AIM) theory for the illustration of the bond paths and weak interactions of all the stationary points in the reaction path.
Co-reporter:Yadong Ge;Yuanyuan Dong;Shengping Wang
Frontiers of Chemical Science and Engineering 2012 Volume 6( Issue 4) pp:415-422
Publication Date(Web):2012 December
DOI:10.1007/s11705-012-1214-4
The catalysts supported on LiAl5O8 (spinel) for vapor phase synthesis of dimethyl carbonate (DMC) from methyl nitrite (MN) have been studied. Their catalytic activities on supports prepared by different methods were evaluated in a continuous reactor. The samples were characterized by powder X-ray diffraction, N2 adsorption-desorption isotherms, fourier transform infrared spectroscopy and temperature-programmed reduction of H2. Li/Al molar ratio and calcination temperature greatly influence the structure of crystalline phase of Li-Al-O oxides. Desirable LiAl5O8 (spinel) was formed at 800°C, while LiAl5O8 (primitive cube) formed at 900°C is undesirable for the reaction. A high Li/Al molar ratio, which was related with LiAlO2, also slowed the reaction rate. The electron transfer ability and the interaction with active component are the important properties of the spinel-based supports. The CuCl2-PdCl2/LiAl5O8 (spinel) with better electron transfer ability and low Pd2+ reduction temperature exhibited a better catalytic ability.
Co-reporter:Shengping Wang;Xin Zhang;Yujun Zhao
Frontiers of Chemical Science and Engineering 2012 Volume 6( Issue 3) pp:259-269
Publication Date(Web):2012 September
DOI:10.1007/s11705-012-1212-6
Cordierite monoliths coated with Pd-Fe/α-Al2O3 catalysts were prepared at various calcination temperatures and characterized by thermogravimetry, temperature-programmed reduction, transmission electron microscopy, diffuse reflectance infrared Fourier transformation spectroscopy and X-ray diffraction. The performance of the catalytic monoliths for the synthesis of dimethyl oxalate (DMO) through a CO coupling reaction was evaluated. Monolithic catalysts with calcination temperatures ranging from 473 K to 673 K exhibited excellent dispersion of Pd, good CO adsorption properties, and excellent performance for the coupling reaction. The optimized monolithic catalyst exhibited a much higher Pd efficiency (denoted as DMO (g)·Pd (g)−1·h−1) (733 h−1) than that of the granular catalyst (60.2 h−1), which can be attributed to its honeycomb structure and the large pore sizes in the α-Al2O3 washcoat which was accompanied with an even distribution of the active component in the coating layer along the monoliths channels.
Co-reporter:Shuang Chen, Shengping Wang, Xinbin Ma and Jinlong Gong
Chemical Communications 2011 vol. 47(Issue 33) pp:9345-9347
Publication Date(Web):18 Jul 2011
DOI:10.1039/C1CC12391B
This communication describes the design of bifunctional VOx/TS-1 catalysts with enhanced redox and acidic character via doping SO42− and PO43− for selective oxidation of methanol to dimethoxymethane. Redox sites enable the production of formaldehyde, while acidic sites favor the condensation of formaldehyde to DMM.
Co-reporter:Shengping Wang, Yun Shi, Xinbin Ma, and Jinlong Gong
ACS Applied Materials & Interfaces 2011 Volume 3(Issue 6) pp:2154
Publication Date(Web):May 24, 2011
DOI:10.1021/am200380a
This paper describes a method to regulate porosity of Ti-containing mesoporous molecular sieves (Ti-MCM-41) by employing swelling agents that are hydrophobic in nature, such as dodecylamine, n-heptane, and sym-trimethylbenzene (TMB). Physicochemical properties of the samples were investigated using XRD, FT-IR, IR spectra of pyridine absorption, UV–vis, TEM, and N2 adsorption–desorption techniques. Addition of favorable swelling agents leads to an increase in pore size accompanied by retaining the mesostructure with a certain decrease of structure ordering. Swelling agents also have significant impact on the integration of Ti into the silica framework, which further affect the formation of Lewis acid sites. N-heptane is the most favorable agent for pore expansion of Ti-MCM-41. The material with n-heptane/CTAB ratio of 1 exhibits the largest pore size of 48.3 Ǻ, and mesopore volume of 1.266 cm3/g and narrow pore-size distribution. We also demonstrated that shape-selective transesterification catalytic activity of Ti-MCM-41 was greatly enhanced because of pore expansion.Keywords: organic carbonate; pore expansion; shape selectivity; swelling agent; Ti-MCM-41
Co-reporter:Maoshuai Li, Shuirong Li, Chengxi Zhang, Shengping Wang, Xinbin Ma, Jinlong Gong
International Journal of Hydrogen Energy 2011 Volume 36(Issue 1) pp:326-332
Publication Date(Web):January 2011
DOI:10.1016/j.ijhydene.2010.09.084
This paper describes a study regarding the effect of Ni addition to NixMg1−xO solid solutions on the catalytic performances of ethanol steam reforming for hydrogen production. Nickel nanoparticles supported on NixMg1−xO demonstrated higher conversion of ethanol and yields of hydrogen than the bare support. We correlated the improved performances of Ni-based catalysts with the reducibility of nickel species. The addition of Ni to the solid solution support produced more easily reducible surface nickel species. Higher content of bulk nickel species in the support could inhibit the surface nickel species from diffusing into the bulk, leading to more surface nickel species that is easily reducible to its active form.
Co-reporter:Xiaodong Wang, Maoshuai Li, Shuirong Li, Hao Wang, Shengping Wang, Xinbin Ma
Fuel Processing Technology 2010 Volume 91(Issue 12) pp:1812-1818
Publication Date(Web):December 2010
DOI:10.1016/j.fuproc.2010.08.003
Thermodynamic analysis and experimental tests of glycerol steam reforming with/without calcium oxide (CaO) as a carbon dioxide (CO2) sorbent have been performed and compared in this work. Methanol, ethanol, acetaldehyde, acetone and ethylene do not exist in equilibrium conditions according to the equilibrium calculations. Without CaO present, thermodynamic predictions show that a maximum hydrogen concentration of 67% can be obtained at 925 K, with a water to glycerol ratio (WGR) of 9. In the experiments, the Ni/ZrO2 catalyst fails to catalyze the reactions to thermodynamic equilibrium under the selected conditions as the highest hydrogen concentration obtained is 64%. With the presence of CaO, thermodynamic analysis implies hydrogen purity exceeding 95% can be achieved below 925 K at WGRs of 6 and 9. However, CaCO3 does not exist at temperatures greater than 1025 K. In the experiments, a hydrogen purity of 95% with only 5% CH4 as impurity can be reached at 850 K with a WGR of 9. The Ni/ZrO2 catalyst is not active enough to convert excess CH4 to hydrogen in glycerol steam reforming as CH4 concentrations are usually higher than the equilibrium values. The addition of CaO to this system greatly enhances the hydrogen production while reducing the CO concentration.
Co-reporter:Maoshuai Li, Xiaodong Wang, Shuirong Li, Shengping Wang, Xinbin Ma
International Journal of Hydrogen Energy 2010 Volume 35(Issue 13) pp:6699-6708
Publication Date(Web):July 2010
DOI:10.1016/j.ijhydene.2010.04.105
Nickel based catalysts derived from thermal decomposition of Ni/Mg/Al hydrotalcite-like precursors have been studied in ethanol steam reforming (ESR) for hydrogen production. X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature-programmed reduction (TPR) and thermogravimetric analysis (TGA) were used to investigate the physic-chemical properties of the catalysts prepared. The catalysts being mainly composed of Ni–Mg–O solid solution phase exhibited high activity and stability for ethanol steam reforming. Ethanol could be completely converted even at 673 K, and hydrogen concentration tended to increase with increasing reaction temperature, gas hourly space velocity (GHSV) and Ni/Mg ratio. XRD and TEM investigations demonstrate that low Ni/Mg ratio led to insufficient Ni0 phase available, which may result in decreasing activity and stability due to coke formation observed on the NiMg10 (Ni/Mg = 1/10) catalyst. High reduction pretreatment temperature (>973 K) could promote the reduction of Ni0 metal, and effectively improve the catalytic activity and stability. The optimum reduction temperature might be 1073 K, at which proper amount of Ni0 species and good resistance to coke formation could be obtained.
Co-reporter:Xiaodong Wang, Na Wang, Maoshuai Li, Shuirong Li, Shengping Wang, Xinbin Ma
International Journal of Hydrogen Energy 2010 Volume 35(Issue 19) pp:10252-10256
Publication Date(Web):October 2010
DOI:10.1016/j.ijhydene.2010.07.140
Thermodynamic features of hydrogen production by glycerol steam reforming with in situ hydrogen extraction have been studied with the method of Gibbs free energy minimization. The effects of pressure (1–5 atm), temperature (600–1000 K), water to glycerol ratio (WGR, 3–12) and fraction of H2 removal (f, 0–1) on the reforming reactions and carbon formation were investigated. The results suggest separation of hydrogen in situ can substantially enhance hydrogen production from glycerol steam reforming, as 7 mol (stoichiometric value) of hydrogen can be obtained even at 600 K due to the hydrogen extraction. It is demonstrated that atmospheric pressure and a WGR of 9 are suitable for hydrogen production and the optimum temperature for glycerol steam reforming with in situ hydrogen removal is between 825 and 875 K, 100 K lower than that achieved typically without hydrogen separation. Furthermore, the detrimental influence of increasing pressure in terms of hydrogen production becomes marginal above 800 K with a high fraction of H2 removal (i.e., f = 0.99). High temperature and WGR are favorable to inhibit carbon production.
Co-reporter:Hao Wang, Xiaodong Wang, Maoshuai Li, Shuirong Li, Shengping Wang, Xinbin Ma
International Journal of Hydrogen Energy 2009 Volume 34(Issue 14) pp:5683-5690
Publication Date(Web):July 2009
DOI:10.1016/j.ijhydene.2009.05.118
In this work, thermodynamics was applied to investigate the glycerol autothermal reforming to generate hydrogen for fuel cell application. Equilibrium calculations employing the Gibbs free energy minimization were performed in a wide range of temperature (700–1000 K), steam to glycerol ratio (1–12) and oxygen to glycerol ratio (0.0–3.0). Results show that the most favorable conditions for hydrogen production are achieved with the temperatures, steam to glycerol ratios and oxygen to glycerol ratios of 900–1000 K, 9–12 and 0.0–0.4, respectively. Further, it is demonstrated that thermoneutral conditions (steam to glycerol ratio 9–12) can be obtained at oxygen to glycerol ratios of around 0.36 (at 900 K) and 0.38–0.39 (at 1000 K). Under these thermoneutral conditions, the maximum number of moles of hydrogen produced are 5.62 (900 K) and 5.43 (1000 K) with a steam to glycerol ratio of 12. Also, it should be noted that methane and carbon formation can be effectively eliminated.
Co-reporter:Xiaodong Wang, Shuirong Li, Hao Wang, Bo Liu and Xinbin Ma
Energy & Fuels 2008 Volume 22(Issue 6) pp:4285-4291
Publication Date(Web):October 24, 2008
DOI:10.1021/ef800487r
Thermodynamic properties of glycerin steam reforming have been studied with the method of Gibbs free energy minimization for hydrogen and/or synthesis gas production. Equilibrium compositions including the coke-formed and coke-free regions were determined as a function of water/glycerin molar ratios (1:1−12:1) and reforming temperatures (550−1200 K) at different pressures (1−50 atm). Optimum conditions for hydrogen production are temperatures between 925 and 975 K and water/glycerin ratios of 9−12 at atmospheric pressure, whereas temperatures above 1035 K and water/glycerin ratios between 2 and 3 at 20−50 atm are suitable for the production of synthesis gas that favors both methanol synthesis and low-temperature Fischer−Tropsch synthesis. However, synthesis gas obtained from glycerin steam reforming is not feasible for direct use in high-temperature Fischer−Tropsch synthesis. Under these optimum conditions, carbon formation can be thermodynamically inhibited.
Co-reporter:Xinbin Ma, Jinlong Gong, Shengping Wang, Fei He, Hongli Guo, Xia Yang, Genhui Xu
Journal of Molecular Catalysis A: Chemical 2005 Volume 237(1–2) pp:1-8
Publication Date(Web):2 August 2005
DOI:10.1016/j.molcata.2005.04.052
The transesterification of dimethyl oxalate (DMO) with phenol over stannum modified TS-1 was conducted to prepare methyl phenyl oxalate (MPO) and diphenyl oxalate (DPO), which could be used to produce diphenyl carbonate (DPC). The component, structure and phase of TS-1 catalysts with various Sn loadings were investigated. The relationship between the catalytic properties and the Sn loadings was discussed. The results indicated that, although the Sn-modified TS-1 catalysts had fewer Lewis acid sites than the unmodified TS-1, its catalytic activity was increased greatly by the interaction of Sn with Ti–O–SiO3 weak Lewis acid centers. The catalyst of TS-1 with 2 wt% Sn loadings performed best, giving 50.3% conversion of dimethyl oxalate and 99.2% selectivity to the target products. By means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX), the relationship between the catalytic properties and the structure of Sn dispersed on the surface of TS-1 was studied in detail. At Sn loadings below 2 wt%, Sn was highly dispersed, but at higher loadings it was crystallized into bulk tin dioxide, where the interaction between Ti and Sn was not evidently observed, leading to decreased catalytic activity. XPS results showed that Ti could not be detected even at 1 wt% Sn loadings. EDX results indicated that the content of Ti on the surface decreased with increasing Sn loadings, but the decrease in Ti content was much less than the increase in Sn content. Moreover, NH3-TPD and FTIR analyses of adsorbed pyridine showed that there were only weak Lewis acid centers on all catalysts and the Sn loadings hardly affected the acid strength of the catalysts.Stannum modified titanium silicalite TS-1 has proved to be an effective catalyst for the transesterification of dimethyl oxalate with phenol to produce methyl phenyl oxalate (MPO) and diphenyl oxalate (DPO), the important intermediates for diphenyl carbonate (DPC) synthesis.
Co-reporter:Xinbin Ma, Hongli Guo, Shengping Wang, Yongli Sun
Fuel Processing Technology 2003 Volume 83(1–3) pp:275-286
Publication Date(Web):15 September 2003
DOI:10.1016/S0378-3820(03)00075-4
The transesterification of dimethyl oxalate with phenol to produce methyphenyl oxalate and diphenyl oxalate was carried out in liquid phase using a heterogeneous catalyst. The evaluation results showed that TS-1 had better activity and excellent selectivity to target products compared with many conventional ester exchange catalysts tested. Two hours as the duration of the reaction was appropriate. Under the catalytic reaction conditions, framework IR and the reaction results jointly proved that the best calcination temperature was 823 K at which the amount of acid sites measured by IR of adsorbed pyridine reached a maximum. X-ray diffraction of TS-1 did not show much variation with changing calcination temperatures from 723 to 923 K. The characterization of the catalyst, by means of IR of adsorbed pyridine and NH3-TPD indicated that the desired catalytic activity of TS-1 could be ascribed to its weak Lewis acidity. Tin modified TS-1 showed a better performance in activity and selectivity. The conversion of dimethyl oxalate was improved up to 50.3% when Sn loading was 2, while the selectivity was above 99% over all Tin modified TS-1 molecular sieves.
Co-reporter:Zhenhua Li, Ye Tian, Jia He, Baowei Wang, Xinbin Ma
Journal of Energy Chemistry (September 2014) Volume 23(Issue 5) pp:625-632
Publication Date(Web):1 September 2014
DOI:10.1016/S2095-4956(14)60193-5
In this study, different methods were used to prepare MoO3/ZrO2 catalysts for sulfur resistant methanation reaction. It was found that MoO3/ZrO2 catalyst prepared by one-step co-precipitation method achieved high methanation performance. CO conversion could reach up to 90% on 25 wt% MoO3/ZrO2 catalyst, much higher than that on the conventional 25 wt% MoO3/Al2O3 catalyst. The Mo-based catalysts were characterized by XRF, XRD, Raman, BET, TEM and H2-TPR etc. It was found that MoO3 particles were highly dispersed on ZrO2 support for 25 wt% MoO3/ZrO2 catalyst prepared at 65–85 °C because of its relatively larger pore size, which contributed to a high CO conversion. Meanwhile, when MoO3 loading exceeded the monolayer coverage, the formed crystalline MoO3 and ZrMo2O8 might block the micropores of the catalyst and make the methanation activity declined. These results are useful for preparing highly efficient catalyst for CO methanation process.MoO3/ZrO2 catalysts for CO methanation, prepared by one-step co-precipitation method, achieved higher methanation performance than the conventional MoO3/Al2O3 catalyst. This attributes to that MoO3 particles were small and highly dispersed on ZrO2 support.Download full-size image
Co-reporter:Shuo Zhao, Hairong Yue, Yujun Zhao, Bo Wang, Yaochen Geng, Jing Lv, Shengping Wang, Jinlong Gong, Xinbin Ma
Journal of Catalysis (January 2013) Volume 297() pp:142-150
Publication Date(Web):1 January 2013
DOI:10.1016/j.jcat.2012.10.004
The long-term stability and activity of catalysts are vital for vapor-phase selective hydrogenation of dimethyl oxalate to synthesize ethanol. Boron has been widely employed as a modifier for transition-metal catalysts mainly to, improve selectivity and stability. We introduced boron species by impregnation into silica-supported copper catalysts prepared by an ammonia evaporation hydrothermal method and investigated their catalytic activity and thermal stability for hydrogenation of dimethyl oxalate. The effect on activity mainly depends on the amount of boron and an optimal Cu/B molar ratio of 3 was obtained. The characterization of the catalysts shows that boron-modified Cu/SiO2 facilitates the dispersion of copper species, enhances the metal–support interaction, and suppresses the growth of copper particles during dimethyl oxalate hydrogenation.Graphical abstractThis paper describes the origin of the reactivity and stability of boron-modified copper-based catalysts with prolonged lifespan for the vapor-phase selective hydrogenation of dimethyl oxalate to ethanol.Download high-res image (118KB)Download full-size imageHighlights► A low-cost copper-based catalyst for synthesis of ethanol with high efficiency. ► Boron modification is a readily available approach for improving the stability. ► Boron could improve the copper dispersion and suppress the growth of Cu particles. ► Boron affects the acidic/basic sites and enhances the metal–support interaction.
Co-reporter:Bao-wei WANG, Da-jun MENG, Wei-han WANG, Zhen-hua LI, Xin-bin MA
Journal of Fuel Chemistry and Technology (December 2016) Volume 44(Issue 12) pp:1479-1484
Publication Date(Web):1 December 2016
DOI:10.1016/S1872-5813(17)30003-8
Citric acid hold great promise to improve the Mo-based catalyst performance for hydrogenation reaction applications. MoO3/CeO2-Al2O3 catalysts were prepared by impregnation method with adding citric acid into CeO2-Al2O3 composite supports and tested for sulfur resistant methanation. The syngas methanation activity increased with the increase of citric acid additive amount, and CO conversion could reach up 60% when the molar ratio of citric acid to Ce was 3. The prepared catalysts were characterized by BET, H2-TPR, XRD and XPS. The increased catalytic performance was mainly attributed to the increased amount of Ce species on the surface of catalysts which could decreased the interaction force between MoO3 and CeO2-Al2O3 supports. Additionally, the increased specific surface of CeO2-Al2O3 composite support was also in favor of catalytic performance.
Co-reporter:Yue Liu, Xinbin Ma, Shengping Wang, Jinlong Gong
Applied Catalysis B: Environmental (30 November 2007) Volume 77(Issues 1–2) pp:125-134
Publication Date(Web):30 November 2007
DOI:10.1016/j.apcatb.2007.07.011
Co-reporter:Jinlong Gong, Xinbin Ma, Shengping Wang
Applied Catalysis A: General (2 January 2007) Volume 316(Issue 1) pp:1-21
Publication Date(Web):2 January 2007
DOI:10.1016/j.apcata.2006.09.006
Co-reporter:Shuang Chen, Shengping Wang, Xinbin Ma and Jinlong Gong
Chemical Communications 2011 - vol. 47(Issue 33) pp:NaN9347-9347
Publication Date(Web):2011/07/18
DOI:10.1039/C1CC12391B
This communication describes the design of bifunctional VOx/TS-1 catalysts with enhanced redox and acidic character via doping SO42− and PO43− for selective oxidation of methanol to dimethoxymethane. Redox sites enable the production of formaldehyde, while acidic sites favor the condensation of formaldehyde to DMM.
Co-reporter:Jinlong Gong, Zhihong Nie and Xinbin Ma
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 29) pp:NaN11987-11987
Publication Date(Web):2013/06/27
DOI:10.1039/C3CP90089D
A graphical abstract is available for this content
Co-reporter:Huimin Zhan, Shouying Huang, Ying Li, Jing Lv, Shengping Wang and Xinbin Ma
Catalysis Science & Technology (2011-Present) 2015 - vol. 5(Issue 9) pp:NaN4389-4389
Publication Date(Web):2015/05/06
DOI:10.1039/C5CY00460H
To investigate the role of Cu species in dimethyl ether (DME) carbonylation over Cu/H-MOR catalysts, ion-exchange with copper ammonia solution (Cu/H-M(x)) and solid state ion-exchange with CuCl (SSIE Cu/H-M(x)) methods were applied to prepare a series of samples with different Cu loadings. Compared to H-MOR, the reduced Cu/H-M(x) samples dramatically facilitated the conversion of DME, in which Cu+ and Cu0 species as well as Brønsted acid sites coexisted. Physical adsorption, powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) were carried out to prove the negligible influence of the preparation processes on the textural and morphological properties of MOR. Fourier transform infrared (FTIR) spectroscopy, adsorption of pyridine, CO temperature programmed desorption (CO-TPD), and X-ray photoelectron spectroscopy (XPS) were employed to qualitatively and quantitatively explore the variation of both Brønsted acid sites and Cu species in 8-membered ring (8-MR) and 12-membered ring (12-MR) channels. With an increase of the Cu dopant, the amount of Cu0 increased gradually while Cu+ had no obvious regularity. The relationship between Cu0 and catalyst activity was established for Cu/H-M(x) catalysts. In addition, the formation of methyl acetate (MA) over SSIE Cu/H-M(x) catalysts decreased sharply with increasing Cu+ loading, which further excluded the promoting effect of Cu+ species present in MOR.
Co-reporter:Yongli Shen, Qingsen Meng, Shouying Huang, Jinlong Gong and Xinbin Ma
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 31) pp:NaN13127-13127
Publication Date(Web):2013/05/30
DOI:10.1039/C3CP51092A
Density functional theory (DFT) calculations have been used to investigate the oxidative carbonylation of methanol on Pd(II)/β zeolite. Activation energies for all the elementary steps involved in the commonly accepted mechanism, including the formation of dimethyl carbonate, methyl formate and dimethoxymethane, are presented. Upon conducting the calculations, we identify that the Pd2+ cation bonded with four O atoms of the zeolite framework acts as the active site of the catalyst. Molecularly adsorbed methanol starts to react with oxygen molecules to produce a methanediol intermediate (CH2(OH)2) and O atom. Then, another methanol can react with the O atom to produce the (CH3O)(OH)–Pd(II)/β zeolite species. (CH3O)(OH)–Pd(II)/β zeolite can further react with carbon monoxide or methanol to give monomethyl carbonate or di-methoxide species ((CH3O)2–Pd(II)/β zeolite). Dimethyl carbonate can form via two distinct reaction pathways: (I) methanol reacts with monomethyl carbonate or (II) carbon monoxide inserts into di-methoxide. Our calculation results show the activation energy of reaction (I) is too high to be achieved. The methanediol intermediate is unstable and can decompose to formaldehyde and H2O immediately. Formaldehyde can either react with an O atom or methanol to form formic acid or a CH3OCH2OH intermediate. Both of them can react with methanol to form the secondary products (methyl formate or dimethoxymethane). Upon conducting calculations, we confirmed that the activation energies for the formation of methyl formate and dimethoxymethane are higher than that of dimethyl carbonate. All these conformations were characterized at the same calculation level.
Co-reporter:Shouying Huang, Bing Yan, Shengping Wang and Xinbin Ma
Chemical Society Reviews 2015 - vol. 44(Issue 10) pp:NaN3116-3116
Publication Date(Web):2015/03/20
DOI:10.1039/C4CS00374H
Dialkyl carbonates are important organic compounds and chemical intermediates with the label of “green chemicals” due to their moderate toxicity, biodegradability for human health and environment. Indeed, owing to their unique physicochemical properties and versatility as reagents, a variety of phosgene-free processes derived from CO or CO2 have been explored for the synthesis of dialkyl carbonates. In this critical review, we highlight the recent achievements (since 1997) in the synthesis of dialkyl carbonates based on CO and CO2 utilization, particularly focusing on the catalyst design and fabrication, structure–function relationship, catalytic mechanisms and process intensification. We also provide an overview regarding the applications of dialkyl carbonates as fuel additives, solvents and reaction intermediates (i.e. alkylating and carbonylating agents). Additionally, this review puts forward the substantial challenges and opportunities for future research associated with dialkyl carbonates.
