Mesoporous WO3–TiO2 support was synthesized by hydrothermal method, mesoporous V2O5/WO3–TiO2 catalyst was synthesized by impregnation method and used for selective catalytic reduction (SCR) of NOx with a excellent NOx conversion at a wider operating temperature ranging from 200 to 460 °C. In the range of 260–440 °C, NOx conversion reached to 98.6%, and nearly a complete conversion. Even with the existence of 300 ppm SO2, NOx conversion was only a little decline. The catalyst was characterized by a series of techniques, such as XRD, BET, XPS, TEM, Raman and H2-TPR. It was concluded that V2O5/WO3–TiO2 catalyst was ascribe to antase TiO2, and also the high crystallinity of anatase TiO2 could improve the SCR performance. More interested, V2O5/WO3–TiO2 catalyst exhibited the typical mesoporous structure according to the BET results. In addition, the TEM results indicated that the active components of V and W were well-dispersed on the surface of TiO2, while the enhancement of dispersion could improve the activity of catalysts. More importantly, the concentration ratio of V4+/(V5+ + V4+ + V3+) performed the key role in improving the activity of V2O5/WO3–TiO2 catalyst.

•The surface oxygen concentration and defects was a key for CO oxidation.•The oxygen functional group and defect increased oxygen content and vacancies.•Certain moisture was conducive to oxidize of CO.•CO oxidation reaction pathway under dry and moisture condition was various.The oxygen functional groups and defects of carbon material played an important role in dispersion of active components and additives, reduction of Ce4+, etc. The reduction of Ce4+ and structure defects would increase surface oxygen concentration and oxygen vacancies. The dispersion of active components and additives, surface oxygen concentration and structure defects were key factor on CO oxidation. The oxygen functional groups and structure defects of porous carbon spheres (PCSs) increased by O3 treatment method. The effects of O3 treatment concentration on structures, properties of PCSs support and Pd-Ce/PCSs were investigated in detail. The particle size of PCSs had not been changed basically after O3 treatment. However, the outer of PCSs became uneven, which was main reason of the external surface area increase. The content of surface Pd4+, surface adsorption oxygen concentration, oxygen vacancies, defects, increased with increasing O3 treatment concentration. Relationship between the functional groups, defects of porous carbon spheres and their catalytic performance was investigated in detail. CO oxidation test showed that the Pd-Ce based catalysts supported by the PCSs after O3 treatment concentration for 45 mgL−1 had the best activity. The effect of moisture on CO conversion was explored, and the catalysts showed excellent stability under moisture condition.In this paper, the surface oxygen concentration and defects of porous carbon spheres were adjusted by altering O3 treatment concentration. The catalysts activity increased with increasing O3 concentration. The optimization catalyst emerged superior catalytic activity and water resistance.Download high-res image (294KB)Download full-size image

•Ordered mesoporous Al2O3 were synthesized by EISA method.•CuMn-Al2O3 catalysts were synthesized by co-impregnation method.•The Oads, Cu+ species were main activity species of CuMn-Al2O3 catalysts.•The CuMn-400 showed the highest catalytic activity.In this paper, by controlling the calcination temperature, ordered mesoporous Al2O3 with controllable pore diameters were rationally designed and synthesized by evaporation-induced self-assembly method. The CuMn-Al2O3 catalysts with different pores were synthesized by a co-impregnation method with ordered mesoporous Al2O3 as template. These catalysts expressed ordered mesoporous structure, possessed higher specific surface area and large pore volume, and owned more surface active sites, which were helpful for CO oxidation. When the calcination temperature of Al2O3 was 400 °C, this catalyst showed the highest catalytic activity. The reason was due to its relatively stronger redox ability and surface activity species. More Cu+ and chemisorbed oxygen concentration was very useful in achieving the highest catalytic performance.In this paper, by controlling the calcination temperature, ordered mesoporous Al2O3 with different pores were synthesized by EISA method. The CuMn-Al2O3 catalysts were synthesized by co-impregnation method with ordered mesoporous Al2O3 as template. The CuMn-400 showed the highest catalytic activity. Schematic diagram illustrating the preparation of ordered mesoporous CuMn-Al2O3 catalysts.Download high-res image (307KB)Download full-size image

In this paper, a Pd/reduced graphene oxide (Pd/RGO) catalyst was successfully synthesized by a chemical reduction method with hydrazine hydrate as a reducing agent. By controlling the amount of reducing agent, the Pd/RGO catalyst showed different surface Pd loadings and graphene interlayer spacings. The Pd/Fe@RGO catalyst was prepared by Pd supported on the Fe@RGO composite which was synthesized by a hydrothermal method. In the Pd/Fe@RGO catalyst, Pd0 species and Fe3+ species were the main active components. The addition of Fe species increased the interlayer spacing of graphene, the surface loading of Pd and the content of surface active oxygen. Thus, the Pd/Fe@RGO catalyst showed the highest catalytic activity for CO oxidation, and the T100 value was 90 °C and the apparent activation energy was 86.37 kJ mol−1. The superior catalyst at 50% conversion was stable for 510 min, and under moisture the catalyst was stable for only 300 min.

The design and development of heterogeneous catalysts is very critical for the synthesis of various chemicals and fuels derived from superfluous biomass. The synthesis of biofuel 2-methylfuran typically derives from the conversion of the formyl group of biomass-derived furfural, because this process is very valuable in terms of the amelioration and remission of the environment and energy crisis. Herein, we designed a series of bifunctional catalysts formed in line with the spatial restriction strategy by anchoring copper nanoparticles (Cu NPs) on phyllosilicate-like structures to enhance copper dispersion and provide properly assembled Lewis acid sites to promote the hydrogenation and hydrogenolysis of the formyl group in furfural, and first applied them to the conversion of the formyl group with high efficiency. However, the modulation of the Cu–Si molar ratio is extremely critical to the possible reduction of metal consumption, full exploitation of the prerequisite metal sites and great improvement of activity. In this work, the catalyst with a Cu–Si molar ratio (actual value = 0.33) lower than that of the industrial catalyst (theoretical value = 1.0) exhibited higher yields of the intermediate furfuryl alcohol (yield = 83.4%) and the desired product 2-methylfuran (yield = 95.5%). More importantly, with the continuous increase of the Cu–Si molar ratio, it is discovered that Cu dispersion regularly decreased and the size of the Cu NPs sequentially increased, and the change of assembled Lewis acid sites surprisingly kept pace with the integrity of the layered structure, as revealed by a series of detailed characterization studies.

•A bifunctional Co/GO catalyst was obtained by a typical hydrothermal method.•The Co/GO catalyst exhibits an unexpected, surprisingly high CO activity.•The bifunctional Co/GO–300 °C catalyst can convert completely CO into CO2 at 51 °C.•The synergistic effect between the oxygen-containing groups and Co3+ species.Despite tremendous efforts, developing a series of heterogeneous catalysts for CO oxidation elimination with high activity at low cost remains a great challenge. Here, we report a bifunctional Co-based nanocrystals anchoring in the graphene oxide layer as a high-performance catalyst for CO oxidation. Although a single cobalt or graphene oxide catalysts alone have the lower catalytic activity, their combination exhibits an unexpected, surprisingly high CO activity that is further enhanced by a series of oxygen-containing functional groups on the surface of graphene oxide sheets. The Co/graphene oxide calcined at 300 °C (Co/GO–300 °C) exhibits the outstanding catalytic activity with T100 = 51 °C but superior stability, producing a high-performance non-precious metal-based catalyst for CO oxidation elimination. Under a series of critical characterizations, the unusual catalytic activity of Co/GO–300 °C sample is attributed to the synergistic effect between the oxygen-containing functional groups of graphene oxide sheets and Co species. Especially, the existence of Co3+ species could promote the adsorption and activation of CO molecules.Download full-size image

•A novel catalyst composed of Cu–Mn and CaO–ZrO2 was used to synthesize MF from syngas.•Cu1.5Mn1.5O4 and the reducibility of Cu–Mn catalyst play a significant role in MF synthesis.•Nucleophilic addition–elimination reaction mechanism was prpposed for the MF synthesis from syngas.Cu–Mn mixed oxides with different calcination temperatures were prepared using ammonia complexing method and evaluated for methyl formate (MF) synthesis from syngas with CaO–ZrO2 as co-catalyst. The influence of calcination temperature on the structure and properties of Cu–Mn mixed oxides was investigated by appropriate characterizations. Cu1.5Mn1.5O4 formed during the calcination of Cu–Mn catalyst at 450 °C and played a significant role in the MF synthesis. However, it partially decomposed into CuO and MnO2 when the calcination temperature exceeded 550 °C. Results showed that the optimum MF selectivity was obtained on Cu–Mn catalyst calcined at 450 °C, and the highest CO conversion was obtained on the Cu–Mn sample with calcination temperature of 550 °C. The reaction mechanism of MF synthesis from syngas over Cu–Mn mixed oxides and CaO–ZrO2 co-catalyst was thoroughly studied via typical model reactions, and the nucleophilic addition–elimination reaction mechanism was proposed.Download high-res image (115KB)Download full-size image

Mesoporous ceria–titanium catalysts were synthesized by one pot hydrothermal method and used for selective catalytic reduction (SCR) of NO with nearly complete NO conversion over a wide operating temperature range. The outstanding activity of the ceria–titanium catalyst was attributed to the tunable particle size and the efficient control of surface areas and pore volume in the range of 260–400 °C by the modulation of the soft template content. Especially, ceria oxide (CeO2) active centers being highly dispersed and titanium oxide (TiO2) with sufficient surface areas and uniform pore canals are the main reasons for the excellent SCR performance. For a series of catalysts, H-Ce0.2TiOx-2 exhibited nearly complete NO conversion (99%) in the range of 260 °C to 400 °C, with excellent stability and desired resistance to H2O. In addition, we discussed the reaction and deactivation mechanisms of ceria–titanium catalysts for the SCR, resulting from better redox ability and abundant acid sites. In view of the simple process and outstanding stability of mesoporous ceria–titanium catalysts, this could be treated as an ideal candidate for real applications.

In this paper, three-dimensional (3D) Cu–Ce-Ox catalysts with controllable pore diameters were rationally designed and synthesized by a facile hard-template method. By controlling the calcination temperature, the 3D Cu–Ce-Ox catalysts with different pores were synthesized by nano-replication technology with KIT-6 as hard template. These catalysts expressed 3D pore structure, possessed higher pore volume and large pores, and owned more surface active sites, which were helpful for CO oxidation. When the calcination temperature of Cu–Ce-Ox was 600 °C, this catalyst showed the highest catalytic activity. The reason was due to its relatively stronger redox ability and surface activity species. More Ce3+, Cu+ and chemisorbed oxygen concentration was very useful in achieving the highest catalytic performance.

•3D Cu-Ce-Ox catalysts were synthesized by a facile hard-template method.•KIT-6 with different pores was prepared by changing the hydrothermal time.•The Ce3+, Cu+ species were main activity site of Cu-Ce-Ox.•The highest catalytic activity when the hydrothermal time is 24 h.In this paper, 3D Cu-Ce-Ox catalysts with controllable pore diameters were rationally designed and synthesized by a facile hard-template method. By controlling the hydrothermal synthesis time, mesoporous silica KIT-6 with different pores were prepared. Then, the 3D Cu-Ce-Ox catalysts were synthesized by nano-replication technology with KIT-6 as hard template. These catalysts expressed 3D pore structure, possessed higher pore volume and large pores, and owned more surface active sites, which were helpful for CO oxidation. When the synthesis time of KIT-6 was 24 h, this catalyst showed the highest catalytic activity. The reason was due to its relatively stronger redox ability and surface activity species. More Ce3+, Cu+ and chemical adsorbed oxygen concentration was very useful in achieving the highest catalytic performance.In this paper, 3D Cu-Ce-Ox catalysts with controllable pore diameters were synthesized by a hard-template method. By controlling the hydrothermal synthesis time, mesoporous silica KIT-6 with different pores were prepared. The CeCu20-KIT-6-24 showed the highest catalytic activity, where CO can be fully oxidized at 65 °C and expressed excellent stability.

Nanosized dispersive flake-like magnesium hydroxide (Mg(OH)2) had been prepared by a hydrothermal method. In the process, when the surfactant polyvinyl pyrrolidone was added, high dispersion, small particle size and large specific surface area of hexagonal crystal magnesium hydroxide was obtained by ultrasonic dispersion and temperature program. The flame retardant of Mg(OH)2 was systematically explored by scanning electron microscope (SEM), transmission electron microscopy, X-ray diffraction, BET analysis and thermo-gravimetric analysis tests. SEM showed the formation of uniform and small size magnesium hydroxide particle with hexagonal nanoscale. Under the optimized conditions, high nano-sized hexagonal Mg(OH)2 was acquired with a mean particle size of 134 nm and a specific surface area of 26.66 m2/g. According to TGA results, the sample’s decomposition temperature was 626.9 K, which was consistent with the reported literature. It is vitally prospected that the prepared hexagonal Mg(OH)2 is to be applied to the industry as a flame retardant.

•Monolith catalyst was prepared by impregnated collosol with strong adhesion force.•Monolith catalyst possesses strong adhesion force and homogeneous distribution.•Conversion ratio was more than 90% under GHSV of 5000 h−1.•An appropriate thickness of coating layer has advantageous effect for reaction.A series of monolithic V2O5–WO3/TiO2 catalysts with different vanadium and tungsten supported amounts were synthesized via coated mixed colloid, which contained certain amount of activity component. The layer coated on the ceramic substrate obtained a homogeneous distribution with strong adhere force and deep penetration with the collosol dipping into honeycomb ceramic according to the result of ultrasonic measurement and scanning electron microscopy (SEM). The new coating procedure was benefit to form highly dispersed species and generated more active site based on the result of XRD and Raman. In contrast with blank ceramic, monolithic catalyst possessed larger specific surface area and appropriate ratio of macrospore and microspores. X-ray photoelectron spectroscopy (XPS) confirmed the co-existence of pentavalent vanadium and tetravalent vanadium in the catalyst, which was favorable for NH3-SCR reaction. The monolithic catalyst exhibited desirable activity with the NOx conversion ratio beyond 90% at 440 °C and a remarkable resistance to poisoning in SO2 and H2O in the NH3-SCR reaction.In this paper, monolithic V2O5-WO3/TiO2 catalyst was prepared by investigating the coating technology in detailed. The monolithic catalyst exhibited desirable activity and a remarkable resistance to poisoning in SO2 and H2O in the NH3-SCR reaction. At the same time, the monolithic V2O5-WO3/TiO2 catalyst expressed the superior mechanical strength.

Zinc-containing MFI-type ZSM-5 zeolites were synthesized with ammonia coordinated zinc solution as zinc source, n-butyl amine as template and ZSM-5 as seeds by a facile one-step hydrothermal method, which exhibited outstanding performance for selective catalytic reduction NO with NH3 over a wide temperature range. The powder X-ray diffraction detected results showed that there was no other crystalline phase except for ZSM-5 phase and IR analysis suggested that the zinc had successfully incorporated into the zeolite framework was the vibration absorption peak at 1080 and 1230 cm−1 were broadened, which were assigned to asymmetric stretching of Si–O–Si. With the amount of zinc increases, big changes of morphologies, specific area and pore volume occurred which were collected by scanning electron microscope and Brunauer Emmett Teller Method. And the content of zinc species in the synthesized system was able to coordinate the growth size of the crystal. Furthermore, the addition of seeds would basically effectively prohibit the twin growth among these Zn-containing ZSM-5 crystals was firstly brought forward.

In this paper, mesoporous carbon (meso-C) with three-dimensional mesoporous channels was synthesized through a nanocasting route using three-dimensional mesoporous silica KIT-6 as the template. Mesoporous carbon wrapped Pd–Fe nanocomposite catalysts were synthesized by the co-precipitation method. The effects of the experimental conditions, such as pH value, Fe loading content and calcination temperature, on CO oxidation were studied in detail. The prepared Pd–Fe/meso-C catalysts showed excellent catalytic activity after optimizing the experimental conditions. The surface tetravalent Pd content, existing forms of Fe species, surface chemical adsorbed oxygen concentration, and pore channels of mesoporous carbon played vital roles in achieving the highest performance for the Pd–Fe/meso-C catalyst. The reaction pathway was conjectured according to the XPS analysis of the Pd–Fe/meso-C catalysts for CO oxidation, which maybe adhered to the Langmuir–Hinshelwood + redox mechanism. The effect of moisture on CO conversion was investigated, and the superior Pd–Fe/meso-C catalyst could maintain its activity beyond 12 h. This catalyst also showed excellent activity compared to the reported values in the existing literature.

In this paper, three kinds of carbon materials, i.e., carbon spheres (non-C), microporous carbon (micro-C) and mesoporous carbon (meso-C) were synthesized. Micro-C and meso-C were prepared by adopting the microporous low silica ZSM-5 and mesoporous silica KIT-6 as templates, respectively and non-C was prepared by a hydrothermal route. The palladium loaded non-C, micro-C and meso-C supports were prepared by an impregnation method, and the catalysts were applied for CO oxidation. The Pd/meso-C exhibited the highest catalytic activity because the meso-C support had a well-ordered mesoporous structure, large BET surface area, porous channels and higher dispersion of Pd nanoparticles. By adjusting the promoter type and content, calcined temperature, the optimal prepared conditions of the catalyst were achieved: Ce loading content = 10 wt%, calcined temperature = 200 °C. Comparing the result of the characterization and activity, it was discovered that the Pd–Ce/meso-C-200 catalyst had a large number of active surface oxygen species, Ce3+ cationic species and Pd4+ cationic species. All of these were relatively conducive to the catalytic oxidation of CO.

By using mesoporous silica KIT-6 with different hydrothermal temperature as a template, Cu-doped CeO2 catalysts with different pore diameters were successfully prepared. When KIT-6-50 (hydrothermal synthesis of mesoporous silica KIT-6 temperature was 50 °C) and KIT-6-100 (hydrothermal synthesis of mesoporous silica KIT-6 temperature was 100 °C) were employed as the hard template, the uncoupled sub-framework Cu-doped CeO2 catalyst formed. When KIT-6-130 (hydrothermal synthesis of mesoporous silica KIT-6 temperature was 130 °C) was employed as the hard template, the coupled sub-framework Cu-doped CeO2 catalyst formed. Compared with the coupled sub-framework Cu-doped CeO2 catalyst, the uncoupled sub-framework Cu-doped CeO2 catalyst has the higher surface areas and more open system. The Cu-doped CeO2 catalyst with KIT-6-50 as a template exhibited the highest catalytic activity, and complete conversion temperature (T100) was about 53 °C for CO oxidation. Besides, it was investigated that there were more chemisorbed oxygen and oxygen vacancy on the surface of Cu-doped CeO2 with KIT-6-50 as a template catalyst by XPS analysis. It could be concluded that the higher surface area and more open system was relatively conducive to the catalytic oxidation of CO. At the same time, the chemisorbed oxygen and oxygen vacancy also played an important role in CO catalytic oxidation.

•The surface area of carbon sphere had an obvious increase by adding surfactants.•PdO2 was the main active species on the surface of catalysts.•Amorphous FeO(OH) was more helpful for CO oxidation.•Surface adsorbed oxygen concentration was important for the catalytic activity.In this paper, a series of CSs (CSs was the abbreviation of carbon sphere) was synthesized by surfactants-assisted hydrothermal method, and these CSs were used as support to load metal active species for low-temperature oxidation of CO. By adjusting surfactant type and content, hydrothermal time and temperature, the optimal prepared condition of catalyst were achieved: polyvinylpyrrolidone (PVP) content = 3%, hydrothermal time = 7 h, and hydrothermal temperature = 180 °C. Contrasted Pd-Fe/CSs catalyst with Pd-Fe/CSs-PVP-S (Pd-Fe/CSs-PVP-S was abbreviation for the optimal catalyst) catalyst, it was discovered that CSs-PVP-S owned smaller particle size and higher surface area than CSs. The surface of Pd-Fe/CSs-PVP-S catalyst had rich active oxygen species, more FeO(OH) species and more tetravalent Pd species than the Pd-Fe/CSs catalyst, which vividly demonstrated that the Pd-Fe/CSs-PVP-S catalyst displayed superior activity than Pd-Fe/CSs.

Transition metal (Co, Cu, Fe)-doped CeO2 catalysts with three-dimensional mesoporous channels had been synthesized through a nanocasting route using three-dimensional mesoporous silica KIT-6 as the template. All four catalysts exhibited high surface area (>120 m2 g−1) and ordered mesopore. The research results showed that Co3O4, CuO, Fe2O3 crystallites in catalysts were encapsulated by nanosized CeO2, respectively, and a small fraction of Co, Cu, Fe ions were exposing on the surface and strongly interacting with CeO2. These ions (Co, Cu, Fe) maximized interaction with Ce ion in three-dimensional mesoporous structure, resulting in unique redox properties. The research results showed that the introduction of promoter (Co, Cu and Fe species) could effectively enhance the chemisorbed oxygen and oxygen vacancy concentration on the surface of metal-doped CeO2 catalysts. Compared with Co and Fe species, the Cu species had an obvious enhancement. The characteristic was relatively conducive to the catalytic oxidation of CO. The catalysts were evaluated for the catalytic oxidation CO reaction. The Cu-doped CeO2 catalyst exhibited the highest catalytic activity, and complete conversion temperature (T100) was about 50 °C for CO oxidation.

In this paper, three kinds of CeO2 nano-materials with different pore structures, i.e., mesoporous, microporous and nanoparticle CeO2, were synthesized. Mesoporous CeO2 (meso-CeO2) and microporous CeO2 (micro-CeO2) were prepared by adopting the mesoporous silica KIT-6 and microporous high silica ZSM-5 (Si/Al = 344.1) as templates, respectively. CeO2 nanoparticles (nano-CeO2) were synthesized by precipitation method. The palladium loaded meso-CeO2, micro-CeO2 and nano-CeO2 supports were evaluated for their catalytic activity in the CO oxidation reaction. The Pd/meso-CeO2 exhibited the highest catalytic activity, and the complete conversion temperature (T100) was about 50 °C for the CO oxidation. According to the analysis, the meso-CeO2 support has a mesoporous structure, large BET surface area and small particle size. At the same time, the Pd/meso-CeO2 catalyst has a large number of active surface oxygen species, Ce3+ cationic species and Pd4+ cationic species. These above characteristics of Pd/meso-CeO2 were relatively conducive to the catalytic oxidation of CO.

In this paper, a series of Pd–Fe/carbon sphere (CS) catalysts were prepared by a co-precipitation method and applied in low-temperature CO oxidation reactions. The effect of the particle sizes of carbon spheres, calcination temperatures of catalysts, Pd loadings and H2 reduction were investigated in detail. SEM and TEM characterizations of carbon spheres that were prepared by a hydrothermal method indicated non-porous structure, and the CSs surface was covered by Pd–Fe composites after the preparation of the catalyst. The XPS characterization of the catalysts showed that there were rich active oxygen species, more FeO(OH) species and more tetravalent Pd (PdO2) species on the surface of the Pd–Fe/CSs catalyst. These factors are expected be helpful for CO oxidation. When Pd loading was 1.0 wt%, the Pd–Fe/CSs (CSs were prepared by 1.0 mol L−1 glucose solution) catalyst, which was calcined at 200 °C without H2 reduction, had the highest activity.

Desilicication and dealuminzation with weak alkaline solution and acid liquor is an effective way to construct hierarchically mesoporous without damaging its crystallinity and preserving its acidity in ZSM-5 zeolites. We investigated the influence of the concentration of NaAlO2, treatment time, temperature and the concentration of HCl on the crystallinity of ZSM-5 and characterized the products with XRD, SEM, XRF, BET, NH3-TPD, etc. The results showed that the appropriate concentration of NaAlO2 solutions extract selectively silicon from the framework of the zeolites while a small portion of aluminum would patch some parts of vacancies produced by the removal of silicon, then the HCl would dealuminize to maintain the SiO2/Al2O3 ratios, which preserved the crystallinity of ZSM-5 perfectly. Furthermore, the micro-reaction activity tests displayed that the obtained products had higher catalytic than the parent zeolites because of their optimized hierarchical micro-mesoporous.

A series of rare earth zeolites Ln–ZSM-5 (Ln = La, Ce, Pr, Nd) were synthesized directly via a one-step hydrothermal method. The obtained zeolites were used as support and applied in low-temperature CO oxidation. The influence of various factors such as rare earth types, rare earth contents, particle sizes of molecular sieve, and silica alumina ratios, etc., on the catalytic activity of CO oxidation were investigated in detail. The results showed that low silica small size Ce–ZSM-5 (1 % Ce content) had the highest activity. The results also showed that Ce–ZSM-5 zeolite prepared by one-step direct synthesis was more suitable as catalytic support than ZSM-5 or Ce/ZSM-5 zeolite, prepared by impregnation of ZSM-5 with Ce.

In this paper, fluorine-containing ZSM-5 catalysts were first prepared and applied for butene catalytic cracking. Fluorinated ZSM-5 was obtained by treating the ZSM-5 zeolite with NH4F solutions at 85 °C. XRD showed that the intrinsic mordenite framework inverted structure of ZSM-5 zeolite was preserved and the corresponding crystallinity remained unchanged. The N2 adsorption/desorption measure indicated the generation of a number of new micropores. The experiment of butene catalytic cracking showed that catalytic performances can be greatly improved after fluorination treatment. The highest yield of ethylene plus propylene was obtained when the treated concentration of NH4F solution is 0.1 M.

A series of Pd/Fe-containing catalysts were successfully prepared by a polyol reduction method and applied for low temperature CO oxidation. The effect of supports, Ce introduction and pH values on low temperature CO oxidation was investigated in detailed. The results showed that Fe(OH)x was a suitable support better than FeOx. Addition of suitable Ce was beneficial to increase the catalytic activity. HR-TEM showed that Pd species which prepared by a polyol reduction method were highly dispersed. Through the research, the Pd-Ce/Fe(OH)x catalyst could completely oxidize CO at room temperature and keep excellent stability for 500 h at 40 °C when reaction pH value was 10.5.

•The synergistic effect of Pd and Ce enhances CO oxidation activity dramatically.•The high Si/Al ratio and small ZSM-5 zeolite are helpful for enhancing the activity.•Pd species enrich on the surface of ZSM-5 zeolite after Ce addition.A series of Pd–Ce supported ZSM-5 zeolite catalysts for CO oxidation at low temperature were prepared by co-impregnation method. The effect of Pd–Ce synergistic function, Ce loadings, and properties of ZSM-5 zeolite on low temperature CO catalytic oxidation was investigated in detailed. The results showed that the Pd and Ce loading on ZSM-5 zeolite support at the same time enhanced catalytic activity compared with only Pd or Ce loading on ZSM-5 zeolite support. The properties of ZSM-5 zeolite had a strong influence for CO oxidation. Through the research, the ZSM-5 zeolite with high silicon aluminum ratio and small size also was helpful for CO oxidation. Among these catalysts, the catalyst with 19 wt% Ce loading displayed the highest catalytic activity. Chemical and physical properties of catalysts were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). XRD and TEM showed that Pd species were highly dispersed on the surface of ZSM-5 zeolite, which was strongly dependent on the amounts of Ce loading and the interaction among Pd species, Ce promoter and ZSM-5 support. The addition of CeO2 improved the dispersion of Pd species over ZSM-5, and synergistic function of Pd and CeO2 enhanced the catalytic activity. XPS characterization indicated that as the addition of Ce increased, Pd species was easy to enrich on the surface of the catalyst.Download high-res image (155KB)Download full-size image

•The oxygen functional groups and structure defects was adjusted by O3 treatment.•The existed of certain moisture was helpful for CO oxidation.•The catalyst exhibited superior activity and resistance to moisture.•CO oxidation reaction pathway under dry and moisture condition was expounded.Porous carbon spheres (PCSs) were synthesized by surfactant assisted-hydrothermal method and the oxygen functional groups and structure defects of PCSs were controllably modulated by O3 treatment technology. Especially, the treated time and temperature played the significant roles in this strategy. Notably, the SEM indicated that the morphology and particle size of PCSs had not been changed basically after O3 treatment. However, the specific surface area of PCSs decreased with increasing O3 treatment time at 100 °C and increased with increasing O3 treatment temperature at 15 min. The effects of oxygen functional groups and structure defects on the activity of Pd-Ce/PCSs were tested in detail. A series of characterizations showed that particle size, the content of surface Pd4+, surface adsorption oxygen, oxygen vacancies, and structure defects obviously increased after O3 treatment. The increased content of surface Pd4+, surface adsorption oxygen, oxygen vacancies, and structure defects were advantageous to the improvement of activity, but the enlarged particle size was disadvantageous. Therefore, the O3 treatment temperature and time is vitally significant for the effective regulation of active sites of PCSs surface. Besides, the effect of moisture on CO conversion was also investigated, and the optimal catalyst showed excellent stability under moisture condition.In this paper, the surface oxygen functional groups and structure defects of porous carbon spheres was adjusted by O3 treatment. The effect of O3 treatment temperature and time, CO concentration, moisture on CO oxidation were investigated in detail. The optimization catalyst emerged superior catalytic activity and water resistance.Download full-size image

We reported a new one-pot method to synthesize Cu incorporated ZSM-5 with ethylene diamine tetraacetic acid copper disodium salt hydrate (EDTA-Cu) as copper source by a hydrothermal process. The obtained isomorphous substituted Cu-ZSM-5 exhibits more excellent reactivity for selective catalytic reduction of NOx by NH3 with long term stability than their conventional copper impregnated counterparts. The results indicate that the tetracoordinated Cu species in the ZSM-5 frameworks have superior catalytic properties than the Cu species existed outside the ZSM-5 zeolites frameworks. The novel ammonium salt complex method was used for the first time to synthesize the metal-ZSM-5 molecular sieves.The simplified synthesis process of Cu-ZSM-5 zeolites.Download high-res image (200KB)Download full-size image

The design and development of heterogeneous catalysts is very critical for the synthesis of various chemicals and fuels derived from superfluous biomass. The synthesis of biofuel 2-methylfuran typically derives from the conversion of the formyl group of biomass-derived furfural, because this process is very valuable in terms of the amelioration and remission of the environment and energy crisis. Herein, we designed a series of bifunctional catalysts formed in line with the spatial restriction strategy by anchoring copper nanoparticles (Cu NPs) on phyllosilicate-like structures to enhance copper dispersion and provide properly assembled Lewis acid sites to promote the hydrogenation and hydrogenolysis of the formyl group in furfural, and first applied them to the conversion of the formyl group with high efficiency. However, the modulation of the Cu–Si molar ratio is extremely critical to the possible reduction of metal consumption, full exploitation of the prerequisite metal sites and great improvement of activity. In this work, the catalyst with a Cu–Si molar ratio (actual value = 0.33) lower than that of the industrial catalyst (theoretical value = 1.0) exhibited higher yields of the intermediate furfuryl alcohol (yield = 83.4%) and the desired product 2-methylfuran (yield = 95.5%). More importantly, with the continuous increase of the Cu–Si molar ratio, it is discovered that Cu dispersion regularly decreased and the size of the Cu NPs sequentially increased, and the change of assembled Lewis acid sites surprisingly kept pace with the integrity of the layered structure, as revealed by a series of detailed characterization studies.

In this paper, mesoporous carbon (meso-C) with three-dimensional mesoporous channels was synthesized through a nanocasting route using three-dimensional mesoporous silica KIT-6 as the template. Mesoporous carbon wrapped Pd–Fe nanocomposite catalysts were synthesized by the co-precipitation method. The effects of the experimental conditions, such as pH value, Fe loading content and calcination temperature, on CO oxidation were studied in detail. The prepared Pd–Fe/meso-C catalysts showed excellent catalytic activity after optimizing the experimental conditions. The surface tetravalent Pd content, existing forms of Fe species, surface chemical adsorbed oxygen concentration, and pore channels of mesoporous carbon played vital roles in achieving the highest performance for the Pd–Fe/meso-C catalyst. The reaction pathway was conjectured according to the XPS analysis of the Pd–Fe/meso-C catalysts for CO oxidation, which maybe adhered to the Langmuir–Hinshelwood + redox mechanism. The effect of moisture on CO conversion was investigated, and the superior Pd–Fe/meso-C catalyst could maintain its activity beyond 12 h. This catalyst also showed excellent activity compared to the reported values in the existing literature.