A novel and efficient water/oil emulsion reactor for organosolv lignin depolymerization is presented using an ionic liquid catalyst based on the self-surfactivity of lignin. The physical–chemical properties of the emulsion reactor and lignin were intensively studied using optical photo, dynamic light scattering, surface tension measurement, and hydrophile–lipophile balance value determination. The results show that the emulsion reactor demonstrates a more significant process intensification effect on lignin depolymerization, with more than 29.60 mg g–1 desired phenolic compounds obtained, which is about 3.3 times higher than that from a reactor without emulsification. Another advantage of this water/oil emulsion reactor is that both the organic solvent (n-butanol) and the ionic liquid catalyst can be recycled easily, as the depletion of lignin surfactant at the end of depolymerization can result in the phase partition and the enrichment of final products in the oil phase automatically.

An efficient autocatalytic process for the production of 5-hydroxymethylfurfural (HMF) from fructose-based carbohydrates has been investigated without the addition of any external catalysts in a methyl isobutyl ketone/water biphasic system, leading to elevated HMF yield through continuous extraction of HMF from an aqueous solution. The results show that both the reaction temperature and time have significant effects on fructose conversion and HMF yield; 96.8% of fructose can be converted into 73.6% of HMF with a small amount of levulinic acid and formic acid formed at a point of compromise between the reaction temperature and time (160 °C for 2 h). In addition, this autocatalytic system is suitable for other fructose-based feedstocks, such as sucrose and inulin, to achieve acceptable HMF yield. Moreover, a simple and efficient purification strategy for as-prepared HMF, viz., the NaOH neutralization method, has also been tested, achieving more than 99% of HMF recovery with more than 98% of purity correspondingly.

Novel Mn–Zr mixed oxide catalysts have been prepared by the citric acid method for the low-temperature selective catalytic reduction (SCR) of NOx with ammonia in the presence of excess oxygen. They have been characterized by a series of techniques, specifically N2 adsorption–desorption, X-ray diffraction (XRD), temperature programmed reduction (TPR), temperature programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS). It was found that an Mn(0.5)–ZrOx-450 (Mn/(Mn + Zr) mole ratio of 0.5) catalyst showed the highest activity, giving 100% NOx conversion at 100 °C with a space velocity of 30 000 h–1. XRD results suggested that an Mn–Zr solid solution was formed in the Mn(0.5)–ZrOx-450 catalyst, with highly dispersed MnOx. TPR data indicated a strong interaction between the zirconium oxide and manganese oxide, which improved the reduction ability of the MnOx. The TPD results indicated that an appropriate NH3 adsorption ability was beneficial for the low-temperature SCR. The catalyst showed a certain level of sulfur tolerance and water resistance. The effect of H2O could be quickly eliminated after its removal, whereas deactivation by SO2 proved to be irreversible.

•Organosolv bagasse lignin is efficiently converted in cooperative IL pairs.•66.7% of lignin is depolymerized without obvious char formation at 523 K for 30 min.•IL catalyst [bSmim][HSO4] shows excellent ether linkage cleavage capability.•IL additive [bmim][CF3SO3] exhibits efficient carbocation scavenging preformation.•All structural units of lignin are degraded, whereas, H-lignin is the most flexible.Lignin has been considered as a promising sustainable feedstock for high value-added aromatic chemical production. Here, we propose a novel and efficient process for lignin depolymerization in the presence of cooperative ionic liquid pair, which affords excellent catalytic activity and char inhibition capability. Under the optimized reaction condition, 66.7% lignin conversion is achieved, yielding 14.5 wt.% phenolic monomer, numerous volatile products (identified by GC–MS) and negligible char formation. The structural evolution of the sugarcane lignin was intensively investigated via comparative characterization of raw and regenerated lignin using HSQC, 1H NMR, FT-IR, GPC and elemental analysis. All three structural lignin units are degraded in this process, where, H-lignin is found to be the most susceptible. Satisfactory lignin depolymerization performance was found for the cooperative ionic liquid system, even after the fifth run, demonstrating a reasonable reusability.Download high-res image (167KB)Download full-size image

•Zirconium phosphate is efficient and selective for γ-valerolactone (GVL) production.•The properties of the catalyst can be controlled by adjusting Zr and P contents.•Catalytic activity essentially depends on the ratio of Lewis to Brønsted acid sites.•98.1% butyl levulinate conversion is achieved with 95.7% GVL yield over ZrPO-1.00.•The catalyst shows high stability and reusability.The efficient production of γ-valerolactone (GVL) from renewable resources is attracting increasing attention in view of its wide application in fuel and synthetic chemistry. In this study, a series of novel and efficient zirconium phosphate catalysts were developed for the transfer hydrogenation of levulinate esters to GVL using isopropanol as the hydrogen donor. Experimental results show that 98.1% butyl levulinate conversion and 95.7% GVL yield can be achieved with ZrPO-1.00 at 483 K after 2.0 h. Intensive characterization of the synthesized catalysts using N2 adsorption-desorption, FT-IR, ICP-AES, XPS, NH3-TPD, Py-FTIR and XRD demonstrates that the physicochemical properties, particularly hydrophobicity, Lewis to Brønsted acid site ratio and Lewis acid site strength were subtly tuned via adjustment of the molar proportion of phosphorus to zirconium, which is responsible for excellent transfer hydrogenation activity. Furthermore, this optimized catalyst exhibits high stability and recyclability for at least ten reaction cycles. In addition, a plausible reaction pathway and catalytic mechanism are proposed.Download high-res image (200KB)Download full-size image

•Ce(12.5) possessed the highest activity at 75 °C and lower NH3 adsorption capacity.•Ceria altered the local surface structure of the catalyst, by partially blocking adsorption sites, while simultaneously altering the amount of chemisorbed surface oxygen.•Activity enhancement occurred as a result of the fast-SCR reaction.•Ce(12.5) was found to result in more stable chemisorbed N-containing species in the presence of SO2 leading to a more SO2 resistant catalyst compared to FeMnOx.Low-temperature NH3-SCR is an environmentally important reaction for the abatement of NOx from stationary sources. In recent years FeMnOx has attracted significant attention as a potential catalyst for this process, however its catalytic activity and SO2 resistance require further improvement. In this contribution FeMnOx has been modified to examine the effect of ceria on catalytic activity and SO2 resistance in the low temperature region. Preparation of catalysts via the citric acid method generate modified materials that exhibit enhanced NO turnover compared to FeMnOx. A reduction in NH3 adsorption (NH3-TPD) and a suitable ratio between NO sites (NO-TPD) and chemisorbed surface oxygen (XPS) are beneficial for the promotion of fast-SCR. A comparative SO2 resistance study of FeMnOx and Ce(12.5) showed that the latter exhibited improved stability in the presence of SO2, as indicated by the retention of pore volume (N2 adsorption) and surface composition (XPS). In-situ DRIFTS demonstrated that chemisorbed N-containing species on Ce(12.5) were much more stable in the presence of SO2 compared to FeMnOx, which resulted in the formation of significantly less metal sulphates and NH4HSO4.Download high-res image (80KB)Download full-size image

The condensation of the dilute platform biochemical from the renewable lignocellulosic cellulose depolymerization for high quality energy production has attracted increasing attention currently. In this study, we propose an efficient process for biogasoline precursor production from the furfural and ethyl levulinate through the Aldol reaction at the ambient temperature. The results show that the furfural and ethyl levulinate can be efficiently condensed with the catalyst of commercial alkalis. Under the optimized condition, 78% of the product isolated yield can be obtained in the presence of KOH. Furthermore, the final product analysis using FT-IR, GPC, 1H-NMR, 13C-NMR and elemental analysis demonstrates that it mainly composes of 3-(furan-2-yl(hydroxy)methyl)-4-oxopentanoate acid, an excellent precursor for C9 branched hydrocarbon of gasoline. Moreover, the investigation shows that the product distribution of this Aldol process is high temperature dependent, higher temperature resulting in the recondensation of the product, hence decreasing the C9 gasoline precursor selectivity.

It has long been demonstrated that KOH and ZnCl2 can be used as efficient chemical activation agents to prepare porous carbons. Herein, we develop a green activation method, that is, one-step calcium chloride (CaCl2) activation sugar cane bagasse with urea, for the preparation of nitrogen-rich porous carbons (NPCs). The nitrogen contents, specific surface areas, pore sizes, and specific capacitances of the obtained NPCs can be effectively tuned by adjusting the ratio of carbon precursor (sugar cane bagasse), nitrogen source (urea), and activation agent (CaCl2). The synthesized three-dimensional oriented and interlinked porous nitrogen-rich carbons (3D-NPCs) contain not only abundant porosities which can impose an advantage for ion buffering and accommodation, but also high nitrogen content in the carbons which can obviously increase the pseudocapacitance. Therefore, for the typical sample, obtained from pyrolysis of the mixture of sugar cane bagasse, urea, and CaCl2 in a mass ratio of 1:2:2 at 800 °C for 2 h under N2 atmosphere, shows a high specific capacitance, excellent rate capability (with 323 and 213 F g–1 at the discharge/charge current densities of 1 and 30 A g–1, respectively), and outstanding cycle performance (a negligible capacitance loss after 10 000 cycles at 5 A g–1).Keywords: Biomass waste; CaCl2 activation; Nitrogen-rich porous carbons; Porous structure; Supercapacitors

A biphasic system, consisting of methyl isobutyl ketone and H2O, has been achieved for a highly integrated one-pot catalytic transformation and delignification process of lignocellulosic biomass. Using SO3H-functionalized ionic liquids as catalysts, 85.8% of bagasse can be fractionated into 71.4% water-soluble chemicals at 76.3% lignin extraction ratio, under the optimized conditions. The practicability of this biphasic system for other typical biomass sources has also been tested with high efficiency, viz., 79.6 to 91.9% lignin extraction ratio of corncob, corn stalk, rice husk, and rice straw with 56.6 to 72.8% water-soluble chemicals yield at 64.8 to 81.3% feed conversion.Keywords: Biochemicals; Biomass; Biphasic system; Ionic liquids; Organosolv lignin

Catalytic conversion of sustainable cellulose to the value-added chemicals and high quality biofuel has been recognized as a perfect approach for the alleviation of the dependence on the non-renewable fossil resources. Previously, we successfully designed and explored novel and efficient cooperative ionic liquid pairs for this renewable material, which has advantages of high reactor efficiency than current technologies because of the dissolution and in situ catalytic decomposition mechanism. Here, the determinant of this process is further studied by the intensive investigation on the relationship between the cellulose conversion and the properties of ionic liquid catalyst and solvent. Scanning electron microscope (SEM), thermogravimetric analysis (TG) and elemental analysis were used for the comparative characterization of raw cellulose and the residues. The results demonstrate that this consecutive dissolution and in situ catalysis process is much more dependent on the dissolution capability of ionic liquid solvent, while comparatively, the effect of in situ acid catalysis is relatively insignificant.

CO2 is the single most important anthropogenic greenhouse gas, contributing ∼64% to the global radiative forcing. And the rising concentration of CO2 in the atmosphere will result in global climate change. In this study, 1-alkyl-3-methylimidazolium bromide ionic liquids (ILs) ([CnMIM]Br, n = 4, 6, 8, 10) were ship in a bottle synthesized in NaY zeolite to get [CnMIM]Br@NaY samples and applied for CO2 capture. These samples were then characterized by elemental analysis, thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and FT-Raman spectra. The results indicated that [CnMIM]Br ILs were successfully encapsulated inside NaY and the encapsulated [CnMIM]Br ILs were much more stable than their bulk analogues. And Raman spectra showed that the relative intensities of some peaks in the [CnMIM]Br@NaY samples had good relationships with the side chain length of ILs. Then the breakthrough curves were recorded to evaluate the CO2 adsorption capacity of these samples, and indicated that the highest adsorption capacity could reach up to 20.08 mL CO2 per g [C4MIM]Br@NaY. And the cyclic CO2 adsorption results also illustrated that the [CnMIM]Br@NaY samples were stable and effective with prolonged use. So these samples could be potential materials for CO2 capture.

Catalytic transformation of readily available widely distributed and renewable non-food lignocelluloses to value-added chemicals has been recognized as an efficient approach for the alleviation of the increasing energy crisis and climate change. An efficient catalytic transformation process for agricultural residual lignocelluloses in cooperative ionic liquid pairs was achieved. The promotion of the dissolution equilibrium, combined with rapid, in situ acid-catalyzed degradation of cellulose and hemicellulose, resulted in significantly greater conversion of the biomass to biochemicals and selective delignification through further comparative analyses of the raw materials, products and residues by GC-MS, GPC, FT-IR, SEM and elemental characterization.

Novel Fe–Mn mixed-oxide catalysts were prepared for the low-temperature selective catalytic reduction (SCR) of NOx with ammonia in the presence of excess oxygen. It was found that Fe(0.4)–MnOx catalyst showed the highest activity, yielding 98.8% NOx conversion and 100% selectivity of N2 at 120 °C at a space velocity of 30 000 h–1. XRD results suggested that a new crystal phase of Fe3Mn3O8 was formed in the Fe–MnOx catalysts. TPR and Raman data showed that there was a strong interaction between the iron oxide and manganese oxide, which is responsible for the formation of the active center―Fe3Mn3O8. Intensive analysis of fresh, used, and regenerated catalysts by XPS revealed that electron transfer between Fen+ and Mnn+ ions in Fe3Mn3O8 may account for the long lifetime of the Fe(0.4)–MnOx catalyst. In addition, the SCR activity was suppressed a little in the presence of SO2 and H2O, but it was reversible after their removal.

Carbon-enriched lignocelluloses are regarded as the perfect alternative for nonrenewable fossil fuel, and have a great potential to alleviate the increasing energy crisis and climate change. However, the tightly covalent structure and strong intra and inter-molecular hydrogen bonding in lignocellulose make it high recalcitrance to transformation due to the poor solubility in water or common organic solvents. Dissolution and transformation of lignocellulose and its constituents in ionic liquids have therefore attracted much attention recently due to the tunable physical-chemical properties. Here, ionic liquids with excellent dissolving capability for biomass and its ingredients were examined. The technologies for lignocellulose biorefining in the presence of ionic liquid solvents or catalysts were also summarized. Some pertinent suggestions for the future catalytic conversion and unitization of this sustained carbon-rich resource are proposed.

The sunlight is the largest single available source of clean and renewable energy to ensure human society’s sustainable development. Owing to their low production cost and high energy conversion efficiency, dye-sensitized solar cells (DSSCs) have been regarded as good alternatives to conventional photovoltaic devices. Herein, a series of composite electrolytes based on poly(ethylene oxide) (PEO) and the binary ionic liquids 1-propyl-3-methy-imidazolium iodide ([PMIm]I) and 1-ethyl-3-methylimidazolium thiocyanate ([EMIm][SCN]) were prepared and then applied to fabricate six DSSCs. The composite electrolytes were characterized by fourier transform infrared spectroscopy (FTIS), X-ray diffraction (XRD), and electrochemical impedance spectra (EIS). It was shown that the addition of binary ionic liquids would reduce the degree of crystallinity of PEO, thus improving the ionic conductivities of the electrolytes by about 2 orders of magnitude. Investigation on the photovoltaic performances of these DSSCs showed that the fill factor (FF) could reach up to 0.67 and energy conversion efficiency (η) could reach up to 4.04% under AM 1.5 full sunlight (100 mW/cm2).

A family of imidazolide ionic liquids were synthesized and characterized. These ionic liquids combined the virtues of strong basicity and relatively good thermal stability. Catalytic properties of these imidazolide ionic liquids were investigated and satisfactory yield was achieved when 2.0 mol % of [Bmim]Im was used as catalyst for aza-Markovnikov addition under solvent-free condition at room temperature in one hour. Experimental results show that a hydrogen bond is not formed between [Bmim]Im/imidazole and vinyl ester, and its existence is not necessary for the [Bmim]Im catalyzed aza-Markovnikov addition either. A possible mechanism for [Bmim]Im-catalyzed aza-Markovnikov addition was proposed. The use of imidazolide ionic liquids in aza-Michael addition was investigated as well.Imidazolide ionic liquids were synthesized and characterized. High yields of aza-Markovnikov and aza-Michael additions were achieved while 2 mol % of imidazolide ionic liquid was used as catalyst at room temperature without the utilization of any organic solvent.

Ionic liquids (ILs) possess a number of unique properties; hence they have received much interest as green media for synthesis, analysis, catalysis, separation, and energy provision. More recently, chiral ionic liquids (CILs), which are derived from natural amino acids with chirality, biodegradability, reduced toxicity, and high biocompatibility, have also attracted interest. This report provides an overview of the design, synthesis, properties, and applications of these new CILs derived from natural amino acids. This is a current area of research that is poised for rapid development and expansion.

AbstractStorage-reduction of NOX by carbon monoxide was investigated over combined catalysts of Mn/Ba/Al2O3-Pt/Ba/Al2O3. Combination of Mn/Ba/Al2O3 and Pt/Ba/Al2O3 catalysts in different ways showed excellent NOX storage-reduction performance and the content of Pt could be reduced by 50%. Not only the addition of 5Mn/15Ba/Al2Oa to lPt/15Ba/Al2Oa could improve its storage ability, but also enhance the NOX conversion consequently. NOx conversion over the combined catalysts (the combined catalysts I and II) was increased under dynamic lean-rich burn conditions, the maximum NOX conversion increased from 69.4% to respectively 78.8% and 75.7% over two combined catalysts.

Cr–Mn mixed-oxide based catalysts were prepared for the low-temperature selective catalytic reduction of NOx with ammonia in the presence of excess oxygen. It was found that the Cr(0.4)–MnOx showed the highest activity and yielded 98.5% NOx conversion at 120 °C. XRD, TPR and Raman data results suggested that a crystalline phase of CrMn1.5O4 was present in the Cr–MnOx catalysts, which contained the active species. XPS results of fresh, used and regenerated Cr(0.4)–MnOx catalysts illustrated clearly the presence of Mn2+, Mn3+, Mn4+ and Cr2+, Cr3+, Cr5+ oxidation states. Efficient electron transfer between Cr and Mn in the crystal of CrMn1.5O4 was thought to be the reason for the high activity and long lifetime of the Cr(0.4)–MnOx catalyst. In addition, the SCR activity was gradually suppressed in the presence of SO2, while such an effect was shown to be reversible after switching off the SO2 injection.Impressive activity for low-temperature SCR of NOx is achieved on novel catalysts containing CrMn1.5O4 phase, which provides catalytically active sites due to facilitated electron transfer between Cr and Mn.Download high-res image (73KB)Download full-size image

Large-scale production of isobutene from isobutane requires high-performance and cost-effective catalysts. Carbon-based nanomaterials such as carbon nanotubes have attracted great attention as substrates for decorating with functional groups or doping with heteroatoms. In this paper, oxidized multi-walled carbon nanotubes were modified with nitrogen at 900 °C and applied in direct dehydrogenation of isobutane. Upon surface oxidization and high temperature annealing, the 1.93 atom% nitrogen-doped oxidized multi-walled carbon nanotubes are found to be an effective dehydrogenation catalyst, which exhibits an isobutane conversion of 51.8% (17.4 mmol g−1 h−1), isobutene selectivity and yield of 45.9% and 23.8% (8.0 mmol g−1 h−1) respectively. The increased catalytic performance is well-correlated with enhanced adsorption strength of isobutane and reduced adsorption strength of isobutene, which relates to the presence of nitrogen species, as revealed by XPS and TPD measurements. Minimal deactivation of the catalyst, as indicated by time on stream studies, may be caused by the loss of nitrogen heteroatoms and the change in ID/IG.