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1,2,4-TriMB methylation with syngas conversion over CuZnZrOx–Z5 shows over 90% durene selectivity in tetramethylbenzene, which develops a promising route for the synthesis of value-added durene.

Heterogeneous halide-free carbonylation of methanol to acetates, including methyl acetate (MA) and acetic acid, using non-precious metal catalysts has been a topic of interest for decades. The key issue is that the water produced by methanol dehydration inhibits the formation of acetyl species and reduces the MA selectivity. Here, we report that CuCeOx/H-mordenite (H-MOR) catalyst can nearly eliminate the inhibiting effect of water on carbonylation by a water-gas shift reaction (WGSR) on-site, and can thus achieve 96.5% methanol conversion with 87.4% MA selectivity for the halide-free carbonylation of methanol. The results of powder X-ray diffraction, transmission electron microscopy, and scanning electron microscopy show that the Cu and Ce species are highly dispersed on H-MOR even when the CuCeOx contents are as high as 29 wt-%. Fourier transform infrared spectroscopy and CO chemisorption analysis reveal that a small portion of Cu species can migrate into the channel of H-MOR when CuCeOx/H-MOR is calcined at 500 °C and these Cu species are converted into Cu+ sites upon reduction. The Cu+ sites facilitate the WGSR and are also active sites for methanol carbonylation. The introduction of Ce benefits the inhibition of coke deposits and thus enhances the catalyst stability.

Heterogeneously and uniformly dispersed metal nanoclusters with high thermal stability and stable nonmetallic nature show outstanding catalytic performance. In this work, we report on the role of sulfur moieties in hydrochlorination catalysis over carbon-supported gold (Au/C). A combination of experimental and theoretical analyses shows that the −SO3H and derived −SO2H sulfur species in high oxidation states at the interface between Au and −SO3H at ≥180 °C give rise to high thermal stability and catalytic activity. By contrast, the grafted thiol group (−SH) and the derived low-valence sulfur species on carbon markedly destabilize the Au nanoclusters, promoting their rapid sintering into large Au nanoparticles and leading to the loss of their cationic nature. Theoretical calculations suggest that −SO3H favorably adsorbs and stabilizes cationic Au species. Compared to Au/C and Au–SH/C with the Auα+/Au0 atomic ratios of 1.02 and 0.24, respectively (α = 1 or 3), the activity and durability of acetylene hydroc...

Tungsten carbides exhibit excellent performance in many heterogeneous processes because of their distinctive catalytic properties. Preparation of tungsten carbides with controllable phase composition relevant to their catalytic behavior is essential yet challenging. In this study, tungsten carbides embedded in carbon spheres (WxC@CS) were fabricated through carburization of organic–inorganic hybrid precursors. W1.25C@CS with rational structure-tuning properties exhibits promising regioselectivity (reaching 91.5%) toward aryl CO bond cleavage, specifically during hydrogenolysis of guaiacol to phenol. A structure reconstruction strategy was adopted to elucidate structure–performance relationship by transforming commercially available bulk WC from inert phase to composition-dependent active catalysts. Combined catalytic and characteristic analyses illustrate that the catalyst performance is dependent on the C-defect structure. The intimate connection between the phenol space time yield and the C/W atomic ratio on the exterior interface of the catalyst was verified. The C/W atomic ratio of 7.2 leads to the optimal catalytic performance. Density functional theory calculations were performed to define the catalytic mechanism at the atomic level. The theoretical analysis suggests an appropriate configuration of surface W and C atoms for activation of hydrogen and guaiacol molecules, rendering the intrinsic active sites for phenol production. This work provides insights into controlling the surface compositions of tungsten carbides to develop efficient CO bond cleavage catalysts, which verifies the importance of hydrogenolysis catalysis in lignin-derived compounds involving complex O-containing guaiacols and phenolics.

Heterogeneous conversion of methanol to methyl acetate (MA) through halide-free catalysis is meaningful from academic and industrial perspectives. In this study, we developed a combined halide-free Cu-based catalyst system composed of Cu-H-MOR + CuCeO and Cu-H-MOR (labeled Cu-H-MOR + CuCeO‖Cu-H-MOR) for the heterogeneous conversion of methanol into MA in the presence of CO. Cu-H-MOR catalyzed the dehydration of methanol to dimethyl ether (DME) and subsequent carbonylation of DME to MA. CuCeO converted water from methanol dehydration into H2 and CO2 through the water-gas shift reaction (WGSR) at relatively low temperatures. The WGSR catalyst is critical to the conversion of methanol to MA in the presence of CO through halide-free catalysis. This process not only produced H2 but also eliminated significantly the influence of water on the carbonylation of DME. Results indicated that the selectivity to MA was only 14% without the WGSR catalyst but reached 90% with the WGSR catalyst. Thermal gravimetric analysis showed that the selectivity to MA began to decline gradually after the reaction on stream for 18 h because of the coke formation in the catalyst pores. The coke on the catalyst could be completely removed simply by burning without destroying the structure of the combined catalyst. The combined catalyst system Cu-H-MOR + CuCeO‖Cu-H-MOR could be recycled at least five times with negligible loss in activity and MA selectivity.

Deep hydrogenation of polycyclic aromatic hydrocarbons is an important reaction in the petroleum industry. Sintering and coking of active metal nanoparticles are major reasons for deactivation. In this study, a Ni phyllosilicate with different morphologies was synthesized by a modified hydrothermal method and used in the hydrogenation of naphthalene. The physicochemical properties of the Ni phyllosilicate were carefully examined by various characterizations. The in situ exsolution of Ni nanoparticles inlaid into Ni phyllosilicate strengthens the interaction between nanoparticles and support, thereby maintaining the size of the Ni nanoparticles during the reaction. The surface Lewis acid sites of the Ni phyllosilicate are beneficial for the adsorption of aromatic substrates and favor the deep hydrogenation of polycyclic aromatic hydrocarbons under optimal reaction conditions. Besides, the pore size distribution of the Ni phyllosilicate may have a profound effect on its performance stability. The Ni phyllos...

A series of ceria (CeO2) modified MgAl2O4 spinels were used to support silver nanoparticles (Ag/MgAl2O4-Ce) and tested for catalytic soot oxidation. This solid composition presents outstanding catalytic activity for soot oxidation, namely, initial reaction temperature, Ti = 236 °C, and temperature of maximum reaction rate, Tm = 359 °C. In contrast to Ag/MgAl2O4, the presence of CeO2 enhanced significantly the formation of superoxide and peroxide surface adsorbed oxygen species, thereby largely promoting the catalytic performance in soot oxidation. Induced by the strong interactions between Ag and CeO2, Ag/MgAl2O4-Ce displays higher Ag metal dispersion with excellent thermal stability than Ag/MgAl2O4 catalyst. This explains well the absence of deactivation for the Ag/MgAl2O4-Ce catalyst after five cycles of soot combustion.

Heterogeneous catalytic oxidation arises from the prerequisite oxygen activation and transfer ability of metal oxide catalysts. Thus, engineering intercalated nanounits and heterophase metal oxide structures, and forming interstitial catalyst supports at the nanoscale level can drastically alter the catalytic performances of metal oxides. This is particularly important for ceria-based nanomaterial catalysts, where the interactions of reducible ceria (CeO2) and nonreducible oxides are fundamental for the preparation of enhanced catalysts for oxygen-involved reactions. Herein, we intercalated nanostructured CeO2 in the bulk phase of magnesium aluminate spinel (MgAl2O4, referred to as MgAl), produced the interstitial effect between CeO2 nanoparticles and MgAl crystallites, thus boosting their oxygen transfer and activation capability. This nanoscaled intercalation engineering significantly enhanced the number and quality of tight contact points between the nanostructured CeO2 and MgAl units. Therefore, the oxygen storage/release capability (OSC) is exceptionally improved as revealed by various characterizations and catalytic carbon oxidation reaction. A mechanism similar to the Mars–van Krevelen process at the nanoscale level was invoked to explain the catalytic oxidation mechanisms. The reactive oxygen species of gaseous O2 originate formed the bulk of the as-obtained nanomaterial, where strong interactions between the CeO2 and MgAl components occured, which were subsequently released and diffused to the catalyst-interface at elevated temperatures. Silver supported on Ce–MgAl produced an approximately 4-fold higher concentration of active oxygen species than Ag/MgAl, and gives the optimum low-temperature oxidation at 229 °C. This study verifies the importance of the redox performance of ceria-spinel with enhanced OSC, which validates that the arrangement of contacts at the nanoscale can substantially boost the catalytic reactivity without varying the microscale structure and properties of spinel.

The use of Cu-based catalysts in CO2 hydrogenation to methanol (MeOH) has attracted considerable attention due to their low reaction temperature, low cost, and high activity. However, Cu nanoparticles are usually sintered under high-H2 atmosphere. The difficulty in keeping the Cu+/Cu0 ratio stable during the reaction leads to the instability of Cu-based catalysts. In this work, La oxide-doped Cu nanoparticles socketed into parent Cu phyllosilicate nanotubes (La/CuSi-NT) are synthesized by exsolution in situ under a reducing atmosphere at elevated temperatures. They are used to catalyze CO2 hydrogenation to MeOH. Catalytic results show that the La/CuSi-NT catalyst is more stable than intact CuSi-NT and Cu-based catalysts prepared via traditional methods. Among the prepared catalysts, the 0.2La/CuSi-NT catalyst with the La/Cu molar ratio of 0.2 exhibits the highest MeOH yield of up to 428 mg gcat−1 h−1 and performance that remains stable for at least 200 h. Characteristic studies indicate that introducing a La promoter helps increase Cu+/Cu0 ratios and confirm that LaOx species favor generating the formate species of CO2 hydrogenation. Therefore, MeOH synthesis through CO2 hydrogenation is intensified over the La/CuSi-NT catalyst.

The addition of yttrium chloride (YCl3) to an activated carbon-supported Au catalyst (Au/AC) can markedly promote the catalytic performance of acetylene hydrochlorination to the vinyl chloride monomer (VCM). The structure and physicochemical features of the YCl3-modified catalysts (Y–Au/AC) were measured by X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction, C2H2-temperature programmed desorption, and scanning transmission electron microscopy. The presence of YCl3 was found suppressing the reduction of highly oxidized Auδ+ (δ = 1, 3) to metallic Au0 dependently and thus retard the agglomeration of Au nanoparticles during the reaction. In addition, the additive of YCl3 to the Au/AC catalyst greatly inhibits the coke deposition on the catalyst surface. The optimized catalyst with an atomic ratio of Y/Au = 5 (1 wt% Au loading weight) yields an 87.8% acetylene conversion and almost 100% selectivity for VCM under the reaction of GHSV(C2H2) = 800 h−1 at 180 °C. The durability test indicates that the 5Y–1Au/AC catalyst maintains high catalytic activity for more than 2300 h at 30 h−1 GHSV(C2H2) and 180 °C, indicating great promise as a non-mercury catalyst for PVC manufacture.

Silver nanoparticles supported on nitrogen-doped activated carbon (Ag/AC-N) are demonstrated as promising catalysts for the chemoselective hydrogenation of dimethyl oxalate to methyl glycolate. Characteristic studies by TPR, XPS, and Raman indicate that AC-N benefits the dispersion of silver nanoparticles due to the strong electronic interactions between nitrogen and silver species. The optimized Ag/AC-N catalyst shows intensified performance in terms of high activity and excellent stability. It is inferred that the co-existence of Ag 0 and Ag + derived from the strong interactions of nitrogen with Ag species renders the superior catalytic performance of Ag/AC-N.

CO2 hydrogenation coupled with toluene methylation can markedly enhance the production of high value-added para-xylene., Toluene methylation with methanol to produce xylene has been widely investigated. A simultaneous side reaction of methanol-to-olefin over zeolites is hard to avoid, resulting in an unsatisfactory methylation efficiency. Here, CO2 and H2 replace methanol in toluene methylation over a class of ZnZrOx–ZSM-5 (ZZO-Z5) dual-functional catalysts. Results demonstrate that the reactive methylation species (H3CO*; * represents a surface species) are generated more easily by CO2 hydrogenation than by methanol dehydrogenation. Catalytic performance tests on a fixed-bed reactor show that 92.4% xylene selectivity in CO-free products and 70.8% para-xylene selectivity in xylene are obtained on each optimized catalyst. Isotope effects of H2/D2 and CO2/13CO2 indicate that xylene product is substantially generated from toluene methylation rather than disproportionation. A mechanism involving generation of reactive methylation species on ZZO by CO2 hydrogenation and migration of the methylation species to Z5 pore for the toluene methylation to form xylene is proposed.

Copper nanoparticles exsoluted in situ under a reducing atmosphere at elevated temperatures are socketed into the parent copper phyllosilicate nanotubes and exhibit excellent catalytic performance and superior stability for the selective hydrogenation of various esters to alcohols.

Cux Fey/SiO2 catalysts were prepared using urea-assisted sol−gel method. The structure and physicochemical properties of the catalysts were characterized using N2 adsorption–desorption, transmission electron microscopy, H2-temperature-programmed reduction, powder X-ray diffraction, and X-ray photoelectron spectroscopy. Compared with monometallic Cu or Fe catalysts, the bimetallic Cux Fey/SiO2 catalysts exhibited enhanced catalytic performance for the selective hydrogenation of diethyl malonate to 1,3-propanediol. The bimetallic catalyst with an optimal Cu/Fe atomic ratio of 2 exhibited the highest activity, which yielded 96.3% conversion to diethyl malonate and 93.3% selectivity to 1,3-propanediol under the optimal reaction conditions. Characterization results revealed that interactions between Cu and Fe contributed to the improvement of diethyl malonate conversion and selectivity to 1,3-propanediol. The X-ray photoelectron spectroscopy results revealed that the addition of appropriate amount of Fe species enhanced the reduction of Cu2+ species, thereby increasing the Cu0 species on the surface of bimetallic catalyst. It led to a better chemisorption capacity of hydrogen and further promoted of the activation of hydrogen molecule. The ethyl acetate temperature-programmed desorption results indicated that the FeOx species provided the additional adsorption sites for substrate molecules, and they activated the C O bond. The improved catalytic performance of bimetallic Cux Fey/SiO2 catalyst was mainly attributed to the synergistic effect between Cu0 and FeOx species.

Surfactant-free bimetallic Ni@Ag nanoparticles in mesoporous silica, SBA-15 prepared by simple wet co-impregnation catalyse hydrogenation of dimethyl oxalate to methyl glycolate or ethylene glycol in high yield.

Mesoporous silica SBA-15-supported bimetallic silver–nickel catalysts (Ag–Ni/SBA-15) were prepared by a co-impregnation method for the chemoselective hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG). The structure and physicochemical properties of the catalysts were characterized using N 2 adsorption–desorption, X-ray fluorescence spectroscopy, transmission electron microscopy, H 2 -temperature-programmed reduction, UV–vis light diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, fourier-transform infrared spectroscopy and ester temperature-programed desorption. Compared with monometallic Ag or Ni catalyst, the bimetallic Ag–Ni/SBA-15 catalysts exhibited enhanced catalytic performance for the chemoselective hydrogenation of DMO to MG. The optimized Ag–Ni/SBA-15 catalyst with a Ni/Ag atomic ratio of 0.2 presented the highest MG yield and excellent catalytic stability during the hydrogenation of DMO to MG for longer than 140 h. The characterization results suggested that the Ag and Ni bimetallic nanoparticles on the catalyst surfaces likely formed a segregation structure with more Ni species in the core and more Ag in the shell, and electron transfer from Ni to Ag possibly occurred. The interactions between the Ag and Ni species generated more active/adsorption sites and prevented the transmigration of bimetallic nanoparticles during hydrogenation.

a b s t r a c t Ordered mesoporous FeSBA-15-supported Ru catalysts are characterized by N2 adsorption–desorption isotherm, H2-temperature-programmed reduction, X-ray fluorescence, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy analyses. Results suggest the co-existence of Fe oxide species highly dispersed in the frameworks of SBA-15 and Ru–Fe bimetallic nanoparticles. The concentration of Fe species is low and in the form of Ru–Fe alloys located on the catalyst surfaces following reduction pretreatment in 5% H2–95% N2 flow at 623 K for 4 h. The as-reduced Ru/FeSBA-15 catalysts efficiently and selectively hydrogenolyze short-chain carboxylic acids (e.g., acetic acid, propionic acid, butyric acid, levulinic acid, and lactic acid) to their corresponding alcoholic chemicals. Results indicate that 2% Ru/FeSBA-15 catalyst with 1.07% Fe content yields the highest performance and excellent stability, yielding 92.5% conversion of acetic acid and 85.2% selectivity to ethanol under optimized conditions. The improved catalytic performance of the FeSBA-15-supported Ru catalyst is mainly attributed to the coherent interactions between Fe and Ru species, as well as to the high dispersion of Fe oxides in the SBA-15 framework. © 2014 Elsevier B.V. All rights reserved.

Heterogeneous catalytic oxidation arises from the prerequisite oxygen activation and transfer ability of metal oxide catalysts. Thus, engineering intercalated nanounits and heterophase metal oxide structures, and forming interstitial catalyst supports at the nanoscale level can drastically alter the catalytic performances of metal oxides. This is particularly important for ceria-based nanomaterial catalysts, where the interactions of reducible ceria (CeO

Evenly dispersed tungsten carbides with controlled phase compositions that exhibit an impressive capacity to carry out the regioselective hydrogenolysis of inert aryl ether C–O bonds instead of aliphatic C–O bonds to produce aromatic compounds are reported.

A novel ruthenium complex binding to two subtly different aminophosphine ligands, (o-PPh2C6H4CH2NH2)(o-PPh2C6H4NH2)RuCl2, was successfully isolated. This bis(aminophosphine)–ruthenium complex shows efficient activity in both dimethyl oxalate (DMO) and methyl benzoate (MB) hydrogenation. On the contrast, similar complexes (o-PPh2C6H4NH2)2RuCl2 and (o-PPh2C6H4CH2NH2)2RuCl2, can only effectively catalyze the hydrogenation of DMO and MB, respectively. Our experimental studies in combination of theoretical calculations reveal that the remarkable substrate selectivity in the hydrogenation of esters arises from the nonbonding interactions operated by the CH2 linkage of the ligand.

A series of polyvinylpyrrolidone-stabilized heteropolyacids (PVP-HPAs) are generated by self-assembly of HPAs and PVP in methanol. The PVP-HPAs are then employed as catalysts for the synthesis of poly(oxymethylene) dimethyl ethers (DMM n , n⩾1) by the methanolysis of trioxane. The results suggest that the acidity of PVP-HPAs is tunable by changing the ratio of PVP and HPAs, which is a key factor for the selectivity of the DMM n product. By optimizing the composition and reaction conditions, two types of PVP-HPA, PVP-phosphotungstic acid (PVP-HPW) in a PVP/HPW ratio of 1/4:1 and PVP-silicotungstic acid (PVP-HSiW) in a PVP/HSiW ratio of 1/4:3/4, respectively afford 52.4% and 50.3% yields of DMM2–5. The optimized catalysts are reusable for a minimum of 10 times without a significant drop in performance.

Supported bimetallic Ru–Fe catalysts were prepared using a step-deposition–reduction method. The selective hydrogenolysis of acetic acid to ethanol was investigated as a reaction, which is considered to be related to the transformation of biomass-derived carboxylic acids to fuels and value-added chemicals. An SBA-15-supported Ru–Fe catalyst displayed significant improvements in catalytic performance for the hydrogenolysis of acetic acid to ethanol compared with monometallic catalysts and that with SiO2 as a carrier. When the Ru/Fe atomic ratio was set at 2/1, the prepared catalyst could give a nearly 100% conversion of acetic acid and 88% selectivity to ethanol. The catalyst showed considerable stability in terms of structure and performance for a long-term run on stream. Characterization results indicated that a small portion of Fe species was alloyed with Ru, whereas the other portion of Fe species, likely FeO1+x (0 < x < 0.5), was dispersed on the catalyst surfaces. The Fe species were crucial for the stabilization of Ru–Fe bimetallic nanoparticles and activation of acetic acid molecules in the hydrogenolysis reaction. Moreover, several other carboxylic acids, such as propionic acid, levulinic acid, and lactic acid, could also be efficiently converted to their corresponding alcoholic chemicals or lactone using the optimized Ru–Fe/SBA-15 catalyst under relatively mild conditions.

Polyvinylpyrrolidone-stabilized heteropolyacids (PVP–HPAs) are synthesized by self-assembling in alcohol. The structure of PVP–HPAs is determined by various characteristic techniques. HPAs can protonate PVP to form polymeric cations. In turn, the protonated PVP interacts strongly with the heteropolyanion by forming an ionic liquid (IL)-like structure. The self-assembling separation and recyclability characteristics are related to the PVP's IL-like structure. The catalyzing performance of PVP–HPAs varies with the species of HPA and the content of PVP. The optimized PVP–H4SiW12O40·5H2O (HSiW) (1/5:3/4) gives more than 60% conversion of cellulose and complete conversion of highly selective cellobiose into butylglucosides. The optimized PVP–HSiW is separated directly by centrifugation and retains the activity without any post-treatment during recycling. The deactivation of PVP–HPAs is related to the loss of the catalyst during recycling. The functional mechanism of the IL-like structure is explored in this control experiment.

MOST of China [2011CBA00508]; NSFC [20923004, 21173175]; Research Fund for the Doctoral Program of Higher Education [20110121130002]; Program for Changjiang Scholars and Innovative Research Team in University [IRT1036]

In this study, the effects of copper (Cu) additive on the catalytic performance of Ag/SBA-15 in complete soot combustion were investigated. The soot combustion performance of bimetallic Ag-Cu/SBA-15 catalysts was higher than that of monometallic Ag and Cu catalysts. The optimum catalytic performance was acquired with the 5Ag1-Cu0.1/SBA-15 catalyst, on which the soot combustion starts at Tig=225°C with a T50=285°C. The temperature for 50% of soot combustion was lower than that of conventional Ag-based catalysts to more than 50°C (Aneggi et al., 2009). Physicochemical characterizations of the catalysts indicated that addition of Cu into Ag could form smaller bimetallic Ag-Cu nanolloy particles, downsizing the mean particle size from 3.7nm in monometallic catalyst to 2.6nm in bimetallic Ag-Cu catalyst. Further experiments revealed that Ag and Cu species elicited synergistic effects, subsequently increasing the content of surface active oxygen species. As a result, the structure modifications of Ag by the addition of Cu strongly intensified the catalytic performance.

National Basic Research Program of China [2011CBA00508]; National Natural Science Foundation of China [20873108, 20923004]; Key Scientific Project of Fujian Province [2009HZ0002-1]

A series of supported Ru catalysts with achiral modifier triphenylphosphine (TPP) and chiral modifier (1R,2R)-1,2-diphenylethylenediamine [(1R,2R)-DPEN] were employed for the asymmetric hydrogenation of aromatic ketones. The textural and structural properties of the catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, N2 physisorption, transmission electron microscopy, CO2 and NH3 temperature-programmed desorptions, inductively coupled plasma atomic emission spectrometry, and ultraviolet−visible spectroscopy. Studies revealed that the enantiomeric excess (ee) followed this order according to the oxide supports used: MgO > γ-Al2O3 > CeO2 ≫ ZnO > SiO2, which was correlated with their surface basicity. Moreover, the highest ee value and intrinsic activity for the asymmetric hydrogenation of acetophenone were attained over the catalyst with a mean Ru nanoparticle diameter of 4.4 nm, while those for the asymmetric hydrogenation of 1-acetonaphthone were obtained over a catalyst w...

NSFC [20433030, 20873108]; 973 program [2009CB939804]; NSF of Fujian Province [2007 J0013]; Key Science & Technology Specific Project of Fujian Province [2009HZ10102]

Asymmetric hydrogenation of dimethyl itaconate by the chiral rhodium complex ligated with water-soluble sulfonated (R)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (labeled as (R)-BINAPS) was performed in ionic liquid-isopropanol biphasic catalytic system. A moderate enantiomeric excess (ee) of 64% and initial turnover frequency (TOFmax) as high as 1234 h−1 could be obtained at 303 K and 2.0 MPa when the molar ration of substrate to rhodium was set at 1000. Application of imidazolium ionic liquid [bmim]BF4 (bmim = 1-butyl-3-methyl imidazolium cation) made it possible to reuse the catalyst several times, showing rather good stability in the catalyst performance. According to the ICP-OES analyses, the total extraction of rhodium species by the reactants from the ionic liquid phase was about 3.24 wt% after the catalyst for four runs, which was about three times lower than that of total loss of phosphorous species. The slight decreases in the ee value and TOFmax during the catalyst reuse could be recovered essentially to the pristine levels by replenishing certain amount of the fresh ligand into the used catalyst.

Several cationic monoether-functionalized ionic liquids (MEF-ILs) with different substituents were synthesized and used as media for kinetic resolution of secondary alcohols catalyzed by several lipases. The results indicate that Novozym 435 (an immobilized Candida antarctica Lipase B) had higher efficiency compared to other lipases in deracemization. The alkyl substituents at the 2- and 3-positions in the imidazolium ring of MEF-ILs were found to contribute to the increased enantioselectivity and enhancement of the reaction rate, respectively, while the higher stereo-hindrance of ether bonds decreased the activity. An enantioselectivity higher than 99% with 50% conversion of rac-1-phenylethanol was achieved using the catalyst system comprised of Novozym 435 and the MEF-IL 1-(3-ethoxypropyl)-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide. The catalytic system could be separated and reused without considerable activity loss. MEF-ILs can be a new class of enzyme-benign media suitable for lipase-catalyzed kinetic resolution of secondary alcohols.

Several lactam-based Bronsted-acidic ionic liquids with different acidities were synthesized and applied to the esterification of carboxylic acids with alcohols. High conversion and perfect selectivity were obtained under mild conditions. Among the ionic liquids investigated, those having a methyl sulfonate anion (which has weaker acidity than those with a tetrafluoroborate anion) afforded the highest activity for esterification. The results indicated that the acidity and immiscibility of Bronsted-acidic ionic liquids has a synergistic effect on their esterification performance. Furthermore, after removal of water under vacuum, such ionic liquids could be reused several times without substantial loss of activity.