Wanchun Zhu

Graphite oxide-supported CaO catalysts for transesterification of soybean oil with methanol.

Graphite oxide (GO) supported CaO catalysts were prepared and successfully applied to the transesterification of soybean oil with methanol. The supports and resultant catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), N(2) adsorption, thermogravimetry (TG), X-ray photoelectron spectroscopy (XPS), temperature-programed desorption (TPD) and Fourier-transform infrared spectroscopy (FT-IR). The GO supported CaO catalysts exhibited excellent catalytic activity and were easily regenerated by simple heat-treatment. The oxygen-containing groups (i.e., hydroxyl, epoxide groups and carboxyl groups) present on the surface of GO likely act as anchoring centers for CaO. This work demonstrates that graphite oxide is an effective host material of catalytically active CaO nanoparticles for the transesterification of soybean oil with methanol to produce biodiesel.

Characterization of Cu-ZnO-Cr2O3/SiO2 catalysts and application to dehydrogenation of 2-butanol to 2-butanone

The Cu-ZnO-Cr2O3/SiO2 catalysts were prepared by impregnation method, which exhibited high activity for the dehydrogenation of 2-butanol to 2-butanone. These catalysts were characterized by means of XRD, EPR and BET. The experimental results indicated that (i) the valence states of copper play a key role, (ii) groups of copper atoms were the main active sites in this reaction, and (iii) copper oxide would lead to the condensation product of 5-methyl-3-heptanone.

Side-chain alkylation of toluene with methanol over boron phosphate modified cesium ion-exchanged zeolite X catalysts

A series of boron phosphate (BPO4) modified ion-exchanged CsX zeolites, prepared by impregnation method, were characterized by a variety of means and utilized as catalysts for the side-chain alkylation of toluene with methanol. Both BPO4 and Cs species are highly dispersed on the surface/channel of the BPO4/CsX zeolites. The addition of a small amount of BPO4 has no obvious effect on the basic strength of catalysts, but decreases the number of basic sites slightly. Meanwhile, more weak Lewis acidic sites appear with the increasing BPO4 loading. Compared with CsX, the BPO4 modified CsX catalysts exhibit lower ability for the adsorption/activation of methanol to produce surface intermediates like formaldehyde, unidentate formate and bidentate formate. Catalytic reaction results showed that modification of CsX with boron phosphate can improve both the conversion of toluene and the selectivity of styrene. The inhibition role in producing the unfavorable bidentate formate might be a key factor for finally resulting in the improvement of the catalytic properties of BPO4/CsX catalysts for the side-chain alkylation of toluene with methanol.

Synthesis, characterization and catalytic properties of MCM-36 pillared via the MCM-56 precursor

Pillared layered MCM-36 zeolite (MCM-36-I) was successfully synthesized from MCM-56 precursor with polymeric silica as the pillaring agent. The structure and properties of the sample was characterized by means of N2 adsorption, XRD, TEM and IR spectroscopy of pyridine adsorption. The results showed that MCM-36-I has higher external surface area and more Brönsted acidic sites on external surface than that on the MCM-36 sample (MCM-36-II) which was synthesized from layered MCM-22 precursor. The catalytic properties of these samples were tested for alkylation of benzene with isopropanol. Compared with MCM-36-II catalyst, MCM-36-I showed higher conversion of benzene and selectivity to cumene. This should be mainly assigned to the fact that MCM-36-I possesses larger amount of accessible Brönsted acid sites which located on the external surface than that of MCM-36-II.

The direct transformation of ethanol to ethyl acetate over Cu/SiO 2 catalysts that contain copper phyllosilicate

AbstractCu/SiO2 catalysts that contain copper phyllosilicate, were successfully prepared using the ammonia-evaporation method. The catalysts were characterized via XRD, ICP, BET, FTIR, TPR, XPS, NH3-TPD and FTIR of Pyridine Adsorption techniques. The results demonstrated that the formation of the copper phyllosilicate species significantly affected the structural properties and caused the CuO nanoparticles to become highly dispersed, and the copper phyllosilicate would provide access to the Lewis acidic Cu+ species. It was found that the catalyst with a 23.7 wt% copper loading exhibited the best ethanol conversion and ethyl acetate selectivity. When compared to a catalyst with the same copper loading which was prepared with the impregnation method, the higher activity and selectivity of catalysts might be ascribed to the homogenous distribution of copper nanoparticles, which was the active site for the dehydrogenation, and the amount of Lewis acidic Cu+ sites active for esterification. The synergetic effect between the Cu0 and Lewis acidic sites was the key factor to achieve direct transformation of ethanol to ethyl acetate. Graphical AbstractCu/SiO2 catalysts, which contain copper phyllosilicate, were successfully prepared using the ammonia-evaporation method. Copper phyllosilicate species caused the CuO nanoparticles to become highly dispersed, and they would provide access to the Lewis acidic Cu+ species. Synergetic effect between Cu0 and Lewis acidic sites was the key factor for the reaction.

Preparation of Nanoporous Carbon Using an Aluminophosphate Framework Template

Different organic compounds, o-dihydroxybenzene, m-dihydroxybenzene, p-dihydroxybenzene, glycol, and cyclohexylamine, were used as the extra carbon source for a series of nanoporous carbon (NC) materials prepared by directly carbonizing composites containing citric acid and aluminum phosphate. The effect of the extra carbon source was studied. The structure and surface functional groups on the NC material were different with different extra carbon sources. The NC materials prepared using m-dihydroxybenzene, p-dihydroxybenzene or cyclohexylamine have excellent catalytic activity for the aerobic oxidation of benzyl alcohol to benzaldehyde.

Transformation of Ethanol to Ethyl Acetate over Cu/SiO2 Catalysts Modified by ZrO2

Direct transformation of ethanol to ethyl acetate was investigated on a series of Cu(ZrO2)/SiO2 catalysts. Inductively coupled plasma(ICP), surface area analysis, X-ray diffraction(XRD), H2-temperature programmed reduction(H2-TPR), X-ray photoelectron spectroscopy(XPS), NH3-temperature programmed desorption(NH3-TPD) and Fourier transform-infrared spectroscopy(FTIR) techniques were used to characterize the catalysts. The results reveal that ZrO2 can improve the dispersion of copper species and increase the acidity of the Cu(ZrO2)/SiO2 catalysts. The Cu0 is responsible for ethanol dehydrogenation to acetaldehyde, and both the Lewis acid and Brønsted acid sites were in favor of the selectivity to ethyl acetate. The synergistic effect of Cu0 and an appropriate amount of acidic sites played an important role in the production of ethyl acetate.

Vapor phase aldol condensation of methyl acetate with formaldehyde over a Ba–La/Al2O3 catalyst: the stabilizing role of La and effect of acid–base properties

Vapor phase aldol condensation of methyl acetate with formaldehyde was studied over Ba–La/Al2O3 with different amounts of lanthanum catalysts. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption–desorption, pyridine absorption performed via Fourier transform infrared spectroscope (Py-IR), NH3 and CO2 temperature-programmed desorption (NH3 and CO2-TPD), thermal analysis (TG-DTA) and scanning electron microscopy (SEM). The catalytic performance was evaluated using a fixed-bed microreactor. The results showed that bare Al2O3 was intrinsically active but poorly selective to methyl acrylate. The addition of barium species significantly improved the catalytic activity and selectivity. However, the Ba/Al2O3 catalyst was not stable in the continuous reaction due to a large amount of carbon deposition on the catalyst surface. Compared with adding individual components (BaO), the combination of the two promoters (BaO and La2O3) showed higher catalytic stability. Although the activity of the Ba–La/Al2O3 catalyst was not obviously increased compared with the Ba/Al2O3 catalyst, the carbon deposition was obviously suppressed in the target reaction due to the alkaline function of La2O3. Combined with the characterization results, we found that the addition of lanthanum species could significantly reduce the number of strong acid sites on the catalyst surface, inhibit the generation of carbon species in the reaction process, and stabilize the catalytic activity of the catalyst. In addition, the lifetime of the optimum 5Ba–0.5La/Al2O3 catalyst was evaluated over a continuous period of 300 h, and the initial catalytical activity did not exhibit an obvious decrease.

Synthesis and characterization of Ce-SBA-15 supported cesium catalysts and their catalytic performance for synthesizing methyl acrylate

A series of Ce-SBA-15 mesoporous materials were synthesized through a direct hydrothermal method and further impregnated with different amounts of Cs. The catalysts were characterized by XRD, XPS, SEM, NH3-TPD, CO2-TPD, FT-IR and N2 adsorption–desorption isotherm analyses. The XRD and N2 adsorption–desorption isotherm results showed that the Ce successfully incorporated into the framework of SBA-15, which was favorable for the generation of mesoporous materials with high specific surface areas, large pore volumes and narrow pore size distribution. The incorporation of Ce changed the acid–base properties of the support and promoted the dispersion of Cs species. NH3–CO2 TPD results indicated that a number of medium-strong acid and base sites existed in the 10Cs/Ce-SBA-15(10) catalyst, which made it suitable as a catalyst for the aldol condensation of methyl acetate with formaldehyde to prepare methyl acrylate.

Catalytic amination of diethylene glycol with tertiarybutylamine over Ni–Al2O3 catalysts with different Ni/Al ratios

The catalytic amination of diethylene glycol (DEG) with tertiarybutylamine (TBA) to tertiarybutylaminoethoxyethanol (TBEE) was investigated on Ni–Al2O3 heterogeneous catalysts that were prepared using the co-precipitation method. The catalytic performances of these Ni–Al2O3 catalysts were considerably influenced by the Ni/Al ratios as well as the calcination temperature and reduction temperature of the catalysts. The catalyst with a Ni/Al ratio of 1 : 1 that was calcined at 450 °C (NiAl-1.0-450), and reduced at 550 °C, exhibited a high activity and selectivity to TBEE. Based on the characterization, the activities were due to the action of the NiAl2O4 spinel in combination with NiO, which improved the stability of Ni(0), and the presence of both acidic and basic sites in the catalysts was also indispensable for this catalytic system.