Advanced Materials Research Vols. 396-398

Abstract: Cs-Zr-Mg/SiO2 can be effective catalysts for the production of methyl methacrylate (MMA) by the condensation of methyl propionate (MP) and formaldehyde (FA). The catalysts with different magnesium loading were prepared by incipient wetness impregnation. The number and strength of surface acid and base sites of catalysts were determined by stepwise temperature-programmed desorption (TPD) of NH3 and CO2, respectively. It was found that the catalyst with a magnesium loading of 1.0 g/100molSiO2 had the modest acidity and basicity and showed the excellent performance. Furthermore, it was also observed that the activity of the catalyst decreased with reaction time, and coke formed on the catalyst was characterized by DTA/TG technique after reaction.

Abstract: A series of silicon dioxide supported titania by the impregnation method for transesterification of diethyl oxalate (DEO) and phenol was carried out under the facile catalytic condition in the liquid phase at 453 k in the atmospheric pressure. Within different TiO₂ loadings ranging from 1% to 20%, 10% TiO₂/SiO₂ performed best, giving 49.5% conversion of DEO and the total 100% selectivity to ethyl phenyl oxalate (EPO) and diethyl oxalate (DPO). To further study the relationship between catalytic performances and the catalysts structure, several characterization methods, analysis of X-ray diffraction (XRD), Raman spectroscopy measurement and FTIR of adsorbed pyridine studies were utilized. The results of XRD and Raman, showed amorphous structure of TiO₂ on SiO₂ below the 10% loading and crystalline form of TiO₂ phase on SiO₂ above the 10% loading. In addition, FTIR of adsorbed pyridine studies illuminated the Lewis-type acid sites were responsible for transesterification between DEO and phenol.

Abstract: Abstract. Using MCM-41 molecular sieves as the support, Cu-ZnO/MCM-41 and Cu/MCM-41 catalysts were prepared by impregnation and grinding. The catalysts were characterized by XRD, N2 adsorption-desorption and TPR methods. The catalytic activity of the dehydrogenation of methanol to methyl formate (MF) was evaluated using the flow microreactor under atmospheric pressure. According to the results, the catalyst prepared by impregnation had a better selectivity for the MF, but a lower methanol conversion rate. However, the product's selectivity could be improved by adding ZnO additive while the methanol conversion rate was reduced. For Cu/MCM-41 prepared by impregnation and grinding, the methanol conversion rate was 20.18% and 24.13% respectively at 250°C and the MF selectivity was 73.75% and 67.35% respectively. Likewise for Cu-ZnO/MCM-41 prepared by impregnation and grinding, the methanol conversion rate was 15.28% and 18.83% respectively at 250°C and the MF selectivity was 81.31% and 75.32% respectively.

Abstract: In this work, a novel method was reported for preparation of Ru/activated carbon (Ru/AC) catalysts. Supercritical carbon dioxide (SC CO₂) was employed as medium for the impregnation of ACs with inorganometallic precursor of RuCl3. The Ru/AC catalysts displayed excellent activity for the catalytic hydrogenation of D-glucose. Selected Ru/AC catalysts were characterized by N₂ adsorption-desorption, TPR and TEM analysis. The results show that the order of effects on catalytic activity are supercritical temperature > supercritical pressure > amount of co-solvent > time of impregnation. The optimal supercritical parameters for preparing Ru/AC catalyst were 313 K, 8 MPa, 4 ml of methanol and 9 h, respectively. The highest reaction rate of hydrogenation reached 86.35 mmol•min-1g-1Ru, upgrading 42.96% compared with the activity of conventional Ru/AC prepared using aqueous impregnation. The SC CO2 impregnation could result in Ru uniformly dispersed on the outer surface and in the pore of AC, leading _{Subscript text}to higher dispersion of Ru and enhanced interaction between AC and Ru. Furthermore, the enhanced interaction induces improved reduce temperature. Consequently, the catalytic activity of Ru/AC catalysts is improved significantly.

Abstract: The shape-selective alkylation of toluene with propylene to produce p-cymene (p-isopropyltoluene) was investigated over parent zeolites and modified zeolites. The catalytic performance was compared over ZSM-5, MOR, SAPO-11, MCM-22 and β zeolite. And, their selectivity was improved by loading of metallic oxides over zeolites, and modified β zeolite showed the highest conversion of toluene and the highest selectivity of p-cymene. Moreover, the reaction conditions were optimized over the modified β zeolite.

Abstract: We have obtained relatively unambiguous evidence that validates a simple, predictive model describing the uptake of noble metal coordination complexes from aqueous solutions onto oxide surfaces. The results confirm that the metal-oxide interaction is essentially electrostatic in nature. The evidence has been obtained by applying extended x-ray absorption fine structure (EXAFS) analysis to noble metal adsorption systems in which the effect of surface-localized pH has been isolated and quantified. The model has applications ranging from catalysts preparation to heavy metal pollution abatement and precious metal recovery.

Abstract: The effect of catalyst atomic ratio on the performance of styrene selective oxidation by H2O2 as probe reaction over spinel type strontium ferrate prepared through sol-gel method was investigated. The catalyst evaluation results show that the optimum catalyst atomic ratio was n(Fe):n(Sr)= 2:1 with high catalytic activity. The catalysts were detected by XRD. The optimum calcination temperature was 700 °C. Micro-structure and essence disciplinarian of strontium ferrate were disclosed. Under normal atmospheric pressure and 0.5 g catalyst dosage conditions, the optimum feed ratio, reactive temperature and reactive time are n(H2O2):n(styrene)=1:1, 343 K and 9 h, respectively. The selectivition and yield of benzaldehyde were 65.7% and 34.3%, respectively. The technological process route possessed under ambient conditions with advantage such as excellent properties in product.

Abstract: The author chose five kinds of commercial resins for blank experiment and then added oxidants.We studied that how removal rate changed under different temperature and picked the D001-cc as the best supporter in desulfurization procedure. And heteropolyacid was supported onto D001-cc with different loadings,the results showed 30% was the optimal condition.

Abstract: Effect of copper compounds on the catalytic activity of n-Bu2SnO in the transesterification of dimethyl carbonate and phenol to diphenyl carbonate was investigated. The results showed that they as promoters could obviously enhance the activity of n-Bu2SnO except for Cu. The characterizations of X-ray diffraction (XRD) identified that CuO could be reduced to Cu, and Cu2O was stable. When the reaction was carried out between 150 and 180 oC, with molar ratio of n-Bu2SnO to Cu2O of 8:1, catalyst amount 0.0067, reaction time 10h, molar ratio of dimethyl carbonate to phenol of 3:1, the phenol conversion and the transesterification selectivity were 60.3% and 99.2%, respectively. In the transesterification, the acid-base synergistic effect between Cu2O as the basic promoter and n-Bu2SnO as the Lewis acid resulted in the active enhancement of n-Bu2SnO. Moreover the performance of Cu2O remained unchanged for seven times reuse.

Abstract: Y-Mg-Al-layered double Oxides (Y-Mg-Al-LDO) were prepared by calcining Y3+-doped Mg-Al-layered hydrotalcites at 823 K for 8 h from co-precipitation method. The samples were detected by XRD and CO2-TPD. Micro-structure and essential regularity were disclosed. The acetone condensation reaction as a probe reaction was carried on fixed-bed micro-reactor at reactive temperature 673 K, reactive time 3 h and liquid hourly space velocity (LHSV) 6 h-1 over Y-Mg-Al-LDO. The catalyst evaluation results show that Y-Mg-Al-LDO possess high catalytic activity. The maximum value of acetone conversion reached 37.53%. The selectivity and single-pass-yield of isophorone were 55.66% and 20.89%, respectively.