The production of chemicals or fuels from renewable biomass resources especially cellulose has attracted much attention because of the worldwide demand for less dependence on fossil resources.However,the direct utilization of cellulose is still a challenge because of its robust crystalline structure.Herein,the hydrogenation of cellobiose,a typical cellulose,over carbon nanotube supported ruthenium catalyst (Ru/CNT) was reported.The mechanism of cellobiose conversion was proposed and the kinetic equation was obtained.Based on the kinetic experiments carried out in the range 120—185℃ under 5.0 MPa H2,the reaction rate constants and activation energies of each reaction step in cellobiose hydrogenation were obtained with MATLAB,in which the activation energy for hydrolysis and hydrogenolysis of cellobiose was estimated as 147.1 kJ·mol-1 and 71.2 kJ·mol-1,respectively.The obtained kinetic model and some general rules on the catalytic hydrogenation of cellobiose may provide important data for efficient utilization of cellulose.
Selective oxidation or oxidative functionalization of methane and ethane by both homogeneous and heterogeneous catalysis is presented concerning: (1) selective oxidation of methane and ethane to organic oxygenates by hydrogen peroxide in a water medium in the presence of homogeneous osmium catalysts, (2) selective oxidation of methane to formaldehyde over highly dispersed iron and copper heterogeneous catalysts, (3) selective oxidation of ethane to acetaldehyde and formaldehyde over supported molybdenum catalysts, and (4) oxidative carbonylation of methane to methyl acetate over heterogeneous catalysts containing dual sites of rhodium and iron.
FeOx-SiO2 catalysts prepared by a sol-gel method were studied for the selective oxidation of methane by oxygen.A single-pass formaldehyde yield of 2.0% was obtained over the FeOx-SiO2 with an iron content of 0.5 wt% at 898 K.This 0.5 wt% FeOx-SiO2 catalyst demonstrated significantly higher catalytic performances than the 0.5 wt% FeOx/SiO2 prepared by an impregnation method.The correlation between the catalytic performances and the characterizations with UV-Vis and H2-TPR suggested that the higher dispersion of iron species in the catalyst prepared by the sol-gel method was responsible for its higher catalytic activity for formaldehyde formation.The modification of the FeOx-SiO2 by phosphorus enhanced the formaldehyde selectivity,and a single-pass formaldehyde yield of 2.4% could be attained over a P-FeOx-SiO2 catalyst(P/Fe = 0.5) at 898 K.Raman spectroscopic measurements indicated the formation of FePO4 nanoclusters in this catalyst,which were more selective toward formaldehyde formation.
