Preparation of Cu/SiO2 catalysts with and without tartaric acid as template via a sol-gel process Characterization and evaluation in the methanol partial oxidation

摘要

Cu/SiO2 catalysts were prepared via a sol-gel process in the presence and absence of a hydroxy-carboxylic acid(tartaric acid)as a non-surfactant template or pore-forming agent.These catalysts were characterized by means of nitrogen sorption,X-ray diffraction,Fourier transformed infrared spectrometry,thermal gravimetric analysis,temperature programmed reduction,N2O dissociative chemisorption,and transmission electron microscopy.They were evaluated in the partial oxidation of methanol(POM).The addition of tartaric acid showed two major and opposite effects on the final catalyst.On the one hand,tartaric acid has the ability to increase the pore size and specific surface area generating a mesoporous material without long-range ordering channel arrangements.On the other hand,the presence of tartaric acid contributes to decreasing the copper dispersion by aggregation of Cu species.The catalyst prepared in the presence of TA was much more active in POM than that prepared in the absence of TA.However,the last one showed a higher yield to hydrogen(Y_(H_2)approx= 49%)with a very good selectivity(S_(H_2)approx= 99%).