The activity of Lewis (Nb2O5) and Br nsted (Amberlyst 70) acid catalysts for the cyclodehydration of xylose to furfural was studied. The nature of the acidity resulted in significant changes in the reaction mechanism....The activity of Lewis (Nb2O5) and Br nsted (Amberlyst 70) acid catalysts for the cyclodehydration of xylose to furfural was studied. The nature of the acidity resulted in significant changes in the reaction mechanism. Lewis acid sites promote the formation of xylulose, while Br nsted acid sites are required to further dehydrate the sugar to furfural. Amberlyst 70 in water/toluene at 175 ℃ showed lower activity but gave a higher furfural yield. Using N2 as the stripping agent considerably improved the furfural yield and product purity in the stripped stream. Catalyst stability was also studied.展开更多
Vapor-phase transformations of furfural over SBA-15 silica supported Ni catalysts under H<sub>2</sub> in a continuous-flow reactor at atmospheric pressure and 170°C and 230°C were investiga...Vapor-phase transformations of furfural over SBA-15 silica supported Ni catalysts under H<sub>2</sub> in a continuous-flow reactor at atmospheric pressure and 170°C and 230°C were investigated. Two different samples having Ni loadings of 5 and 20 wt% (denoted here by SBA-5Ni and SBA-20Ni, respectively) were prepared by impregnation and characterized by atomic absorption spectroscopy, N<sub>2</sub> sorption analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. Furan and furfuryl alcohol were two primary products resulting, respectively, from decarbonylation and hydrogenation of furfural. Under the conditions of the study, both reactions exhibited structure sensitivity evidenced by changes in product selectivities with variable Ni loadings. Compared with SBA-20Ni, the 5 wt% Ni catalyst showed better catalytic activity, reaching a furfural conversion of 100 mol% and a selectivity to furan of 98 mol%, after 5 h of time-on-stream at 230°C.展开更多
基金supported by funds from the Spanish Ministerio de Economíay Competitividad(CTQ‐2012‐38204‐C03‐03 and ENE2009‐12743‐C04‐03)from the Gobierno Vasco(Programa de Formación de Personal Investigador del Departamento de Educación,Universidades e Investigación)the Junta de Andalucía(P09‐FQM‐5070) for financial support
文摘The activity of Lewis (Nb2O5) and Br nsted (Amberlyst 70) acid catalysts for the cyclodehydration of xylose to furfural was studied. The nature of the acidity resulted in significant changes in the reaction mechanism. Lewis acid sites promote the formation of xylulose, while Br nsted acid sites are required to further dehydrate the sugar to furfural. Amberlyst 70 in water/toluene at 175 ℃ showed lower activity but gave a higher furfural yield. Using N2 as the stripping agent considerably improved the furfural yield and product purity in the stripped stream. Catalyst stability was also studied.
文摘Vapor-phase transformations of furfural over SBA-15 silica supported Ni catalysts under H<sub>2</sub> in a continuous-flow reactor at atmospheric pressure and 170°C and 230°C were investigated. Two different samples having Ni loadings of 5 and 20 wt% (denoted here by SBA-5Ni and SBA-20Ni, respectively) were prepared by impregnation and characterized by atomic absorption spectroscopy, N<sub>2</sub> sorption analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. Furan and furfuryl alcohol were two primary products resulting, respectively, from decarbonylation and hydrogenation of furfural. Under the conditions of the study, both reactions exhibited structure sensitivity evidenced by changes in product selectivities with variable Ni loadings. Compared with SBA-20Ni, the 5 wt% Ni catalyst showed better catalytic activity, reaching a furfural conversion of 100 mol% and a selectivity to furan of 98 mol%, after 5 h of time-on-stream at 230°C.
