One-step synthesis of n-butanol from bimolecular condensation of ethanol was firstlyachieved over nickel supported gamma alumina catalyst. A mechanism of dehydration path for thegrowth of carbon chain by eliminating a...One-step synthesis of n-butanol from bimolecular condensation of ethanol was firstlyachieved over nickel supported gamma alumina catalyst. A mechanism of dehydration path for thegrowth of carbon chain by eliminating a hydroxy group from one ethanol molecule with a α-H ofother ethanol molecule rather than aldol condensation was verified.展开更多
A promising catalytic material, modified ga mma alumina with high surface area (300m2/g) and higher c ontents of strong acid sites was developed. It was prepared by a special precip itation method with aluminum nitra...A promising catalytic material, modified ga mma alumina with high surface area (300m2/g) and higher c ontents of strong acid sites was developed. It was prepared by a special precip itation method with aluminum nitrate solution containing a certain amounts of or thosilicic acid and ammonia aqueous solution. Compared with commercial gamma alu mina, the modified gamma alumina is an effective catalyst for dehydration of tet rahydrofurfuryl alcohol to 3,4-Dihydro-2H-pyran.Under the optimized reaction conditions, an improved yield of 3,4-Dihydro-2H-pyran of 93.4% was achieved. The profiles of pyridine TPD show that the modified gamma alumina exhibits more strong acid sites than that in the commercial gamma alumina, indicating the stro ng acid sites on the surface of the catalyst may play a crucial role in this rea ction.展开更多
Cobalt supported on carbon nanotubes （CNTs）-covered alumina has been recently developed and successfully utilized as a catalyst in Fischer-Tropsch synthesis （FTS）. Problems associated with shaping of Co/CNTs into ...Cobalt supported on carbon nanotubes （CNTs）-covered alumina has been recently developed and successfully utilized as a catalyst in Fischer-Tropsch synthesis （FTS）. Problems associated with shaping of Co/CNTs into extrudates or pellets as well as catalyst attrition rendered these materials unfavorable for industrial applications. In this investigation regular γ- and nano-structured （N-S） alumina as well as CNTs-covered regular γ- and N-S-alumina supports were impregnated by cobalt nitrate solution to make new cobalt-based catalysts which were also promoted by Ru. The catalysts were characterized and tested in a micro reactor to evaluate their applicability in FTS. γ-Al2O3 was prepared by calcination of bohemite and N-S-Al2O3 was prepared by sol-gel method using aluminum chloride as starting material. Catalyst evaluations indicated that N-S-Al2O3 was superior to regular γ-Al2O3 and that CNTs-covered alumina supports were favored over non-covered ones in terms of activity and heavy hydrocarbon selectivity. These were justified by porosimetric characteristics of the catalysts and existence of CNTs points of view. CNTs-covered catalysts also showed higher wax selectivity and better resistance to deactivation. Furthermore, TPR analysis indicated that the cobalt aluminate phase, which is responsible for the permanent deactivation of alumina supported Co-based catalysts, did not form on alumina supported Co-based catalysts covered with CNTs due to weaker interactions between cobalt and alumina.展开更多
文摘One-step synthesis of n-butanol from bimolecular condensation of ethanol was firstlyachieved over nickel supported gamma alumina catalyst. A mechanism of dehydration path for thegrowth of carbon chain by eliminating a hydroxy group from one ethanol molecule with a α-H ofother ethanol molecule rather than aldol condensation was verified.
文摘A promising catalytic material, modified ga mma alumina with high surface area (300m2/g) and higher c ontents of strong acid sites was developed. It was prepared by a special precip itation method with aluminum nitrate solution containing a certain amounts of or thosilicic acid and ammonia aqueous solution. Compared with commercial gamma alu mina, the modified gamma alumina is an effective catalyst for dehydration of tet rahydrofurfuryl alcohol to 3,4-Dihydro-2H-pyran.Under the optimized reaction conditions, an improved yield of 3,4-Dihydro-2H-pyran of 93.4% was achieved. The profiles of pyridine TPD show that the modified gamma alumina exhibits more strong acid sites than that in the commercial gamma alumina, indicating the stro ng acid sites on the surface of the catalyst may play a crucial role in this rea ction.
基金supported by the Research and Technology Directorate of National Iranian Oil Company
文摘Cobalt supported on carbon nanotubes （CNTs）-covered alumina has been recently developed and successfully utilized as a catalyst in Fischer-Tropsch synthesis （FTS）. Problems associated with shaping of Co/CNTs into extrudates or pellets as well as catalyst attrition rendered these materials unfavorable for industrial applications. In this investigation regular γ- and nano-structured （N-S） alumina as well as CNTs-covered regular γ- and N-S-alumina supports were impregnated by cobalt nitrate solution to make new cobalt-based catalysts which were also promoted by Ru. The catalysts were characterized and tested in a micro reactor to evaluate their applicability in FTS. γ-Al2O3 was prepared by calcination of bohemite and N-S-Al2O3 was prepared by sol-gel method using aluminum chloride as starting material. Catalyst evaluations indicated that N-S-Al2O3 was superior to regular γ-Al2O3 and that CNTs-covered alumina supports were favored over non-covered ones in terms of activity and heavy hydrocarbon selectivity. These were justified by porosimetric characteristics of the catalysts and existence of CNTs points of view. CNTs-covered catalysts also showed higher wax selectivity and better resistance to deactivation. Furthermore, TPR analysis indicated that the cobalt aluminate phase, which is responsible for the permanent deactivation of alumina supported Co-based catalysts, did not form on alumina supported Co-based catalysts covered with CNTs due to weaker interactions between cobalt and alumina.
