The roles of adsorbed oxygen and lattice oxygen on the surface of VPO catalyst for n butane selective oxidation were experimentally studied by using on line mass spectroscopy (MS) transient response measurement in a f...The roles of adsorbed oxygen and lattice oxygen on the surface of VPO catalyst for n butane selective oxidation were experimentally studied by using on line mass spectroscopy (MS) transient response measurement in a fixed bed micro reactor. The results showed that the lattice oxygen led to selective oxidation,while adsorbed oxygen led to deep oxidation. Gaseous oxygen could be adsorbed on the surface of the VPO catalyst and transformed to lattice oxygen but did not directly participate in selective oxidation. The diffusion of lattice oxygen from the bulk phase to the surface might be the rate controlling step of unsteady state oxidation when n butane selective oxidation and VPO catalyst re oxidation were performed separately.Increasing the diffusion rate of the lattice oxygen and usable lattice oxygen capacity in VPO catalyst could remarkably improve the reaction performance in a fixed bed reactor.展开更多
Vanadium phosphorus oxide (VPO) catalyst samples with different P/V molar ratios were prepared in mixture of isobutanol and benzyl alcohol, and their catalytic performance for selective oxidation of propane to acrylic...Vanadium phosphorus oxide (VPO) catalyst samples with different P/V molar ratios were prepared in mixture of isobutanol and benzyl alcohol, and their catalytic performance for selective oxidation of propane to acrylic acid (AA) and acetic acid (HAc) by lattice oxygen was investigated in a pulse reactor. The results showed that the AA and HAc only formed over the catalyst samples with n (P)/ n (V)>1 0. The proper n (P)/ n (V) is about 1 1, with which the catalyst samples have the best catalytic performance and maximum reversible oxygen storage capacity. It was also found that the ratio of n (AA)/ n (HAc) increased with the increasing of both the reaction temperature and the n (P)/ n (V) in the catalyst. The XRD results indicated that the title reaction is sensitive to the crystal structure and the active phase is (VO) 2P 2O 7.展开更多
The selective oxidation of propane over vanadium phosphorus oxide(VPO) catal yst has been investigated by using chromatography in a pulse reactor. The results showed that it is the lattice oxygen that oxidizes propane...The selective oxidation of propane over vanadium phosphorus oxide(VPO) catal yst has been investigated by using chromatography in a pulse reactor. The results showed that it is the lattice oxygen that oxidizes propane to form acrylic acid and acetic acid. This mechanism was also supported by TPD and XPS data. It is concluded that the oxidation of propane takes place on the surface of the catalyst according to Mars van Krevelen mechani sm , so that it could be implemented in a circulating fluidized bed(CFB) riser reactor. The re oxidation of VPO catslyst is found to be the rate controlling step in the oxidation reaction.展开更多
基金国家自然科学基金委中国石油化工集团公司联合资助重大基金项目 (No 2 9792 0 70 )~~
文摘The roles of adsorbed oxygen and lattice oxygen on the surface of VPO catalyst for n butane selective oxidation were experimentally studied by using on line mass spectroscopy (MS) transient response measurement in a fixed bed micro reactor. The results showed that the lattice oxygen led to selective oxidation,while adsorbed oxygen led to deep oxidation. Gaseous oxygen could be adsorbed on the surface of the VPO catalyst and transformed to lattice oxygen but did not directly participate in selective oxidation. The diffusion of lattice oxygen from the bulk phase to the surface might be the rate controlling step of unsteady state oxidation when n butane selective oxidation and VPO catalyst re oxidation were performed separately.Increasing the diffusion rate of the lattice oxygen and usable lattice oxygen capacity in VPO catalyst could remarkably improve the reaction performance in a fixed bed reactor.
文摘Vanadium phosphorus oxide (VPO) catalyst samples with different P/V molar ratios were prepared in mixture of isobutanol and benzyl alcohol, and their catalytic performance for selective oxidation of propane to acrylic acid (AA) and acetic acid (HAc) by lattice oxygen was investigated in a pulse reactor. The results showed that the AA and HAc only formed over the catalyst samples with n (P)/ n (V)>1 0. The proper n (P)/ n (V) is about 1 1, with which the catalyst samples have the best catalytic performance and maximum reversible oxygen storage capacity. It was also found that the ratio of n (AA)/ n (HAc) increased with the increasing of both the reaction temperature and the n (P)/ n (V) in the catalyst. The XRD results indicated that the title reaction is sensitive to the crystal structure and the active phase is (VO) 2P 2O 7.
文摘The selective oxidation of propane over vanadium phosphorus oxide(VPO) catal yst has been investigated by using chromatography in a pulse reactor. The results showed that it is the lattice oxygen that oxidizes propane to form acrylic acid and acetic acid. This mechanism was also supported by TPD and XPS data. It is concluded that the oxidation of propane takes place on the surface of the catalyst according to Mars van Krevelen mechani sm , so that it could be implemented in a circulating fluidized bed(CFB) riser reactor. The re oxidation of VPO catslyst is found to be the rate controlling step in the oxidation reaction.
