The acidic modulations of a series of HZSM-5 catalysts were successfully made by calcination at different treatment temperatures, i.e. 500, 600, 650, 700 and 800 ℃, respectively. The results indicated that the total ...The acidic modulations of a series of HZSM-5 catalysts were successfully made by calcination at different treatment temperatures, i.e. 500, 600, 650, 700 and 800 ℃, respectively. The results indicated that the total acid amounts, their density and the amount of B-type acid of HZSM-5 catalysts rapidly decreased, while the amounts of L-type acid had almost no change and thus the ratio of L/B was obviously enhanced with the increase of calcination temperature （excluding 800 ℃）. The catalytic performances of modified HZSM-5 catalysts for the cracking of n-butane were also investigated. The main properties of these catalysts were characterized by means of XRD, N2 adsorption at low temperature, NH3-TPD, FTIR of pyridine adsorption and BET surface area measurements. The results showed that HZSM-5 zeolite pretreated at 800 ℃ had very low catalytic activity for n-butane cracking. In the calcination temperature range of 500-700 ℃, the total selectivity to olefins, propylene and butene were increased with the increase of calcination temperature, while, the selectivity for arene decreased with the calcination temperature. The HZSM-5 zeolite calcined at 700 ℃ produced light olefins with high yield, at the reaction temperature of 650 ℃ the yields of total olefins and ethylene were 52.8% and 29.4%, respectively. Besides, the more important role is that high calcination temperature treatment improved the duration stability of HZSM-5 zeolites. The effect of calcination temperature on the physico-chemical properties and catalytic performance of HZSM-5 for cracking of n-butane was explored. It was found that the calcination temperature had large effects on the surface area, crystallinity and acid properties of HZSM-5 catalyst, which further affected the catalytic performance for n-butane cracking.展开更多
A series of phosphorus-modified PITQ-13 catalysts was prepared by wet impregnation of NH4H2PO4 solution into an HITQ-13 parent. The catalysts were characterized using XRD, N2 adsorption, MAS NMR and NH3-TPD. Their cat...A series of phosphorus-modified PITQ-13 catalysts was prepared by wet impregnation of NH4H2PO4 solution into an HITQ-13 parent. The catalysts were characterized using XRD, N2 adsorption, MAS NMR and NH3-TPD. Their catalytic performance in 1-butene catalytic cracking was evaluated in a fixed fluidized bed reactor. The results showed that the crystallinity, surface area and pore volume of P-modified PITQ-13 catalysts decreased with the increasing amounts of P. The number of weak acid sites increased, whereas that of strong acidity decreased. The selectivity to propylene in 1-butene cracking reactions increased because of the decrease in strong acidity. The yield of propylene achieved 41.6% over PITQ-13-2 catalyst with a P content of 1.0 wt%, which was 5.1% greater than that achieved over HITQ-13 catalyst.展开更多
In order to reducing olefin fraction in FCC gasoline, USY zeolite, the active component of FCC catalyst, was modified by impregnating or ion-exchanging chromium. Acidity and cracking activity of modified USY zeolite w...In order to reducing olefin fraction in FCC gasoline, USY zeolite, the active component of FCC catalyst, was modified by impregnating or ion-exchanging chromium. Acidity and cracking activity of modified USY zeolite were studied by IR and MAT. It was found that both amount and strength of Bronsted acid site on the surface of modified USY zeolite were increased obviously, but the Lewis acid site was almost unchanged. The hydrogen-transfer activity of modified USY zeolite was independent of the ways of loading chromium, but the isomerization activity of USY zoilite was dependent of the loading methods. The impregnated Cr-USY was better than ion-exchanged Cr-USY. The activities for cracking, hydrogen-transfer and isomerization reaction of modified USY zeolite were increased first, and then decreased with increasing of chromium amount. The cracking catalyst, USY zeolite with 0.01% chromium as the active component, showed higher activities for cracking, hydrogen-transfer and isomerization reaction. The olefin content in cracking gasoline was decreased evidently, and the isomeric alkane, cycloalkane and aromatic hydrocarbon were increased. The extent of olefin decline was high to 28 %, but the contents of isomeric alkane, cycloalkane and aromatic hydrocarbon were enhanced in evidence, they were 6.8 %, 20 % and 27.6 % separately comparing to the USY zeolite cracking catalyst. The decreasing of olefin and increasing of cycloalkane and aromatic hydrocarbon improved the octane number of cracking gasoline. It was indicate that the chromium modified USY zeolite was favorable to the olefin-reduce cracking catalysts.展开更多
基金The authors would like to thank the financial support from the National Basic Research Program of China fgrant No．2004CB 217806)the National Natural Science Foundation of China (Grant No．20373043) the Scientific Research Key Foundation for the Returned Overseas Chinese Scholars of State Education Ministry．
文摘The acidic modulations of a series of HZSM-5 catalysts were successfully made by calcination at different treatment temperatures, i.e. 500, 600, 650, 700 and 800 ℃, respectively. The results indicated that the total acid amounts, their density and the amount of B-type acid of HZSM-5 catalysts rapidly decreased, while the amounts of L-type acid had almost no change and thus the ratio of L/B was obviously enhanced with the increase of calcination temperature （excluding 800 ℃）. The catalytic performances of modified HZSM-5 catalysts for the cracking of n-butane were also investigated. The main properties of these catalysts were characterized by means of XRD, N2 adsorption at low temperature, NH3-TPD, FTIR of pyridine adsorption and BET surface area measurements. The results showed that HZSM-5 zeolite pretreated at 800 ℃ had very low catalytic activity for n-butane cracking. In the calcination temperature range of 500-700 ℃, the total selectivity to olefins, propylene and butene were increased with the increase of calcination temperature, while, the selectivity for arene decreased with the calcination temperature. The HZSM-5 zeolite calcined at 700 ℃ produced light olefins with high yield, at the reaction temperature of 650 ℃ the yields of total olefins and ethylene were 52.8% and 29.4%, respectively. Besides, the more important role is that high calcination temperature treatment improved the duration stability of HZSM-5 zeolites. The effect of calcination temperature on the physico-chemical properties and catalytic performance of HZSM-5 for cracking of n-butane was explored. It was found that the calcination temperature had large effects on the surface area, crystallinity and acid properties of HZSM-5 catalyst, which further affected the catalytic performance for n-butane cracking.
基金supported by PetroChina Company Limited(12-09-01-01)the National Basic Research Program of China(973 Program,2012CB215001)
文摘A series of phosphorus-modified PITQ-13 catalysts was prepared by wet impregnation of NH4H2PO4 solution into an HITQ-13 parent. The catalysts were characterized using XRD, N2 adsorption, MAS NMR and NH3-TPD. Their catalytic performance in 1-butene catalytic cracking was evaluated in a fixed fluidized bed reactor. The results showed that the crystallinity, surface area and pore volume of P-modified PITQ-13 catalysts decreased with the increasing amounts of P. The number of weak acid sites increased, whereas that of strong acidity decreased. The selectivity to propylene in 1-butene cracking reactions increased because of the decrease in strong acidity. The yield of propylene achieved 41.6% over PITQ-13-2 catalyst with a P content of 1.0 wt%, which was 5.1% greater than that achieved over HITQ-13 catalyst.
文摘In order to reducing olefin fraction in FCC gasoline, USY zeolite, the active component of FCC catalyst, was modified by impregnating or ion-exchanging chromium. Acidity and cracking activity of modified USY zeolite were studied by IR and MAT. It was found that both amount and strength of Bronsted acid site on the surface of modified USY zeolite were increased obviously, but the Lewis acid site was almost unchanged. The hydrogen-transfer activity of modified USY zeolite was independent of the ways of loading chromium, but the isomerization activity of USY zoilite was dependent of the loading methods. The impregnated Cr-USY was better than ion-exchanged Cr-USY. The activities for cracking, hydrogen-transfer and isomerization reaction of modified USY zeolite were increased first, and then decreased with increasing of chromium amount. The cracking catalyst, USY zeolite with 0.01% chromium as the active component, showed higher activities for cracking, hydrogen-transfer and isomerization reaction. The olefin content in cracking gasoline was decreased evidently, and the isomeric alkane, cycloalkane and aromatic hydrocarbon were increased. The extent of olefin decline was high to 28 %, but the contents of isomeric alkane, cycloalkane and aromatic hydrocarbon were enhanced in evidence, they were 6.8 %, 20 % and 27.6 % separately comparing to the USY zeolite cracking catalyst. The decreasing of olefin and increasing of cycloalkane and aromatic hydrocarbon improved the octane number of cracking gasoline. It was indicate that the chromium modified USY zeolite was favorable to the olefin-reduce cracking catalysts.
