In this study,selective dealumination of Beta zeolites was performed through partially removing the templating agent in Beta zeolites by calcination and then removing the aluminum on the external surface of Beta zeoli...In this study,selective dealumination of Beta zeolites was performed through partially removing the templating agent in Beta zeolites by calcination and then removing the aluminum on the external surface of Beta zeolites with acid treatment.Hydrocracking catalysts were prepared by loading WO_(3)onto these dealuminated Beta zeolites.It was shown that the surface SiO_(2)/Al_(2)O_(3)of selectively dealuminated Beta zeolites was higher than that of conventionally dealuminated samples for the same bulk SiO_(2)/Al_(2)O_(3),and the hydrogenation activity of the catalyst of the selectively dealuminated Beta zeolites was lower than that of conventionally dealuminated Beta zeolites.The experimental results for tetralin hydrocracking to BTX showed that the catalysts based on the selectively dealuminated Beta zeolites had higher BTX selectivity and lower coke formation rate than that the catalysts based on the conventionally dealuminated Beta zeolites.展开更多
Ethylene oligomerization using ZSM-5 zeolite was investigated to study the role of Bronsted acid sites in the formation of higher hydrocarbons. The oligomerization of olefins, dependent on the acidity of ZSM-5 zeolite...Ethylene oligomerization using ZSM-5 zeolite was investigated to study the role of Bronsted acid sites in the formation of higher hydrocarbons. The oligomerization of olefins, dependent on the acidity of ZSM-5 zeolite, is an important step in the conversion of natural gas to liquid fuels. The framework Si/Al ratio reflects the number of potential acid sites and the acid strength of the ZSM-5 catalyst. ZSM-5 with the mole ratio SiO2/Al2O3 equal to 30 was dealuminated for different periods of time according to the acidic ion-exchange method to produce ZSM-5 with various Si/Al ratios. The FT-IR analysis revealed that the integrated framework aluminum band, non-framework aluminum band, and silanol groups areas of the ZSM-5 zeolites decreased after being dealuminated. The performance of the dealuminated zeolite was tested for ethylene oligomerization. The results demonstrated that the dealumination of ZSM-5 led to higher ethylene conversion, but the gasoline selectivity was reduced compared to the performance of a ZSM-5 zeolite. The characterization results revealed the amount of aluminum in the zeolitic framework, the crystallinity of the ZSM-5 zeolite, and the Si/Al ratio affected the formation of Bronsted acid sites. The number of the Bronsted acid sites on the catalyst active sites is important in the olefin conversion to liquid hydrocarbons.展开更多
This article mainly worked on methods to reduce side reactions of the de-ethylating type catalyst for xylene isomerization. In laboratory the de-ethylating type catalyst for xylene isomerization was subjected to steam...This article mainly worked on methods to reduce side reactions of the de-ethylating type catalyst for xylene isomerization. In laboratory the de-ethylating type catalyst for xylene isomerization was subjected to steam treatment at different temperatures and durations to achieve dealumination of the ZSM-5 zeolite to some extent, which could affect the change in BrФnsted acid content to decrease xylene loss along with reduction of side reactions. Test results showed that the degree for reducing side reactions by steam treatment depended upon two important parameters-treating temperature and duration. The optimal condition required treating the catalyst at 500℃ for 8 hours.展开更多
A hetero-crystalline seeding method to prepare a unique MFI type zeolite with mesopores of ca. 4 nm diameter designated as the ZRP zeolite, which possesses high stability and selectivity and is used as component of FC...A hetero-crystalline seeding method to prepare a unique MFI type zeolite with mesopores of ca. 4 nm diameter designated as the ZRP zeolite, which possesses high stability and selectivity and is used as component of FCC catalysts to produce high-octane gasoline and light olefins, was developed. With the DOCR and DOCP catalysts containing the ZRP zeolite modified by phosphorus-incorporation as the octaneenhancing catalysts, the commercial trial was carried out in a 0.8Mt/a RFCC unit with a feedstock composed of Daqing atmospheric residue. As compared to the base catalyst, the LPG+gasoline+LCO product yield obtained from this catalyst was increased by 0.53m%. Meanwhile, the RON and MON of gasoline was increased by 1.4 and 2.4 units, respectively. The higher increment of MON is attributable to the higher isoparaffines content in gasoline. This result indicates that the ZRP zeolite possesses higher isomerization selectivity.展开更多
NaY zeolite was modified through dealumination with oxalic acid,and the HY zeolite was obtained by calcination of the modified NaY zeolite.The zeolite molding process was carried out at ambient temperature(25℃),and t...NaY zeolite was modified through dealumination with oxalic acid,and the HY zeolite was obtained by calcination of the modified NaY zeolite.The zeolite molding process was carried out at ambient temperature(25℃),and the influence of solid/fuel mass ratio and adsorptive desulfurization time on the HY zeolite were investigated through tests on static selective adsorptive desulfurization of FCC gasoline containing organic sulfur compounds(with a S content=135 ppm).The sulfur content and sulphide types in the FCC gasoline were analyzed by a GC 2010 sulfur analyzer and a GC-SCD chromatograph.The test results showed that the molded HY zeolite was better than the unmolded HY zeolite.At a static adsorptive desulfurization time on the molded HY zeolite equating to 6 hours,a solid/fuel mass ratio of 1:3,the sulfur content of FCC gasoline was decreased to 30 ppm,and the desulfurization rate was equal to 78%.When the breakthrough point of the molded HY was equal to 50 ppm,the molded HY zeolite was capable of adsorbing 4.86 mg of sulfur per gram of adsorbent.And the regeneration rate of molded HY zeolite was equal to 98%.展开更多
Effects of hydrochloride acid dealumination of mordenite(MOR) catalysts for the synthesis of 1-phenyl-1-xylyl ethane(PXE) were investigated. The structure and acidity of catalysts were characterized by XRD, BET, XRF, ...Effects of hydrochloride acid dealumination of mordenite(MOR) catalysts for the synthesis of 1-phenyl-1-xylyl ethane(PXE) were investigated. The structure and acidity of catalysts were characterized by XRD, BET, XRF, FT-IR, 27Al NMR and NH3-TPD techniques. The catalytic performance of the acid-treated MOR zeolites was studied through using the alkylation of o-xylene with styrene. The test results showed that the strength of remaining Br?nsted acid sites increased despite the reduction of total number of acid sites after dealumination, and the micropores of HMOR were slightly enlarged coupled with the formation of secondary mesopores. Additionally, the modified HMOR zeolites showed longer catalyst life with the styrene conversion rate retained. Among the catalysts employed in this study, the modified mordenite that was dealuminated by HCl(2 mol/L) could be used repeatedly without significant loss of activity and selectivity during six catalytic runs, which have been ascribed to its specific acidity and structural properties.展开更多
文摘In this study,selective dealumination of Beta zeolites was performed through partially removing the templating agent in Beta zeolites by calcination and then removing the aluminum on the external surface of Beta zeolites with acid treatment.Hydrocracking catalysts were prepared by loading WO_(3)onto these dealuminated Beta zeolites.It was shown that the surface SiO_(2)/Al_(2)O_(3)of selectively dealuminated Beta zeolites was higher than that of conventionally dealuminated samples for the same bulk SiO_(2)/Al_(2)O_(3),and the hydrogenation activity of the catalyst of the selectively dealuminated Beta zeolites was lower than that of conventionally dealuminated Beta zeolites.The experimental results for tetralin hydrocracking to BTX showed that the catalysts based on the selectively dealuminated Beta zeolites had higher BTX selectivity and lower coke formation rate than that the catalysts based on the conventionally dealuminated Beta zeolites.
文摘Ethylene oligomerization using ZSM-5 zeolite was investigated to study the role of Bronsted acid sites in the formation of higher hydrocarbons. The oligomerization of olefins, dependent on the acidity of ZSM-5 zeolite, is an important step in the conversion of natural gas to liquid fuels. The framework Si/Al ratio reflects the number of potential acid sites and the acid strength of the ZSM-5 catalyst. ZSM-5 with the mole ratio SiO2/Al2O3 equal to 30 was dealuminated for different periods of time according to the acidic ion-exchange method to produce ZSM-5 with various Si/Al ratios. The FT-IR analysis revealed that the integrated framework aluminum band, non-framework aluminum band, and silanol groups areas of the ZSM-5 zeolites decreased after being dealuminated. The performance of the dealuminated zeolite was tested for ethylene oligomerization. The results demonstrated that the dealumination of ZSM-5 led to higher ethylene conversion, but the gasoline selectivity was reduced compared to the performance of a ZSM-5 zeolite. The characterization results revealed the amount of aluminum in the zeolitic framework, the crystallinity of the ZSM-5 zeolite, and the Si/Al ratio affected the formation of Bronsted acid sites. The number of the Bronsted acid sites on the catalyst active sites is important in the olefin conversion to liquid hydrocarbons.
文摘This article mainly worked on methods to reduce side reactions of the de-ethylating type catalyst for xylene isomerization. In laboratory the de-ethylating type catalyst for xylene isomerization was subjected to steam treatment at different temperatures and durations to achieve dealumination of the ZSM-5 zeolite to some extent, which could affect the change in BrФnsted acid content to decrease xylene loss along with reduction of side reactions. Test results showed that the degree for reducing side reactions by steam treatment depended upon two important parameters-treating temperature and duration. The optimal condition required treating the catalyst at 500℃ for 8 hours.
文摘A hetero-crystalline seeding method to prepare a unique MFI type zeolite with mesopores of ca. 4 nm diameter designated as the ZRP zeolite, which possesses high stability and selectivity and is used as component of FCC catalysts to produce high-octane gasoline and light olefins, was developed. With the DOCR and DOCP catalysts containing the ZRP zeolite modified by phosphorus-incorporation as the octaneenhancing catalysts, the commercial trial was carried out in a 0.8Mt/a RFCC unit with a feedstock composed of Daqing atmospheric residue. As compared to the base catalyst, the LPG+gasoline+LCO product yield obtained from this catalyst was increased by 0.53m%. Meanwhile, the RON and MON of gasoline was increased by 1.4 and 2.4 units, respectively. The higher increment of MON is attributable to the higher isoparaffines content in gasoline. This result indicates that the ZRP zeolite possesses higher isomerization selectivity.
文摘NaY zeolite was modified through dealumination with oxalic acid,and the HY zeolite was obtained by calcination of the modified NaY zeolite.The zeolite molding process was carried out at ambient temperature(25℃),and the influence of solid/fuel mass ratio and adsorptive desulfurization time on the HY zeolite were investigated through tests on static selective adsorptive desulfurization of FCC gasoline containing organic sulfur compounds(with a S content=135 ppm).The sulfur content and sulphide types in the FCC gasoline were analyzed by a GC 2010 sulfur analyzer and a GC-SCD chromatograph.The test results showed that the molded HY zeolite was better than the unmolded HY zeolite.At a static adsorptive desulfurization time on the molded HY zeolite equating to 6 hours,a solid/fuel mass ratio of 1:3,the sulfur content of FCC gasoline was decreased to 30 ppm,and the desulfurization rate was equal to 78%.When the breakthrough point of the molded HY was equal to 50 ppm,the molded HY zeolite was capable of adsorbing 4.86 mg of sulfur per gram of adsorbent.And the regeneration rate of molded HY zeolite was equal to 98%.
基金the financial supports of the National Natural Science Foundation of China (Grant No. 21306023, 21376051, 21106017 and 51077013)the Fund Project for Transformation of Scientific and Technological Achievements of Jiangsu Province (Grant No. BA2011086)+2 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20100092120047)the Key Program for the Scientific Research Guiding Fund of Basic Scientific Research Operation Expenditure of Southeast University (Grant No. 3207043101)the Instrumental Analysis Fund of Southeast University
文摘Effects of hydrochloride acid dealumination of mordenite(MOR) catalysts for the synthesis of 1-phenyl-1-xylyl ethane(PXE) were investigated. The structure and acidity of catalysts were characterized by XRD, BET, XRF, FT-IR, 27Al NMR and NH3-TPD techniques. The catalytic performance of the acid-treated MOR zeolites was studied through using the alkylation of o-xylene with styrene. The test results showed that the strength of remaining Br?nsted acid sites increased despite the reduction of total number of acid sites after dealumination, and the micropores of HMOR were slightly enlarged coupled with the formation of secondary mesopores. Additionally, the modified HMOR zeolites showed longer catalyst life with the styrene conversion rate retained. Among the catalysts employed in this study, the modified mordenite that was dealuminated by HCl(2 mol/L) could be used repeatedly without significant loss of activity and selectivity during six catalytic runs, which have been ascribed to its specific acidity and structural properties.
