A SAPO-11 silicoaluminophosphate molecular sieve with stable crystal structure was synthesized for the first time. After removing template by calcination, its crystal space group still retains Icm2 which the as-synthe...A SAPO-11 silicoaluminophosphate molecular sieve with stable crystal structure was synthesized for the first time. After removing template by calcination, its crystal space group still retains Icm2 which the as-synthesized has. The catalyst deriving from the present SAPO-11 materials shows higher isomerization selectivity and higher paraffin hydroisomerization yield than those reported elsewhere.展开更多
To improve oil quality,ZSM-22/SAPO-11 composite molecular sieves were synthesized by adding ZSM-22 into a synthetic gel of SAPO-11 for n-decane hydroisomerization.The mass ratios of ZSM-22/(ZSM-22+SAPO-11)in the compo...To improve oil quality,ZSM-22/SAPO-11 composite molecular sieves were synthesized by adding ZSM-22 into a synthetic gel of SAPO-11 for n-decane hydroisomerization.The mass ratios of ZSM-22/(ZSM-22+SAPO-11)in the composite molecular sieves were optimized and the optimal ZSM-22/SAPO-11 composite(ZS-9)was obtained.The electrostatic repulsions between the ZSM-22 precursors and the SAPO-11 crystalline nuclei produced small ZSM-22 and SAPO-11 crystallites in ZS-9,which increased the specific surface area and mesopore volume and thereby exposed more acid sites.In comparison with conventional SAPO-11,ZSM-22 and their mechanical mixture,ZS-9 with smaller crystallites and the optimal medium and strong Brønsted acid centers(MSBAC)content displayed a higher yield of branched C_(10) isomers(81.6%),lower cracking selectivity(11.9%)and excellent stability.The correlation between the i-C_(10) selectivity and the MSBAC density of molecular sieves indicated that the selectivity for branched C_(10) isomers first increased and then decreased with increasing MSBAC density on the molecular sieves,and the maximum selectivity(87.7%)occurred with a density of 9.6×10^(−2)μmol m^(−2).展开更多
To enhance the gasoline octane number,low-octane linear n-alkanes should be converted into their high-octane di-branched isomers via n-alkane hydroisomerization.Therefore,hierarchical SAPO-11-based catalysts are prepa...To enhance the gasoline octane number,low-octane linear n-alkanes should be converted into their high-octane di-branched isomers via n-alkane hydroisomerization.Therefore,hierarchical SAPO-11-based catalysts are prepared by adding different contents of sodium dodecylbenzene sulfonate(SDBS),and they are applied in n-nonane hydroisomerization.When n(SDBS)/n(SiO2)is less than or equal to 0.125,the synthesized hierarchical molecular sieves are all pure SAPO-11,and as the SDBS content increases,the submicron particle size decreases,and the external surface area(ESA)increases.Additionally,these hierarchical SAPO-11 have smaller submicron particles and higher ESA values than conventional SAPO-11.When n(SDBS)/n(SiO2)is greater than 0.125,with increasing SDBS content(n(SDBS)/n(SiO2)=0.25),the synthesized SAPO-11 contains amorphous materials,which leads to a decline in the ESA;with the further increase in SDBS content(n(SDBS)/n(SiO2)=0.5),the products are all amorphous materials.These results indicate that in the case of n(SDBS)/n(SiO2)=0.125,the synthesized SAPO-11 molecular sieve(S–S3)has the most external Brønsted acid centers and the highest ESA of these SAPO-11,and these advantages favor generation of the di-branched isomers in hydrocarbon hydroisomerization.Among these Pt/SAPO-11 catalysts,Pt/S–S3 displays the highest selectivity to entire isomers(83.4%),the highest selectivity to di-branched isomers(28.1%)and the minimum hydrocracking selectivity(15.7%)in n-nonane hydroisomerization.展开更多
For enhancing the activity of Ni/TiO2-SAPO-11 catalyst, SAPO-11, the precursor was prepared by hydrothermal crystallization, and TiO2-SAPO-11 complex carrier was prepared by sol-gel method, then Ni/TiO2-SAPO-11 was pr...For enhancing the activity of Ni/TiO2-SAPO-11 catalyst, SAPO-11, the precursor was prepared by hydrothermal crystallization, and TiO2-SAPO-11 complex carrier was prepared by sol-gel method, then Ni/TiO2-SAPO-11 was produced by the final product. The catalytic performance of Ni/TiO2-SAPO-11 was studied in n-heptane isomerization, and the impact of catalyst preparation conditions on n-heptane isomerization was discussed in detail. The results showed that, with 20% of TiO2 composition, 2% of Ni capacity percentage and calcined temperature at 500°C, conversion of n-heptane and isomerization selectivity was up to 40.94% and 88.97% respectively.展开更多
The effects of the synthetic condition of SAPO-11 molecular sieves on ethanol dehydration to ethylene were studied.Product-compositions,ethanol conversion,and selectivity to ethylene of synthesized and commercial SAPO...The effects of the synthetic condition of SAPO-11 molecular sieves on ethanol dehydration to ethylene were studied.Product-compositions,ethanol conversion,and selectivity to ethylene of synthesized and commercial SAPO-11 molecular sieves were compared.Results are as follows:the optimal synthetic conditions for SAPO-11 molecular sieves are adding pseudoboehmite before orthophoshporic,using di-npropylamine as the template,having a mass fraction of 40%colloidal silica as the silica source and the starting gel obtained,and running at 200℃ for 48 h.From the patterns of NH3-TPD,the amount of acid synthesized by SAPO-11 molecular sieves is less than that by commercial SAPO-11 molecular sieves,and has a stronger weak acid.Also,ethanol conversion and selectivity to ethylene reached 99%at 280℃ on synthesized SAPO-11,lower by 20℃ compared to commercial SAPO-11.For two SAPO-11 molecular sieves,the by-products in the gas phase are mainly ethane,propane,propene,isobutane,n-butane,propadiene,butylene and some higher hydrocarbons.The by-products in the liquid phase are ethyl ether and acetaldehyde.展开更多
文摘A SAPO-11 silicoaluminophosphate molecular sieve with stable crystal structure was synthesized for the first time. After removing template by calcination, its crystal space group still retains Icm2 which the as-synthesized has. The catalyst deriving from the present SAPO-11 materials shows higher isomerization selectivity and higher paraffin hydroisomerization yield than those reported elsewhere.
基金The authors gratefully acknowledge the financial support of Science Foundation of China University of Petroleum,Beijing(Grant No.KYJJ2012-03-03).
文摘To improve oil quality,ZSM-22/SAPO-11 composite molecular sieves were synthesized by adding ZSM-22 into a synthetic gel of SAPO-11 for n-decane hydroisomerization.The mass ratios of ZSM-22/(ZSM-22+SAPO-11)in the composite molecular sieves were optimized and the optimal ZSM-22/SAPO-11 composite(ZS-9)was obtained.The electrostatic repulsions between the ZSM-22 precursors and the SAPO-11 crystalline nuclei produced small ZSM-22 and SAPO-11 crystallites in ZS-9,which increased the specific surface area and mesopore volume and thereby exposed more acid sites.In comparison with conventional SAPO-11,ZSM-22 and their mechanical mixture,ZS-9 with smaller crystallites and the optimal medium and strong Brønsted acid centers(MSBAC)content displayed a higher yield of branched C_(10) isomers(81.6%),lower cracking selectivity(11.9%)and excellent stability.The correlation between the i-C_(10) selectivity and the MSBAC density of molecular sieves indicated that the selectivity for branched C_(10) isomers first increased and then decreased with increasing MSBAC density on the molecular sieves,and the maximum selectivity(87.7%)occurred with a density of 9.6×10^(−2)μmol m^(−2).
基金The authors gratefully acknowledge the financial support of the National Natural Science Foundation of China(Grant No.21978323)。
文摘To enhance the gasoline octane number,low-octane linear n-alkanes should be converted into their high-octane di-branched isomers via n-alkane hydroisomerization.Therefore,hierarchical SAPO-11-based catalysts are prepared by adding different contents of sodium dodecylbenzene sulfonate(SDBS),and they are applied in n-nonane hydroisomerization.When n(SDBS)/n(SiO2)is less than or equal to 0.125,the synthesized hierarchical molecular sieves are all pure SAPO-11,and as the SDBS content increases,the submicron particle size decreases,and the external surface area(ESA)increases.Additionally,these hierarchical SAPO-11 have smaller submicron particles and higher ESA values than conventional SAPO-11.When n(SDBS)/n(SiO2)is greater than 0.125,with increasing SDBS content(n(SDBS)/n(SiO2)=0.25),the synthesized SAPO-11 contains amorphous materials,which leads to a decline in the ESA;with the further increase in SDBS content(n(SDBS)/n(SiO2)=0.5),the products are all amorphous materials.These results indicate that in the case of n(SDBS)/n(SiO2)=0.125,the synthesized SAPO-11 molecular sieve(S–S3)has the most external Brønsted acid centers and the highest ESA of these SAPO-11,and these advantages favor generation of the di-branched isomers in hydrocarbon hydroisomerization.Among these Pt/SAPO-11 catalysts,Pt/S–S3 displays the highest selectivity to entire isomers(83.4%),the highest selectivity to di-branched isomers(28.1%)and the minimum hydrocracking selectivity(15.7%)in n-nonane hydroisomerization.
文摘For enhancing the activity of Ni/TiO2-SAPO-11 catalyst, SAPO-11, the precursor was prepared by hydrothermal crystallization, and TiO2-SAPO-11 complex carrier was prepared by sol-gel method, then Ni/TiO2-SAPO-11 was produced by the final product. The catalytic performance of Ni/TiO2-SAPO-11 was studied in n-heptane isomerization, and the impact of catalyst preparation conditions on n-heptane isomerization was discussed in detail. The results showed that, with 20% of TiO2 composition, 2% of Ni capacity percentage and calcined temperature at 500°C, conversion of n-heptane and isomerization selectivity was up to 40.94% and 88.97% respectively.
基金This work was financially supported by the National High Technology Research and Development Program of China(No.2006AA020101).
文摘The effects of the synthetic condition of SAPO-11 molecular sieves on ethanol dehydration to ethylene were studied.Product-compositions,ethanol conversion,and selectivity to ethylene of synthesized and commercial SAPO-11 molecular sieves were compared.Results are as follows:the optimal synthetic conditions for SAPO-11 molecular sieves are adding pseudoboehmite before orthophoshporic,using di-npropylamine as the template,having a mass fraction of 40%colloidal silica as the silica source and the starting gel obtained,and running at 200℃ for 48 h.From the patterns of NH3-TPD,the amount of acid synthesized by SAPO-11 molecular sieves is less than that by commercial SAPO-11 molecular sieves,and has a stronger weak acid.Also,ethanol conversion and selectivity to ethylene reached 99%at 280℃ on synthesized SAPO-11,lower by 20℃ compared to commercial SAPO-11.For two SAPO-11 molecular sieves,the by-products in the gas phase are mainly ethane,propane,propene,isobutane,n-butane,propadiene,butylene and some higher hydrocarbons.The by-products in the liquid phase are ethyl ether and acetaldehyde.
