Molecular sieves of SAPO-41 with different silicon contents were synthesized and characterized by XRD,N2 adsorption,XRF,pyridine-IR and 29SiMAS-NMR.The isomerization properties of the SAPO-41 were investigated by usin...Molecular sieves of SAPO-41 with different silicon contents were synthesized and characterized by XRD,N2 adsorption,XRF,pyridine-IR and 29SiMAS-NMR.The isomerization properties of the SAPO-41 were investigated by using m-xylene as a feedstock.The SAPO-41 obtained from the synthesis gel with SiO2/Al2O3=0.3 showed the highest activity to the isomerization of m-xylene and the largest number of Brnsted acid sites was also observed with Py-IR over this sample.The state of Si in the framework of SAPO-41 plays a predominant role on the Brnsted acidity.The relationship between the activity and the acidity obtained in this study can be explained in terms of the distribution of stronger Brnsted acid sites.展开更多
分别以二正丁胺(DBA)、拟薄水铝石、磷酸和硅溶胶为模板剂、铝源、磷源和硅源,通过水热合成法,制备出纯相的SAPO-41分子筛。采用XRD、氮气物理吸附、29Si MAS NMR、SEM和吡啶红外(Py-IR)等分析表征手段,考察了DBA用量和晶化时间对SAPO-4...分别以二正丁胺(DBA)、拟薄水铝石、磷酸和硅溶胶为模板剂、铝源、磷源和硅源,通过水热合成法,制备出纯相的SAPO-41分子筛。采用XRD、氮气物理吸附、29Si MAS NMR、SEM和吡啶红外(Py-IR)等分析表征手段,考察了DBA用量和晶化时间对SAPO-41分子筛的晶体结构、孔结构、分子筛骨架中Si原子分布、形貌以及B酸中心强度的影响。降低DBA用量会减弱AFO拓扑结构的导向能力,延长晶化时间不仅有利于AFO拓扑结构的生成,而且有利于分子筛结晶度提高。展开更多
The hydroisomerization of n-hexadecane over Pt-Pd bimetallic catalysts is an effective way to produce clean fuel oil.This work reports a useful preparation method of bimetallic bifunctional catalysts by a co-impregnat...The hydroisomerization of n-hexadecane over Pt-Pd bimetallic catalysts is an effective way to produce clean fuel oil.This work reports a useful preparation method of bimetallic bifunctional catalysts by a co-impregnation or sequential impregnation process.Furthermore,monometallic catalysts with loading either Pt or Pd are also prepared for comparison.The effects of the metal species and impregnation order on the characteristics and catalytic performance of the catalysts are investigated.The catalytic test results indicate that the maximum iso-hexadecane yield over different catalysts increases as follows:Pt/silicoaluminophosphate SAPO-41<Pd/SAPO-41<Pt^(*)-Pd/SAPO-41(prepared by sequential impregnation)<Pt-Pd/SAPO-41(prepared by co-impregnation).Owing to the synergic effects between Pt and Pd,the Pt-Pd/SAPO-41 catalyst prepared by the co-impregnation method demonstrates the effective promotion of(de)hydrogenation activity.Therefore,this catalyst exhibits the highest iso-hexadecane yield of 89.4%when the n-hexadecane conversion is 96.3%.Additionally,the Pt-Pd/SAPO-41 catalyst also presents the highest catalytic activity and best stability even after 150 h long-term tests.展开更多
文摘Molecular sieves of SAPO-41 with different silicon contents were synthesized and characterized by XRD,N2 adsorption,XRF,pyridine-IR and 29SiMAS-NMR.The isomerization properties of the SAPO-41 were investigated by using m-xylene as a feedstock.The SAPO-41 obtained from the synthesis gel with SiO2/Al2O3=0.3 showed the highest activity to the isomerization of m-xylene and the largest number of Brnsted acid sites was also observed with Py-IR over this sample.The state of Si in the framework of SAPO-41 plays a predominant role on the Brnsted acidity.The relationship between the activity and the acidity obtained in this study can be explained in terms of the distribution of stronger Brnsted acid sites.
文摘分别以二正丁胺(DBA)、拟薄水铝石、磷酸和硅溶胶为模板剂、铝源、磷源和硅源,通过水热合成法,制备出纯相的SAPO-41分子筛。采用XRD、氮气物理吸附、29Si MAS NMR、SEM和吡啶红外(Py-IR)等分析表征手段,考察了DBA用量和晶化时间对SAPO-41分子筛的晶体结构、孔结构、分子筛骨架中Si原子分布、形貌以及B酸中心强度的影响。降低DBA用量会减弱AFO拓扑结构的导向能力,延长晶化时间不仅有利于AFO拓扑结构的生成,而且有利于分子筛结晶度提高。
基金the financial supports from the National Key R&D Program of China,Intergovernmental International Science and Technology Innovation Cooperation Key Project(Grant No.2018YFE0108800)the National Natural Science Foundation of China(Grant Nos.21676074 and 21706053)National Key Research and Development Project,National Ministry of Education“Silk Road 1+1”Research Cooperation Project.
文摘The hydroisomerization of n-hexadecane over Pt-Pd bimetallic catalysts is an effective way to produce clean fuel oil.This work reports a useful preparation method of bimetallic bifunctional catalysts by a co-impregnation or sequential impregnation process.Furthermore,monometallic catalysts with loading either Pt or Pd are also prepared for comparison.The effects of the metal species and impregnation order on the characteristics and catalytic performance of the catalysts are investigated.The catalytic test results indicate that the maximum iso-hexadecane yield over different catalysts increases as follows:Pt/silicoaluminophosphate SAPO-41<Pd/SAPO-41<Pt^(*)-Pd/SAPO-41(prepared by sequential impregnation)<Pt-Pd/SAPO-41(prepared by co-impregnation).Owing to the synergic effects between Pt and Pd,the Pt-Pd/SAPO-41 catalyst prepared by the co-impregnation method demonstrates the effective promotion of(de)hydrogenation activity.Therefore,this catalyst exhibits the highest iso-hexadecane yield of 89.4%when the n-hexadecane conversion is 96.3%.Additionally,the Pt-Pd/SAPO-41 catalyst also presents the highest catalytic activity and best stability even after 150 h long-term tests.
