| The alkanes isomerization reaction is the best method of preparation of high quality petroleum products,including n-heptane isomerization which has a good effect on improving the gasoline octane number.Therefore,the study of highly active and selective n-heptane isomerization catalyst became popular in the field of petrochemical project.The SAPO-11 molecular sieve has been applied in catalytic hydrogenation,catalytic cracking,isomeric dewaxing and alkylation of branched chain aromatic hydrocarbons,but the application of n-heptane in SAPO-11 molecular sieve is still researched.In view of this,Ni/SAPO-11,Ni-Sn/SAPO-11 and Ni-Co/SAPO-11 were synthesized by step impregnation method to load metal Ni and additives of Sn and Co to SAPO-11.It investigated the effect of preparation conditions,reduction of catalysts and reaction conditions on the properties of n-heptane isomerization reaction.The experimental results showed that the best Ni/SAPO-11 catalyst preparation and reaction conditions were:Ni load 5%?mass fraction?,the roasting temperature 400 oC,H2 flow rate 30 mL/min,reduction temperature 430oC,reduction time 4 h,reaction temperature 330 oC,WHSV 7.0 h-1,H2/C7 12.At this point,n-heptane conversion could reach 42.00%,the selectivity reached 49.00%.The best Ni-Sn/SAPO-11 catalyst preparation and reaction conditions were:Ni load 5%?mass fraction?,Sn load 4%,the roasting temperature 550 oC,H2 flow rate 30 m L/min,reduction temperature430 oC,reduction time 5 h,reaction temperature 300 oC,WHSV 6.8 h–1,H2/C7 14.Under the conditions,n-heptane conversion could reach 43.00%,and the selectivity reached 71.00%.The best Ni-Co/SAPO-11 catalyst preparation and reaction conditions were:Ni load 4%?mass fraction?,Co load 4%,the roasting temperature 550 oC,H2 flow rate 30 m L/min,reduction temperature 420 oC,reduction time 5 h,reaction temperature 280 oC,WHSV 6.5 h–1,H2/C7 13.And n-heptane conversion could reach 58.90%,the selectivity reached 67.90%under these conditions. |
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