合成条件对SAPO-11分子筛性质及催化性能的影响

IMPACT OF WATER AMOUNT AND SEED CRYSTAL ON SAPO-11 MOLECULAR SIEVE SYNTHESIS AND ISOMERIZATION PERFORMANCE

通过调变SAPO-11分子筛合成的水/铝比[n(H_(2)O)/n(Al_(2)O_(3))]、晶种添加量、晶化温度,合成了系列SAPO-11分子筛,研究合成条件对SAPO-11分子筛物化性质及其催化1-己烯临氢异构化性能的影响。结果表明:适当提高体系水/铝比,可使SAPO-11分子筛晶化时产生优先生长现象,从而暴露出更多孔口,提高分子筛的催化性能;加入异质晶种可以缩小SAPO-11分子筛的粒径,提高分子筛的比表面积、孔体积与酸量;与其他条件下合成的分子筛相比,在高水/铝比、添加异质晶种、高晶化温度下合成的SAPO-11-seed-200分子筛的粒径最小、比表面积和孔体积最大、酸量最高,催化1-己烯临氢异构化反应比合成的其他分子筛具有更优的催化活性和更高的骨架异构选择性。

A series of SAPO-11 molecular sieves were synthesized by adjusting the n(H_(2)O)/n(Al_(2)O_(3))ratio,the amount of seed crystals addition and crystallization temperature in the SAPO-11 molecular sieve synthesis process,and the effects of synthesis conditions on the physicochemical properties of molecular sieves and the catalytic performance in 1-hexene hydroisomerization were studied.The results show that the preferential growth of SAPO-11 molecular sieves can be obtained by increasing ratio of n(H_(2)O)/n(Al_(2)O_(3)),thus exposing more pores and improving the catalytic performance,and the size of SAPO-11 molecular sieve can be reduced by adding heterogeneous crystal seeds.Compared with the molecular sieves synthesized under other conditions,the specific surface area,pore volume and acid content were increased.The SAPO-11-seed-200 molecular sieves synthesized at high n(H_(2)O)/n(Al_(2)O_(3)) ratio,heterogeneous seeds and high crystallization temperature had the smallest particle size,the largest specific surface area and pore volume,and the highest acid amount.The catalytic activity and the skeletal isomerization selectivity of 1-hexene isomerization were better than those of other molecular sieves.