微@介孔复合分子筛的合成及其加氢裂化性能

SYNTHESIS AND HYDROCRACKING PERFORMANCE OF MICRO/MESOPOROUS COMPOSITE ZEOLITE

研究了微@介孔复合分子筛合成过程中TEOS水解状态、酸种类、核分子筛种类及性质等因素对合成产物性质的影响。结果表明,在适宜酸浓度下搅拌6h静置24h时TEOS可最大程度水解成活性Si物种,在核分子筛表面形成有序介孔壳层。合成过程中酸根阴离子作用不同,Cl^(-)有助于复合分子筛比表面积的增加,C_(2)O_(4)^(2-)和NO_(3)^(-)有利于孔体积的增大。Y分子筛或Beta分子筛为核时,核分子筛自身酸量高、酸性强时有助于壳层介孔结构的生成及核壳结构的完整。以十二烷和甲苯为模型化合物,与含单一的Y或Beta分子筛催化剂相比,含复合分子筛催化剂具有更好的中间馏分油选择性,并且催化剂的加氢性能与酸性质、孔结构匹配越好,对甲苯的转化能力越强。

The effects of different factors,such as TEOS hydrolysis state,acid type,core zeolite type and properties,on the product properties during the synthesis process of micro/mesoporous composite zeolite were investigated in this study.The results indicate that TEOS can be hydrolyzed to active Si species when stirred for 6 hours and left to stand for 24 hours at an appropriate acid concentration,subsequently forming an ordered mesoporous shell layer on the surface of the core zeolite.Anions play different roles in the synthesis process.Cl^(-)helps to increase the specific surface area of the composite zeolite,while C_(2)O_(4)^(2-) and NO_(3)^(-) contributes to increase pore volume.When Y or Beta are used as the core zeolite,the high and strong acidity of the core zeolite facilitates the formation of shell mesoporous structure and the integrity of the core-shell structure.Using dodecane and toluene as model compounds,compared with catalysts containing single Y or Beta zeolite,catalysts containing composite zeolite have better selectivity for middle distillate oil in the hydrocracking of dodecane and toluene.The better the hydrogenation performance of the catalyst matches its acidic properties and pore structure,the stronger its ability to convert toluene.