干凝胶法合成多级孔SAPO-11分子筛及其异构化性能

分别以拟薄水铝石、硅溶胶和磷酸为铝源、硅源和磷源，二正丙胺和二异丙胺为模板剂，在单独或同步添加十六烷基三甲基溴化铵（CTAB）与聚乙二醇（PEG）的条件下，利用干凝胶法制备了多级孔道SAPO-11分子筛。采用XRD、氮气物理吸脱附、SEM、NH₃-TPD和Py-IR等手段对合成的SAPO-11分子筛进行表征，并于固定床上考察制备的Pt/SAPO-11分子筛在正十二烷异构化反应中的催化性能。结果表明，在干凝胶合成SAPO-11的体系中添加CTAB与PEG，促使分子筛中生成介孔结构，并使其形貌及酸强度发生变化，合成的多级孔SAPO-11催化剂对正十二烷加氢异构选择性和收率显著优于微孔SAPO-11分子筛，其中Hier-Sapo-11-cp分子筛在340 ℃时的异构烷烃选择性与收率分别达到71.2%和62.1%。

Synthesis of Multistage Pore SAPO-11 Molecular Sieve by Dry Gel Method and Its Isomerization Performance

The porous SAPO-11 molecular sieves were prepared by dry-gel method under the condition of single or simultaneous addition of cetyltrimethylammonium bromide (CTAB) and polyethylene glycol (PEG), respectively, with pseudoboehmite, silica sol and phosphoric acid as aluminum source, silicon source and phosphorus source, dipropylamine and diisopropylamine as template. The synthesized SAPO-11 molecular sieves were characterized by XRD, nitrogen physical adsorption and desorption, SEM, NH₃-TPD and Py-IR. The catalytic performance of the prepared Pt/SAPO-11 molecular sieve in n-dodecane isomerization reaction was investigated on a fixed bed. The results show that the addition of CTAB and PEG in the dry gel synthesis of SAPO-11 can promote the formation of mesoporous structure in the molecular sieve and change its morphology and acid strength. The selectivity and yield of the synthesized multistage pore SAPO-11 catalyst for n-dodecane hydroisomerization are significantly superior to those of the microporous SAPO-11 molecular sieve. The selectivity and yield of isoparaffin of Hier-Sapo-11-cp molecular sieve reach 71.2% and 62.1% respectively at 340 ℃.