摘要
采用水热法合成了SAPO-5、SAPO-11、SAPO-41分子筛,并以间二甲苯异构化反应为模型反应,考察了SAPO-5、SAPO-11、SAPO-41的催化性能;运用XRD、BET、吸附吡啶的FT-IR等手段表征了SAPO的结构和酸性。结果表明,在合成投料比相同的情况下,SAPO-11具有最大的较强B酸量,表现出了最好的间二甲苯异构催化活性。SAPO-5因为较强B酸中心数目少,异构催化活性最差。三种分子筛的间二甲苯异构化催化活性和较强B酸中心的分布均呈SAPO-5<SAPO-41≈SAPO-11顺序排列。较强B酸中心的分布是决定催化剂异构化活性的主要因素。中孔分子筛SAPO-11、SAPO-41孔道直径与对位产物的直径接近,对位选择性比大孔分子筛SAPO-5好。
Silicoaluminophosphate molecular sieves SAPO-5, SAPO-11 and SAPO-41 were synthesized and characterized by XRD, IR and pyridine adsorption IR. Their catalytic performances in isomerization of m-xylene were investigated. SAPO-11 owns the largest number of acid sites, particularly the strong Broensted acid sites, and then exhibits the highest activity and selectivity to p-xylene; whereas low activity and selectivity were obtained over SAPO-5 catalyst. The sequence of activity and the number of strong Broensted acid sites of the SAPOs followed SAPO-5 〈 SAPO-41 ≈ SAPO-11. Both SAPO-11 and SAPO-41 produce predominantly the p-xylene isomer due to their medium size pores.
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
2006年第6期740-744,共5页
Journal of Fuel Chemistry and Technology
关键词
SAPO
异构化
B酸
孔道结构
SAPO
isomerization
Broensted acid sites
pore opening
xylene
