硅改性Hβ沸石催化萘异丙基化反应

Isopropylation of Naphthalene over Silicon-Modified Hβ Zeolite Catalyst

采用化学液相沉积法对Hβ沸石进行硅改性,并对其催化萘异丙基化反应的性能进行了评价,考察了硅油类型、沉积量和沉积时间对硅改性Hβ沸石催化性能的影响;采用BET、X射线衍射、吡啶吸附-红外光谱和氨吸附-程序升温脱附等方法对Hβ沸石的晶相、孔结构和酸性进行了表征。实验结果表明,采用该方法可在基本不改变Hβ沸石骨架结构、内孔孔体积和内表面性质的前提下,有效钝化Hβ沸石外表面的酸性位,提高Hβ沸石催化萘异丙基化反应的性能。黏度为100mm2/s的硅油是较好的硅改性剂,在硅油沉积量为0.4mL/g、沉积时间为12h时,可达到较好的改性效果,在此条件下进行硅改性对Hβ沸石的孔口有一定的修饰作用,提高了它的择形催化效果,同时还可提高萘的转化率及二异丙基萘和2,6-二异丙基萘的收率,萘的转化率达82.47%,二异丙基萘和2,6-二异丙基萘的收率分别达到33.80%和8.35%。

Silicon- modified Hβ zeolites were prepared by chemical liquid- phase deposition of silicon oil. Isopropylation of naphthalene with isopropanol was carried out on the modified Hβ zeolite catalysts. Influences of silicone oil types, its dosage and deposition time on performances of the catalysts were investigated. The silicon -modified Hβ zeolite catalysts were characterized by means of XRD, BET, Py -IR and NH3 -TPD. After silicon modification, the structural framework, pore volume and internal surface properties of the zeolites kept essentially unchanged but specific surface area and number of acid sites on external surface of the zeolites decreased. Under optimal condition： viscosity of silicone oil 100 mm^2/s, its dosage 0.4 mL/g, and deposition time 12 h, conversion of naphthalene, and yields of diisopropylnaphthalene（DIPN） and 2,6 - DIPN on the prepared modified catalyst obviously increase in comparing with the unmodified. Fine modification of Hβ zeolite pore opening leads to improvement of shape - selectivity of the catalyst. Naphthalene conversion and yields of DIPN and 2,6 - DIPN can reach 82.47% ,33.80% and 8.35% ,respectively.