改性对分子筛酸性和烷基化脱硫性能的影响

The Effects of Modification on the Surface Acidity of Zeolite and Alkylation Activity of Thiophenic Derivative With Olefins

对Na型分子筛分别进行不同性质的阳离子交换和热处理,得到了HY,USY,CeY,MgY,Hβ和USβ系列改性分子筛催化剂,并考察了改性分子筛催化FCC汽油烷基化脱硫的活性。通过吡啶吸附红外光谱表征,研究了改性对分子筛的表面酸性和催化活性的影响规律。结果表明,铵改性Y分子筛的酸量远远大于β分子筛。USY的B酸量、L酸量分别增大到了868.583,972.869μmol/g,其中L酸主要以弱酸的形式存在。USβ的B酸量、L酸量也有所增加,但是强B酸量降低,强L酸量增加。Mg2+改性后的NaY分子筛总酸仅次于HY,但强B酸量仅为86.742μmol/g,强L酸量仅为31.335μmol/g;Ce3+改性后的NaY分子筛总B酸量和强B酸量仅次于USY,L酸量仅为58.308μmol/g,但无强L酸。结合小于100℃馏分段硫的转化率得出,总B酸量越多,且强B酸量越多(HY除外),小于100℃馏分段硫的转化率越高。强L酸不利于噻吩类硫化物的烷基化反应。对于β分子筛,强B酸中心是烷基化反应的主要活性位。

Zeolite NaY and Naβ were modified by cation exchange and hydrothermal treatment to make a series of modified catalysts, including HY, USY, CeY, MgY, Hβ and USβ. The catalytic activities of the modified catalysts for the alkylation of thiophenic derivative with olefins in FCC gasoline were investigated. The surface acidity of modified zeolite had been studied by FT--IR. The results show that Y zeolite exchanged by ammonium have much more acid than β zeolite. The volume of B acid and L acid of USY increased to 868. 583 μmol/g and 972. 869 μmol/g , while L acid is mainly in the form of weak acid. The volumes of B acid and L acid of USI3 also increase with the decreasing of strong B acid and increasing of strong L acid. The volume of total acid of MgY is slightly lower than HY, but with only 86. 742 μmol/g strong B acid and only 31. 335 μmol/g strong L acid. The volumes of total B acid and strong B acid of CeY are slightly lower than USY, with only 58. 308 μmol/g total L acid and non of strong L acid. Through the analysis of surface acidity of zeolite and alkylation activity, it shows that the more total B acid and strong B acid （except HY）, the higher conversion of sulfur compounds below 100 ℃ fraction of FCC gasoline. Strong L acid is not conducive to the alkylation. The strong B acid is the main active site of alkylation.