微孔-双介孔核壳型HZSM-5@BMMs催化甲醇芳构化

Studies on the Micro-bimodal Mesoporous Core-shell HZSM-5@BMMs Catalyst for the Methanol to Aromatics

摘要:

摘要：采用外延法，以HZSM-5为核，双介孔分子筛BMMs为壳制备了多级孔核壳型HZSM-5@BMMs甲醇芳构化(MTA)催化剂。采用XRD、BET、NH3-TPD、SEM和TEM对催化剂进行了表征。结果表明：HZSM-5@BMMs具有明显的核壳结构和微孔-双介孔多级孔孔道，孔径集中分布于0.9、2.2和5.3 nm，其比表面积（510.8 m2/g）和孔容（0.399 cm3/g）均高于HZSM-5的比表面积（408.4 m2/g）和孔容（0.190 cm3/g），而酸量（0.573 mmol/g）和酸强度均低于HZSM-5的酸量（0.883 mmol/g）和酸强度。将HZSM-5@BMMs应用于甲醇芳构化反应，相同反应条件下HZSM-5@BMMs寿命比HZSM-5增加38 h，最高芳烃收率为25.7%，最高BTX（轻质芳烃：苯、甲苯、二甲苯）选择性为55.3%。

Abstract:

Abstract: A hierarchical porous HZSM-5@BMMs catalyst for the methanol to aromatics (MTA) was synthesized by epitaxial growth of the bimodal mesoporous silica shell on the core HZSM-5 zeolite. This catalyst was characterized with XRD, BET, NH3-TPD, SEM and TEM. The results indicated that HZSM-5@BMMs has the clear core-shell structure and the micro-bimodal meso porous structure, its pore size mainly distributed at 0.9, 2.2 and 5.3 nm. Compared with the HZSM-5, the specific surface area and the pore volume of HZSM-5@BMMs (510.8 m2/g, 0.399 cm3/g) are higher than those of HZSM-5 (408.4 m2/g, 0.190 cm3/g). However, the acid amount (0.573 mmol/g) of HZSM-5@BMMs is lower than HZSM-5 (amount is 0.883 mmol/g). The change of acid intensity is the same as this. The catalyst was applied in MTA, it was shown that the longevity of HZSM-5@BMMs in MTA under the same condition is 38 h longer than that of HZSM-5, and the highest yield of aromatics and the selectivity of BTX ( lightweight aromatics: benzene, toluene, xylene) on HZSM-5@BMMs were 25.7% and 55.3% respectively.