摘要:
比较了Hβ沸石、树脂、ZSM-5沸石等常用于丙烯醚化合成二异丙醚（DIPE）催化剂的性能，考察了助剂对Hβ沸石孔结构、酸度及催化活性的影响。结果表明，Hβ沸石上丙烯醚化合成DIPE的催化活性优于ZSM-5沸石，而树脂催化剂可催化丙烯水合生成异丙醇（IPA）反应。TiO2、ZrO2、碱土金属、稀土元素和VB族元素均使Hβ沸石的B酸中心减少，L酸中心增多。总酸量较大、L酸中心较多的催化剂，更有利于DIPE的生成。孔性质对催化剂活性的影响较小。TiO2可以大幅度提高DIPE选择性和时空产率，对提高丙烯转化率并无贡献。ZrO2可提高DIPE选择性、丙烯转化率和DIPE的时空产率，副产丙酮，且C6杂质较多。同时添加一种碱土金属、一种稀土元素和一种VB族元素制备的Hβ沸石催化剂具有较好的合成DIPE活性，在165℃、7.0 MPa、水/丙烯摩尔比0.5和LHSV 0.5h－1时，DIPE的初始收率达到39%。运转1 000 h后，DIPE收率仅下降了3%。
Abstract:
The catalytic properties of Hβ, ZSM-5 zeolites and resin were compared in propylene hydration-etherification to produce diisopropyl ether (DIPE). The influence of promoters (both type and amount) on the Hβ zeolite pore structure, acidity and activity was examined. The results showed that the etherification property of Hβ is superior to ZSM-5; Hβ zeolite is suitable for etherification reaction, while resin has advantage in hydration reaction to product IPA. As the promoters of Hβ zeolite, TiO2, ZrO2, the alkaline-earth metal, the rare-earth elements and the VB elements can reduce the amount of Bronsted acid on Hβ zeolite, but increase the amount of Lewis acid on Hβ zeolite. Larger amounts of Lewis acid and total acid on Hβ zeolite can benefit the production of DIPE, but the pore structure has less influence on it. TiO2 can increase DIPE selectivity and yield, but contribute nothing to propylene conversion; ZrO2 can enhance DIPE selectivity, propylene conversion and DIPE yield，but can produce also more by-products such as acetone and C6; Adding the alkaline-earth metal, the rare-earth elements and the VB elements simultaneously can improve catalytic activity of Hβ zeolite obviously. At a suitable operating conditions (165 ℃, 7.0 MPa, n(water)/n(propylene) ratio of 0.5 and a LHSV of 0.5 h－1, the initial yield of the catalyst made by adding these elements could reach 39% at optimum conditions, and decreased by 3% after running for 1 000 h.
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