无黏结剂HZSM-5沸石催化稀乙醇脱水制乙烯

分别以低硅有黏结剂HZSM-5沸石(硅铝比约30)与无黏结剂HZSM-5沸石为催化剂,考察了它们在稀乙醇脱水制乙烯(ETE)反应中的催化性能。实验结果表明,后者具有较高的活性,且在反应温度低于260℃时,乙烯选择性和收率较高。对比了3种不同骨架硅铝比的无黏结剂HZSM-5沸石催化剂(Z435,Z92,Z31,骨架硅铝比分别为435,92,31)在ETE反应中的催化性能,发现随骨架硅铝比的增加,催化剂的活性降低。分别以HCl溶液、水蒸气及水蒸气-HCl溶液相结合处理的方法对Z31催化剂进行改性,以调节其吸附性质及表面酸量,并对比了不同方法改性的Z31催化剂的活性,发现水蒸气-HCl溶液相结合处理的Z31催化剂的活性最高,在235℃时乙醇转化率达到99.0%,乙烯选择性及收率分别达到98.0%和97.0%。

Dehydration of Diluted Ethanol to Ethylene on Binder-Free HZSM-5 Zeolite Catalyst

Low-silica binder-containing(n(SiO2)∶n(Al2O3) 30) and binder-free HZSM-5 zeolite catalysts were compared in dehydration of diluted hydrous ethanol to ethylene(ETE) process.The latter exhibited higher activity,higher ethylene selectivity and ethylene yield when reaction temperature was lower than 260 ℃.Three kinds of binder-free HZSM-5 zeolite catalysts,with various framework n(SiO2)∶n(Al2O3)(435,92,31,denoted as Z435,Z92 and Z31,respectively),were compared in ETE process,which showed that activity decreased as framework n(SiO2)∶n(Al2O3) increased,and Z31 possessed the highest ethylene selectivity and yield.Z31 catalyst was modified by HCl solution,steaming and steaming combined with HCl solution,in order to adjust adsorptive properties and surface acidity of the catalysts.The catalyst treated with steaming combined with HCl solution is the best in activity in ETE process.Ethanol conversion is 99.0% at 235 ℃,and corresponding ethylene selectivity and yield are 98.0% and 97.0%,respectively.