孔结构和酸性对纳米HZSM-5分子筛催化生物乙醇制丙烯反应性能的影响

对纳米HZSM 5分子筛分别进行NaOH处理、Mg改性以及两者的复合改性。采用N2吸附 脱附、 XRD、27Al MAS NMR、NH3 TPD和TGA等技术手段对改性前后样品的结构、织构和酸性进行表征，并采用微型固定床反应器，在常压、500℃和乙醇质量空速(MHSV)为33 h-1的条件下，考察其催化生物乙醇制丙烯反应的性能。结果表明，对纳米HZSM 5分子筛复合改性时，第1步的NaOH溶液处理使分子筛的孔道结构得到修饰，使后续Mg改性过程中有更多的乙酸镁自配物进入分子筛孔道，对其内表面的强酸位改性。这样复合改性的纳米HZSM 5〖JP2〗分子筛在催化乙醇制丙烯反应中可有效抑制孔道内发生积炭等副反应，从而提高丙烯选择性，其稳定性也明显改善。

Effects of Pore Structure and Acidity of Nano-HZSM-5 on Its Catalytic Performance for the Conversion of Bio-ethanol to Propene

 A series of modified nanosized HZSM 5 zeolites were prepared by NaOH treatment, Mg modification and composite modification of both. These catalysts were characterized by N2 adsorption desorption, XRD, 27Al MAS NMR, NH3 TPD and TGA. Their catalytic performance for selective conversion of bio ethanol to propene was tested by using a continuous flow fixed bed micro reactor at atmospheric pressure, 500℃ and ethanol mass hourly space velocity (MHSV) of 33 h-1. The results showed that in the composite modification of nanosized HZSM 5 by NaOH treatment and Mg modification, the porous structure of zeolite was modified under the first step of NaOH solution treatment, which enabled more amounts of the magnesium acetate to enter the micropores of zeolite to adjust the strong acid located in the internal surface during the consequent step of Mg modification. With the co modified nanosized HZSM 5 as catalyst the propene selectivity of bio ethanol conversion to propene was noticeably enhanced, at the same time, the catalyst stability was improved.