Zn改性SAPO-34/HZSM-5复合分子筛及其催化甲醇芳构化性能研究

Zn modified SAPO-34/ HZSM-5 composite molecular sieve and its performance for methanol aromatization reaction

采用机械混合法制备SAPO-34/HZSM-5复合分子筛,以浸渍法向复合分子筛引入Zn助剂对其进行改性,借助X射线衍射(XRD)、N2吸附-脱附、NH3程序升温脱附(NH3-TPD)、吡啶吸附红外光谱(Py-FTIR)和程序升温氧化(TPO)等手段对改性前后的复合分子筛进行表征。结果表明,Zn助剂的引入对复合分子筛的晶体结构、孔径影响较小,对复合分子筛的表面酸性影响较大。与改性前相比,改性后的复合分子筛的反应稳定性略差。最后,将Zn改性前后的复合分子筛用于甲醇芳构化反应,考察其芳构化性能。结果表明,Zn改性的SAPO-34/HZSM-5复合分子筛具有较好的芳构化活性。在反应温度为460℃、反应压力0.5 MPa、空速(LHSV)1.2 h-1条件下,BTX(苯、甲苯和二甲苯)的收率可达40.8%。

SAPO-34 / HZSM-5 composite molecular sieves was synthesized by mechanical mixing method.Then the composite molecular sieves were modified by the addition of Zn through impregnation. XRD,N2adsorption-desorption,NH3-TPD,Py-FTIR and TPO techniques were used to characterize the catalysts.The results showed that the addition of Zn had little influence on the skeletal structure and pore structure,but could change the surface acidity of catalysts. In addition,the catalytic performance of catalysts for the aromatization of methanol were studied. The results showed that SAPO-34 / HZSM-5 composite molecular modified by Zn has better aromatization activity. In reaction temperature 460 ℃,pressure is 0. 5 MPa,airspeed( LHSV) 1. 2 h-1,under the condition the yield of BTX( benzene,toluene and xylene) can reach40. 8%.