Mg/HZSM-5分子筛催化甲醇与1-丁烯偶合制丙烯

采用水热法合成纳米和微米尺寸的HZSM-5分子筛,并用浸渍法负载Mg对纳米HZSM-5分子筛进行改性,通过XRD、SEM、N_2等温吸附-脱附、NH_3-TPD和TGA对分子筛进行表征,并将其用于甲醇与1-丁烯偶合制丙烯反应,考察分子筛晶粒尺寸、Mg负载量、反应温度、空时和甲醇与1-丁烯物质的量比对催化剂反应性能的影响。结果表明,纳米HZSM-5分子筛具有比表面积大、孔道短和孔口多等特点,表现出较好的活性和稳定性及较强的容碳能力。利用Mg对纳米HZSM-5进行改性,提高了HZSM-5分子筛上原料的转化率和丙烯收率,在反应温度550℃、反应压力0.1 MPa、空时1.6 gcat·(h·mol_(CH_2))~(-1)和甲醇与1-丁烯物质的量比为3的条件下,1%Mg/HZSM-5分子筛催化剂上的丙烯收率最高,达41.8%,比未改性的纳米HZSM-5分子筛催化剂提高9.7个百分点。

Coupling conversion of methanol and 1-butylene to propylene on Mg/HZSM-5 zeolite catalysts

Nano-sized and micro-sized HZSM-5 zeolites were synthesized by hydrothermal method.Mg-modified nano-sized HZSM-5 zeolites were prepared by impregnation method.The catalysts were characterized by XRD,SEM,N2 isothermal adsorption-desorption,NH3-TPD and TGA techniques,and tested in the coupling conversion of methanol and 1-butylene to propylene.The influences of particle size,Mg-loadings,reaction temperatures,space time and methanol/1-butylene molar ratios on the catalytic performance of the catalysts were investigated.The results showed that nano-sized HZSM-5 catalyst exhibited better catalytic reactivity,stability and coke capacity than micro-sized HZSM-5 catalyst due to its larger specific surface area,shorter channels and more exposed pores,etc.The appropriate amount of Mg modification could improve the conversion of reactants and propylene yield.Under the condition of reaction temperature 550 ℃,reaction pressure 0.1 MPa,space time 1.6 gcat·(h·molCH₂)-¹ and methanol/1-butylene molar ratio 3,1%Mg/HZSM-5 had the highest propylene yield of 41.8%,9.7 percentage points than the unmodified nano-sized HZSM-5 catalyst.