微波水热制备Fe-Zr催化剂及其CO加氢制烯烃性能研究

Preparation of Fe-Zr catalyst by microwave-hydrothermal method and its catalytic performance for the direct synthesis of light olefins from CO hydrogenation

以ZrO(NO3)2·2H2O和Fe(NO3)3·9H2O为原料,采用微波水热法制备了不同Fe2O3/ZrO2物质的量比的Fe-Zr催化剂,并经K改性,研究了其催化CO加氢一步法合成低碳烯烃性能。采用XRD、SEM、TEM和N2吸附-脱附等手段对其物相、形貌和比表面积等进行了表征。结果表明,与共沉淀法相比,微波水热制备的Fe-Zr催化剂颗粒粒径均一,具有相对较小的比表面积和较大的孔径;在CO加氢反应中,Zr助剂的添加显著改善了产物分布,Fe、Zr间适宜的相互作用和相对较大的孔径,有利于抑制CH4的生成,提高烯烃选择性。随着Fe2O3/ZrO2物质的量比的降低,Fe、Zr间相互作用逐渐增强,烯烃选择性和收率先增加后降低。当Fe2O3/ZrO2物质的量比为75∶25时,在340℃、1.5 MPa、1 000 h-1和H2/CO物质的量比为2的条件下,烯烷比(O/P)达4.86,总烯烃收率达62.57 g/m3。

A series of Fe-Zr catalysts with different Fe2O3 / ZrO2 molar ratios were prepared using ZrO（NO3）2·2H2O and Fe（NO3）3·9H2O as raw materials by means of microwave-hydrothermal method. Then,the catalystswere promoted with potassium by impregnation. The samples were characterized by XRD,SEM,TEM and N2 adsorption-desorption methods. The results showed that the catalysts prepared by microwave-hydrothermal method have a narrow particle size distribution,a lower BET specific surface area and a larger pore size comparedwith the traditional precipitation method. During the subsequent CO hydrogenation,it was shown that the productdistribution was significantly improved with the addition of zirconium,and the suitable interaction between Fe-Zrand proper pore size were favorable for inhibiting the methane formation and enhance the olefin selectivity. Withdecreasing the Fe2O3 / ZrO2 molar ratio,the interaction between Fe and Zr was strengthened, and the olefinselectivity and productivity first increased and then decreased. An olefin to paraffin ratio of 4. 86 and light olefinproductivity of 62. 57 g / m3 could be obtained with a Fe2O3 / ZrO2 molar ratio of 75 ：25 under conditions of H2 /CO =2,340 ℃,1. 5 MPa and 1 000 h-1.