摘要
以MgFeZn-HTLcs为前驱体,制备了不同Mg/Fe/Zn物质的量配比、K改性的K/MgFeZn-HTLcs催化剂,用于CO加氢直接制低碳烯烃反应。采用N2吸附-脱附、SEM、TG、XRD、XPS、H_2-TPR等手段对催化剂进行了表征。结果表明,MgFeZnHTLcs前驱体具有典型的层状结构,孔径分布均一;经焙烧、K改性后仍具有一定的层状结构,但比表面积显著减小,平均孔径增大;新鲜催化剂物相以金属氧化物和铁酸盐为主,反应后K/MgFeZn-HTLcs催化剂主要以Fe_5C_2、MgCO_3和ZnO相存在,K/2Fe-1Zn催化剂主要物相为ZnFe2O_4。在CO加氢反应中,K/MgFeZn-HTLcs催化剂具有较高的C=2-4烯烃选择性和较低的C+5含量,与K/2Fe-1Zn催化剂相比,产物分布明显改善;K/2Mg-2Fe-1Zn催化剂上O/P比值达5.15,C=2-4含量占总烃质量的48.56%。
A series of K promoted K /MgFeZn-HTLcs catalysts with different Mg / Fe / Zn molar ratios were prepared by means of precipitation method and impregnation method for the direct synthesis of light olefins from CO hydrogenation. The samples were characterized by N2adsorption-desorption SEM,TG,XRD,XPS and H2-TPR measurements. The results showed that theMgFeZn-HTLcs catalyst precursors have typical lamellar structure,larger specific surface area and average pore diameter compared with Fe / Zn catalyst. The BET surface area and the average pore diameter decreased after calcination and K promotion. The bulk composition of the calcined samples was mainly metal oxide and ferrite. Fe_5C_2,MgCO_3 and Zn O were formed in K /MgFeZn-HTLcs catalysts after reaction. However,the main phase in K / 2Fe-1Zn catalyst was stabilized in ZnFe2O_4. During CO hydrogenation,the prepared samples showed high C=2-4selectivity and lowC＋5weight fraction compared with that of K / 2Fe-1Zn sample. The product distribution was greatly improved. Over the sample K / 2Mg-2Fe-1Zn,an olefin to paraffin ratio of 5.15 and the C=2-4weight olefin content of 48.56% could be obtained.
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
2016年第4期449-456,共8页
Journal of Fuel Chemistry and Technology
基金
宁夏自然科学基金(NZ13010)资助~~
