摘要
1.前言 采用具有ZSM-5,ZSM-11和ZSM-48沸石结构的高硅沸石作为CO加氢反应的催化剂载体,有效地控制了产物分布范围。AlPO_4-5分子筛的孔道结构和表面性质决定了它同样可作为催化剂载体以代替沸石。关于AlPO_4-n分子筛的研究,目前多着重于合成和结构方面,以其作为催化剂和催化剂载体的报道较少。由于AlPO_4-n分子筛无离子交换性,致使负载金属AlPO_4-n催化剂的制备受到限制。根据“某些盐类或氧化物与高比表面载体混合,在低于熔点的适当温度下焙烧,这些盐类或氧化物在载体表面能自发分散”的原理,本文采用固相焙烧法制备了系列Fe_2O_3/AlPO_4-5催化剂并用于CO加氢反应,研究铁活性组分在AlPO_4-5分子筛表面的分散状况及催化活性。
The Fe2O3/AlPO4-5 series catalysts are prepared by the solid thermal treatment, and characterized by X-ray powder diffraction and X-ray photoelectron spectroscopy. The XRD results show that Fe2O3phases in the catalyst can still be detectable as the loading of iron oxide was lowered to 8. 1 wt% for the catalyst calcined only. When the loading is not higer than 20 wt%,α-Fe is the only detected phase on the surface of the catalyst reduced in H2. There is not any iron phases detected in the 17. 7% Fe2O3/AlPO4-5 catalyst during the process of CO hydrogenation. The XPS results indicate that the iron oxides existed on the surface of AlPO4-5 support as both highly dispersive state and aggregative state for the catalyst calcined. In the latter three states of Fe2O3 were found with the binding energies of their Fe2p3/2 lines centered at 713. 0 eV, 711. 1 eV and 710. 0 eV respectively. The appearance of iron lines in the position of high binding energy (Eb= 713. 0 and 711. 1 eV) is the result of the interaction of metal and support in the calcined calalyst. Furthermore, the spreading of the iron phases on the surface occurs while the catalyst is reduced in H2and used in CO hydrogenation. The strong interaction between metal and support affects the dispersion of Fe2O3 on the surface of AlPO4-5. The hydrogenation of carbon monoxide over the Fe2O3/AlPO4-5 catalyst has been investigated at medium pressured. 15×l06Pa) and 598 K. However, the pore structure of AlPO4-5 still limited the carbon chain growth of the products. The catalytic behavior of the catalysts studied is affected by the interaction between the support and the active phase of the catalysts.
出处
《分子催化》
EI
CAS
CSCD
1992年第6期472-476,共5页
Journal of Molecular Catalysis(China)
关键词
催化剂
氢化
钴
Fe2O3/AlPO4-5 catalyst, Solid state reaction, CO hydrogenation.
