Fe-Al-P-O催化1,2-二氯丙烷与水环氧化制环氧丙烷反应机理

 采用溶胶-凝胶法制备了非晶态Fe-Al-P-O催化剂,并用IR,XRD,TEM,N2吸附及微反等技术对其组成、结构特性以及催化性能进行了表征和评价,通过IR和TPD-MS等技术着重研究了其化学吸附性能,探讨了表面催化反应的机理. 结果表明,Fe-Al-P-O催化剂是FePO4和AlPO4均匀混合形成的非晶态混合物,能够促进1,2-二氯丙烷和水反应高选择性地生成环氧丙烷,其Lewis酸位的Fe3+和Lewis碱位P=O的O2-是催化剂表面的主要活性位,能使水进行解离吸附并形成Fe-O-和P-OH 键. 1,2-二氯丙烷通过Cl-与P-OH键中的H+作用形成桥式吸附态是反应进行的关键.

Mechanism of Epoxidation of 1,2-Dichloropropane with Water to Produce Propylene Oxide Catalyzed by Fe-AI-P-O

The non-crystal Fe-Al-P-O catalyst was prepared by the sol-gel method and used to synthesize propylene oxide (PO) from 1,2-dichloropropane (DCP) and H_2O. The catalyst composition, structure and catalytic behavior were characterized and evaluated by infrared spectroscopy (IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), N_2 adsorption and microreactor. The reaction mechanism was studied by chemisorption-IR and temperature-programmed desorption-mass spectroscopy (TPD-MS). The results show that the Fe-Al-P-O catalyst is a non-crystal mixture of FePO_4 and AlPO_4 and can effectively promote the aim reaction with high selectivity for PO. Lewis acid sites Fe 3+ and Lewis base sites O 2- in PWTBZ]KG-45x]=KG-20x]O bonds are the main active sites on the catalyst surface, on which H_2O can be chemisorbed and dissociated to form PKG-45x]-KG-20x]OH and FeKG-45x]-KG-20x]O-species. Through the interaction of Cl-and PKG-45x]-KG-20x]OH, DCP can be chemisorbed to form a bridge chemisorption state, which is the key step in the reaction. Propylene adsorbed on O-of the FeKG-45x]-KG-20x]O-bond is a useful intermediate for the PO production.