DEA/TEAOH templated synthesis and characterization of nanostructured NiAPSO-34 particles:Effect of single and mixed templates on catalyst properties and performance in the methanol to olefin reaction

摘要

A nanostructured NiAPSO-34 catalyst was hydrothermally synthesized and the effect of the template(diethylamine(DEA),tetraethylammonium hydroxide(TEAOH) and DEA/TEAOH) on the physicochemical properties and catalytic performance in the methanol to olefin(MTO) reaction was investigated.The samples were characterized by X-ray diffraction,field emission scanning electron microscopy(FESEM),particle size distribution analysis,energy-dispersive X-ray spectroscopy,Brunauer-Emmett-Teller analysis and Fourier transform infrared spectroscopy.The X-ray diffraction patterns indicated a higher crystallinity and larger crystallite size for the catalyst synthesized using the DEA template.The FESEM results indicated that the nature of the template could affect the morphology of the nanostructured NiAPSO-34 catalyst because of its effect on the rate of crystal growth.The catalytic performance of the samples was studied in the MTO reaction at atmospheric pressure and a space velocity of 4200 cm^3/(g h^(-1))in a fixed bed reactor.The stability and activity of the NiAPSO-34 catalyst were improved using the DEA template because of its higher crystallinity,surface area and the greater extent of Ni incorporation into its framework.The possible stages of synthesis and the reaction mechanism for the MTO process over NiAPSO-34 are discussed in detail.