Synthesis Of Metal-Loaded AlPO₄-5 Molecular Sieve Catalysts And Their Catalytic Performance In Glycerol Conversion

The supported catalysts are widely used in the production of many important fine chemicals.In recent years,biodiesel as part of renewable energy has aroused great attention.However,during the production of biodiesel there will be a great amount of glycerol surplus.The catalytic conversion of glycerol into value-added fine chemicals will not only improve the value of glycerol but also extend the industry chain of biodiesel.Zeolite materials obtain large surface area,regular pore size and high thermal stability,zeolite materials appear as promising support for preparing high dispersion supported catalysts.Aluminum phosphate molecular sieve AlPO₄-5 own 12-membered pore channel?0.73 nm?,high thermal stability and possess the similar properties of zeolite materials.To the best knowledge of us,there are few reports about using AlPO₄-5 as support for preparing supported catalysts in catalytic conversion of glycerol.In order to obtain high dispersion supported catalyst,in this paper we have developed a strategy to obtain supported catalysts by using metal-complex as precursor during the synthesis of AlPO₄-5 and obtain?Pt/AlPO₄-5,Ni@AlPO₄-5?catalysts.The structure and properties of the two catalysts were characterized by XRD,TEM,XPS and nitrogen adsorption-desorption.The catalytic performance for glycerol conversion was systematically studied by comparing with the traditional catalyst preparation method.The main contents and conclusions are as follows:?1?By using porous AlPO₄-5 as support the effect of different loading method?impregnation method,precipitation method and sol-immobilization method?on the structure and catalytic properties of Pt/AlPO₄-5 catalyst was investigated,the amount of platinum loading,reaction time and reduction method on the catalytic results were studied at the same time.The results show that Pt/ Al PO4-5 prepared by impregnation method own higher catalytic activity?27.82%?and glyceraldehyde selectivity?50.02%?compared to the catalyst prepared by precipitation method and sol-immobilization method.The larger Pt nanoparticles are more favorable for the formation of glyceraldehyde.?2?Pt/AlPO₄-5 was successfully synthesized by the method of solid-phase grinding using pseudoboehmite supported platinum ions as precursors.The catalyst Pt/AlPO₄-5 was prepared by removing the organic template during pyrolysis.The effects of platinum loading and reaction time on the catalytic oxidation of glycerol were systematically studied.The results show that the Pt / AlPO₄-5 catalyst prepared by solid phase grinding method has a higher selectivity for glyceraldehyde?70.06%?than that of the traditional Pt loading method.?3?The AlPO₄-5 molecular sieve containing Ni-amine complex was synthesized by hydrothermal method using Ni?deta?2Cl2 as template.The Ni?II?occluded in the pores can be directly reduced by reducing gases in situ generated from the decomposition of organic precursors of AlPO₄-5 during heat treatment under N2 atmosphere.TEM and nitrogen adsorption-desorption showed that most of the Ni nanoclusters were highly dispersed into the pore channels of AlPO₄-5,Compared to the catalyst prepared via a conventional impregnation method?Ni/AlPO-5?,the Ni@AlPO-5 catalyst showed significantly higher selectivity for 1,2-propanediol?92.68%?in the hydrogenolysis of glycerol.