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Research on Preparation and Properties of Hydrodeoxygenation Catalysts

Author: ZhouEnShen
Tutor: YangYunQuan
School: Xiangtan University
Course: Chemical Engineering
Keywords: hydrodeoxygenation CoMo bimetal nitride amorphous catalyst Mo-O-B
CLC: TE624.9
Type: Master's thesis
Year: 2009
Downloads: 117
Quote: 2
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Abstract

With the rapid economic development of our country, the contradiction between the relative lack of oil resources and the rapid rise in the demand for oil has become increasingly prominent, and it’s constraining our sustained economic development and seriously threating the national energy security. In these days, all countries especially the advanced industrial countries in the world are actively committed to the development of a variety of new oil-alternative energy sources such as coal oil, bio-oil to alleviate the situation of oil shortage. However, the primary products of these new alternative energy sources are of high oxygen content (the oxygen content of some Bio-oil can be as high as 50wt%), and for which have the defects such as low heat of combustion, poor stability and corrosive with them. In order to solve this problem, further treatment of catalytic hydrodeoxygenation is needed. In this article, a series of TiO2 supported CoMo nitride catalysts and Mo-O-B amorphous catalysts were prepared, and were characterized using the BET, XRD, SEM, XPS and DSC techniques. The hydrodeoxygenation properties of these catalysts were studied using Phenol as a model compound.Firstly, a series of TiO2 supported oxide CoMo with a variety of Co loadings were prepared by incipient impregnation, and were then temperature reduced in NH3 flow to get the corresponding nitride CoMo/TiO2 catalyst. With the addition of Co, the specific surface area of the catalyst decreased, and a new nitride phase Co3MO3N was produced. The XRD results show that Co3MO3N was formed from the nit riding of a CoMoO4 precursor prepared from Co(NO3)2·6H2O and (NH4)6Mo7O24·4H2O but not from the mixture of CoO and MoO3. The new phase Co3MO3N greatly enhanced the hydrodeoxygenation activity of the catalysts. The catalysts hydrodeoxygenation activity is a result of the combined effects between the composition of the catalyst and its specific surface area, the maximum conversion was reached when the loading of CoO and MoO3 was 4wt% and 12wt% respectively. The phenol hydrodeoxygenation reaction rate constants of nitride catalysts with different Co loadings were found with the following order:Co4Mo12>Co6Mo12>Co2Mo12>Co8Mo12>Co0Mo12>thermal. This study further extended the application of transition metal nitride catalysts at the removing of heteroatom, and added a certain amount of theoretical bases and feasibility proves to the application of transition metal nitrides to the refining process of raw materials such as heavy oils which containing S, N, O heteroatoms at the same time.Two kinds of amorphous alloy catalysts were prepared by chemical reduction process under the condition of ice bath and ultrasonic separately. Characterization results showed that catalysts prepared under these two conditions were both with amorphous structure; The hexavalent molybdenum in the raw materials were only partially reduced under both of these two conditions, and had its valences of +4 and +6 in samples prepared by ice bath method, while the values were found to be +5and +6 in those prepared by ultrasonic method. The formation of Boron oxide was restrained under ultrasonic condition; Respect to the ultrasonic method prepared samples, those prepared by ice bath method possed higher thermal stability and better surface structure, and therefore, almost double activity of hydrodeoxygenation. This study made a new attempt in the search for new hydrodeoxygenation catalysts, and expanded the applications of amorphous catalysts as well.

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