Investigation On The Preparation And Properties Of 3DOM Bulk Catalyst For Hydrodesulfurization

The quality improvement of transport fuels is crucial to address the tough challenge of air pollution issues and the current drastic environment regulations all over the world.Chinese government promulgated the National VI Gas Standard from the year of 2019with the regulation of low sulphur content?<10 ppm?.Compared to the oxidation-and adsorption-desulfurization,the hydrodesulfurization?HDS?process is still the main hydrotreating technique for transportation fuels due to the high efficiency in the removing sulfur compounds.Therefore,future research studies should still focus on the improving conventional supported catalysts or searching novel catalyst with superior performance for HDS process.In this work,novel bulk hydrodesulfurization catalyst with three-dimensionally ordered macroporous?3DOM?structure were successfully fabricated.Firstly,the factors of emulsion polymerization for the preparation of poly-?methyl methacrylate??PMMA?,including the mass ratio of monomer to water,initiator,emulsifier,stirring speed,and reaction temperature were intensively investigated.The PMMA templates with a particle size of 220-260nm were successfully fabricated when the mass ratio of monomer to water was 4%,and the amount of initiator was 0.2g,the amount of emulsifier was 0.0028-0.0036g,the stirring speed was 350rpm,and the reaction temperature was 70oC.The microstructure tuning of bulk catalysts would significantly influence their physical and chemical properties.The?3DOM?bulk catalysts were successfully fabricated by employing PMMA as hard template.The prepared bulk catalysts were characterized by means of techniques,such as TG/DTG,XRD,low-temperature N₂adsorption-desorption,SEM,TEM,HRTEM,and tested in a continuous high-pressure fixed-bed micro-reactor.The results indicated that the unique hierarchical pore system of the 3DOM bulk catalysts could not only supply more available surface area,thus more active sites,but also facilitate the diffusion of the reactants to the active sites of the bulk catalyst.Moreover,the 3DOM structure of the bulk catalysts was retained after the pre-sulfurization process and hydrodesulfurization reaction,illustrating the relatively high stability of prepared bulk catalysts in the experimental investigation.The 3DOM CoMo bulk catalyst exhibited superior catalytic performance with thiophene conversion of 99.2%at 360°C,1MPa in comparison with the CoW and CoMoW bulk catalysts.In order to further improve the catalytic performance of the 3DOM bulk CoMo catalyst,the surfactants PEG 400 and F127 were introduced to synthesize the 3DOMM bulk CoMo catalyst with a nanovoid structure.The catalyst performance tests indicated that the CoMo-PF-1 bulk catalyst shows the best catalytic performance with thiophene conversion of 99.4%at 360°C,1MPa when the PEG400/F127 molar ratio was 35.2/1.This is because the catalyst had a mesopore structure of 2-4nm,and the catalyst active phase MoS₂ exhibited a good dispersion and moderate stacks.