Studies Of Liquid Flow,Mass Transfer And Hydrogenation Performance In High Gravity Catalytic Reactors

Petroleum refining industry plays an important role in national economy.The development of heavy oil processing technology has become one of the important measures to avoid the risk of oil resources.Hydrogenation and saturation of partial benzene ring of polycyclic aromatic hydrocarbon in heavy oil can not only reduce its toxicity,but also improve its additional value,which has the great significance for slowing down oil dependence and ensuring national energy security.Conventional fixed bed reactors are mostly applied for hydrogenation reaction.However,there are some problems such as nonuniform fluid distribution,low mass transfer efficiency and high pressure drop in these reactors.The high gravity rotating packed bed is one of the typical reactors for chemical process intensification,and is suitable for multiphase reaction processes to intensify interphase mass transfer and molecular mixture.Consequently,a new method is proposed to intensify the hydrogenation of polycyclic aromatic hydrocarbon by a high gravity rotating packed bed with catalyst packings in this dissertation.Firstly,the fluid flow state of the packed and monolithic support packings was investigated to explore the intensification mechanism of mass transfer and reaction processes.Then the mass transfer characteristics in the rotating packed bed with two types of support packings were verified by chemical absorption system.The preparation of monolithic catalyst support and impregnation of monolithic catalyst active components were developed and optimized.Finally,the hydrogenation performance of polycyclic aromatic hydrocarbon in the rotating packed bed with two types of catalyst packings were investigated,compared and evaluated.The main research contents are as following:(1)The state of liquid flow through a single Al2O3 sphere catalyst support was observed by a high speed camera.The behavior of liquid adsorption of Al2O3 sphere was investigated by ink adsorption method.The kinetics of liquid adsorption process of Al2O3 sphere was analyzed.(2)NaOH-CO2 chemical absorption system was employed to investigate the variation of mass transfer performance in the rotating packed bed with the packed support packing.The volumetric liquid-side mass transfer coefficient per unit gas pressure drop was compared,and the effect of packed type on the mass transfer performance in the rotating packed bed was comprehensively evaluated.(3)For the preparation of monolithic catalyst support,HCl and HNO3 mixed acid solution were employed to pretreat the surface of stainless steel platelet and the inner surface of stainless steel tubule by chemical etching.A method for obtaining different roughness and pore size on the substrate surface by changing acid concentration and etching time was proposed.Al2O3 was coated on the surface of the pretreated substrate by sol-gel method.The matching relation between the pores of substrate surface and the particles of Al2O3 support was revealed,and the effect of this coating process on the performance of Al2O3 was evaluated by characterization analyses.(4)The preparation method for monolithic catalyst support was applied to the stainless steel wire mesh.The wetting state of the single fiber surface after the droplet dropping and impacting on the fiber was photographed by the high speed camera.The liquid spreading length and contact angle were measured.Then NaOH-CO2 chemical absorption system was employed to investigate the variation of mass transfer performance in the rotating packed bed with the monolithic support packing,and the volumetric liquid-side mass transfer coefficient per unit gas pressure drop was compared.(5)The active components were impregnated on the monolithic support packing by wet impregnation method,and the optimum impregnation conditions were determined.The packed and monolithic catalysts were presulfided by ex-situ presulfurization and two-step presulfurization method.The hydrogenation of tetralin(polycyclic aromatic hydrocarbon)to decalin was employed as the research system.The hydrogenation performance in the rotating packed bed with the packed and monolithic catalyst packings was investigated,and the intensification effect in the hydrogenation reaction was evaluated by comparison.