Preparation Of Microwave Assisted Hydrodesulfurization Catalyst And Its Desulfurization Performance

With the aggravation of global environmental problems,countries of all over the world have formulated strict vehicle gasoline standards,and the production of ultra-low sulfur clean fuel oil has become an inevitable trend.At present,conventional alumina-based catalysts can not meet the ultra-low sulfur content standard.In order to achieve the purpose of deep desulfurization,it is urgent to develop high-performance deep desulfurization catalysts.Based on this,the effects of active components,support and the modifiers of the catalysts as well as the introduction of microwave electric field on the prparasion of the Co Mo catalyst were investiaged,high-performance hydrodesulfurization catalyst was prepared based on the above research to meet the increasingly strict requirements of clean fuel production.Firstly,starting with the traditional alumina-based catalysts,a series of Co Mo/Al₂O₃ catalysts were prepared by impregnation method.The effects of active component loading amount and impregnation sequence of the catalysts were investigated via the analysis of XRD,BET,NH₃-TPD,Py-IR,Raman,UV-Vis and HRTEM.The results show that the loading amount of active components is Co O5%and Mo O₃15%,and the dispersion effect of active components of the catalyst prepared by Co Mo impregnation presents the best.The catalyst has the best desulfurization activity.Pseudo boehmite was calcined at different temperatures to form alumina carriers with various crystal forms.Among them,the catalyst prepared withγ-Al₂O₃ calcined at500℃as the carrier has the best hydrodesulfurization effect.Compared with conventional calcination,microwave calcination changes the acid properties of the catalyst,increases the amount of B acid and significantly promotes the hydrodesulfurization activity of the catalyst.The desulfurization rate of DBT model compound can be increased to 98.03%at 200℃by 7.69%.Secondly,Y zeolite was used to modify Co Mo/Al₂O₃ catalyst.The effects of the addition amount of Y zeolite,types and molecular sieve ion exchange conditions on the performance of the catalyst were investigated.The results show that the introduction of Y zeolite increases the specific surface area of the catalyst and improves the dispersion of active components;On the other hand,B acid content of the catalyst is enhanced,the interaction between the active components and the support is obviously weakened,and more Co Mo S active phases are formed,so as to improve the catalytic performance of the catalyst.The desulfurization rate of FCC gasoline by the modified catalyst can reach more than 95%.Finally,the effect of citric acid modification on Co Mo catalyst and the enhancement of microwave radiation on hydrodesulfurization reaction process were studied.The effects of citric amount and introduction method on the catalyst activity were tested.The results show that the dispersion of active components is enhanced with the introduction of citric acid,the interaction between active metal and support is weekened,the vulcanization of Mo material is promoted and more Co Mo S（II）active phase is formed,so as to improve the hydrodesulfurization activity of the catalyst.In compariation with conventional heating methods,the desulfurization rate of FCC gasoline is increased 2%-3%in microwave enhanced hydrodesulfurization reaction.Microwave enhanced hydrodesulfurization is more effective at low temperature.