Experimental Study On Ultrasonic Assisted Oil Removal Of Spent Catalysts In Petroleum Refining

The aluminum-based petroleum refinery hydrodesulfurization waste catalyst,an important secondary resource for extracting molybdenum,contains rare precious metals such as molybdenum,nickel,and vanadium.And its content is much higher than that of natural minerals.The comprehensive recycling of molybdenum in the spent catalyst can not only alleviate the current lack of rare and precious metal resources,but also help reduce environmental pollution and realize the recycling of resources.In this paper,in view of the deficiency of existing treatment methods for waste hydrodesulfurization catalysts,ultrasonic-assisted ethanol deoiling-microwave roasting-ultrasonic assisted leaching of molybdenum was studied,and the optimum process conditions and pyrolysis kinetics of the deoiling process was analyzed emphatically.Based on this research,the intrinsic mechanism of the ultrasonic-microwave synergistic effect to increase the recovery of molybdenum was obtained.The main research content is as follows:Ultrasound assisted ethanol degreasing process for spent catalysts.On the basis of single-factor condition experiments,the effect of different process parameters on the deoiling rate of spent catalysts was systematically studied by response surface methodology,and the optimum process conditions were determined:ultrasonic temperature 55°C,ultrasonic time 2 h,ultrasonic power 600 W,the ratio of liquid to solid was 5:1.Under this condition,the deoiling rate of the spent catalyst reached99.8%,while the oil removal rate without ultrasonic assistance was only 81.86%.The experimental results are consistent with the model fitting results,which proves the validity of the model.The pyrolysis properties and kinetics of spent catalysts were studied.The pyrolysis curves of different heating rates under air and nitrogen atmosphere were obtained,and the pyrolysis process was analyzed.The results showed that the temperature range of volatile decomposition of waste catalyst oil was 200-450°C,and the main temperature range of metal sulfide oxidation process was 350-600°C.Non-model,model and master curve method were used to fit the kinetic equations of the deoiling stage.The results showed that the degrease reaction kinetics model conformed to the three-dimensional diffusion and chemical reaction model.A method for recovering molybdenum from deoiled catalyst was used microwave oxidation roasting and ultrasonic wave assisted Na₂CO₃ leaching to enhanced rate.The effects of temperature,reaction time and ultrasonic power on the leaching rate of molybdenum were investigated.When the ultrasonic temperature was 65°C,the time was 2 h,and the power was 700 W,the leaching rate of molybdenum in the deoiling catalyst reached 98.18%.But in routine firing for 15 minutes,the leaching rate was only 61.55%under the same conditions,While extending the conventional roasting time to 2h,the leaching rate was 96.02%,which fully proved the microwave efficiency.The samples were analyzed by XRD,XRF,chemical titration,contact angle measurement,GC-MS,SEM,XPS,etc.,focusing on the occurrence of molybdenum,cobalt,and sulfur elements in the spent catalyst before and after deoiling,roasting,and leaching.The content was studied.The results showed that the spent catalyst can effectively avoid the formation of insolubles Co MoO₄ by ultrasonic assisted degreasing and microwave roasting,thus effectively increasing the leaching rate of molybdenum.