Recovery And Reclamation Of Spent Fluid Catalytic Cracking Catalyst

Fluid catalytic cracking(FCC)catalysts are the largest usage amount of catalysts in oil refining industry,the consumption of FCC catalysts is about two hundred thousand tons per year in our country,and about one hundred and fifty thousand tons of the spent catalysts can be produced due to the inactivation and particle breakage during the operation.The main treatment method of FCC spent catalysts is burying,the poisonous metal can come out from FCC spent catalysts after rain wash and pollute the groundwater,soil and river.In addition,FCC spent catalysts have small particle sizes which is less than one hundred microns,they have strong tendency of suspension and adsorption which make themeasier to carry and adsorb harmful and poisonous substances and form hazes.It has the mature technology which passed commercial verification to process and recycle one part of the FCC spent catalysts-the equilibrium catalysts discharged from operation unit by artificial way,but there is no commercial confirmed recovery and reclamation utilization technology to process another part of the spent catalysts-TSS powders generated from natural running loss.Based on the composition and structural characteristics of the TSS powders,this paper explores the recovery and reclamation utilization method and technology of the TSS powdersin the synthesis ofY zeolite,the preparation of FCC catalyst matrix and the recovery of metallic elements,etc.The research found that the partial zeolite structure in the TSS powders was not destroyed,it had similar chemical composition with Y zeolite.In this paper,the TSS powders are used to synthesize Y zeolite by in situ crystallization method.Beating the TSS powders and sodium silicate together and making theTSS powders into microspheres by spray drying,and Y zeolite can be prepared from microspheres by in-situ synthesis.The preparation of Y zeolite microspheres with typical structure characteristics of Y zeolite and the crystallinity of 54.8% can be prepared from the dosage of guiding agent,silica-alumina ratio of feed,sodium aluminum ratio of feed,optimization of crystallization temperature and time.The research confirmed the technical feasibility of in-situ synthesis of Y zeolite by using the TSS powders,and FCC catalyst can be preparedafter the ion exchange and hydrothermal ultra-stable method to modify the Y zeolite microspheres.However,the strength,thermal stability and catalytic performance test results were not desirable which had a certain difference with commercial FCC catalyst.The research found that the TSS powders didn't have caking property and poisonous metalswerethe main reason of the inferior catalytic performance.The support of FCC catalyst is amorphous aluminum silicate with appropriate pore structure,surface area and surface acidity,FCC TSS powder contains high heavy metal like Ni,V,Fe,etc.The matrix can be prepared through a series of hydrothermal process methods such as adding silicon,adding alkali,rare earth exchange,H exchange,washing,drying,calcination,ammonia exchange,etc.The research confirmed that the preprocessing of acid had good demetalization performance which had obvious influence on composition and structure of FCC TSS powder,and the removal rate of heavy metals can reach up 80%.It is also confirmed that the appropriate matrix of FCC catalystcanbe made fromTSS powder as raw materials,which thematrix owned the structural characteristics of Y zeolite,high surface area,micro-and mesopore volumes.It had wide pore size distribution interval and mesoporous distribution.Comparing the physical and chemical properties of FCC catalyst prepared by the new matrix,the FCC catalyst had a better strength,specific surface,pore structure and micro activity when the new matrix adding amount is6%.The evaluation result of FFB showed that the new matrix can increased heavy oil conversion rate,decreased coke yield,and increased the catalyst catalytic activity and liquid yield.For the purpose of further recycling of the metallic elements in acid liquor generated in preprocessing of TSS powder,the concentration,cooling crystal separation,double salt precipitation separation and alkali sinking methods were used to explore the separation and recoveryof rare earths,aluminium,nickel,iron and vanadium.The obtained precipites and filtrates were tested by XRD,XRF,ICP analyticalmethods.The research showed that the above technical methods can separate and recycle the rare earth,aluminium,nickel,iron and vanadium in the form of rare earth sulfate double salt,aluminum ammonium sulfate,ammonium nickel sulfate,iron,and vanadium oxide in sequence.The recovery rate of metal ions can reach above 98% by the optimized separation conditions.On the basis of above researches,TSS powder was used as raw material to prepare matrix and produce 30 tons of commercial batch of FCC reclamated catalyst which successfully applied on the Refinery of Zhongyuan Oilfield Company SINOPEC with the capacity of 500000 tons.The commercial test showed that,during the trial period of the reclamated catalyst,the FCC unit operating steady,catalyst fluidized regularly in reactor and regenerator,catalyst running loss didn't appear,the activity,stability and selectivity of catalyst didn't have obvious change,and the product distribution and product properties were the same asthe previous commercial catalyst.The initial success of commercial application showed the feasibility of TSS powder recycling catalyst technology which had the potential of large-scale application.In conclusion,the research result makes a complete technical approach which contains TSS powder synthesizing Y zeolite,preparation of FCC catalyst matrix and recycling of metallic elements.It establishes the technical foundation for recovery and reclamation utilization FCCU spent catalysts.