Preparation And Properties Of Gradient Porous Ceramics From Catalyst Residues

Catalyst slag is an industrial waste produced during petroleum refining and processing.With the continuous development of the national economy,the demand for petroleum processing products has increased year by year,resulting in a large amount of catalyst slag stockpiled,which not only occupies land,but also pollutes the environment.In recent years,as the country pays more and more attention to environmental protection,a series of related environmental protection laws have been promulgated,and the requirements for the treatment of industrial waste have become more and more strict.The legal and effective disposal of catalyst slag has once again attracted extensive attention of researchers.In this paper,the catalyst slag after pressure filtration provided by Qilu Branch was used as the research object,and the gradient pore porous ceramics were prepared by dry pressing and solid-state sintering in cooperation with siliceous materials.Through the influence of molding pressure,particle size of siliceous material and the ratio of slag to siliceous material on the properties of porous ceramics prepared from catalyst slag,the preparation process and technical parameters of porous ceramics were determined.Gradient pore porous ceramics were prepared by press molding.Using TG-DSC,XRD,laser particle size tester and chemical analysis and other testing methods,the structure of porous ceramics and gradient pore porous ceramics was explored.The results show that the porous ceramics and gradient porous ceramics can meet the performance requirements of porous ceramics under the proper preparation process of catalyst slag and silicon materials.The sintering temperature should be controlled below 1200℃,the holding time is 90min,and the forming pressure is 10MPa.When the particle size of silicon material is between 40 mesh and 200 mesh,the compressive strength of porous ceramics increases with the decrease of particle size,and the significant porosity increases.However,when the siliceous material is less than 200 mesh,the compressive strength decreases and the apparent porosity continues to increase.Under different particle sizes of silica materials,the optimum ratio of slag to silica material exists,and the porous ceramics have the best properties.When the particle size of silica material is less than 100 mesh,sintering temperature is 1150℃,holding time is 90min,forming pressure is 10MPa,slag:silica material=1:3,the compressive strength of porous ceramics is 15.44MPa,the apparent porosity is 44.33%.When the particle size of silica material is 100-200 mesh,sintering temperature is 1150℃,holding time is 90min,forming pressure is 10MPa,slag:silica material=1:2.5,the compressive strength of porous ceramics prepared is 17.14MPa,the apparent porosity is 38.4%.When the particle size of silica material is less than 200 mesh,sintering temperature is 1150℃,holding time is 90min,forming pressure is 10MPa,slag:silica material=1:2.5,the compressive strength of porous ceramics is16.86mpa,the apparent porosity is 44.30%.When preparing gradient porous ceramics,the particle size and ratio of three layers of silica material are below 100 mesh,and the silica material is slag=3:2.100-200 mesh,silica material:slag=2.5:1;Up to 200 mesh,silicon material:It is found that the thickness of three layers has an effect on the properties of gradient porous ceramics.When the thickness ratio is1:1:1,the total porosity and mechanical strength of gradient porous ceramics reach the optimal value,and the total apparent porosity is 42%,among which the porosity of the first layer（siliceous material with particle size less than 100 mesh）is 28%.The porosity of the middle layer（silicic material diameter of 100 mesh to 200 mesh）is 41%,and that of the third layer（less than 200 mesh）is 53%,with a compressive strength of 12.5MPa.XRD analysis of porous ceramics and gradient porous ceramics prepared by catalyst shows that the main crystal phases are Si O₂ and Na[Al Si₃O₈].Changing the particle size of silicon materials and slag:the ratio of silicon materials has no significant effect on porous ceramics and gradient porous ceramics.SEM morphology analysis results show that the surface of porous ceramics has uniform distribution,similar pore size and good connectivity.Hole for gradient porous ceramics interface does not exist between the interface crack,the interface between the aperture size is not the same,with the mercury injection experiment data verification test bore gradient ceramics is ladder model developed by gradient porous ceramics,gradient pore structure of porous ceramics is complete,a connection between layer and layer,each layer between the porosity gradient distribution.