Study On New Catalytic Cracking Catalyst And Process

Light olefins play an important role in the chemical synthesis industry,and the market demand for light olefins increases rapidly.Compared with the steam cracking process,the catalytic cracking process adopts mild operating conditions due to the introduce of catalysts,and high yield of value-added products is achieved.Therefore,it is of great significance to explore suitable catalysts and the optimal catalytic cracking condition that can be used in circulating fluidized beds.In this paper,HZSM-5 was modified with Si O₂,and the effect of Si O₂ on the properties of the catalyst and catalytic cracking performance was studied.The experimental results showed that the Si O₂ did not damage the phase of HZSM-5 zeolite.Si O₂ were dispersed on the external surface of the HZSM-5 zeolite to modify the orifice and the acid property of external surface.Compared with silica sol,tetraethyl orthosilicate was considered as a more suitable silicon source.The optimum deposition amount of Si O₂ was about 5%.Under the condition of 650 ^oC,0.1 MPa,n-butane/nitrogen=2/38 ml/min,the conversion of n-butane reached 98.18%,and20.49%yield of propylene was obtained.This paper studied the catalytic cracking performance of metal oxide catalysts.With the increase of V₂O₅ loading,the conversion rate of n-butane and the yield of ethylene and propylene both showed an increasing trend before reaching a peak at 10%loading of V₂O₅and then presented a decrease trend.Noteworthily,the induction period was found on both x V/Si O₂catalysts with different loadings when n-butane was selected as feedstock.While,the induction period has been successfully eliminated by improving the preparation method of the catalyst.On Al₂O₃,Si O₂,and kaolin supports,with the increase of Zn O loading,the conversion of n-butane and the yield of light olefin both showed an increasing trend firstly and then decreasing trend was found.The optimal loading of Zn O on Al₂O₃,Si O₂,and kaolin supports were 28%,36%,and 5%,respectively,and kaolin was considered as the optimal support for Zn based catalyst among three supports.A new type of catalytic cracking catalyst with dual active components was developed,the optimal loading of active component A and B was 5%and 20%,respectively,and the introduction of active component B was more conducive to produce propylene.In this paper,the catalytic cracking reaction performance of different feedstocks（such as C4,n-pentane,naphtha,paraffin-based crude oil）on a new type catalytic cracking catalyst with dual active components was studied on the ZDT-1 riser catalytic cracking pilot plant.The effect of operating condition on the conversion of n-butane and product distribution was investigated.When the reaction temperature was 700 ^oC and the residence time was 3.17 s,the conversion of n-butane reached 48.83%,and 15.56%ethylene and 17.71%propylene were achieved.The yield of propylene in the cracking reaction products of C4 with different compositions were similar,but the yield of ethylene was affected by the content of n-butane in C4.When the reaction temperature was 700 ^oC and the residence time was 3.60 s,the conversion of n-pentane reached 80.50%,and the total yield of ethylene and propylene was 53.81%.The total content of alkanes and cycloalkanes in Thai naphtha was more than 90%.The order of cracking difficulty for different components was aromatics>cycloalkanes>saturated hydrocarbons.Both Zhongyuan crude oil and Daqing crude oil were paraffin-based crude oils with a high saturated hydrocarbon content.The total yield of ethylene and propylene from Daqing crude oil at 700℃was 52.29%,which was about 2%higher than that of Zhongyuan crude oil.The yield of gasoline in the liquid product was low,and C5 olefins and benzene were considered as the main components.More bicyclic aromatic hydrocarbons were found in diesel product,and the yield of heavy oil is not high.The cracking reaction is relatively thorough.In conclusion,the new catalytic cracking catalyst with two active components has excellent catalytic cracking performance,which can be used for cracking C4,n-pentane,naphtha,paraffin-based crude oil,and other feedstocks.