Design,preparation And Performance Of ZSM-5-Based Catalysts For Heavy Oil Upgrading Under Methane Environment

With the increasing consumption of conventional crude oil resources,the world’s crude oil is becoming heavier and inferior,which poses a great challenge to the existing heavy oil upgrading technology.Currently,hydrocracking has become the most promising process for heavy crude oil processing,but it has a series of problems,such as high cost,safety risk by using hydrogen,etc.,and the catalytic hydrogenation of heavy oil under co-aromatization catalyst can effectively solve the above problems by direct activation of methane without reforming as a hydrogen source instead of hydrogen.Considering the background of the current transformation which upgrading of crude oil from"fuel"to"fuel-chemicals",it is of great significance to upgrading crude oil and produce high value-added chemical products.In this paper,the performance of methane co-aromatization catalysts for crude oil upgrading and light aromatics generation under methane was explored.In this study,the effects of reaction conditions,such as reaction temperature,reaction pressure and mass space velocity,on catalytic performance of upgrading Saudi medium crude oil under methane environment were investigated in a fixed-bed reactor by 1%Ag-10%Zn/HZSM-5.The results show that the optimized reaction conditions are as follows:the reaction temperature is 410℃,the reaction pressure is 5 MPa,and the mass space velocity is1 h^-1.Under these conditions,the viscosity of the product oil dropped from 12.50 mm²·s^-1 to to 5.57 mm²·s^-1,and the yield of the product oil and light aromatics is 87.45%and 9.26%,respectively.Secondly,The results of the catalytic performance of 1%Ag-1%Ga/HZSM-5under the same conditions show that the optimal reaction conditions are as follows:the reaction temperature is 400℃,the reaction pressure is 5 MPa and the mass space velocity is1 h^-1.the viscosity of the product oil decreases to 6.82 mm²·s^-1,the liquid yield is 90.81%,and the light aromatics yield of the product oil is 13.15%.Furthermore,compared with 1%Ag-10%Zn/HZSM-5,1%Ag-1%Ga/HZSM-5 catalyst has better catalytic catalytic performance,and the yield of light aromatics is 3.89%higher at lower temperature.Under the conditions of 400℃with similar oil properties and liquid yield,the yields of resin+asphaltenes and light aromatics were 0.52%lower and 6.87%higher.In addition,the experimental results of model compounds of gasoline and diesel show that the large increase of light aromatics in the product oil may be attributed to that activated methane participate in the co-aromatization of small molecules from the pyrolysis of heavy oil and the feedstock,and the cracking of the diesel oil fraction.Finally,the catalytic performance of hierarchical ZSM-5-based catalysts and catalysts with different Ga loading on upgrading Saudi medium crude oil under methane were also investigated.The results show that compared with the ZSM-5-based catalysts,the oil liquid yield of the hierarchical ZSM-5-based catalysts was increased by 0.45%and the light aromatics yield was increased by 1.44%.In addition,the increase of Ga content is beneficial to the upgrading of Saudi medium crude oil and the generation of light aromatics.When the Ga content is 2%,the acidity of catalysts is suitable and the yield of light aromatics is 16.04%.