Ligand Optimization And Catalytic Performance Research Of The Catalyst In Heavy Feedstock Slurry Bed Hydrogenation

The oil-soluble catalyst used in the slurry-bed hydrocracking of heavy raw materials has the advantages of good dissolution and dispersion performance and high activity of hydrogenation and coke suppression.However,this type of catalyst has a single source of organic ligands and high production costs,which hinder its industrial production and application.Therefore,it is necessary to further expand the selection range of this type of catalyst ligand and reduce its synthesis cost.In this paper,aiming at the problems of the oil-soluble catalyst for the slurry-bed hydrocracking reaction of heavy raw materials（coal/heavy oil,petroleum residue）,the ligand was optimized and the preparation process was optimized,and the oil-soluble iron-nickel bimetallic catalyst and oil-soluble molybdenum catalyst was prepared.FT-IR,XRD,TG and other characterization methods are used to analyze the decomposition temperature difference and structure difference of the catalyst precursor;using SEM,XPS,DLS and other characterization methods to investigate the microscopic morphology and structure characteristics of the sulfurized products of oil-soluble catalysts;furthermore,the reactivity of the synthesized oil-soluble iron-nickel catalyst and oil-soluble molybdenum catalyst in the coal/heavy oil slurry-bed hydrogenation co-refining system and petroleum residue slurry-bed hydrogenation system was investigated.Elemental analysis,FT-IR,¹H-NMR and other characterization methods were used to investigate the composition and structure of liquid product and solid residue.Studies have shown that,within the scope of the experimental investigation,the maximum thermal weight loss temperature of the synthesized oil-soluble iron-nickel catalyst is in the range of 320～340℃.With the increase of the carbon chain length in the oil-soluble ligand,chelated COO^-groups appeared in the catalyst,which made the catalyst precursor more stable and the decomposition temperature increased slightly.At the same time,by comparing the particle size and morphology of the vulcanized product,it can be seen that with the increase of the carbon chain length of the ligand,the vulcanized product shows a trend of gradually decreasing particle size and increasing degree of dispersion.Coal/heavy oil hydrogenation co-refining results show that with the increase of the carbon chain length of the oil-soluble catalyst ligand,the effect of its hydrogenation and coke suppression is gradually obvious.Among them,the oil-soluble iron-nickel catalyst synthesized by using fatty acid D（C16）as a ligand source can achieve 61 wt%oil yield after the actual reaction,the conversion rate of dry-based ash-free coal over 96%.After the synthesis method of oil-soluble molybdenum catalyst was improved,the recovery rate of active metal of the catalyst and the content of active metal in the product were improved,the recovery rate of active metal exceeded 85%,and the content of active metal in the catalyst increased from 3 wt%to about 10 wt%.At the same time,in the vulcanization process,the oil-soluble molybdenum catalyst synthesized by using fatty acid F as an organic ligand has a higher degree of dispersion and a more uniform particle size distribution,with an average particle size of 280.4 nm.This shows that fatty acid F is a better choice to replace certain organic acids as the source of organic ligands for oil-soluble molybdenum catalysts.Residual oil hydrogenation experiment results show that the oil-soluble molybdenum catalyst synthesized with fatty acid F as the ligand exhibits excellent hydrogenation activity.When the catalyst addition amount is 150μg·g^-1（based on the active metal content）,the light oil yield of can reach 40.16 wt%,and the coke rate is only 1.58 wt%.