Preparation Of Nanoscale α-FeOOH And Its Catalytic Performance In Coal-Oil Co-refining

China is a large energy-demanding country with rich coal and less oil.It is highly efficient in processing low-quality heavy oil（natural heavy crude oil or asphalt,atmospheric vacuum residue and various secondary processing residues）to obtain high quality light oil products.Coal/oil co-refining technology is one of the major advances in the field of direct coal liquefaction research.At the same time,it solves two major problems of clean and efficient coal conversion and inferior heavy oil deep processing.The advantages of coal/oil co-refining technology are mainly reflected in the synergy between coal and heavy oil,high conversion rate of raw materials,high production efficiency,high product quality and low production cost.The catalytic activity of the catalyst is one of the key technologies affecting the coal/oil co-refining process.This thesis mainly investigates the preparation of nano-sized iron oxyhydroxide and discusses the catalytic activity in the application of coal/oil co-refining system.The effects of different precipitants on the crystal size of the catalyst and the improvement of the dispersion of the dispersed phase and surfactant were studied.The nano-sizedα-FeOOH crystals were prepared by air oxidation precipitation method and characterized.Firstly,FeSO₄·7H₂O was used as the iron source and ammonia was used as the precipitant.The catalyst was characterized by XRD,FT-IR and SEM.The crystals were pure phase nano-scaleα-FeOOH crystals with diameters of 60 nm¹00 nm and lengths of 400 nm⁶50 nm,and the shape is relatively regular,and the degree of mutual adhesion is not serious.Secondly,after the process conditions for preparing the catalyst are determined,the dispersed phase is changed,and ethanol is used as a dispersed phase,and a dispersing agent（cetyltrimethylammonium bromide,sodium dodecylbenzenesulfonate,polyethylene glycol 300,Alpha-FeOOH crystals were prepared from polyvinyl alcohol and polyvinylpyrrolidone K30）.The preparedα-FeOOH samples were characterized by XRD and FT-IR characterization.The catalysts wereα-FeOOH and the crystal lattice was complete and the purity was high.SEM and TEM characterization showed that the structure of the catalyst was obvious,the particles were loose,the diameter was30⁸0 nm,the length was 300⁶50 nm,the adhesion was decreased,and the dispersibility was improved.The BET characterization analysis showed that the specific surface area of the catalyst was greatly improved,and the pore size decreased slightly.With the addition of polyvinyl alcohol dispersant,the specific surface area increased from 29.88 m²/g to 71.03 m²/g,with an increase of 137.7%,and the average pore diameter was from 71.03 nm.Dropped to 20.08nm.The TG-DTG characterization shows that the weight loss of FeOOH is improved to some extent,and the amorphous structure of the catalyst FeOOH is more stable.The prepared catalyst was applied in the coal/oil co-refining system,and the effects of different kinds of catalysts,oil-to-coal ratio,H2 pressure,catalyst addition amount,reaction time and temperature on the coal/oil co-refining process were investigated.Light oil was prepared by co-refining the Inner Mongolia Erdos lignite and Venezuelan heavy oil by hydrocracking reaction（investigating the conversion rate of lignite and inferior heavy oil,selective cycle yield）to discuss the influencing factors.The optimum process conditions in the laboratory state were determined as the ratio of oil to coal 4:1,hydrogen pressure 16 MPa,catalyst addition amount 3%m（dry coal）,reaction temperature 400-430°C,reaction time 60 min,and the modified catalyst was selected,among which tetrahydrofuran was selected.The catalyst prepared by using ethanol as the dispersed phase and polyvinyl alcohol as the additive is applied in coal/oil co-refining,under the co-refining system.The yield of insolubles decreased from 13.67%to 2.58%,the asphaltene yield decreased from2.78%to 1.1%,and the oil yield increased from 70.77%to 83.54%.Higher than the reported values in the literature:oil yield 65%to 80%.