Study On Preparation Of Multi-Stage Porous Carbon Materials From Coal/Heavy Oil Hydrogenation Co-Refining Residue

The co-refining technology of coal/heavy oil is a clean coal conversion technology.The residue yield of>500℃in the product is high and the properties are poor.Especially,the metal compounds are high and difficult to use.Therefore,this paper attempts to develop a way to use the residue with high added value.In this paper,the multi-stage porous carbon material was prepared by direct chemical activation method with COVR as raw material;The multi-stage porous carbon was prepared by two steps of pre carbonization chemical activation with the separation of COVR-TI from the residue as raw material;The adsorption and electrochemical energy storage performance of the multi-stage porous carbon were investigated.The results show that the optimum conditions for the preparation of multi-stage porous carbon materials from COVR are as follows:the mass ratio of KOH to raw material is 2:1,activation temperature is 900℃,activation time is 1 h.under this condition,the specific surface area of multi-stage porous carbon material is 2054.32 m²·g^-1,total pore volume is 1.1283 cm³·g^-1,microporous ratio of 0.5-2 nm is 22%,and mesoporous ratio is 78%at 2-5nm.The optimum conditions for the preparation of multi-stage pores from COVR-TI are as follows:the mass ratio of KOH to raw material is 1:1,activation temperature is 800℃,activation time is 1 h,the specific surface area is 1126.76 m²·g^-1,the total pore volume is 0.5714 cm³·g^-1,the microporous ratio of pore size is 63%and mesoporous ratio is 37%at 2-5 nm.Compared with COVR carbon,COVR-TI carbon has high micropore,small pore volume and small specific surface area.The results show that the static saturated adsorption capacity of COVR carbon to toluene is 601.45 mg·g^-1,while that of COVR-TI carbon is 378 mg·g^-1,and is better than 281 mg·g^-1 of commercial activated carbon.The electrochemical energy storage performance of the two kinds of carbon materials as cathode of lithium battery were further investigated.The discharge specific capacitance of COVR carbon material was 61.6 m Ah·g^-1,and the specific capacitance was 55.5 m Ah·g^-1 after 1500 cycles,and the efficiency was over 98%;The specific discharge capacitance of COVR-TI carbon material can reach 45.2 m Ah·g^-1.After 1000 cycles,the specific capacitance is 37.2 m Ah·g^-1,and the efficiency can be kept 98%.The capacitance and stability of both carbon materials are better than commercial Kurary YP-80F active carbon.The results show that the carbon materials with high specific surface area and high total pore volume have strong adsorption capacity.When the carbon materials with high total pore volume and mesoporous pore capacity are used as cathode of lithium battery,they have better electrochemical energy storage performance.Under the optimized conditions,the multi-stage porous carbon materials with better adsorption and electrochemical energy storage performance can be prepared by using the residue of coal/heavy oil co refining.