Investigation Of The Interaction Of Coal And Catalyst During Pyrolysis And Steam Gasification

China's energy structure is more coal,less oil and less gas.The use of abundant coal resources to produce substitute natural gas can not only alleviate the contradiction between the supply and demand of natural gas,but also promote the efficient and clean use of coal.Coal conversion mainly occurs in the process of pyrolysis and gasification reaction,can obtain methane,hydrogen and other gas products,they can also obtain tar.Alkali metal catalysts can combine with macromolecules in coal to improve the carbon conversion rate.Although a large number of studies have been conducted on the interaction process between catalysts and coal,The role of catalysts in the chemical bond cleavage in coal and the synergistic effect of multi-component catalysts on coal pyrolysis and gasification processes need to be further explored.Based on the preliminary work of the laboratory,this paper uses K₂CO₃ and KCl as catalysts to explore the interaction between catalyst and coal in pyrolysis and gasification,and obtain the following main results:?1?K₂CO₃ can improve the gas yield and carbon conversion rate of coal pyrolysis at different temperatures.As the pyrolysis temperature increases,the char analysis of infrared and surface elements shows that CO,C=O,COO-relative content is reduced,which may be caused by the formation of the COK intermediate structure after loading the catalyst,and promote the breaking bond conversion of the oxygen-containing group.?2?Compared with the unsupported catalyst Fugu coal pyrolysis,the tar yield and carbon conversion rate are lower,which may be due to the fact that KCl can promote macromolecular polycondensation and has limited conversion to oxygen-containing functional groups.The KCl moiety was used instead of K₂CO₃ to form a two-component system.It was found that when K₂CO₃/?K₂CO₃+KCl?was greater than 0.376,the yield of each product of pyrolysis was close.The low eutectic double-component pyrolysis of the two components showed that the gas yield was slightly lower than that of the supported K₂CO₃ pyrolysis.The change of CO₂ in the gas was large,probably because carbonate promoted the formation of COO-.?3?After gasification,residual semi-coke was analyzed by infrared and XPS.It was found that when the carbon conversion rate was the highest,the relative contents of C-O,C=O and COO-in char were relatively high.It may be that the catalyst promoted the combination of O and C in char to form COK and COOK intermediates.