Study On Water Gasification Performance Of Mongolian Bituminous Coal Modified By Carbide Slag

In this paper,added carbide slag,a by-product of the polyvinyl chloride（PVC）produced by the"Calcium Carbide Method",into Mongolia Khushuut bituminous coal for steam gasification experiments to achieve the preparation of high-hydrogen synthesis gas.At the same time,XRD,Raman,SEM,TEM,FTIR,XPS and other characterization methods were used to characterize the coal char at the corresponding reaction temperature,and the relationship between the steam gasification performance of bituminous coal catalyzed by carbide slag and the change of coal structure was analyzed.The research results show that the Mongolian bituminous coal sample added with carbide slag has obvious steam gasification catalysis.The presence of carbide slag increases the reaction efficiency of bituminous coal to produce hydrogen and significantly increases the H₂/CO ratio in the synthesis product.The study found that highly dispersed CaO in coal char is the key to catalyzing the steam gasification reaction.Mongolian bituminous coal produces a large number of polycondensation reactions in the temperature range of 700-900℃steam gasification reaction.The polycondensation reaction leads to the ring opening of the hetero-oxygen ring in the coal sample,exposing many phenol ether-based oxygen-containing free radical groups.The phenol ether-based oxygen-containing free radical group and CaO decomposed from carbide slag decomposes at 700-900℃in steam gasification experiments associate with each other to form a CaO-OR structure.The CaO-OR structure realizes that CaO is highly dispersed and amorphous in coal char.Therefore,at the reaction temperature,no crystalline diffraction peak of CaO was found in the bituminous coal char,but the crystalline diffraction peak of CaO was found in the XRD of the gasification residue.It shows that highly dispersed CaO recrystallizes during water gasification.Elements such as Si and Al contained in bituminous coal will prevent the dispersion of CaO,thereby inhibiting the steam gasification experiments activity.Adding carbide slag to Mongolian bituminous coal for 900℃isothermal pyrolysis experiments at different times found that the polycondensation reaction of bituminous coal char will proceed quickly in pyrolysis time between 1-5 hours.The heterooxo ring in the coal sample is opened,and many ether-based oxygen-containing free radical groups are formed.The generated ether-based oxygen-containing free radical groups and the CaO from the carbide slag at 900℃associate with each other to form a CaO-OR structure.The CaO-OR structure realizes that CaO is highly dispersed and amorphous in coal char.The results show that the phenol ether-based oxygen-containing radicals generated by the high-temperature polycondensation reaction of bituminous coal during the steaming process achieve the highly dispersed CaO and a more disordered carbon structure,significantly reduces the activation energy of the reaction and improves the reactivity of steam gasification.