Study on supercritical water gasification reaction and kinetic of coal model compounds

Abstract

Supercritical water gasification (SCWG) of coal is a clean coal utilization technology that has gradually developed in recent years. It has great application prospect because of low pollution, good economy and high energy efficiency. Due to the complexity of coal molecular structure, it is difficult to directly study SCWG mechanism of coal at molecular level. Based on the Wiser molecular structure model of coal, diphenyl ether and diphenylmethane were selected as model compounds to study the bond breaking characteristics and gasification law of characteristic bridge bonds. The effects of catalyst, temperature, concentration and other factors on model compounds gasification were discussed. The results showed that temperature had the most significant influence on gasification effect. The effect order of catalyst on promoting gasification from high to low was: K2CO3 > Na2CO3 > Ca(OH)2. The increase of catalyst amount and residence time had a certain promotion effect on gasification reaction. Under the same condition, the gasification effect of diphenyl ether was better than that of diphenylmethane. At the same time, the kinetic model of coal-like structure model compound gasification in SCW was established, and the key parameters were solved. The activation energy of diphenyl ether and diphenylmethane was 82.96 kJ/mol and 99.92 kJ/mol, respectively.