Structural changes of Shenfu coal in pyrolysis and hydrogasification reactivity of the char

Coal hydrogasification, divided into coal pyrolysis and char hydrogasification, was studied in a fixed bed reactor.FT-IR gas analyzer, Laser Raman analyzer and XRD were applied to analyze the relationship between gas production component of coal pyrolysis and microstructure change of char, and the influence of microstructure change of char on char hydrogasification reactivity.The results show that pyrolysis temperature has an obvious effect on microstructure and hydrogasification reactivity of char.With rising temperature, the ratios of Raman band area A_D1/A_G, A_D2/A_G, A_D3/A_G, A_D4/A_G gradually rises, and the ratio of A_G/A_All decreases within 400-800℃ and increases within 800-900℃.It indicates that graphitization process of char is obviously emerged due to the increase of relative amount of disordered carbon in pyrolysis.The results of XRD analysis are in accordance with those of Raman analysis.The interplanar crystal spacing d₀₀₂ increases within 400-800℃.d₀₀₂ decreases and L₀₀₂ increases sharply within 800-900℃.By fitting the Raman area ratio formula (aA_D1/G+bA_D2/G+cA_D3/G+dA_D4/G) with hydrogasification reactivity (τ_0.5), the obtained factor represents the hydrogasification reactivity of carbon microcrystal.The factor is bigger, and the reactivity of carbon microcrystal is better.