Correlation between pores and chemical structures in CO₂ gasification char of Naomaohu coal

Understanding the relationship between pores and the chemical structures of char can help analyze the interaction between chemical reactions and mass transfer during coal gasification. In this paper, chars prepared from Naomaohu coal by a drop tube furnace and a fixed bed reactor at 700 ℃, respectively, were gasified in CO₂ by the drop tube furnace at 900 ∼ 1000 ℃ to obtain gasified char samples with different pores and chemical structures. The structure characterization results of this gasified char samples indicate that the mesopore-specific surface area increases exponentially from 146.8 to 409.3 m²/g with the decrease of A_G/A_Other (the ratio of the peak G area to the sum of other peaks except for peak G and peak D in the Raman spectrum) from 0.68 to 0.45, and thus an exponential correlation was proposed to predict this trend. The specific surface area of the pores 0.44–0.60 nm increases with increasing aliphatic carbon content and the specific surface area is 110.5 and 260.2 m²/g when the aliphatic carbon content is 0.07 and 0.17, respectively, while the specific surface area of the pores of 0.72–0.98 nm increases with increasing substituent content (including aliphatic carbon and carbon bonded with oxygen atoms), and the specific surface area is 28.3 and 51.6 m²/g when the substituent content is 0.17 and 0.43, respectively.