Study on CO2 gasification mechanism of bituminous coal coke by in-situ measurement and DFT calculation

Abstract

CO₂ gasification with coal/coke is an important technology that can convert and store CO₂ into chemical products in a massive and feasible way. Understanding the mechanism of the CO₂-coke gasification is the basis for the industrialization and designation of CO₂ gasifier, which provide fundamental technology for Carbon Capture, Utilization and Storage (CCUS). In this work, the CO₂ gasification process was studied by Thermogravimetric-Fourier Transform Infrared Spectrometer Mass Spectrometer (TG-FTIR), Thermogravimetric-Mass Spectrometer (TG-MS) and in-situ Raman. The atomic level mechanism of CO₂ reaction with coke was analyzed by Density Functional Theory (DFT) calculation. The result shows that the COO-group in the coke is the CO precursor from the CO₂-coke gasification. In the process of pre-adsorption of CO₂ on the surface of coal coke, the CO-O- group is formed, and the degree of the electron conjugation of the aromatic ring pi is decreased, and the strength of intermolecular mayer bond is decreased, destroying the aromaticity of the coal coke molecular surface, exposing more active sites, accelerating the gasification reaction of coal coke, and promoting CO desorption. And the entire gasification process is the endothermic reaction with 1.60 eV.