Characteristics of gas evolution profiles during coal pyrolysis and its relation with the variation of functional groups

Abstract

Strict relation between the substituents or functional groups attached to the coal macromolecules and the generation of the volatile products, e.g., CH 4 , H 2 O, CO, CO 2 , etc., during the coal pyrolysis is an important but confusing subject. In this paper, quadrupole mass spectrometry, gas chromatography, and 13 C nuclear magnetic resonance are applied to real-time monitoring the formations of volatile products, off-line quantitative determination of the total products from the pyrolysis of a sub-bituminous coal (SC), and the changes of diverse substitents in the SC along with coke foamation, respectively. These measurements are also performed for the pyrolysis of a caking coal to contrast SC. The qualitative and quantitative data reveal that, during coal pyrolysis, the functional groups related with the formation of CO, i.e., ether, carbonyl, and anhydride, can directly generate CO via bond breaking, or take a detour of the formation of other intermediates via condensation and recombination firstly. Moreover, the formations of CO 2 and CH 4 are related to the direct removal of -COO-and -CH 3 , respectively.

Gas Generation and Its Carbon Isotopic Composition during Pyrite-Catalyzed Pyrolysis of Shale with Different Maturities

“…Various gases were detected during the Geniai shale pyrolysis, including CH 4 , C 2 -C 5 , H 2 , CO and CO 2 . The thermogenic alkanes, such as C 1 -C 5 , originate mainly from the cleavage and polymerization of C−C chains attached to aromatic rings and aliphatic structures [52]. The likely sources of CO 2 mainly include the cracking and reformation of the ether, carbonyl and carboxyl groups from kerogen [24,50,53].…”

Influence of coal treatments on the Ni loading mechanism of Ni-loaded lignite char catalysts

“…The XRD patterns of Ni metal in Ni-loaded lignite char catalysts in this study also correspond to the report by Chaiklangmuang et al 18 The occurrences of Ni metals on all catalysts could be explained by the fact that the Ni ions (Ni 2+ ) that were exchanged with the oxygen-containing functional groups (e.g., hydroxyl, carboxyl and metal-carboxylate groups) in the untreated coal and each treated coal were reduced by H 2 and CO and turned into Ni metal (Ni 0 ). 49,50 The H 2 and CO were generated by the decomposition of the aliphatic hydrocarbons, hydroxyl and carboxylate groups of Ni-loaded coal samples during pyrolysis at 650 C. 51,52 The decomposition of the aliphatic hydrocarbons, hydroxyl and carboxylate groups of Ni-loaded lignite coal samples were conrmed by the FTIR spectra of catalysts. In Fig.…”

Experimental Study on Influencing Factors and Thermal Effects of CO2 Adsorption by Coal

“…There are also large pores that facilitate gas diffusion. Zhang et al 14 studied the deformation characteristics caused by CO 2 adsorption on coal under isothermal conditions and established an isothermal adsorption-deformation model. He et al 15 used an isothermal adsorption device and a D - R model to analyze the relationship between the coal volumetric strain and adsorption capacity and studied the influence of coal rank and pressure on CO 2 adsorption capacity.…”