Kinetic study of CO ₂ gasification on coal char and extraction residue char from direct coal liquefaction

Abstract

Summary Extraction residue (ER) is, in this study, considered as an insoluble portion derived from a novel extraction process with direct coal liquefaction residue, which is the byproduct from 1000 kton/y direct coal liquefaction and oil production process in Ordos, China. ER mostly consists of unreacted coal and minerals, spent catalyst, and solvent. It is considered as a hazardous waste in China. Gasification is a promising way to employ ER, as the carbon resource contained in it could be adequately utilized, so strongly reducing the environmental impact of this material. In this paper, a kinetic study is carried out concerning CO2 gasification (in thermobalance) of ER char, coal char, and their blends. The results show that, at temperatures ranging from 1123 to 1323 K, the reactivity of ER char is much larger than that of coal char, and the reactivity of ER/coal char blends increases when the ER fraction increases, consistently resulting in between the reactivities shown by ER char and coal char alone. The partial pressure of CO2 promotes the reactivity of all samples. BET surface area resulted three times larger for ER char vs coal char, while pore surface area and pore volume were four times larger. Moreover, the relevant parameters of the random pore model for CO2 gasification of ER char, coal char, and their blend #2 (with 20% ER) were obtained; the activation energy resulted 210.6, 240.5, and 232.8 kJ/mol, and the reaction order 0.30, 0.45, and 0.40, respectively.

Structural changes of Zhundong coal matrix induced by thermal treatment and its effects on oil yield in direct coal liquefaction

“…For instance, BET surface areas of T‐300 and M‐300 are 5.87 and 7.86 m 2 /g, respectively. On the one hand, the increase of BET surface area results from the extraction of low‐molecule weight materials 29 . On the other hand, solvents can interrupt the interactions among different coal clusters, which reduces the coalescence possibility of neighboring pores 30 .…”

“…On the one hand, the increase of BET surface area results from the extraction of lowmolecule weight materials. 29 On the other hand, solvents can interrupt the interactions among different coal clusters, which reduces the coalescence possibility of neighboring pores. 30 At 250 C, the surface areas of residues are smaller than those obtained at 200 C (4.24 vs 5.85 m 2 /g, 6.86 vs 7.55 m 2 /g).…”

Experimental Study on Electrochemical Desulfurization of Coal Liquefaction Residue

“…It has the characteristics of high carbon residue, high ash and high sulfur [ 2 , 3 ]. It has been separated by vacuum distillation, accounting for about 20~30 wt.% of the total liquefied raw coal [ 4 , 5 ]. At present, the production enterprises sell and dispose of it as a general solid waste and the resource utilization rate and economy are low.…”

CO2 gasification kinetics of Shenhua bituminous coal by isothermal thermogravimetric analysis

“…[24][25][26] In fact, gasification kinetics at isothermal condition matches actual coal gasification technology, and therefore, the obtained kinetic parameters are more accurate. So far, a large amount of literature [27][28][29][30][31][32] about coal CO 2 gasification has been published. In the work of An et al, [31] the isothermal gasification of extraction residue char from direct coal liquefaction (ER char) with CO 2 has been investigated at temperatures ranging from 1123-1323 K under ordinary pressure.…”

“…So far, a large amount of literature [27][28][29][30][31][32] about coal CO 2 gasification has been published. In the work of An et al, [31] the isothermal gasification of extraction residue char from direct coal liquefaction (ER char) with CO 2 has been investigated at temperatures ranging from 1123-1323 K under ordinary pressure. Tomaszewicz et al [33] used four kinetic models (volumetric model, grain model, modified volumetric model, and random pore model) to investigate the effect of coal rank on the char gasification kinetics.…”