A Comparison of the Gas‐Product‐Release Characteristics from Coal Pyrolysis and Hydrogasification

Abstract

Coal pyrolysis and hydrogasification were investigated in a laboratory‐scale pressurized fixed‐bed reactor to examine the effects of temperature, pressure, and catalyst on the gas productivity and yields under different gas atmospheres. The experimental results show that the methane yield is significantly higher under a hydrogen atmosphere. The release rate curve of methane during hydrogasification has three obvious peaks which are the results of coal devolatilization and rapid hydrogenation, the secondary reaction of volatile products, and the slow hydrogenation of residual char, respectively, whereas that of pyrolysis only exhibits the first peak. Changes in temperature and pressure have more remarkable effects on coal hydrogasification than on pyrolysis. Nickel and calcium‐based catalysts influence the rate of CO and CO2 formation but little effect was observed on low‐carbon hydrocarbon production. Potassium‐ and sodium‐based catalysts have a significant effect on the formation of methane under a hydrogen atmosphere. The FTIR spectra show that hydrogen is easily bound to carbon if of potassium‐ and sodium‐based catalysts are used, and CC bond formation is inhibited, which reduces the aggregation of graphite which has very poor activity. Therefore, potassium‐ and sodium‐catalyzed samples could maintain high activities during hydrogasification.

Dynamic Evolution and Covariant Response Mechanism of Volatile Organic Compounds and Residual Functional Groups during the Online Pyrolysis of Coal and Biomass Fuels

“…Thus, the depolymerization/defragmenting of the H-bonding network exhibited priority responses via temperature-induced weakening/cleavage and dihydroxylation/dehydrogenation/demethylenation reactions. 76,77 This result was consistent with the high sensitivity of hydroxyl/ hydrocarbon groups in biomass-derived char to temperature changes. 31,32 As temperature increased, the subsequent reactions of residual fragments could result in more condensed structures, such as ether oxygen bonds and conjugated ketones.…”

“…These complicated temperature responses for SBC-RFGs reflected more variability in structure, configuration, and composition caused by oxidation reactions. 77 Synergistic Evolved Relationships between VOCs and RFGs. Along with VOC-FTIR and RFG-FTIR, hetero 2D-COS provided novel insights into the synergistic evolution and correlations of gas−solid products during CBF pyrolysis.…”

Technical Progress and the Prospect of Low‐Rank Coal Pyrolysis in China

“…On the other hand, as a result of strong acids and alkalis, the problem of solving the complex compositions of waste water from mid–low‐temperature pyrolysis is extremely difficult. An increase in the scale of pyrolysis production will definitely increase water consumption in a watershed . Therefore, strategies to address the aforementioned factors should be developed.…”

“…An increase in the scale of pyrolysis production will definitely increase water consumption in aw atershed. [42,[54][55][56] Therefore, strategies to address the aforementionedf actorss hould be developed. Va rious mitigation strategies can be employed to minimize the productiono fw astewater, including the requirement of infrastructure constructions to solve the problems of the pretreatment of ammonia nitrogen, separationo fc oke tar, and phenolr emoval.…”

Effect of Biomass Char Additives on the Hydrogasification Behavior of a Bituminous Coal

“…To improve the hydrogasification reactivity of coal, researchers have performed several research studies. Hong et al (2013) used potassium-and sodium-based catalysts and found a significant effect on the formation of methane under a hydrogen atmosphere. Murakami et al (2000) studied Ni catalytic hydrogasification of coal and found that nickel species had a good catalytic effect on the hydrogasification reactivity of brown coal.…”