Elucidation of coal liquefaction mechanisms using a tritium tracer method: hydrogen exchange reaction of solvents with tritiated molecular hydrogen in the presence and absence of H2S

Recent Advances in Direct Coal Liquefaction

“…The results indicated that there were synergistic effects between coal and methane at temperatures higher than 600 °C, the oil yields reached a maximum of 22 wt% (daf) at 750 °C in the rapid liquefaction for 9.0 s. The effectiveness of CH 4 in coal liquefaction was improved further by co-presence of hydrogen according to the study by Yang et al [35], where the coal conversion attained as high as 51.5% in a gas mixture of CH 4 -H 2 , compared with only 27% under CH 4 atmosphere alone. As discussed before, a sulfided metallic catalyst and a hydrogen donor solvent are two essentials for a DCL process, while the presence of H 2 S in the gas phase could promote the hydrogen exchange and the donor ability of some solvents [36].…”

Effects of sulfur additive on the transformation behaviors of γ‐Fe2O3 and coal liquefaction performances under mild conditions

“…On one hand, H 2 S reacted with iron oxide to form pyrrhotite . On the other hand, H 2 S decomposed to produce active hydrogen that further combined with the free radicals generated from coal pyrolysis . The higher partial pressure of H 2 S could be one of the reasons for higher coal conversion and oil yield.…”

Direct liquefaction techniques on lignite coal: A review

“…Thus, cross-linking/repolymerization reactions are considerably more important at high temperatures for low-ranking coal, such as lignite, than for bituminous coals [53]. Nevertheless, to obtain useful fuels or low-molecular-weight chemicals from low-ranking coals in reduction reactions, high reducing gas pressures and active catalysts to stabilize small fragments have been found to be indispensable [54][55][56]. Suitable sufficiently cheap catalysts are mainly iron-based (hydroxide, sulfate, pyrite), although other metals and their oxides, halides, or sulfides have been used [57].…”

“…Therefore, the hydrogen donor capability of some solvents is promoted easily due to the existence of hydrogen sulfide in the gas phase [71]. Table 3 illustrates the capacities of all the well-known technologies [36,55,62,69], including the five listed above (CT-5 is the same as FFI). Table 3 further suggests that iron-based catalysts can provide the preferred route to achieving high liquefaction yields.…”

“…The other processes that have not been commercialized to date can be described briefly. Solvent refined coal processes (SRC-I and SRC-II) have been developed based on the Bergius process and Pott-Bioche solvent dissolving process (see Table 3) [36,55,62,69]. The IGOR process was carried out in a fixed bed reactor in the presence of red-mud over Ni-Mo/Al2O3.…”