Efficient Direct Brown Coal Liquefaction with Sulfided Co/SiO₂ Catalysts

Direct liquefaction of lower-rank coals and biocoals with magnetically separable catalysts as a sustainable route to fuels

“…A sample of the ''Biocoal'' was obtained from SunCoal and produced out of plant remains. The pretreatment and storage methods of the coals are described elsewhere [19,32]. The results for the higher heating values, the proximate and the ultimate analysis for the three coals are shown in Table 1.…”

“…Additionally, the structure of the low-rank coal should be considered. Therefore a brown coal with a high aliphatic content could be beneficial for lowering the reaction conditions, and this has been shown before [19]. Such ''bitumen-rich'' brown coals can be obtained by selective mining technologies, e.g., from brown coal seams in Central Germany [20], possess H/C molar ratios up to 1.25 and have already been shown to be promising for DCL reactions in our previous works [19,21].…”

“…By introducing a novel nanostructured Co/SiO 2 DCL catalyst, we were able to obtain oil yields up to 55 wt.% out of the premium coal and to do one catalyst recycle without a significant loss in activity [19,21]. Besides Wang et al [22] and Shadle et al [23], there are hardly any publications about the DCL of bitumen-rich coals.…”

“…In the first part of this paper, we deal with the need of a more active DCL catalyst by increasing the metal dispersion of our Co/ SiO 2 catalysts used in previous studies [19,21], by an improved thermal treatment. In addition, we employ a novel magnetic SiO 2 /Fe 3 O 4 support for a better catalyst recovery.…”

“…In order to achieve better results under milder reaction conditions, we lowered the temperature to 623 K and increased the metal dispersion of the nickel catalyst, which is recoverable since our biocoal does not include organic sulfur [34] which normally destroys the magnetic recoverability of Ni/TiO 2 due to sulfidation [19,21].…”