Conversion of biomass resources to fuels and chemicals is a highly effective approach for a biomass valorization as a prospective alternative to petrochemical processes. Biomass conversion using water as a reaction medium is desirable because water is non-toxic and environmentally friendly. Biomass valorization techniques in high-temperature liquid water and supercritical water are reviewed, such as (i) dehydration reactions of biomass-derived polyalcohols to cyclic ethers and (ii) gasification reactions of lignin to fuel gases. (i) Cyclic ethers were produced by the intramolecular dehydration reactions of biomass-derived polyalcohols in high-temperature liquid water without acid catalysts. Addition of carbon dioxide accelerated the dehydration in high-temperature liquid water because the added carbon dioxide dissolves in water to form carbonic acid. (ii) Charcoal-supported ruthenium salts were active for lignin gasification at 673 K in supercritical water, in which ruthenium (III) species were reduced to ruthenium metal particles.
Effective energy production from lignocellulosic biomass is one of the most important research topics to employing biomass as a widely used energy source. Using hydrothermal pretreatment, ethanol can be effectively produced from the lignocellulosic biomass. However, the effects of using different feedstock species on ethanol production have not yet been elucidated. In this study, eucalyptus and oil palm empty fruit bunch were selected for hydrothermal pretreatment, followed by enzymatic hydrolysis and ethanol fermentation in order to compare their reaction characteristics. The effect of hydrothermal pretreatment temperature was studied. Furfural, acetic acid, formic acid, and vanillin were studied in the context of being fermentation inhibitors. Differences in glucose production were observed when different feedstocks were used in the hydrothermal pretreatment step, whereas both inhibitor production and its effect on fermentation were the same regardless of feedstock.
Several unsupported and supported molybdenum-based catalysts were prepared by precipitation and impregnation, and characterized by N2 adsorption, XRD, H2-TPR, and XPS. The catalytic activity for alcohol synthesis was evaluated using a fixed-bed pressurized flow reaction system under the following conditions: 250-350 °C, 5.0 MPa, GHSV of 5000 h−1, and H2/CO ratio of 1.0. Addition of Co to the unsupported MoS2-bulk catalyst enhanced the selectivity for C2+ alcohols and total alcohols, and reduced the selectivity for hydrocarbons. Addition of K to Co04MoS improved the selectivity for total alcohols and suppressed the formation of hydrocarbons, increased the selectivity for methanol and CO2, and decreased carbon-chain growth. The alumina-supported catalyst was the most favorable for Fischer-Tropsch synthesis but was unfavorable for C2+ alcohol synthesis. The silica-supported catalyst was more favorable for C2+ alcohol synthesis than the unsupported catalyst.
The gallosilicate type CDS-1 zeolite ([Ga]CDS-1) with CDO topology is prepared from the precursor of gallium-containing layered material ([Ga]PLS-1) by calcination via dehydrative condensation, and the corresponding [Ga]PLS-1 can be successfully synthesized from the mixture of protonated kanemite (H-kanemite), Ga2O3, tetramethylammonium hydroxide (TMAOH) as structure-directing agent (SDA), NaOH and H2O. These materials have been characterized by powder XRD, TG-DTA, FE-SEM, nitrogen adsorption and solid state NMR, and their solid acid properties were evaluated by NH3-TPD analysis after protonation. The obtained proton type [Ga]CDS-1 zeolite can be applied for catalytic cracking reactions (1-hexene and ethylbenzene) and methanol-to-olefin (MTO) reaction as a novel solid acid catalyst.
Oil shale obtained from Kalynkara in Kazakhstan was investigated by powder XRD, XRF, SEM, TG-DTA, and EA. The XRD profiles indicated that the oil shale contained quartz (major component), CaSO4·2H2O, and Mg4Al2(OH)12CO2·H2O as minerals. The amount of organic matter in the oil shale was determined by TG-DTA and was approximately 19 wt% based on the weight loss in the temperature range of 473-823 K. Moreover, the H/C ratio determined by EA and TG-DTA was 0.86, indicating that the structure of the organic matter was similar to that of coal. We attempted to extract the organic matter from the oil shale in decalin at 373-623 K, but no significant amount of products was obtained.