Carbide and Nitride Supported Methanol Steam Reforming Catalysts: Parallel Synthesis and High Throughput Screening

A series of Mo₂C and Mo₂N supported catalysts have been synthesized using a parallel synthesis and high throughput screening approach. The high surface area Mo₂C and Mo₂N supports were prepared using temperature programmed reaction methods. Metals including Co, Cu, Fe, Ni, Pd, Pt, Ru, and Sn were impregnated onto these supports using a synthesis system. Methanol steam reforming (MSR) activities and selectivities for these materials were evaluated using a high throughput-screening reactor. The support type, metal type and concentration, and metal precursor type influenced the activity and selectivity patterns. Of more than 400 materials that were synthesized and evaluated, the Pt/Mo₂N, Pt–Ni/Mo₂N, Pt–Fe/Mo₂N, and Pd–Fe/Mo₂C catalysts possessed the highest activities. Some of these formulations were more active than a commercial Cu/Zn/Al₂O₃ catalyst, however, the CO₂ selectivities were typically lower. At similar conversions, materials that were highly active were not selective while the less active materials were very selective. Many of the highly active catalysts included noble metals while the highly selective catalysts included base metals.     

Biohydrogen and biogas production from mashed and powdered vegetable residues by an enriched microflora in dark fermentation

This study conducted the utilization of vegetable residues by an enriched microflora inoculum to produce biohydrogen via anaerobic batch reactor. Dark fermentation processes were carried out with 3 kinds of vegetable residue substrates including broccoli (Brassica oleracea var. italica.), onion (Alium cepa Linn.), and sweet potato (Ipomoea batatas (L.) Lam). Vegetable wastes were pretreated into 2 forms, i.e. mashed and powdered vegetable, prior to the fermentation. The substrate used for the biohydrogen production were vegetable residues and inoculum at the vegetable residues/inoculum ratio of 1:1 (based on TS). The digestion processes were performed under 120 rpm speed of shaking bottle in the incubator with control temperature of 35^?C. In this work, the maximum hydrogen production was achieved by anaerobic digestion at mashed onion with bioreactor inoculum that produced total hydrogen of 424.1 mL H₂ with hydrogen yield and hydrogen concentration of 151.67 mL H₂/g VS_added and 43.54%, respectively. In addition, the hydrogen production continues took only 7 days for the vegetables blended with the bioreactor inoculum. Finally, it was found that the high potential of degradation of vegetable wastes an enriched microflora in dark fermentation also showed alternative solution to eliminate agricultural wastes to produce green energy.     

Oxidative Hydrolysis of Cellobiose to Glucose

Abstract  

Cellobiose hydrolysis into glucose was chosen as a model system for cellulose breakdown to investigate glycosidic bond cleavage. The hydrolysis was enhanced by increased acidity in an inert gas medium, while air-assisted hydrolysis with a neutral solution achieved over 70% glucose yield. Hydrogen peroxide, as a stronger oxidant than air, converted cellobiose to carboxyl compounds, which lowered the glucose selectivity. At 150 °C, the selectivity from cellobiose to glucose was very low on porous γ-Al₂O₃ supported catalysts, even lower than without a catalyst. When the active metals were prepared on non-porous supports such as spherical alumina (α phase), the overall yield of glucose was dramatically improved at 120 °C. Similar improvements were obtained for another disaccharide model, sucrose, which achieved greater than 90% sucrose conversion with selectivity in excess of 90% at 80 °C.