Dongshen Tong

Catalytic conversion of lignocellulosic biomass to fine chemicals and fuels

Lignocellulosic biomass is the most abundant and bio-renewable resource with great potential for sustainable production of chemicals and fuels. This critical review provides insights into the state-of the-art accomplishments in the chemocatalytic technologies to generate fuels and value-added chemicals from lignocellulosic biomass, with an emphasis on its major component, cellulose. Catalytic hydrolysis, solvolysis, liquefaction, pyrolysis, gasification, hydrogenolysis and hydrogenation are the major processes presently studied. Regarding catalytic hydrolysis, the acid catalysts cover inorganic or organic acids and various solid acids such as sulfonated carbon, zeolites, heteropolyacids and oxides. Liquefaction and fast pyrolysis of cellulose are primarily conducted over catalysts with proper acidity/basicity. Gasification is typically conducted over supported noble metal catalysts. Reaction conditions, solvents and catalysts are the prime factors that affect the yield and composition of the target products. Most of processes yield a complex mixture, leading to problematic upgrading and separation. An emerging technique is to integrate hydrolysis, liquefaction or pyrolysis with hydrogenation over multifunctional solid catalysts to convert lignocellulosic biomass to value-added fine chemicals and bio-hydrocarbon fuels. And the promising catalysts might be supported transition metal catalysts and zeolite-related materials. There still exist technological barriers that need to be overcome (229 references).

Acid-activated and WOx-loaded montmorillonite catalysts and their catalytic behaviors in glycerol dehydration

Abstract The use of H 2 SO 4 -, HCl-, H 3 PO 4 -, and CH 3 COOH-activated montmorillonite (Mt) and WO x /H 3 PO 4 -activated Mt as catalysts for the gas-phase dehydration of glycerol was investigated. The WO x /H 3 PO 4 -activated Mt catalysts were prepared by an impregnation method using H 3 PO 4 -activated Mt (Mt-P) as the support. The catalysts were characterized using powder X-ray diffraction, Fourier-transform infrared spectroscopy, N 2 adsorption-desorption, diffuse reflectance ultraviolet-visible spectroscopy, temperature-programmed desorption of NH 3 , and thermogravimetric analysis. The acid activation of Mt and WO x loaded on Mt-P affected the strength and number of acid sites arising from H + exchange, the leaching of octahedral Al 3+ cations from Mt octahedral sheets, and the types of WO x (2.7 ≤ x ≤ 3) species (i.e., isolated WO 4 /WO 6 -containing clusters, two-dimensional [WO 6 ] polytungstates, or three-dimensional WO 3 crystals). The strong acid sites were weakened, and the weak and medium acid sites were strengthened when the W loading on Mt-P was 12 wt% (12%W/Mt-P). The 12%W/Mt-P catalyst showed the highest catalytic activity. It gave a glycerol conversion of 89.6% and an acrolein selectivity of 81.8% at 320 °C. Coke deposition on the surface of the catalyst led to deactivation.

Article (Special Issue on Nanoscience and Catalysis)Acid-activated and WOx-loaded montmorillonite catalysts and their catalytic behaviors in glycerol dehydration

Abstract The use of H 2 SO 4 -, HCl-, H 3 PO 4 -, and CH 3 COOH-activated montmorillonite (Mt) and WO x /H 3 PO 4 -activated Mt as catalysts for the gas-phase dehydration of glycerol was investigated. The WO x /H 3 PO 4 -activated Mt catalysts were prepared by an impregnation method using H 3 PO 4 -activated Mt (Mt-P) as the support. The catalysts were characterized using powder X-ray diffraction, Fourier-transform infrared spectroscopy, N 2 adsorption-desorption, diffuse reflectance ultraviolet-visible spectroscopy, temperature-programmed desorption of NH 3 , and thermogravimetric analysis. The acid activation of Mt and WO x loaded on Mt-P affected the strength and number of acid sites arising from H + exchange, the leaching of octahedral Al 3+ cations from Mt octahedral sheets, and the types of WO x (2.7 ≤ x ≤ 3) species (i.e., isolated WO 4 /WO 6 -containing clusters, two-dimensional [WO 6 ] polytungstates, or three-dimensional WO 3 crystals). The strong acid sites were weakened, and the weak and medium acid sites were strengthened when the W loading on Mt-P was 12 wt% (12%W/Mt-P). The 12%W/Mt-P catalyst showed the highest catalytic activity. It gave a glycerol conversion of 89.6% and an acrolein selectivity of 81.8% at 320 °C. Coke deposition on the surface of the catalyst led to deactivation.