Nano-Tubular Cellulose for Bioprocess Technology Development

Delignified cellulosic material has shown a significant promotional effect on the alcoholic fermentation as yeast immobilization support. However, its potential for further biotechnological development is unexploited. This study reports the characterization of this tubular/porous cellulosic material, which was done by SEM, porosimetry and X-ray powder diffractometry. The results showed that the structure of nano-tubular cellulose (NC) justifies its suitability for use in “cold pasteurization” processes and its promoting activity in bioprocessing (fermentation). The last was explained by a glucose pump theory. Also, it was demonstrated that crystallization of viscous invert sugar solutions during freeze drying could not be otherwise achieved unless NC was present. This effect as well as the feasibility of extremely low temperature fermentation are due to reduction of the activation energy, and have facilitated the development of technologies such as wine fermentations at home scale (in a domestic refrigerator). Moreover, NC may lead to new perspectives in research such as the development of new composites, templates for cylindrical nano-particles, etc

Catalytic upgrading of refinery cracked products by trans-hydrogenation: a review

The production of high premium fuel is an issue of priority to every refinery. The trans-hydrogenation process is devised to convert two low valued refinery cracked products to premium products; the conversion processes involve the combination of dehydrogenation and hydrogenation reaction as a single step process. The paper reviews the recent literature on the use of catalysts to convert low value refinery products (i.e. alkanes and alkynes or alkadienes) to alkenes (olefins) by trans-hydrogenation. Catalysts based on VOx, CrOx and Pt all supported on alumina have been used for the process. However, further studies are still required to ascertain the actual reaction mechanism, mitigating carbon deposition and catalyst deactivation, and the role of different catalysts to optimize the reaction desired products

Hydrodeoxygenation of Lignin-Derived Compound Mixtures on Pd-Supported on Various Oxides

International audienceAs a plethora of different unsaturated oxygenates is produced from the pyrolysis of biomass into bio-oil, understanding the role of competitive adsorption in catalytic upgrading is essential. To this end, the relative reactivities of representative molecules of key families within a single feed mixture were examined through reaction testing and in situ infrared spectroscopy characterization. The influence of the support (silica, ceria, zirconia, titania, and niobia) on the rate of elimination of hydroxyl and methoxy groups was evaluated on single compounds (phenol, m-cresol, and anisole) and binary mixtures (phenol/anisole and m-cresol/anisole). The removal of hydroxyl groups depends significantly on the support type. Pd supported on SiO2 and CeO2 favored ring hydrogenation resulting in the production of oxygenated products such as cyclohexanone/3-methylacylohexanone. The use of ZrO2, TiO2, and Nb2O5 as supports promotes the formation of benzene/toluene by hydrogenation of the carbonyl group of the tautomer intermediate formed or even direct deoxygenation. The reaction pathways for removal of methoxy groups also depend on the support. The demethylation route that yields methane and phenol and its further deoxygenation to benzene is proposed to take place over all catalysts, except on Pd/Nb2O5. Due to the superior oxophilicity of Nb cations, the niobia-supported catalyst greatly favors the direct deoxygenation, with formation of benzene and methanol (demethoxylation). The reaction with binary mixtures of phenol/anisole and m-cresol/anisole revealed that the hydroxyl groups react preferentially. Insight into the mode and strength of adsorption of the different molecules on the catalyst surface was obtained by DRIFTS analysis upon adsorption and desorption. The results indicate that under the HDO reaction conditions investigated phenol and m-cresol seem to adsorb more strongly on the catalyst surface and react more readily than anisole. Thus, this study shows that competitive adsorption is a predominant factor impacting product selectivity

Reaction pathways for the HDO of guaiacol over supported Pd catalysts: Effect of support type in the deoxygenation of hydroxyl and methoxy groups

International audienceThe effect of support type (SiO2, CeO2, ZrO2, TiO2, Nb2O5) on the removal of the different oxygenated functional groups (hydroxyl and methoxy) was investigated in the hydrodeoxygenation (HDO) of guaiacol over supported Pd catalysts at 573 K and atmospheric pressure. The product distribution depended on the support type, and three main reaction pathways were proposed: demethoxylation, demethylation and dehydroxylation. Demethoxylation yielding phenol was the dominant reaction pathway over all catalysts with only a minor contribution from the demethylation reaction taking place. However, significant dehydroxylation reaction was still observed for the catalysts having Pd supported on ZrO2, TiO2 and Nb2O5. Further conversion of phenol to cylohexanone was favored over SiO2 and CeO2-based catalysts, while benzene was only detected over ZrO2, TiO2 and Nb2O5, which is due to the presence of oxophilic cations. DRIFTS measurements were carried out to evaluate the adsorption mode and strength of guaiacol on the catalyst surface. The functional groups involved in adsorption of guaiacol included both hydroxyl and methoxy groups. At the reaction conditions, the hydroxyl group is strongly adsorbed to the catalyst surface and may block the catalytic sites, thus inhibiting further conversion of phenol and resulting in lower deoxygenation rates