Valorization of glycerol as a key in the environment of biorefineries

DANGELO, M.A.; BECCARIA, AJ; IGLESIAS, AA; COMELLI, R.A.

Los Cabos, Baja California

Congreso; First Iberoamerican Congress on Biorefineries; 2012

Glycerol, the co-product obtained in the biodiesel process, can play an important role as one key-compound in the framework of future biorefineries. Chemical and biological approaches were developed. Reactions of selective oxidation, hydrogenolysis, and steam reforming of glycerol were studied in order to valorize it and to obtain dihydroxyacetone, propanediols, and hydrogen, respectively. Dihydroxyacetone was produced chemically by selective oxidation of glycerol on Pt impregnated on potassium ferrierite being it an original result because of Pt/C is not selective towards that product needing a second metal to obtain dihydroxyacetone. The biological procedure to convert glycerol into dihydroxyacetone was designed after molecular cloning of the gene coding for glycerol dehydrogenase in Escherichia coli, followed by the homologous expression and purification of the recombinant enzyme. By considering the hydrogenolysis reaction in liquid phase using a commercial copper chromite, the 1,2-propanediol yield was improved conducing the reaction in two steps, the first one in mild conditions and without hydrogen, and the second one with hydrogen pressure. Both prepared Pt/W/Zr(OH)4 and Pt/W/ZrO2 catalysts allowed to obtain 1,3-propanediol, depending the ratio of propanediols on the preparation technique of these catalysts. The steam reforming of glycerol to produce hydrogen took place on Ni impregnated on alumina catalysts. The catalytic behavior depended on the operating conditions; comparing after 4 hours-on-stream and 5 h-1 WHSV, conversion increased by increasing temperature, while the largest hydrogen selectivity was obtained at 650ºC. Another way to valorize glycerol is its use as carbon nutrient for growing genetically transformed microorganisms producing high-value recombinant proteins.Escherichia coli, followed by the homologous expression and purification of the recombinant enzyme. By considering the hydrogenolysis reaction in liquid phase using a commercial copper chromite, the 1,2-propanediol yield was improved conducing the reaction in two steps, the first one in mild conditions and without hydrogen, and the second one with hydrogen pressure. Both prepared Pt/W/Zr(OH)4 and Pt/W/ZrO2 catalysts allowed to obtain 1,3-propanediol, depending the ratio of propanediols on the preparation technique of these catalysts. The steam reforming of glycerol to produce hydrogen took place on Ni impregnated on alumina catalysts. The catalytic behavior depended on the operating conditions; comparing after 4 hours-on-stream and 5 h-1 WHSV, conversion increased by increasing temperature, while the largest hydrogen selectivity was obtained at 650ºC. Another way to valorize glycerol is its use as carbon nutrient for growing genetically transformed microorganisms producing high-value recombinant proteins.