Glycerol as raw material to an Argentinian biorefinery

Abstract

Glycerol, the “co-product” in the biodiesel process, can be considered as a raw material to expand a biorefinery scheme. Selective reductions and oxidations and steam reforming of glycerol were studied to produce added-value chemicals and energetic compounds, and also to show a possible integration of processes into a biorefinery framework. Selective reductions of glycerol in gas phase produced: i) propylene glycol on Cu-Ce/Al2O3, reaching 99.8% conversion and 83.2% selectivity to propylene glycol; and ii) ethylene glycol on Ni/SiO2, achieving 100% conversion and 91% selectivity to ethylene glycol in the liquid fraction. These reduction reactions demand hydrogen, which can also be obtained by steam reforming of glycerol using Ni/Al2O3 promoted by adding compounds as Ce, Co, Mg, and Zr; the steam reforming also produced carbon oxides and methane, being possible to use the syngas (hydrogen plus carbon monoxide) and methane as energetic compounds and carbon dioxide to carbonylation. Selective oxidations of glycerol in liquid phase produced: i) dihydroxyacetone on Pt/K-FER, being the first active and selective monometallic catalyst for this transformation, improving the catalytic behavior by using Pt-Bi/K-FER, reaching 75.9% conversion and 93.9% selectivity to dihydroxyacetone; and ii) lactic acid on Cu/Al2O3, obtaining 99.8% conversion and 86.5% selectivity to lactic acid. From the strong link with the productive sector, one pilot plant to produce 100 t/y of propylene glycol from glycerol but versatile to also obtain acetol and/or ethylene glycol is in the final building stage, and another one for reforming glycerol to produce the hydrogen demanded for those reduction processes was finished. Consequently, glycerol was converted to propylene glycol, ethylene glycol, hydrogen, dihydroxyacetone, lactic acid, syngas, carbon dioxide, and methane; therefore, the possible integration of the corresponding processes allows consider the co-product of biodiesel as a compound to expand a biorefinery scheme.