The Peoples’ Friendship University of Russia’s (RUDN) chemist has synthesised a catalyst to produce gamma-valerolactone, a “green” biofuel.
The catalyst, based on zirconium dioxide and zeolite, has shown high efficiency in converting the waste of wood plant materials, methyl levulinate, to gamma-valerolactone.
Lignocellulose is sourced from agricultural waste and wood processing. Methyl levulinate can be firstly derived from lignocellulosic biomass, which is then converted into gamma-valerolactone based on noble metal catalysts.
Gamma-valerolactone has significant potential for high-caloric-value liquid biofuel that is compatible with traditional petroleum fuels. It can be used for modern vehicles without major engine modifications. The high cost of catalysts containing platinum, palladium and ruthenium is one of the main obstacles to the mass production of this cheap biofuel. Therefore, chemists are trying to create catalysts based on available metals.
Rafael Luque, director of the scientific centre of RUDN Joint Institute for Chemical Research, obtained a new catalyst from easily available substances—zeolite and zirconium dioxide. Zirconium is found in nature much more often than noble metals, and its extraction is simpler.
About 300,000 tons of zirconium are extracted annually, compared to 20 tons per year for ruthenium. The chemists chose zeolites as a catalyst carrier that consists of silicon, aluminium and oxygen.
Zeolites are attractive materials for the preparation of nanocomposite materials and catalysts due to their open frame-cavity structure with various acid sites. By mechanochemical mixing of zirconium salt and zeolite, followed by heat treatment, the RUDN chemist and his colleagues managed to obtain a catalyst with zirconia nanoparticles.
“Absolutely, biofuels have a low profit margin based on their low market value and the design of optimum processes in terms of catalysts and methodologies is essential in order to achieve a positive techno-economic balance.”
The authors note that, in the future, the hydrogenation of methyl levulinate in a proton solvent environment using inexpensive zirconium-zeolite catalysts may become the basis of technological processes for converting lignocellulosic biomass into second-generation biofuel.