Study Finds Microwave-Assisted Transesterification of Camelina Oil Consumes Less Than 10% of the Energy as Conventional Heating
Researchers at the University of New Mexico found in a study of the catalytic conversion of Camelina Sativa oil to biodiesel through both conventional heating and microwave radiation that the microwave-heating method consumed less than 10% of the energy to achieve the same yield as the conventional heating method. A paper on their work was published online in the ACS journal Energy & Fuels 15 November.
Transesterification of organic compounds to yield biodiesel can be achieved by the following methods: (1) conventional heating with acid, base catalysts, and cosolvents; (2) super- and subcritical methanol state without catalyst; (3) enzymatic method using lipases;19 and (4) microwave irradiation (with acid, base catalysts).
Among these methods, the conventional heating method requires longer reaction times with higher energy inputs and losses to the ambient. The super and subcritical methanol state operates in expensive reactors at high temperatures and pressures resulting in higher energy inputs and higher production costs. The enzymatic method requires longer reaction times. Microwave-assisted transesterification, on the other hand, is an energy-efficient and a quick process to produce biodiesel from different feedstocks.—Patil et al.
Their study evaluated microwave radiation as a nonconventional heat source for transesterification of Camelina Sativa oil using three different types of catalysts: homogeneous catalysts (NaOH and KOH), heterogeneous metal oxide catalysts (BaO and SrO), and sol-gel derived catalysts (BaCl2/AA and SrCl2/AA) for their efficacy in biodiesel production.
On the basis of energy consumptions in the transesterification processes with both conventional heating and microwave-heating methods evaluated in this study, the researchers estimated that the microwave-heating method consumes less than 10% of the energy to achieve the same yield as the conventional heating method. The fuel properties of camelina biodiesel produced were compared with those of the regular diesel and found to be conforming to the American Society for Testing and Materials (ASTM) standards.
Further studies on microwave-assisted transesterification kinetic at various conditions are necessary to elucidate the reaction mechanisms to determine the reaction rate constants and activation energies, which enable us to optimize and design energy-efficient transesterification processes for biodiesel production from various feedstocks.—Patil et al.
Prafulla D. Patil, Veera Gnaneswar Gude, Lucy Mar Camacho and Shuguang Deng (2009) Microwave-Assisted Catalytic Transesterification of Camelina Sativa Oil. Energy Fuels, Article ASAP doi: 10.1021/ef9010065