Biomass to fuels: A water-free process for biodiesel production with phosphazene catalysts

Non-ionic triamino(imino)phosphoranes (phosphazenes) give excellent results as base catalysts for the water-free alcoholysis of vegetable fatty esters. Two phosphazene catalysts, with different intrinsic basicities, P1-t-Bu and P4-t-Bu, together with reaction parameters, such as temperature, alcohol/oil molar ratio, or catalyst concentration, have been studied. It was found that activity can be directly correlated to the basicity of the catalyst. Very high biodiesel yields (93–95% mol) were achieved under mild reaction conditions with methanol and ethanol. The catalyst can be recovered and recycled.

Graphical abstractNon-ionic triamino(imino)phosphoranes (phosphazenes) give excellent results as base catalysts for the water-free alcoholysis of vegetable fatty esters. Two phosphazene catalysts, with different intrinsic basicities, P1-t-Bu and P4-t-Bu, together with reaction parameters, such as temperature, alcohol/oil molar ratio, or catalyst concentration, have been studied. It was found that activity could be directly correlated to the basicity of the catalyst. Very high biodiesel yields were achieved under mild reaction conditions with methanol and ethanol. The catalyst can be recovered and recycled. Figure optionsDownload full-size imageDownload as PowerPoint slide