Mixed metal oxides are promising heterogeneous catalysts for biofuel production from lipids via alcoholysis, however, the impact of solid acidity and/or basicity on reactivity is comparatively poorly understood. Two systematically related families of MgO–ZrO2 mixed oxide catalysts were therefore prepared by different synthetic routes to elucidate the impact of surface acid-base properties on catalytic performance in the transesterification of tributyrin with methanol. The resulting materials were characterized by TGA-MS, ICP-OES, N2 porosimetry, XRD, TEM, XPS, DRIFTS, and CO2-temperature-programmed desorption (TPD). MgO–ZrO2 catalysts prepared by both non-aqueous impregnation and citric acid-mediated sol–gel routes exhibit excellent activity and stability. The citrate routes favor highly dispersed MgO and concomitant Lewis acid-base pair formation at the interface with zirconia. However, for both the citrate and impregnation routes, tributyrin transesterification occurs over a common, strongly basic MgO active site.
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- solid base
- mixed oxide