Chromium–tungsten heterogeneous catalyst for esterification of palm fatty acid distillate to fatty acid methyl ester

•Chromium–tungsten mixed oxides solid catalyst synthesized via sol–gel.•Catalyst is active in esterification of palm fatty acid distillate to methyl esters.•The maximum methyl ester content is 86%.•Catalyst is stable for several cycles and separates easily from product mixture.

Chromium–tungsten mixed oxides heterogeneous catalysts were prepared and evaluated in the esterification of palm fatty acid distillate (PFAD) to produce fatty acid methyl ester (FAME). The reactions were conducted in a batch reactor at temperature range of 110–190 °C and catalysts were characterized by BET, SEM, TEM, FTIR and XRD. The effects of catalyst preparation conditions (metal ratio, calcination temperature and time), the influence of reaction conditions (temperature and time, methanol/PFAD molar ratio, catalyst dosage) and catalyst stability were studied. The prepared catalyst with formula CrWO2 (calcined at 600 °C for 3 h) gave the maximum FAME content of 86% at best reaction conditions (170 °C; 3 h, 2:1 methanol/PFAD molar ratio; 1.5 wt.% catalyst dosages) and can be recycled for several times. Thus, CrWO2 has good potentials as heterogeneous catalyst for FAME synthesis from high acid value oils.

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