Vanadium phosphate catalysts for biodiesel production from acid industrial by-products

► Biodiesel was produced from low value industrial by-products. ► VPO are active catalysts for both esterification and transesterification reactions. ► Water formed in esterification reaction hinder biodiesel production. ► Reduction of vanadium species is responsible by catalysts deactivation. ► Spent catalysts can be regenerated by recalcination.