Biodiesel Production from Waste Cooking Oil Using Anion-Exchange Resin as Both Catalyst and Adsorbent

A novel production process of biodiesel fuel was developed using an expanded-bed reactor packed with an anion-exchange resin having catalytic and adsorption abilities. Waste cooking oil was used as a cheaper feedstock, and methanol was added at the stoichiometric molar ratio of 3:1. The main constituent of the feedstock, triglyceride was completely converted to the biodiesel by the resin's catalytic ability. The impurities of the feedstock, free fatty acid, water, and dark brown pigment were removed from the product by the adsorption on the resin. In addition, the by-product glycerin was also removed from the product by the adsorption on the resin. The product eluted from the reactor was directly used for the standard tests of the biodiesel properties. The eluted product almost met the biodiesel quality standards (EN14214 in Europe and ASTM D6751 in North America). Thus, the proposed system permitted the simple production of biodiesel from the waste cooking oil without the upstream processing to remove the impurities (free fatty acid and water) and the downstream processing to remove the catalyst and by-products (glycerin and soap).