ABSTRACT
Abstract In this paper the continuous deoxygenation of biorenewable feeds for diesel fuel production is addressed. The model reactant, ethyl stearate (stearic acid ethyl ester, C20H40O2) is deoxygenated by removal of a carboxyl group via decarboxylation and/or decarbonylation reactions yielding an oxygen-free diesel fuel compound, heptadecane. The reaction was carried out in a fixed-bed tubular reactor over a heterogeneous catalyst under elevated temperatures and pressures. The effect of catalyst pretreatment and catalyst mass as well as influence of reaction temperature were investigated. Introduction Currently significant research effort is devoted to developing environmentally friendly liquid fuels from renewable sources. Natural oils and fats are produced via extraction or pressing of renewable materials such as vegetable and animal feeds. The natural oil and fats consist primarily of triglycerides (98%), which are made up of a glycerol moiety and three fatty acid moieties[1]. Typically fatty acids in vegetable oils and animal fats have a straight hydrocarbon chain with carbons varying from C6 to C24, the chain can be saturated, monounsaturated or polyunsaturated, Table 1 [2,3]. Diesel fuel compounds derived from crude oil generally have 10-20 carbon atoms , thus removal of the carboxyl group from the fatty acid molecule would result in a paraffinic hydrocarbon similar to fossil diesel compounds. The paraffinic fuel compounds, converted from fatty acids and their derivates, would have a superior cetane number compared to both fossil diesel compounds and the conventional biodiesel compounds, FAME, produced via the transesterification method [4]. Furthermore, fatty acid derived fuels are very ecologically benign, e.g. they exhibit a low sulphur and aromatic content and are biodegradable [5].
