Novel Two-Step Process for the Production of Renewable Aromatic Hydrocarbons from Triacylglycerides

A two-step process was developed for the production of aromatic hydrocarbons from triglyceride (TG) oils. In the first reaction step, TG (soybean) oil was noncatalytically cracked and purified by distillation to produce an organic liquid product (OLP). The resulting OLP was then converted into aromatic compounds in a second reaction using a zeolite catalyst, HZSM-5. In this second reaction, three main factors were found to influence the yield of aromatic hydrocarbons: the SiO2 center dot Al2O3 ratio in the HZSM-5, the reaction temperature and the OLP-to-catalyst ratio. Upon cursory optimization, up to 58 w/w% aromatics were obtained. Detailed analyses revealed that most of the alkenes and carboxylic acids, and even many of the unidentified/unresolved compounds, which are characteristic products of noncatalytic TG cracking, were reformed into aromatic hydrocarbons. Instead of BTEX compounds, which are the common products of C-2-C-8 alkene and other feedstock reforming with HZSM-5, longer-chain alkylbenzenes dominated the reformate (along with medium-size n-alkanes). Another novel feature of the two-step process was a sizable (up to 13 w/w%) concentration of alicyclic hydrocarbons, both cyclohexanes and cydopentanes. Thus, this novel two-step process may provide a new route for the production of renewable aromatic hydrocarbons as an important coproduct with transportation fuel products.