Thermal Cracking of Canola Oil: Reaction Products in the Presence and Absence of Steam

摘要

The product distribution obtained from the thermal cracking of canola oil was studied at atmospheric pressure in a fixed-bed reactor in the temperature range 300-500℃ and gas hourly space velocity (GHSV) in the range 3.3-640 h~(-1) over inert materials and in the presence and absence of steam. Results showed that canola oil conversions were high (54-100 wt %) and depended strongly on the operating variables. Products essentially consisted of C_4 and C_5 hydrocarbons, aromatic and C_6~+ aliphatic hydrocarbons, and C_2-C_4 olefins, as well as a diesellike fuel fraction and hydrogen. GC—MS analyses showed that product distribution as well as the lengths of the carbon chain of hydrocarbons and oxygenated hydrocarbons depended strongly not only on the cracking temperature and space velocity but also on whether cracking was conducted in the presence or absence of steam. On the other hand, cracking over inert materials showed that both conversion and product distribution were completely independent of morphology of the cracking surface. A reaction scheme has been proposed to account for the product distribution obtained from the thermal cracking of canola oil. The observed changes in both canola oil conversion and product distribution with changes in the operating variables were found to be consistent with the reaction scheme.