Design and economic analysis of biodiesel production process of simultaneous supercritical transesterification and partial hydrogenation using soybean oil with Pd/Al2O3 catalyst

Abstract

A kinetic study of the simultaneous supercritical transesterification and partial hydrogenation (SSTPH) process using soybean oil with Pd/Al2O3 catalyst was conducted. In addition, process design and economic analysis were conducted to investigate the profitability of three different continuous biodiesel production processes, each with a production capacity of 40,000 tonnes/h, including a conventional supercritical process, SSTPH process using Cu catalyst, and SSTPH process using Pd/Al2O3 catalyst. The contents of methyl oleate in the biodiesel products from the three processes were 22.9, 56.9, and 77.9 wt%, respectively. It was found that the total manufacturing costs for the SSTPH processes were higher than that of the conventional supercritical process due to partial hydrogenation. However, the total capital investment for the SSTPH process with Pd/Al2O3 was the lowest owing to the mild reaction condition. Overall, the SSTPH process using Pd/Al2O3 was the most economically feasible. Sensitivity analysis of the net present values (NPVs) was conducted according to the material prices and the plant capacity. The results of the sensitivity analysis show that the NPVs for the three processes are most sensitive to the biodiesel price. Consequently, the SSTPH process with Pd/Al2O3 had the lowest break-even biodiesel price despite the same price of biodiesel.