Reactive separation processes applied to biodiesel production from residual oils and fats: Design, optimization and techno-economic assessment of routes using solid catalysts

Abstract

Three solid acid-catalyzed (SAC) processes for biodiesel production from residual oil and fats (ROFs) with HWSi/Al2O3 as catalyst were designed and optimized using Aspen Plus: simultaneous esterification, transesterification, and methanol separation based on catalytic distillation (CD) (process A) and catalytic absorption (CA) (process B), where CA has not yet been investigated in these conditions; and hydro-esterification industrial process using CD (process C1). For the first time, processes A, B and C based on SAC route were optimized and compared regarding to techno-economic and environmental aspects. Processes A and B were the most economically and eco-friendly options. Compared to process B, process A was the best option due to simpler flowsheet. Process A2 presented 25.6, 60.1, 4.6, 8.6, 52.6 and 62.8% lower capital, utilities (Cutil), operation, total annualized (TAC), waste treatment (Cwaste) and CO2 emission costs than process C1. A global optimization developed for process A saved 430 k$/year on TAC. After a heat integration, process B presented 4.9 and 10.8% lower Cutil and Cwaste than process A. Process A was also designed for FFA levels of 5–25 wt%, where the biodiesel break-even price remained competitive (0.48–0.75 $/kg) with diesel price.