Optimization of a two-step process for the production of ASTM-standard biodiesel from refurbished oils and fats.

摘要

Biodiesel can be produced from low cost feedstock such as refurbished waste fats and oil, which contain significant amounts of free fatty acid (FFA), by using two-step process. The first step converts the FFA by acid catalysis, and the second step converts the triglycerides (TG) by base catalysis. Currently, the major challenge for the industrial production of biodiesel is to optimize biodiesel yield and meet ASTM standards.; Experiments have been performed to optimize the reaction conditions. The process variables studied were: FFA content in feedstock, water content, type and amount of acid catalysts, type of base catalysts, salts and their types, and temperature. The experimental parameters studied were: (1) FFA content (0, 10, 15, 20, 30, and 50 mass%), (2) H2SO4 (1.0 and 2.0 wt% of feed) and HCl (0.74 wt% of feed), (3) NaOH (1.0 wt%), KOH (1.4 wt%), and NaOCH3 (1.35 wt% of feed), (4) temperature for the acid step (60°C), and for the base step 23°C and 40°C), (5) water content (water produced from neutralization, and water produced from neutralization as well as from 20% FFA). The optimum conditions found were: (1) FFA content up to 10--15% max., (2) H2SO 4 (1.0 wt%) and HCl (0.74 wt%), (3) NaOH (1.0 wt%), NaOCH 3 (1.35 wt%), and KOH (1.4 wt%), (4) acid step temperature (60°C) and base step temperature (23°C), and Feed/THF/CH3OH volume ratio 1:1:1. These conditions produced biodiesel, which meets ASTM standards.