Optimization of high free fatty acid reduction in mixed crude palm oils using circulation process through static mixer reactor and pilot-scale of two-step process

Abstract

High free fatty acid (FFA) reduction in mixed crude palm oil (MCPO) was performed with methanol (MeOH) and sulfuric acid (H2SO4) as acid catalyst using the circulation process through static mixer reactor. In this study, the response surface methodology (RSM) was adopted to optimize the acid value in esterified oil after esterification process (first-step) in lab-scale. The results showed that acid value was reduced from 30mgKOHg−1 to 2mgKOHg−1, when 19.8vol.% MeOH, 2.0vol.% H2SO4, reaction temperature 60°C, 40Lh−1 of MCPO, 50min reaction time, and 5-m of static mixer in length, were used in the lab-scale. This recommended condition was used to develop the pilot-scale process in which the scaling up of the FFA reduction from 5L MCPO of lab-scale to 60L MCPO of pilot-scale, which was designed on the basis of a simple operation and maintenance. In the pilot-scale process, the lower 1mgKOHg−1 of acid value was achieved when it was conducted at the reaction time of 50min. In the base-catalyzed transesterification (second-step) of pilot-scale process, the 98.65wt.% of methyl ester purity was achieved when the following condition: 20vol.% MeOH, 8gKOHL−1 oil, and 60min reaction time at 60°C, was used to produce biodiesel.