Electronic Thesis and Dissertation Repository

Degree

Master of Engineering Science

Program

Chemical and Biochemical Engineering

Supervisor

Anand Prakash

Abstract

Biodiesel, derived from plant oils and animal fats is an attractive alternative fuel to fossil-based diesel as it is biodegradable, non-toxic, renewable, and has a low emission profile. Industrial production of biodiesel faces major challenges including limited supply of raw material and high cost of feedstock, which accounts for 60-80% of total production cost. Economic feasibility for biodiesel can be improved by using inexpensive raw materials such as waste frying oils and non-edible oils. However, these low quality feedstocks contain significant amounts of free fatty acids (FFA) which reacts with a base to produce soap hindering product separation and reduce product yield. The problem of soap formation can be avoided by adding a pretreatment step to convert FFA in oily feed to alkyl esters by esterification reaction.

This study investigates esterification of FFA using both homogeneous and heterogeneous acid catalysts under mild temperature and pressure conditions in a batch and semi-batch reactor. While homogeneous acid catalyst shows high activity leading to high conversion in less time, there is need for neutralization and water wash to remove residual acid from product. To overcome these problems solid acid catalysts were selected and tested for activity, selectivity and durability. It is demonstrated that a nonporous polymer gel type catalyst from Dow Chemical (BD 20) provides good activity and low deactivation rate compared to other catalysts. This catalyst is recommended for further testing for commercial application. Appropriate kinetic models have been proposed reactor development and modeling attempts.


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