By Annel K. Greene, PhD
Vice Center Director, Clemson University
Animal Co-Products Research and Education Center
Editor’s Note – Render is introducing this new column, ACREC Solutions, which will highlight some of the activities, researchers, and projects at the Animal Co-Products Research and Education Center.
Dedicated in March 2006 after a collaborative agreement between the Fats and Proteins Research Foundation and Clemson University, the center will focus on new or enhanced and safe uses of animal by-products and its processes.
Bioenergy researcher Dr. James G. Goodwin Jr., a member of the Clemson University Animal Co-Products Research and Education Center (ACREC) team, is working to find solutions to the high cost of catalysis in biodiesel manufacturing.
As department chair of the Clemson University Department of Chemical and Biomolecular Engineering, Goodwin and his colleagues conduct a variety of bioenergy related studies. Goodwin specializes in “kinetics, heterogeneous catalysis, isotopic transient kinetic analysis of surface catalyzed reactions, hydrocarbon synthesis and oxidation, and natural gas conversion” and brings this wealth of knowledge to the study of economical conversions of animal and vegetable fats into biodiesel. He has served as president of the Southeastern Catalysis Society, is active in the North American Catalysis Society, and has served on the advisory boards and committees of numerous other international organizations related to natural gas, bioenergy, and chemical catalysis.
Catalysts are substances that drive a reaction to proceed at a commercially feasible rate. In the formation of biodiesel, fats and oils are mixed with an alcohol such as methanol or ethanol in the presence of a catalyst. The end result of the reaction is biodiesel (technically a monoalkylester) and glycerol. The choices for catalyst for this reaction have been strong alkali (such as sodium hydroxide or potassium hydroxide) or strong liquid acid (such as sulfuric acid). Traditionally, the alkaline catalyst has been used because of better reaction rates. However, use of alkali as a catalyst has its problems. The catalyst cannot be reused in the reaction and, thus, purchase of additional catalyst is an expensive cost for biodiesel manufacturers. Another problem encountered is the formation of soap from the reaction of free fatty acids with the alkali. Soap in the biodiesel affects quality and efforts to remove it from the product add to the manufacturing cost.
The other major catalyst, strong liquid acid, has a number of difficulties as well. First, strong liquid acids do cause the reaction to proceed to form biodiesel but reaction activity is lower than with the alkali catalysts. The corrosive nature of strong liquid acids cause additional environmental, transport, handling, and use problems.
Goodwin realized that another category of catalysts existed that may prove economically and environmentally useful for the biodiesel industry – solid acids. Solid acids do not have the corrosive and environmental problems associated with the strong liquid acid catalysts. Solid acids also could allow manufacturers to convert fats and oils to biodiesel with fewer reaction and separation steps. Cost savings would make biodiesel more profitable.
Armed with preliminary research that proved that solid acids would cause reaction catalysis of model compounds, Goodwin and his research team have continued their studies to understand the underlying intricacies of solid acid catalysts and to learn the best way of utilizing them. Solid acid catalysts are heterogenous catalysts that have an infrastructure of pores leading to the catalysis reaction on the active sites. The architecture of these pores is of great importance since both reactant molecules must come into contact with the active catalytic sites in order for the reaction to proceed. A small molecule like methanol can flow into the pores fairly easily; however, if the pores are too small, larger chemical moieties such as triglycerides and free fatty acids cannot reach the active sites. Additionally, water generated in the reaction can poison the catalyst.
In order to overcome the problem of water, Goodwin’s research team is investigating use of a three-phase reactor where the catalyst is a solid, the fat is a liquid, and the methanol is a gas. This system is operated at an elevated temperature, which allows higher reaction rates and allows the unreacted methanol and water to be removed by distillation, thereby avoiding the problems of catalyst poisoning. Results of the three-phase reactor studies using poultry fat have been very promising and are yielding important data for comparison to traditional batch reactor systems.
Although still in the laboratory research and development phase, Goodwin’s research is offering a unique and fresh approach to biodiesel catalysis. The three-phase reaction system with solid catalyst has the potential to greatly reduce overall processing costs in biodiesel manufacturing and thus, decrease overall biodiesel production costs. The research team has spent more than three years systematically evaluating different solid acid catalysts under a variety of reaction conditions in order to learn more about the mechanisms of solid catalyst function. Although this may sound easy on the surface, reports of the work include such tongue-tying terminology as “calcined tungstated zirconia,” “NH3 desorption profile,” “monochromatic powder X-ray diffractograms,” “diffractometer using Cu Ká radiation,” and other complex chemical lingo.
Goodwin’s research team is studying the underlying mechanisms by which these catalysts function with the goal of learning how to custom design the optimum catalyst and reaction process for the most economical manufacture of biodiesel. Information gained by this study could allow greater efficiency and cost-reduction in biodiesel production.
The ACREC is very proud that the preeminent biodiesel researcher Goodwin and his team are working to find solutions for optimizing the use of animal fats in the manufacture of biodiesel.
ACREC Solutions - February 2007 Render