This research examines the use of solid metal catalysts to solve two interrelated problems associated with current biodiesel process technologies: the use of toxic chemicals in the conventional production process and the economic feasibility of processing feedstock with high water and free fatty acid content. The potential gains include the reduction of toxic chemicals in the process, the elimination of costly pre-treatment for low cost feedstocks, and a major reduction in product purification steps needed at the end of the process. Project objectives include laboratory tests using solid metal oxide catalysts to determine the conversion rate of free fatty acid at various concentrations, to investigate the effect of feedstock water content on yield and quality, to conduct catalyst longevity trials with low grade feedstocks, and to assess process technology's ability to meet quality specifications. Our approach is to use a set of solid metal oxide catalysts that eliminates the need for toxic chemicals, expensive pre-treatment of feedstocks, and post product processing. This continuous, heterogeneous catalyst process at near critical temperature and pressure has the potential to efficiently convert a wider variety of feedstock with higher concentrations of free fatty acid and water into high quality biodiesel and glycerin co-products. Highly effective solid catalysts in an ethanol based, continuous process will eliminate the use of toxic chemicals and eliminate several energy intensive processing and purification steps. Our technology uses solid metal oxide catalysts at near critical temperatures and pressures in a continuous flow process achieving very high conversions of all available feedstocks and high fatty acids with short reaction times and reduced water use. A solid catalyst processing technology will solve several key processing disadvantages in the biodiesel industry while creating glycerol market opportunities for biodiesel producers. Elimination of process steps and once-through chemical use will decrease both the fixed and variable costs of manufacturing biodiesel. The biodiesel and glycerin produced will be of high purity thereby producing negligible wastes. The proposed process has the promise of expanding the use of marginal feedstock supplies while dramatically reducing production costs and water usage. OBJECTIVES: The goal of this project is to evaluate the conversion efficiency and longevity of seven highly effective solid catalysts in converting standardized feedstock mixtures with varying concentrations of free fatty acid and water at near critical reaction conditions. The research will demonstrate the relative effectiveness of our solid catalyst, continuous process in a fixed-bed, lab-scale reactor operating at near critical temperatures and pressures. Research Objectives: 1. Investigate Catalyst Effectiveness for Esterification of Free Fatty Acids. Catalysts that can convert both Free Acid and Triglycerides in one step would decrease capital, operating, and maintenance costs to the biodiesel industry. Tests will be conducted to determine the ability conversion of FFA at various concentrations. The maximum conversion attainable will be assessed. 2. Investigate Effect of Water Content in Feedstock on Yield and Quality. Water is problematic for conventional processors because it can create FFA through hydrolysis of oil and cause soap formation. By running various grades of reactants we will assess our processes tolerance of water on the front end and gather data on whether our catalysts remain truly insoluble. 3. Conduct Catalyst Longevity Trials with Low-Grade Feedstocks. While batch tests already show complete conversion of free fatty acids, these experiments will confirm each catalysts ability to handle multiple alternative feedstocks and speak to the life of the catalysts. These low-grade feedstocks will contain moisture and impurities with the most potential to cause loss of catalyst activity. 4. Assess Technologies Ability to Meet Quality Specifications for Biodiesel and Glycerol. Heterogeneous catalysts are needed to more readily meet ASTM specifications for biodiesel quality and to create a higher value glycerol co-product. Indicators of the quality of both these products must be assessed for this technology to be deemed viable. APPROACH: Our bench-scale system is a continuous high pressure packed-bed reactor capable of operating at near critical temperature and pressure. This will be a high pressure process employing the identified catalysts in a packed bed. The composition of the biodiesel and glycerol products will be determined in our own laboratory with a calibrated gas chromatograph, and verifying the results at ASTM certified testing facilities. The identified catalysts will be compared based on activity, robustness, catalyst life, ease of regeneration, cost and availability considerations. 1.Investigate Catalyst Effectiveness for Esterification of Free Fatty Acid. Mild bases, such as the metal oxides under investigation, are known to exhibit amphoteric behavior depending on reaction conditions. Reaction rates and yields will be studied as a function of FFA content of the feedstock. A mixture of Palmitic, Oleic, Linoleic, Linolenic acids will be prepared as these are the most common FFAs in rendered oil and waste oil feedstock. The reactor will be charged with an HPLC pump with 4 independently metered feeds. The FFA mixture will be metered into the reactor with soy oil feedstock and alcohol. Various FFA contents will be tested given a uniform space velocity for all catalysts. Inflection points will be studied with further FFA compositions as necessary. The 3 best performing catalysts will be run at increasing residence times of 25 min, 35 min, and 45 min to identify maximum conversion of FFA possible. 2.Investigate Effect of Water Content in Feedstock on Yield and Quality. In conventional alkaline homogenous reactors, FFA produces soap due to the ionized metals and the presence of water. The soap decreases yield, slows conversion, and complicates product purification. Our catalysts will be subjected to varying levels of moisture to determine effect on conversion and product quality. Various moisture contents will be analyzed with the 3 most promising catalysts from results of the first investigation. The reaction yield will be studied with GC analysis and samples will be sent offsite for metals and soap analysis. 3.Conduct Catalyst Longevity Trials with Low Grade Feedstocks. Rendered and recycled oils have a higher propensity to cause loss of catalyst life due to various impurities. The three most promising catalysts will be subjected for up to 200 hours of continuous processing with the following low grade feedstocks: Trap Grease, Yellow Grease, and No. 2 Tallow. These feedstocks were chosen because they typically have considerable Moisture, Insoluble and Unsaponified content. The yield will be monitored with GC analysis at 10 hour intervals to determine loss of catalyst activity. 4.Assess Technology Ability to Meet Quality Specifications for Biodiesel and Glycerol. Biodiesel quality, refinability. GC analysis will be conducted to determine residual acid content, total glycerin, free glycerin and mono, di, and triglyceride content of biodiesel produced
