Biodiesel is a renewable petroleum diesel substitute whose use can improve air quality and help combat global warming. We propose to test the feasibility of using a novel and innovative process to synthesize biodiesel that could change the economics and commercial practices of the biodiesel industry. Our research will evaluate the feasibility of using a novel, highly efficient heterogeneous zirconia-based catalyst in a continuous flow packed-bed reactor for synthesizing biodiesel from a variety of feedstocks. The surface chemistry of zirconia is dominated by Lewis acid-base chemistry, which will allow for the controlled adsorption of acid or base moieties that can be used for catalysis of both esterification and transesterification reactions. In this research, both base, acid and unmodified forms of zirconium dioxide will be evaluated at elevated temperature and pressure for efficient, continuous transesterification of triglycerides (TGs) and esterification of free fatty acids. Phase I research will test the capability of this catalyst to produce biodiesel using a variety of feedstocks (i.e. soybean oil, algae oil, yellow grease, beef tallow and acidulated soapstock) without significant catalyst deterioration over extended periods of use. Furthermore, we will purposefully foul the catalyst with dirty feedstocks and evaluate if the catalyst can be regenerated by pyrolysis of adsorbed organic matter in order to restore its original catalytic activity. If successful, we believe this research will overcome the most significant limitations currently experienced by the biodiesel industry, namely the difficulty in using inexpensive feedstocks that contain high levels of free fatty acids, the necessity to continuously add catalyst to the reaction (in either batch or semi-continuous production modes), resulting in the need to dispose of waste products harmful to the environment and eliminating the need for extensive washing of the biodiesel with water. If successful the proposed fixed bed catalysts should stimulate use of inexpensive feedstocks, thereby lowering the cost of biodiesel production significantly. In summary, a successful phase I project will demonstrate the feasibility of using zirconia at elevated temperature and pressure to change the economics of biodiesel production and expand its role as a renewable, environmentally friendly energy source. OBJECTIVES: Zirconia (zirconium dioxide) is a chemically and thermally stable transition metal oxide widely used in a variety of metallurgical and chromatographic applications. This metal oxide is chemically stable over the entire pH range and at elevated temperatures and pressures. Chemically, its surface is dominated by Lewis acid-base chemistry. The use of various metal-oxides including titania- and zirconia-based catalysts for esterification and transesterification has been previously reported. However, all of the previously cited work used high surface area, metal or metal oxide powders which are unsuited for packing in a continuous flow reactor. There have been no reports describing the use of modified spherical porous zirconia microspheres in a fixed bed reactor operated at high temperature and pressure in a fixed bed reactor, as we propose in this Phase I feasibility research. Our approach will differ significantly from all prior work by drawing upon our extensive expertise in the production of thermally and chemically stable porous transition metal oxide (zirconia) microspheres that can be used to produce a continuous flow reactor. The catalytic materials we propose to use will have a well defined pore structure and be stable under both high pressure and high temperature conditions. A careful survey of the current scientific literature and published patents reveals that the approach we propose to study in Phase I, specifically the use of spherical porous microspheres of modified and unmodified zirconia that can withstand high temperature and pressure conditions as fixed bed catalysts for biodiesel production, has not been reported before. We anticipate demonstrating the feasibility of using these mechanically and thermally stable catalysts for the continuous production of biodiesel that can meet the accepted ASTM fuel standards and justify scale up to large-scale biodiesel production in Phase II research. The main Phase I research objectives will be four-fold: 1. Test the feasibility of using porous zirconia microspheres (with and without acid or base pre-use modification) for continuous fixed-bed production of biodiesel from refined and used lipid feedstocks. 2. Explore the effect of temperature and pressure upon production rate and byproduct formation. 3. Optimize the production parameters of biodiesel to meet ASTM specifications while maintaining high production rates using the newly developed fixed-bed continuous flow reactor. 4. Demonstrate the feasibility of regenerating a zirconia-based catalyst to its original activity after the fixed-bed reactor has been used purposely fouled. APPROACH: Production and purchase of substrate porous zirconia particles: At the beginning of the project, porous zirconia particles will be prepared as a single large batch of porous zirconia particles that will be used for all subsequent studies. The use of a single batch of substrate zirconia will allow for the direct comparison of data obtained from different surface modifications and eliminate any variations due to the substrate particles. Surface modification of zirconia particles to produce base and acid modified surfaces: The preparation of acid and base modified porous zirconia catalysts will be performed using published methods of synthesis. Packing of modified zirconia particles into high pressure and temperature stable flow reactors: Different porous zirconia-based reactors will be produced by packing the particles into all-stainless steel column hardware outfitted with stainless steel frits. The particles will be packed into stainless steel high performance liquid chromatographic column hardware using a downward slurried method. When the pressure has been fully released, the column will be disconnected from the apparatus and the frit and end fitting will be attached to the inlet to complete construction of the reactors. Initial testing of modified zirconia particles: Initially the different types of zirconia catalyst will be evaluated to see if they show a potential for the transesterification of triglycerides to the fatty acid methyl esters under initial testing conditions. The purpose of these initial experiments is to determine feasibility and select the most promising materials for further optimization of reactor conditions with the ultimate goal of selecting the best material and determining conditions to produce biodiesel fuel that meets or exceeds the ASTM standards for biodiesel (B100) fuel. Initial testing of the catalysts will be performed using refined soybean oil and methanol. Use of optimized conditions for biodiesel production from different feedstock lipids: After the optimized conditions have been determined for each catalyst, different feedstocks will be tested (both crude and refined stocks). Biodiesel production under each condition will be analyzed and glycerol production will be monitored. Regeneration of reactor catalyst and report preparation: An important goal of this project will be to demonstrate that the zirconia-based catalyst can be regenerated to its original performance after it has been purposefully fouled with dirty feedstock lipids and performance has likely decreased from its original production efficiency. A significant advantage of using a zirconia-based catalyst is that it is chemically and thermally stable so very aggressive cleaning conditions may be used without degradation of the porous particles
