Biodiesel from alligator fat using supercritical methanol via a laboratory scale flow reactor August Gallo Thomas Junk University of Louisiana at Lafayette Department of Chemistry UNIVERSITY OF LOUISIANA AT LAFAYETTE RAY P. AUTHEMENT COLLEGE OF SCIENCES DEPARTMENT OF CHEMISTRY

Fossil fuels  According to the Energy Information Administration (EIA), the world energy consumption is projected to increase by 33% from 2007 to 2035  In the year 2007 the United States alone consumed 21% of the world’s energy  As of 2008, transportation share of the U.S. petroleum consumption is 71%  The U.S transportation sector is 97 percent reliant on oil, with 60 percent of this oil imported

Biofuels  Energy security  Economic stability  Environmental gains  Dominant biofuels- biodiesel and bioethanol.  Food vs. biofuels

Alligator and its fats  In United States, Louisiana has the population of about 1.5 million alligators constituting 75% of the total population  Louisiana’s wild and farm raised alligator harvest is approximately 275,000 per year  In the year 2008 the revenue generated from wild and farm raised alligators was ~ $70 million  15 million pounds of alligator fat is available annually in Louisiana, which is currently being disposed as waste The increasing popularity of alligator farming, coupled with the high fat content of alligators, strongly supports the use of waste alligator fat as a source for biodiesel fuel. It stands to reason, however, that the methods presented here are of general applicability for the conversion of other animal fats (e.g., lard, chicken fat) to biodiesel.

Current status Biodiesel is increasingly used as a renewable alternative to conventional diesel fuel. With approximately 51 billion liters in 2010, the United States is the largest producer of biofuels. Biodiesel is prepared from vegetable or animal fats, usually by transesterification with methanol (Fig. 1)

An established procedure for the transesterification of fats with methanol consists of stirring the respective fat with methanol and a suitable catalyst, usually sodium hydroxide. An alternative procedure is the rendering of oil prior to transesterification, leaving a residue of nitrogen-rich material. In each case, solid byproducts and an emulsion are obtained, which have to be separated by filtration and/or centrifugation and generate a significant amount of caustic solid waste. A typical setup is shown in Fig. 2, the formation of solids in the product mixture is evident by the turbid appearance of the fluid phase. Optimized conditions consisted of heating the fat with methanol in a 3:1 weight ratio for 2.5 hours at 65°C in the presence of 1% of NaOH. Traditional processing

Production of biodiesel Fig. 2

Conversion using supercritical methanol - rationale We are developing an alternative procedure with several objectives in mind: 1) the reduction of elimination of solid waste products, 2) the avoidance of emulsions and caustic residues that require additional separation steps, and 3) reduced reaction times. The use of supercritical methanol eliminates the need for a catalyst, promises short reaction times, and produces product mixtures that are virtually free of solid residues. Methanol has a critical temperature of approx. 240°C, as shown in the diagram below (Fig. 3)

Batch Process Equipment

Fatty acid profile of alligator fat Fatty acids 1:4 MR 2 h % area (LSU) 1:4 MR 2 h % area (ULL) C14: C15: C16: C16: C17: C18: C18: C18: C18: C20: C20: C20: C21: Fatty acids 1:4 MR 2 h % area (LSU) 1:4 MR 2 h % area (ULL) Unsaturated Saturated

GC analysis Main methyl ester after treatment in flow reactor

Conclusions – Batch process The use of supercritical methanol in the conversion of waste alligator fat to biodiesel was shown to be a viable alternative to traditional transesterification. Key advantages of this method include: a) avoidance of caustic catalysts, b) the elimination of solid byproducts posing disposal problems, and c) significant simplification of the conversion process, no emulsions. The use of raw fat containing proteins resulted in the formation of liquid amines and amides in the resulting product. These pose no harm; in fact, the addition of amines to increase the thermal stability of diesel fuels has been patented (USP 4,166,726). Furthermore, it is common practice to co-inject solutions of urea into diesel engines to reduce harmful NOX emissions. Optimized batch conditions were achieved when 2 g of oil was heated with 8 g of methanol to 300°C for 3 hours, resulting in 95.8 % of methyl esters and undetectable levels of free acids.

Flow Reactor Study Several inherent problems with the batch process- temperature control after completion of the reaction. With a flow reactor, the reactants can enter and leave the system under more controlled conditions. A simple system was devised using an HPLC pump, shut off valve, woods metal bath, heater, digital thermometer, 6 ft. column, water cooled jacket and a pressure valve to control the pressure.

Flow Reactor

Flow Reactor Study-FAME analysis Concentration of the main methyl ester as a function of time, 1 mL/min

Flow Reactor Study-FAME analysis Concentration of the main methyl ester as a function of time, 0.2 mL/min

Flow Reactor Study-FAME analysis Concentration of the main methyl ester as a function of temperature - 1 mL/min

GC Analysis of FAME vs.Temperature

Conclusions – Flow Reactor  These graphs show the concentration of the esters increases exponentially.  The highest concentration was reached at 400°C for the all esters, then the concentrations decreased rapidly. For the higher flow rate the exponential decrease was not observed.  A new run was carried at 300, 320, 340, 360, 380, 400, 420, 440, 460, 480°C and 500°C. The number of samples was increased in order to have more information about the ester concentration especially between 400°C and 500°C.  These graphs show that the highest concentration was reached at 460°C. In this case we observed, for the unsaturated ester, a exponential decrease of the concentration.

Economic evaluation The economics of the lipid production was investigated with the following assumptions:  The cost of lipid source was assigned to be zero, since feed stock was alligator fat waste that normally entails disposal costs for the processing industry.  Byproduct glycerol was assumed to fetch a price of $ 0.22 per kg (ICIS, 2010).  Cost of equipment were taken from SuperPro Designer and from the equipment data of Peters and Timmerhaus (Peter and Timmerhaus, 1981).

Equipment cost Name of equipment No of equipments Total cost Grinder173,000 Electric heater263,000 Heat exchanger11000 Nutsche filter1240,000 Storage tank145,000 Vessel reactor2129,766.8 Distillation column121, Cooling heat exchanger Cooling heat exchanger Total cost

Utilities Name of equipmentUtilities ElectricityKW h/y Grinder650,240 Electric heater1,504,512 Vessel reactor Cooling water/steam Cooling water37547 m 3 /y Steam kg/y

Results (Economic analysis)  Fixed capital investment = 2.51 million dollars.  Total capital investment = 2.98 million dollars.  Raw material cost = 0.44 million dollars.  Labor cost (18 people) = 0.87 million dollars.  Utility costs = million dollars.  Annual total product cost = 3.01 million dollars.  Average return on investment = 28.5% per year.  Payback period = 2.3 years.

Acknowledgements I would like to thank the department of chemistry at UL Lafayette and the following individuals who made this work possible through support and guidance:  Dr. Rakesh Bajpai, Professor of Chemical Engineering, UL  Dean Mark Zappi, Dean of Engineering, UL  Patrick Spiller, UL  Kevin Martin, University of Poitiers, France  Teddy Lacourcelle, University of Poitiers, france  Dr. William Holmes, UL  Dr. Yuemin Liu, UL