EP2069465A2 - Procédés et appareil permettant de produire des esters d'alkyles à partir de matériaux de départ lipidiques et systèmes les utilisant - Google Patents

Procédés et appareil permettant de produire des esters d'alkyles à partir de matériaux de départ lipidiques et systèmes les utilisant

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Publication number
EP2069465A2
EP2069465A2 EP07840692A EP07840692A EP2069465A2 EP 2069465 A2 EP2069465 A2 EP 2069465A2 EP 07840692 A EP07840692 A EP 07840692A EP 07840692 A EP07840692 A EP 07840692A EP 2069465 A2 EP2069465 A2 EP 2069465A2
Authority
EP
European Patent Office
Prior art keywords
oil
reaction mixture
acid
catalyst
metal oxide
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP07840692A
Other languages
German (de)
English (en)
Inventor
Clayton V. Mcneff
Larry C. Mcneff
Arlin E. Gyberg
Bingwen Yan
Daniel Thomas Nowlan
Brian Krohn
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mcneff Research Consultants Inc
MCNEFF RES CONSULTANTS Inc
Original Assignee
Mcneff Research Consultants Inc
MCNEFF RES CONSULTANTS Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mcneff Research Consultants Inc, MCNEFF RES CONSULTANTS Inc filed Critical Mcneff Research Consultants Inc
Publication of EP2069465A2 publication Critical patent/EP2069465A2/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11C—FATTY ACIDS FROM FATS, OILS OR WAXES; CANDLES; FATS, OILS OR FATTY ACIDS BY CHEMICAL MODIFICATION OF FATS, OILS, OR FATTY ACIDS OBTAINED THEREFROM
    • C11C3/00—Fats, oils, or fatty acids by chemical modification of fats, oils, or fatty acids obtained therefrom
    • C11C3/003—Fats, oils, or fatty acids by chemical modification of fats, oils, or fatty acids obtained therefrom by esterification of fatty acids with alcohols
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C67/00—Preparation of carboxylic acid esters
    • C07C67/03—Preparation of carboxylic acid esters by reacting an ester group with a hydroxy group
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L1/00—Liquid carbonaceous fuels
    • C10L1/02—Liquid carbonaceous fuels essentially based on components consisting of carbon, hydrogen, and oxygen only
    • C10L1/026—Liquid carbonaceous fuels essentially based on components consisting of carbon, hydrogen, and oxygen only for compression ignition
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E50/00—Technologies for the production of fuel of non-fossil origin
    • Y02E50/10—Biofuels, e.g. bio-diesel

Definitions

  • the present invention relates to the production of alkyl esters from lipid feed stocks. More specifically, the present invention relates to methods and apparatus including metal oxide catalysts for producing alkyl esters from lipid feed stocks.
  • biodiesel refers to a diesel-equivalent, processed fuel derived from biological sources, such as vegetable oils and/or animal fats.
  • Biodiesel is a processed fuel that can be readily used in vehicles with diesel engines. Biodiesel can be used in pure form or may be blended with petroleum diesel at any concentration in most modern diesel engines.
  • the use of biodiesel offers many advantages. For example, it has been estimated that biodiesel reduces emissions of carbon monoxide (CO) by approximately 50% and carbon dioxide by 78% on a net lifecycle basis because the carbon in biodiesel emissions is recycled from carbon that was already in the atmosphere, rather than being fossil carbon from petroleum that was previously sequestered in the earth's crust.
  • CO carbon monoxide
  • biodiesel is generally biodegradable and non-toxic.
  • Biodiesel typically includes alkyl esters of fatty acids.
  • the alkyl group is commonly methyl, ethyl, propyl, or isopropyl, although it can also include higher numbers of carbon atoms.
  • Alkyl esters can be produced from fats or oils via catalyzed or uncatalyzed reactions. Catalyzed reactions for producing alkyl esters can be categorized as either homogeneous or heterogeneous catalyst reactions. The definition of homogeneous and heterogeneous is from the perspective of the catalyst. In a homogeneous reaction, the catalyst is completely dissolved in one of the feed stocks, such as the alcohol, whereas in a heterogeneous reaction the catalyst forms a mixture (it is not dissolved completely) with the total reaction mixture.
  • Reactions for producing biodiesel can specifically include: 1) direct base catalyzed transesterification of the oil or fat with an alcohol; 2) direct acid catalyzed transesterification of the oil or fat with an alcohol; and 3) initial conversion of the oil triglycerides to fatty acids and then to alkyl esters via acid catalyzed esterification.
  • the direct base catalyzed method is currently favored for industrial production of alkyl esters because the underlying reaction is generally faster than some other methods.
  • triglycerides from a fat or oil such as soybean oil
  • a short chain alcohol such as methanol or ethanol
  • the alkaline catalyst is usually sodium or potassium hydroxide that has been dissolved in the short chain alcohol.
  • the short chain alcohol is generally added in a molar excess (e.g., greater than 3: 1 of alcohol : triglyceride) to promote conversion of the lipid to biodiesel.
  • the direct base homogenous catalyzed method is commonly conducted in a batch processing mode where the reactants are mixed together in a batch, allowed to react and then the biodiesel is harvested from the resulting mixture.
  • the present invention relates to methods and apparatus for producing alkyl esters from lipid feed stocks, such as plant oils and/or animal fats, and systems including the same.
  • the invention includes a process for producing alkyl esters including mixing a lipid feed stock with an alcohol to form a reaction mixture, contacting the reaction mixture with a catalyst under supercritical conditions for the alcohol, the catalyst comprising an unmodified metal oxide selected from the group consisting of alumina, titania, zirconia, and hafnia, and removing residual free fatty acids from the reaction mixture.
  • the invention includes a process for producing alkyl esters including mixing a lipid feed stock with an alcohol to form a reaction mixture, contacting the reaction mixture with a catalyst under supercritical conditions for the alcohol, the catalyst comprising a metal oxide selected from the group consisting of alumina, titania, zirconia, and hafnia, wherein the metal oxide has been treated with a Br ⁇ nsted acid or a Br ⁇ nsted base, and removing residual free fatty acids from the reaction mixture.
  • the invention includes a process for producing alkyl esters via transesterification or esterification from a feed stock including mixing the feed stock with an alcohol to form a reaction mixture, the feed stock comprising a triglyceride or a carboxylic acid; and pumping the reaction mixture into a housing comprising a porous catalyst, the porous catalyst comprising an average particle size of about 0.2 microns to about 1 millimeter, the temperature and pressure within the housing comprising supercritical conditions for the alcohol, the porous catalyst comprising an unmodified metal oxide selected from the group consisting of alumina, titania, zirconia, and hafnia and collecting a reaction product from the housing, the reaction product comprising esters in an amount at least equal to 80 % of the triglyceride or carboxylic acid in the feed stock on a molar basis.
  • FIG. 1 is a schematic view of a method of producing alkyl esters in accordance with an embodiment of the invention.
  • FIG. 2 is a schematic view of a method of producing alkyl esters in accordance with another embodiment of the invention.
  • FIG. 3 is a schematic view of an alkyl ester production plant and method of producing alkyl esters in accordance with another embodiment of the invention.
  • FIG. 4 is a schematic view of a diesel power plant system in accordance with an embodiment of the invention.
  • FIG. 5 is a graph showing the percent conversion of soybean oil to fatty acid methyl esters using a phosphated zirconia catalyst.
  • FIG. 6 is a graph showing the percent conversion of soybean oil to fatty acid methyl esters versus flow rate through a reactor.
  • FIG. 7 is a graph showing the percent conversion of soybean oil to fatty acid methyl esters versus temperature.
  • FIG. 8 is a graph showing the percent conversion of soybean oil to fatty acid methyl esters using carbon-clad zirconia.
  • FIG. 9 is a graph showing the percent conversion of soybean oil to fatty acid methyl esters versus temperature for selected samples from Example 24.
  • FIGS. 1OA and 1OB are graphs showing the reaction temperature over time and the conversion percentage over time for Example 26.
  • alkyl esters can be produced from fats or oils via catalyzed or uncatalyzed reactions.
  • Catalyzed reactions for producing alkyl esters can be categorized as either homogeneous or heterogeneous reactions. In a homogeneous reaction, the catalyst is completely dissolved in one of the feed stocks, such as the alcohol, whereas in a heterogeneous reaction the catalyst is not dissolved.
  • homogenous catalysts are currently favored for the commercial production of alkyl ester compositions.
  • homogenous acid or base catalysts generally require a costly neutralization and fuel washing steps to extract the catalysts after the reaction, making those processes less economical and requiring the use of more water.
  • Heterogeneous catalysts offer various advantages including the ability to conduct transesterifications and esterifications simultaneously while simplifying later separation steps.
  • the method can include the use of methanol at supercritical conditions.
  • the thermodynamic critical point for methanol is a temperature of 512.6 degrees Kelvin and a pressure of 8.09 MPa (or 79.8 atm).
  • Many previous approaches for producing biodiesel fuel compositions include the use of temperature and pressure conditions that are substantially below supercritical conditions for alcohols such as methanol.
  • One reason for this includes the established view that processes requiring lower energy input are generally more economical. Another reason includes a concern for the possible uncontrolled further break down of reaction products into potentially undesirable byproducts.
  • reaction products from the transesterification of triglycerides include fatty acid alkyl esters and glycerol.
  • the amount of glycerol produced in many transesterification reactions depends on many factors including the precise compositions and quantities of the feed stocks used but can frequently be around 10% by mass. However, in some embodiments of the invention, the formation of higher value byproducts, such as dimethyl ether have been observed, which can then be captured and sold making the overall process more economically efficient.
  • the amount of glycerol produced can be reduced to less than about 10% by mass. In some embodiments of the invention the amount of glycerol produced can be reduced to less than about 5% by mass. In some embodiments of the invention the amount of glycerol produced can be reduced to about 1% or less by mass. It is believed that in such circumstances the glycerol from the reaction is further broken down into other byproducts.
  • Lipid feed stock costs are the single highest contributor to the overall cost of production of biodiesel fuel. As such, it is desirable to utilize inexpensive low value feed stocks.
  • low value feed stocks such as animal fats and waste cooking oils typically have high levels of free fatty acids, which cannot be converted to biodiesel using traditional base catalysis methods.
  • methods and catalysts of the invention operating at supercritical conditions are capable of both esterification and transesterification and can therefore be used to convert both free fatty acids and triglycerides from low value feed stocks into biodiesel resulting in a more economical biodiesel production cost.
  • Metal oxides used with embodiments of the invention can include metal oxides whose surfaces are dominated by Lewis acid-base chemistry.
  • a Lewis acid is an electron pair acceptor.
  • Metal oxides of the invention can have Lewis acid sites on their surface and can specifically include alumina, zirconia, titania and hafnia.
  • Metal oxides of the invention can also include silica clad with a metal oxide selected from the group consisting of zirconia, alumina, titania, hafnia, zinc oxide, copper oxide, magnesium oxide and iron oxide.
  • metal oxides can include yttria (yttrium oxide), such as ytrria stabilized zirconia.
  • metal oxides can include magnesium oxide and/or cerium dioxide.
  • Metal oxides of the invention can also include mixtures of metal oxides.
  • metal oxides of the invention can include mixtures including one or more of zirconia, alumina, titania and hafnia.
  • One issue associated with many previous methods for producing biodiesel is that the catalysts used are subject to poisoning over time. Specifically, many existing catalysts are affected by the reaction conditions (e.g., pH, temperature, pressure) in a manner so as to reduce reaction yield over time.
  • the reaction conditions e.g., pH, temperature, pressure
  • some embodiments of metal oxide catalysts as described herein are advantageous because they are highly resistant to poisoning over time. This is particularly significant in the context of supercritical reaction conditions, which may otherwise tend to promote catalyst poisoning.
  • zirconia, titania and hafnia offer particular advantages because they are very chemically and thermally stable and can withstand very high temperatures and pressures (such as supercritical conditions for various alcohols) as well as extremes in pH. Such catalysts can exhibit a resistance to poisoning over time.
  • the metal oxide catalyst can include zirconia, titania, and/or hafnia. Zirconia and hafnia are even more thermally stable than titania.
  • the metal oxide catalyst can include zirconia and/or hafnia.
  • Some feed stocks may include components, such as lecithin, that can lead to the deposit of residues resulting in clogging and/or obstruction of a transesterification reactor.
  • the significant thermal stability of metal oxides used with embodiments of the invention can be advantageous in this context because the reactor can be cleaned out through the use of an oxygen containing gas or liquid at extremely high temperatures to combust any residue that has been deposited on the metal oxide catalyst, thereby cleaning the reactor and returning it to its original state.
  • Other types of catalysts may not have sufficient thermal stability to perform such a cleaning/regeneration process.
  • the metal oxides used with embodiments of the invention can be bare or unmodified.
  • unmodified metal oxide shall refer to a metal oxide that includes substantially only the metal oxide at its surface, and thus does not include significant concentrations of chemical groups such as phosphates or sulfates on its surface.
  • Many conventional catalyst materials include various modifying groups to enhance catalysis.
  • unmodified metal oxides can surprisingly be used to achieve high conversion percentages and relatively small residence times.
  • metal oxides of the invention can be modified with another compound.
  • the Lewis acid sites on metal oxides of the invention can interact with Lewis basic compounds.
  • metal oxides of the invention can be modified by adsorbing Lewis basic compounds to the surface of metal oxides of the invention.
  • a Lewis base is an electron pair donor.
  • Lewis basic compounds of the invention can include anions formed from the dissociation of acids such as hydrobromic acid, hydrochloric acid, hydroiodic acid, nitric acid, sulfuric acid, perchloric acid, boric acid, chloric acid, phosphoric acid, pyrophosphoric acid, methanethiol, chromic acid, permanganic acid, phytic acid and ethylenediamine tetramethyl phosphonic acid (EDTPA).
  • acids such as hydrobromic acid, hydrochloric acid, hydroiodic acid, nitric acid, sulfuric acid, perchloric acid, boric acid, chloric acid, phosphoric acid, pyrophosphoric acid, methanethiol, chromic acid, permanganic acid, phytic acid and ethylenediamine tetramethyl phosphonic acid (EDTPA).
  • acids such as hydrobromic acid, hydrochloric acid, hydroiodic acid, nitric acid, sulfuric acid, perchloric acid, bo
  • Lewis basic compounds of the invention can also include hydroxide ion as formed from the dissociation of bases such as sodium hydroxide, potassium hydroxide, lithium hydroxide and the like.
  • Metal oxides of the invention can include metal oxide particles clad with carbon.
  • Carbon clad metal oxide particles can be made using various techniques such as the procedures described in U.S. Pat. Nos. 5,108,597, 5,254,262, 5,346,619, 5,271,833, and 5,182,016, the contents of which are herein incorporated by reference.
  • Carbon cladding on metal oxide particles can render the surface of the particles more hydrophobic.
  • Metal oxides of the invention can also include polymer coated metal oxides.
  • metal oxides of the invention can include a metal oxide coated with polybutadiene (PBD).
  • PBD polybutadiene
  • Polymer coated metal oxide particles can be made using various techniques such as the procedure described in Example 1 of U.S. Pub. Pat. App. No. 2005/0118409, the content of which is herein incorporated by reference. Polymer coatings on metal oxide particles can render the surface of the particles more hydrophobic.
  • Metal oxide catalysts of the invention can be made in various ways.
  • a colloidal dispersion of zirconium dioxide can be spray dried to produce aggregated zirconium dioxide particles.
  • Colloidal dispersions of zirconium dioxide are commercially available from Nyacol Nano Technologies, Inc., Ashland, MA.
  • the average diameter of particles produced using a spray drying technique can be varied by changing the spray drying conditions. Examples of spray drying techniques are described in U.S. Pat. No. 4,138,336 and U.S. Pat. No. 5,108,597, the contents of both are herein incorporated by reference. It will be appreciated that other methods can also be used to create metal oxide particles.
  • Metal oxide particles used in embodiments of the invention can be sintered by heating them in a furnace or other heating device at a relatively high temperature.
  • the particles are sintered at a temperature of 160° C or greater.
  • the particles are sintered at a temperature of 400° C or greater.
  • the particles are sintered at a temperature of 600° C or greater.
  • Sintering can be done for various amounts of time depending on the desired effect. Sintering can make the aggregated particles more durable.
  • the particles are sintered for more than about 30 minutes.
  • the particles are sintered for more than about 3 hours. However, sintering also reduces the surface area.
  • the particles are sintered for less than about 1 week.
  • particles within a desired size range can be selected for use as a catalyst.
  • particles can be sorted by size such as by air classification, elutriation, settling fractionation, or mechanical screening.
  • the size of the particles is greater than about 0.2 microns. In some embodiments, the size of the particles is greater than about 0.25 ⁇ m. In some embodiments the size range selected is from about 0.2 microns to about 1 mm. In some embodiments the size range selected is from about 1 ⁇ m to about 100 ⁇ m. In some embodiments the size range selected is from about 5 ⁇ m to about 15 ⁇ m. In some embodiments the size of the particles is about 80 ⁇ m. In some embodiments the size of the particles is about 25-35 ⁇ m. In some embodiments the size of the particles is about 5 ⁇ m.
  • the particles can be spherical or irregular in shape.
  • metal oxide particles used with embodiments of the invention are porous.
  • the metal oxide particles can have an average pore size of about 30 angstroms to about 2000 angstroms.
  • metal oxide particles used are non- porous.
  • the anion of an acid can be adhered to a particle by refluxing particles in an acid solution.
  • the particles can be refluxed in a solution of sulfuric acid.
  • the anion formed from dissociation of a base such as the hydroxide ion formed from dissociation of sodium hydroxide
  • the particles can be adhered to a particle by refluxing particles in a base solution.
  • the particles can be refluxed in a solution of sodium hydroxide.
  • the base or acid modification can also be achieved under exposure to the acid or base in either batch or continuous flow conditions when disposed in a reactor housing at elevated temperature and pressure to speed up the adsorption/modification process.
  • fluoride ion such as formed by the dissociation of sodium fluoride, can be adhered to the particles.
  • Metal oxide particles used in embodiments of the invention can be packed into a housing, such as a column.
  • the metal oxide particles disposed in a housing can form a fixed bed reactor. Disposing the metal oxide particles in a housing can offer the advantage of facilitating continuous flow processes.
  • Many different techniques may be used for packing the metal oxide particles into a housing. The specific technique used may depend on factors such as the average particle size, the type of housing used, etc. Generally speaking, particles with an average size of about 1-20 microns can be packed under pressure and particles with an average size larger than 20 microns can be packed by dry-packing/tapping methods or by low pressure slurry packing.
  • the metal oxide particles of the invention can be impregnated into a membrane, such as a PTFE membrane.
  • a lipid feed stock 102 is held in a first reservoir.
  • the lipid feed stock 102 can include various types of plant oils and animal fats as described more fully below.
  • the first reservoir can optionally include an agitation mechanism and temperature control to keep the components in the first reservoir thoroughly mixed.
  • An alcohol feed stock 104 is held in a second reservoir.
  • the alcohol feed stock 104 can include one or more types of alcohol as described more fully below.
  • the feed stocks can be processed in order to remove particulate matter and other debris before being processed through the reactor.
  • the feed stocks can be filtered or distilled.
  • the feed stocks can be processed with a continuous centrifuge that can spin out all particulates and in some cases water from the lipid feed stock.
  • a feed stock gas sparger/bubbler can be added to the system in order to displace dissolved oxygen to avoid any oxidation reactions that can potentially occur at high temperatures.
  • the feed stocks can be sparged with nitrogen gas in order to further limit potential oxidation reactions.
  • the biological lipid feed stock and the alcohol feed stock are then mixed to form a reaction mixture 106.
  • Mixing may be done in a separate mixing vessel or it may be done by simply injecting one feed stock into the other.
  • the amount of alcohol supplied is in a molar excess to the stoichiometric ratio of the reaction.
  • the stoichiometric ratio is 3 moles of alcohol for every 1 mole of triglyceride.
  • the reaction can be pushed farther towards completion by adding a molar excess of alcohol.
  • an amount of alcohol is added to the reaction mixture that exceeds the ratio of 3 parts alcohol to 1 part triglyceride.
  • the alcohol is added to the reaction mixture in a less than stoichiometric ratio.
  • the reaction mixture can have a ratio of 1-3 moles of alcohol to 1 mole of triglyceride.
  • the reaction mixture can also include a carrier compound.
  • a carrier compound can serve various purposes including helping to reduce the viscosity of the reaction mixture.
  • the carrier compound can be a compound that is non-reactive under the reaction conditions. Examples of carrier compounds can include, but are not limited to, hexane, saturated cycloalkanes, and fluorinated hydrocarbons. Carrier compounds can be present in the reaction mixture in an amount from 0.0 wt. % to 99.9 wt. %. Conversely, active components, such as the lipid feed stock and the alcohol feed stock can be present in the reaction mixture in an amount from 0.1 wt. % to 100.0 wt. %.
  • the reaction mixture can also include various types of additives.
  • the reaction mixture can include an additive that is converted by a chemical reaction into a compound that has a scent.
  • esters are responsible for common scents, such as fruit scents.
  • ethyl (S)-(+)-2-methylbutanoate is known to have a fruity, apple-like scent.
  • metal oxides used in embodiments of the invention can catalyze the conversion of carboxylic acids to esters, in some embodiments a carboxylic acid can be added to the reaction mixture and can then be converted into an ester that imparts a distinct scent to the resulting alkyl ester product composition.
  • a scent can be used to enhance the distinctiveness of the resulting product, such as a biodiesel product, while still allowing for the resulting biodiesel to meet ASTM testing standards.
  • Those compounds with carboxylic acid groups that can be converted into scented esters upon esterification can be referred to as "scent precursor compounds".
  • the reaction mixture can include one or more scent precursor compounds.
  • salicylic acid can be added to the reaction mixture and will result in the production of methyl salicylate (if methanol is used as the alcohol feed stock), which has a strong wintergreen scent.
  • the reaction mixture can then be contacted with a metal oxide catalyst 108.
  • the metal oxide catalyst can have an acid or base adsorbed thereto. In some embodiments, the metal oxide is unmodified and does not have an acid or base adsorbed thereto.
  • the metal oxide catalyst can be disposed within a housing. By way of example, the metal oxide catalyst can be within a column. The metal oxide catalyst can be packed within the housing such that the reaction mixture must pass between particles of the metal oxide catalyst as it passes through the housing.
  • a pre-heating step is performed to raise the temperature of the reactants before they enter a housing containing the metal oxide catalyst.
  • Preheating of the reactants can be performed in various ways including using a heating block, a heating bath, a counter-current heat exchanger, etc. While not intending to be bound by theory, it is believed that pre-heating the reactants can improve the efficiency of the reaction in part because of the effect pre-heating has on the maintenance of temperatures within the housing.
  • the invention includes preheating the reactants to at least about 70% of the reaction temperature inside of the housing containing the metal oxide catalyst. In some embodiments, the invention includes preheating the reactants to at least about 80% of the reaction temperature inside of the housing containing the metal oxide catalyst.
  • the invention includes preheating the reactants to at least about 90% of the reaction temperature inside of the housing containing the metal oxide catalyst. In some embodiments, the invention includes preheating the reactants to at least about 95% of the reaction temperature inside of the housing containing the metal oxide catalyst. In some embodiments, the invention includes preheating the reactants to substantially the same temperature as the reaction temperature inside of the housing containing the metal oxide catalyst. In some embodiments, the invention includes preheating the reactants to a temperature higher than the reaction temperature inside of the housing containing the metal oxide catalyst. In some cases, the reactants are raised to supercritical conditions before entering the inside of the reactor housing. In many embodiments, the reaction mixture is maintained at an elevated temperature within the reactor housing.
  • the housing can be configured to withstand the temperature and pressure under which the reaction mixture is kept.
  • a heating element is in thermal communication with the housing so as to be able to heat the reaction mixture up to the desired temperature. If the temperature of the reaction mixture is not sufficiently high, the reaction may proceed more slowly than desired.
  • the temperature of the reaction mixture is about 50° Celsius or hotter. In some embodiments, the temperature of the reaction mixture is about 100° Celsius or hotter. In some embodiments, the temperature of the reaction mixture is about 150° Celsius or hotter. In some embodiments, the temperature of the reaction mixture is about 200° Celsius or hotter. In some embodiments, the temperature of the reaction mixture is about 300° Celsius or hotter. In some embodiments, the temperature of the reaction mixture is about 350° Celsius or hotter. In some embodiments, the temperature of the reaction mixture is greater than the critical temperature of the alcohol used as a reaction feed stock.
  • the temperature of the reaction mixture is less than about 500° Celsius. In some embodiments, the temperature of the reaction mixture is less than about 400° Celsius. In some embodiments, the temperature of the reaction mixture inside the reactor is between about 350 ° Celsius and about 400° Celsius.
  • the reaction mixture 106 is kept under pressure.
  • the housing can be configured to withstand the pressure under which the reaction mixture is kept.
  • a desirable pressure for the reaction mixture 106 can be estimated with the aid of the Clausius-Clapeyron equation.
  • the Clausius- Clapeyron equation can be used to estimate the vapor pressures of a liquid.
  • the Clausius-Clapeyron equation is as follows:
  • ⁇ H vap is the enthalpy of vaporization
  • Pi is the vapor pressure of a liquid at temperature T 1
  • P 2 is the vapor pressure of a liquid at temperature T 2
  • R is the ideal gas law constant.
  • the pressure inside the housing is greater than the vapor pressures of any of the components of the reaction mixture.
  • the pressure is greater than about 500 psi.
  • the pressure is greater than about 800 psi.
  • the pressure is greater than about 1000 psi.
  • the pressure is greater than about 1500 psi.
  • the pressure is greater than about 2000 psi.
  • the pressure is greater than about 3000 psi.
  • the pressure is greater than about 3000 psi. In an embodiment, the pressure is greater than about 4000 psi. In some embodiments, the pressure is between about 1500 psi and about 5000 psi. In some embodiments, the pressure inside the housing is greater than the critical pressure of the alcohol used in the reaction.
  • the reaction mixture may be passed over the metal oxide catalyst for a length of time sufficient for the reaction to reach a desired level of completion. This will in turn depend on various factors including the temperature of the reaction, the chemical nature of the catalyst, the surface area of the catalyst, and the like.
  • the term "residence time" can be used to describe the amount of time in which the reaction product mixture interacts with the catalyst in the reactor.
  • Embodiments of the invention can include methods and systems wherein the residence time is relatively small while still achieving high percentages of conversion.
  • the residence time is less than about 60 seconds. In some embodiment, the residence time is less than about 30 seconds. In some embodiment, the residence time is less than about 10 seconds.
  • reaction produces glycerol as a byproduct and the glycerol can be separated from the alkyl esters.
  • glycerol has a tendency to phase separate from alkyl esters and thus the separation process is relatively straightforward.
  • separation devices can be used such a centrifugal fluid separator or the like.
  • the bio-diesel fuel can then be stored in a storage tank or it can be immediately delivered to a diesel engine for use.
  • the glycerol or other reaction products can be stored and later sold or used as a feed stock for other chemical processes or as a feedstuff for animals or for human foods after further purification methods are used.
  • the method may optionally include a step of removing free fatty acids from the reaction mixture 111.
  • This step of removing free fatty acids can also be referred to as a "polishing" step. This can be performed at various points in the production process such as before or after the step of separating reaction product 110 and/or before or after passing the reaction mixture over the catalyst.
  • removing residual free fatty acids from the reaction mixture can include adding a compound to the reaction mixture that serves to react with the residual free fatty acids.
  • a compound can be referred to as a residual free fatty acid scavenger or scavenging compound.
  • An exemplary scavenging compound for this purpose is dimethyl carbonate.
  • other compounds can also be used as a scavenging compound.
  • the scavenging compound can be added to the reaction mixture before contacting the reaction mixture with the catalyst. In other embodiments, the scavenging compound can be added after the transesterification reaction has taken place.
  • the residual free fatty acids in the reaction mixture can be removed in other ways.
  • a material can be used to absorb residual free fatty acids compounds.
  • metal oxide media containing acid/base surface properties such as Lewis acid sites, Bronsted base sites, and/or Bronsted acid sites can be used to selectively bind, at relatively low temperatures, and remove organic acids from fatty acid alkyl ester reaction products. This can be performed in various ways.
  • an appropriate metal oxide media can be disposed within the interior volume of a housing. A crude reaction product mixture containing free fatty acids can then be pumped into the housing. After contacting the metal oxide media, free fatty acids in the crude reaction product mixture can be bound to the metal oxide media.
  • the purified reaction product mixture can be separated out, leaving behind the metal oxide media and bound organic acids.
  • the reaction can be performed under conditions sufficient to result in the production of aldehydes and/or ethers as a decomposition byproduct of glycerol instead of glycerol itself.
  • the reaction products include gases, such as dimethyl ether. While not intending to be bound by theory, the production of gases as a byproduct can be advantageous because it is believed to be easier to separate various gases from fatty acid alkyl esters than it is to separate out glycerol from fatty acid alkyl esters.
  • the catalyst can be periodically retreated with an acid (such as sulfuric acid or phosphoric acid) or a base (such as sodium hydroxide).
  • an acid such as sulfuric acid or phosphoric acid
  • a base such as sodium hydroxide
  • at least two different reactors are included in a production system such that feed stock flow can be diverted back and forth between the reactors so that one can be taken "off-line” and recharged without interrupting the production process.
  • heat from the effluent products is used to heat up the biological lipid feed stock and/or alcohol feed stock through a counter- flow heat exchanger.
  • An exemplary counter- flow heat exchanger is described in USPN 6,666,074, the contents of which are herein incorporated by reference.
  • a pipe or tube containing the effluent flow is routed past a pipe or tube holding the feed stock flow or the reaction mixture.
  • a pipe-in-pipe counter-flow heat exchanger can be used.
  • a thermally conductive material such as a metal, connects the effluent flow with the feed stock flow so that heat can be efficiently transferred from the effluent products to the feed stocks or the reaction mixture. Transferring heat from the effluent flow to the feed stock flow can make the alkyl ester production process more energy efficient since less energy is used to get the reaction mixture up to the desired temperature and promotes the mixing of the reactants for faster conversion within the continuous reactor.
  • the reactor housing is a ceramic that can withstand elevated temperatures and pressures.
  • the reactor housing is a metal or an alloy of metals such as INCONEL or HASTELLOY.
  • the reaction mixture reaches the desired level of reaction completion after one pass over the metal oxide catalyst bed or packing.
  • the effluent flow may be rerouted over the same metal oxide catalyst or routed over another metal oxide catalyst bed or packing so that reaction is pushed farther toward completion in measured stages.
  • two or more metal oxide catalyst beds can be used to convert lipid feed stocks to alkyl esters.
  • a reaction mixture can be passed through both an acid-modified metal oxide catalyst bed and a base-modified metal oxide catalyst bed in succession.
  • the reaction temperatures within each catalyst bed can be either the same or different.
  • a reaction mixture is first passed through an acid-modified metal oxide catalyst bed at a relatively lower temperature and then passed through a base-modified metal oxide catalyst bed at a relatively higher temperature.
  • the acid- modified catalyst reaction step can serve to reduce the amount of free fatty acids in the reaction mixture before it is passed on to the base-modified catalyst reaction step.
  • an acid-modified metal oxide catalyst such as sulfuric or phosphoric acid modified
  • a base-modified metal oxide catalyst such as sodium hydroxide modified
  • the reaction mixture passing through the reactor housing can be simultaneously exposed to both the acid and base modified metal oxide catalysts.
  • two different metal oxides such zirconia and titania
  • the reaction mixture passing through the reactor housing can be simultaneously exposed to both metal oxide catalysts.
  • the process shown in FIG. 1 can be conducted in a continuous flow mode.
  • the process can be carried out such that all of the steps are taking place simultaneously and feed stocks are continuously being turned into biodiesel fuel.
  • continuous flow production of biodiesel fuel can offer substantial advantages over batch production, including being more economical.
  • the flow may be periodically stopped to allow for the reaction to proceed to completion and then turned back on to continue the production cycle. This process of stopping and restarting flow can be referred to as a semi-continuous flow mode.
  • Feed stock materials (such as a lipid feed stock and an alcohol) can be stored in tanks before being used 112. The tanks can be heated or unheated. The feed stock materials are then pumped at a high pressure 114. The high pressure can be sufficient to prevent vaporization of the feed stock materials at the temperature of the reaction. Next, the feed stock materials are reacted in order to produce a reaction product composition that can include alkyl esters (such as biodiesel fuel) and byproducts (such as volatile materials and glycerol) 116.
  • alkyl esters such as biodiesel fuel
  • byproducts such as volatile materials and glycerol
  • reaction product composition 118 volatile materials (such as left over alcohol or other organic compounds) and byproduct gases are removed from the reaction product composition 118.
  • volatile materials such as left over alcohol or other organic compounds
  • byproduct gases are removed from the reaction product composition 118.
  • remaining byproducts such as glycerol
  • alkyl esters such as biodiesel fuel
  • end products such as alkyl esters and byproducts such as glycerol are stored until being used in other processes or until being shipped away from the production plant 122.
  • a lipid feed stock is held in a heated tank 124.
  • the heated tank 124 maintains the lipid feed stock at a temperature high enough to keep the lipid feed stock in a liquid state.
  • the lipid feed stock then passes through a lipid pump 126 before passing through a heat exchanger 132 where it absorbs heat from downstream products.
  • An alcohol feed stock is held in an alcohol tank 128.
  • the alcohol feed stock then passes through an alcohol pump 130 before passing through a heat exchanger 132 where it too absorbs heat from downstream products.
  • Both the alcohol and lipid source tanks may be continuously sparged with an inert gas such as nitrogen to remove dissolved oxygen from the feed stocks.
  • the lipid feed stock passes through a shutoff valve 134 and a filter 136 to remove particulate material of a certain size from the feed stock.
  • the alcohol feed stock also passes through a shutoff valve 138 and a filter 140.
  • Both the lipid feed stock and the alcohol feed stock then pass through a preheater 142 where they are mixed together to form a reaction mixture.
  • the preheater 142 can elevate the temperature of the reaction mixture to a desired level. Many different types of heaters are known in the art and can be used.
  • the reaction mixture can then pass through a reactor 144 where the lipids and alcohol are converted into alkyl esters forming a reaction product mixture.
  • the reactor can include a metal oxide catalyst.
  • the reactor can include an acid (such as sulfuric acid or phosphoric acid) modified or base (such as sodium hydroxide) modified metal oxide catalyst, or an unmodified metal oxide catalyst.
  • the reaction product mixture can pass through a backpressure regulator 146 and the heat exchanger 132 before passing on to a distillation apparatus 148.
  • the distillation apparatus 148 can be configured to carry out fractional distillation in order to remove excess alcohol from the reaction product mixture and/or isolate a fraction of the biodiesel fuel that meets ASTM specifications.
  • the fractional distillation apparatus can include any desired number of theoretical plates in order to recover a desired amount of the excess alcohol and to remove any other byproducts of the reaction.
  • the recovered alcohol can be de-watered by using molecular sieves.
  • the recovered alcohol can be put back into the alcohol tank 128 for reuse.
  • the remaining reaction products can then pass on to a stirred tank 150 where, in some embodiments, the remaining reaction products are mixed with a base solution, such as a sodium hydroxide solution, from a base solution tank 152.
  • the base solution can react with remaining free fatty acids in order to convert them (saponification) into a soap composition.
  • the residual free fatty acids are removed using other methods such as those described with respect to FIG. 1 above.
  • the remaining reaction products and the soap composition can then pass on to a separation apparatus 154 that is configured to separate byproducts such as glycerol and the soap composition from the alkyl esters (such as biodiesel).
  • the alkyl esters are then passed into an alkyl ester storage tank 156.
  • the soap composition and the glycerol are then passed into a byproduct tank 158.
  • a metal oxide can be used as a scrubber to reduce or eliminate certain components from a reaction mixture or feed stock.
  • unmodified zirconia, titania, and/or hafnia can be used to remove free fatty acids from compositions before or after the reaction that produces fatty acid methyl esters. It is believed that free fatty acids can be adsorbed to such metal oxides and therefore removed from the reaction mixture or reaction products.
  • biodiesel fuel is that it can be used to operate existing diesel engines.
  • the proper performance of diesel engines depends on a degree of consistency in the diesel fuel itself.
  • various factors can affect the consistency of the fuel made by transesterification including the specific feed stocks used, the particular separation steps used, and the type of catalysis used.
  • ASTM ASTM
  • ASTM D675 l-06a ASTM D675 l-06a
  • Embodiments of the invention can be used to produce a mixture of alkyl esters that meets the specifications of ASTM D6751-06a.
  • embodiments of the invention can include alkyl ester solutions complying with ASTM D6751-06a.
  • Embodiments can also include a diesel fuel composition including fatty acid alkyl esters as the reaction product of an alcohol and biological lipid feed stock including triglycerides, wherein at least about 70% of the triglycerides on a molar basis are converted into fatty acid methyl esters. In some embodiments, at least about 80% of the triglycerides on a molar basis are converted into fatty acid methyl esters. In some embodiments, at least about 90% of the triglycerides on a molar basis are converted into fatty acid methyl esters. In some embodiments, at least about 95% of the triglycerides on a molar basis are converted into fatty acid methyl esters.
  • Lipid feed stocks used in embodiments of the invention can be derived from many different sources.
  • lipid feed stocks used in embodiments of the invention can include biological lipid feed stocks.
  • Biological lipid feed stocks can include lipids (fats or oils) produced by any type of microorganism, plant or animal.
  • the biological lipid feed stocks used include triglycerides. Many different biological lipid feed stocks derived from plants can be used.
  • plant-based lipid feed stocks can include rapeseed oil, soybean oil (including degummed soybean oil), canola oil, cottonseed oil, grape seed oil, mustard seed oil, corn oil, linseed oil, safflower oil, sunflower oil, poppy-seed oil, pecan oil, walnut oil, oat oil, peanut oil, rice bran oil, camellia oil, castor oil, and olive oil, palm oil, coconut oil, rice oil, algae oil, seaweed oil, Chinese Tallow tree oil.
  • soybean oil including degummed soybean oil
  • canola oil cottonseed oil, grape seed oil
  • mustard seed oil corn oil
  • linseed oil safflower oil
  • sunflower oil poppy-seed oil
  • pecan oil walnut oil, oat oil, peanut oil, rice bran oil, camellia oil, castor oil
  • olive oil palm oil, coconut oil, rice oil, algae oil, seaweed oil, Chinese Tallow tree oil.
  • plant-based biological lipid feed stocks can be obtained from argan, avocado, babassu palm, balanites, borneo tallow nut, brazil nut, calendula, camelina, caryocar, cashew nut, Chinese vegetable tallow, cocoa, coffee, cohune palm, coriander, cucurbitaceae, euphorbia, hemp, illipe, jatropha, jojoba, kenaf, kusum, macadamia nuts, mango seed, noog abyssinia, nutmeg, opium poppy, perilla, pili nut, pumpkin seed, rice bran, sacha inche, seje, sesame, shea nut, teased, allanblackia, almond, chaulmoogra, cuphea, jatropa curgas, karanja seed, neem, papaya, tonka bean, tung, and ucuuba, cajuput, clausena
  • animal-based biological lipid feed stocks can include choice white grease, lard (pork fat), tallow (beef fat), fish oil, and poultry fat.
  • microbe-based lipid feed stocks can include the L-glycerol lipids of Archaea and algae and diatom oils.
  • lipid feed stocks derived from both plant and animal sources can be used such as yellow grease, white grease, and brown grease.
  • yellow, white or brown grease can include frying oils from deep fryers and can thus include fats of both plant and animal origin.
  • Lipid feed stocks can specifically include used cooking oil.
  • Brown grease also known as trap grease
  • lipid feed stocks used in embodiments of the invention can include non-biological lipid feed stocks.
  • Lipid feed stocks of the invention can include black oil.
  • lipid feed stocks can be derived from microorganisms such as bacteria, protozoa, algae, and fungi.
  • Lipid feed stocks of the invention can also include soap stock and acidulated soap stock.
  • Lipid feed stocks used with embodiments of the invention can specifically include low value feed stocks.
  • Low value feed stocks such as various types of animals fats and waste oils, generally have a relatively high concentration of free fatty acids.
  • One method of assessing the concentration of free fatty acids is to determine the acid number (or acid value) of the feed stock.
  • the acid number is the mass of potassium hydroxide (KOH) in milligrams that is required to neutralize one gram of the chemical substance being assessed.
  • KOH potassium hydroxide
  • the precise acid number as measured can vary because of the heterogeneity of the lipid feed stock.
  • a high value feed stock such as virgin soybean oil can have an acid number of about 0.35 whereas a lower value feed stock such as swine tallow can have an acid number of about 5.
  • Yellow grease, a low value feed stock can have an acid number of about 15 while acidulated soap stock, also a low value feed stock, can have an acid number of about 88 or higher.
  • the lipid feed stock used has an acid number of about 3 (mg KOH/g oil) or greater. In some embodiments, the lipid feed stock used has an acid number of about 5 (mg KOH/g oil) or greater. In some embodiments, the lipid feed stock used has an acid number of about 10 (mg KOH/g oil) or greater. In some embodiments, the lipid feed stock used has an acid number of about 50 (mg KOH/g oil) or greater.
  • Alcohols used in some embodiments of the invention can include many different types of alcohols.
  • alcohols used in some embodiments of the invention can include alcohols having from one to six carbon atoms.
  • methanol is used.
  • Methanol can be advantageous as the resulting alkyl esters (methyl esters) have a lower viscosity than higher alkyl esters.
  • ethanol is used. Ethanol has low toxicity and is readily produced from plant matter by fermentation processes.
  • a single alcohol is used.
  • a mixture of different alcohols is used.
  • a mixture of methanol and a higher molecular weight alcohol can be used. Such a mixture can offer the advantage of being more miscible with the biological lipid feed stock than methanol alone.
  • both acid-catalyzed and base- catalyzed transesterification is used simultaneously or in series to convert a biological lipid feed stock and an alcohol feed stock into alkyl esters.
  • the reaction mixture of the biological lipid and the alcohol are passed over an acid modified metal oxide catalyst first and then passed over a base modified metal oxide catalyst.
  • the acid modified metal oxide catalyst could be packed into a first column or housing and the base modified metal oxide catalyst could be packed into a second column or housing. Then the reaction mixture can be passed through the first column and then passed through the second column.
  • both an acid modified metal oxide catalyst and a base modified metal oxide catalyst can be packed into one column or housing either in two segments or fully mixed.
  • each segment or column can be separately held at a temperature that optimizes the esterification or transesterification reaction. While not intending to be bound by theory, it is believed that using both an acid modified metal oxide catalyst and a base modified metal oxide catalyst can offer the advantages of fast reaction rates, high yields, and reduced byproducts.
  • embodiments of the invention can include diesel power plant systems including a biodiesel production reactor. Referring now to FIG. 4, a schematic view of a diesel power plant system 200 is shown in accordance with an embodiment of the invention.
  • a continuous-flow biodiesel production reactor 202 is in fluid communication with a diesel engine 204.
  • the continuous-flow biodiesel production reaction 202 includes a biological lipid feed stock reservoir 206 and an alcohol feed stock reservoir 208. Both feed stock reservoirs 206 and 208 are connected to a reactor housing 210.
  • the reactor housing 210 contains a metal oxide catalyst.
  • the biodiesel fuel (including alkyl esters) produced in the reactor housing 210 flow through a conduit 212 into the diesel engine 204.
  • the diesel engine 204 takes in air through an air intake port 214.
  • the incoming air then passes through a valve 216 into a combustion chamber 218.
  • a piston 222 compresses air within the combustion chamber 218 heating it up.
  • the biodiesel fuel is then injected into the combustion chamber 218 through an injection port 220.
  • the heated air within the combustion chamber 218 ignites the fuel and the piston 222 is propelled downward.
  • Exhaust gases from the combustion of the biodiesel fuel pass out of the engine through an exhaust port 224. Heat from the combustion can be used to heat the reactor to a desired optimum temperature.
  • the continuous-flow biodiesel production reactor 202 can produce biodiesel fuel fast enough to supply the diesel engine 204 with fuel without the need for the engine to draw upon stored biodiesel fuel in a separate tank.
  • the biodiesel production reactor 202 can produce biodiesel fuel at a rate exceeding the peak demand rate of the diesel engine 204 to which it is paired.
  • a biodiesel production reactor such as those described herein, along with a diesel engine can be uniquely complementary.
  • the heat of combustion from the engine can be used to heat the reactor 202.
  • heat generated by diesel combustion that needs to be dissipated can be beneficially used as the heat input for the biodiesel production reactor. This is particularly advantageous in the context of methods of producing biodiesel as described herein that include reaction conditions with extremely high temperatures.
  • a cooling system from the engine such as a radiator or other heat exchanger device, may be used to help control the temperature of the reactor 202.
  • the diesel power plant system 200 may also include other components.
  • the diesel power plant system 200 may also include a separation membrane or a centrifugal separation device that can separate glycerol or impurities from the biodiesel fuel.
  • the diesel power plant system 200 can also include a monitoring system that monitors the quality of the biodiesel being produced to ensure that the biodiesel fuel being produced is of a sufficient quality for use in the diesel engine 204.
  • the diesel power plant system 200 is light enough and small enough in size that it can be mounted on or in diesel powered equipment such as vehicles, planes, cars, trucks, ships, construction equipment, earth movers, bulldozers, locomotives, fork lifts, generators, irrigation pumps, tractors, combines, and the like.
  • the invention includes a piece of diesel powered equipment including a housing, a diesel engine disposed within the housing, and a continuous-flow biodiesel production reactor in direct or indirect fluid communication with the diesel engine, the reactor comprising a catalyst housing, and a metal oxide catalyst disposed within the catalyst housing.
  • the relatively small size production reactors that are possible with embodiments of the invention can be disposed on a mobile unit, such as a trailer.
  • Such a mobile unit with a reactor can easily moved to sites that produce feed stock oils, such as farms, and can therefore convert these feed stocks into biodiesel at the farm site where the fuel can be used to satisfy the energy needs of the farm.
  • This approach offers various advantages reducing the need to ship biodiesel fuel thereby reducing another large cost associated with biodiesel fuel production.
  • the invention includes a biodiesel production reactor mounted on a mobile platform such as a trailer or a truck.
  • Example 1 Formation of Zirconia Particles A colloidal dispersion of zirconium oxide (NYACOLTM ZR 100/20) (Nyacol Nano Technologies, Inc., Ashland, MA), containing 20 wt. % Zr ⁇ 2 primarily as about 100 nm particles was spray dried. As the dispersion dried, the particles interacted strongly with one another to provide aggregated Zr ⁇ 2 particles. The dried aggregated particles that were obtained were examined under an optical microscope and observed to consist mostly of spherules from about 0.5 ⁇ m to about 15 ⁇ m in diameter.
  • the dried spherules were then sintered by heating them in a furnace at a temperature of 750° C for 6 hours.
  • the spherules were air classified, and the fraction having a size of approximately 10 ⁇ m was subsequently isolated.
  • the particles were all washed in sodium hydroxide (1.0 Molar), followed by water, nitric acid (1.0 Molar), water and then dried under vacuum at 110° C.
  • BET nitrogen porosimetry was performed in order to further characterize the sintered spherules.
  • the physical characteristics of the spherules were as listed below in Table 2.
  • Example 2 Formation of Sulfuric Acid Modified Zirconia Particles 250 mL of a 1.5M sulfuric acid solution was prepared by adding 36.75 g
  • the heat source was then removed and the flask was allowed to cool down to room temperature.
  • the particle suspension was then filtered on a medium fritted sintered glass funnel.
  • the particles were then rinsed thoroughly with 4 x 200 mL of HPLC grade water and followed by 3x100 mL acetone. Air was then pulled through the particle cake for about 8 hours to dry the particles.
  • Particles as formed in Example 3 were slurried in ethanol (6.5 g zirconia in 24 mL of ethanol) and packed into a 15 cm x 4.6 mm i.d. stainless steel HPLC column at 7,000 PSI using ethanol as a pusher solvent. The column was allowed to pack for 30 minutes under pressure and then the pressure was allowed to slowly bleed off and the end fitting and frit were attached to the inlet of the column.
  • Example 5 Batch Production of Alkyl Esters from Soybean Oil Using Sulfated Zirconia
  • Sulfuric acid modified zirconia (zirconium dioxide) particles as formed in Example 2 were added to a reaction mixture of soybean oil (9 g) and methanol (79 g). A heating device was used to keep the reaction mixture at approximately 100° C. The reaction was allowed to proceed for approximately 27 hours.
  • Sulfuric acid modified zirconia (zirconium dioxide) particles as formed in Example 2 were packed into a stainless steel reactor (column).
  • a heating device Metallox Column Heater, ZirChrom Separations, Inc., Anoka, MN
  • the heating device was set to a temperature of approximately 200° C (though the temperature inside the reactor was less than this).
  • a reaction mixture of hexane (carrier), soybean oil, and methanol were pumped into the column at a flow rate of 1.78 mL/min. Overall pressure of approximately 1000 psi was kept on the column and a back pressure regulator was used.
  • the reaction conditions are summarized in Table 5.
  • Acid modified zirconia (zirconium dioxide) particles as formed in Example 2 were packed into a stainless steel reactor (column).
  • a heating device Metallox Column Heater, ZirChrom Separations, Inc., Anoka, MN
  • the heating device was set to a temperature of approximately 200° C (though the temperature inside the reactor was less than this).
  • a reaction mixture of hexane (carrier), soybean oil, and methanol were pumped into the column at a flow rate of 0.06 mL/min. Overall pressure of approximately 800 psi was kept on the column and a backpressure regulator was used.
  • the reaction conditions are summarized in Table 7.
  • Base modified zirconia (zirconium dioxide) particles as formed in Example 3 were packed into a stainless steel reactor (column).
  • a heating device Metallox Column Heater, ZirChrom Separations, Inc., Anoka, MN
  • the heating device was set to a temperature of approximately 200° C (though the temperature inside the reactor was less than this).
  • a reaction mixture of hexane (carrier), soybean oil, and methanol were pumped into the column at a flow rate of 0.06 mL/min. Overall pressure of approximately 800 psi was kept on the column and a back pressure regulator was used.
  • the reaction conditions are summarized in Table 9. TABLE 9
  • 250 mL of a 6.8% phosphoric acid solution was prepared by adding 20 mL phosphoric acid to 230 mL of HPLC grade water in a 500 mL round bottom flask. 50 g of 5 ⁇ m bare zirconia prepared as described in Example 1 was put into the flask. The particle suspension was then sonicated under vacuum for approximately 10 minutes while swirling to fully suspend the particles. The flask was then attached to a water-cooled condenser and heating mantle. The solution was heated to a slow boil, and then refluxed for approximately 6 hours. The heat source was then removed and the flask was allowed to cool down to room temperature. The particle suspension was then filtered on a medium fritted sintered glass funnel. The particles were then rinsed thoroughly with 3x200 mL of HPLC grade water. Air was then pulled through the particle cake for about 8 hours to dry the particles.
  • Example 10 Formation of a Packed Column of Phosphoric Acid Modified Zirconia Particles
  • Particles as formed in Example 9 were slurried in ethanol (6.4 g zirconia in 24 .5 mL of methanol) and packed into a 15cm x 4.6 mm i.d. stainless steel HPLC column at 7,000 PSI using methanol as a pusher solvent. The column was allowed to pack for 30 minutes under pressure and then the pressure was allowed to slowly bleed off and the end fitting and frit were attached to the inlet of the column.
  • Example 11 Continuous Production of Alkyl Esters from Soybean Oil Using Phosphated Zirconia
  • Phosphoric acid modified zirconia (zirconium dioxide) particles as formed in Example 9 were packed into a stainless steel reactor (column) as described in Example 10.
  • a heating device Metal Organic Heating Device, ZirChrom Separations, Inc., Anoka, MN
  • the heating device was set to a temperature of approximately 200° C (though the temperature inside the reactor was less than this).
  • a reaction mixture of hexane (carrier), w-propanol, soybean oil, and methanol were pumped into the column at a flow rate of 0.06 mL/min. Overall pressure of approximately 1000 psi was kept on the column and a back pressure regulator was used.
  • the reaction conditions are summarized in Table 11.
  • FIG. 5 shows the percent conversion over 51.4 hours of continuous operation. The average percent conversion over this time was 69.1%. The peak conversion was 90.3% and the conversion stabilized around 60% after an initial decrease was observed.
  • Example 12 Continuous Production of Alkyl Esters from Soybean Oil Using Phosphated Zirconia Catalyst
  • a phosphated zirconia column was prepared according to the procedure described in Examples 9 and 10 and was placed in a block heater capable of reaching temperatures as high as 350 0 C.
  • Soybean oil (Sigma-Aldrich) was pumped from a reservoir with an HPLC pump and combined with HPLC-grade methanol that was pumped from a second HPLC pump with a stainless steel "T" that was immersed in silicone oil.
  • the silicone oil was kept at a constant temperature and used to preheat the reactants before they entered the phosphated zirconia column.
  • the phosphated zirconia column was temperature controlled using a fast-response resistive heating block hooked to a dual zone temperature controller.
  • the stainless steel tubing passed through an ice bath to cool the effluent, which then passes through a back pressure regulator, and then to a collection vial. Samples were formed using the reactor at the conditions describe below in Table 12.
  • the fatty acid methyl ester content of each sample was then assessed using GC-FID as described in Example 5. The results of the GC-FID analysis are also shown below in Table 13.
  • the preheater temperature shown in Table 13 reflects the temperature of the silicone oil bath and the reactor temperature shown in Table 13 reflects the temperature of the heating block. Therefore, the actual temperature of the reactants would be somewhat less than these temperatures. It is notable that in this example pure feed stock components (e.g., only soybean oil and methanol) were used with no carrier (such as hexane) to lower the viscosity of the reactant mixture. The highest conversion percentage observed in these experiments was 95.3%. The percent conversion was calculated by assuming that 95% of the soybean oil is triglyceride and that there is a 1 : 1 mass ratio of triglyceride to biodiesel.
  • FIG. 6 shows the percent conversion versus the flow rate, establishing that the flow rate has a direct effect on the conversion efficiency.
  • a byproduct of the transesterification reaction of soybean oil to fatty acid methyl esters includes glycerol.
  • Glycerol is immiscible with the resulting fatty acid methyl esters and can be easily separated using a separatory funnel.
  • Glycerol was separated from a fatty acid methyl ester composition produced with phosphated zirconia as described in Example 12.
  • the glycerol was analyzed using NMR, confirming that glycerol is indeed produced in the reactor as expected. By integration of the NMR peaks, it was estimated that the glycerol produced using phosphated zirconia reactor is roughly 90% pure.
  • Example 14 Comparison of Phosphated Zirconia and Sulfated Zirconia
  • a reactor was then set up similar to as in Example 12.
  • Soybean oil (Sigma- Aldrich) was pumped from a reservoir with an HPLC pump and combined with HPLC-grade methanol that was pumped from a second HPLC pump with a stainless steel "T" that was immersed in silicone oil.
  • the silicone oil was kept at a constant temperature and used to preheat the reactants before they entered either the zirconia column (phosphated or sulfated).
  • the zirconia column was temperature controlled using a fast-response resistive heating block hooked to a dual zone temperature controller. After the zirconia column, the stainless steel tubing passed through an ice bath to cool the effluent, which then passes through a back pressure regulator, and then to a collection vial.
  • the preheater temperature shown in Table 15 reflects the temperature of the silicone oil bath and the column temperature shown in Table 15 reflects the temperature of the heating block. Therefore, the actual temperature of the reactants would be somewhat less than these temperatures.
  • This example shows that phosphated zirconia works substantially better as a catalyst for converting triglycerides and methanol into fatty acid methyl esters (FAMEs) than otherwise similar sulfated zirconia.
  • Example 16 Continuous Production of Alkyl Esters from Soybean Oil Using Acid Modified Carbon Clad Zirconia Catalyst Zirconia particles with an average particle size of 5.03 ⁇ m were prepared as described in accord Example 1. 200 g of the zirconia particles were loaded into a rotating quartz tube reaction chamber and an organic bubbler was filled with HPLC- grade hexane.
  • the entire system was flushed with nitrogen at ambient temperature using the following 5-step method: 1) flow nitrogen through reaction chamber and bubbler at 500 cc/min for 1 min, 2) flip open vent on bubbler to remove trapped air for a few seconds, 3) run nitrogen through bubbler bypass for 3 minutes, 4) shut off flow to auxiliary flow meter and run nitrogen through organic bubbler for 1 min, and 5) shut off flow to organic bubbler and run nitrogen through auxiliary flow meter for 45 min, pass nitrogen through the lines in one direction for 30 minutes and in the reverse direction for 15 min.
  • the temperature of the system was raised to 700° C and nitrogen flow through the system was maintained.
  • the quartz tube was then rotated at 1 revolution per minute.
  • the heated zirconia was then equilibrated with nitrogen gas passing through the system at 500 cc/min.
  • the line to the organic bubbler was then opened so that hexane vapor could pass into the reaction chamber and coating was performed for exactly 30 minutes.
  • the line to the organic bubbler was then closed and the furnace was cooled as quickly as possible by opening the furnace top to a nitrogen flow at 100° C. After the furnace was cooled, the nitrogen flow was shut-off completely and the coated particles were removed and put into an extraction thimble. 100 mL of toluene was added to the thimble and the mixture was stirred with a TEFLON rod to wet particles.
  • Soxhlet extraction was performed with toluene for 12 hours.
  • the particles were then filtered and collected on a sintered glass funnel.
  • the particles were then washed with 200 mL of toluene, 150 mL of 1 : 1 ethanohtoluene, and 250 mL hexane. Finally, air was pulled through the cake until free flowing and then the particles were dried in a vacuum oven at 110° C for roughly 12 hours.
  • the resulting carbon clad zirconia had 1% carbon content by elemental analysis.
  • the carbon clad zirconia was then treated with phosphoric acid according the following procedure.
  • 250 mL of a 6.8% phosphoric acid solution was prepared by adding 10 mL phosphoric acid to 115 mL of HPLC grade water in a 500 mL round bottom flask.
  • 25 g of the 5.03 ⁇ m carbon clad zirconia described above was put into the flask.
  • the particle suspension was then sonicated under vacuum for approximately 10 minutes while swirling to fully suspend the particles.
  • the flask was then attached to a water-cooled condenser and heating mantle. The solution was heated to a slow boil, and then refluxed for approximately 6 hours. The heat source was then removed and the flask was allowed to cool down to room temperature.
  • the particle suspension was then filtered on a medium fritted sintered glass funnel.
  • the particles were then rinsed thoroughly with 3x100 mL of HPLC grade water and 3 x 100 mL of HPLC grade ethanol. Air was then pulled through the particle cake for about 8 hours to dry the carbon clad zirconia particles.
  • the carbon clad zirconia particles were slurried in ethanol (6.0 g zirconia in 24.5 mL of chloroform) and packed into a 15 cm x 4.6 mm i.d. stainless steel HPLC column at 11,000 PSI using pentane as a pusher solvent. The column was allowed to pack for 30 minutes under pressure and then the pressure was allowed to slowly bleed off and the end fitting and frit were attached to the inlet of the column.
  • a heating device Metal Organic Heater, ZirChrom Separations, Inc., Anoka, MN set at 200° C was used to heat the packed column (the actual temperature of the reactants inside the column would be somewhat less than 200° C).
  • a reaction mixture of hexane, soybean oil, and methanol were pumped into the column at a flow rate of 0.06 mL/min. Overall pressure of approximately 800 psi was kept on the column and a back pressure regulator was used. The reaction products were then analyzed using gas chromatography as described in Example 5 above. The results are shown in FIG. 8. Under these conditions there was a slight drop in conversion rate and then it leveled off.
  • Example 17 Conversion of a Free Fatty Acid (Stearic Acid) to Alkyl Esters
  • a sample of phosphated zirconia (average size of 5 microns) was prepared in accordance with the procedures described above in Example 9 and then packed into a column.
  • Stearic acid (Sigma-Aldrich) was pumped from a reservoir with an HPLC pump and combined with HPLC-grade methanol that was pumped from a second HPLC pump with a stainless steel "T".
  • the zirconia column was heated using a fast-response resistive heating block (set at 200 degrees Celsius) hooked to a dual zone temperature controller (the actual temperature of reactants inside the column was less than 200 degrees).
  • the stainless steel tubing passed through an ice bath to cool the effluent, through a back pressure regulator, and then to a collection vial.
  • Example 18 Conversion of Yellow Grease to Alkyl Esters A sample of phosphated zirconia (average size of 5 microns) was prepared in accordance with the procedures described above in Example 9 and then packed into a column.
  • a sample of yellow grease was obtained from Restaurant Technologies, Inc. (Eagan, MN) and observed to contain a substantial amount of particulate material.
  • the yellow grease was prepared by first filtering it through a 10 micron "sock” filter, then filtering through a course paper filter (Whatman #1) and then finally through a 0.45 micron nylon filter.
  • a reactor was then set up similar to as in Example 12.
  • the prepared yellow grease (Sigma-Aldrich) was pumped from a reservoir with an HPLC pump and combined with HPLC-grade methanol that was pumped from a second HPLC pump with a stainless steel "T" that was immersed in silicone oil.
  • the silicone oil was kept at a constant temperature and used to preheat the reactants before they entered either the sulfated zirconia column.
  • the zirconia column was temperature controlled using a fast-response resistive heating block hooked to a dual zone temperature controller. Various temperatures for the zirconia column were used as shown below in Table 18.
  • the stainless steel tubing passed through an ice bath to cool the effluent, which then passes through a back pressure regulator (back pressure kept at 1600 psi), and then to a collection vial.
  • the reaction was then run at the conditions described below in Table 18. It should be noted that the preheater temperature shown in Table 18 reflects the temperature of the silicone oil bath and the reactor temperature shown in Table 18 reflects the temperature of the heating block. Therefore, the actual temperature of the reactants would be somewhat less than these temperatures.
  • the effluent from the columns was then collected and analyzed by GC-FID as described in Example 5. The results of the GC-FID analysis are shown below in Table 18 wherein FAME refers to fatty acid methyl esters.
  • Example 19 Formation of Phosphoric Acid Modified Titania Particles 125 mL of a 6.8% phosphoric Acid solution was prepared by adding 10 mL phosphoric acid to 115 mL of HPLC grade water in a 250 mL round bottom flask. 25 g of 5 ⁇ m bare titania (Sachtleben, Germany) was added to the flask. Table 19 shows the physical characteristics of the porous titania particles.
  • the particle suspension was then shaken by hand under vacuum for approximately 20 minutes while swirling to fully suspend the particles.
  • the flask was then attached to a water-cooled condenser and heating mantle. The solution was heated to a slow boil, and then refluxed for approximately 6 hours.
  • the heat source was then removed and the flask was allowed to cool down to room temperature.
  • the particle suspension was then filtered on a medium fritted sintered glass funnel.
  • the particles were then rinsed thoroughly with 3x100 mL of HPLC grade water. Air was then pulled through the particle cake for about 8 hours to dry the particles.
  • Acid modified titania (titanium dioxide) particles as formed in Example 20 were packed into a stainless steel reactor (column).
  • a heating device Metallox Column Heater, ZirChrom Separations, Inc., Anoka, MN
  • a reaction mixture of hexane, soybean oil, and methanol were pumped into the column at a flow rate of 0.06 mL/min.
  • Overall pressure of approximately 1,000 psi was kept on the column and a back pressure regulator was used.
  • the reaction conditions are summarized in Table 20.
  • Example 21 Conversion of Soybean Oil to Alkyl Esters Using Hydroxide Modified Titania Catalyst
  • Titania particles were obtained (20 ⁇ m average diameter and 300 Angstrom average pore size) and then modified with sodium hydroxide according to the procedure described in Example 3 above.
  • the resulting hydroxide modified titania particles were then packed into a stainless steel reactor (column) with dimensions of 150 mm in length and 4.6 mm in width.
  • a heat exchange system was used to both heat the reactants and cool the reaction products.
  • a coil preheater was used to raise the temperature of reactants before entering the stainless steel reactor.
  • the coil preheater included tubing wound around a grooved heater core with a resistive heater disposed in the middle of the core.
  • a thermocouple was used to monitor the preheater core temperature.
  • a column heater was used to regulate the temperature of the reactor. The column heater was a tube furnace heater. Both the soybean oil and the methanol were sparged with nitrogen gas.
  • a degasser was used on the methanol inlet. Soybean oil and methanol were separately pumped, at the flow rates indicated below, the flow streams were then joined and then passed into the stainless steel reactor. Pressure regulators were used to maintain pressure within the reactor as indicated below. The reaction conditions are summarized in Table 22.
  • This example shows that base modified titania particles can be used in a continuous process for producing alkyl esters. This example also shows that exceeding a desirable reaction temperature while using a titania catalyst can result in a reduction in the conversion of the feed stock into fatty acid methyl esters.
  • the use of titania can be advantageous because it is generally less expensive than some other metal oxides, such as zirconia.
  • the zirconia particles formed as described in Example 1 were coated with polybutadiene (PBD) by the following method.
  • PBD polybutadiene
  • 2.5 g PBD was added to a 500 mL round bottom flask. The volume was brought up to 75 ml w/ HPLC grade hexane and the flask was swirled until PBD is fully dissolved.
  • 45g of bare zirconia was added to the 500 mL round bottom flask (A/B washed) and resulting slurry was sonicated for a few minutes under vacuum, breaking the vacuum periodically (about 5 min).
  • 2.03 grams of a stock solution of dicumyl peroxide (DCP) was added (stock solution made by adding 0.25g DCP into 8.25 g hexane).
  • DCP dicumyl peroxide
  • the slurry was sonicated under vacuum for 5 minutes, breaking vacuum every minute to allow infiltration of particle pores.
  • the flask was rotated on a rotary station for 2 hours.
  • a rotary evaporator was used to evaporate solvent at 55° C with a vacuum of 14 in Hg over a period of 15 minutes.
  • the material was allowed to continue to dry for 15 minutes at 55° C under a vacuum of 14 in Hg.
  • Particles were transferred to a clean quartz tube and washed repeatedly with hexane.
  • the quartz tube was placed in a rotating furnace and then connected a supply of ultra pure nitrogen and flushed for 30 min.
  • the particles were dried at 110° C for 1 hour, then the temperature was raised to 160° C and the material cross- linked at 160° C for 5 hrs, all while running ultra pure nitrogen through the tube.
  • Particles were transferred from the tube to a soxhlet extractor. 500 mL of toluene was used with the extractor for 8 hours.
  • the particles were collected on a membrane filter and rinsed with 2 x 100 mL of ethanol. Air was pulled through the cake for three hours until the particles were dry.
  • the particles were resuspended in 200 mL 50/50 0.2M NaOH/THF in a 1 liter Erlenmeyer flask. The material was then sonicated under vacuum for 5 minutes, breaking vacuum once every minute. The particles were filtered and then dried by pulling air through the cake for 1 hour. The washing step was repeated two more times. The particles were rinsed while on a filter with 2 x 100 mL HPLC ethanol, and then dried by pulling air through the cake for 3 hours.
  • the heat source was then removed and the flask was allowed to cool down to room temperature.
  • the particle suspension was then filtered on a medium fritted sintered glass funnel.
  • the particles were then rinsed thoroughly with 3 x 100 mL of HPLC grade water and then washed with 3 x 100 mL of ethanol. The particles were then dried under vacuum for 2 hours.
  • Example 23 Production of Fatty Acid Methyl Esters Using Acid Modified Polybutadiene Coated Zirconia Particles
  • Acid modified PBD coated zirconia (zirconium dioxide) particles as formed in Example 23 were packed into a stainless steel reactor (column).
  • a heating device Metallox Column Heater, ZirChrom Separations, Inc., Anoka, MN
  • a reaction mixture of hexane, soybean oil, and methanol were pumped into the column at a flow rate of 0.06 mL/min.
  • Overall pressure of approximately 1,000 psi was kept on the column and a back pressure regulator was used.
  • the reaction conditions are summarized in Table 24.
  • Example 24 Conversion of Soybean Oil to Alkyl Esters Using Hydroxide Modified Zirconia Catalyst, Phosphoric Acid Modified Zirconia Catalyst, and Control
  • Zirconia particles were obtained (25 ⁇ m average diameter and 300 Angstrom average pore size) and then modified with sodium hydroxide according to the procedure described in Example 3 above to form a first catalyst ("BMZ").
  • Zirconia particles were obtained (25 ⁇ m average diameter and 300 Angstrom average pore size) and then modified with phosphoric acid according to the procedure described in Example 9 above to form a second catalyst ("PMZ").
  • Titania particles were obtained (20 ⁇ m average diameter and 300 Angstrom average pore size) and then modified with sodium hydroxide according to the procedure described in Example 3 above to form a third catalyst ("PMT").
  • a fourth catalyst consisted of unmodified zirconia (25 ⁇ m average diameter and 300 Angstrom average pore size).
  • a fifth catalyst consisted of unmodified alumina particles. The catalyst particles were then packed into a stainless steel reactor (columns) with dimensions of 150 mm in length and 4.6 mm in width.
  • a heat exchange system was used to both heat the reactants and cool the reaction products.
  • a coil preheater was used to raise the temperature of reactants before entering the stainless steel reactor.
  • the coil preheater included tubing wound around a grooved heater core with a resistive heater disposed in the middle of the core.
  • a thermocouple was used to monitor the preheater core temperature.
  • a column heater was used to regulate the temperature of the reactor. The column heater was a tube furnace heater.
  • a degasser was used on the methanol inlet.
  • a feed stock oil (as shown in Table 27) and methanol were separately pumped, at the flow rates indicated below, the flow streams were then joined and then passed into the stainless steel reactor.
  • Pressure regulators were used to maintain pressure within the reactor as indicated below. The reaction conditions are summarized in Table 26.
  • the effluent was then analyzed by using 300 MHz 1 H NMR. Further aspects of the reaction conditions, and the percent conversion as calculated using 300 MHz 1 H NMR, are shown below in Table 27. A significant amount of gas was evolved during some of the reactions. A sample of this gas was evaluated using near infrared spectroscopy (NIR) and found to include dimethyl ether, methane, carbon monoxide, and carbon dioxide.
  • NIR near infrared spectroscopy
  • FIG. 9 shows the effect of average reactor temperature ((inlet temperature + outlet temperature)/2) on conversion percentage. Specifically, FIG. 9 shows the conversion percentages for sample 4 (354.5° C), sample 5 (309° C), and sample 7 (405° C).
  • This example shows that very low residence times (5.9 seconds) can be achieved using supercritical conditions and metal oxide catalysts as described herein.
  • This example further shows that unmodified metal oxides catalysts can be used to achieve high conversion rates when using supercritical conditions.
  • the swine tallow used in sample 11 was determined to have an acid number of 5.11.
  • this example further shows that methods and catalysts of the invention can be used to convert low value feed stocks having relatively high free fatty acid content (high acid number) into biodiesel fuel at a high percent conversion.
  • Zirconia particles were obtained (25 ⁇ m average diameter and 300 Angstrom average pore size) and then modified with sodium hydroxide according to the procedure described in Example 3 above.
  • the resulting hydroxide modified zirconia particles were then packed into a stainless steel reactor (column) with dimensions of 150 mm in length and 4.6 mm in width.
  • a heat exchange system was used to both heat the reactants and cool the reaction products.
  • a coil preheater was used to raise the temperature of reactants before entering the stainless steel reactor.
  • the coil preheater included tubing wound around a grooved heater core with a resistive heater disposed in the middle of the core.
  • a thermocouple was used to monitor the preheater core temperature.
  • a column heater was used to regulate the temperature of the reactor. The column heater was a tube furnace heater.
  • SA Stearic acid
  • butanol Stearic acid
  • a degasser was used on the methanol inlet.
  • the 10% SA solution and the methanol were separately pumped, at the flow rates indicated below, the flow streams were then joined and then passed into the stainless steel reactor. Pressure regulators were used to maintain pressure within the reactor as indicated below.
  • the reaction conditions are summarized in Table 28. TABLE 28
  • This example shows that base modified zirconia particles can be used in a continuous process for producing esters from free fatty acids.
  • Titania particles were obtained (80 ⁇ m average diameter and 60 Angstrom average pore size) and then modified with sodium hydroxide according to the procedure described in Example 3 above.
  • the resulting hydroxide modified titania particles were then packed into a first and second stainless steel reactor (column) with dimensions of 150 mm in length and 4.6 mm in width each.
  • a heat exchange system was used to both heat the reactants and cool the reaction products.
  • a coil preheater was used to raise the temperature of reactants before entering the first stainless steel reactor.
  • the coil preheater included tubing wound around a grooved heater core with a resistive heater disposed in the middle of the core.
  • a thermocouple was used to monitor the preheater core temperature.
  • Column heaters were used to regulate the temperature of the reactors.
  • FIG. 1OA shows the preheater core temperature and the temperature of the reaction mixture as measured between the two reactors.
  • FIG. 1OB shows the percent conversion over time as measured using NMR.
  • This example shows that catalysts of the invention can be used to convert feed stocks into fatty acid alkyl esters at a high percentage yield over an extended period of time. As such, this example shows that catalysts of the invention are resistant to catalyst poisoning.

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Abstract

La présente invention concerne des procédés et un appareil permettant de produire des esters d'alkyles à partir de matériaux de départ lipidiques, par exemple des essences de plante et/ou des graisses animales, et des systèmes les utilisant. Un mode de réalisation de l'invention concerne un procédé de production d'esters d'alkyles impliquant les étapes consistant à mélanger un matériau de départ lipidique avec un alcool afin de former un mélange réactionnel, et à mettre en contact ledit mélange réactionnel avec un catalyseur dans des conditions supercritiques pour l'alcool, le catalyseur comprenant un oxyde métallique non modifié choisi dans le groupe comprenant l'alumine, le dioxyde de titane, la zircone et le dioxyde d'hafnium, puis enfin à éliminer les acides gras libres résiduels du mélange réactionnel. D'autres modes de réalisation sont décrits dans l'invention.
EP07840692A 2006-08-04 2007-08-03 Procédés et appareil permettant de produire des esters d'alkyles à partir de matériaux de départ lipidiques et systèmes les utilisant Withdrawn EP2069465A2 (fr)

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US8445709B2 (en) * 2006-08-04 2013-05-21 Mcneff Research Consultants, Inc. Systems and methods for refining alkyl ester compositions
US9102877B2 (en) 2008-11-12 2015-08-11 Sartec Corporation Systems and methods for producing fuels from biomass
WO2010144597A1 (fr) * 2009-06-09 2010-12-16 Mcneff Research Consultants, Inc. Systèmes et procédés pour raffiner des compositions d'ester alkylique
US8557001B2 (en) 2009-11-24 2013-10-15 Shell Oil Company Fuel formulations
US8663346B2 (en) 2009-11-24 2014-03-04 Shell Oil Company Fuel formulations
US10239812B2 (en) 2017-04-27 2019-03-26 Sartec Corporation Systems and methods for synthesis of phenolics and ketones
US10544381B2 (en) 2018-02-07 2020-01-28 Sartec Corporation Methods and apparatus for producing alkyl esters from a reaction mixture containing acidified soap stock, alcohol feedstock, and acid
US10696923B2 (en) 2018-02-07 2020-06-30 Sartec Corporation Methods and apparatus for producing alkyl esters from lipid feed stocks, alcohol feedstocks, and acids

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