Esterification of free fatty acids using water-tolerable Amberlyst as a of heterogeneous acid catalysts, Amberlyst 15 and Amberlyst BD The grant supports Rohm and Haas’s development of a newly commercial polymeric catalyst technology, AMBERLYST™ BD20 specialty. When the FFA contents of oils were and wt%, the activity of Amberlyst 15 gradually decreased with recycling, whereas the activity of Amberlyst BD
This application is based upon U. The present invention generally relates to converting carboxylic acids into esters by esterification with alcohols in the presence of dual catalysts. Vegetable oils and animal fats and their by-products can contain considerable amounts of free fatty acids. When these materials are used for fatty acid alkyl ester FAAE production by base-catalyzed transesterification of mono- di- and tri-acylglycerides i.
A pretreatment process may be used to reduce the FFA content in the raw materials i. One method to reduce the FFA level in fats and oils is to remove them by distillation. This process reduces the overall yield of feedstock to FAAE though and generates a stream of concentrated FFA that requires finding a new end-use, further processing or disposal.
Another common method to remove small amounts of FFA is by adding a base reactant such as sodium hydroxide in order to saponify the FFA to soap which allows removal by water washing and filtration. Another pretreatment process used to convert FFA into esters is acid catalyzed esterification. The FFA esterification reaction is affected by temperature, molar ratio of alcohol to FFA, mass transfer limitations, catalyst concentration, reaction time, and reaction stoichiometry. Since esterification reactions are reversible, the reaction does not go to completion.
However, these equilibrium-limited reactions can be propelled further by increasing the concentration of the reactants or decreasing the concentration of the products.
The reaction can be summarized as follows:. Further FFA conversion can be accomplished by removing water from the reaction products either continuously amberlsyt between reaction stages by distillation, flash evaporation, decanting or other such means. However, additional reaction stages require capital investment for additional unit operations as well as additional operating expenses. Esterification reactions can also be aided with excess alcohol and catalyst addition, although economic factors, small incremental improvements, and additional amberlyzt complexity usually limit their effectiveness.
Esterification reactions can be performed in ambelyst batch or continuous process applications. One such esterification process converts free fatty acids anberlyst FAAEs with alcohols using homogenous catalysis catalyst and reactants have the same phase. Homogenous catalysis provides excellent selectivity and activity. Sulfuric acid, p-toluene sulfonic acid, and other strong acid bx20 have been used for esterification, but process equipment corrosion, product contamination, and catalyst recovery, neutralization, disposal, health and safety concerns and continuous cost issues remain—especially for conversion of renewable feedstocks with high FFA content into biofuels.
Free fatty acids in raw materials can also be esterified with alcohols using heterogeneous catalysis i.
Heterogeneous catalysis often provides good selectivity and, unlike most homogeneous catalysts, are designed to be used for extended periods of time, which avoids the continuous operating expense of unrecoverable homogeneous catalysts. However, heterogeneous esterification activity is generally less than with amberlust catalysts, and multiple stages or extreme operating conditions are typically required to achieve acceptable conversions.
Heterogeneous catalysis is employed on a global commercial scale in the petroleum chemicals and fuels industries, for example, in which extreme operating conditions are used. However, there are unresolved concerns about catalyst fouling, durability, stability, activity, and replacement schedule with continuous use of commercial-grade higher FFA feedstocks.
Potential causes of this steady deactivation include catalyst fouling and deactivation amberlywt proteins, phospholipids, metal ions, neutralization, chemical compounds i. Since such deactivation is not acceptable for commercial operation, new strategies must amberlyat developed to continuously maintain heterogeneous catalyst activity while simultaneously promoting the acid esterification reaction.
It is technically feasible to regenerate deactivated ion exchange catalyst with strong acids hydrochloric, sulfuric, and possibly methane sulfonic. However, catalyst regeneration requires capital and operating expenditures for additional process units and typically cannot recover the initial level of activity.
Furthermore, regeneration or catalyst replacement is a time-consuming and waste-generating activity which puts normal plant production on hold and adds costs for waste disposal. What is needed in the art are methods that improve upon the amberlystt challenges and disadvantages posed by homogenous and heterogeneous catalyst use for esterification of carboxylic acids.
One method of esterification using a dual catalyst process produces a sufficiently low FFA product stream from a reactor with predictable and stable activity over time. A dual catalyst process can also reduce the continuous operating expense of using unrecoverable homogeneous catalysts by reducing the amount of homogeneous catalyst required to obtain the advantages of homogeneous catalyst use.
Esterification of free fatty acids using water-tolerable Amberlyst as a heterogeneous catalyst.
The advantages of the technology described may be better understood by referring to the descriptions below with the accompanying drawings. The drawings are not to scale and represent exemplary configurations that depict general principles of the technology which are not meant to limit the scope of the invention.
Dotted lines within amberlyet figures are representative of optional process streams which may be included as part of the process. After a prescribed residence time the reaction mixture exits the reactor having reduced free fatty acids compared to the feedstock entering the reactor. After a bbd20 residence time and set of operating conditions the second reaction mixture exits the reactor with reduced free fatty acids and enters a separation stage.
The final reaction mixture has ajberlyst free fatty acids compared to the feedstock entering and to the aamberlyst mixture leaving the first reactor. The apparatus, devices, systems, and methods of the present invention will now be described in detail by reference to various non-limiting embodiments, including the figures which are exemplary only. The present invention may be practiced by implementing process steps ambeglyst different orders than as specifically set forth herein.
The present invention may be practiced by implementing process units in different orders than as specifically set forth herein. These feedstocks may or may not have been pretreated using means understood by one skilled in the art to remove impurities.
Biodiesel Magazine – The Latest News and Data About Biodiesel Production
Some variations of the present invention consist of a method of esterification using a dual catalyst process amberltst produces a product stream with sufficiently bd2 FFA in which the amount of FFA in the product stream leaving the process remains stable over time.
The methods of the invention can accommodate a wide range of feedstocks. In some embodiments of the invention, nonexclusive examples of feedstock are fats and oils including coconut oil, palm oils, palm kernel oil, cottonseed oil, rapeseed oil, peanut oil, olive oil, linseed oil, babassu oil, tea oil, Chinese tallow oil, olive kernel oil, meadowfoam be20, chaulmoorgra amberlyat, coriander oil, canola oil, soybean oil, camelina oil, castor oil, pennycress oil, lard oil, jatropha oil, sunflower oil, algae oils, corn oil, used cooking oils, bacon grease, choice white grease, yellow grease, brown grease, poultry fat, beef tallow, lard, and fish oils.
Additionally, feedstocks may include purified or distilled fats and oils including fatty acid distillates, palm fatty acid distillate, and others. According to the invention in its most basic form, carboxylic acids are converted into esters by esterification with alcohol and a dual catalyst.
Bayer and Dow sign worldwide biodiesel technology licensing agreement
One method of the invention, with reference to FIG. After a prescribed residence time and set of operating conditions the reaction mixture 3 exits the reactor containing less carboxylic acid than the feedstock 1.
In one embodiment, the feedstock containing carboxylic acid 1 is pretreated to remove impurities and dried to remove moisture before entering the reactor In one embodiment, alcohol 2 is introduced to a feedstock containing carboxylic acid 1 and homogenous catalyst. In another embodiment the homogenous catalyst is introduced to the reactor separately from the alcohol 2 and the feedstock containing carboxylic acid amber,yst. In another embodiment, the amount of homogenous catalyst introduced to a reactor is between 0.
In yet another embodiment, the amount of homogenous catalyst introduced to a reactor is between 0. The reaction is conducted ambedlyst at least a stoichiometric amount of alcohol as determined on an FFA basis according to Equation 1. In one embodiment the reaction is conducted using a 0.
Alcohol levels greater than 30 molar excess typically provide minimal benefit for first stage reactions, although in some embodiments greater than 30 molar excess may be desirable.
The reaction should take place under sufficient pressure to maintain the alcohol in a liquid state at the desired reaction temperature.
In some situations the pressure may be below the vapor pressure of the alcohol although the alcohol may reflux back into the reaction mixture. Pressure is generally maintained at a constant level throughout the reaction. In one embodiment the pressure is maintained between 0 and psig. In another embodiment, the reaction pressure is maintained between 1 and psig.
The reaction should take place at an elevated temperature to improve reaction kinetics. The reaction temperature may be maintained by electric heat, steam, thermal fluid or other such industrial means practiced by one skilled in the art.
The reactor should be sized to provide sufficient residence time for the carboxylic acid contained in the feedstock 1 to be converted sufficiently to esters. In one embodiment the apparent residence time of reactants in the heterogeneous catalyst bed is between 2 and minutes. In another embodiment, the residence time is between 5 and minutes. In yet another embodiment, the residence time is between 10 and 60 minutes.
The reactor contains a predetermined amount of heterogeneous catalyst. In one embodiment, the WHSV is selected between 0. In another embodiment, the WHSV is selected between 0. The reactor may be configured and oriented in a number of ways. It may be a continuously-stirred tank, plug-flow, tubular-flow, mixed-flow, fixed bed, fluidized bed, batch, semi-batch, recirculating, or other reactor type.
The reactor may be oriented either horizontally or vertically. In a vertical configuration, the reactants may flow upwards or downwards through the reactor The reactor may have freeboard space above the catalyst bed to allow for catalyst movement and expansion as known to those skilled in the art.
The reactor may be fitted with provisions to add and remove heterogeneous catalyst, including by means of motive fluid flow. In one embodiment, method in FIG.
In another embodiment method is repeated in series with method In another embodiment method is conducted in parallel with method In another embodiment method is repeated one or more times in series or parallel with method Another method of the invention, with reference to FIG.
Unit may be an inline mixer, stirred tank, continuously stirred-tank reactor or other such unit operation depending on the desired operating conditions as determined by someone skilled in the art. A first reaction mixture 3 containing lower quantities of carboxylic acid than the feedstock 1 exits unit and enters a reactor containing heterogeneous catalyst. After a prescribed residence time a second reaction mixture 5 exits the reactor containing lower quantities of carboxylic acid than both the feedstock 1 and the first reaction mixture 3.
The second reaction mixture 5 enters unit which may be a decanter, centrifuge, flash evaporator, flash drum, vacuum distillation column, or other similar separation unit. Depending on the unit operation desired, unit may operate at temperatures and pressures above or below atmospheric conditions.
In one embodiment, alcohol, water, and other volatiles 6 are removed from the second reaction mixture 5 contained in unit by distillation leaving a dry reaction mixture 7 also referred to herein as the oil phase that may contain a portion of homogenous catalyst. In another embodiment, a portion of alcohol, water, and homogenous catalyst 6 are removed from the second reaction mixture 5 contained in unit by decantation or centrifugation, leaving a principally dry reaction mixture 7.
In one embodiment, operating conditions of unit are selected to minimize the amount of homogenous catalyst in stream 6 thereby maximizing the amount of the homogenous catalyst in stream 7. In one embodiment the second reaction mixture 5 is washed with water before entering a decanter In any embodiment, dry reaction mixture 7 may continue to a transesterification process, alcohol may be recovered from stream 6 and a portion of homogenous catalyst may be recovered from either stream 6 or 7.
In any embodiment it may be preferable to minimize the amount of moisture in stream 7. In one embodiment, feedstock containing carboxylic acid 1 and also containing homogenous catalyst and alcohol 2 is introduced to the reactor In one embodiment the homogenous catalyst is introduced to the reactor separately from the alcohol 2 and the feedstock containing carboxylic acid 1.
In one embodiment, the operating conditions in units and are substantially similar to those described previously for unit In one embodiment, the reaction time in unit is around minutes, and in another embodiment the reaction time is around minutes. In a different embodiment, the temperature, residence time, alcohol to FFA molar ratio, and other operating conditions are different for unit and unit
Privacy & Cookies Policy
Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.