HK1218556B - Pyrolysis reactions in the presence of an alkene - Google Patents

Abstract

Described herein are methods for producing branched alkanes and branched alkenes from the pyrolysis of radical precursors in the presence of one or more alkenes. The branched alkanes and branched alkene have numerous applications as fuels, platform chemicals, and solvents.

Description

Pyrolysis reaction in the presence of olefins

Technical Field

This application claims priority to U.S. provisional application serial No. 61/792,544, filed on 3, 15, 2013. All teachings of this application are incorporated herein by reference in their entirety.

Background

There is an increasing social and economic pressure to develop renewable energy sources and renewable and biodegradable industrial and consumer products and materials. The catalytic conversion of natural feedstocks into value-added products has resulted in new methods and techniques for their application across the traditional economic field. There is new interest in biorefineries that can be described as processing agricultural and forestry feedstocks to capture the added value by processing them into a variety of products including platform chemicals, fuels, and consumer products. The conversion of tallow and other organic oils to biodiesel has been extensively studied previously. Traditionally, this conversion involves transesterification of triglycerides to produce three methyl esterified fatty acids and one free glycerol molecule. The chemical, rheological, and combustion properties of the resulting "biodiesel" have also been extensively studied. Unfortunately, these methyl ester-based fuels have been shown to be much more susceptible to oxidation and have lower heating values than traditional petroleum-based diesel fuels. Thus, traditional biodiesel must be blended with existing diesel stock and may also have to be supplemented with antioxidants in order to extend shelf life and avoid deposit formation in tanks, fuel systems, and filters.

A relatively immature alternative that has been used in the industry before is pyrolysis if methyl esterification can be considered a clean, controlled reaction. Pyrolysis involves the thermal treatment of agricultural substrates to produce liquid fuel products. Most of the literature reports the use of raw, untreated agricultural products to produce value-added fuels. Many different methods of pyrolysis have been reported in the literature as a mechanism for producing liquid fuels and fall under different protocols including rapid, fast and slow pyrolysis. Pyrolysis of various agricultural products including castor oil, pine, sweet sorghum, and canola under these different protocols has been previously investigated. Depending on the conditions used, including the temperature used, residence time, and purity of the substrate, the equilibrium of the product produced varies between vapor, liquid, and residual solid (char).

One of the few studies focused on the pyrolysis of fatty acids rather than triglycerides or more complex substrates focused on the pyrolysis of salts of the fatty acids. The conditions used in this study were such that no homogeneous decarboxylated product was produced. But rather a mixture of hydrocarbon decomposition products is produced and such a mixture has not been identified by the authors. In general, decarboxylation of carboxylic acids without other interacting functional groups at high temperatures and pressures is poorly understood from the literature. Obtaining a better basic understanding of the chemistry and processes necessary to promote the decarboxylation of fatty acids or the cracking reactions of larger and smaller alkanes and alkenes may allow the development of new fuels and solvent technologies in the future. In one aspect, described herein is the heat treatment of fatty acids under anoxic conditions. Processes of this nature are likely to produce higher grade fuels than traditional biodiesel, and will also likely produce higher yields of the desired product than pyrolysis.

Disclosure of Invention

Described herein are methods for producing branched alkanes and branched alkenes from the pyrolysis of free radical precursors. These branched alkanes and branched alkenes have a variety of applications as fuels, platform chemicals and solvents. The advantages of the materials, methods, and articles described herein will be set forth in part in the description which follows or may be learned by practice of the aspects described below. The advantages described below will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive.

Drawings

The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects described below.

Figure 1 illustrates the proposed mechanism for forming branched olefin compounds from the reaction of alkyl radical species with ethylene and propylene.

Figure 2 illustrates the proposed mechanism for forming alkane branching compounds from the reaction of alkyl radical species with ethylene and propylene.

Figure 3 shows alkane (linear, branched and cyclic) compositions of liquid oleic acid pyrolysis products from a pyrolysis reaction using nitrogen, ethylene, and propylene at 410 ℃ for 2 h.

Figure 4 shows the olefin (linear, branched and cyclic) composition of the liquid oleic acid pyrolysis product from a pyrolysis reaction at 410 ℃ for 2h using nitrogen, ethylene, and propylene.

Figure 5 shows the liquid product yields under nitrogen and ethylene atmospheres at different initial headspace pressures.

Fig. 6 shows a GC-FID chromatogram of a liquid oleic acid pyrolysis product resulting from a reaction under nitrogen (a) and ethylene (B) headspace. The reaction was carried out at 410 ℃ for 2 hours.

Figure 7 shows the total branched alkanes and alkenes in the liquid product at different initial headspace pressures under nitrogen and ethylene atmospheres.

Figure 8 shows a GC-FID chromatogram of oleic acid pyrolysis product from a reaction at 430 ℃ at an initial pressure of 500psi for 2 hours using nitrogen and ethylene.

Figure 9 shows the carbon monoxide content in the gaseous product of nitrogen and ethylene headspace at different initial pressures. At a 95% confidence level, there was no significant difference between headspace gases at the same pressure with the same number above the rod. For the same headspace gas at different initial headspace pressures, bars with the same letter do not have a significant difference at a% confidence level of 95.

Figure 10 shows the carbon dioxide content in the gaseous product of nitrogen and ethylene headspace at different initial pressures. At a 95% confidence level, there was no significant difference between headspace gases at the same pressure with the same number above the rod. For the same headspace gas at different initial headspace pressures, bars with the same letter do not have a significant difference at a% confidence level of 95.

Detailed Description

Before the present materials, articles, and/or methods are disclosed and described, it is to be understood that the aspects described below are not limited to specific compounds, synthetic methods, or uses, as such aspects may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.

In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined to have the following meanings:

throughout this specification, unless the context requires otherwise, the word "comprise", "comprises", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

It must be noted that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "an oil" includes a single oil or a mixture of two or more oils.

"optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

Described herein are methods for producing branched alkanes and branched alkenes from a free radical precursor. In one aspect, the method involves heating a source having one or more free radical precursors in the presence of one or more olefins. The phrase "source of free radical precursors" is defined herein as any material containing carbon-based molecules that can be converted to free radicals when pyrolyzed in the presence of an olefin. In one aspect, the source of the free radical precursor can be a heavy oil, a biomass feedstock, or a fatty acid resource.

The term "heavy oil" as defined herein is any source or form of viscous oil. For example, one heavy oil source includes tar sands. Tar sands, also known as oil sands or tar sands, are a combination of clay, sand, water, and bitumen.

The term "biomass feedstock" as defined herein refers to material from a biological source (such as, for example, plants) that can be converted into an energy source. In some aspects, the energy source is renewable. In one aspect, the biomass feedstock is a lignocellulosic material. "lignocellulosic material" is any dry material from a plant and includes a minimal amount of carbohydrates (such as cellulose and hemicellulose) and/or polyphenolic compounds (such as lignin). Lignocellulosic material may be obtained from agricultural residues (such as, for example, corn stover or wheat straw), from byproducts of wood or paper processing (such as, for example, sawdust or paper mill waste), from crops used for biomass production, from municipal waste (such as, for example, paper), or combinations thereof.

The term "fatty acid resource" as defined herein is any source of fatty acids. The fatty acid may comprise a free fatty acid or a corresponding salt thereof. The term "free fatty acid" is referred to herein as the acid form of the fatty acid (i.e., the terminal-COOH group) and is not a corresponding salt. Alternatively, the fatty acid resource may comprise a fatty acid precursor. For example, the fatty acid precursor may be a lipid, a triglyceride, a diglyceride, or a monoglyceride.

Examples of fatty acid resources include, but are not limited to, vegetable oils, animal fats, lipids derived from biosolids, waste cooking oils, lipids, phospholipids, soapstocks, or other sources of triglycerides, diglycerides, or monoglycerides. In one aspect, the vegetable oil comprises corn oil, cottonseed oil, canola oil, rapeseed oil, olive oil, palm oil, peanut oil, groundnut oil, safflower oil, sesame oil, soybean oil, sunflower oil, algae oil, almond oil (almond oil), apricot kernel oil (apricot oil), argan oil (argan oil), avocado oil, moringa oil, cashew oil (cashew oil), castor oil, grape seed oil, hazelnut oil, hemp seed oil, linseed oil, mustard oil, neem oil, palm kernel oil, pumpkin seed oil, tall oil, rice bran oil, walnut oil, combinations thereof. In another aspect, the animal fat comprises whale fat, cod liver oil, ghee, lard, tallow, derivatives thereof (e.g., yellow grease, used cooking oil, etc.), or combinations thereof.

It is envisaged that the fatty acid source may be further purified prior to subsequent processing. For example, the fatty acid source may be distilled or extracted to remove any undesirable impurities. In the alternative, the fatty acid resource may be used as is. The source of the fatty acid resource will determine whether any pre-purification steps are required. The fatty acid resource may then be pyrolyzed in the presence of an olefin using the techniques described below.

In certain aspects, the fatty acid resource may be further treated prior to pyrolysis to convert certain components present in the fatty acid resource into other species. In one aspect, the method comprises:

a. separating one or more fatty acids from a fatty acid source; and is

b. Heating the fatty acid in the presence of one or more alkenes to produce a fuel or solvent comprising one or more alkanes, alkenes, or mixtures thereof.

In one aspect, the separating step (a) involves removing or separating one or more fatty acids from a fatty acid source. Many different techniques are known in the art for the isolation and purification of fatty acids. For example, U.S. patent No. 5,917,501 discloses a method for separating fatty acids. The process involves hydrolyzing a naturally occurring lipid mixture containing phospholipids, triglycerides, and sterols to form a biphasic product containing a fatty acid phase comprised of fatty acids and sterols, and an aqueous phase comprised of water, glycerol, and glycerophosphate esters. The aqueous phase is separated from the fatty acid phase and the crude fatty acid phase is heated to convert free sterols to fatty acid sterol esters. Free fatty acids are distilled from these fatty acid sterol esters to produce purified fatty acids free of cholesterol and other sterols, as well as phosphorus compounds. In other aspects, a fatty acid resource is exposed to an acid to hydrolyze a fatty acid precursor present in the fatty acid resource to produce the corresponding free fatty acid. For example, vegetable oils are rich in triglycerides, which upon acid hydrolysis produce free fatty acids and glycerol.

In certain aspects, after the separation step, it may be desirable to produce a pure or substantially pure form of the fatty acid. The phrase "substantially pure" as used herein is defined as a fatty acid content of greater than 90% by weight. The presence of impurities may adversely affect the final composition of the fuel or solvent. For example, if sulfur, oxygen, or nitrogen compounds are present in the fatty acid prior to step (b), undesirable product performance results may occur during step (b), including high sulfur or nitrogen emissions during combustion or side reactions, such as the formation of undesirable aromatic compounds.

examples of fatty acids include, but are not limited to, butyric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, α -linolenic acid, docosahexaenoic acid, eicosapentaenoic acid, linoleic acid, arachidonic acid, oleic acid, erucic acid, fatty acids naturally derived from plant or animal sources, or combinations thereof.

Heating the free radical precursor source in the presence of one or more alkenes to produce a branched alkane, branched alkene, or combination thereof. Generally, the source of free radical precursor is introduced into a pyrolysis reactor, which is a closed vessel that can maintain high internal pressures and temperatures. In one aspect, the microreactor disclosed in U.S. patent No. 8,067,653 (incorporated by reference) may be used herein to perform the pyrolysis step.

After the source of free radical precursor has been introduced into the pyrolysis reactor, the system is purged with an inert gas (such as, for example, nitrogen or argon). Next, an olefin is introduced into the pyrolysis reactor. The term "olefin" is an organic molecule having one carbon-carbon double bond. In one aspect, the alkene is a straight or branched chain molecule consisting solely of carbon and hydrogen. The olefin may be a gas or a liquid at ambient temperature. In another aspect, the olefin is ethylene, propylene, butylene, or an isomer thereof (e.g., isobutylene), or a mixture thereof.

The amount of olefins introduced into the pyrolysis reactor can vary. In certain aspects, a molar excess of olefin relative to the free radical precursor source may be employed. For example, the molar ratio of fatty acid resources to olefin is from 1:1 to 1:5, 1:1 to 1:4, 1:1 to 1:3, or 1:1 to 1:2, where the number of moles of gas is calculated using van der Waal's equation of state for real gas. In other aspects, there may be a substantially higher amount of a source of the free radical precursor resource relative to the olefin. Thus, the relative amounts of olefin and free radical precursor sources can be correspondingly improved depending on the process conditions and reaction kinetics.

Once the pyrolysis reactor has been filled with the source of the radical precursor resource and the olefin, the reactor is internally heated to convert the radical precursor into a branched alkane or branched olefin. The temperature of the heating step may vary among different parameters. In one aspect, the temperature of the heating step is from 220 ℃ to 650 ℃, 300 ℃ to 650 ℃, 350 ℃ to 600 ℃, or 250 ℃ to 500 ℃. In another aspect, the heating step is performed at 450 ℃.

The duration of the heating step may also vary depending on the radical precursor source and the amount of olefin used and the pressure within the pyrolysis reactor. In one aspect, the pressure within the pyrolysis reactor may range from ambient pressure to 2,000psi, such as 130psi, 200psi, or 500psi, for example, and the duration of the heating step may be from seconds to 12 hours. In one aspect, the heating step is from two seconds to 8 hours. In another aspect, the heating step is performed for 2 hours. In another aspect, the reaction time and temperature are selected to maximize fatty acid feed conversion and liquid product yield while minimizing gas, aromatics, and solids formation.

By varying the reaction conditions during the conversion of the free radical precursor source to branched alkyl and branched hydrocarbyl groups, one of ordinary skill in the art can produce short or long chain alkanes/alkenes for fuels and solvents. For example, prolonged heating at high temperatures can produce short chain alkanes/alkenes that can be used as fuels. Alternatively, long chain alkanes/alkenes may be produced by one of ordinary skill in the art by reducing the heating time and temperature. If short chain alkanes or alkenes are produced, the reaction conditions can be controlled such that these products are gases (e.g., methane, propane, butane, etc.) that can be easily removed from the reactor.

The process described herein results in the formation of branched alkanes and alkenes. Without wishing to be bound by theory, the mechanism for producing branched alkanes and alkenes is depicted in fig. 1 and 2. Figure 1 shows a possible reaction scheme for forming branched olefin compounds from the reaction of alkyl radical species with ethylene (or alternatively propylene). In one aspect, the formation of branched compounds during pyrolysis of free fatty acids in the presence of ethylene is a multi-step process followed by thermal deoxygenation of the fatty acids. One possible product of fatty acid deoxygenation is the general organic compound "a" in reaction (1), wherein R represents an alkyl group. These compounds are known to undergo cleavage as described herein at 350 ℃ to 450 ℃ for between 1 to 4 hours in order to generate free radicals labeled "b" and "c", respectively. In reaction (2) the radical "b" undergoes a molecular rearrangement to produce radical "d". Reaction (3) shows that ethylene (labeled "e") reacts with radical "c", which results in the formation of branched radical "f".

Figure 2 shows a possible reaction scheme for forming branched alkane compounds from the reaction of alkyl radical species with ethylene (or alternatively propylene). One possible product of deoxygenation of the fatty acid and subsequent migration of the hydrogen to a more stable structure (common in liquid-phase free radical systems) is the general organic compound "a" in reactions (4) and (5), where R represents an alkyl group. These free radical species, described herein, formed from alkane cleavage at 350 ℃ to 450 ℃ for between 1 to 4 hours can be reacted with ethylene "b" or propylene "d" to form branched free radical alkane species "c" and "e". All end products identified by product analysis in fig. 1 and 2 can be capped by subsequent hydrogen abstraction from other molecules in the liquid phase.

In one aspect, the processes disclosed herein produce a product comprising l-olefins from C6 to C12, internal olefins from C6 to C18, n-alkanes from C6 to C19, aromatics, branched hydrocarbons, cyclic hydrocarbons, fatty acids from C4 to C18, and further mixtures of unidentified products. In this regard, the use of an olefin headspace gas may increase the proportion of desired products (such as branched hydrocarbons, for example).

In fuel formulations, branched alkanes and alkenes are preferred because they are less prone to knock phenomena (due to their high octane number) than their straight chain homologues. Furthermore, branched alkanes and alkenes find wide industrial application as solvents for non-polar chemical species. Conventionally, linear alkanes and alkenes are converted to branched isomers in industrial processes (such as reforming and isomerization) in the presence of metal catalysts. In addition, the processes described herein do not require the addition of supplemental hydrogen (i.e., the hydrogen for the reaction is added before and/or during pyrolysis of the fatty acids). The hydrogen was replenished. However, the make-up hydrogen does not include hydrogen that may be generated in situ during pyrolysis of the fatty acid in the presence of the olefin. These techniques also require pure starting materials. One significant advantage of the processes described herein is that branched alkanes can be produced without the use of any catalyst, which reduces capital and operating costs and allows the use of relatively impure feedstocks compared to conventional petroleum-based operations.

As shown below in the examples, the described process produces higher concentrations of branched alkanes and alkenes in the liquid product as compared to pyrolyzing the same fatty acids under an inert atmosphere.

In another aspect, the use of a decarboxylation catalyst may be used to facilitate the conversion of fatty acids to alkanes or alkenes. Depending on the selection of the decarboxylation catalyst, the catalyst may reduce the heating temperature and time. This may be desirable in certain circumstances, particularly if degradation or side reactions (e.g., aromatization) of the alkane/alkene are to be avoided. Examples of decarboxylation catalysts include, but are not limited to, activated alumina catalysts. The use of a decarboxylation catalyst is optional; thus, the processes described herein do not require the presence of a decarboxylation catalyst.

The processes described herein may be conducted in batch, semi-batch, or continuous modes of operation. For example, with respect to pyrolysis of free fatty acids, a continuous reactor system with unreacted acid recycle may be employed to increase the yield of desired alkane/alkene by limiting the duration and exposure of the alkane/alkene in the high temperature reactor. Carbon dioxide and small hydrocarbon products can be recovered, with the gas phase hydrocarbons being used as fuel for the reactor or other applications. When a continuous reactor system is used, process conditions can be optimized to minimize reaction temperature and time in order to maximize product yield and composition. This technique has the ability to enrich a particular product set since the reaction can be adjusted to select a preferred carbon chain length (long, short or medium). From these groups, individual chemicals can be recovered, purified, and sold as pure platform chemicals.

The methods described herein provide a number of advantages over current techniques for producing renewable biofuels. The process described herein produces higher amounts of liquid hydrocarbons, as demonstrated in the examples. As noted above, the methods described herein can be used to produce higher concentrations of branched alkanes and alkenes that are useful in modern fuel blends. These methods utilize renewable resources to produce a non-petroleum based sustainable fuel source with low levels of aromatics.

The hydrocarbons formed here are much more chemically homogeneous than other high temperature processes currently used. For example, the fuels or solvents produced herein are substantially free of aromatics, where the term "substantially free" is defined as less than 5% by weight of aromatics. It is also contemplated that no aromatic compounds are present in these fuels or solvents.

It is expected that the processes described herein will provide higher product yields than other pyrolysis technologies and will produce a fuel that is more diesel-like than biodiesel. In one aspect, the liquid product yield is from 75% to 110% by weight as fatty acid feedstock. In another aspect, the liquid product yield is from 95% to 110%, alternatively about 98% or about 107%, by weight of fatty acid feedstock. These products will not have the problems of biodiesel, as they will be oxidation stable and will have a pour point similar to conventional diesel fuels.

In one aspect, the elemental composition of the liquid product can be determined. In one aspect, the liquid product contains a higher weight ratio of carbon than the feedstock. In this aspect, the carbon content of the feedstock can be from 70% to 80% by weight carbon, from 75% to 79% by weight carbon, or can be about 76.7% by weight carbon. Further, in this aspect, the carbon content of the liquid product can be from 80% to 90% by weight carbon, from 83% to 85.5% by weight carbon, or can be about 84% by weight carbon.

In another aspect, the liquid product contains a lower weight ratio of oxygen than the feedstock. In this aspect, the oxygen content of the feedstock can be from 5% to 15% oxygen by weight, from 8% to 13% oxygen by weight, or can be about 11.3% oxygen by weight. Further, in this aspect, the oxygen content of the liquid product may be less than 5% oxygen by weight, or may be about 2.1%, about 2.8%, about 3.0%, about 3.1%, or about 3.6% oxygen by weight.

In yet another aspect, deoxygenation of the fatty acid occurs during the methods disclosed herein. The methods described herein increase the rate of decarboxylation of fatty acids when compared to conducting the same pyrolysis reaction under an inert atmosphere (e.g., nitrogen).

In one aspect, the deoxygenation rate may increase as the initial headspace pressure increases. Carbon dioxide and/or carbon monoxide is released during the process disclosed herein. Further, in this aspect, carbon dioxide production may increase as the initial headspace pressure increases. In yet another aspect, the nitrogen and sulfur content of the feedstock and the one or more liquid products is less than 10 ppm. In this regard, the feedstock and liquid product are said to be "substantially free" of nitrogen and sulfur.

Finally, lower investment costs are expected using the methods described herein when compared to competing existing biodiesel technologies. In particular, the process does not require a hydrocarbon-producing hydrogenation step which adds significant cost to the process. Furthermore, as demonstrated in the examples, the methods described herein decarboxylate free fatty acids more rapidly than other techniques, which ultimately shortens reaction time and cost.

Examples of the invention

The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the materials, articles, and methods described and claimed herein are made and evaluated, and are intended to be purely exemplary and are not intended to limit the scope of what the inventors regard as their invention. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be accounted for. Unless otherwise indicated, parts are parts by weight, temperature is in degrees celsius or at ambient temperature and pressure is at or near atmospheric pressure. There are many variations and combinations of reaction conditions, such as component concentrations, desired solvents, solvent mixtures, temperatures, pressures, and other reaction ranges and conditions that can be used to optimize the purity and yield of the product obtained from the process. Only reasonable and routine experimentation will be required to optimize such process conditions.

The laboratory methods for sample preparation, reactor components and reaction protocols, product processing, analytical procedures for chemical characterization and quantification described in U.S. patent No. 8,067,653B2 issued 11/29/2011 were used. The reaction temperature and time were selected based on previous experiments to thermally crack oleic acid (see Asomaning et al, journal of analytical and applied pyrolysis (J.anal.appl.pyrolysis), 2014, 105: 1-7). The conditions selected for this study maximize fatty acid feed conversion and liquid product yield while minimizing gas, aromatics, and solids formation. The reaction was carried out by loading the free fatty acid in a microreactor, sealing the microreactor, and purging the microreactor with the free fatty acid with nitrogen. The pressure inside the reactor at the start of the pyrolysis reaction is controlled by filling the microreactor with a gas.

Table 1 shows that from a microreactor loaded with oleic acid and nitrogen and reacted at 410 ℃ for 2 hours, it is possible to recover 81.39% of the total initial mass as a liquid product. Pyrolysis experiments conducted in the presence of short chain saturated hydrocarbons (e.g., ethane, propane) did not produce liquid yields that were statistically different from the control experiments described above. In the case of methane, the measured liquid yield is below the nitrogen base and is measured at about 76%. On the other hand, pyrolysis experiments with unsaturated short-chain hydrocarbons (e.g., ethylene and propylene) yielded substantially higher liquid yields (about 98% and 107%, respectively).

TABLE 1 liquid product yield from the pyrolysis of oleic acid in the presence of nitrogen and hydrocarbon gases (410 deg.C, 2h)

¹Gas moles calculated using the pengital-Robinson state equation.

^aValues with the same superscript letter do not differ significantly at the 95% confidence level.

Chemical characterization of the pyrolysis liquid product by GC-MS and GC-FID confirmed the liquid yield data described above and showed that higher concentrations of alkanes and alkenes compared to inert gases can be obtained by reacting oleic acid with unsaturated short chain hydrocarbons.

Figures 3 and 4 show that reacting free fatty acids in the presence of ethylene, in addition to alkanes having a carbon number of 14, systematically yields higher concentrations of both alkanes and alkenes. Figure 5 shows that these higher concentrations of alkanes and alkenes are produced using ethylene headspace gas, regardless of the initial headspace gas pressure.

Characterization of the liquid products by GC-MS and GC-FID techniques revealed that the fatty acids reacted with the unsaturated short chain hydrocarbons produced higher concentrations of branched alkanes in the liquid products than the same reactions conducted in an inert gas atmosphere. Figure 6 shows a portion of two typical GC-FID chromatograms of liquid samples of oleic acid pyrolysis products from reactions under nitrogen and ethylene headspace, respectively. Figure 6 clearly shows the presence of branched alkanes with eight carbon atoms in the case of pyrolysis of oleic acid in the presence of ethylene. The same compounds are virtually absent in the case of pyrolysis in the presence of nitrogen. Figure 7 demonstrates that using ethylene as the headspace gas results in increased yields of branched alkanes and alkenes and that this yield increases with the initial headspace pressure, while for nitrogen the yield of branched compounds remains about the same regardless of the initial headspace pressure.

Detailed analysis of a typical GC-FID chromatogram of a liquid oleic acid pyrolysis product revealed that reactions conducted in the presence of ethylene resulted in faster fatty acid deoxygenation than the same reactions conducted in a nitrogen atmosphere. Figure 8 shows a chromatogram of a typical GC-FID from the liquid product of pyrolysis of oleic acid in the presence of nitrogen and ethylene, respectively. By comparing the peak of the internal standard with the peak adjacent to the stearic acid peak (C18:0), it is immediately apparent that the feedstock is converted more rapidly in the presence of ethylene pyrolysis of oleic acid as compared to pyrolysis under an inert atmosphere.

No water/aqueous portion was observed in the liquid product obtained under all conditions. This does not mean that no water is produced. Due to the small feed mass (1g) used in this study, no water may be observed. Previous studies with larger sample sizes confirmed that the water/aqueous portion was produced during pyrolysis of the free fatty acids. The compositions of the liquid products produced under different headspace gases are provided in table 2.

TABLE 2 liquid product composition under inert and light hydrocarbon gas atmosphere at 130psi initial pressure

^a,bIf the values in the same row have the same letter, they do not have a significant difference from the nitrogen atmosphere at a 95% confidence level.

These experiments show that the efficiency and economic value of using a two-step process (hydrolysis of lipids followed by pyrolysis of fatty acids) to convert lipids to hydrocarbons can be improved by performing the second step in the presence of a short chain unsaturated hydrocarbon such as ethylene. When such species are present, the fatty acid feedstock is converted more rapidly, producing a greater proportion of liquid products in the range of valuable gasoline, diesel and jet fuels. In addition, the process described herein results in the formation of branched alkanes and alkenes, which are essential elements in modern fuel mixtures.

The elemental composition of the liquid product was determined using a Carlo Erba EA 1108 elemental analyzer at the analytical and Instrumentation Laboratory in the Chemistry Department of the university of Alberta (the analytical and Instrumentation Laboratory at the university of Chemistry of Alberta). The results are presented in table 3.

TABLE 3 elemental composition of liquid product and oleic acid feed

Calculated from the difference.

BDL: below the detection limit (10 ppm).

The results presented in table 3 show that both nitrogen and sulfur in the feed are below the detection limit of 10ppm and, therefore, the liquid product also has nitrogen and sulfur contents below this detection limit. Furthermore, these results demonstrate deoxygenation during the pyrolysis reaction, regardless of the headspace gas used. In addition, these results show an increase in deoxygenation with increasing initial headspace pressure.

As shown in fig. 9 and 10, the use of both nitrogen and ethylene as the headspace gas produced carbon monoxide and carbon dioxide.

Throughout this application, various publications are referenced. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the compounds, compositions and methods described herein.

Various modifications and changes may be made in the materials, methods, and articles described herein. Other aspects of the materials, methods, and articles described herein will be apparent from consideration of the specification and practice of the materials, methods, and articles disclosed herein. It is intended that the specification and examples be considered as exemplary.

Claims (26)

1. A method for producing a fuel or solvent comprising a branched alkane, a branched alkene, or a combination thereof, the method comprising heating a fatty acid or a salt of a fatty acid in the presence of one or more alkenes to produce the fuel or solvent, the heating being carried out in the absence of any catalyst at a temperature of from 350 ℃ to 600 ℃.

2. A method for producing a fuel or solvent comprising a branched alkane, a branched alkene, or a combination thereof from a fatty acid, the method comprising heating the fatty acid or salt of a fatty acid in the presence of one or more alkenes, the heating being carried out in the absence of any catalyst at a temperature of from 350 ℃ to 600 ℃, wherein the fatty acid is separated from a fatty acid source prior to the heating in the presence of the alkene.

3. The method of claim 2, wherein the method for separating the fatty acid from the fatty acid resource comprises (a) separating one or more triglycerides from the fatty acid resource, (b) hydrolyzing the triglycerides to produce the free fatty acid, and (c) separating the free fatty acid.

4. The method of claim 2, wherein the fatty acid resource comprises a monoglyceride, a diglyceride, a triglyceride, a free fatty acid or a salt thereof, or any combination thereof.

5. The method of claim 2, wherein the fatty acid resource comprises a vegetable oil, an animal fat, or a bio-oil.

6. The method of claim 2, wherein the fatty acid resource comprises waste cooking oil.

7. The method of claim 2, wherein the fatty acid resource comprises lipids derived from biosolids.

8. The method of claim 2, wherein the fatty acid resource comprises a lipid.

9. The method of claim 2, wherein the fatty acid resource comprises a phospholipid.

10. The method of claim 2, wherein the fatty acid resource comprises triglycerides.

11. The method of claim 5, wherein the vegetable oil comprises corn oil, cottonseed oil, canola oil, rapeseed oil, olive oil, palm oil, peanut oil, safflower oil, sesame oil, soybean oil, sunflower oil, algae oil, almond oil, apricot kernel oil, argan oil, avocado oil, moringa oil, cashew oil, castor oil, grapeseed oil, hazelnut oil, hemp oil, linseed oil, mustard oil, neem oil, palm kernel oil, pumpkin seed oil, rice bran oil, or walnut oil, tall oil, combinations thereof.

12. The method of claim 5, wherein the animal fat comprises whale fat, cod liver oil, ghee, lard, tallow, or combinations thereof.

13. The method of claim 1 or 2, wherein the fatty acid comprises a saturated fatty acid, an unsaturated fatty acid, or a combination thereof.

14. the method of claim 1 or 2, wherein the fatty acid comprises butyric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, α -linolenic acid, docosahexaenoic acid, eicosapentaenoic acid, linoleic acid, arachidonic acid, oleic acid, erucic acid, a fatty acid naturally derived from a plant or animal source, or a combination thereof.

15. The method of claim 1 or 2, wherein the fatty acid is a free fatty acid.

16. The method of claim 1 or 2, wherein the fatty acid is a salt of a free fatty acid.

17. The method of claim 1 or 2, wherein the olefin is ethylene, propylene, butene, or isomers thereof, or any combination thereof.

18. The method of claim 1 or 2, wherein the fatty acid is heated under an olefin atmosphere at a pressure of ambient to 2,000 psi.

19. The method of claim 1 or 2, wherein the heating step is performed at a temperature of from 350 ℃ to 500 ℃ for two seconds to 8 hours.

20. The method of claim 1 or 2, wherein the heating step is performed in the absence of supplemental hydrogen.

21. The method of claim 1 or 2, wherein the rate of decarboxylation of the fatty acid is greater when heated in the presence of one or more olefins when compared to the same fatty acid heated under an inert atmosphere at the same temperature and time.

22. The method of claim 21, wherein the inert atmosphere is nitrogen.

23. A fuel or solvent produced by the method of claims 1-22.

24. A method for producing branched alkanes, branched alkenes, or a combination thereof from a biomass feedstock, the method comprising heating the biomass feedstock in the presence of one or more alkenes, the heating being carried out at a temperature of from 350 ℃ to 600 ℃ in the absence of any catalyst.

25. A method for producing branched alkanes, branched alkenes, or a combination thereof from a heavy oil, the method comprising heating the heavy oil in the presence of one or more alkenes, the heating being carried out at a temperature of from 350 ℃ to 600 ℃ in the absence of any catalyst.

26. A fuel or solvent produced by the method of claim 24 or 25.