Process for preparing bio-based olefins from primary alcohols

Abstract

Propylene is an important industrial intermediate for the production of propylene oxide and polypropylene, while isobutylene is also widely used in the production of various industrially important products, such as butyl rubber. Propylene and isobutylene are both obtained by catalytic or steam cracking of fossil feedstock, and with depletion of fossil resources and / or an increase in use cost, especially in consideration of an increase in the need for both propylene and isobutylene. Development of a commercially viable process for the direct conversion of an alcohol to any material will accordingly be very significant. The present invention relates to a process for preparing lower olefins from primary alcohols. More particularly, the present invention relates to a process for the conversion of primary alcohols to lower olefins wherein the primary alcohols are obtained from renewable sources.

Description

Technical Field

[0001] The present invention relates to a process for preparing lower olefins from primary alcohols. More particularly, the present invention relates to a process for converting primary alcohols having at least one hydrogen atom attached to a carbon atom adjacent to a carbon atom bearing an alcohol group into lower olefins, wherein the primary alcohol is obtained from a renewable source. Background Art

[0002] Biomass is considered a CO2-neutral energy carrier and one of the most abundant and renewable natural resources. In recent years, biomass conversion to produce biofuels has attracted significant efforts and investments due to market conditions and in response to various government initiatives and requirements. As the availability of bioethanol increases and the cost decreases, opportunities to use bioethanol not only as a biofuel but also as a feedstock for the manufacture of various chemicals derived from renewable sources have been explored.

[0003] The most commercially advanced effort is the dehydration of bioethanol to produce ethylene, but the conversion of bioethanol to propylene and isobutylene has also been investigated. Propylene is an important industrial intermediate for the production of propylene oxide and polypropylene, while isobutylene is likewise widely used in the production of various industrially important products, such as butyl rubber. Both propylene and isobutylene are obtained by catalytic or steam cracking of fossil feedstocks, and as fossil resources become depleted and / or their cost of use increases, particularly in view of the increased demand for both propylene and isobutylene, it would accordingly be of great interest to develop commercially viable processes for the direct conversion of alcohols into either material.

[0004] Natural raw materials are substances obtained, in particular, by processing from plants or plant parts (or even animals). Raw materials from renewable sources are characterized by a significantly high proportion of carbon isotopes 14 C. By its determination, the proportion of renewable raw materials can be determined experimentally. Renewable resources differ from those obtained by chemical synthesis or petroleum processing in that they are less homogeneous. The composition of renewable resources varies greatly, since the composition of natural resources depends on factors such as the climate and region where the plant grows, the harvest season, differences between biological species and subspecies, and the type of extraction method used in the extraction (extrusion, centrifugation, filtration, distillation, cutting, pressing, etc.).

[0005] Fusel oils are formed as a byproduct of alcohol fermentation and consist of a mixture of several alcohols, which primarily include amyl alcohol along with lesser amounts of propanol, n-butanol, and isobutanol (depending on the purification method used). Depending on the carbohydrate source and the organism used in the fermentation process, the level of fusel oils is typically between 0.2%-3.0% as a relative percentage of the target alcohol produced. Fusel oils are a byproduct of alcohol fermentation. These oils produced by yeast from nitrogenous materials in an anaerobic habitat are recovered after rectification or on an intermediate plate in a tower.

[0006] Fusel oils, sometimes called "fusel oils" or "fusel alcohols", have a composition that varies depending on their origin (potatoes, sugar beets, wheat, barley, etc.). They are a mixture of 5% to 20% water, 60% to 95% alcohol (mainly composed of straight-chain or branched alkanols containing 2 to 5 carbon atoms) and impurities (furfural, ethers, fatty acids, etc.), which in extreme cases can be up to 15% of ethanol, 2-methyl 1-butanol and 3-methyl 1-butanol. Ethanol, 2-methyl 1-butanol and 3-methyl 1-butanol are useful as starting materials for the preparation of several olefins, which are used in various industries.

[0007] Some olefins (like isobutylene, isopentene) are most often used as starting materials for other products rather than as end-uses for some end-use application. Although not exhaustive, the literature discloses several uses for the olefins isobutylene and / or isopentene. These include (i) hydrocarbon resin modification (softening point / Tg / molecular weight control), (ii) fuel additives, by oligomerization (typically dimerization) for octane boosters or by etherification with methanol or ethanol, (iii) synthetic building blocks, such as precursors for dienes, flavor / fragrance enhancers, antioxidants, typically alkylphenols, or as synthons for the preparation of fine chemicals or pharmaceutical ingredients.

[0008] It is therefore an object of the present invention to produce olefins from alcohols found in renewable feedstocks.

[0009] Another object of the present invention is to produce olefins with a pMC greater than 90 using renewable raw materials, the quality and yield of which are comparable to those produced using pure raw materials.

[0010] Yet another object of the present invention is to develop a robust process which will produce olefins of high quality, higher yield and with a pMC greater than 90, regardless of the nature of the raw material used (renewable source or pure source with several impurities). Summary of the invention

[0011] Surprisingly, the above objects have been achieved by the process according to the invention.

[0012] Therefore, a first aspect of the present invention relates to a process for preparing lower olefins having 4 to 7 carbon atoms, the process comprising the following steps:

[0013] a) A stream comprising a concentration of 60-99 wt.% of linear and / or branched C5-C8 primary alcohols having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing an alcohol group is fed into a reaction vessel.

[0014] b) oxidizing the primary alcohol to the corresponding carboxylic acid, and

[0015] c) oxidative decarboxylation of the carboxylic acid to an olefin having one less carbon atom than the starting alcohol.

[0016] A second aspect of the invention relates to a process wherein the starting material, i.e., a C5-C8 primary alcohol, has a pMC greater than 90 (when measured by the method described in ASTM Standard D6866 (current version is D6866-22) which defines the concept of "modern carbon percentage" or pMC. "Bio-based" materials have a pMC of 100%.

[0017] A third aspect of the present invention relates to a process wherein a starting material, i.e., a linear and / or branched C5-C8 primary alcohol having at least one hydrogen atom attached to a carbon atom adjacent to a carbon atom bearing an alcohol group at a concentration of 60-99 wt.%, is converted into at least one lower hydrocarbon having C4-C7 carbon atoms in a yield of at least about 80 wt.% of the maximum theoretical molar yield.

[0018] Another aspect of the invention relates to a process for preparing isobutene starting from 3-methyl-1-butanol obtained from fusel oil using a combination of oxidation of the alcohol to 3-methylbutyric acid and oxidative decarboxylation to isobutene.

[0019] Although the individual steps are known reactions, they are not described for this specific substrate and they have not been combined as a method for obtaining isobutene with a pMC greater than 90 (pMC>90%). DETAILED DESCRIPTION

[0020] If a group is defined as including at least a certain number of embodiments hereinafter, this means that it also includes a group preferably consisting only of these embodiments. In addition, the terms 'first', 'second', 'third' or 'a', 'b', 'c', etc. in the specification and claims are used to distinguish between similar elements, and are not necessarily used to describe a sequential order or a chronological order. It should be understood that the terms used in this way are interchangeable where appropriate, and the embodiments of the invention claimed herein described herein can operate in other sequences except as described or shown herein. In the case where the terms 'first', 'second', 'third' or '(A)', '(B)' and '(C)' or '(a)', '(b)', '(c)', '(d)', 'i', 'ii', etc. relate to a method or use or test step, unless otherwise indicated in the application as described above or below, there is no time or time interval coherence between these steps, that is, these steps can be performed simultaneously or there can be a time interval of seconds, minutes, hours, days, weeks, months or even years between such steps.

[0021] Furthermore, ranges defined throughout this specification also include the endpoints, ie, a range of 1 to 10 means that both 1 and 10 are included in the range. For the avoidance of doubt, the applicant is entitled to any equivalents under applicable law.

[0022] In the following paragraphs, different aspects of the invention claimed herein are defined in more detail. Unless explicitly indicated to the contrary, each aspect so defined may be combined with any one or more other aspects. In particular, any feature indicated as preferred or advantageous may be combined with any one or more other features indicated as preferred or advantageous.

[0023] References throughout this specification to 'one embodiment' or 'an embodiment' mean that the specific features, structures or characteristics described in conjunction with the embodiment are included in at least one embodiment of the invention claimed herein. Therefore, the phrase 'in one embodiment' or 'in an embodiment' appearing in different places throughout this specification does not necessarily refer to the same embodiment, but may refer to the same embodiment. Further, as used hereinafter, the terms "preferably", "more preferably", "even more preferably", "most preferably" and "particularly" or similar terms are used in conjunction with optional features without limiting the possibility of alternatives. Therefore, the features introduced by these terms are optional features and are not intended to limit the scope of the claims in any way.

[0024] Furthermore, in one or more embodiments, specific features, structures, or characteristics may be combined in any suitable manner, as will be apparent to those skilled in the art from this disclosure. Furthermore, although some embodiments described herein include some but not others that are included in other embodiments, combinations of features of different embodiments are still intended to be within the scope of the invention claimed herein and to form different embodiments, as will be understood by those skilled in the art. For example, in the appended claims, any of the claimed embodiments may be used in any combination.

[0025] Further, it should be noted that the terms "at least one", "one or more" or similar expressions indicating that a feature or element may appear once or more than once will typically be used only once when introducing the corresponding feature or element. In the following, in most cases, when referring to the corresponding feature or element, the expression "at least one" or "one or more" will not be repeated, but in fact the corresponding feature or element may exist one or more than one.

[0026] The term "yield" is defined as the amount of product obtained per unit weight of raw material and can be expressed as g product / g substrate. Yield can be expressed as a percentage of theoretical yield. "Theoretical yield" is defined as the maximum amount of product that can be produced per given amount of substrate, as indicated by the stoichiometry of the metabolic pathway used to prepare the product. For example, if the theoretical yield of a typical conversion of glucose to isobutanol is 0.41 g / g, then the butanol yield from glucose of 0.39 g / g will be expressed as 95% of the theoretical yield or 95% theoretical yield.

[0027] The term "biofuel precursor" refers to an organic molecule in which all carbon contained in the molecule is derived from biomass and is converted into a precursor from raw material thermochemistry or biochemistry. The biofuel precursor itself can be a biofuel, or can be configured to be converted into a biofuel with different characteristics by chemistry or biochemistry. The biofuel precursor includes but is not limited to 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, 1-amyl alcohol, isopentanol (3-methyl-1-butanol), 3-amyl alcohol, 2-methyl-1-butanol or neopentyl alcohol.

[0028] The terms "alkene" and "olefin" are used interchangeably herein and refer to non-aromatic hydrocarbons having at least one carbon-carbon double bond.

[0029] As used herein, "atmospheric carbon" refers to carbon atoms in carbon dioxide molecules that have been free in the Earth's atmosphere recently (e.g., in the past few decades). Such carbon atoms can be determined by the ratio of specific radioactive isotopes as described herein. "Green carbon," "atmospheric carbon," "environmentally friendly carbon," "life cycle carbon," "non-fossil fuel-based carbon," "non-petroleum-based carbon," "atmospheric carbon," and "biobased carbon" are used synonymously herein.

[0030] As used herein, "fossil carbon" refers to carbon of petrochemical origin. Fossil carbon can be determined by the methods described herein. "Fossil fuel carbon," "fossil carbon," "polluted carbon," "petrochemical carbon," "petroleum carbon," and "fossil carbon" are used synonymously herein.

[0031] The term "ASTM" refers to the American Society for Testing and Materials, which defines the testing procedures and specifications for all commercially manufactured and sold petroleum products.

[0032] Fusel oil as used herein refers to a product formed as a byproduct of alcohol fermentation and consists of a mixture of several alcohols including primarily pentanol along with smaller amounts of propanol, n-butanol, and isobutanol depending on the purification method employed.

[0033] "Renewably based" or "renewable" means that the carbon content of the biofuel precursors and subsequent products comes from "new carbon" sources as measured by ASTM Test Method D 6866-05, "Determining the Biobased Content of Natural Range Materials Using Radiocarbon and Isotope Ratio Mass Spectrometry Analysis," which is incorporated herein by reference in its entirety.

[0034] method

[0035] The present invention relates to a process for preparing lower olefins having 4 to 7 carbon atoms, the process comprising the following steps:

[0036] a) feeding a stream comprising a concentration of 60-99 wt.% of linear and / or branched C5-C8 primary alcohols having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group into a reaction vessel,

[0037] b) oxidizing the primary alcohol to the corresponding carboxylic acid, and

[0038] c) oxidative decarboxylation of the carboxylic acid to an olefin having one less carbon atom than the starting alcohol.

[0039] Step a)

[0040] In step (a), the linear and / or branched C5-C8 primary alcohol has at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group.

[0041] The linear and / or branched C5-C8 primary alcohol has at least one hydrogen atom attached to the carbon atom adjacent to the carbon atom bearing the alcohol group (which is the alpha carbon atom).

[0042] In one embodiment, the linear and / or branched C5-C8 primary alcohol has at least one hydrogen atom attached to the carbon atom adjacent to the carbon atom bearing the alcohol group (which is the alpha carbon atom) and the beta carbon atom (i.e., the carbon atom attached to the first carbon atom adjacent to the carbon atom bearing the alcohol group) also has at least one hydrogen atom.

[0043] In another embodiment, the C5-C8 primary alcohol is obtained from a natural source or from a fermentation process.

[0044] In one embodiment, the C5-C8 primary alcohol is obtained from fusel oil.

[0045] Fusel Oil

[0046] Fusel oil is well known in the art and comprises a mixture of light alcohols, fatty esters, terpenes and furfural. The alcohols contained in fusel oil are primarily propanol, butanol, amyl alcohol, isopentanol and hexanol and optionally heavier straight chain alcohols such as C7 or C8 alcohols.

[0047] Fusel oils, sometimes called "fusel oils" or "fusel alcohols," have a composition that varies depending on their source (potato, beet, wheat, barley, etc., essential elements).

[0048] Fusel oils form colorless or pale yellow liquids which have a characteristic odor. They have a density of about 0.83. Their boiling point is far from constant, since they are a complex mixture of substances with widely varying boiling points. Boiling begins at about 80°C and rises to 130°C-134°C. They are insoluble in water and are usually washed with water and phase separated by sedimentation to reduce the amount of ethanol they contain by about 4% to 5%. It should be noted that fusel alcohols are natural alcohols produced directly in a distillery by biotechnology, without any intermediate chemical steps.

[0049] Fusel oil can be obtained by several methods well known to the skilled person, for example by directly removing and cooling in a distillation column. The removed fraction can be purified, for example, by extraction and decantation. Liquid / liquid extraction followed by decantation by the addition of water results in the formation of two phases. The upper phase mainly comprises amyl alcohol and butanol, which are slightly soluble in water. The different fractions of fusel oil can also be separated by using adsorbents, which are regenerated thereafter. Among the adsorbents tested, granular plant activated carbon is preferred because it can adsorb eight times its weight of fusel oil.

[0050] In one embodiment, the fusel oil contains a mixture of linear or branched C5 alcohols, C4 alcohols, or C3 alcohols.

[0051] According to a preferred embodiment, the C5 branched alcohol present in the initial composition is a mixture of isopentanol and pentanol, namely 3-methylbutan-1-ol (isopentanol) and 2-methylbutan-1-ol (pentanol).

[0052] According to a preferred embodiment, the initial composition comprises at least 30 wt.%, preferably at least 40 wt.%, more preferably at least 50 wt.%, more preferably at least 60 wt.%, even more preferably at least 70 wt.% of C5 branched alcohols based on the total weight of the composition.

[0053] C4 alcohols such as butan-1-ol and 2-methylpropan-1-ol may also be present in the initial composition. The initial composition may contain one or both of these C4 alcohols.

[0054] A C3 alcohol, such as n-propanol, may also be present in the initial composition. The initial composition may comprise 0.01 to 20 wt.% of a C3 alcohol.

[0055] Fusel oil may further contain hexanol and optionally heavier straight chain alcohols, such as C7 or C8 alcohols.

[0056] Fusel oil is a mixture of 5% to 20% water, 60% to 95% alcohol (mainly composed of straight or branched chain alkanols containing 2 to 5 carbon atoms), impurities (including but not limited to furfural, ethers, fatty acids, etc.), and these impurities can be up to 15%.

[0057] In one embodiment, the composition of fusel oil is as follows:

[0058] 5% to 40% ethanol,

[0059] 1-Propanol 1% to 8%,

[0060] 2-Propanol 0% to 1%,

[0061] 2-Methylpropanol 5% to 15%,

[0062] 1-Butanol - 0% to 1%,

[0063] 2-Methyl-1-butanol 10% to 30%,

[0064] 3-Methyl-1-butanol (isoamyl alcohol) 25% to 70%,

[0065] The combination of alkanols accounts for 100%.

[0066] In one embodiment, the C5-C8 primary alcohol is selected from 2-methyl-1-butanol (active pentanol), 3-methyl-1-butanol (isoamyl alcohol / isopentanol), n-pentanol, n-hexanol, 2-methylpentanol, n-heptanol, n-octanol, 2-ethylhexanol, or a mixture thereof.

[0067] In a preferred embodiment, the C5-C8 primary alcohol is 3-methyl-1-butanol (isoamyl alcohol).

[0068] In one embodiment, the stream obtained from fusel oil contains C5-C8 primary alcohols in a concentration in the range of 60-99 wt%, preferably in the range of 60-95 wt%, preferably in the range of 60-90 wt%, preferably in the range of 60-85 wt%, preferably in the range of 60-80 wt%, more preferably in the range of 65-80 wt%, even more preferably in the range of 70-80 wt%.

[0069] In one embodiment, the stream obtained from fusel oil contains C5-C8 primary alcohols having a pMC greater than 90 (when measured by the method described in ASTM standard D6866 (current version is D6866-22), which defines the concept of "modern carbon percentage" or pMC. Preferably, the pMC is greater than 91, preferably greater than 93, preferably greater than 95, preferably greater than 96, preferably greater than 97, more preferably greater than 98, and even more preferably greater than 99.

[0070] In one embodiment, verification that the feedstock is derived from renewable raw materials is possible, for example by 14 C. For the purposes of the present invention, a feedstock shall be deemed to be "derived from renewable raw materials" when the carbon-14 (C-14) present in the feedstock corresponds substantially (not more than 6%) to the C-14 content of atmospheric CO2 according to ASTM D6866.

[0071] The C-14 content of a material can be determined by measuring the decay of C-14 in the material via liquid scintillation. Such raw materials should preferably be considered to be derived from renewable raw materials when they have a C-14 content showing a radioactive decay of not less than 1.5 dpm / gC (decays per gram of carbon per minute), preferably 2 dpm / gC, more preferably 2.5 dpm / gC and still more preferably 5 dpm / gC.

[0072] "Renewably based" or "renewable" means that the carbon content of the biofuel precursors and subsequent products comes from "new carbon" sources as measured by ASTM Test Method D 6866-05, "Determining the Biobased Content of Natural Range Materials Using Radiocarbon and Isotope Ratio Mass Spectrometry Analysis," which is incorporated herein by reference in its entirety. This test method measures the carbon content of a sample. 14 C / 12 C isotope ratio and compared it to that in standard 100% bio-based materials 14 C / 12 The C isotope ratios are compared to give the percent biobased content of the samples. "Biobased materials" are organic materials in which the carbon comes from CO2 that was recently (on a human time scale) fixed using energy from sunlight (photosynthesis) present in the atmosphere. On land, this CO2 is captured or fixed by plant life (e.g., crops or forestry materials). In the ocean, the CO2 is captured or fixed by photosynthetic bacteria or phytoplankton. For example, a biobased material has a carbon content greater than 0. 14 C / 12 C isotope ratio. In contrast, fossil-based materials have a C isotope ratio of approximately 0 14 C / 12 C isotope ratio. The term "renewable" with respect to compounds such as alcohols or hydrocarbons (linear or cyclic alkanes / alkenes / alkynes, aromatics, etc.) refers to compounds that are produced from biomass using thermochemical methods (e.g., Fischer-Tropsch catalysts), biocatalysts (e.g., fermentation), or other methods (e.g., as described herein).

[0073] A small amount of carbon atoms in the atmospheric carbon dioxide are radioactive isotopes 14 C. When atmospheric nitrogen is bombarded by neutrons produced by cosmic rays, it causes the nitrogen to lose protons and form carbon (atomic mass 14). 14 C), which is then immediately oxidized to carbon dioxide, producing this 14 C Carbon dioxide. A small but measurable portion of atmospheric carbon exists in the form of 14CO2. Atmospheric carbon dioxide is converted into organic molecules by green plants during a process called photosynthesis. Almost all life forms on Earth depend on these organic molecules produced by green plants to generate chemical energy for growth and reproduction. Thus, the atmospheric carbon dioxide is formed in the atmosphere. 14 C eventually becomes part of all life forms and their bioproducts, enriching biomass and the organisms that feed on it. 14 C. In contrast, carbon from fossil fuels does not have the characteristic 14C:12C ratio of renewable organic molecules derived from atmospheric CO2. Furthermore, renewable organic molecules that biodegrade to CO2 do not contribute to global warming because there is no net increase in carbon emitted into the atmosphere.

[0074] The assessment of the renewable carbon content of a material can be performed by standard test methods, such as using radiocarbon and isotope ratio mass spectrometry. ASTM International (formally known as the American Society for Testing and Materials) has established a standard method for assessing the biobased content of a material. The ASTM method is designated ASTM-D6866.

[0075] Applying ASTM-D6866 to derive “biobased content” builds on the same concepts as radiocarbon dating, but does not use an age equation. 14 The analysis is performed by comparing the amount of radiocarbon present in the sample to the amount of radiocarbon in a present-day reference standard. This ratio is reported as a percentage and its unit is "pMC" (percent modern carbon). If the material being analyzed is a mixture of present-day radiocarbon and fossil carbon (which contains very low levels of radiocarbon), the pMC value obtained is directly related to the amount of biomass material present in the sample.

[0076] The C5-C8 primary alcohols used in the present invention have a pMC value of at least greater than 90, preferably a pMC value of at least greater than 95, preferably a pMC value of at least greater than 98, more preferably a pMC value of at least greater than 99, and more preferably a pMC value of at least about 100, including all values ​​and subranges therebetween.

[0077] Step b)

[0078] In step b), a linear and / or branched C5-C8 primary alcohol having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group is converted into the corresponding carboxylic acid.

[0079] The linear and / or branched C5-C8 primary alcohol has at least one hydrogen atom attached to the carbon atom adjacent to the carbon atom bearing the alcohol group (which is the alpha carbon atom).

[0080] In one embodiment, the linear and / or branched C5-C8 primary alcohol has at least one hydrogen atom attached to the carbon atom adjacent to the carbon atom bearing the alcohol group (which is the alpha carbon atom) and the beta carbon atom (i.e., the carbon atom attached to the first carbon atom adjacent to the carbon atom bearing the alcohol group) also has at least one hydrogen atom.

[0081] In one embodiment, the oxidation of the alcohol is performed using an oxidizing agent selected from oxygen, hydrogen peroxide, or nitric acid.

[0082] Preferably, the oxidant used in this step is oxygen or nitric acid. More preferably, the oxidant used is nitric acid.

[0083] Oxidation using nitric acid

[0084] In one embodiment, the concentration of nitric acid used is in the range of 30 wt.%-65 wt.%, preferably in the range of 50 wt.%-65 wt.%, more preferably in the range of 60 wt.%-65 wt.%.

[0085] In one embodiment, the weight ratio / molar ratio of the oxidizing agent (ie, nitric acid) to the weight ratio / molar ratio of the primary alcohol is in the range of 10:1, preferably 8:1, more preferably 6:1, even more preferably 5:1.

[0086] In one embodiment, the reaction is carried out at a temperature of less than 40°C, preferably the temperature is less than 35°C, more preferably the temperature is less than 30°C.

[0087] In one embodiment, when fusel oil is used as the alcohol source, the reaction is carried out at 35°C.

[0088] In one embodiment, when pure alcohol is used as the reactant, the reaction is carried out at 0°C.

[0089] In one embodiment, the reaction is carried out in the presence of a solvent.

[0090] In one embodiment, the solvent is selected from aliphatic hydrocarbons, such as hexane, heptane, octane, nonane, decane and also petroleum ether, or halogenated hydrocarbons, such as bromopropane, methyl chloride or dichloromethane, chloroform, tetrachloroethylene, aromatic hydrocarbons, such as benzene, toluene, xylene and mesitylene, aliphatic C3-C8-ethers, such as 1,2-dimethoxyethane (DME), diethylene glycol dimethyl ether (DME), diethyl ether, dipropyl ether, methyl isobutyl ether, tert-butyl methyl ether and tert-butyl ethyl ether, dimethoxymethane, dimethoxy ... Ethoxymethane, dimethylene glycol dimethyl ether, dimethylene glycol diethyl ether, trimethylene glycol dimethyl ether, trimethylene glycol diethyl ether, tetramethylene glycol dimethyl ether, alicyclic hydrocarbons such as cyclohexane and cycloheptane, alicyclic C3-C6 ethers such as tetrahydrofuran (THF), tetrahydropyran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxolane and 1,4-dioxane, 1,3,5-trioxane, short-chain ketones such as acetone, ethyl methyl ketone and isobutyl methyl ketone.

[0091] In a preferred embodiment, the solvent is dichloromethane.

[0092] In one embodiment, the oxidation of the alcohol is carried out in the presence of nitric acid, wherein the reaction is carried out for a period of time in the range of 60 min to 240 min, preferably in the range of 60 min to 180 min, more preferably in the range of 60 min to 100 min.

[0093] In one embodiment, the carboxylic acid formed is separated by distillation.

[0094] Oxidation in the presence of O2

[0095] In one embodiment, the oxidation reaction is carried out in the presence of a gas stream containing O2 as an oxidant and a heterogeneous catalyst comprising a metal catalyst.

[0096] In one embodiment, the oxidation reaction is carried out in the presence of a gas stream containing O2 as an oxidant. The oxygen can be used undiluted or diluted. The oxygen can be diluted with other inert gases like N2, Ar or CO2, for example in the form of air.

[0097] In a preferred embodiment of the invention, undiluted oxygen is used.

[0098] In one embodiment, the oxidation reaction is carried out in the presence of an O2 flow at a flow rate of 1-10 L / hour, preferably 2-8 L / hour, more preferably 3-7 L / hour, more preferably 4-6 L / hour.

[0099] In a preferred embodiment, the oxidation reaction is carried out in the presence of an O2 flow at a flow rate of 5 liters / hour.

[0100] The method according to the invention is carried out in the presence of a catalyst. The catalyst comprises at least one catalytically active metal. In the method according to the invention, the catalytically active metal may be selected from elements of groups 8, 9, 10 and 11 of the periodic table (according to the IUPAC nomenclature). Elements of groups 8, 9, 10 and 11 of the periodic table include iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, silver and gold.

[0101] In a preferred embodiment, the catalytically active metal is selected from elements from Groups 10 and 11 of the Periodic Table (according to IUPAC nomenclature).

[0102] In a preferred embodiment, the catalytically active metal is selected from elements selected from the group consisting of platinum, palladium and gold or mixtures thereof.

[0103] In a preferred embodiment of the invention, the catalytically active metal is platinum.

[0104] The catalytically active metal may be used in any form, such as unsupported or on a support. The catalytically active metal may be used in an unsupported form, such as a powder, mesh, sponge, foam or net. In a preferred embodiment, the catalytically active metal is on a support.

[0105] In one embodiment, the metal catalyst is on a support selected from activated carbon, silica or alumina. Preferably, the support is selected from activated carbon.

[0106] The catalyst may optionally contain one or more so-called promoters, which enhance the activity of the catalytically active metal. Examples of such promoters are bismuth (Bi), antimony (Sb), lead (Pb), cadmium (Cd), tin (Sn), tellurium (Te), cerium (Ce), selenium (Se) or thallium (Tl).

[0107] In a preferred embodiment, the catalyst comprises at least one promoter selected from the group consisting of bismuth (Bi), antimony (Sb), lead (Pb), cadmium (Cd), tin (Sn) and tellurium (Te). In a preferred embodiment, the catalyst comprises at least one promoter selected from the group consisting of bismuth (Bi), lead (Pb) and cadmium (Cd).

[0108] The accelerators can be used, for example, as metals, nitrates, acetates, sulfates, citrates, oxides, hydroxides or chlorides and mixtures thereof.

[0109] In case a promoter is used, a suitable molar ratio of the catalytically active metal to the promoter is in the range of 1:0.01 to 1:10, preferably 1:0.5 to 1:5, more preferably 1:0.1 to 1:3.

[0110] The promoter may, for example, be present on a support or may be added separately to the process.

[0111] The term "on a support" includes that the catalytically active metal and / or promoter may be located on the outer surface of the support and / or the inner surface of the support. In most cases, the catalytically active metal and / or promoter will be located on the outer surface of the support and the inner surface of the support.

[0112] In the case where the catalytically active metal is on a support, the catalyst comprises the catalytically active metal, the support and optionally a promoter.

[0113] In one embodiment, the reaction is carried out at a temperature in the range of 70°C to 100°C, preferably in the range of 80°C to 100°C, preferably in the range of 80°C to 95°C, preferably in the range of 80°C to 90°C, preferably in the range of 80°C to 85°C, more preferably the temperature is about 80°C.

[0114] In one embodiment, the oxidation of alcohol is carried out in the presence of an O2 gas flow, wherein the reaction is carried out for a period of time in the range of 120 min to 24 hours, preferably in the range of 120 min to 12 hours, more preferably in the range of 120 min to 8 hours, even more preferably in the range of 120 min to 240 min.

[0115] Step c)

[0116] In one embodiment, in step c), oxidative decarboxylation of the carboxylic acid to a lower olefin having C4-C7 carbon atoms is carried out.

[0117] In one embodiment, the oxidative decarboxylation is performed in the presence of a homogeneous catalyst, wherein the homogeneous catalyst comprises at least one metal or a salt or complex thereof and a ligand.

[0118] In one embodiment, the at least one metal is selected from nickel, palladium, or platinum. Preferably, the metal is palladium.

[0119] In one embodiment, at least one metal or its salt or complex is selected from PdCl2, tetrakis(triphenylphosphine)palladium, dichlorobis(triphenylphosphine)palladium, tris(dibenzylideneacetone)dipalladium [Pd2(dba)3], bis(dibenzylideneacetone)dipalladium [Pd(dba)2], palladium acetate, dichloro(1,5-cyclooctadiene)palladium and bis[cinnamylpalladium(II)] chloride.

[0120] Preferably, the metal salt is PdCl2.

[0121] In one embodiment, the homogeneous catalyst comprises a ligand selected from the group consisting of 5-(di-tert-butylphosphino)-1',3',5'-triphenyl-1'H-1,4'-bipyrazole, bis(2-methyl-2-propyl)(2',4',6'-triisopropyl-3,6-dimethoxy-2-biphenyl)phosphine, dicyclohexyl(2',4',6'-triisopropyl-3,6-dimethoxy-[1,1'-biphenyl]-2-yl)phosphine, bis(2-methyl-2-propyl)(2',4',6'-triisopropyl-2-biphenyl)phosphine, di-(1-adamantyl)-2-morpholinophenylphosphine, tributylphosphine, butyldi-1-adamantylphosphine, (5-diphenylphosphino-9-yl)phosphine, ,9-dimethylxanthene-4-yl)-diphenylphosphine, (R)-1-[(SP)-2-(diphenylphosphino)ferrocenyl]ethyldicyclohexylphosphine, dicyclohexyl-[2-[2,6-di(propan-2-yloxy)phenyl]phenyl]phosphine, bis[5-(di(1-adamantyl)phosphino)-1′,3′,5′-triphenyl-1′H-[1,4′]bipyrazole, trimethylphosphine, triethylphosphine, tripropylphosphine, triisopropylphosphine, tributylphosphine, tricyclohexylphosphine, trimethylphosphine, triethylphosphite, tripropylphosphite, triisopropylphosphite, tributylphosphite, tricyclohexylphosphite, triphenylphosphine, tri(o-tolyl)phosphine, triisopropylphosphine, tricyclohexylphosphite, 2,2'-bis( 1,2-bis(dimethylphosphino)ethane, 1,2-bis(diethylphosphino)ethane, 1,2-bis(dipropylphosphino)ethane, 4,5-bis(diphenylphosphino)-9,9-dimethyl-xanthene (xant-phos), 1,1'-bis(diphenylphosphino)ferrocene (dppf), bis(2-(diphenyl-phosphino)phenyl)ether [DPE-phos], 1,2-bis(diisopropylphosphino)ethane, 1,2-bis-(dibutylphosphino)ethane, 1,2-bis(dicyclohexylphosphino)ethane, 1,3-bis(diisopropylphosphino)propane, 1,3-bis(dicyclohexylphosphino)propane, 1,4- Bis(diisopropyl-phosphino)butane, 1,4-bis(dicyclohexylphosphino)butane, 1,4-bis(diphenylphosphino)-butane (bppb), 2,4-bis(dicyclohexylphosphino)pentane and 1,1'-bis(diphenylphosphino)ferrocene (dppf), triphenylphosphine (PPh3), Xantphos ((9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphine)), SPANphos (4,4,4',4',6,6'-hexamethyl-3,3',4,4'-tetrahydro-2,2'-spirobi[[1]benzopyran]-8,8'-diyl)bis(diphenylphosphine)), 2,2'-bis-(diphenylphosphino)-benzophenone.

[0122] Preferably, the ligand is selected from bis(2-(diphenyl-phosphino)phenyl)ether [DPE-phos], triphenylphosphine (PPh3), Xantphos ((9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphine)), SPANphos (4,4,4′,4′,6,6′-hexamethyl-3,3′,4,4′-tetrahydro-2,2′-spirobi[[1]benzopyran]-8,8′-diyl)bis(diphenylphosphine)), 2,2′-bis-(diphenylphosphino)-benzophenone.

[0123] More preferably, the ligand is bis(2-(diphenyl-phosphino)phenyl)ether [DPE-phos].

[0124] In one embodiment, the homogeneous catalyst is used in a concentration of less than 5 mol.%, preferably less than 3 mol%, more preferably less than 2 mol%.

[0125] In one embodiment, the catalyst is used in a concentration ranging from 0.1 mol.% to 2 mol.% based on the carboxylic acid in step (b).

[0126] In one embodiment, the molar ratio of the ligand to the metal catalyst or its salt or complex is in the range of 5:1 to 1:1, preferably the ratio of the ligand to the metal catalyst or its salt or complex is 2:1.

[0127] In one embodiment, step c) is performed in the presence of anhydride.

[0128] In one embodiment, the decarboxylation of the acid to a lower olefin having C4-C7 carbon atoms in step c) is carried out in the presence of a carboxylic anhydride which is different from the coupling product of the carboxylic acid obtained in step b).

[0129] In another embodiment, the anhydride is selected from acetic anhydride, propionic anhydride, butyric anhydride, or maleic anhydride. Preferably, the anhydride is acetic anhydride.

[0130] In one embodiment, step (c) is carried out at a reaction temperature of less than 150°C, preferably less than 145°C, preferably in the range of 130°C to 150°C, more preferably in the range of 130°C to 145°C.

[0131] In another embodiment, step c) is performed for a time period ranging from 60 min to 300 min, preferably from 100 min to 300 min, more preferably from 120 min to 240 min, more preferably from 60 to 240 min.

[0132] In one embodiment, the olefin having C4-C7 carbon atoms is selected from 1-butene, isobutylene, 1-pentene, isopentene, 1-hexene, 2-hexene, 3-hexene, 4-methyl-1-pentene, preferably the olefin is isobutylene.

[0133] In one embodiment of the present invention, the method comprises the following steps:

[0134] a) A stream comprising a concentration of 60-99 wt.-% of linear and / or branched C5-C8 primary alcohols having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group is fed into a reaction vessel.

[0135] b) oxidizing the primary alcohol to the corresponding carboxylic acid, and

[0136] c) oxidative decarboxylation of the carboxylic acid to an olefin having one less carbon atom than the starting alcohol,

[0137] Wherein the concentration of 60-99wt.% of straight chain or branched C 5- The C8 alcohol is converted to at least one lower hydrocarbon having C4 to C7 carbon atoms in a yield of at least about 80 wt.% of the maximum theoretical molar yield.

[0138] In one embodiment of the present invention, the method comprises the following steps:

[0139] a) feeding a stream comprising a concentration of 60-99 wt.% of linear and / or branched C5-C8 primary alcohols having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group into a reaction vessel,

[0140] b) oxidizing the primary alcohol to the corresponding carboxylic acid in the presence of an oxidizing agent selected from nitric acid or O2, and carrying out the oxidation of the alcohol in the presence of a heterogeneous material comprising platinum, and

[0141] c) oxidative decarboxylation of the carboxylic acid to an olefin having one less carbon atom than the starting alcohol, wherein the oxidative decarboxylation is carried out in the presence of a homogeneous catalyst in a concentration of less than 5 mol.%, preferably less than 3 mol.%, more preferably less than 2 mol.%.

[0142] Wherein the concentration of 60-99wt.% of straight chain or branched C 5- The C8 alcohol, which is isoamyl alcohol, is converted to at least one lower hydrocarbon having C4-C7 carbon atoms, which is isobutylene, in a yield of at least about 80 wt.% of the maximum theoretical molar yield.

[0143] Advantages of the Invention

[0144] 1. The process according to the invention enables the preparation of olefins in high yields and with high selectivity under mild conditions (both temperature and pressure), while requiring only moderate to low amounts of catalyst.

[0145] 2. The process can be carried out without the use of organic solvents or with low amounts of organic solvents, thus avoiding or minimizing waste streams with environmental impact.

[0146] 3. Another advantage of the process of the present invention is that the desired olefins are obtained in high concentrations in the reaction mixture, thereby minimizing downstream separation steps.

[0147] 4. The process of the present invention enables the formation of olefins in comparable yields and purity, regardless of the source of the primary alcohol used as the starting material. (Pure primary alcohol or alcohol isolated from fusel oil). Therefore, impurities in the starting material do not hamper the yield and purity of the final product (olefins in this case).

[0148] 5. The process according to the present invention uses readily available reagents and thereby reduces the overall cost of the process, thereby making it an industrially viable process which can be easily scaled up.

[0149] 6. The process according to the invention uses 3-methyl-1-butanol from fusel oil as starting material and uses a combination of oxidation of the alcohol to 3-methylbutyric acid and oxidative decarboxylation to isobutene. Although the individual steps are known reactions, they are not described for this specific substrate and they are not combined as a process to obtain olefins (isobutene) with pMC>90% and can therefore be considered inventive.

[0150] 7. The olefin (isobutylene) obtained will also have a pMC value greater than 90, which can be inferred from the fact that the input stream comprising linear or branched C5-C8 primary alcohols has a pMC value greater than 90 (which is obtained in natural sources - i.e. fusel oil).

[0151] Example

[0152] Hereinafter, a list of examples is provided to further illustrate the present disclosure without intending to limit the present disclosure to the specific examples listed below.

[0153] 1. A method for preparing lower olefins having 4 to 7 carbon atoms, the method comprising the following steps:

[0154] a) A stream comprising a concentration of 60-99 wt.% of linear and / or branched C5-C8 primary alcohols having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing an alcohol group is fed into a reaction vessel.

[0155] b) oxidizing the primary alcohol to the corresponding carboxylic acid, and

[0156] c) oxidative decarboxylation of the carboxylic acid to an olefin having one less carbon atom than the starting alcohol.

[0157] 2. The method according to embodiment 1, wherein the stream comprising linear and / or branched C5-C8 primary alcohols having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group has a pMC of at least greater than 90, preferably a pMC value of at least greater than 95, preferably a pMC value of at least greater than 98, more preferably a pMC value of at least greater than 99, more preferably a pMC value of at least about 100, including all values ​​and subranges therebetween, when measured by the method as described in ASTM Standard D6866.

[0158] 3. The method according to embodiment 2, wherein the stream comprising linear or branched C5-C8 primary alcohols having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group is obtained from a natural source.

[0159] 4. The method according to embodiment 2, wherein the stream comprising linear or branched C5-C8 primary alcohols having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group is obtained from a fermentation process.

[0160] 5. The method according to embodiment 1, wherein the stream comprising linear and / or branched C5-C8 primary alcohols has at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group, which is an alpha carbon atom.

[0161] 6. A method according to embodiment 5, wherein the stream comprising linear and / or branched C5-C8 primary alcohols has at least one hydrogen atom attached to the carbon atom adjacent to the carbon atom bearing the alcohol group, which is the alpha carbon atom, and the beta carbon atom (i.e., the carbon atom attached to the first carbon atom adjacent to the carbon atom bearing the alcohol group) also has at least one hydrogen atom.

[0162] 7. The method according to any one of embodiments 1 to 6, wherein the straight-chain or branched C5-C8 primary alcohol having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group is selected from 2-methyl-1-butanol (active pentanol), 3-methylbutan-1-ol (isopentanol), n-pentanol, n-hexanol, 2-methylpentanol, n-heptanol, n-octanol, 2-ethylhexanol.

[0163] 8. The method of any one of embodiments 1 to 7, wherein the linear or branched C5-C8 primary alcohol having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group is 3-methylbutan-1-ol (isoamyl alcohol).

[0164] 9. A method according to any one of embodiments 1 to 8, wherein the stream comprises a concentration in the range of 60 wt.%-99 wt.%, preferably in the range of 60 wt.%-95 wt.%, preferably in the range of 60 wt.%-90 wt.%, preferably in the range of 60 wt.%-85 wt.%, preferably in the range of 60 wt.%-80 wt.%, more preferably in the range of 65 wt.%-80 wt.%, even more preferably in the range of 70 wt.%-80 wt.%. of a straight or branched C5-C8 primary alcohol having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group.

[0165] 10. The method according to embodiment 1, wherein in step (b), the oxidation of the primary alcohol is carried out using an oxidizing agent selected from O2, H2O2 or nitric acid.

[0166] 11. The method according to embodiment 10, wherein in step (b), the oxidation of the primary alcohol is carried out using nitric acid.

[0167] 12. The method according to embodiment 11, wherein in step (b), the oxidation of the primary alcohol is carried out using nitric acid having a concentration in the range of 30 wt.%-65 wt.%, preferably in the range of 50 wt.%-65 wt.%, more preferably in the range of 60 wt.%-65 wt.%.

[0168] 13. The method according to any one of embodiments 10 to 11, wherein in step (b), the oxidation of the primary alcohol is carried out at a reaction temperature of less than 40°C, preferably the temperature is less than 35°C, more preferably the temperature is less than 30°C.

[0169] 14. The process according to any one of embodiments 10 to 11, wherein in step (b), the oxidation of the primary alcohol is carried out in the presence of nitric acid, wherein the reaction is carried out for a time period in the range of 60 min to 240 min, preferably in the range of 60 min to 180 min, more preferably in the range of 60 min to 100 min.

[0170] 15. A method according to embodiment 10, wherein in step (b), the oxidation of the primary alcohol is carried out in the presence of a gas flow containing O2 as an oxidant and a heterogeneous material comprising a metal catalyst selected from the group consisting of platinum, palladium, gold or a mixture thereof, and the gas flow has a flow rate of 1-10 liters / hour, preferably 2-8 liters / hour, more preferably 3-7 liters / hour, and more preferably 4-6 liters / hour.

[0171] 16. The method of embodiment 15, wherein in step (b), the oxidation of the alcohol is carried out in the presence of a heterogeneous material comprising platinum.

[0172] 17. The method according to embodiments 15 to 16, wherein the metal catalyst is supported on an inert carrier, wherein the carrier is selected from activated carbon, silica or alumina optionally doped with bismuth, cadmium or lead.

[0173] 18. The process of any one of embodiments 15 to 17, wherein the oxidation of the alcohol is carried out at a reaction temperature in the range of 80°C to 100°C, preferably in the range of 80°C to 95°C, preferably in the range of 80°C to 90°C, preferably in the range of 80°C to 85°C, more preferably the temperature is about 80°C.

[0174] 19. The method according to any one of embodiments 15 to 17, wherein the oxidation of the primary alcohol is carried out in the presence of an O2 gas stream, wherein the reaction is carried out for a time period in the range of 120 min to 24 hours, preferably in the range of 120 min to 12 hours, more preferably in the range of 120 min to 8 hours, even more preferably in the range of 120 min to 240 min.

[0175] 20. The process according to embodiment 1, wherein in step (c), the oxidative decarboxylation of the acid to a lower olefin having C4-C7 carbon atoms is carried out in the presence of a homogeneous catalyst.

[0176] 21. The method of embodiment 20, wherein the homogeneous catalyst comprises at least one metal or a salt or complex thereof, and a ligand.

[0177] 22. The method according to embodiment 21, wherein the at least one metal is selected from nickel, palladium or platinum.

[0178] 23. The method according to embodiment 22, wherein the at least one metal is palladium.

[0179] 24. The method of any one of embodiments 21 to 23, wherein the at least one metal or salt or complex thereof is selected from PdCl2, tetrakis(triphenylphosphine)palladium, dichlorobis(triphenylphosphine)palladium, tris(dibenzylideneacetone)dipalladium [Pd2(dba)3], bis(dibenzylideneacetone)dipalladium [Pd(dba)2], palladium acetate, dichloro(1,5-cyclooctadiene)palladium, and bis[cinnamylpalladium(II)] chloride.

[0180] 25. The method of embodiment 21, wherein the homogeneous catalyst comprises a ligand selected from the group consisting of: 5-(di-tert-butylphosphino)-1',3',5'-triphenyl-1'H-1,4'-bipyrazole, bis(2-methyl-2-propyl)(2',4',6'-triisopropyl-3,6-dimethoxy-2-biphenyl)phosphine, dicyclohexyl(2',4',6'-triisopropyl-3,6-dimethoxy-[1,1'-biphenyl]-2-yl)phosphine, bis(2-methyl-2-propyl)(2',4',6'-triisopropyl-2-biphenyl)phosphine, di-(1-adamantyl)-2-morpholinophenylphosphine, tributylphosphine, butyldi-1-adamantylphosphine 、(5-diphenylphosphine-9,9-dimethylxanthene-4-yl)-diphenylphosphine、(R)-1-[(SP)-2-(diphenylphosphino)ferrocenyl]ethyldicyclohexylphosphine、dicyclohexyl-[2-[2,6-di(propan-2-yloxy)phenyl]phenyl]phosphine、bis[5-(di(1-adamantyl)phosphino)-1′,3′,5′-triphenyl-1′H-[1,4′]bipyrazole、trimethylphosphine、triethylphosphine、tripropylphosphine、triisopropylphosphine、tributylphosphine、tricyclohexylphosphite、trimethylphosphine、triethylphosphite、tripropylphosphite、triisopropylphosphite、tributylphosphite、tricyclohexylphosphite、triphenylphosphine、tri(o-tolyl)phosphine、triisopropylphosphine , tricyclohexylphosphine, 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP), 1,2-bis(dimethylphosphino)ethane, 1,2-bis(diethylphosphino)ethane, 1,2-bis(dipropylphosphino)ethane, 4,5-bis(diphenylphosphino)-9,9-dimethyl-xanthene (xant-phos), 1,1'-bis(diphenylphosphino)ferrocene (dppf), bis(2-(diphenyl-phosphino)phenyl)ether [DPE-phos], 1,2-bis(diisopropylphosphino)ethane, 1,2-bis-(dibutylphosphino)ethane, 1,2-bis(dicyclohexylphosphino)ethane, 1,3-bis(diisopropylphosphino)propane, 1,3- Bis(dicyclohexylphosphino)propane, 1,4-bis(diisopropyl-phosphino)butane, 1,4-bis(dicyclohexylphosphino)butane, 1,4-bis(diphenylphosphino)-butane (bppb), 2,4-bis(dicyclohexylphosphino)pentane and 1,1'-bis(diphenylphosphino)ferrocene (dppf), triphenylphosphine (PPh3), Xantphos ((9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphine)), SPANphos (4,4,4',4',6,6'-hexamethyl-3,3',4,4'-tetrahydro-2,2'-spirobi[[1]benzopyran]-8,8'-diyl)bis(diphenylphosphine)), 2,2′-bis-(diphenylphosphino)-benzophenone, preferably, the ligand is selected from bis(2-(diphenyl-phosphino)phenyl)ether [DPE-phos], triphenylphosphine (PPh3), Xantphos ((9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphine)), SPANphos (4,4,4′,4′,6,6′-hexamethyl-3,3′,4,4′-tetrahydro-2,2′-spirobi[[1]benzopyran]-8,8′-diyl)bis(diphenylphosphine)), 2,2′-bis-(diphenylphosphino)-benzophenone, more preferably the ligand is bis(2-(diphenyl-phosphino)phenyl)ether [DPE-phos]. ,

[0181] 26. The process according to any one of embodiments 20 to 25, wherein in step (c), the homogeneous catalyst is used in a concentration of less than 5 mol.%, preferably less than 3 mol%, more preferably less than 2 mol%.

[0182] 27. The method of any one of embodiments 20 to 25, wherein in step (c), the molar ratio of the ligand to the metal catalyst or its salt or its complex is 5:1 or 3:1; preferably the ratio is 2:1.

[0183] 28. The process according to any one of embodiments 20 to 25, wherein in step (c), the decarboxylation of the acid to a lower hydrocarbon having C4-C7 carbon atoms is carried out in the presence of a carboxylic acid anhydride (anhydride) different from the coupling product of the carboxylic acid obtained in step b).

[0184] 29. The method of embodiment 26, wherein the anhydride is selected from acetic anhydride, propionic anhydride, butyric anhydride, or maleic anhydride.

[0185] 30. The method of embodiment 27, wherein the anhydride is acetic anhydride.

[0186] 31. The method according to embodiments 20 to 29, wherein in step (c), the decarboxylation of the acid to lower hydrocarbons having C4-C7 carbon atoms is carried out at a reaction temperature of less than 150°C, preferably less than 145°C, preferably in the range of 130°C to 150°C, more preferably in the range of 130°C to 145°C.

[0187] 32. The method according to embodiments 20 to 30, wherein in step (c), the decarboxylation of the acid to lower hydrocarbons having C4-C7 carbon atoms is carried out for a time period ranging from 60 min to 300 min, preferably from 100 min to 300 min, more preferably from 120 min to 240 min, more preferably from 60 to 240 minutes.

[0188] 33. The method according to embodiments 20 to 31, wherein the lower hydrocarbon having C4-C7 carbon atoms is selected from 1-butene, isobutylene, 1-pentene, isopentene, 1-hexene, 2-hexene, 3-hexene, 4-methyl-1-pentene.

[0189] 34. The method according to embodiment 33, wherein the lower hydrocarbon having C4-C7 carbon atoms is isobutylene.

[0190] 35. The method of any one of embodiments 1 to 33, wherein a linear or branched C5-C8 primary alcohol having at least one hydrogen atom attached to a carbon atom adjacent to a carbon atom bearing an alcohol group at a concentration of 60-99 wt.% is converted to at least one lower hydrocarbon having C4-C7 carbon atoms in a yield of at least about 80 wt.% of the maximum theoretical molar yield.

[0191] 36. The method of any one of embodiments 1 to 35, wherein the method comprises the steps of:

[0192] a) feeding a stream comprising a concentration of 60-99 wt.-% of a linear or branched C5-C8 primary alcohol having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group into a reaction vessel,

[0193] b) oxidizing the primary alcohol to the corresponding carboxylic acid, and

[0194] c) oxidative decarboxylation of the carboxylic acid to an olefin having one less carbon atom than the starting alcohol,

[0195] wherein a straight-chain or branched C5-C8 primary alcohol having a concentration of 60-99 wt.% is converted into at least one lower hydrocarbon having C4-C7 carbon atoms in a yield of at least about 80 wt.% of the maximum theoretical molar yield.

[0196] Examples

[0197] The present invention is further illustrated by the following non-limiting examples.

[0198] Material

[0199] Crude / isolated from fusel oil - Isoamyl alcohol was obtained from Crop Energies AG.

[0200] The composition of the fusel oil used is as follows:

[0201]

[0202] Example 1: Oxidation of pure isoamyl alcohol using O2

[0203]

[0204] Isoamyl alcohol (10 g) was mixed with water (90 g). Catalyst Pt / C (3 g, 5 wt.-% Pt on C, 58 wt.-% water) was added and the mixture was stirred at 80° C. under an oxygen atmosphere for 24 h. After cooling to ambient temperature, the mixture was diluted with ethyl acetate, filtered and the aqueous phase was extracted with ethyl acetate. The solvent was removed in vacuo. Yield: 85%

[0205] Example 2: Oxidation of pure isoamyl alcohol using HNO3

[0206] Nitric acid (55 g, 65%) was cooled to 0°C using an ice bath. Isoamyl alcohol (10 g) was added dropwise over 45 min while stirring under nitrogen. After the addition was complete, water (50 mL) was added and the mixture was stirred for 10 min. The biphasic mixture was diluted with dichloromethane (100 mL) and stirred for 30 min. The phases were separated and the organic phase was dried over sodium sulfate. The product isovaleric acid was isolated by distillation (190°C oil bath, 120°C top temperature). Yield: 94%

[0207] Example 3: Oxidation of fusel oil (containing 70% isoamyl alcohol) using HNO3

[0208] Nitric acid (57 g, 65%) was tempered to 35°C in an oil bath. Fusel oil (14.5 g, containing 70% isoamyl alcohol) was added dropwise over 45 min while stirring under nitrogen. After the addition was complete, water (50 mL) was added and the mixture was stirred for 10 min. The biphasic mixture was diluted with dichloromethane (100 mL) and water (100 mL) and stirred for 30 min. The phases were separated and the organic phase was dried over sodium sulfate. The product isovaleric acid was isolated by distillation (200°C oil bath, 170°C top temperature). Yield: 84%

[0209] Example 4: Decarboxylation of isovaleric acid to isobutylene

[0210] Under nitrogen atmosphere, isovaleric acid (1.87 g) was mixed with PdCl2 (1.76 mol%) and bis[(diphenylphosphino)phenyl]ether (DPE-Phos, 3.53 mol%). DMPU (N,N′-dimethylpropyleneurea, 36 g) was added, and acetic anhydride (2.53 g) was slowly added while stirring. After stirring at ambient temperature for 15 min, the reaction mixture was heated to 140° C. for 4 h. While heating, PdCl2 was completely dissolved, as indicated by the yellow coloration of the solution.

[0211] The end of the reaction is indicated by the red coloration of the reaction mixture. The isobutylene formed is collected using a gas collector for analysis and condensed in toluene. Yield: 85%-87%

[0212] Example 5: Oxidation of pure 2-methyl-1-butanol using HNO3

[0213]

[0214] Nitric acid (5.5 g, 65%) was cooled to 0°C using an ice bath. While stirring under nitrogen, 2-methyl-1-butanol (1 g) was added dropwise over 15 min. After the addition was complete, water (50 mL) was added and the mixture was stirred for 10 min. The biphasic mixture was diluted with dichloromethane (15 mL) and stirred for 30 min. The phases were separated and the organic phase was dried over sodium sulfate. The product 2-methyl-1-butyric acid was isolated by distillation (190°C oil bath, 120°C top temperature). Yield: 90%.

[0215] Example 6: Decarboxylation of 2-methyl-1-butyric acid to butene isomers

[0216] Under nitrogen atmosphere, 2-methyl-1-butyric acid (0.5 g) obtained in Example 5 was mixed with PdCl2 (1.76 mol%) and bis[(diphenylphosphino)phenyl]ether (DPE-Phos, 3.53 mol%). DMPU (N,N′-dimethylpropyleneurea, 9.5 g) was added, and acetic anhydride (0.68 g) was slowly added under stirring. After stirring at ambient temperature for 15 min, the reaction mixture was heated to 140° C. for 4 h. While heating, PdCl2 was completely dissolved, indicated by the yellow coloration of the solution.

[0217] The end of the reaction is indicated by the red coloration of the reaction mixture. The butene isomers formed are collected using a gas collector for analysis and condensed in toluene. Yield: 81%, containing 1-butene, cis-butene and trans-butene in a ratio of 6:2:1.

[0218] Table 1:

[0219] Isoamyl alcohol source Acid % (Product of step b)) Isobutylene % (product of step c)) Pure 85-94 85 Separation from crude fusel oil 84 85-87

Claims

1. A method for preparing lower olefins having 4 to 7 carbon atoms, the method comprising the following steps: a) feeding a stream comprising a concentration of 60-99 wt.% of linear and / or branched C5-C8 primary alcohols having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group into a reaction vessel, b) oxidizing the primary alcohol to the corresponding carboxylic acid, and c) oxidative decarboxylation of the carboxylic acid to an olefin having one less carbon atom than the starting alcohol.

2. The method according to claim 1, wherein: The stream comprising linear and / or branched C5-C8 primary alcohols having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group has a pMC greater than 90 when measured by the method as described in ASTM Standard D6866.

3. The method according to claim 2, wherein: The stream comprising linear and / or branched C5-C8 primary alcohols having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group is obtained from a natural source or from a fermentation process.

4. The method according to any one of claims 1 to 3, wherein: The straight-chain or branched C5-C8 primary alcohol having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group is selected from 2-methyl-1-butanol (active pentanol), 3-methylbutan-1-ol (isoamylalcohol / isopentanol), n-pentanol, n-hexanol, 2-methylpentanol, n-heptanol, n-octanol, or 2-ethylhexanol.

5. The method according to any one of claims 1 to 4, wherein: The linear or branched C5-C8 primary alcohol having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group is 3-methylbutan-1-ol (isoamyl alcohol).

6. The method according to claim 1, wherein: In step (b), oxidation of the primary alcohol is carried out using an oxidizing agent selected from O2, H2O2 or nitric acid.

7. The method according to claim 6, wherein: In step (b), oxidation of the primary alcohol is carried out using nitric acid having a concentration in the range of 40-65 wt.%.

8. The method according to claim 6, wherein: In step (b), the oxidation of the primary alcohol is carried out in the presence of a gas stream containing O2 as oxidant and a heterogeneous catalyst comprising a metal catalyst selected from platinum, palladium, gold or a mixture thereof.

9. The method according to claim 8, wherein: In step (b), the oxidation of the primary alcohol is carried out in the presence of platinum.

10. The method according to claim 1, wherein: In step (c), oxidative decarboxylation of the acid to a lower olefin having C4 to C7 carbon atoms is carried out in the presence of a homogeneous catalyst.

11. The method according to claim 10, wherein: The homogeneous catalyst comprises at least one metal or a salt or complex thereof, and a ligand.

12. The method according to claim 11, wherein: The at least one metal is selected from nickel, palladium, or platinum.

13. The method according to any one of claims 11 to 12, wherein: The at least one metal or its salt or complex is selected from PdCl2, tetrakis(triphenylphosphine)palladium, dichlorobis(triphenylphosphine)palladium, tris(dibenzylideneacetone)dipalladium [Pd2(dba)3], bis(dibenzylideneacetone)dipalladium [Pd(dba)2], palladium acetate, dichloro(1,5-cyclooctadiene)palladium, or bis[cinnamylpalladium(II)] chloride.

14. The method according to claim 11, wherein: The homogeneous catalyst comprises a ligand selected from the group consisting of 5-(di-tert-butylphosphino)-1',3',5'-triphenyl-1'H-1,4'-bipyrazole, bis(2-methyl-2-propyl)(2',4',6'-triisopropyl-3,6-dimethoxy-2-biphenyl)phosphine, dicyclohexyl(2',4',6'-triisopropyl-3,6-dimethoxy-[1,1'-biphenyl]-2-yl)phosphine, bis(2-methyl-2-propyl)(2',4',6'-triisopropyl-2-biphenyl)phosphine, di-(1-adamantyl)-2-morpholinophenylphosphine, tris(2',4',6'-triisopropyl-3,6-dimethoxy-[1,1'-biphenyl]-2-yl)phosphine, Butyl phosphine, butyl di-1-adamantyl phosphine, (5-diphenylphosphine-9,9-dimethylxanthene-4-yl)-diphenylphosphine, (R)-1-[(SP)-2-(diphenylphosphino)ferrocenyl]ethyldicyclohexylphosphine, dicyclohexyl-[2-[2,6-di(propan-2-yloxy)phenyl]phenyl]phosphine, bis[5-(di(1-adamantyl)phosphino)-1′,3′,5′-triphenyl-1′H-[1,4′]bipyrazole, trimethylphosphine, triethylphosphine, tripropylphosphine, triisopropylphosphine, tributylphosphine, tricyclohexylphosphine, trimethylphosphine, phosphorous acid triethyl ester, tripropyl phosphite, triisopropyl phosphite, tributyl phosphite, tricyclohexyl phosphite, triphenylphosphine, tri(o-tolyl)phosphine, triisopropylphosphine, tricyclohexylphosphine, 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP), 1,2-bis(dimethylphosphino)ethane, 1,2-bis(diethylphosphino)ethane, 1,2-bis(dipropylphosphino)ethane, 4,5-bis(diphenylphosphino)-9,9-dimethyl-xanthene (xant-phos), 1,1'-bis(diphenylphosphino)ferrocene (dppf), bis(2-( diphenyl-phosphino)phenyl) ether [DPE-phos], 1,2-bis(diisopropylphosphino)ethane, 1,2-bis-(dibutylphosphino)ethane, 1,2-bis(dicyclohexylphosphino)ethane, 1,3-bis(diisopropyl-phosphino)propane, 1,3-bis(dicyclohexylphosphino)propane, 1,4-bis(diisopropyl-phosphino)butane, 1,4-bis(dicyclohexylphosphino)butane, 1,4-bis(diphenylphosphino)-butane (bppb), 2,4-bis(dicyclohexylphosphino)pentane, or 1,1'-bis(diphenylphosphino)ferrocene (dppf).

15. The method according to any one of claims 10 to 14, wherein: In step (c), the decarboxylation of the acid to a lower olefin having C4-C7 carbon atoms is carried out in the presence of a carboxylic anhydride different from the coupling product of the carboxylic acid obtained in step b).

16. The method according to claim 15, wherein: The carboxylic anhydride is selected from acetic anhydride, propionic anhydride, butyric anhydride, or maleic anhydride.

17. The method according to claims 10 to 14, wherein: The catalyst is used in a concentration ranging from 0.1 mol.% to 2 mol.%, based on the carboxylic acid in step (b).

18. The method according to claims 1 to 17, wherein: The lower olefin having C4-C7 carbon atoms is selected from 1-butene, isobutene, 1-pentene, 3-methyl-1-butene, hexene, 2-hexene, 3-hexene or 4-methyl-1-pentene.

19. The method according to any one of claims 1 to 18, wherein: The stream comprising a concentration of 60-99 wt.% of linear and / or branched C5-C8 primary alcohols having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group is converted into at least one lower olefin having C4-C7 carbon atoms in a yield of at least about 80 wt.% of the maximum theoretical molar yield.

20. The method according to any one of claims 1 to 18, wherein: The method comprises the following steps: a) feeding a stream comprising a concentration of 60-99 wt.% of linear and / or branched C5-C8 primary alcohols having at least one hydrogen atom attached to a carbon atom adjacent to the carbon atom bearing the alcohol group into a reaction vessel, b) oxidizing the primary alcohol to the corresponding carboxylic acid, and c) oxidative decarboxylation of the carboxylic acid to an olefin having one less carbon atom than the starting alcohol, wherein a linear or branched C5-C8 primary alcohol is converted to at least one lower olefin having C4-C7 carbon atoms in a yield of at least about 80 wt.% of the maximum theoretical molar yield.

Images