Conversion of glycerol to fuel range organic compounds

Abstract

Provided herein is a method for producing fuel range organic oxygenates. The process comprises converting glycerol in the presence of a metal oxide catalyst. The fuel range organic oxygenates may be deoxygenated to produce gasoline and jet fuel or fuel blend components.

Description

Technical Field

[0001] The present disclosure relates to a process for converting glycerol to organic oxygenates having boiling points in the gasoline and jet fuel range. Background Art

[0002] As global demand for gasoline and jet fuel continues to increase, interest in feedstock sources other than petroleum crude is growing.

[0003] Glycerol (1,2,3-propanetriol) is produced in large quantities as a byproduct in the production of biodiesel. With the growing interest in using biofuels to at least partially replace petroleum fuels, the production of glycerol has increased to levels far exceeding current demand. As a result, crude glycerol is a cheap and readily available material, and there is growing interest in developing suitable applications for glycerol, especially in countries where biofuel production is prevalent.

[0004] The increasing production of biodiesel produced by transesterification of lipids with light alcohols such as methanol has resulted in the production of large amounts of glycerol in a slightly diluted form and containing varying amounts of dissolved non-volatile salts and other impurities. This form of glycerol is not suitable for use as a renewable fuel and requires expensive purification before use in most chemical applications, as it contains large amounts of water and impurities that affect the technical quality of biodiesel.

[0005] Glycerol can be hydroprocessed to form propane, which can be used as a renewable LPG fuel, but the conversion requires large amounts of hydrogen, and the technical glycerol byproduct in biodiesel production requires extensive purification before it can be hydroprocessed. LPG also has limited applications, so if glycerol could be converted into liquid transportation fuels such as gasoline, jet fuel or diesel, its value would be greater.

[0006] There is a need for a glycerol conversion process that can be used to convert crude glycerol from soap or biodiesel production into renewable transportation fuels, such as sustainable aviation fuel (SAF), or renewable chemicals. The process herein is capable of processing low-cost crude glycerol containing a large amount of impurities and water without any significant pretreatment or water removal, while converting the glycerol into a product that can be processed directly in a hydrotreater without additional pretreatment. Summary of the invention

[0007] In one aspect, a method for producing fuel range organic compounds is provided, the method comprising the steps of: (a) reacting a glycerol stream with a metal oxide catalyst at a temperature of 300° C. to 700° C. and a pressure of 100 kPa to 10 MPa to obtain a gaseous product mixture comprising one or more fuel range organic oxygenates, carbon dioxide, and one or more volatile organic compound by-products; and (b) separating the one or more fuel range organic oxygenates from the carbon dioxide and the one or more volatile organic compound by-products. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 The boiling point distribution of the fuel range organic oxygenates prepared according to Example 2 is shown. DETAILED DESCRIPTION

[0009] definition

[0010] The term "renewable" refers to a natural resource that can be replenished within a 100-year time frame. Resources can be replenished by natural means or via agricultural techniques. Renewable resources include plants, animals, fish, bacteria, fungi, and forestry products. Fossil resources, such as crude oil (petroleum), natural gas, and coal are not considered renewable resources. For clarity and for the purposes of this disclosure, the terms "renewable," "bio-based," "non-petroleum," and "non-fossil-derived" may be used interchangeably.

[0011] The term "gasoline" may include hydrocarbons having a boiling temperature in the range of about 25°C to about 200°C at atmospheric pressure.

[0012] The terms "jet fuel range hydrocarbons", "jet fuel range paraffins", "jet fuel range fuels" or "jet fuel" as used herein may include hydrocarbons having a boiling point temperature in the range of about 150° C. to 300° C., preferably 200° C. to 300° C. at atmospheric pressure. In addition, the terms "jet fuel range hydrocarbons", "jet fuel range paraffins", "jet fuel range fuels" or "jet fuel" as used herein refer to a mixture of primarily C8 to C16 hydrocarbons having a maximum freezing point of about -40° C. or about -47° C.

[0013] The term "fuel range" means hydrocarbons having carbon numbers from about C3 to about C18.

[0014] The term "ketone" refers to an organic compound having the structure RC(═O)R', wherein R and R' can be a variety of hydrocarbon substituents. The hydrocarbon substituent can be saturated or unsaturated, linear or branched, cyclic or acyclic, aromatic or non-aromatic. Ketones can also include molecules with two or more carbonyl moieties or other oxygen-containing moieties (such as hydroxyl moieties). In addition, hydrocarbon compounds having multiple ketone functional groups and mixed ketone and monohydroxyl functional groups (monohydric function) (i.e., keto-monohydroxy aliphatic alcohols) are also included, with such keto-monohydroxy alcohols. The most preferred ketones are open-chain ketones and other ketones with aliphatic groups, wherein each aliphatic group is independently a linear or branched linear aliphatic group.

[0015] The term "volatile organic compounds (VOCs)" is used to denote all organic materials that can exist in the gas phase at room temperature and atmospheric pressure, such as hydrocarbons consisting only of carbon and hydrogen, hydrocarbons containing nitrogen or oxygen, and the like.

[0016] The term "hydrodeoxygenation" refers to a catalytic process in which hydrogen is used to reduce the oxygen content of an oxygen-containing organic compound such as an ester, carboxylic acid, ketone, aldehyde, or alcohol. Complete hydrodeoxygenation of such compounds typically produces alkanes in which carbon atoms previously bonded to oxygen atoms become saturated with hydrogen (i.e., the carbon atoms have been "hydrodeoxygenated").

[0017] As used herein, the term "Cn hydrocarbon" or "Cn" has its well-known meaning, i.e., where "n" is an integer value, and refers to hydrocarbons having that number of carbon atoms. The term "Cn+ hydrocarbon" or "Cn+" refers to hydrocarbons having that number of carbon atoms or more. The term "Cn- hydrocarbon" or "Cn-" refers to hydrocarbons having that number of carbon atoms or less.

[0018] The terms "weight %", "volume %" or "mole %" refer to the weight, volume or mole percentage of a component based on the total weight, total volume or total moles of the material including the component, respectively. In a non-limiting example, 10 moles of a component in 100 moles of a material is 10 mole % of the component.

[0019] Glycerol conversion

[0020] In the conversion step, the glycerol is converted to one or more fuel range organic oxygenates by reacting the glycerol stream over a metal oxide catalyst under appropriate conditions.

[0021] Glycerol stream may be pure or impure. Crude glycerol is a natural byproduct from fat and oil processing. For example, it is produced during the transesterification of biodiesel production process. Crude glycerol may contain impurities, including water, inorganic salts (such as chlorides, sulfates, phosphates, acetates, etc.), organic compounds (such as fatty acids, fatty esters, monoglycerides, diglycerides, phospholipids, protein residues, methanol, acids, alkalis or any combination thereof). Impurities may account for 10 % by weight to 50 % by weight of crude glycerol. At least a portion of impurities can be removed from crude glycerol by various treatment processes, including neutralization, precipitation, filtration, evaporation, stripping, ion exchange, adsorption, membrane separation (such as microfiltration, nanofiltration, osmosis and reverse osmosis), electrodeionization and any combination. In some aspects, glycerol stream does not undergo any treatment steps before processing.

[0022] Fatty acid-free glycerol is generally available in several grades: pharmaceutical grade (USP), food additive grade, and technical grade (industrial grade). The dry basis composition of USP glycerol must meet 99.7% to 100% purity standards, and any trace impurities must meet USP specifications. Technical grade glycerol is usually purified (e.g., about 80% to about 97% pure), where most of its contaminants are removed (e.g., methanol, soaps, salts, etc.).

[0023] The glycerol stream can comprise at least 10 wt % (e.g., at least 20 wt %, or at least 30 wt %, or at least 40 wt %, or at least 50 wt %, or at least 60 wt %, or at least 70 wt %, or at least 80 wt %, or at least 90 wt %, or at least 95 wt %, or at least 99 wt %) glycerol.

[0024] The glycerol stream may be contacted with liquid or gaseous water (i.e., steam) such that the resulting feed stream comprises up to 30 wt% (e.g., 0.1 wt% to 30 wt% or 0.5 wt% to 20 wt%) water based on the total weight of the feed stream. If the glycerol stream is fed to the reactor in liquid form, the water is preferably fed in the form of steam, thereby sparging the steam into the glycerol stream or sparging the glycerol stream into the steam.

[0025] Any suitable catalyst can be used to convert glycerol. For example, the catalyst can be a metal oxide catalyst. Representative metal oxides include aluminum oxide, silicon dioxide-alumina, niobium oxide, titanium dioxide and zirconium oxide. The metal oxide catalyst can also include a modifier to enhance selectivity and / or activity. Suitable modifiers include La, Y, Sc, Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba and any combination thereof. Based on the gross weight of the catalyst composition, the amount of the modifier can be in the range of 0.1 wt % to 20 wt % (e.g., 0.25 wt % to 10 wt % or 0.5 wt % to 5 wt %).

[0026] Metal oxide catalysts can have 10m 2 / g to 400m 2 / g (e.g., 20m 2 / g to 200m 2 / g or 50m 2 / g to 200m 2 / g) in the range of surface area.

[0027] The catalyst may be in any common catalyst shape known in the art, such as, for example, spheres, granules, pellets, chips, rings, extrudates or powders.

[0028] The catalyst can be regenerated by heating in the presence of an oxygen-containing gas at a temperature of 375° C. to 550° C. Steam can be introduced simultaneously during regeneration.

[0029] The reactor can be any reactor form suitable for gas phase endothermic reaction known in the art. For example, the reactor can be carried out using a fixed bed reactor, a fluidized bed reactor or a moving bed reactor. In some aspects, the glycerol conversion can be carried out in a single-stage adiabatic fixed bed reactor, a multi-stage adiabatic reactor or a tubular fixed bed reactor. Since the glycerol conversion is endothermic, the reactor can be operated in an adiabatic manner.

[0030] The reactor may be operated at a temperature of 300°C to 700°C (eg, 350°C to 600°C).

[0031] The pressure may be in the range of 100 kPa to 10 MPa (eg, 100 kPa to 5 MPa).

[0032] In the reactor, glycerol is converted into a gaseous product mixture comprising fuel range organic oxygenates, carbon dioxide and one or more volatile organic compounds. The fuel range organic oxygenates can be separated from carbon dioxide and VOC by conventional methods known in the art. For example, the gaseous product mixture from the reactor can be separated by direct condensation to produce a liquid stream comprising a crude fuel range organic oxygenate and a gaseous byproduct stream carbon comprising carbon dioxide and volatile organic compounds. In one aspect, the separation step comprises cooling the gaseous product mixture by contacting with a heat exchanger or a solvent. For example, the fuel range organic oxygenates can be indirectly cooled by water, frozen brine, frozen ethylene glycol, etc. in a heat exchanger, or condensed via direct contact cooling with the injected solvent (such as water). After cooling, phase separation produces a byproduct carbon dioxide stream mainly comprising non-condensable components (carbon dioxide and volatile organic compounds) and a liquid stream comprising a crude fuel range organic oxygenate.

[0033] According to the inventive method, many oxygens in the glycerine are discharged with CO2 form, and the residual oxygen found in the product mainly exists in the form of C3-C12 ketone and a small amount of C6-12 phenol derivative. In some respects, the fuel range organic oxygen-containing compound comprises at least 50 % by weight (for example, at least 60 % by weight or at least 70 % by weight or at least 80 % by weight or at least 90 % by weight or at least 95 % by weight) of C3-12 ketone. In some respects, the fuel range organic oxygen-containing compound comprises and is less than 40 % by weight (for example, is less than 30 % by weight, is less than 20 % by weight or is less than 10 % by weight or is less than 5 % by weight) of C6-C12 phenol.

[0034] Following condensation and separation of the carbon dioxide by-product, the liquid stream comprising crude fuel-range organic oxygenates may be distilled to produce one or more fractions boiling in the gasoline or jet fuel range.

[0035] After condensation and separation of the carbon dioxide byproduct, the liquid stream containing the crude fuel range organic oxygenates can be fractionated (e.g., by distillation) into different fractions, each of which is known to be within a certain boiling point range. For example, fractionation can be performed at a determined fractionation temperature or boiling point cutoff to separate the various boiling point fractions suitable for the desired fuel product and collect light products for further processing. The distillate fractions can be any or all of naphtha, jet fuel, diesel or other fuel ranges. These fractions can be hydrotreated to obtain paraffin and isoparaffin fuels or fuel mixture feedstocks.

[0036] In some aspects, fractionation can be performed after all other post-processing (e.g., hydroprocessing) has been completed in order to more accurately control the composition of the collected fractions. For example, such control may be desirable if a specific boiling point range is required to meet the specifications of a desired fuel type.

[0037] Hydroprocessing

[0038] The fuel range organic oxygenates obtained from the glycerol conversion step may be subjected to a catalytic hydroprocessing step to provide hydrocarbons suitable for use as renewable fuels or fuel components, useful as transportation fuels, fuel components and other chemicals.

[0039] Catalytic hydroprocessing includes at least a hydrodeoxygenation (HDO) step.

[0040] The hydrodeoxygenation reaction can be carried out in the presence of hydrogen and a hydrodeoxygenation catalyst such as CoMo, NiMo, NiW, CoNiMo on a support (alumina, silica, alumina-silica, zirconia). The hydrodeoxygenation step can be carried out using a catalyst such as NiMo, optionally on an alumina support, at a temperature of 100° C. to 500° C. (e.g., 250° C. to 400° C.) and a pressure of 2 MPa to 15 MPa (e.g., 4 MPa to 10 MPa), 0.1 h -1 Until 10h -1 (For example, 0.2h -1 Until 5h -1 ) and a hydrogen flow rate of 350 to 900 NL H2 / L feed.

[0041] Water and light gases can be separated from the HDO product using any conventional means such as distillation. After removing water and light gases, the HDO product can be fractionated into one or more fractions suitable for use as gasoline, aviation fuel, diesel or heavy oil components. Fractionation can be performed by any suitable means, such as distillation. Optionally, a portion of the product of the HDO step can be recovered and incorporated into the feed to the HDO reactor.

[0042] Catalytic hydroprocessing can also include an isomerization step in the presence of hydrogen and an isomerization catalyst. The HDO step and the isomerization step can be carried out in the same reactor. In some aspects, the isomerization catalyst is a noble metal bifunctional catalyst (e.g., Pt-SAPO-11, Pt-ZSM-48). The isomerization step can be carried out at a temperature of 200° C. to 400° C. and a pressure of 2Mpa to 15MPa. Fractionation can be carried out before or after isomerization, but is preferably carried out after isomerization. Preferably, the isomerization step is not carried out.

[0043] Example

[0044] The following illustrative examples are intended to be non-limiting.

[0045] Example 1

[0046] Catalyst preparation

[0047] Alumina was wetted to incipient wetness with a calcium acetate solution of 10 g (CH3CO2)2Ca dissolved in 50 mL water, dried in air at 120°C-150°C, and calcined at 900°F to obtain a calcium-promoted alumina catalyst.

[0048] Example 2

[0049] The fixed bed reactor was filled with 50 cm 3The calcium-promoted alumina catalyst of Example 1 was used. Glycerin and steam were each fed to the reactor at a rate of 1 g / min. The reactor was operated at 900°F and atmospheric pressure. The reactor effluent was cooled to ambient temperature, producing an oil phase, an aqueous phase, and a gas stream.

[0050] The effluent was analyzed by gas chromatography-mass spectrometry (GC-MS).

[0051] The oil yield is 15-25 wt% relative to the converted glycerol. Figure 1 The GC-boiling point curve of the recovered oil product is shown. The oil contains about 50% ketones and aldehydes, about 30% phenol derivatives (eg, alkylphenols, polyalkylphenols, phenol ethers) and about 20% hydrocarbons.

[0052] An additional 10-15 wt% (relative to the oil phase) of most of the light carbonyls (e.g., acetaldehyde, acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isopropyl ketone) are extracted from the aqueous phase (<5 wt% relative to the converted glycerol). When the organics extractable from the aqueous phase are combined with the oil phase contents, the light C3-C5 ketones (e.g., acetone, methyl ethyl ketone, pentanone) account for about one quarter of the total recovered liquid product by weight.

[0053] The gas stream contains light hydrocarbons (C1-C4) in an amount corresponding to a yield of about 5% to 10% by weight relative to the glycerol converted, and CO2 in an amount corresponding to a yield of about 30% to 35% by weight relative to the glycerol converted.

[0054] The product mixture is surprisingly rich in compounds boiling in the range of naphtha and jet fuel boiling points, and has a significantly lower oxygen content than the glycerol feedstock. Surprisingly, much of the oxygen in the glycerol is expelled as CO2, while the residual oxygen found in the product is primarily in the form of ketones (cyclic and acyclic, saturated and unsaturated, 3 to 12 carbons per molecule), and to a lesser extent in the form of phenol derivatives (6-12 carbons per molecule).

[0055] The higher CO2 production is unexpected and valuable. The advantage is that the organic product produced has a higher hydrogen / carbon ratio than the organic product obtained by simple glycerol dehydration. The method can discharge the oxygen in glycerol mainly in the form of CO2 rather than water, which determines that it can produce products rich in high-value components such as C3-C5 ketones. In addition, if the glycerol conversion is intended to produce fuel products, discharging oxygen in the form of CO2 will greatly reduce the demand for hydrogen and the exothermic heat of reaction in subsequent hydroprocessing.

Claims

1. A method for producing distillate range organic compounds, the method comprising the steps of: (a) reacting a glycerol stream with a metal oxide catalyst at a temperature of 300° C. to 700° C. and a pressure of 100 kPa to 10 MPa to obtain a gaseous product mixture comprising one or more fuel range organic oxygenates, carbon dioxide, and one or more volatile organic compound by-products; and (b) separating the one or more fuel range organic oxygenates from the carbon dioxide and one or more volatile organic compound by-products.

2. The process of claim 1, wherein the glycerol stream does not undergo a treatment step.

3. The method of claim 2, wherein the treatment step is selected from the group consisting of neutralization, precipitation, filtration, evaporation, stripping, ion exchange, adsorption, membrane separation, and any combination thereof.

4. The method of claim 1, wherein the metal oxide catalyst comprises alumina, silica-alumina, niobium oxide, titanium oxide, zirconium oxide, or any combination thereof.

5. The method of claim 1, wherein the metal oxide catalyst further comprises 0.1 wt % to 20 wt % of a modifier based on the total weight of the catalyst, the modifier being selected from the group consisting of La, Y, Sc, Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, and any combination thereof.

6. The method of claim 1, wherein step (a) is carried out in the presence of water and / or steam.

7. The process of claim 1, wherein step (a) is carried out in a fixed bed reactor.

8. The process of claim 1, wherein step (b) comprises cooling the gaseous product mixture by contact with a heat exchanger or a solvent.

9. The method of claim 1 further comprising hydrodeoxygenating the one or more fuel range organic oxygenates to form a deoxygenated product comprising hydrocarbons.

10. The method of claim 9, wherein the hydrodeoxygenation is carried out in the presence of a hydrodeoxygenation catalyst at a temperature of 100°C to 500°C; a pressure of 2 MPa to 15 MPa; 0.1 h -1 Until 10h -1 and a hydrogen flow of 350 to 900 NL H2 / L feed.

11. The method of claim 9, further comprising distilling the deoxygenated product stream to obtain one or more of gasoline and jet fuel.

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