US20080066374A1

US20080066374A1 - Reaction system for production of diesel fuel from vegetable and animals oils

Info

Publication number: US20080066374A1
Application number: US11/892,797
Authority: US
Inventors: Mordechay Herskowitz
Original assignee: Ben Gurion University of the Negev Research and Development Authority Ltd
Current assignee: Ben Gurion University of the Negev Research and Development Authority Ltd
Priority date: 2006-09-19
Filing date: 2007-08-27
Publication date: 2008-03-20
Also published as: WO2008035155A2; WO2008035155A3

Abstract

A process for producing a fuel composition from vegetable and/or animal oil comprises feeding the oil to a tubular reaction unit containing a catalyst comprising an acidic component and a metal component, feeding effluent from the tubular reaction unit to a vapor-liquid separator, and feeding a vapor phase separated from the effluent from the tubular reaction unit to an adiabatic reaction unit comprising the same catalyst as in the tubular reaction unit comprising an acidic component and a metal component. The produced fuel composition has acceptable lubricity and comprises a mixture of C₁₂to C₁₈or C₁₄to C₁₈paraffins having a ratio of iso to normal paraffins of 2 to 8 and less than 5 ppm sulfur.

Description

BACKGROUND

1. Field of Art
Provided is a process and reaction system for the production of liquid fuels, particularly diesel, jet and naphtha fuels, from vegetable and/or animal oils.
2. Description of the Related Art
Most combustible liquid fuels used for on road, off road, stationary engines, and combustion turbines and boilers in the world today are derived from crude oil. However, there are several limitations to using crude oil as a fuel source. For example, crude oil is in limited supply, includes a high content of aromatics, and contains sulfur and nitrogen-containing compounds that can adversely affect the environment. There is a great desire and need in the industry to provide combustible liquid fuels that are more environmentally friendly, display good engine performance, and which are available from alternative sources that are abundantly renewable.
Vegetable and animal oils are an abundant and renewable source. The use of vegetable oil in diesel engines requires significant engine modification, including changing of piping and injector construction materials, otherwise engine running times are decreased, maintenance costs are increased due to higher wear, and the danger of engine failure is increased. The current conversion of vegetable and animal oils to combustible liquid fuels typically involves transesterification of the oils, which are triglycerides of C₁₄to C₂₂straight-chain carboxylic acids, with a lower alcohol such as methanol or ethanol, to form a mixture of methyl or ethyl esters called “biodiesel”. This process is relatively complex, typical of the chemical industry rather than the petrochemical industry. Furthermore, the composition of biodiesel, which is completely different from that of diesel produced from crude oil, may have adverse effects on engine performance. Biodiesel exhibits poor low temperature performance characteristics and increased nitrogen oxide (NO_x) emissions compared to conventional fuels derived from crude oil.
In the search for alternative and renewable sources, there is increasing interest in producing liquid fuels from biological raw materials for use as fuel by themselves or in mixture with the petroleum-derived fuels in use today. The patent literature describes methods for producing hydrocarbon mixtures from biological sources, including vegetable oils.
United Kingdom Patent Specification 1 524 781 discloses converting ester-containing vegetable oils into one or more hydrocarbons by pyrolysis at 300 to 700° C. in the presence of a catalyst which comprises silica-alumina in admixture with an oxide of a transition metal of Groups IIA, IIIA, IVA, VA, VIA, VIIA or VIII of the periodic table, preferably in a fluidized bed, moving bed or fixed bed tubular reactor at atmospheric pressure.
U.S. Pat. No. 5,705,722 discloses a process for producing additives for diesel fuels having high cetane numbers and serving as fuel ignition improvers. In the process, biomass feedstock selected from (a) tall oil containing less than 0.5 wt % ash, less than 25 wt % unsaponifiables, up to 50 wt % diterpenic acids and 30 to 60 wt % unsaturated fatty acids, (b) wood oils from the pulping of hardwood species, (c) animal fats and (d) blends of said tall oil with plant or vegetable oil containing substantial amounts of unsaturated fatty acids or animal fats, is subjected to hydroprocessing by contacting the feedstock with gaseous hydrogen under hydroprocessing conditions in the presence of a hydroprocessing catalyst to obtain a product mixture. This product mixture is then separated and fractionated to obtain a hydrocarbon product boiling in the diesel fuel boiling range, this product being the high cetane number additive.
U.S. Patent Publication No. 2004/0055209 discloses a fuel composition for diesel engines comprising 0.1-99% by weight of a component or a mixture of components produced from biological raw material originating from plants and/or animals and/or fish and 0-20% of components containing oxygen. Both components are mixed with diesel components based on crude oil and/or fractions from Fischer-Tropsch process.
U.S. Patent Publication No. 2004/0230085 discloses a process for producing a hydrocarbon component of biological origin comprising at least two steps, the first one of which is a hydrodeoxygenation step and the second one is an isomerization step operated using the counter-current flow principle. A biological raw material containing fatty acids and/or fatty acid esters serves as the feed stock.
Fuel properties important for potential diesel applications include: (i) lubricity; (ii) cetane number; (iii) density; (iv) viscosity; (v) lower heating value; (vi) sulfur; (vii) flash point; (viii) cloud point; (ix) Distillation Curve; (x) carbon residue; (xi) ash; and (xii) Iodine Value. Lubricity affects the wear of pumps and injection systems. Lubricity can be defined as the property of a lubricant that causes a difference in friction under conditions of boundary lubrication when all known factors except the lubricant itself are the same; thus, the lower the friction, the higher the lubricity. Cetane number rates the ignition quality of diesel fuels. Density, normally expressed as specific gravity, is defined as the ratio of the mass of a volume of the fuel to the mass of the same volume of water. Viscosity measures the fluid resistance to flow. Lower heating value is a measure of available energy in the fuel. Flash point is the lowest temperature at which a combustible mixture can be formed above the liquid fuel. Cloud point measures the first appearance of wax. Distillation Curve is characterized by the initial temperature at which the first drop of liquid leaves the condenser and subsequent temperatures at each 10 vol % of the liquid. Carbon residue correlates with the amount of carbonaceous deposits in a combustion chamber. Ash refers to extraneous solids that reside after combustion. Iodine Value measures the number of double bonds.
A comparison of properties of biodiesel and EN standard EN590:2005 diesel can be found in Table 1.

TABLE 1

		EN590
Fuel Property	Biodiesel	Diesel

Density @ 15° C., kg/m³	≈885	≈835
Viscosity @ 40° C., mm²/s	≈4.5	≈3.5
Cetane Number	≈51	≈53
90 vol % Distillation, ° C.	≈355	≈350
Cloud Point, ° C.	≈−5	≈−5
Lower Heating Value, MJ/kg	≈38	≈43
Lower Heating Value,	≈34	≈36
MJ/liters
Polyaromatics, wt %	0	≈4
Oxygen, wt %	≈11	0
Sulfur, mg/kg	<10	<10

The American Society for Testing and Materials (ASTM) standards for commercial diesel (ASTM D975) and biodiesel (ASTM D6751) can be found in Table 2.

TABLE 2

	Diesel	Biodiesel
Fuel Property	ASTM D975	ASTM D6751

Lower Heating Value, BTU/gal	129,050	118,170
Kinematic Viscosity @ 40° C.,	1.3-4.1	4.0-6.0
cSt
Specific Gravity @ 60° C.,	0.85	0.88
g/cm³
Carbon, wt %	87	77
Hydrogen, wt %	13	12
Oxygen, by dif. wt %	0	11
Sulfur, ppm	500	0
Boiling Point, ° C.	180 to 340	315 to 350
Flash Point, ° C.	60 to 80	100 to 170
Cloud Point, ° C.	−15 to 5	−3 to 12
Pour Point, ° C.	−35 to −15	−5 to 10
Cetane Number	40-55	48-65
Lubricity (HFRR), μm	300-600	<300

There remains a need for alternative processes for conversion of vegetable and animal oils to fuels and diesel fuel compositions derived from vegetable and animal oils having better and more acceptable properties.

SUMMARY

Provided is a process for producing a liquid fuel composition comprising providing oil selected from the group consisting of vegetable oil, animal oil, and mixtures thereof and hydrodeoxygenating and hydroisomerizing the oil. The hydrodeoxygenating and hydroisomerizing comprises feeding the oil to a tubular reaction unit containing a catalyst comprising an acidic component and a metal component, feeding effluent from the tubular reaction unit to a vapor-liquid separator, and feeding a vapor phase separated from the effluent from the tubular reaction unit to an adiabatic reaction unit comprising the same catalyst as in the tubular reaction unit comprising an acidic component and a metal component. Liquid separated from the effluent from the tubular reaction unit can be recycled to the tubular reaction unit. In an embodiment, the tubular reaction unit is a multi-tubular reaction unit and/or operates in trickle-bed mode and the adiabatic reaction unit comprises a single tube.
Additionally provided is a reaction system for producing a liquid fuel composition comprising a tubular reaction unit containing a catalyst comprising an acidic component and a metal component, an adiabatic reaction unit containing the same catalyst as in the tubular reaction unit comprising an acidic component and a metal component, and a vapor-liquid separator disposed between the tubular reaction unit and the adiabatic reaction unit. The adiabatic reaction unit can be located downstream of the tubular reaction unit. In an embodiment, the tubular reaction unit is a multi-tubular reaction unit and/or operates in trickle-bed mode and the adiabatic reaction unit comprises a single tube.

DETAILED DESCRIPTION

High quality liquid fuels, in particular diesel and naphtha fuels, can be obtained from vegetable and/or animal oils in high yield by a process comprising hydrodeoxygenation and hydroisomerization. Triglycerides of fatty acids contained in the vegetable and/or animal oil are deoxygenated to form normal C₁₂to C₁₈or C₁₄to C₁₈paraffins, which are hydroisomerized in the same stage to form various isoparaffins. Minor cyclization and aromatization to alkyl cyclohexane and alkyl benzene may also occur. The deoxygenation can comprise removal of oxygen in the form of water and carbon oxides from the triglycerides. Hydrocracking is inhibited, so as to maintain the range of carbon number of hydrocarbons formed in the range of C₁₂to C₁₈or C₁₄to C₁₈.
Hydrodeoxygenation of vegetable and/or animal oils alone would generate a mixture of long-chain straight C₁₂to C₁₈or C₁₄to C₁₈paraffins. While such long-chain straight C₁₂to C₁₈or C₁₄to C₁₈paraffins would be in the paraffin carbon number range of diesel fuels, the fuel properties of such long-chain straight C₁₂to C₁₈or C₁₄to C₁₈paraffins would be significantly different from those of diesel fuels. Therefore, production of diesel fuel requires hydroisomerization of the paraffins. Accordingly, the presently disclosed process for producing a liquid fuel composition comprises providing oil selected from the group consisting of vegetable oil, animal oil, and mixtures thereof and hydrodeoxygenating and hydroisomerizing the oil. In addition to hydrocarbon products within the diesel boiling range, the liquid fuel composition produced by the presently disclosed process may further comprise 2-10% lighter naphtha products boiling below 150° C. as well as heavier distillate products.
The hydrodeoxygenating and hydroisomerizing disclosed herein comprises feeding the oil to a tubular reaction unit containing a catalyst comprising an acidic component and a metal component, feeding effluent from the tubular reaction unit to a vapor-liquid separator, and feeding a vapor phase separated from the effluent from the tubular reaction unit to an adiabatic reaction unit comprising the same catalyst as in the tubular reaction unit comprising an acidic component and a metal component. While the effluent from the tubular reaction unit is primarily in a vapor phase, liquid separated from the effluent from the tubular reaction unit can be recycled to the tubular reaction unit. In an embodiment, the tubular reaction unit, which is contained within a shell, is a multi-tubular reaction unit and/or operates in trickle-bed mode and the adiabatic reaction unit comprises a single tube.
As exothermic hydrodeoxygenation and double-bond saturation reactions take place in the tubular reaction unit, a significant amount of heat of reaction is removed from the tube(s) (e.g., 1,000 or even 5,000 tubes) of the tubular reaction unit, for example, by coolant contained in a shell jacketing the tube(s) for optimal temperature control. The vapor-liquid separator disposed downstream of the tubular reaction unit functions as a heat exchanger and sets the temperature of the vapor phase exiting the vapor-liquid separator, which is to be fed to the reaction unit following the vapor-liquid separator. In an embodiment, the vapor phase leaves the vapor-liquid separator at a temperature of about 330 to 400° C. As mild, vapor-phase hydroisomerization and similar reactions take place in the reaction unit following vapor-liquid separation, the reaction unit is adiabatic, and thus, in addition to setting the temperature of the vapor phase exiting the vapor-liquid separator, the vapor-liquid separator also sets the temperature of the reaction unit following the vapor-liquid separator and allows for optimization of the process. Use of both tubular and adiabatic reaction units allows for optimization of the hydrodeoxygenating and hydroisomerizing and improved performance and stability of the catalyst. The tubular reaction unit, vapor-liquid separator, and adiabatic reaction unit may be contained within one or more reaction vessels.
In an embodiment, catalysts for the presently disclosed process are dual-functional catalysts comprising a metal component and an acidic component. In an embodiment, metal components are platinum or palladium. In an embodiment, the metal component is platinum. The acidic component can comprise an acidic function in a porous solid support. In an embodiment, acidic components include, for example, amorphous silica aluminas, fluorided alumina, ZSM-12, ZSM-21, ZSM-22, ZSM-23, ZSM-35, ZSM-38, ZSM-48, ZSM-57, SSZ-32, ferrierite, SAPO-11, SAPO-31, SAPO-41, MAPO-11, MAPO-31, Y zeolite, L zeolite and Beta zeolite. In an embodiment, the catalyst is Pt/SAPO-11, specifically 0.5-1 wt % Pt/SAPO-11, more specifically 1 wt % Pt/SAPO-11.
The type and content of metal, acid strength, type and concentration of acid sites, solid porosity and pore size affect the type and quality of the diesel fuel produced. U.S. Pat. Nos. 5,082,986, 5,135,638, 5,246,566, 5,282,958, and 5,723,716, the entire contents of which are hereby incorporated by reference, disclose representative process conditions using said catalysts for isomerization of different hydrocarbon feedstock. Further, typical processes and catalysts for dewaxing and hydroisomerization are described, for example, in U.S. Pat. No. 6,702,937, the entire content of which is hereby incorporated by reference, and the references cited therein.
The process is carried out at relatively mild conditions, for example, the tubular reaction unit is operated at conditions comprising a liquid hourly space velocity (LHSV) in the range of 0.5-5 h⁻¹, for example, 0.6-3 h⁻¹, 0.7-1.2 h⁻¹, or 1-2.5 h⁻¹, at a temperature varying between 300 and 450° C., for example, between 320 and 400° C., at a pressure varying between 10 and 60 atm, for example, 20-40 atm, and a H₂/oil ratio of about 300-1200 NL/L, for example, 500-1000 NL/L. More severe conditions result in liquid fuel compositions with poorer lubricity, while more moderate to mild conditions result in liquid fuel compositions with better lubricity.
Lubricity is especially important with regard to modern diesel fuels, as modern engines have very high injection pressures in excess of 24,000 pounds per square inch. Good lubricity is necessary to prevent risk of catastrophic engine failure. In general, an acceptable lubricity refers to a lubricity that would allow modern engines to operate more efficiently. In an embodiment, the diesel fuel has a maximum high-frequency reciprocating rig (HRFF) lubricity of 400 μm (according to International Organization for Standardization (ISO) standard 12156/1), in accordance with the recommendation of the World Wide Fuel Charter, Category 4. In an embodiment, the lubricity is less than 300 μm according to ISO 12156/1, for example, the lubricity is less than 200 μm according to ISO 12156/1.
Any vegetable and/or animal oil can be used in the presently disclosed process. For example, suitable vegetable oils include soybean oil, palm oil, corn oil, sunflower oil, oils from desertic plants such as, for example, jatropha oil and balanites oil, rapeseed oil, colza oil, canola oil, tall oil, safflower oil, hempseed oil, olive oil, linseed oil, mustard oil, peanut oil, castor oil, coconut oil, and mixtures thereof. In an embodiment, vegetable oils include soybean oil, palm oil, corn oil, sunflower oil, jatropha oil, balanites oil, for example, from Balanites aegyptiaca, and mixtures thereof. The vegetable oil may be genetically modified oil, produced from transgenic crops. The vegetable oil may be crude vegetable oil or refined or edible vegetable oil. If crude vegetable oil is used, the vegetable oil can be pretreated, for example, to separate or extract impurities from the crude vegetable oil. Suitable animal oils include, for example, lard oil, tallow oil, train oil, fish oil, and mixtures thereof. Further, the vegetable and/or animal oil may be new oil, used oil, waste oil, or mixtures thereof.
The oil, or mixture of oils, used in the presently disclosed process can contain a high content of fatty acids (e.g., greater than or equal to 70 wt % fatty acids). Additionally, compositions derived from vegetable and/or animal oil that contains a high content of fatty acids can be used in the presently disclosed process. The phrase “compositions derived from vegetable and/or animal oil” refers to compositions which originate from or are the byproduct of processing vegetable and/or animal oil (e.g., vapor overhead stream from distilling vegetable and/or animal oil, residual non-vaporizable remaining portion, etc.). Thus, palm oil distillate containing greater than 70 wt % fatty acids can be used in the presently disclosed process.
The diesel fuel composition produced by the presently disclosed methods comprises a mixture of C₁₂to C₁₈or C₁₄to C₁₈paraffins with a ratio of iso to normal paraffins from 0.5 to 8, for example, from 2 to 8, from 2 to 6, from 2 to 4, from 1 to 4, or from 4 to 7; less than 5 ppm sulfur, for example, less than 1 ppm sulfur; and acceptable lubricity. Specifically, the diesel fuel composition can have a lubricity of less than 400 μm, for example, less than 300 μm or less than 200 μm, according to ISO 12156/1.
Additionally, the diesel fuel composition can comprise less than or equal to 0.6 wt %, for example, 0.1-0.6 wt %, of one or more oxygenated compounds, which, without wishing to be bound by any theory, are believed to contribute to the acceptable lubricity of the diesel fuel composition. In an embodiment, the one or more oxygenated compounds comprise acid, for example, one or more fatty acids. In an embodiment, the one or more oxygenated compounds (e.g., acid), is present in an amount of less than or equal to 0.4 wt %, for example, 0.1-0.4 wt %. As used herein, the phrase “fatty acids” refers to long chain saturated and/or unsaturated organic acids having at least 8 carbon atoms, for example, 12 to 18 or 14 to 18 carbon atoms. Without wishing to be bound by any theory, it is believed that the low content of one or more oxygenated compounds, for example, one or more fatty acids, in the diesel fuel composition may contribute to the acceptable lubricity of a diesel fuel composition; such oxygenated compounds, present in the vegetable and/or animal oil feedstock, may survive the non-severe hydrodeoxygenation/hydroisomerization conditions employed in the presently disclosed process. The diesel fuel composition may comprise alkyl cyclohexane, for example, less than 10 wt %, and/or alkyl benzene, for example, less than 15 wt %.
The characteristics of the diesel fuel composition, and naphtha, produced by the presently disclosed methods may vary depending on the vegetable and/or animal oil starting product, process conditions, and catalyst used. In an embodiment, selection of vegetable and/or animal oil starting product, process conditions, and catalyst allows for high yield of high quality diesel fuel composition, with preferred properties, and minimized production of lighter components including, for example, naphtha, carbon oxides and C₁to C₄hydrocarbons. The paraffinic diesel fuel compositions produced by the presently disclosed methods provide superior fuel properties, especially for low temperature performance (e.g., density, viscosity, cetane number, lower heating value, cloud point, and CFPP), to biodiesel, a mixture of methyl or ethyl esters. In contrast to the products of the process disclosed in U.S. Patent Publication No. 2004/0230085, disclosed herein are method for producing diesel fuel compositions with acceptable lubricities produced from vegetable and/or animal oil. More specifically, fuel properties, such as, for example, lubricity, may be controlled through variation of process conditions and/or catalyst(s). In general, with regards to the distillation curve of the diesel fuel composition produced by the presently disclosed methods, the initial boiling point (IBP) is in the range of 160° C.-240° C. and the 90 vol % distillation temperature is in the range of 300° C.-360° C. The produced naphtha is highly pure and particularly suitable for use as a solvent and/or chemical feedstock, e.g., a cracking stock.

EXAMPLES

The following examples are intended to be non-limiting and merely illustrative.

Comparative Example 1

Production of Diesel from Soybean Oil Based on U.S. Patent Publication No. 2004/0230085

Refined soybean oil was fed to a fixed-bed reactor packed with a granulated Ni—Mo catalyst operated at an LHSV of 1.0 h⁻¹, 375° C., 40 atm, and an H₂/oil ratio of 1200 NL/L (Stage 1). The total liquid product was separated into two phases, water and an organic phase. The organic phase was fed to a fixed-bed reactor packed with a granulated 1 wt % Pt/SAPO-11 catalyst operated at an LHSV of 3.0 h⁻¹, 380° C., 50 atm, and an H₂/oil ratio of 500 NL/L (Stage 2). The organic phase from Stage 1 and the diesel product from Stage 2 were analyzed according to ASTM methods and their compositions were measured by GC-MS and confirmed by NMR. The results can be found in Table 3.

	TABLE 3

	Comparative	Comparative
	Example 1	Example 1
	Stage 1	Stage 2

Oil	Soybean	Soybean
Temperature	375° C.	380° C.
Catalyst	Granulated	Granulated
	Ni—Mo	1 wt % Pt/
		SAPO-11
LHSV, hr⁻¹	1.0	3.0
Pressure, atm	40	50
H₂/oil ratio, NL/L	1200	500
Distillation Temperature
ASTM D86
IBP	194.1° C.	150° C.
10%	292.8° C.	191.1° C.
50%	303.6° C.	295.4° C.
90%	369.0° C.	356.0° C.
Up to 250° C.	2.0%	18.1%
Up to 350° C.	86.5%	89.4%
Cold Filter Plugging Point (CFPP)	17° C.	<−20° C.
IP 309
Lubricity (HFRR)	352 μm	502 μm
ISO 12156/1
Cloud Point	17° C.	<−20° C.
ASTM D2500
Kinematic Viscosity @ 40° C.	5.25 cSt	2.97 cSt
ASTM D445
Specific Gravity @ 15° C.	0.806 g/cm³	0.788 g/cm³
ASTM D1298
Composition, wt %
Linear paraffins	51.0	14.0
Branched paraffins	28.0	76.8
Alkyl cyclohexane	9.2	5.5
Alkyl benzene	2.2	0.6
Olefins	2.7	0.3
Acids	0.2	Not Detected*
Others	6.7	2.8
Degree of saturation	0.6	0.8
ASTM D1959-97

*Detection limit of 0.1 wt %

The diesel product from Stage 2 exhibited a poorer lubricity (502 μm) as compared to that of the organic phase from Stage 1 (352 μm). Without wishing to be bound by any theory, it is believed that the increase in ratio of branched to linear paraffins in the diesel product from Stage 2, as compared to the organic phase from Stage 1, resulted in a change of fuel properties.

Comparative Example 2

Production of Diesel from Soybean Oil by a Two Stage Process

Refined soybean oil was fed to a fixed-bed reactor packed with a granulated 1 wt % Pt/SAPO-11 catalyst operated at an LHSV of 1.0 h⁻¹, 380° C., 20 atm, and an H₂/oil ratio of 1200 NL/L (Stage 1). The total liquid product was separated into two phases, water and diesel product. The diesel product from Stage 1 was fed to a fixed-bed reactor packed with a granulated 1 wt % Pt/SAPO-11 catalyst operated at an LHSV of 4.5 h⁻¹, 360° C., 30 atm, and an H₂/oil ratio of 1200 NL/L (Stage 2). The diesel product from Stage 1 and the diesel product from Stage 2 were analyzed according to ASTM methods and their compositions were measured by GC-MS and confirmed by NMR. The results can be found in Table 4.

	TABLE 4

	Comparative	Comparative
	Example 2	Example 2
	Stage 1	Stage 2

Oil	Soybean	Soybean
Temperature	380° C.	360° C.
Catalyst	Granulated	Granulated
	1 wt % Pt/	1 wt % Pt/
	SAPO-11	SAPO-11
LHSV, hr⁻¹	1.0	4.5
Pressure, atm	20	30
H₂/oil ratio, NL/L	1200	1200
Distillation Temperature
ASTM D86
IBP	181.3° C.	189.7° C.
10%	263.9° C.	263.5° C.
50%	292.5° C.	292.6° C.
90%	360.3° C.	353.7° C.
Up to 250° C.	5.6%	5.4%
Up to 350° C.	88.9%	89.7%
Cold Filter Plugging Point (CFPP)	−14° C.	−17° C.
IP 309
Lubricity (HFRR)	306 μm	437 μm
ISO 12156/1
Cloud Point	−12° C.	−14° C.
ASTM D2500
Kinematic Viscosity @ 40° C.	3.82 cSt	3.60 cSt
ASTM D445
Specific Gravity @ 15° C.	0.789 g/cm³	0.794 g/cm³
ASTM D1298
Composition, wt %
Linear paraffins	26.8	23.6
Branched paraffins	52.3	58.4
Alkyl cyclohexane	4.9	8.1
Alkyl benzene	7.7	2.9
Olefins	2.9	2.9
Acids	0.4	Not Detected*
Others	5.0	4.1
Degree of saturation	0.4	0.5
ASTM D1959-97

*Detection limit of 0.1 wt %

The diesel product from Stage 1 exhibited acceptable properties, including a lubricity of 306 μm. As the composition of the diesel product from Stage 2 did not significantly differ from the diesel product from Stage 1, the properties of the diesel product from Stage 2 are similar to those of the diesel product from Stage 1. However, the diesel product from Stage 2 exhibited a poorer lubricity (437 μm) as compared to that of the diesel product from Stage 1 (306 μm), similar to the diesel production from Stage 2 of Comparative Example 1. Without wishing to be bound by any theory, it is believed that water may act as an inhibitor to isomerization, which requires higher catalyst activity, and the removal of water between Stage 1 and Stage 2 in Comparative Example 1 and Comparative Example 2 may also remove acid, thereby affecting final product lubricity.
Adding 0.1 wt % of oleic acid to the diesel product of Stage 2 improved its lubricity from 437 μm to 270 μm. Thus, as noted above, without wishing to be bound by any theory, it is believed that the low content of one or more oxygenated compounds, such as one or more fatty acids, in the product of the process may contribute to the acceptable lubricity of the diesel product.

Example 3

Production of Diesel from Soybean Oil in a Two Unit Process

The reactor setup and the operating conditions of Example 3 were based on the results of kinetic studies and reactor simulations using soybean oil. In the kinetic studies, concentrations of the soybean oil, acids, paraffins, olefins, cyclohexanes, aromatics and light compounds were measured as a function of residence time and temperature. Vapor-liquid equilibrium was provided by the reactor simulations. For a residence time of 15 to 25 minutes, the soybean oil was nearly completely converted. The acid content in the product(s) peaked at about 10 to 15 minutes, and then decreased with additional residence time. Again, diesel fuel compositions produced in accordance with the presently claimed methods can comprise less than or equal to 0.6 wt % of one or more oxygenated compounds (e.g., acids). In part due to the operating pressure, conversion of the soybean oil (e.g., for a residence time of 15 to 25 minutes) resulted in vapor phase products with only very small amounts of liquid products, which contain heavy compounds (e.g., C₂₀₊ hydrocarbons).
Accordingly, refined soybean oil was fed to a single (electrically heated) wall-cooled reactor tube, packed with a granulated 1 wt % Pt/SAPO-11 catalyst, and operated in trickle-bed mode at an LHSV of 3.5 h⁻¹, 382° C., 30 atm, and an H₂/oil ratio of 550 NL/L. The effluent of the single wall-cooled reactor tube flowed through a gas-liquid separator maintained at 30 atm and 373° C., in which a very small amount of liquid (i.e., 0.2 wt % of the refined soybean oil fed to the single wall-cooled reactor tube) was separated from a vapor phase. The vapor phase from the separator flowed upward to a single tube, adiabatic, fixed-bed reaction unit packed with a granulated 1 wt % Pt/SAPO-11 catalyst operated at an LHSV of 1.4 h⁻¹, 373-375° C., 30 atm, and an H₂/oil ratio of 550 NL/L. The diesel product from the adiabatic reaction unit was analyzed according to ASTM methods and its composition was measured by GC-MS. The results can be found in Table 5.

	TABLE 5

	Example 3

	Distillation Temperature
	ASTM D86
	IBP	143.8° C.
	10%	268.5° C.
	50%	293.6° C.
	90%	355° C.
	Up to 250° C.	5.1%
	Up to 350° C.	89.7%
	Cold Filter Plugging Point (CFPP)	−20° C.
	IP 309
	Lubricity (HFRR)	346 μm
	ISO 12156/1
	Flash Point	59° C.
	Kinematic Viscosity @ 40° C.	3.76 cSt
	ASTM D445
	Specific Gravity @ 15° C.	0.802 g/cm³
	ASTM D1298
	Composition, wt %
	Linear paraffins	20
	Branched paraffins	64
	Alkyl cyclohexane	7
	Alkyl benzene	7
	Olefins	2
	Acids	0.2

The diesel product according to Example 3 exhibited acceptable properties, including a lubricity of 346 μm.
The temperature of the adiabatic reaction unit following the vapor-liquid separator is set by the temperature of the vapor-liquid separator. Heat loss can cause a temperature drop in the vapor phase products from the tubular reaction unit. Assuming that heat loss is avoided, if the temperature of the vapor-liquid separator is low (i.e., lower than the temperature of the vapor phase products from the tubular reaction unit), the vapor phase products may undesirably condense to liquid prior to hydroisomerization in the adiabatic reaction unit. Therefore, the temperature of the vapor-liquid separator can be set such that the temperature of the vapor-liquid separator is close to the temperature of the tubular reaction unit, and more specifically, the temperature of the vapor phase products from the tubular reaction unit. Most of the heat of the hydrodeoxygenation and hydroisomerization reaction is generated in the tubular reaction unit, which can be a wall-cooled reactor. Accordingly, the reaction unit downstream of the vapor-liquid separator can be run adiabatically. The vapor-liquid separator, which can provide different conditions in the downstream adiabatic reaction unit than in the upstream tubular reaction unit, can also ensure that the downstream adiabatic reaction unit is run in vapor phase.
For example, the temperature of the adiabatic reaction unit following the vapor-liquid separator can be set in the range of about 350 to 400° C. or about 360 to 385° C. In particular, the temperature of the vapor-liquid separator in Example 3 was maintained at 373° C. and the temperature of the adiabatic reaction in Example 3 was operated at 373° C., to minimize condensation of vapor phase products to liquid prior to hydroisomerization in the adiabatic reaction unit. Thus, the vapor-liquid separator can be used to set the temperature of the adiabatic reaction unit following the vapor-liquid separator.
As noted above, the effluent from the single wall-cooled reactor tube is primarily in a vapor phase (e.g., vapor phase can comprise about 95 to 99.9 wt % of the effluent). The liquid separated from the vapor phase in the vapor-liquid separator can contain as much as 40 wt % acids. The catalyst contained in the reaction units is sensitive to coking and deactivation as a result of contact with heavy compounds (e.g., acids) in the liquid products. Thus, liquid products can negative affect selectivity of desired products and stability of the catalyst. Accordingly, separation of liquid from the vapor phase in the vapor-liquid separator (i.e., the vapor phase to be fed to the adiabatic reaction unit), protects catalyst in the adiabatic reaction unit and prevents deactivation thereof. Consequently, while catalyst in the upstream tubular reaction unit can be prone to deactivation as a result of contact with heavy compounds (e.g., acids) in the liquid products, separating liquid product in the vapor-liquid separator prior to the downstream adiabatic reaction unit can avoid the need to regenerate catalyst in the downstream adiabatic reaction unit. Thus, use of both tubular (e.g., single wall-cooled reactor tube or multi-tubular) and adiabatic reaction units, and a vapor-liquid separator disposed therebetween, allows for improved performance and stability of the catalyst, especially the catalyst contained within the adiabatic reaction unit. In particular, the life of the catalyst contained within the adiabatic reaction unit can be extended as a result of using a vapor-liquid separator disposed between the tubular and adiabatic reaction units.
While various embodiments have been described, it is to be understood that variations and modifications can be resorted to as will be apparent to those skilled in the art. Such variations and modifications are to be considered within the purview and scope of the claims appended hereto.

Claims

1. A process for producing a liquid fuel composition comprising:

providing oil selected from the group consisting of vegetable oil, animal oil, and mixtures thereof; and hydrodeoxygenating and hydroisomerizing the oil, wherein the hydrodeoxygenating and hydroisomerizing comprises:

feeding the oil to a tubular reaction unit containing a catalyst comprising an acidic component and a metal component;

feeding effluent from the tubular reaction unit to a vapor-liquid separator; and

feeding a vapor phase separated from the effluent from the tubular reaction unit to an adiabatic reaction unit comprising the same catalyst as in the tubular reaction unit comprising an acidic component and a metal component.

2. The process of claim 1, wherein the tubular reaction unit comprises a multi-tubular reaction unit.

3. The process of claim 1, wherein hydrodeoxygenating occurs in the tubular reaction unit and hydroisomerizing occurs in the adiabatic reaction unit.

4. The process of claim 1, further comprising recycling liquid separated from the effluent from the tubular reaction unit to the tubular reaction unit.

5. The process of claim 1, wherein the tubular reaction unit operates in trickle-bed mode.

6. The process of claim 1, wherein the adiabatic reaction unit comprises a single tube.

7. The process of claim 1, comprising operating the tubular reaction unit at conditions comprising:

a liquid hourly space velocity of 0.5 to 5 hr⁻¹;

a temperature of 300 to 450° C.;

a pressure of 10 to 60 atm; and

a H₂/oil ratio of 300 to 1200 NL/L.

8. The process of claim 1, wherein the vapor phase has a temperature of about 330 to 400° C.

9. The process of claim 1, comprising operating the adiabatic reaction unit at a temperature of about 350 to 400° C.

10. The process of claim 1, wherein the metal component is selected from the group consisting of platinum and palladium and the acidic component is selected from the group consisting of amorphous silica alumina, fluorided alumina, ZSM-12, ZSM-21, ZSM-22, ZSM-23, ZSM-35, ZSM-38, ZSM-48, ZSM-57, SSZ-32, ferrierite, SAPO-11, SAPO-31, SAPO-41, MAPO-11, MAPO-31, Y zeolite, L zeolite, and beta zeolite.

11. The process of claim 9, wherein the catalyst is Pt/SAPO-11.

12. The process of claim 10, wherein the catalyst is 0.5-1 wt % Pt/SAPO-11.

13. The process of claim 1, wherein the vegetable oil is selected from the group consisting of soybean oil, palm oil, corn oil, sunflower oil, jatropha oil, balanites oil, rapeseed oil, colza oil, canola oil, tall oil, safflower oil, hempseed oil, olive oil, linseed oil, mustard oil, peanut oil, castor oil, coconut oil, and mixtures thereof.

14. The process of claim 1, wherein the animal oil is selected from the group consisting of lard oil, tallow oil, train oil, fish oil, and mixtures thereof.

15. A reaction system for producing a liquid fuel composition comprising:

a tubular reaction unit containing a catalyst comprising an acidic component and a metal component;

an adiabatic reaction unit comprising the same catalyst as in the tubular reaction unit comprising an acidic component and a metal component; and

a vapor-liquid separator disposed between the tubular reaction unit and the adiabatic reaction unit.

16. The reaction system of claim 15, wherein the tubular reaction unit comprises a multi-tubular reaction unit.

17. The reaction system of claim 15, wherein the adiabatic reaction unit comprises a single tube.

18. The reaction system of claim 15, wherein the tubular reaction unit operates in trickle-bed mode.

19. The reaction system of claim 15, wherein the adiabatic reaction unit is located downstream of the tubular reaction unit.

20. The reaction system of claim 15, wherein the metal component is selected from the group consisting of platinum and palladium and the acidic component is selected from the group consisting of amorphous silica alumina, fluorided alumina, ZSM-12, ZSM-21, ZSM-22, ZSM-23, ZSM-35, ZSM-38, ZSM-48, ZSM-57, SSZ-32, ferrierite, SAPO-11, SAPO-31, SAPO-41, MAPO-11, MAPO-31, Y zeolite, L zeolite, and beta zeolite.