HK1215227B - Catalytic conversion of alcohols to hydrocarbons with low benzene content - Google Patents

Description

Catalytic conversion of alcohols to hydrocarbons with low benzene content

Government support

This invention was made with Government support under Contract No. DE-AC05-00OR22725 awarded by the U.S. Department of Energy. The U.S. Government has certain rights in this invention.

Field of the Invention

The present invention relates generally to the catalytic conversion of alcohols to hydrocarbons and, more particularly, to zeolite-based catalytic processes for such conversions.

Background of the Invention

The conversion of alcohols to hydrocarbons is generally not commercially viable. In fact, most industrial alcohols are produced from hydrocarbons. The conversion of alcohols to hydrocarbons is further inhibited by the substantial cost requirements of current conversion processes. Therefore, alcohols obtained by natural means (e.g., by biomass fermentation) would be a significantly cheaper feedstock for conversion processes.

However, a major obstacle to the application of current conversion processes for alcohols produced from biomass (i.e., bioalcohols) is the high concentration of water (and accompanying low concentrations of alcohol) typically produced in the fermentation streams produced in refineries where biomass is converted to alcohol. Current alcohol-to-hydrocarbon conversion processes are generally insufficient or not highly efficient at providing such conversions at such dilute alcohol concentrations and high water content. Instead, current alcohol-to-hydrocarbon conversion processes typically require pure alcohol (i.e., substantially free of water). Furthermore, the concentration and/or distillation of alcohol from the fermentation stream to accommodate current technology would be highly energy intensive and, therefore, would significantly offset the initial low cost gains of using bioalcohol.

Another significant obstacle to alcohol conversion processes is the unacceptably high levels of benzene produced in the hydrocarbon fraction, which typically do not exceed about 5%. However, for use as a fuel, environmental regulations require much lower benzene levels. For example, in the United States, the Environmental Protection Agency (EPA) enforces an upper limit of 0.62 vol% benzene content. Therefore, an alcohol conversion process that produces a hydrocarbon mixed feedstock with a substantially reduced benzene content provides further benefits.

Summary of the Invention

In one aspect, the present invention relates to a method for catalytically converting an alcohol into a hydrocarbon or hydrocarbon fraction (i.e., a mixture of hydrocarbons, or a "hydrocarbon mixed stock") having a reduced benzene content. In particular embodiments, the catalytic conversion can be achieved without the need for purification or concentration of the alcohol prior to the conversion reaction. For example, it has been discovered that the methods described herein can effectively convert a dilute aqueous solution of an alcohol, such as in a fermentation stream of a biomass fermentation reactor, to produce a hydrocarbon mixed stock having a reduced benzene content.

In particular embodiments, the method comprises converting the alcohol to a hydrocarbon fraction by contacting the alcohol with a metal-loaded zeolite catalyst component having catalytic activity for converting the alcohol to the hydrocarbon fraction under conditions suitable for converting the alcohol to the hydrocarbon fraction, and contacting the prepared hydrocarbon fraction with a benzene alkylation catalyst under conditions suitable for alkylating benzene to form an alkylated benzene product in the hydrocarbon fraction. In a first particular embodiment, the method is carried out by contacting the alcohol with a catalyst mixture comprising a metal-loaded zeolite catalyst and a benzene alkylation catalyst. In a second particular embodiment, the method is carried out in a two-step process, wherein in a first step, the alcohol is contacted with the metal-loaded zeolite catalyst to form a hydrocarbon fraction, and in a second step, the prepared hydrocarbon fraction is contacted with the benzene alkylation catalyst, wherein the metal-loaded zeolite catalyst and the benzene alkylation catalyst are unmixed (i.e., separate).

In another aspect, the present invention relates to a catalyst composition comprising a metal-loaded zeolite catalyst and a benzene alkylation catalyst, which is a mixture. In yet another aspect, the present invention relates to a one-zone or two-zone alcohol-to-hydrocarbon conversion reactor, wherein the catalyst composition is present in a mixture or separated form. In a particular embodiment of a two-zone reactor, a first zone contains a metal-loaded zeolite catalyst having catalytic activity for converting the alcohol to the hydrocarbon, and a second zone contains a benzene alkylation catalyst, wherein the two-zone reactor is configured such that the alcohol passes through the first zone to form hydrocarbons, and the generated hydrocarbons pass through the second zone to reduce their benzene content. The reactor may or may not include other reaction zones or processes, such as for fractionating or distilling the separated mixed feedstock, or for mixing with other mixed feedstocks.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 Gas chromatograms of product streams from ethanol conversion over V-ZSM-5, over a V-ZSM-5 + zeolite-Y mixture, and over zeolite-Y downstream of V-ZSM-5 (“layered V-ZSM-5 + zeolite-Y”).

Figure 2 shows a graph of the number of carbon atoms in the product stream from ethanol conversion on V-ZSM-5, on a mixture of V-ZSM-5 + zeolite-Y, and on zeolite-Y downstream of V-ZSM-5 ("layered V-ZSM-5 + zeolite-Y").

Detailed Description of the Invention

As used herein, the term "about" generally refers to within ±0.5, 1, 2, 5, or 10% of the specified value. For example, in the broadest sense, the phrase "about 100°C" can mean 100°C ± 10%, which means 100 ± 10°C or 90-110°C.

The term "alcohol" as used herein may refer to a single alcohol or a mixture of two or more alcohols, or may comprise an aqueous solution of one or more alcohols. The alcohols contemplated herein to be converted into hydrocarbons are primarily, but not necessarily, alcohols that can be prepared by fermentation processes (i.e., bioalcohols). The most notable examples of bioalcohols contemplated herein include ethanol, n-butanol (i.e., butanol), and isobutanol. In various embodiments, the alcohol may be ethanol, butanol, or isobutanol, or a combination thereof, as commonly found in fermentation streams. Other alcohols include n-propanol, isopropanol, sec-butanol, tert-butanol, n-pentanol, and isopentanol (isoamyl alcohol). In specific embodiments, the alcohol is an aqueous solution of an alcohol as found in a fermentation stream (i.e., a component of an aqueous solution in which the alcohol is an aqueous solution). In a fermentation stream, the concentration of the alcohol is typically no more than about 20% (volume/volume), 15%, 10%, or 5%. In some embodiments, the fermentation stream is directly contacted with the catalyst (typically, after filtering to remove solids) to convert the alcohol in the fermentation stream. In other embodiments, the alcohol in the fermentation stream is concentrated (e.g., to at least or no more than 20%, 25%, 30%, 40%, 50%, 60%, 70%, or 80%) before contacting the fermentation stream with the catalyst. In still other embodiments, the alcohol in the fermentation stream is selectively removed from the fermentation stream, such as by distillation, to produce substantially pure alcohol (e.g., at a concentration of at least 90% or 95%) as a feedstock. In still other embodiments, the alcohol is dehydrated to near-azeotropic ethanol (e.g., at a concentration of 92-94% alcohol) or completely dehydrated to 100% alcohol before contacting the catalyst.

As used herein, term " hydrocarbon " represents a single hydrocarbon compound or a mixture of two or more hydrocarbons. Although many types of hydrocarbon products can be prepared by this method, the hydrocarbon that this paper mainly considers is normally saturated, and more particularly, belongs to alkanes, which can be straight or branched or their mixture, particularly when said hydrocarbon product is used as fuel. Especially suitable alkanes herein comprise those alkanes that comprise at least 4,5 or 6 carbon atoms and are no more than 12,14,16,17,18 or 20 carbon atoms. Some examples of straight-chain alkanes comprise normal butane, n-pentane, normal hexane, normal heptane, normal octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, pentadecane, n-hexadecane, n-17decane, n-octadecane, n-nonadecane and n-eicosane. Some examples of branched alkanes include isobutane, isopentane, neopentane, isohexane, 3-methylpentane, 2,3-dimethylbutane, 2,2-dimethylbutane, 2-methylhexane, 3-methylhexane, 2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, 3,3-dimethylpentane, 2-methylheptane, and 2,2,4-trimethylpentane (isooctane). Some other hydrocarbon products that can be typically produced by the conversion process include olefins (i.e., alkenes, e.g., ethylene, propylene, n-butenes, and/or isobutylene) and aromatics (e.g., naphthalene, benzene, toluene, and/or xylenes).

The hydrocarbon product that this paper considers especially is the hydrocarbon mixture that is used as fuel or as the mixed stock in the fuel.The hydrocarbon mixture prepared herein preferably corresponds substantially to (for example, in component and/or property aspect) known petrochemical fuel, for example oil, or the fractionation effluent of oil.Some examples of petrochemical fuel include gasoline, kerosene, diesel oil and jet fuel (for example, JP-8).As the hydrocarbon fuel grade of existing use, the hydrocarbon mixture prepared herein can mainly or exclusively be made up of alkane, alkene, aromatic compound or their mixture in some embodiments.The hydrocarbon raw product prepared by described method is usually fractionated into different fuel grades by distillation, and each kind thereof is known in specific boiling point range.A special advantage of this method is that the present invention can prepare these substantially fuel grades that do not contain the pollutant (for example mercaptan) that needs to be removed in the oil refining process usually.In addition, by suitable regulating to catalyst and process conditions, the selective distribution of hydrocarbon can be obtained.

The hydrocarbon products can be used in a variety of applications, including, for example, as precursors for plastics, polymers, and fine chemicals. The methods described herein can advantageously produce a range of hydrocarbon products having a variety of properties, such as molecular weight (i.e., weight distribution of hydrocarbons), saturation or unsaturation (e.g., the ratio of alkanes to alkenes), and the level of side-chain or cyclic isomers. The methods can provide this level of diversity by suitable selection, such as, for example, catalyst composition (e.g., catalytic metal), catalyst amount (e.g., catalyst to alcohol precursor ratio), reaction temperature, and flow rate (e.g., LHSV).

The process described herein uses an alcohol-hydrocarbon conversion catalyst (e.g., a metal-loaded zeolite) and a benzene alkylation catalyst in combination. As further described below, the method uses the two catalysts in combination by using the two catalysts in a mixed (combined) or unmixed (separated) state. In the context of the present disclosure, the compositions of the two catalysts are different.

In one embodiment of the conversion method described herein, a two-stage process is used. In the first stage, the alcohol is first catalytically converted into hydrocarbons or hydrocarbon fractions by contacting the alcohol with a metal-loaded zeolite under conditions suitable for the conversion (particularly, temperature and choice of catalyst). In the second stage, the prepared hydrocarbons or hydrocarbon fractions are then contacted with a benzene alkylation catalyst under conditions suitable for alkylating benzene to form an alkylated benzene product from the benzene contained in the prepared hydrocarbon fraction. Other aromatic compounds that may be present in the hydrocarbon fraction (e.g., toluene, xylene, ethylbenzene, and naphthalene) may also be alkylated in the benzene alkylation process.

In the first and second stages, during the contacting of the alcohol with the metal-loaded zeolite catalyst and subsequently the hydrocarbon with the benzene alkylation catalyst, a suitable reaction temperature is independently used. The temperature in each stage can be the same or different. Typically, the reaction temperature is at least 100°C and not more than 550°C. In different embodiments, the reaction temperature of each process is exactly, about, at least, above, not more than or less than, for example, 100°C, 125°C, 150°C, 175°C, 200°C, 225°C, 250°C, 275°C, 300°C, 325°C, 350°C, 375°C, 400°C, 425°C, 450°C, 475°C, 500°C, 525°C or 550°C, or a temperature within a range bounded by any two of the above exemplary temperatures, for example, 100-550°C, 200-550°C, 300-550°C, 400-550°C, 450 ～550℃, 100～500℃, 200～500℃, 300～500℃, 350～500℃, 400～500℃, 450～500℃, 100～450℃, 200～450℃, 300～450℃, 350～450℃, 400～450℃, 100～425℃, 200～425℃, 300～425℃, 350～425℃, 375～425℃, 400～425℃, 100～400℃, 200～400℃, 300～400℃, 350～400℃ and 375～400℃.

Typically, an ambient pressure of about 1 atmosphere (i.e., normal pressure) is used, at least in the conversion processes described herein. However, in some embodiments, elevated or reduced pressures may be used for the conversion or alkylation processes. In typical embodiments, elevated pressures are used in alkylation processes. In various embodiments, the elevated pressure may be 1.5, 2, 3, 4, 5, 10, 12, or 15 atmospheres. In other embodiments, the pressure may be reduced to, for example, 0.5, 0.2, or 0.1 atmospheres for the conversion or alkylation processes, or for both the conversion and alkylation processes.

The catalyst and reactor can have any design known in the art for catalytic treatment of fluids or gases at high temperatures, such as a fluidized bed reactor. The process can be continuous or batch mode. In a special embodiment, the alcohol is injected into a heated reactor so that the alcohol evaporates quickly into a gas, which is then passed through the catalyst. In some embodiments, if the fermentation stream is directly used as a raw material without purification, the reactor design includes a boiler unit and a reactor unit. If the fermentation stream is distilled to concentrate ethanol, a boiler unit is usually not needed because the distillation process removes the dissolved solids in the fermentation stream. The boiler unit evaporates the liquid raw material into a gas before it enters the reactor unit and retains the dissolved solids.

Additional reaction zones or processes may or may not be included. For example, in some embodiments, the prepared hydrocarbon mixed stock can be fractionated, distilled, or otherwise separated into a narrower carbon range mixture after, during, or before reacting with the alkylation catalyst. In other embodiments, the prepared hydrocarbon mixed stock can be mixed or mixed into other hydrocarbon mixed stocks, or mixed with an alkylating agent (e.g., olefins, such as ethylene or alkenyl chloride or alkyl chloride) after, during, or before reacting with the alkylation catalyst. In other embodiments, after reacting with the alkylation catalyst, the hydrocarbon mixed stock or its separated or purified portion can be processed into new products, such as commercial or industrial related products derived from hydrocarbons, such as alkanes, olefins, alkylbenzenes, polycyclic aromatic hydrocarbons, alkylated polycyclic aromatic hydrocarbons, or polymers. In yet other embodiments, before or during contact with the metal-loaded zeolite catalyst, the alcohol can be concentrated, purified (e.g., by distillation), or mixed with other alcohols or solvents (e.g., water). Any of the aforementioned exemplary additional processes can be combined with the present process, typically by connecting the necessary equipment for the additional process to the necessary equipment for implementing the present process.

In another embodiment of the conversion process described herein, a direct process (single stage or single step) is used to directly prepare a hydrocarbon fraction with reduced benzene content under suitable circumstances, in which a mixture (combination) of ethanol and a metal-loaded zeolite catalyst and a benzene alkylation catalyst is contacted. The terms "mixture" or "combination" used herein generally refer to a solid solution of solid particles of the catalyst that is directly or approximately in contact with each other. Between similar and/or different compositions, the solid particles may not merge or fuse. For example, by merging the particles of each catalyst on a shared storage platform or support while keeping the two catalysts in separate locations, it is possible to determine that there is no solid solution of direct contact between the catalyst particles of different types. The term "approximate contact" generally refers to a distance between the two particles that is not greater than or less than 5 cm, 2 cm, 1 cm or 0.5 cm. As used herein, the term "particle" encompasses solid shapes of any suitable size, which can be nanoscale (e.g., 10, 20, 50, 100, 200, or 500 nm), microscale (e.g., 1, 2, 5, 10, 50, 100, or 500 microns), or macroscale (e.g., 1, 2, 5, 10, 20, or 50 mm), or a size within a range of values bounded by the aforementioned exemplary values.

In the single-step process, the hydrocarbons produced by the reaction of the alcohol and the metal-loaded zeolite react simultaneously with the alkylation catalyst contained in the combined catalyst as the hydrocarbons are formed. Any of the temperatures and other processing conditions described above for the two-stage process can be used in the single-step process. Furthermore, the single-step process may or may not include any one or more additional processes, such as those described above.

The alkylated benzene portion prepared from the reaction of the hydrocarbon fraction and the alkylation catalyst comprises one or a mixture of any alkylated benzene compounds prepared by an alkylation process. Some particular embodiments of alkylated benzene products include ethylbenzenes, isopropylbenzenes (e.g., cumene (isopropylbenzene), diisopropylbenzenes, and triisopropylbenzenes), and butylbenzenes. Typically, at least a portion of the alkylated benzene product is ethylated benzene, which can be, for example, mono-, di-, or tri-ethylated benzene. Ethylbenzenes are typically prepared by the reaction of benzene and ethylene, wherein ethylene is typically prepared during a conversion process. Similarly, other higher alkylbenzenes are typically prepared by reacting benzene with higher olefins (e.g., propylene, butenes, pentenes, hexenes) formed in a conversion process. Because other unsaturated or aromatic compounds other than benzene are also typically produced in the conversion process (e.g., toluene, xylene, trimethylbenzene, biphenyl, naphthalene, anthracene, phenanthrene, cyclobutene, cyclopentene and cyclohexene and methylated derivatives thereof), the alkylation process typically results in the production of other alkylated aromatic hydrocarbons and alkylated polycyclics (e.g., ethyltoluene, ethylxylene, ethylnaphthalene, ethylcyclobutene and ethylcyclopentene and methylated derivatives thereof). Any of the above aromatic or polycyclic compounds can be isolated and used as commercial or industrial related products. Alternatively, any of the above alkylated aromatic or polycyclic compounds can be further reacted (e.g., under alkylation conditions with an olefin feed) to form a related commercial or industrial product. Because cyclic unsaturated or aromatic compounds other than benzene are typically alkylated by the alkylation process used herein, it can be said that the process not only reduces the content of benzene, but also reduces the content of other non-alkylated cyclic unsaturated or aromatic compounds.

The term "reduced benzene content," as used herein, means that the benzene content of the hydrocarbon fraction after reaction with the alkylation catalyst is lower than the benzene content of the hydrocarbon fraction prior to reaction with the alkylation catalyst (in a two-stage process) or without reaction with the alkylation catalyst (in a one-stage process using a catalyst mixture). In various embodiments, the benzene content of the hydrocarbon fraction after reaction with the alkylation catalyst directly or with the two catalyst mixture is exactly, about, no more than, or less than, for example, 4, 3, 2, 1, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1% by volume of the hydrocarbon fraction. In particular embodiments, consistent with existing EPA regulations, the benzene content of the hydrocarbon fraction immediately after reaction with the alkylation catalyst is no more than or less than 0.62% by volume of the hydrocarbon fraction. In other embodiments, the benzene content is substantially or completely zero (e.g., no more than or less than 0.05%, 0.02%, 0.01%, or even 0%). In some embodiments, the term "reduced benzene content" also means "reduced non-alkylated cyclic unsaturated compounds" or "reduced non-alkylated aromatic compounds," wherein any exemplary volume percentage used to express benzene content may alternatively be considered the content of non-alkylated cyclic unsaturated compounds or non-alkylated aromatic compounds.

In some embodiments, above-mentioned conversion process combines with fermentation process, and wherein said fermentation process prepares the alcohol as the raw material of said conversion process.Described " combining " expression will be sent into the alcohol-to-converter or the zone of carrying out above-mentioned conversion process at the alcohol prepared in fermentation unit or zone, and processes at this.Preferably, in order to minimize preparation cost, said fermentation process is enough close to conversion unit or zone, perhaps comprises and is used for the alcohol through preparation being transferred to the suitable pipeline of conversion unit or zone, thus, does not need to transport said alcohol.In specific embodiment, the fermentation stream prepared in fermentation unit is directly transferred in the conversion unit, usually simultaneously before said stream contact catalyst solids are removed (usually by filtration or sedimentation) from feed stream.

In some embodiments, the fermentation process is carried out in an automatic fermentation unit, i.e., sugars prepared elsewhere are loaded into the fermentation unit to produce alcohol. In other embodiments, the fermentation process is part of a larger biomass reactor unit, i.e., biomass is broken down into fermentable sugars therein, which are then processed in a fermentation area. Biomass reactors and fermentation units are well known in the art. Biomass generally refers to lignocellulosic materials (i.e., plant materials), such as wood, grass, leaves, paper, corn husks, sugarcane, bagasse, nut shells. Typically, the conversion of biomass to ethanol is carried out by the following steps: 1) pre-treating the biomass under known conditions to release lignin and hemicellulosic materials in the cellulosic material; 2) decomposing the cellulosic material to generate fermentable sugar materials by the action of cellulases; and 3) fermenting the sugar materials, typically by the action of fermenting organisms, such as suitable yeasts.

In other embodiments, the alcohol is produced from a more direct sugar source, such as a plant-based sugar source, such as sugar cane or cereal starch (e.g., corn starch). Ethanol production from corn starch (i.e., corn starch ethanol) and ethanol production from sugar cane (i.e., sugar cane ethanol) currently represent some of the largest commercial ethanol production processes. It is contemplated herein to incorporate the conversion process into any of these large-scale ethanol production processes.

As used herein, the alcohol to hydrocarbon conversion catalyst comprises a zeolite portion and a metal supported on the zeolite (i.e., a "metal-loaded zeolite"). The zeolites contemplated herein can be any porous aluminosilicate structure known in the art to be stable under high temperature conditions (i.e., temperatures of at least 100°C, 150°C, 200°C, 250°C, 300°C, and higher, and not exceeding, for example, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, or 900°C). In specific embodiments, the zeolite is stable from at least 100°C to no more than 700°C. Typically, the zeolite is ordered by having a crystalline or partially crystalline structure, but amorphous forms are also useful. The zeolite can generally be described as a three-dimensional framework comprising silicate (SiO ₂ or SiO ₄ ) and aluminate (Al ₂ O ₃ or AlO ₄ ) units interconnected (i.e., cross-linked) by shared oxygen atoms.

The zeolites used in the conversion process can be microporous (i.e., having a pore size of less than 2 μm), mesoporous (i.e., having a pore size between 2 and 50 μm, or a subrange thereof), or a combination thereof. In several embodiments, the zeolite material is entirely or substantially microporous. By being entirely or substantially microporous, the pore volume derived from the micropores can be, for example, 100% or at least 95%, 96%, 97%, 98%, 99% or 99.5%, with the remaining pore volume derived from the mesopores, or in some embodiments, from macropores (pore size greater than 50 μm). In other embodiments, the zeolite material is entirely or substantially mesoporous. By being entirely or substantially mesoporous, the pore volume derived from the mesopores can be, for example, 100%, or at least 95%, 96%, 97%, 98%, 99% or 99.5%, with the remaining pore volume derived from the micropores, or in some embodiments, from macropores. In still other embodiments, the zeolite material contains a large number of both micropores and mesopores. By including a plurality of both micropores and mesopores, the pore volume derived from mesopores can be, for example, no more than, at least or exactly 50%, 60%, 70%, 80% or 90% and the remaining pore volume derived from micropores, or vice versa.

In various embodiments, the zeolite used in the conversion process is an MFI zeolite, a MEL zeolite, a MTW zeolite, an MCM zeolite, a BEA zeolite, a kaolin or a faujasite zeolite. Examples of some specific zeolites include ZSM zeolites (e.g., ZSM-5, ZSM-8, ZSM-11, ZSM-12, ZSM-15, ZSM-23, ZSM-35, ZSM-38, ZSM-48), X zeolite, Y zeolite, β zeolite and MCM zeolites (e.g., MCM-22 and MCM-49). The composition, structure, and properties of these zeolites are well known in the art and have been described in detail, as found, for example, in U.S. Patents 4,721,609, 4,596,704, 3,702,886, 7,459,413, and 4,427,789, the contents of which are incorporated herein by reference in their entireties.

The zeolite used in the conversion process can have any suitable silica-alumina ratio (i.e., SiO ₂ /Al ₂ O ₃ or "Si/Al"). For example, in various embodiments, the zeolite can have a Si/Al ratio of precisely, at least, less than, or no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 120, 150, or 200, or a Si/Al ratio within a range bounded by any two of the foregoing values. In specific embodiments, the zeolite has a Si/Al ratio of 1 to 45.

In a specific embodiment, the zeolite used in the conversion process is ZSM-5. ZSM-5 belongs to the class of zeolites containing pentasil rings, and all such zeolites are also contemplated. In a specific embodiment, the ZSM-5 zeolite is represented by the chemical formula Na _n Al _n Si _96-n O ₁₉₂ ·16H ₂ O, where 0<n<27.

Typically, the zeolite contains a certain amount of cationic species. As is well known in the art, the amount of cationic species is generally proportional to the amount of aluminum in the zeolite. This is because replacing silicon atoms with aluminum atoms of lower valence requires the presence of paired cations to establish charge balance. Some examples of cationic species include hydrogen ions (H ⁺ ), alkali metal ions, alkaline earth metal ions, and main group metal ions. Some examples of alkali metal ions that may be contained in zeolites include lithium ions (Li ⁺ ), sodium ions (Na ⁺ ), potassium ions (K ⁺ ), rubidium ions (Rb ⁺ ) and cesium ions (Cs ⁺ ). Some examples of alkaline earth metal ions that may be contained in zeolites include beryllium ions (Be ²⁺ ), magnesium ions (Mg ²⁺ ), calcium ions (Ca ²⁺ ), strontium ions (Sr ²⁺ ) and barium ions (Ba ²⁺ ) ^. Some examples of main group metal ions that may be included in the zeolite include boron (B ³⁺ ), gallium (Ga ³⁺ ), indium (In ³⁺ ), and arsenic (As ³⁺ ). In some embodiments, a combination of cationic species is included. The cationic species may be present in trace amounts (e.g., not exceeding 0.01% or 0.001%), or optionally, in substantial amounts (i.e., exceeding 0.01% by weight of the zeolite and not exceeding, for example, 0.1%, 0.5%, 1%, 2%, 3%, 4%, or 5%). In some embodiments, any one or more of the aforementioned classes or specific examples of cationic species are excluded from the zeolite.

The above-mentioned zeolite is loaded with a certain amount of catalytically active metal. The type and amount of the catalytic metal loaded into the zeolite are selected so that the generated loaded zeolite is catalytically active for converting alcohol into hydrocarbons under the above-mentioned conditions. Generally, the metal considered herein is in the form of a positively charged metal ion (i.e., a metal cation). These metals can be, for example, monovalent, divalent, trivalent, tetravalent, pentavalent or hexavalent. In some embodiments, the metal ion is (or includes) an alkali metal ion. In other embodiments, the metal is (or includes) an alkaline earth metal ion. In other embodiments, the metal is (or includes) a transition metal, such as one or more first-row, second-row or third-row transition metals. Some preferred transition metals include copper, iron, zinc, titanium, vanadium and cadmium. The copper ion can essentially be monovalent copper (Cu ⁺¹ ) or divalent copper (Cu ⁺² ), and the iron ion can essentially be divalent iron (Fe ⁺² ) or ferric iron (Fe ⁺³ ). The vanadium ion may be in any of its known oxidation states, such as V ⁺² , V ⁺³ , V ⁺⁴ and V ⁺⁵ . In other embodiments, the metal is (or includes) a catalytically active main group metal, such as gallium or indium. A single metal or a combination of metals may be loaded into the zeolite. In other embodiments, any one or more of the above metals are not included in the zeolite.

The metal loading in the zeolite can be any suitable amount, but is generally no more than about 2.5%, wherein the loading is expressed as the amount of metal by weight of the zeolite. In various embodiments, the metal loading is, exactly, at least, less than, or no more than, for example, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, or 2.5%, or a metal loading within a range bounded by any two of the above values.

In other aspects of the present invention, the zeolite catalyst can include at least one trivalent metal in addition to the one or more metals mentioned above. As used herein, the term "trivalent metal ion" is defined as a trivalent metal ion in addition to aluminum ion (Al ⁺³ ). Without wishing to be bound by any theory, it is believed that the trivalent metal is introduced into the zeolite structure. More specifically, it is believed that the introduced trivalent metal ion is combined with an appropriate number of oxygen atoms in the zeolite, i.e., as a metal oxide unit comprising a metal cation that is connected to the structure by an oxygen bridge. In some embodiments, the presence of the trivalent metal ion in conjunction with one or more other catalytically active metal ions can result in a combined effect that is different from the superposition effect when these ions are used alone. The effect primarily considered here is the ability of the catalyst formed to convert alcohol into hydrocarbons.

In some embodiments, only one type of trivalent metal ion is introduced into the zeolite in addition to aluminum. In other embodiments, at least two types of trivalent metal ions are introduced into the zeolite in addition to aluminum. In still other embodiments, at least three types of trivalent metal ions are introduced into the zeolite in addition to aluminum. In still other embodiments, specifically, two or three types of trivalent metal ions are introduced into the zeolite in addition to aluminum.

Each of the trivalent metal ions can be included in any suitable amount, for example, exactly, at least, less than, or no more than, for example, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, or 2.5%, or in an amount within a range bounded by any two of the above values. Alternatively, the total content of trivalent metals (excluding Al) can be limited to any of the above values. In some embodiments, one or more specific types, or all, of trivalent metal ions other than Al are not included in the catalyst.

In a first group of embodiments, at least one trivalent metal ion is selected from a trivalent transition metal ion. The one or more transition metals can be selected from any portion or selected portion of the following types of transition metals: Group IIIB (Sc), Group IVB (Ti), Group VB (V), Group VIB (Cr), Group VIIB (Mn), and Group VIIIB (Fe and Co) in the periodic table. Some examples of trivalent transition metal ions include Sc ⁺³ , Y ⁺³ , V ⁺³ , Nb ⁺³ , Cr ⁺³ , Fe ⁺³ , and Co ⁺³ . In other embodiments, the trivalent ion does not include all transition metal ions, or alternatively, does not include any one, two, or more types of transition metal ions or specific examples thereof given above. In specific embodiments, the trivalent transition metal ion includes Sc ⁺³ or Fe ⁺³ , or a combination thereof.

In a second group of embodiments, at least one trivalent metal ion is selected from trivalent main group metal ions. One or more of the main group metals can be selected from any portion or selected portion of the elements of Group IIIA (Group B) and/or Group VA (Group N) in the periodic table, excluding aluminum. Some examples of trivalent main group metal ions include Ga ⁺³ , In ⁺³ , As ⁺³ , Sb ⁺³ , and Bi ⁺³ . In other embodiments, the trivalent metal ions do not include all main group metal ions excluding aluminum ions, or alternatively, do not include any one, two, or more of the categories of main group metal ions listed above, or specific examples thereof. In specific embodiments, the trivalent main group metal ions include at least In ³⁺ .

In a third group of embodiments, at least one trivalent metal ion is selected from trivalent lanthanide metal ions. Some examples of trivalent lanthanide metal ions contemplated herein include La ⁺³ , Ce ⁺³ , Pr ⁺³ , Nd ⁺³ , Sm ⁺³ , Eu ⁺³ , Gd ⁺³ , Tb ^{+3 ,} Dy ⁺³ , Ho ⁺³ , Er+3, Tm ⁺³ , Yb ⁺³ , and Lu ⁺³ . In specific embodiments, the trivalent lanthanide metal ion is selected from one or a combination of La ⁺³ , Ce ⁺³ , Pr ⁺³ , and Nd ⁺³ . In more specific embodiments, the trivalent lanthanide metal ion is or includes La ⁺³ . In other embodiments, the trivalent metal ion does not include all lanthanide metal ions, or alternatively, does not include any one, two, or more classes of lanthanide metal ions or specific examples thereof provided above.

In a fourth group of embodiments, the zeolite comprises at least two trivalent metal ions selected from trivalent transition metal ions. Some combinations of trivalent transition metal ions contemplated herein include a combination of Sc ⁺³ and one or more other trivalent transition metal ions, or a combination of Fe ⁺³ and one or more other trivalent transition metal ions, or a combination of Y ⁺³ and one or more other trivalent transition metal ions, or a combination of V ⁺³ and one or more other trivalent transition metal ions.

In a fifth group of embodiments, the zeolite comprises at least two trivalent metal ions selected from trivalent main group metal ions. Some combinations of trivalent main group metal ions contemplated herein include combinations of In ⁺³ and one or more other trivalent main group metal ions, or combinations of Ga ⁺³ and one or more other trivalent main group metal ions, or combinations of As ⁺³ and one or more other trivalent main group metal ions.

In a sixth group of embodiments, the zeolite comprises at least two trivalent metal ions selected from trivalent lanthanide metal ions. Some combinations of trivalent lanthanide metal ions contemplated herein include a combination of La ⁺³ and one or more other trivalent lanthanide metal ions, or a combination of Ce ⁺³ and one or more other trivalent lanthanide metal ions, or a combination of Pr ⁺³ and one or more other trivalent lanthanide metal ions, or a combination of Nd ⁺³ and one or more other trivalent lanthanide metal ions.

In a seventh group of embodiments, the zeolite comprises at least one trivalent transition metal ion and at least one trivalent lanthanide metal ion. For example, in specific embodiments, at least one trivalent metal ion is selected from Sc ⁺³ , Fe ⁺³ , V ⁺³ and/or Y ⁺³ , and the other trivalent metal ion is selected from La ⁺³ , Ce ⁺³ , Pr ⁺³ and/or Nd ⁺³ .

In an eighth group of embodiments, the zeolite comprises at least one trivalent transition metal ion and at least one trivalent main group metal ion. For example, in specific embodiments, at least one trivalent metal ion is selected from Sc ⁺³ , Fe ⁺³ , V ⁺³ and/or Y ⁺³ , and the other trivalent metal ion is selected from In ⁺³ , Ga ⁺³ and/or In ⁺³ .

In a ninth group of embodiments, the zeolite comprises at least one trivalent main group metal ion and at least one trivalent lanthanide metal ion. For example, in specific embodiments, at least one trivalent metal ion is selected from In ⁺³ , Ga ⁺³ and/or In ⁺³ , and the other trivalent metal ion is selected from La ⁺³ , Ce ⁺³ , Pr ⁺³ and/or Nd ⁺³ .

In a tenth group of embodiments, the zeolite comprises at least three trivalent metal ions. The at least three trivalent metal ions may be selected from trivalent transition metal ions, trivalent main group metal ions and/or trivalent lanthanide metal ions.

In a specific embodiment, one, two, three or more trivalent metal ions are selected from Sc ⁺³ , Fe ⁺³ , V ⁺³ , Y ⁺³ , La ⁺³ , Ce ⁺³ , Pr ⁺³ , Nd ⁺³ , In ⁺³ and/or Ga ⁺³ . In a more specific embodiment, one, two, three or more trivalent metal ions are selected from Sc ⁺³ , Fe ⁺³ , V ⁺³ , La ⁺³ and/or In ⁺³ .

In a specific embodiment, the zeolite catalyst is or includes a pentasil zeolite composition loaded with any suitable metal as described above. In a more specific embodiment, the zeolite catalyst is or includes, for example, a mixture of copper-loaded ZSM5 (i.e., Cu-ZSM5), Fe-ZSM5, Cu, Fe-ZSM5 or Cu-ZSM5 and Fe-ZSM5. In other embodiments, the zeolite catalyst is or includes, for example, Cu-La-ZSM5, Fe-La-ZSM5, Fe-Cu-La-ZSM5, Cu-Sc-ZSM5 or Cu-In-ZSM5.

The above-mentioned zeolite catalyst is typically not coated with a film or layer comprising metal. However, as desired herein, the present invention may or may not include the situation that the above-mentioned zeolite catalyst is coated with a film or layer containing metal, as long as the film or layer does not substantially hinder the catalyst from being effectively used as a conversion catalyst. By coating, a film or layer is present on the surface of the zeolite. In some embodiments, the surface of the zeolite only represents its outer surface (that is, as defined by the zeolite catalyst outer contour area), and in other embodiments, the area of the zeolite represents or includes the inner surface of the zeolite, such as the area in the pores or ducts of the zeolite. The metal-containing film or layer can be used for, for example, to adjust the physical properties, catalytic efficiency or catalytic selectivity of the catalyst. Some examples of metal-containing surfaces include oxides and/or sulfides of alkali metals, alkaline earth metals and divalent transition or main group metals, provided that the surface metal is non-polluting to hydrocarbon products and harmless to the conversion process.

The metal-loaded zeolites described herein can be synthesized by any suitable method known in the art. The methods contemplated herein should preferably introduce the metal ions uniformly into the zeolite. The zeolite can be a single type of zeolite or a combination of different zeolitic materials.

In a specific embodiment, the catalyst described herein is obtained by, first, impregnating a zeolite with the metal to be loaded. The impregnation step can be achieved, for example, by treating the zeolite with a solution containing one or more salts of the metal to be loaded. The zeolite is treated with a metal-containing solution, which contacts the zeolite so that the solution is absorbed into the zeolite, preferably into the entire volume of the zeolite. Typically, in the preparation of a metal-loaded zeolite catalyst (e.g., Cu-ZSM5 or V-ZSM-5), an acidic zeolite form (i.e., H-ZSM5) or its ammonium salt (e.g., NH ₄ -ZSM-5) is used as a starting material, and metal ions (e.g., copper ions) are exchanged on the raw material. The details of the metal exchange process are well known in the art.

In one embodiment, the impregnation step is achieved by treating the precursor zeolite with a solution containing all of the metals to be loaded. In another embodiment, the impregnation step is achieved by treating the precursor zeolite with two or more solutions, wherein different solutions contain different metals or metal combinations. Each treatment of the precursor zeolite with an impregnation solution corresponds to a separate impregnation step. Typically, when more than one impregnation step is employed, drying and/or heat treatment steps are used between these impregnation steps.

The metal impregnation solution comprises at least one or more metal ions to be loaded into the zeolite, and a liquid carrier for dispersing the metal ions into the zeolite. These metal ions are generally in the form of metal salts. Preferably, these metal salts are completely dissolved in the liquid carrier. The metal salt comprises one or more metal ions ionically bonded to one or more paired anions. Any one or more of the above-mentioned metal ions can serve as the metal ion portion. The paired anion can be selected from, for example, halogen ( ^F- , ^Cl- , ^Br- or ^I- ), carboxylate (e.g., formate, acetate, propionate or butyrate), sulfate, nitrate, phosphate, chlorate, bromate, iodate, hydroxide, β-diketonate (e.g., acetylacetonate) and dicarboxylate (e.g., oxalate, malonate or succinate).

In a specific embodiment, the catalyst of the metal load is prepared by forming a slurry comprising zeolite powder and the metal to be introduced. The slurry is dried and fired to form a powder. The powder is then combined with an organic and/or inorganic binder and wet mixed to form a paste. The formed paste can be formed into any desired shape, for example, a rod-shaped, honeycomb-shaped or pinwheel-shaped structure is formed by extrusion. The extruded structure is then dried and fired to form the final catalyst. In other embodiments, the zeolite powder, metal and binder are all combined together to form a paste, which is then extruded and fired.

After impregnation of the zeolite, the metal-loaded zeolite is typically dried and/or subjected to a heat treatment step (e.g., a firing or calcining step). The heat treatment step serves to permanently incorporate the impregnated metal into the zeolite, for example, by replacing Al ⁺³ and/or Si ⁺⁴ and forming metal oxide bonds in the zeolite material. In various embodiments, the heat treatment step may be performed for a period of time, such as 15 minutes, 30 minutes, 1 hour, 2 hours, 6 hours, 12 hours, 24 hours, 30 hours, 36 hours, or 48 hours, or a period of time within a range thereof, at a temperature of at least 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, or 800°C, or a range thereof. In some specific embodiments, the heat treatment step is performed for at least two hours at a temperature of at least 500°C. In some embodiments, the heat treatment step includes a temperature ramp from a lower temperature to a higher temperature and/or from a higher temperature to a lower temperature. For example, the heat treatment step may include a temperature ramp from 100 to 700° C. at a rate of 1, 2, 5, or 10° C./min, or vice versa.

Typically, one or more heat treatment steps for preparing a loaded metal zeolite catalyst are performed under normal ambient pressure. However, in some embodiments, elevated pressures (e.g., greater than 1 atmosphere to no more than 2, 5, or 10 atmospheres) are employed, whereas in some embodiments, reduced pressures (e.g., less than 1, 0.5, or 0.2 atmospheres) are employed. Additionally, although heat treatment steps are typically performed under normal air environments, in some embodiments, oxygen is increased, oxygen is reduced, or an inert environment is used. Gases that may be included in the processing environment include, for example, oxygen, nitrogen, helium, argon, carbon dioxide, and mixtures thereof.

To provide a more descriptive example, a Cu-ZSM-5 catalyst can be prepared as follows: 2.664 g of hydrated copper acetate (i.e., Cu(OAc) ₂ ·6H ₂ O) is dissolved in 600 mL of deionized water (0.015 M), followed by the addition of 10.005 g of H-ZSM-5 zeolite. The slurry is stirred at 50° C. for approximately two hours. After cooling, the Cu-ZSM-5 (blue color) is collected by filtration, washed with deionized water, and then calcined at approximately 500° C. (10° C./min) in air for four hours.

The prepared Cu-ZSM-5 precursor can then be further impregnated with another metal, such as iron. For example, Cu-Fe-ZSM-5 can be prepared by the following method: 5 g of Cu-ZSM-5 is suspended in 25 mL of a 0.015 M Fe(NO ₃ ) ₃ aqueous solution, degassed with N ₂ , and then stirred at about 80° C. for about two hours. A brown solid is obtained after filtration, leaving a transparent, colorless filtrate. The product is then calcined in air at about 500° C. (2° C./min) for about two hours. The formed Cu-Fe-ZSM-5 catalyst typically contains about 2.4% Cu and 0.3% Fe. A large number of other metals can be loaded into the zeolite in a similar manner to prepare a variety of metal-loaded catalysts. By another method, CuFe-ZSM-5 can also be prepared using the incipient wetness method. In the method, a certain amount of Cu-SSZ-13 (e.g., 10 g) is pulverized with an appropriate amount of Fe(NO ₃ ) ₃ ·9H ₂ O (e.g., 0.3 g), and then water is added to just cover the surface of the Cu-SSZ-13. The color of the Cu-SSZ-13 typically changes slowly from green to yellow. The sample is typically allowed to dry in air and then calcined in air, usually at 500° C. (2° C./min) for about 4 hours to obtain light yellow CuFe-SSZ-13.

Typically, the zeolite catalysts described herein are in powder form. In a first set of embodiments, at least a portion or all of the powder particles have a size less than a micron (i.e., nanoscale particles). The nanoscale particles can have a particle size of, precisely, at least, no more than, or less than, for example, 1, 2, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, or 950 nanometers (nm), or a particle size within a range bounded by any two of the above values. In a second set of embodiments, at least a portion or all of the powder particles have a size equal to or greater than 1 micron. The micron-sized particles can have a particle size of precisely, at least, no more than, or less than, for example, 1, 2, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 microns (μm), or a particle size within a range bounded by any two of the aforementioned values. In some embodiments, single crystals or grains of the catalyst correspond to any of the sizes provided above, while in other embodiments, crystals or grains of the catalyst are agglomerated to provide agglomerated crystals or grains having any of the aforementioned exemplary sizes.

In other embodiments, the zeolite catalyst can be in the form of a film, coating or multilayer film or coating. The thickness of the coating or multilayer coating can be, for example, 1, 2, 5, 10, 50 or 100 microns, or in the range they form, or be no more than 100 microns of thickness. In other embodiments, the zeolite catalyst is in the form of non-granular (i.e. continuous) block solid. In more other embodiments, the zeolite catalyst can be fibrous or in the form of a mesh.

The benzene alkylation catalyst can be any benzene alkylation catalyst known in the art. In a one-step process using a catalyst mixture, to form the conversion solution and the alkylation catalyst, the benzene alkylation catalyst is generally solid and typically in particulate form. In a two-step process using two separate catalysts, the benzene alkylation catalyst can be any benzene alkylation catalyst known in the art, including solid and liquid (and solid-liquid) alkylation catalysts.

In a first embodiment, the benzene alkylation catalyst is a zeolite catalyst. Provided that the alkylation catalyst has a different composition than the conversion catalyst, any of the above-described zeolite catalysts that can have benzene alkylation activity can be used as the alkylation catalyst described herein. Examples of some zeolite-based alkylation catalysts include zeolite Y, Ca-zeolite Y, mordenite, MCM (e.g., MCM-22, MCM-41, MCM-48, MCM-49, MCM-56, MCM-58, or MCM-68), ZSM-5, ZSM-11, and zeolite beta catalysts, and combinations thereof, as well as phosphate-modified forms thereof. Zeolite-based alkylation catalysts are often in their ammonium (e.g., NH ₄ ⁺ ), hydride, or alkali metal salt forms, but heavier metal-supported forms (e.g., Al, Zr, Fe, and other metals listed above) can be used. In the special case of a ZSM-5 catalyst, the catalyst can be exchanged for one with H, La, Mg, Pt, or Zn.

In a second embodiment, the alkylation catalyst is a Friedel-Crafts type catalyst. Examples of some Friedel-Crafts type catalysts include mixtures of _AlCl3 and HCl (the alkylation process is typically carried out at temperatures below 135°C and under sufficient pressure to maintain the reactants in the liquid phase), composites of phosphoric acid and a solid binder material, such as diatomaceous earth and diatomaceous earth (the alkylation process is typically carried out in a fixed bed reactor at 180-240°C), hydrogen fluoride (HF) and boron trifluoride ( _BF3 ), the latter two of which may be in the gas phase, solution or adduct form (e.g., etherate). Other Friedel-Crafts catalysts include _SbCl5 , _FeCl3 and _AlBr3 . The alkylation process using a Friedel-Crafts catalyst may or may not further include an alkyl halide, which serves to alkylate benzene and other aromatic compounds.

The process conditions (eg, temperature and pressure) used with benzene alkylation catalysts are well known in the art. In some embodiments, the reaction conditions for treating the hydrocarbon fraction and the benzene alkylation catalyst can be the reaction conditions of any of the conversion processes provided above.

In a specific embodiment, the conversion catalyst and the alkylation catalyst are selected in such a way that the fraction of the terminal hydrocarbon product is adjusted to a higher boiling point fraction. The higher boiling point fraction is preferably in a form that closely resembles diesel or gasoline fuel.

When a mixture of catalysts is used, the alcohol conversion catalyst and the alkylation catalyst can be used in any suitable weight ratio (relative to the total amount of catalyst). In various embodiments, the alkylation catalyst comprises exactly, about, at least, more than, no more than, or less than, for example, 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, or 70 wt %, relative to the total weight of the catalyst mixture. The alkylation catalyst can also be included within a range bounded by any two of the above values, for example, 5-50 wt %.

Any of the above-described catalysts, if appropriate, may be mixed or attached to a support material. The support material may be a powder (e.g., having any of the above-described particle sizes), granules (e.g., particle sizes of 0.5 mm or greater), a block material such as a flow-through honeycomb monolith, a plate or multi-plate structure, or a corrugated sheet metal. If a honeycomb structure is used, the honeycomb structure may comprise any suitable cell density. For example, the honeycomb structure may have 100, 200, 300, 400, 500, 600, 700, 800, or 900 cells per square inch (cells/square inch) (or 62 to 140 cells/square centimeter) or greater. The support material is typically composed of a refractory composition, such as those comprising cordierite, mullite, alumina (e.g., α-alumina, β-alumina, or γ-alumina), or zirconia, or combinations thereof. Honeycomb structures are particularly, specifically described in, for example, U.S. Patents 5,314,665, 7,442,425 and 7,438,868, the contents of which are incorporated herein by reference in their entirety. When using corrugated or other types of metal sheets, these sheets can be stacked on top of one another, with the catalyst material loaded on these sheets simultaneously, thereby retaining passages that allow alcohol-containing fluids or hydrocarbon gases to flow. These layered sheets can also be formed into structures, for example, by bending these sheets to form cylinders.

Examples have been listed below for the purpose of illustration and to describe some specific embodiments of the present invention. However, the scope of the present invention is not intended to be limited in any way to the examples set out herein.

Example 1

Ethanol conversion over a mixture of V-ZSM-5 and zeolite-Y

A mixed catalyst was prepared by mechanically mixing 150 mg of V-ZSM5 and 50 mg of zeolite-Y, and the catalyst was loaded onto a tubular reactor. At 350° C. and atmospheric pressure, a 1.0 mL (LHSV of 2.93 h ^-1 ) flow of ethanol diluted with helium at a flow rate of 50 mL/min was passed through the catalyst mixture. The reaction was allowed to run for 60 min to ensure steady state, and the product stream was analyzed using GC-MS. FIG1 shows a chromatogram of the product stream with a retention time of 14-16 min. As a comparison, a chromatogram of the product stream from V-ZSM-5 is also shown. The dotted black line shows the position of the benzene peak, which is present in the product stream from the reaction using V-ZSM-5, but not in the product stream of the reaction using a mixture of V-ZSM-5 and zeolite-Y catalyst. Analysis of the product stream also shows that when zeolite-Y is mixed with V-ZSM-5, C ₃ -C ₈ hydrocarbons decrease and C ₉ -C ₁₀ hydrocarbons increase.

Example 2

Ethanol conversion on V-ZSM-5 with zeolite-Y downstream

The catalyst loading was configured in a manner such that 50 mg of zeolite-Y was loaded onto a 200 mg V-ZSM-5 downstream reactor. At 350 ° C and atmospheric pressure, an ethanol stream diluted with helium at a flow rate of 1.0 mL (2.93 h ^-1 ) was passed through the catalyst system. With this configuration, ethanol was converted into a hydrocarbon stream on V-ZSM-5, and the hydrocarbon stream was passed through zeolite-Y. The reaction was allowed to run for 60 min to ensure steady state, and the product stream was analyzed using GC-MS. FIG1 shows a chromatogram of the product stream with a retention time of 14-16 min. The dotted black line shows the position of the benzene peak, which is present in the product stream from the reaction using V-ZSM-5, but does not appear in the product stream of the reaction when zeolite-Y is downstream of the V-ZSM-5.

FIG2 shows the carbon number distribution for the ethanol conversion reaction over V-ZSM-5, over a mixture of V-ZSM-5 and zeolite-Y, and over zeolite-Y downstream of V-ZSM-5 (i.e., "layered V-ZSM-5 + zeolite-Y"). Analysis of the product stream shows that C4- _C8 hydrocarbons decrease and _C9 - _C10 hydrocarbons increase when zeolite-Y is downstream of V-ZSM-5, compared to the product stream using only V-ZSM- ₅ as the catalyst.

While there have been shown and described what are presently considered to be the preferred embodiments of the invention, those skilled in the art will appreciate that various changes and modifications will occur which fall within the scope of the invention as defined by the appended claims.

Claims (28)

1. A catalyst composition for converting an alcohol into a hydrocarbon fraction for use as fuel, the catalyst composition comprising (i) a vanadium-supported zeolite catalyst having catalytic activity for converting the alcohol into the hydrocarbon fraction, and (ii) a benzene alkylation catalyst; wherein the hydrocarbon fraction comprises olefins and/or alkanes having at least four carbon atoms, and (i) the vanadium-supported zeolite catalyst and (ii) the benzene alkylation catalyst are separate. 2. The catalyst composition of claim 1, wherein the zeolite comprises pentasilicone ring zeolite. 3. The catalyst composition of claim 2, wherein the pentasilicone ring zeolite comprises ZSM5. 4. The catalyst of claim 1, wherein the benzene alkylation catalyst is a zeolite catalyst having the activity of alkylating benzene. 5. The catalyst of claim 4, wherein the benzene alkylation catalyst is selected from zeolite Y, mordenite and MCM catalysts that have the activity of alkylating benzene. 6. The catalyst of claim 1, wherein the hydrocarbon fraction comprises alkanes having at least four carbon atoms. 7. The catalyst composition of claim 1, wherein the vanadium-supported zeolite catalyst contains at least one trivalent metal ion in addition to vanadium and aluminum. 8. A two-region alcohol-to-hydrocarbon conversion reactor, the conversion reactor comprising: a first region containing a vanadium-supported zeolite catalyst having catalytic activity for converting the alcohol into a hydrocarbon fraction for use as fuel; and a second region containing a benzene alkylation catalyst; wherein the hydrocarbon fraction comprises olefins and/or alkanes having at least four carbon atoms. 9. The alcohol-to-hydrocarbon conversion reactor of claim 8, wherein the zeolite comprises pentasilicone ring zeolite. 10. The alcohol-to-hydrocarbon conversion reactor of claim 9, wherein the pentasilicone ring zeolite comprises ZSM5. 11. The alcohol-to-hydrocarbon conversion reactor of claim 8, wherein the benzene alkylation catalyst is a zeolite catalyst with alkylating benzene activity. 12. The alcohol-to-hydrocarbon conversion reactor of claim 11, wherein the benzene alkylation catalyst is selected from zeolite Y, mordenite and MCM catalysts having the activity of alkylating benzene. 13. The alcohol-to-hydrocarbon conversion reactor of claim 8, wherein the hydrocarbon fraction comprises alkanes having at least four carbon atoms. 14. A method for converting an alcohol into a hydrocarbon fraction having a reduced benzene content, the method comprising: converting the alcohol into a hydrocarbon fraction by contacting the alcohol with a vanadium-supported zeolite catalyst having catalytic activity for converting the alcohol into the hydrocarbon fraction for use as fuel, under conditions suitable for converting the alcohol into the hydrocarbon fraction; and contacting the hydrocarbon fraction with a benzene alkylation catalyst to form an alkylated benzene product in the hydrocarbon fraction under conditions suitable for alkylating benzene, wherein the hydrocarbon fraction comprises olefins and/or alkanes having at least four carbon atoms. 15. The method of claim 14, wherein the alcohol is contacted with a mixture of the zeolite catalyst containing the supported vanadium and the benzene alkylation catalyst. 16. The method of claim 14, wherein, in the first step, the alcohol is contacted with the vanadium-supported zeolite catalyst to form a hydrocarbon fraction, and in the second step, the hydrocarbon fraction is contacted with the benzene alkylation catalyst, wherein the vanadium-supported zeolite catalyst and the benzene alkylation catalyst are separate. 17. The method of claim 14, wherein the zeolite comprises pentasilicone ring zeolite. 18. The method of claim 17, wherein the pentasilicone ring zeolite comprises ZSM5. 19. The method of claim 14, wherein the benzene alkylation catalyst is a zeolite catalyst having the activity of alkylating benzene. 20. The method of claim 19, wherein the benzene alkylation catalyst is selected from zeolite Y, mordenite, and MCM catalysts that have the activity of alkylating benzene. 21. The method of claim 14, wherein the hydrocarbon fraction, after treatment with the benzene alkylation catalyst, has no more than 0.62% benzene by volume of the hydrocarbon fraction. 22. The method of claim 14, wherein the alcohol comprises ethanol. 23. The method of claim 14, wherein the alcohol is a component whose aqueous solution concentration is not higher than about 20%. 24. The method of claim 23, wherein the alcohol is a component of the fermentation stream when in contact with the vanadium-supported zeolite catalyst. 25. The method of claim 14, wherein the hydrocarbon fraction can be used as fuel or as a component of a mixture of feedstocks used as fuel. 26. The method of claim 14, wherein the method is combined with a fermentation process, wherein the fermentation process produces the alcohol as a component of the fermentation stream, and the fermentation stream is contacted with the vanadium-loaded zeolite catalyst. 27. The method of claim 14, wherein the method is combined with a biomass reactor comprising a fermentation process, wherein the fermentation process produces the alcohol as a component of the fermentation stream, and the fermentation stream is in contact with the vanadium-loaded zeolite catalyst. 28. The method of claim 14, wherein the hydrocarbon fraction comprises alkanes having at least four carbon atoms.