The present invention relates to a process for the production of fuel components for motor vehicles of the gasoline type, by the alkylation, with one or more alcohols, of a mixture containing benzene, and the separation of a product which boils within gasoline boiling range, wherein the alkylation and separation take place in two different steps. The process is carried out in the presence of a zeolite belonging to the BEA family.

A substantial amount of benzene is no longer present in the final mixture, i.e. the mixture obtained at the end of the alkylation step, due to the alkylation of said substrate with the alcohol or alcohols used. The process also allows a fraction which boils within the diesel boiling range to be obtained.

A particularly preferred aspect is to use alcohols deriving from raw materials of an agricultural or vegetable origin.

The invention also relates to the gasolines obtainable with the process of the present invention, having a high octane number and improved characteristics from the point of view of environmental impact. The invention also relates to the diesel cuts obtainable with the process of the present invention, which can be used as components of diesel compositions.

The reduction of the benzene content in fuels for motor vehicles in recent years has been and still is the object of increasingly strict law regulations, due to the environmental problems deriving from the toxicity of benzene itself.

At the same time, environmental problems, linked to the so-called greenhouse effect induced by an increase in the concentration of carbon dioxide in the atmosphere, and energy problems deriving from the predictable exhaustion of fuels of a fossil origin have imposed and still impose the growing use of fuels deriving from renewable sources as raw materials of an agricultural or vegetable origin.

In recent years laws and regulations adopted in relation to problems of an environmental nature have severely limited the quantity of benzene tolerated in fuels for motor vehicles. As of January 1 ^st , 2000, for example, the European directive 98/70 and subsequent European directive 2003/17/CE have imposed a maximum content of 1% v/v of benzene in commercial gasolines (method EN 12177) . In the United States, the maximum content of benzene in gasolines allowed is currently established, on a national scale, at 1% v/v but as of 1.01.2011 this value will be further reduced to 0.62% v/v (EPA MSAT Febras) .

These regulations have had a considerable impact on refinery operations, especially in relation to the use of gasoline from reforming which represents the main component of the so-called "gasoline pool" and is characterized at the beginning by a high content of benzene and aromatic compounds in general, valuable components of gasoline due to their high octane number.

A gasoline from catalytic reforming typically contains about 25% in moles of benzene and about 50% in moles of other aromatic components .

Various strategies have been adopted each time for removing benzene from the reformed gasoline. The precursors of benzene (cyclohexane, , methylcyclopentane, hexane) can be removed at the beginning from the feedstock fed to the catalytic reforming, or the benzene contained in the reformate stream to be sent to the gasoline pool can be saturated by hydrogenation to cyclohexane . The benzene can be extracted (UDEX and Sulfolan processes) by extraction with a solvent . These methods are not without problems as they cause a loss in the octane number and a consumption/lower production of hydrogen on the part of the reformer. Hydrogen is a valuable by-product which is increasingly used in refineries, for example, in hydrocracking and hydrodesulfurization operations. Extraction with a solvent requires storage facilities and sales structures of the benzene on the market or its captive use for petrochemical plants which are not always available.

Alternatively, the alkylation of benzene, contained in the reformate, to alkylbenzenes , has been proposed, using olefins available in refineries, for example the ethylene and propylene present in the FCC gases . The reduction of the benzene content by means of alkylation has definite advantages such as an increase in the volume of gasoline produced and an increase in the octane number. This method however also has its problems, it requires, for example, the pretreatment of the FCC gases for the removal of the sulfur and nitrogen contaminants and the separation and concentration of olefins, and is still in the development phase as it has not been affirmed in consolidated commercial applications. The patent EP 796234, for example, describes a process for the alkylation of a reformate stream containing benzene and alkyl-aromatics with a hydrocarbon stream containing C2-C5 olefins in the presence of a zeolitic catalyst MCM-49. Patent 375547 describes the production of a fuel with a reduced benzene content and a high octane number starting from a light reformate distillation cut rich in benzene which is reacted with a cracking gas containing C2-C5 olefins on a zeolitic catalyst containing mordenite. EP 414590 describes an analogous process in which the light reformate cut, rich in benzene, is preliminarily put in contact at room temperature with the gas containing olefins, separating them from the cracking gas and concentrating them, before proceeding with the alkylation step. US 5,082,990 describes the reduction of the benzene content of a refinery stream by reaction with an olefinic stream in a reactive distillation column on fixed beds of zeolitic alkylation catalyst, for example a beta or Y zeolite. Patent US 5,336,820 describes a process for the alkylation of gasoline cuts rich in benzene with C2-C5 olefins in which the aromatic cut is put in contact in a first step with the more reactive C3-C5 olefins and in a second step with ethylene, using an alumino-silicate catalyst. The patent WO 200694008 describes an analogous process carried out in vapour phase on a series of two catalytic beds containing ZSM- 5 and MCM-22 zeolites.

Another very important aspect relates to the regulations adopted in recent years by the governments of the main industrialized countries and European Community aimed at promoting the production and use of biofuels .

This term refers to hydrocarbon compounds produced starting from renewable raw materials of an animal or, more frequently, an agricultural and vegetable origin, suitable for use as fuels for motor vehicles. There are various reasons for sustaining the diffusion of biofuels, ranging from the widely-shared request for a reduction in greenhouse gas emissions into the atmosphere, and in particular carbon dioxide, in accordance with the Kyoto protocol, the desire for reducing the energy dependence on producer countries of crude oil, improving supply security through diversification of the sources, to predictions of a future exhaustion of the availability of fossil fuels. Biofuels also guarantee various technical advantages such as the absence of sulfur and in general a cleaner combustion, with a reduction in polluting emissions in the combustion phase. The biofuels which are currently most widely-used are bioethanol in the gasoline field and biodiesel. The incidence of bioethanol on the total volume of gasoline used, for example, is about 3% on a world-wide scale. Through the directive 2003/30/CE, the European Union has defined a program for the development of the use of biofuels with a final objective of an overall use of 5.75% of biofuels, in energy terms, in 2010. Furthermore, new directives are about to be issued which should envisage a final use of biofuels equal to 10% in energy content within 2020.

The use of biofuels, however, is not without problems. Bioethanol, for example, has a lower calorific value with respect to gasoline (-37%) and increases its volatility, at the same time it can create problems of cold ignition and induces a lower tolerance to the presence of water (demixing) , so that the maximum amount of ethanol tolerated in gasoline can reach 10% for use in current engines. Higher quantities are tolerated only after more or less significant modifications to the engines or can even require vehicles constructed ad hoc . The European standard EN 228 envisages the use of ethanol in gasoline in an amount not higher than 5% by volume. An alternative to the use of bioethanol as such in gasoline consists in the production of ethyl-t-butylether (ETBE) . In the European Union, in fact, bioethanol is prevalently used in the form of ETBE, which has fewer problems of use and can be added, on the basis of the EU directive currently in force, in an amount of up to 15% by volume. ETBE is not miscible with water, it does not have logistic problems and does not increase the volatility of gasoline. The use of ETBE however also has its drawbacks, as its production is limited by the relative availability of the olefins (isobutene) used. It is consequently strategically and also economically important to find new upgradings of bioethanol in the field of the production of intermediates of industrial interest .

Corma et al . in Journal of Catalysis 207, 46-56

(2002) , describe the alkylation of benzene with ethanol or isopropanol, in the presence of ITQ-7 zeolite and beta zeolite. The reaction takes place at atmospheric pressure and beta zeolite, moreover, proves to be the catalyst which is more deactivated in presence of ethanol .

EP 1069099 describes an alkylation process of benzene with isopropanol under complete gas phase conditions, in the presence of beta zeolite as catalyst. EP 1069100 describes an alkylation process of benzene with isopropanol under liquid or mixed phase conditions, in the presence of beta zeolite as catalyst .

The processes described above for alkylation with isopropanol require the use of pure feeds and are aimed at obtaining equally pure products, they also require a careful calibration of the reaction conditions in order not to affect the activity of the catalyst due to the water formed by the alkylation reaction with isopropanol. In the case of zeolite-based catalysts, the negative effect due to the presence of water is in fact well-known, which is revealed with a lowering of the overall yield to cumene together with a more or less rapid deactivation of the catalyst itself.

These processes, moreover, must operate in excess of benzene, with respect to the alkylating agent, isopropyl alcohol, which consequently remains unconverted in the mixture resulting from the alkylation process. This is due to the necessity of pushing the equilibrium towards the products and also to the fact of minimizing the formation of water: in both processes the molar ratio between benzene and isopropanol ranges from 3 to 10 and preferably from 4 to 8. For all of these reasons, the processes of the prior art described above which use isopropanol were not considered as being suitable for being used directly in refineries.

US 2009/0211943 describes a process for the reduction of benzene in gasoline which comprises reacting benzene and an alcohol or an ether in a reactive distillation column, so that contemporaneously :

- the C6 hydrocarbons and benzene are separated from the C7+ hydrocarbons,

- the benzene at least partly reacts with an alcohol or an ester in the presence of an alkylation catalyst,

- and the alkylated products are recovered together with the C7+ hydrocarbons at the bottom of the distillation column, whereas the C6 hydrocarbons, the unconverted alcohol or ether and the water formed are recovered from the head of the column. Systems based on reactive distillation require an extremely complex management and very particular forming techniques of the catalysts. Reactive distillation separates the reaction products as they are formed, it therefore separates the products contemporaneously with the alkylation reaction. The products are consequently separated in the same step in which the reaction takes place. The water formed by the reaction is also removed as it is formed. The examples relate to the alkylation of benzene alone, and not refinery mixtures, and from the data provided in these examples, it seems that conversion and selectivity results cannot be calculated.

We have now found a process which allows a cut to be obtained, as product, to be used as fuel component for motor vehicles, with a high octane number and a reduced benzene content. The process also allows cuts to be obtained, which can be used as diesel components. At the same time, the process of the invention allows alcohols deriving from renewable sources of a vegetable or agricultural origin, to be exploited, as alkylating agents .

An object of the present invention therefore relates to a process for the alkylation of a mixture containing benzene which comprises reacting said mixture with one or more alcohols having the formula ROH, wherein R is an alkyl group, in the presence of a catalytic composition containing a zeolite belonging to the BEA family, and separating a product which boils within the boiling range of gasoline, wherein the alkylation and separation take place in two different steps .

The product which boils within the range of gasoline contains alkylbenzenes deriving from the alkylation, with one or more alcohols, of the benzene contained in the starting mixture .

In the process of the present invention, unlike what is described for processes effected in a reactive column, the alkylation reaction and separation of the products obtained from the reaction mixture do not take place simultaneously, and therefore the alkylation reaction takes place without the removal of the products, i.e. without the removal of the reaction products as they are formed contemporaneously with the reaction. The separation of the products obtained from the reaction environment takes place in a step subsequent to that of the reaction and consequently the alkylation reaction and the separation are effected in two different areas.

The sequence used allows a product to be obtained, which is not only impoverished in benzene, but enriched in alkylbenzenes, and possibly dialkyl-benzenes , useful as gasoline components. Poly-alkylbenzenes which can be used as components for diesel blends, are also obtained.

By using the process of the present invention, there is a reduction of the benzene content of mixtures containing it, obtaining a product which maintains an octane number at least equal to, and preferably higher than, that of the starting mixture.

The alcohol or alcohols which can be used in the process of the present invention have the formula ROH, wherein R is an alkyl group, preferably containing from 2 to 5 carbon atoms. Alcohols which can be conveniently used are therefore ethanol, isopropanol, n-propanol, n- butanol, iso-butanol, sec-butanol, ter-butanol, pentanol, and ethanol, iso-propanol and n-butanol are preferably used.

For the process of the present invention, all mixtures containing benzene, and possibly containing one or more alkyl-aromatic compounds with seven or more carbon atoms, such as, for example, toluene, ethylbenzene , xylenes and cumene, can be used.

The mixtures used can contain, in addition to benzene and C7+ alkyl-aromatic compounds, saturated compounds containing from 5 to 8 carbon atoms, such as, for example, isomers of pentane, hexane and heptane, and naphthenes, such as, for example, cyclopentanes and cyclohexanes.

Mixtures containing benzene and possibly alkylbenzenes which can be conveniently used in the process of the present invention can, for example, be mixtures from reforming, FCC cuts, light FCC naphtha, coker naphtha, pyrolysis cuts, straight run gasoline cuts, and mixtures thereof. Mixtures concentrated in benzene, deriving from these by distillation, can also be used.

In particular, reformate mixtures which are suitable for being treated in the process of the present invention are mixtures deriving from reforming processes, containing benzene, typically in a quantity of at least 5% by volume, normally at least 12% by volume, preferably from 20 to 60% by volume. The following fractions deriving from reforming can be distinguished: full range reformates, light cut reformates, heavy reformates and heart cut reformates. These fractions typically contain n-paraffins, isoparaffins , naphthenes and aromatic compounds. In addition to benzene, other aromatic compounds which can be present in the reforming mixtures are toluene, xylenes, ethylbenzene and cumene . Mixtures deriving from these by distillation which can enrich the benzene content can also contain 80% of benzene and can be conveniently used in the process of the present invention .

Mixtures containing benzene which can be used in the process of the present invention typically have an end boiling point of about 260°C, preferably 120°C, even more preferably ranging from 40 to 120 °C. In particular the light reformate has a boiling range varying from C5 to 121°C, and the full range reformate has a boiling range varying from C5 to 232 °C. The mixture resulting from the alkylation step contains a larger quantity of alkylbenzenes with respect to the starting mixture, substantially deriving from the alkylation of benzene, and in a smaller quantity from the alkylation of the possible alkylbenzenes already present in the mixture before the treatment .

The quantity of benzene in the mixture leaving the reactor is at least 30% moles, preferably 40%, lower with respect to that of the starting mixture.

The mixture obtained from the alkylation step in particular proves to contain alkyl-aromatic compounds and polyalkyl-aromatic compounds deriving from the alkylation of benzene, and from the alkylation of the C7+ alkyl aromatic compounds possibly already present in the starting cut, for example a reformate cut, such as for example toluene, xylenes and ethylbenzene . In particular, the compounds obtained, with reference to benzene, are mainly mono-alkylation and di-alkylation products of benzene, but the formation of tri- alkylation and tetra-alkylation products is also observed. In particular therefore, ethylbenzene and diethylbenzene deriving from the reaction of benzene with ethanol, cumene and di-isopropylbenzene deriving from the reaction of benzene with isopropanol, butyl- benzene and di-butyl-benzene deriving from the reaction of benzene with butanol, may be present for example in the final mixture, depending on the alcohol or alcohols used; ethyl toluene deriving from the reaction of toluene with ethanol, and cymene deriving from the reaction of toluene with isopropanol, may also be present .

The mixture deriving from the alkylation reaction is subjected to a separation treatment which can be effected with any of the known techniques, preferably by distillation. At least one product which boils within the gasoline boiling range, i.e. a fraction which has a boiling range within the range of gasoline, wherein said gasoline range varies from C5 to 210 °C, is isolated from the separation. The highest boiling fraction, i.e. the fraction which boils at a temperature higher than 210 °C, preferably higher than 210°C and lower than 350°C, can be used as diesel component.

The fraction which boils within the gasoline range preferably contains alkylation products of benzene having a number of carbon atoms not higher than 12 and more preferably not higher than 10. According to a particularly preferred embodiment, the fraction which boils within the gasoline range is selected from the range varying from C5 to 190 °C. In this latter case, the gasoline fraction can contain the corresponding mono-alkylation product of benzene, and, in the case of the use of ethanol, also the di-alkylation product. According to a particularly preferred embodiment, the gasoline fraction is selected from the boiling range of C7 to 190°C.

The octane number (RON) of the fraction which boils within the gasoline range is at least equal to that of the mixture used as starting feed, preferably at least

0.5 higher.

The highest boiling fraction, i.e. the fraction which boils at a temperature higher than 210 °C, comprises alkyl-aromatics containing more than 12 carbon atoms, deriving from the polyalkylation of benzene, and possibly from the alkylation of alkylbenzenes with at least seven carbon atoms present in the mixture containing benzene subjected to alkylation.

The fraction which boils within the diesel range,

1. e. the fraction which boils at a temperature higher than 210°C, will contain, in the case of the use of ethanol, as aromatic products, at least tri- ethylbenzene compounds; in the case of the use of alcohol having three or more carbon atoms, the di- alkylation products may also be contained in this fraction.

According to a preferred aspect, before proceeding with the separation of the gasoline fraction and diesel fraction, a phase containing water and unconverted alcohol is isolated by demixing. Cooling can be effected before the demixing.

In the fraction containing alkyl-aromatics which boils within the gasoline range (C5 - 210 °C) , the benzene content can be further reduced by cutting the lighter products during the separation, by distillation. The fraction which boils within the gasoline range can be used as gasoline component, blended for example with a non-reformate gasoline to obtain gasoline containing less than 1% of benzene. Due to the content of alkyl-aromatics having a high octane number, the product thus obtained will have a high octane number.

The alkylation process of the present invention is carried out under alkylation conditions of benzene, preferably at a temperature ranging from 150 to 300°C, even more preferably ranging from 180 to 280°C. The operating pressure varies from atmospheric pressure to 30 atm, preferably higher than atmospheric pressure, i.e. higher than 1 atm, even more preferably ranging from 2 to 20 atm.

The WHSV preferably ranges from 1 to 10 hours ^"1 .

A preferred aspect of the present invention is to operate at a benzene/alcohol molar ratio lower than 4, preferably higher than 0.4 and lower than 3 , even more preferably ranging from 0.5 to 2. When a mixture of alcohols is used, the molar ratios indicated above refer to the ratio between benzene and the sum of the moles of alcohols used.

An unexpected aspect of the present invention, with respect to the known art, is in fact the possibility of operating at very low benzene/alcohol (s) ratios: a high activity is unexpectedly obtained, whereas the catalyst does not suffer from the presence of water, whether it be formed during the process or fed together with the alkylating agent, if said alkylating agent is used in aqueous form.

The process of the present invention can be effected in gas phase, in liquid phase or in mixed phase. It is preferable to operate in gas phase or mixed phase .

In the process of the present invention, catalysts containing a zeolite belonging to the BEA family are used, preferably beta zeolite.

The beta zeolite used as component of the catalytic composition of the process according to the present invention, corresponds to that described in US 3,308,069, and is a porous crystalline material having the composition

[ (x/n) M (l±0.1-x) TEA ] A10 ₂ . ySi0 ₂ . wH ₂ 0

wherein n is the oxidation state of , x is less than 1, y ranges from 5 to 100, w from 0 to 4, M is a metal selected from those of groups IA, IIA, IIIA of the Periodic System, i.e. from transition metals and TEA is tetra-ethylammonium hydroxide. Beta zeolite is also described for example in US 4,642,226 and EP159846.

A preferred aspect of the present invention is for the beta zeolite to be in acid form, i.e. in the form in which the H ⁺ ion has partially or totally substituted the metallic cations initially present. This substitution is effected in accordance with the known methods by means of an exchange with ammonium ions, washing and subsequent calcination.

The catalytic system used in the present invention can comprise suitable ligands, for example oxides of groups IIIA, IVA and IVB. More preferably, the catalytic system can contain an oxide of Si or Al as a binding carrier. Even more preferably, the catalytic system can contain γ-alumina as binding carrier, γ-alumina is a known material and commercially available in the form, preferred for the purposes of the present invention, of bohemite or pseudobohemite precursors, subsequently transformed into γ-alumina during the preparation of the catalytic system, in the final calcination phase. The ligand is preferably used in a relative weight amount with respect to the catalytic system ranging from 5:95 to 95:5. A particularly preferable aspect of the present invention is to use the catalytic compositions containing beta zeolite described in EP 687500 and EP 847802.

In particular, EP 687500 describes a catalytic composition containing beta zeolite, as such or modified by the isomorphic substitution of the aluminium with boron, iron or gallium or by the introduction of alkaline or alkaline earth metals according to ion exchange procedures, and an inorganic ligand, in which the extrazeolite porosity is such as to be composed for a fraction of at least 25% of pores with a radius higher than 100 A.

In particular, EP 847802 describes a catalytic composition containing beta zeolite, as such or modified by the isomorphic substitution of the aluminium with boron, iron or gallium or by the introduction of alkaline or alkaline earth metals according to ion exchange procedures, and an inorganic ligand, in which the extrazeolite porosity is such as to be composed for a fraction of at least 25% of pores with a radius higher than 100 A, and characterized by a total volume of extrazeolite pores higher than or equal to 0.80 ml/g.

With respect to the reactor, the reaction can be carried out in continuous, in semi-continuous or batchwise, in a fixed bed, fluid bed, circulating bed catalytic reactor, and is preferably effected in a fixed bed reactor.

A preferred aspect of the present invention is to use, as alcohol, a bioalcohol or a mixture of bioalcohols, i.e. alcohols of a biological origin, preferably obtained by the fermentation of sugars deriving from biomasses. These alcohols do not contain either sulfur or other contaminants typical of products of a petroleum origin.

A preferred aspect of the present invention therefore relates to a process for the alkylation of a mixture containing benzene which comprises putting said mixture in contact with one or more alcohols ROH, wherein R is an alkyl group, in the presence of a catalyst containing a zeolite belonging to the BEA family, and separating a product which boils within the boiling range of gasolines, wherein the alkylation and separation take place in two different steps, and wherein the alcohol or alcohols ROH are obtained from biomasses, preferably lignocellulosic biomasses. In particular therefore, an object of the present invention relates to a process for the alkylation of a mixture containing benzene and alkyl-aromatics containing at least seven carbon atoms, which comprises :

1) subjecting the biomass, preferably lignocellulosic biomass, to transformation to obtain a feedstock which can be used for fermentation, said feedstock preferably being in the form of sugars,

2) subjecting the feedstock thus obtained to a treatment comprising one or more fermentation steps to obtain an alcohol or a mixture of alcohols,

3) alkylating a mixture comprising benzene with the alcohol or mixture of alcohols obtained in step (2) , in the presence of a catalyst containing a zeolite belonging to the BEA family, and separating a product which boils within the boiling range of gasolines, wherein the alkylation and separation take place in two different steps.

A preferred aspect of the present invention is to use ethanol as alkylating agent. According to a preferred aspect, in accordance with what is specified above with respect to bioalcohols, bioethanol is used, i.e. ethanol of a biological origin, preferably obtained by the fermentation of sugars deriving from biomasses .

Any of the known methods for obtaining ethanol from biomasses is suitable for providing ethanol which can be used in the present invention. In particular, it is used ethanol obtained from the fermentation of sugars deriving from biomasses, preferably lignocellulosic biomasses, according to any of the methods known to experts in the field. Even more in particular, ethanol is used, obtained by means of a process in which the biomass, preferably lignocellulosic, is transformed into a feedstock which can be used for fermentation, preferably in the form of sugars, and then subjected to fermentation.

Biomass is defined as being any substance having an organic, vegetable or animal matrix, which can be destined for energy purposes, for example, as raw material for the production of biofuels, or components which can be added to fuels.

In particular, lignocellulosic biomass is a complex structure comprising three main components: cellulose, hemicellulose, and lignin. Their relative quantities vary according to the type of lignocellulosic biomass used. Cellulose is the greatest constituent of lignocellulosic biomass and consists of glucose molecules (from about 500 to 10,000 units) bound to each other through a β-l, 4-glucoside bond. Hemicellulose, which is generally present in a quantity ranging from 10% by weight to 40% by weight with respect to the total weight of the lignocellulosic biomass appears as a mixed polymer, relatively short and branched, made up of both sugars with six carbon atoms and also sugars with five carbon atoms. Lignin is generally present in a quantity ranging from 10% by weight to 30% by weight with respect to the total weight of the lignocellulosic biomass.

The synthesis of ethanol from biomass is divided into various steps and comprises the conversion of the biomass into a feedstock which can be used for the fermentation (normally in the form of sugars) by applying one of the many technological processes available: said conversion forms the step which differentiates the various technological solutions in the synthesis of bioethanol . This step is followed by the fermentation of the intermediates of the biomass using bio-catalysts (micro-organisms such as yeast and bacteria) to obtain ethanol in a low-concentration solution. The fermentation product is then processed to obtain ethanol and by-products which can be used in the production of other fuels, chemical compounds, heat and electric energy.

In the first step, in order to optimize the transformation of the lignocellulosic biomass into products for energy use, subjecting said biomass to a treatment which separates the lignin and hydrolyzes the cellulose and hemicellulose to simple sugars such as, for example, glucose and xylose, which can then be subjected to fermentation processes to produce alcohols, is known.

Various processes can be used for this purpose, in particular hydrolysis, preferably acid, which is carried out in the presence of strong mineral acids, generally H ₂ S0 ₄ , HC1 or HN0 ₃ , diluted or concentrated, or enzymatic hydrolysis (SHF process) . The product obtained is then subjected to fermentation for the production of ethanol .

According to a particular aspect, the first and second step can be effected simultaneously, for example in the presence of the fungus T. reesei and yeast S. cerevisiae (SSF process) .

Processes for the production of ethanol from biomasses are described for example in US 5,562,777; US 2008/0044877; " Ethanol from ligninocellulosic biomass: technology, economics and process for the production of ethanol" F. Magalhaes, R.M. Vila Cha-Baptista, 4 ^th International Conference on Hands-on Science Development, Diversity and Inclusion in Science Education 2007; " Ethanol fermentation from biomass resources: current state and prospects" Y. Lin, S.Tanaka, Appl . Microbiol. Biotechnol . (2006) 69:627- 642; "Hydrolysis of ligninocellulosic materials for ethanol production: a review" Y. Sun, J. Cheng, Bioresource Technology, volume 83, Issue 1, May 2002, pages 1-11.

The ethanol obtained from step (2) is separated, for example, by means of distillation.

Another aspect of the present invention is to use propanol, preferably isopropanol, as alkylating agent. According to a preferred aspect, in accordance with what is specified above in general for bioalcohols, propanol of a biological origin is used, preferably obtained by the fermentation of biomasses, as described for example in US2009/0246842.

A further aspect of the present invention is to use butanol, preferably n-butanol, as alkylating agent, according to what is specified above in general for bioalcohols. According to a preferred aspect, biobutanol is used, i.e. butanol of a biological origin, preferably prepared by the fermentation of biomasses, according to the A.B.E.

(acetone/butanol/ethanol) process. The A.B.E. process, described for the first time in US 1,315,585, uses the bacterium Clostridium acetobutylicum. From this process, acetone, butanol and ethanol are obtained, which can be then separated by consecutive distillations. Variations and improvements of the A.B.E. process are described for example in US 5,753,474, US 5,192,673, and in Chang-Ho Park Biotechnol. Bioprocess Eng. 1996, 1, 1-8.

Another aspect of this invention is the use, as alkylating agent, of mixtures of alcohols, in particular mixtures containing at least two alcohols selected from ethanol, propanol, butanol. Mixtures of alcohols which can be conveniently used are those deriving from conversion processes of biomasses, such as, for example, the MixAlco process or the ABE process described above, or Fusel alcohol mixtures, obtained as by-product of the fermentation to ethyl alcohol, can be used.

The MixAlco process comprises both biological and chemical steps, and converts biodegradable material to carboxylic acids, then to ketones, and subsequently to mixtures of primary alcohols (ethanol, propanol, butanol) , and secondary alcohols (isopropanol, 2- butanol, 3-pentanol) . A method which allows these mixtures of alcohols to be obtained is for example that described in US 2008/0176301 which comprises subjecting a biomass to fermentation to obtain carboxylic acids or carboxylates , and hydrogen, separating the hydrogen and using it in a subsequent step for converting the carboxylates or carboxylic acids into alcohols.

Another process which can be adopted for obtaining mixtures of alcohols which can be used directly in the process of the present invention is the A.B.E. process, described above with respect to the production of biobutanol. If this mixture of alcohols is to be used, there is no need to isolate the single alcohol components .

Another mixture of alcohols which can be used in the process of the present invention is Fusel alcohol, a by-product of the fermentation of ethanol, containing 60-70% of amyl alcohol and smaller quantities of n- propyl and iso-butyl alcohol.

The following examples are provided for illustrating the invention claimed herein without however limiting the objectives in any way.

EXAMPLE 1

5 g of an extruded catalyst based on beta zeolite are charged into a tubular reactor (diameter of about 1.5 cm). The catalyst is prepared as described in Example 4 of EP 847 802, using the beta zeolite prepared as described in Example 3 of EP 847 802 and alumina in the form of bohemite . The catalyst has a porosity fraction with a radius higher than 100 A of over 35% and the extrazeolite pore volume is equal to 0.81 ml/g. The characteristics correspond to those indicated in Table I of EP 847 802. The catalyst is granulated and sieved into the fraction 0.8-1 mm.

The temperature of the reactor is brought to 250°C and the pressure to 10 atm, in a flow of N ₂ (5 Nl/hour) . The nitrogen flow is interrupted and 8.2 g/hour of a C6/C7 "heart cut" reformate mixture, having a boiling point within the range of 40-100 °C, containing 38.9% by weight of benzene, the remaining percentage consisting of C6 and C7 paraffins, are then fed to the reactor together with 1.9 g/hour of anhydrous ethanol, with a benzene/alcohol molar ratio of 1.0 and a total WHSV of 2.0 hours ^"1 .

The organic reaction effluent collected from the beginning to the 71 ^st operating hour, i.e. the effluent obtained after separation of the water formed during the reaction by demixing, is sent to a gaschromatograph to be analyzed. The quantity of water separated from the effluent mixture of the reaction proves to be equal to 7.3% by weight with respect to the weight of the total effluent mixture.

The data obtained from the gaschromatographic analysis show a conversion of benzene of 43.0% moles and a conversion of ethanol of 98.8% moles. The selectivity to alkyl-aromatics with respect to the ethanol is 93.3% moles and with respect to the benzene >99.6% moles, wherein alkyl-aromatics refer to ethyl- benzene, diethylbenzene and polyethyl-benzenes . In particular, the selectivity to ethyl-benzene and diethyl-benzene with respect to the benzene proves to be 64.0% moles.

Upon subjecting the organic effluent of the reaction to distillation, a fraction boiling within the range of 100 a 210 °C is separated, which can be used as component of gasolines, and a fraction which boils from a temperature higher than 210°C to 320°C which can be used as diesel component .

EXAMPLE 2

A test is carried out under the same conditions and with the same catalyst as Example 1, feeding to the reactor, 7.0 g/hour of a C6/C7 "heart cut" reformate mixture, having a boiling point within the range of 40- 100 °C, containing 39.1% by weight of benzene, the remaining percentage consisting of C6 and C7 paraffins, and 2.0 g/hour of aqueous ethanol at 95% by weight, with a benzene/alcohol molar ratio of 0.8 and a total WHSV of 1.8 hours ^"1 .

The organic effluents of the reaction are collected periodically over 175 operating hours and, after separation of the reaction water by demixing, are sent to a gaschromatograph to be analyzed.

The average quantity of water separated from the effluent mixture of the reaction proves to be equal to 9.2% by weight with respect to the weight of the total effluent mixture.

The data obtained from the gaschromatographic analysis show an average conversion of benzene of 40.0% moles and a conversion of ethanol of 95.6% moles. The average selectivity to alkyl-aromatics with respect to the ethanol is 87.8% moles and with respect to the benzene >99.6% moles, wherein alkyl-aromatics refer to ethyl-benzene , diethylbenzene and polyethyl-benzenes . In particular, the average selectivity to ethyl-benzene and diethyl-benzene with respect to the benzene proves to be 62.9% moles.

Upon subjecting the organic effluent of the reaction to distillation, a fraction boiling within the range of 100 a 210 °C is separated, which can be used as component of gasolines, and a fraction which boils from a temperature higher than 210°C to 320°C which can be used as diesel component .

EXAMPLE 3

The test of Example 2 is continued, feeding, at 383 operating hours, all the operative conditions remaining unvaried, 7.2 g/hour of the same C6/C7 "heart cut" reformate mixture as Example 2, containing 39.1% by weight of benzene, the remaining percentage consisting of C6 and C7 paraffins, and 1.7 g/hour of aqueous ethanol at 90% by weight, with a benzene/alcohol molar ratio of 1.1 and a total WHSV of 1.8 hours ^"1 .

The organic effluents of the reaction are collected periodically up to 580 operating hours and, after separation of the reaction water by demixing, subjected to gaschromatographic analysis.

The average quantity of water separated from the effluent mixture of the reaction proves to be equal to 6.7% by weight with respect to the weight of the total effluent mixture.

The data obtained from the gaschromatographic analysis show an average conversion of benzene of 28.9% moles and a conversion of ethanol of 81.9% moles. The average selectivity to alkyl-aromatics with respect to the ethanol is 86.1% moles and with respect to the benzene >99.5% moles, wherein alkyl-aromatics refer to ethyl-benzene, diethylbenzene and polyethyl-benzenes .

In particular, the average selectivity to ethyl-benzene and diethyl-benzene with respect to the benzene proves to be 70.8% moles.

Upon subjecting the organic effluent of the reaction to distillation, a fraction boiling within the range of 100 a 210 °C is separated, which can be used as component of gasolines, and a fraction which boils from a temperature higher than 210°C to 320°C which can be used as diesel component .

EXAMPLE 4

The test of Example 3 is continued, feeding, at 581 operating hours, all the operative conditions remaining unvaried, 7.6 g/hour of the same C6/C7 "heart cut" reformate mixture as Example 2, containing 39.1% by weight of benzene, the remaining percentage consisting of C6 and C7 paraffins, and 1.7 g/hour of aqueous ethanol at 80% by weight, with a benzene/alcohol molar ratio of 1.25 and a total HSV of 1.9 hours ^"1 .

The results of the gaschromatographic analysis of the organic reaction effluents periodically collected up to 726 operating hours, after separation of the reaction water, show an average conversion of benzene of 27.9% moles and a conversion of ethanol of 77.1% moles. The average selectivity to alkyl-aromatics with respect to the ethanol is 76.6% moles and with respect to the benzene >99.5% moles, wherein alkyl-aromatics refer to ethyl-benzene, diethylbenzene and polyethyl- benzenes. In particular, the average selectivity to ethyl-benzene and diethyl-benzene with respect to the benzene proves to be 73.4% moles.

The average quantity of water separated from the effluent mixture of the reaction proves to be equal to 7.7% by weight with respect to the weight of the total effluent mixture.

Upon subjecting the organic effluent of the reaction to distillation, a fraction boiling within the range of 100 a 210 °C is separated, which can be used as component of gasolines, and a fraction which boils from a temperature higher than 210°C to 320°C which can be used as diesel component .

EXAMPLE 5

A test is carried out in the same reactor and with the same catalyst as Example 1, at a temperature of 190°C and a pressure of 10 atm, feeding to the reactor 6.8 g/hour of a C6/C7 "heart cut" reformate mixture and 1.2 g/hour of isopropanol, with a benzene/alcohol molar ratio of 1.67 and a total WHSV of 1.6 hours ^"1 .

The C6/C7 mixture contains 37.6% by weight of benzene and 5.2% of toluene, the remaining percentage consisting of C6 and C7 paraffins.

The organic effluent of the reaction collected between the 21 ^st and 27 ^th operating hour, after separation of the reaction water, is subjected to gaschromatograph analysis.

The quantity of water separated from the effluent mixture of the reaction proves to be equal to 4.5 % by weight with respect to the weight of the total effluent mixture .

The data show a conversion of benzene of 43.7% moles, a conversion of toluene of 31.8% moles and isopropanol of 98.5% moles. The selectivity to alkyl- aromatics with respect to the isopropanol is 83.6% moles, with respect to the benzene and toluene >99.5% moles, wherein alkyl-aromatics refer to the products isopropyl -benzene, di-isopropyl-benzene, poly- isopropyl-benzene, iso-propyl-toluene, di-isopropyl- toluene .