WO2011128742A1

WO2011128742A1 - Process for the production of liquid hydrocarbons with a low content of aromatic compounds

Info

Publication number: WO2011128742A1
Application number: PCT/IB2011/000694
Authority: WO
Inventors: Giuseppe Paparatto; Stefano Ramello; Roberto Buzzoni; Daniele Bianchi
Original assignee: Eni S.P.A.
Priority date: 2010-04-15
Filing date: 2011-03-30
Publication date: 2011-10-20
Also published as: ITMI20100648A1; IT1400226B1

Abstract

Process for the production of liquid hydrocarbons with a low content of aromatic compounds which comprises putting an aqueous mixture including at least one alcohol having from 2 to 4 carbon atoms in contact with at least one catalyst selected from zeolites having a silica/alumina molar ratio (SAR) ranging from 100 to 500, preferably ranging from 200 to 300. The liquid hydrocarbon thus obtained can be subsequently subjected to hydrogenation for the production of gasolines, of kerosene (jet fuel), or of gas oils.

Description

PROCESS FOR THE PRODUCTION OF LIQUID HYDROCARBONS WITH A LOW CONTENT OF AROMATIC COMPOUNDS

The present invention relates to a process for the production of liquid hydrocarbons with a low content of aromatic compounds .

More specifically, the present invention relates to a process for the production of liquid hydrocarbons with a low content of aromatic compounds which comprises putting an aqueous mixture including at least one alcohol having from 2 to 4 carbon atoms in contact with at least one catalyst selected from zeolites having a specific silica/alumina molar ratio (SAR) .

The liquid hydrocarbon thus obtained can be subsequently subjected to hydrogenation for the production of gasolines, of kerosene (jet fuel), or of gas oils.

A reduction in oil reserves on the one hand, and the continuous increase in consumptions of oil products on the other, require a search for and exploitation of new raw materials alternative to petroleum and the im- plementation of new technologies for their production. This is particularly true in the field of fuels for civil use, i.e. fuels used in any type of transport such as, for example, air, ship, automobile, which are responsible for the consumption of over 60% of ex- tracted oil. In order to slow down the consumption of extracted oil, it is therefore necessary to develop new technologies directed towards the production of fuels starting from sources alternative to oil.

It is known in the art that alternative sources such as, for example, coal and natural gas, typically methane, can be transformed by means of partial oxidation or steam reforming processes into the so-called synthesis gas (syngas) , which is a combination of hy- drogen (H₂) and carbon monoxide (CO) . The synthesis gas (syngas) can be subsequently transformed into hydrocarbons (typically into a mixture of gaseous hydrocarbons, liquid hydrocarbons and waxes, having a number of carbon atoms ranging from 1 to 100 or more, and having different molecular weights) through the Fischer- Tropsch reaction. This reaction is generally carried out in the presence of catalysts containing cobalt, iron, ruthenium and/or nickel. Alternatively, the synthesis gas (syngas) can be transformed, with a high yield, into methanol and/or dimethyl ether, generally operating in the presence of catalysts containing zinc, chromium and/or copper.

It is also known that oxygenated compounds such as methanol and/or dimethyl ether can be converted into gasoline with a high octane number and with a high content of aromatic compounds by means of the catalytic conversion in the presence of zeolites, in particular, ZSM-5 zeolite, according to the so-called "methanol to gasoline" (MTG) process, described, for example, in American patents US 3,894,103, US 3,894,104, US 3,894,106, US 3,894,107, US 4,035,430, US 4,058,576. The gasoline obtained with this process, however, is generally characterized by a high content of aromatic compounds, quite higher than 30% by weight with respect to the total weight of the compounds contained in said gasoline and also, among aromatic compounds, by a high content of durene (1 , 2 , 4 , 5-tetramethylbenzene) , a compound which is undesired due to its high melting point which causes its tendency to separate from the gasoline with consequent problems when used for motor vehicles .

The most recent regulations envisage a limitation in the content of aromatic compounds in gasoline. For this reason, the gasoline obtained with the "methanol to gasoline" (MTG) process, is generally treated to reduce the content of said aromatic compounds and durene as described, for example, in American patent US 4,304,951, with a consequent technical and economical burden.

Furthermore, with the "methanol to gasoline" (MTG) process, it is generally difficult to obtain kerosene and/or gas oils, for whose production this process cannot therefore represent an alternative to the Fischer- Tropsch reaction described above.

Efforts have therefore been made in the art to overcome the above problems .

Processes are known, for example, which provide a first step in which the methanol and/or the dimethyl ether are selectively converted, in the presence of a zeolite, in particular ZSM-5 zeolite, to light olefins having from 2 to 5 carbon atoms (e.g., ethylene, propylene) , and a second step in which said light olefins are converted to gasolines, kerosene and/or gas oils, by means of oligomerization and/or hydrogenation. Proc- esses of this type are described, for example, in American patents US 4,025,576, US 4,476,338, US 4,482,772, US 4,497,968, US 4,506,106, US 4,543,435, US 4,547,602, US 4,579,999, US 4,689,205, US 4,899,002, US 4,929,780, US 5,045,287, US 5,177,279.

Also the above processes, however, can have various drawbacks, in particular in relation to the fact that the effluent deriving from the first step comprising light olefins having from 2 to 5 carbon atoms must gen- erally be subjected to onerous separation and compression operations before being sent to the second oli- gomerization and/or hydrogenation step.

Among alternative sources, in addition to those reported above, biomasses are of particular interest, which represent a "clean" raw material due to their negligible content of sulfur, nitrogen and ashes which consequently produce lower emissions of nitrogen oxides (NO_x) , of sulfur oxides (SO_x) , and of particulate (PM) , with respect to traditional fuels as described, for ex- ample, by Zhang Qi et al . , in: "Energy Conversion and Management" (2007), Vol. 48, pages 87-92. Furthermore, the specific emission of carbon dioxide (C0₂) is in fact null as the carbon dioxide (C0₂) released by the biomasses is quantitatively recycled from the plants by means of photosynthesis.

Processes capable of using the alcohols deriving from the treatment of biomasses such as, for example, fermentation, pyrolysis, flash pyrolysis, are known in the art . Huber et al . , for example, in: "Chemical Reviews" (2006), Vol. 106(9), pages 4044-4098, describe the possibility of transforming compounds which can derive from biomasses, such as, for example, alcohols, phe- nols, aldehydes, ketones, acids, and mixtures thereof, into precursors of gasolines, with the use of zeolitic catalysts (e.g., HZSM-5) .

Gayubo et al . , for example, in: "Industrial & Engineering Chemistry Research" (2004), Vol. 43, pages 2610-2618, describe a process for the transformation of oxygenated compounds (e.g., 1-propanol, 2-propanol, 1- butanol, 2-butanol, phenol and 2 -methoxyphenol) deriving from the flash pyrolysis of biomasses of a vegetable origin, into precursors of gasolines such as, for example, light olefins, with the use of zeolitic catalysts (e.g., HZSM-5). Low conversions, the formation of coke and significant problems relating to the deactivation of the catalyst have been observed, however.

Ruwet et al. , in "Bulletin des Societe Chimiques Beiges" (1987), Vol. 96, No. 4, pages 281-292, describe a process for the production of olefins starting from 1-butanol, pure, or from an aqueous mixture of ace- tone/butanol/ethanol (ABE) deriving from the fermentation of sugars obtained from biomass, in the presence of various types of basic catalysts containing phosphates (B-PO₄, Al-P0₄, Ca-Ni-P0₄) and of an acid catalyst containing alumina (γ-Α1₂0₃) . A decrease in the catalytic activity of both said basic catalysts and said acid catalyst, has been observed, however, in par- ticular when an aqueous mixture of ace- tone/butanol/ethanol (ABE) is used, this decrease probably being due to the presence of a high quantity of water in said mixture.

International patent application WO 2007/149397 describes a process for the production of at least one butene which comprises putting a mixture including 1- butanol and at least about 5% of water (by weight with respect to the total weight of water plus 1-butanol) in contact with at least one acid catalyst, operating at a temperature ranging from about 50°C to about 450°C and at a pressure ranging from about 0.1 MPa to about 20.7 Pa, to obtain a reaction product comprising at least one butene, and recovering said butene. Said mixture can derive from a fermentation broth. Said butene can be converted to iso-alkanes, alkyl-substituted aromatic compounds, iso-octanes, iso-octanols and ethers, which can be used as such as fuels for motor vehicles, or as additives for fuels for motor vehicles.

The processes described above, however, are not capable of directly providing mixtures of liquid hydrocarbons .

The Applicant therefore considered the problem of finding a process for the direct production of liquid hydrocarbons, in particular of liquid hydrocarbons with a low content of aromatic compounds, from aqueous mixtures of alcohols with a low number of carbon atoms.

The Applicant has now found that by using a zeolite having a specific silica/alumina (SAR) molar ratio, as catalyst, it is possible to directly obtain liquid hydrocarbons, in particular liquid hydrocarbons with a low content of aromatic compounds, from aqueous mixtures of alcohols having a low number of carbon atoms.

The use of said zeolite allows a high conversion of alcohols to be obtained (i.e. a conversion higher than or equal to 99% by weight with respect to the total weight of the alcohols contained in said aqueous mixtures) and a high yield of liquid hydrocarbons, in par- ticular C₅₊ liquid hydrocarbons with a low content of aromatic compounds (i.e. a yield higher than or equal to 65% by weight, said yield being calculated with respect to the total weight of the hydrocarbon component (i.e. alcohol (s) and, optionally, acetone) present in said aqueous mixtures.

Furthermore, the use of said zeolite allows aqueous mixtures of acetone/butanol/ethanol (ABE) deriving from the fermentation of biomasses, to be used. Said zeolite in fact is not deactivated by the presence of acetone. It should be pointed out, moreover, that the acetone present in said mixtures, in addition to not causing the deactivation of said zeolite, does not form alcoholic condensation products such as, for example, oxygenated sludge which can be easily transformed into precursors of coke.

Furthermore, the use of said zeolite makes it possible to operate in the presence of high quantities of water (i.e. quantities of water higher than or equal to 10% by weight with respect to the total weight of said aqueous mixtures) : said zeolite, in fact, is not deactivated by the presence of high quantities of water.

The use of said zeolite, moreover, allows the oli- gomerization step to be avoided.

An object of the present invention therefore relates to a process for the production of liquid hydrocarbons with a low content of aromatic compounds which comprises putting an aqueous mixture including at least one alcohol having from 2 to 4 carbon atoms in contact with at least one catalyst selected from zeolites having a silica/alumina molar ratio (SAR) ranging from 100 to 500, preferably ranging from 200 to 300.

For the purposes of the present invention and of the following claims, the term "low content of aromatic compounds" refers to a content of aromatic compounds lower than or equal to 10% by weight with respect to the total weight of said liquid hydrocarbons.

For the purposes of the present invention and of the following claims, the definitions of the numerical ranges always comprise the extremes unless otherwise specified .

According to a preferred embodiment of the present invention, said aqueous mixture can comprise a quantity of water higher than or equal to 10% by weight, pref- erably ranging from 15% by weight to 60% by weight, with respect to the total weight of said aqueous mixture .

Said alcohol can be obtained by means of fermentation processes from biomasses, i.e. from different ag- ricultural products rich in carbohydrates and sugars such as, for example, cereals, sugar cultures, starch or vinasses, or mixtures thereof, known in the art.

According to a preferred embodiment of the present invention, said alcohol can be obtained by the fermentation of at least one biomass deriving from agricultural crops, such as, for example, corn, sorghum, barley, beet, sugar cane, or mixtures thereof.

According to a further preferred embodiment of the present invention, said alcohol can be obtained by the fermentation of at least one lignocellulosic biomass. Said lignocellulosic biomass can preferably be selected from :

products of crops expressly cultivated for energy use (for example, miscanthus, common millet, foxtail millet, common cane) , including scraps , residues and waste products, of said crops or of their processing;

products of agricultural cultivations, of foresta- tion and of silviculture, comprising wood, plants, residues and scraps of agricultural processing, of forestation and of silviculture;

scraps of agro-food products intended for human nutrition or zootechnics ;

residues, not treated chemically, of the paper industry;

waste products coming from the differentiated collection of solid urban waste (e.g., urban waste of a vegetable origin, paper, etc.); or mixtures thereof.

According to a further preferred embodiment of the present invention, said aqueous mixture can derive from a fermentation broth.

According to a further preferred embodiment of the present invention, said aqueous mixture can be the ace- tone/ethanol/butanol aqueous mixture deriving from the fermentation of a biomass.

According to a preferred embodiment of the present invention, said process can be carried out in continuous, or batch ise, preferably in continuous.

Said process is preferably carried out in one or more catalytic reactors in series, with a fixed catalytic bed, or with a fluid catalytic bed, stirred or re-circulated, or containing the catalyst in dispersion, more preferably in one or more tubular fixed catalytic bed reactors.

Preferably, said catalyst can be suitably formed, it can be extruded, for example, in the form of pel- lets, suitable for use in the reactor adopted, as is well known in the state of the art and as described in greater detail hereunder.

According to a preferred embodiment of the present invention, said zeolites can be in acidic form or in at least partially acidic form.

According to a further preferred embodiment of the present invention, said catalyst can be a H-ZSM-5 zeolite.

H-ZSM-5 zeolite is a porous crystalline silico- aluminate having an MFI structure. Greater details relating to the structure of said H-ZSM-5 zeolite, as also to the processes for its preparation, are described, for example, in American patent US 3,702,886; or by Kokotailo G. T. et al . in: "Structure of synthetic zeolite ZSM-5", Nature (1978), Vol. 272, pages 437-438; by Olson D. H. et al . in: "Crystal Structure and Structure-Related Properties of ZSM-5" , in "Journal of Physical Chemistry" (1981), Vol. 85, pages 2238- 2243; by Ch. Baerlocher et al . in: "Atlas of Zeolite Framework Types" (2001) , fifth revised edition, IZA publication, Elsevier, Amsterdam, pages 185; in the Database of Zeolite Structures - Structure Commission of the International Zeolite Association (Internet ad- dress: www. iza-structure . org/databases) .

As specified above, this zeolite can be suitably formed, operating according to techniques known in the art. Said zeolite, in crystal powder form, can for example be mixed with a suitable inorganic ligand such as, for example, silica, alumina, clay (e.g., ben- tonite, kaolin), or metal oxides (e.g., zirconium oxide, magnesium oxide), or mixtures thereof. For the purposes of the present invention, alumina is the preferred ligand. Precursors of said ligand can also be mixed with the zeolite: in the case of the use of alumina, for example, one of its precursors can be used, such as, for example, bohemite or pseudobohemite, which generates alumina by calcination. Said zeolite and said ligand can be mixed in various weight ratios: the zeo- lite/ligand weight ratio can preferably range from 5/95 to 95/5, preferably can range from 15/85 to 85/15. The zeolite/ligand composite material obtained at the end of the mixing can be formed so as to obtain a zeolite having an adequate form and dimensions for use in the reactor adopted, a low pressure drop and a suitable mechanical and abrasion resistance.

Said composite material can be formed operating according to any extrusion, spherulization, pelleting, granulation process known in the art. For the purposes of the present invention, said composite material can be formed by extrusion. The extrusion generally also envisages the use of a peptizing agent which can be mixed with the zeolite and the, ligand, before extru- sion, until a homogenous paste is obtained. At the end of said extrusion, pellets having different dimensions are obtained.

For the purposes of the present invention, pellets having different forms and dimensions can be used. Pel- lets in the form of cylinders having a diameter ranging from 2 mm to 6 mm and a length ranging from 2 mm to 20 mm, are particularly suitable for the purpose.

At the end of the extrusion, the pellets obtained are generally subjected to a calcination step, for ex- ample, at a temperature of 550 °C, in a flow of air, for 10 hours.

According to a preferred embodiment of the present invention, said process can be carried out at a temperature ranging from 250°C to 400°C, preferably rang- ing from 300°C to 350°C.

According to a preferred embodiment of the present invention, said process can be carried out at a pressure ranging from 0.5 bar absolute (bara) to 10 bar ab- solute (bara) , preferably ranging from 1 bar absolute (bara) to 5 bar absolute (bara) .

According to a preferred embodiment of the present invention, said aqueous mixture including at least one alcohol can be put in contact with said catalyst at a space velocity ("weight hourly space velocity" - WHSV) , said space velocity being expressed as weight of the aqueous mixture fed per weight unit of catalyst, ranging from 0.1 h^"1 to 100 h^"1, preferably ranging from 0.5 h^"1 to 10 h^"1, more preferably from 1 h^"1 to 6 h^"1.

It should be pointed out that by operating under the conditions described above, a yield of liquid hydrocarbons is obtained, in particular C₅₊ liquid hydrocarbons, with a low content of aromatic compounds (i.e. a yield higher than or equal to 65% by weight) , said yield being calculated with respect to the total weight of the hydrocarbon component (i.e. alcohol (s) and, optionally, acetone) present in said aqueous mixtures, for a duration of said process longer than or equal to 100 hours and which, depending on the operative condi- tions adopted, can reach over 500 hours.

For the purposes of the present invention and of the following claims, the term "C₅₊ liquid hydrocarbons" refers to liquid hydrocarbons having a number of carbon atoms higher than or equal to 5. In order to recover said liquid hydrocarbons, the reaction effluents obtained by means of the process object of the present invention, can be subjected to further treatments carried out according to conventional techniques and well-known in the state of the art such as, for example, cooling, condensation and demixing between immiscible liquid phases. The liquid phase comprising said liquid hydrocarbons (i.e. condensable products) mainly comprises C₅₊ liquid hydrocarbons and is characterized, as reported above, by a low content of aromatic compounds. During said process, a gaseous phase comprising Ci- C₄ hydrocarbons (i.e. incondensable products) is also obtained, which is generally measured by means of a liters counter, analyzed, in continuous, by means of gas chromatography in order to determine the content of Ci- C₄ hydrocarbons and subsequently eliminated.

According to a further embodiment of the present invention, said liquid hydrocarbons can be subjected to hydrogenation in order to produce gasolines, kerosene, or gas oils.

Some illustrative and non- limiting examples are provided for a better understanding of the present invention and for its embodiment.

EXAMPLE 1 (invention)

The example was carried out in a micropilot plant consisting of a tubular AISI 316L stainless steel reactor having the following dimensions: height 350 mm, diameter 12.7 mm, volume 30 ml. Said reactor was equipped with an electric oven with the possibility of heating the reactor itself up to a temperature of 550°C. Upstream of the reactor, it was possible to feed both gaseous components with regulation of the flow-rate by means of a thermal mass flowmeter (TMF) , and liquid components by means of piston dosage pumps such as, for example, High Performance Liquid Chromatography (HPLC) pumps. The effective quantity of liquids fed was controlled with balance. The reaction temperature was measured in the reactor at different heights of the catalytic bed by means of a sliding thermocouple. Said plant had the possibility of operating at a pressure of up to 10 bar absolute (bara) : once the operating pressure had been established, a regulation valve main- tained the pre-fixed pressure.

Downstream of the pressure regulation valve, the reaction effluents were cooled by means of a cryostat to a temperature of -15 °C. The condensable reaction products, i.e. the C₅₊ liquid hydrocarbons and water, were condensed and collected for analysis. The incondensable products (i.e. gaseous Ci-C hydrocarbons) were measured by means of a liters counter, analyzed in continuous, every hour approximately, by means of gas- chromatographic analysis and subsequently eliminated. The process balances were obtained by collecting the liquid effluents for 1-2 hours, demixing the liquid phase comprising water from the liquid phase comprising C₅₊ liquid hydrocarbons and gas-chromatographic analysis of the two phases separated. 5 g of the commercial catalyst CBV 28014 CY 1.6 of ZEOLYST having the following characteristics, were charged into the above reactor: H-ZSM-5 zeolite; 80% zeolite, 20% alumina; silica/alumina molar ratio (SAR) equal to 280; extruded pellets. Said catalyst was ground and sieved and the fraction having a diameter ranging from 0.8 mm to 1.0 mm was recovered and introduced into the reactor. 12 g of corundum were charged beneath the layer of catalyst, whereas 9 g of corundum (particles of corundum having a diameter ranging from 0.8 mm to 1 mm) were charged above the layer of catalyst .

The pressure in the reactor was fixed at 1 bar absolute (bara) and maintained at this value by means of the pressure regulation valve present in the reactor. A flow of 10 Nl/h of nitrogen was then fed to said reactor and the temperature of said reactor was brought to 500°C. Once this temperature had been reached, after 6 hours, the nitrogen flow was interrupted and the feed- ing of 15 g/h of water was initiated in order to carry out the steaming treatment of the catalyst. Said steaming treatment was continued for 250 hours.

At the end of said treatment, the feeding of the water was interrupted, a flow of 10 Nl/h of nitrogen was sent for 10 hours and the whole mixture was then left to cool to room temperature (25°C) , again under a nitrogen flow.

After cooling, the pressure in the reactor was fixed at 4 bar absolute (bara) and maintained at this value by means of the pressure regulation valve present in said reactor. A flow of 10 Nl/h of nitrogen was then fed to the reactor and the temperature of said reactor was brought to 320 °C. After 4 hours, the reactor reached the temperature of 320°C: at this point, the feeding of the nitrogen was suspended and an aqueous mixture including n-butanol/water/acetone was fed (weight ratio: 54/44/2), at a space velocity ("weight hourly space velocity" - WHSV) equal to 5 IT¹: the feeding was continued for 214 hours.

In Table 1 is reported the yield (weight %) of the different hydrocarbon fractions present in the effluent obtained, said yield being calculated with respect to the total weight of the hydrocarbon component (i.e. bu- tanol and acetone) present in the aqueous mixtures charged, at various times (hours) .

TABLE 1

From the data reported in Table 1, it can be de- duced that by operating according to the process object of the present invention, a good yield of C₅₊ liquid hydrocarbons is obtained (average yield equal to 68.4% by weight) with a low content of aromatic compounds (aver- age content of aromatic compounds equal to 4.46% by weight with respect to the total weight of said liquid hydrocarbons) .

EXAMPLE 2 (invention)

Example 2 was carried out operating as described in Example 1, with the only difference that an aqueous mixture comprising n-butanol/isopropanol/water was fed to the reactor (weight ratio: 37/18/45) .

Table 2 reports the yield (weight %) of the different hydrocarbon fractions present in the effluent ob- tained, said yield being calculated with respect to the total weight of the hydrocarbon component (i.e. n- butanol and isopropanol) present in the aqueous mixture charged, at various times (hours) .

TABLE 2

From the data reported in Table 2, it can be deduced that by operating according to the process object of the present invention, a good yield of C₅₊ liquid hydrocarbons is obtained (average yield equal to 73.8% by weight) with a low content of aromatic compounds (average content of aromatic compounds equal to 5% by weight with respect to the total weight of said liquid hydrocarbons) .

EXAMPLE 3 (invention)

Example 3 was carried out operating as described in Example 1, with the only difference that an aqueous mixture comprising n-butanol/ water was fed to the reactor (weight ratio: 55/45) .

Table 3 reports the yield (weight %) of the different hydrocarbon fractions present in the effluent ob^¬ tained, said yield being calculated with respect to the total weight of the hydrocarbon component (i.e. n- butanol) present in the aqueous mixture charged, at various times (hours) .

TABLE 3

From the data reported in Table 3 it can be deduced that by operating according to the process object of the present invention, a good yield of C₅₊ liquid hydrocarbons is obtained (average yield equal to 75.6% by weight) with a low content of aromatic compounds (average content of aromatic compounds equal to 7% by weight with respect to the total weight of said liquid hydrocarbons) .

EXAMPLE 4 (comparative)

Example 4 was carried out operating as described in Example 3, with the only difference that 5 g of the commercial catalyst CBV 2314 CY 1,6 of ZEOLYST were charged into the reactor, having the following characteristics: H-ZSM-5 zeolite; 80% zeolite, 20% alumina; silica/alumina molar ratio (SAR) equal to 23; extruded pellets .

Table 4 reports the yield (weight %) of the different hydrocarbon fractions present in the effluent obtained, said yield being calculated with respect to the total weight of the hydrocarbon component (i.e. n- butanol) present in the aqueous mixture charged, at various times (hours) .

TABLE 4

Upon comparing the data reported in Table 3 and in

Table 4, it can be deduced that the use of a zeolite having a low silica/alumina molar ratio (i.e. SAR equal to 23) negatively influences both the yield of C₅₊ liquid hydrocarbons (average yield passes from 75.6% by weight to 47.8% by weight) and also the content of aromatic compounds (average content of aromatic compounds passes from 7% by weight to 12.2% by weight with respect to the total weight of said liquid hydrocarbons) .

Claims

A process for the production of liquid hydrocarbons with a low content of aromatic compounds, which comprises putting an aqueous mixture including at least one alcohol having from 2 to 4 carbon atoms in contact with at least one catalyst selected from zeolites having a silica/alumina molar ratio (SAR) ranging from 100 to 500.

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to claim 1, wherein said catalyst is selected from zeolites having a silica/alumina molar ratio (SAR) ranging from 200 to 300.

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to claim 1 or 2 , wherein said aqueous mixture comprises a quantity of water higher than or equal to 10% by weight with respect to the total weight of said aqueous mixture.

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to claim 3, wherein said aqueous mixture comprises a quantity of water ranging from 15% by weight to 60% by weight with respect to the total weight of said aqueous mixture .

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to any of the previous claims, wherein said alcohol is obtained by fermentation of at least one biomass deriving from agricultural cultivations such as corn, sorghum, barley, beet, sugar cane or mixtures thereof .

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to any of claims 1 to 4 , wherein said alcohol is obtained by fermentation of at least one lignocellulosic biomass.

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to claim 6, wherein said lignocellulosic biomass is selected from:

- products of crops expressly cultivated for energy use (such as miscanthus, common millet, foxtail millet, common cane) , including scraps, residues and waste of said crops or of their processing;

- products of agricultural cultivations, of fore- station and of silviculture, comprising wood, plants, residues and scraps of agricultural processing, of forestation and of silviculture;

- scraps of agro-food products destined for human nutrition or zootechnics;

- residues, not treated chemically, of the paper industry;

- waste coming from the differentiated collection of solid urban waste (such as urban waste of a vegetable origin, paper) ;

or mixtures thereof .

The process for the production of liquid hydrocar- bons with a low content of aromatic compounds according to any of claims 1 to 4 , wherein said aqueous mixture derives from a fermentation broth.

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to any of claims 1 to 4 , wherein said aqueous mixture is the acetone/ethanol/butanol aqueous mixture deriving from the fermentation of a bio- mass .

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to any of the previous claims, wherein said process is carried out in continuous, or batchwise. The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to claim 10, wherein said process is carried out in continuous.

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to any of the previous claims, wherein said process is carried out in one or more catalytic reactors in series, with a fixed catalytic bed, or with a fluid catalytic bed, stirred or recirculated, or containing the catalyst in dispersion phase.

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to claim 12, wherein said process is carried out in one or more tubular fixed catalytic bed reactors .

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to any of the previous claims, wherein said zeolites are in acidic form or in at least partially acidic form.

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to any of the previous claims, wherein said catalyst is a H-ZSM-5 zeolite.

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to any of the previous claims, wherein said process is carried out at a temperature ranging from 250°C to 400°C.

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to claim 16, wherein said process is carried out at a temperature ranging from 300°C to 350°C.

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to any of the previous claims, wherein said process is carried out at a pressure ranging from 0.5 absolute bar (bara) to 10 absolute bar (bara) . The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to claim 18, wherein said process is carried out at a pressure ranging from 1 absolute bar (bara) to 5 absolute bar (bara) .

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to any of the previous claims, wherein said aqueous mixture comprising at least one alcohol is put in contact with said catalyst at a space velocity ("weight hourly space velocity" - WHSV) ranging from 0.1 h^"1 to 100 h^"1, said space velocity being expressed as weight of the aqueous mixture fed per weight unit of catalyst.

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to claim 20, wherein said aqueous mixture comprising at least one alcohol is put in contact with said catalyst at a space velocity ("weight hourly space velocity" - WHSV) ranging from 0.5 h^"1 to 10 h^"1, said space velocity being expressed as weight of the aqueous mixture fed per weight unit of catalyst.

The process for the production of liquid hydrocarbons with a low content of aromatic compounds according to claim 21, wherein said aqueous mixture comprising at least one alcohol is put in contact with said catalyst at a space velocity ("weight hourly space velocity" - WHSV) ranging from 1 h^"1 to 6 h^"1, said space velocity being expressed as weight of the aqueous mixture fed per weight unit of catalyst.

The process for the production of liquid hydrocar- bons with a low content of aromatic compounds according to any of the previous claims, wherein said liquid hydrocarbons are subjected to hydrogenation with the aim of producing gasolines, kerosene or gas oils.