FR3058413A1 - METHOD FOR ISOMERIZING DEHYDRATION OF A NON-LINEAR PRIMARY MONOALCOOL CHARGE ON A CATALYST COMPRISING IRON ZEOLITHE AND ALKALINE - Google Patents

Abstract

The invention relates to a process for the isomerizing dehydration of a filler comprising at least one primary monoalcohol of formula R-CH2-OH, R being a nonlinear alkyl radical of general formula CnH2n + 1 where n is an integer between 3 and 20 (preferably isobutanol) operating in the gas phase at a weighted average temperature of between 250 and 400 ° C., at a pressure of between 0.2 MPa and 1 MPa and at a PPH of between 1 and 18 h -1, in the presence of a catalyst comprising a support comprising at least one zeolite having at least one series of channels whose opening is defined by an 8-atom oxygen ring (8MR), and said zeolite having not been modified by a alkaline solution, the catalyst also containing at least one binder and at least one alkaline element selected from sodium, lithium, potassium, rubidium and cesium, the total content of alkaline element being between 0.03 and 0.70%.

Description

Holder (s): IFP ENERGIES NOUVELLES Public establishment, TOTAL RESEARCH & TECHNOLOGY FELUY.

Extension request (s)

Agent (s): IFP ENERGIES NOUVELLES.

FR 3 058 413 - A1 (54) PROCESS FOR ISOMERIZING DEHYDRATION OF A LOAD OF A NON-LINEAR PRIMARY MONOALCOHOL ON A CATALYST COMPRISING AN IRON TYPE ZEOLITH AND AN ALKALINE.

The invention relates to a process for isomerizing dehydration of a charge comprising at least one primary monoalcohol of formula R-CH2-OH, R being a non-linear alkyl radical of general formula CnH _{2tl +} i where n is an integer between 3 and 20 (preferably isobutanol) operating in the gas phase at a weighted average temperature between 250 and 400 ° C, at a pressure between 0.2 MPa and 1 MPa and at a PPH between 1 and h ' ¹ , in the presence of a catalyst comprising a support comprising at least one zeolite having at least one series of channels, the opening of which is defined by an oxygen atom ring (8MR), and said zeolite having not been modified by a alkaline solution, the catalyst also containing at least one binder and at least one alkaline element chosen from sodium, lithium, potassium, rubidium and cesium, the total content of alkaline element being between 0.03 and 0.70%.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an improved process for producing alkenes from a feedstock comprising a primary monoalcohol alone or in mixture, of formula R-CH ₂ -OH, in which R is a non-linear alkyl radical of general formula C _n H ₂ n ₊ i where n is an integer between 3 and 20 (such as isobutanol).

This charge can be obtained by chemical methods or by fermentation methods. This process uses a shaped catalyst based on a zeolite comprising at least one series of channels, the opening of which is defined by a ring with 8 oxygen atoms (8MR).

The present invention also relates to a catalyst comprising a determined content of alkaline element, and in particular of sodium and / or potassium, giving it better performance, in particular in terms of selectivity for linear butenes.

The alkenes obtained, in particular isobutene, butene-1 and butenes-2, are of great interest in the field of the petrochemical industry and of organic synthesis.

PRIOR ART

Isobutene is a key molecule in petrochemicals and for the synthesis of gasoline additives such as ΙΈΤΒΕ and MTBE. The vast majority of publications have focused on the production of isobutene from linear butanols, which are more easily produced by conventional fermentation (ABE) than isobutanol. Recent developments have however made it possible to greatly improve the fermentation yields of isobutanol, making this charge accessible and available at an attractive cost.

The document WO2009 / 074798 describes the sequence of reactions including a dehydration step on n-butanol in order to form at least 20 wt% of isobutene in the effluent. Among the zeolites effective for this reaction, ferrierite is cited, but no means of adjusting the rate of isomerism is described.

Xu et al (n-Butene Skeletal Isomerization to Isobutylene on Shape Selective Catalysts: Ferrierite / ZSM-35J. Phys. Chem., 1995, 99 (23), pp 9443-9451) indicates that the presence of sodium has a negative effect on skeletal isomerization reactions because it leads to blockage of the pores accentuated by the coking phenomena taking place during the isomerization reaction of isobutene with butenes, this resulting in almost complete deactivation of ferrierite.

The document EP 2348 005 describes the dehydration of alcohols containing from 2 to 10 carbon atoms to the corresponding olefin on a zeolitic FER catalyst with an Si / AI atomic ratio of less than 100. Weight Hourly Space Velocity according to the English name, or WHSV) with respect to alcohol is at least 4 h ¹ and the temperature from 320 to 600 ° C. Exceeding the standard of isomerization of the olefins formed is not part of the technical problem addressed by this invention. The method for preparing the solid described in the application does not describe the presence of sodium in the solid.

The document WO 2011/113834 describes the simultaneous dehydration and skeletal isomerization of isobutanol in the presence of crystalline silicate catalysts, with medium channel size (10MR) dealuminated or not, modified with phosphorus or not, from the FER group, MWW, EUO, MFS, ZSM-48, MTT, MFI, MEL or TON having a Si / AI ratio greater than 10, molecular sieves of silicoaluminophosphates from the AEL group, or silica-, zirconia-, titanium- or fluorine-alumina on zeolitic catalysts. The WHSV relative to the alcohol is at least 1 h ¹ and the temperature from 200 to 600 ° C. The madmal proportion reached in n-butenes in butenes (isobutene plus linear butenes) is 58.4% at 375 ° C at high WHSV (12.6 h ¹ ) on a FER zeolite in Si / AI 33 powder, value higher than expected during the isomerization of isobutene at the thermodynamic equilibrium of butenes. The only other catalyst exemplified is gamma alumina. On the other hand, this patent indicates that it is necessary to eliminate, by ion exchange, the alkali or alkaline-earth metals which could have been introduced during the preparation of the catalyst.

On the contrary, patent application WO-2016/046296 recommends a treatment for modification of the zeolite in particular with an alkaline solution in order to selectively poison the acid sites of the FER zeolite. The zeolite contains at least 0.5% sodium, preferably at least 1% (value exemplified), or at least 5% sodium.

The dehydration of C ₄ alcohols on acidic solids is generally accompanied by the positional isomerization of the alkene formed. These two reactions are in fact concomitant, since the position isomerization of the alkene double bond is as rapid as the dehydration reaction of C ₄ monoalcohol. In the case of isobutanol, the isobutene formed initially is easily protonated (formation of a tertiary carbocation) and can then undergo secondary reactions.

OBJECT AND INTEREST OF THE INVENTION

The invention relates to a process for converting a charge comprising a primary monoalcohol of formula R-CH2-OH into alkenes, in which R is a non-linear alkyl radical of general formula C _n H _{2n +} i where n is an integer between 3 and 20, in the presence of a catalyst comprising a binder and a zeolite having at least one series of channels, the opening of which is defined by a ring with 8 oxygen atoms (8MR) formed in a binder. The catalyst according to the invention comprises a determined quantity of alkaline element.

The process according to the invention makes it possible to produce a mixture of alkenes rich in linear alkenes. In fact, by the choice of operating conditions and of the zeolitic catalyst, a proportion of linear alkenes in the alkenes fraction is obtained which is much higher than the value expected at thermodynamic equilibrium, a substantially total conversion of the monoalcohol and a selectivity in total alkenes. greater than 97%.

DETAILED DESCRIPTION OF THE INVENTION

More specifically, the invention relates to a process for isomerizing dehydration of a charge comprising at least one primary monoalcohol of formula R-CH2-OH, R being a non-linear alkyl radical of general formula C _n H _{2n +} i where n is an integer between 3 and 20, operating in the gas phase at a weighted average temperature between 250 and 400 ° C, at a pressure between 0.2 MPa and 2 IVPa and at a PPH between 1 and 18 h ¹ , in the presence of '' a catalyst comprising at least one zeolite having at least one series of channels the opening of which is defined by a ring with 8 oxygen atoms (8MR), and said zeolite having not been modified by an alkaline solution, the catalyst also containing at least one binder and at least one alkaline element chosen from sodium, lithium, potassium, rubidium and cesium, the total content of alkaline element being between 0.03 and 0.70%.

Preferably, the alkali is sodium or potassium or even sodium and potassium.

The fact that the alkaline element is introduced not directly into the zeolite but by the binder or the peptizing agent during shaping makes it possible to ensure that the acid sites of the zeolite are not completely neutralized by the alkaline cations via an ion exchange process.

Indeed, the choice made of the duration of the kneading step during shaping as well as the small amount of solvent used in this step does not have ion exchange conditions. The alkaline cations are mainly located in the binder.

This results in an improvement in the performance of the catalyst having a specific alkali content, and which has advantageously been prepared in a particular manner.

Charge

According to the invention, the feed treated in the process according to the invention is a feed comprising at least one primary monoalcohol as defined below.

In the following description, R is a non-linear alkyl radical of general formula C _n H _{2n +} i where n is an integer between 3 and 20, preferably between 3 and 10, preferably between 3 and 7 or alternatively 3 and 5.

Preferably, the charge comprises from 40 to 100% by weight of said primary monoalcohol.

Mention may be made of the primary monoalcohols isobutanol; 3-methylbutan-1-ol; 2-methylbutan-1ol; 2,2-dimethylpropan-1-ol; 2-methylpentan-1-ol; 3-methylpentan-1-ol; 4-methylpentan-1ol; 2,2-dimethylbutan-1-ol; 2,3-dimethylbutan-1-ol; 3,3-dimethylbutan-1-ol; 2-ethylbutan-1ol. They can be alone or in a mixture.

Mention may be made of the primary monoalcohols isobutanol; 2-methylbutan-1-ol; 2,2-dimethylpropan1 -ol; 2-methylpentan-1-ol; 2,2-dimethylbutan-1-ol; 2-ethylbutan-1-ol. They can be alone or in a mixture.

Said primary monoalcohol is preferably isobutanol or 2-methyl-1-butanol, taken alone or as a mixture. Very preferably, it is essentially isobutanol, preferably the only primary monoalcohol is isobutanol.

Said filler can come from chemical or biochemical processes, for example fermentation. In particular, this charge can come from fermentation processes of biomass, in particular lignocellulosic. The load can also contain water and up to 60% water.

Said filler can also include mineral (such as Na, Ca, P, Al, Si, K, SO ₄ ) and organic impurities (such as methanol, ethanol, n-butanol, aldehydes, ketones, and the corresponding carboxylic acids, for example furanic, acetic, isobutyric acid).

Process

The process (reactor) is operated in the gas phase, at a weighted average temperature between 250 and 400 ° C, or even 250-375 ° C, at a pressure between 0.2 MPa and 2MPa, preferably between 0.2 MPa and 1 MPa, at a PPH of between 1 and 18 h ¹ , in the presence of the catalyst according to the invention. Said catalyst is arranged in one or more fixed beds, which can be operated in upward, downward or radial flow.

By PPH is meant "Weight per Weight per Hour", that is to say the mass flow rate of primary monoalcohol in the feedstock at the reactor inlet divided by the mass of catalyst in said reactor. This concept is also sometimes referred to by its English acronym WHSV, or "Weight Hourly Space Velocity".

By weighted average temperature (denoted TMP) is meant the average temperature in the catalytic bed, the bed being the set of beds present in the reactor, beds in which the catalytic reaction takes place, calculated along the axis of the flow in said bed. Let a bed of length L and surface S, the reactive mixture flowing along the longitudinal axis x of this bed, the entry into the catalytic bed forming the origin of the axis (x = 0), the weighted average temperature, denoted TMP, is expressed according to the following formula:

^L

TMP = - ^ T (x) dx E o

The reaction being endothermic and the reactor operating either in isothermal mode or in adiabatic mode, the weighted average temperature will be representative of the reaction temperature.

The reaction takes place in one or more reactors and each reactor is operated under identical conditions. The TMP of each of the reactors is adjusted to a value between 275 ° C and 400 ° C. Thus, in the following description, the term “the reactor” designates both the reactor of this stage when it comprises only one reactor, and each of the reactors of this stage, when the latter comprises more than a reactor.

Said catalyst is arranged in one or more fixed beds, which can be operated in upward, downward or radial flow.

Catalyst

According to the invention, the catalyst used comprises a zeolite having at least one series of channels, the opening of which is defined by a ring with 8 oxygen atoms (8MR) as defined in the classification “Atlas of Zeolite Structure Types, Ch. Baerlocher, LB Mc Cusker, DH Oison, 6th Edition, Elsevier, 2007, Elsevier, p142. This zeolite is shaped in a binder.

According to a particular embodiment, the zeolite can also advantageously contain at least one series of channels, the pore opening of which is defined by a ring containing 10 oxygen atoms (10 MR).

Said zeolite is advantageously chosen from zeolites having channels 8 and 10MR such as zeolites of the structural type FER and MFS, taken alone or as a mixture. The zeolite is more advantageously chosen in the FER type from the ferrierite, FU-9, ISI-6, NU-23, ZSM-35 zeolites and for the MFS type, it is the zeolite ZSM-57, taken alone or as a mixture . Said zeolite is very advantageously of the FER type and preferably it is ferrierite. Preferably, said zeolite consists of ferrierite.

Preferably, the ferrierite has an Si / Al molar ratio of 8 to 70, preferably chosen between 10 and 50.

The zeolite used was not modified by treatment with an alkaline solution. However, the zeolite may intrinsically contain up to 200 ppm by weight of alkaline element, which results from the process for preparing the zeolite, without any further treatment (dealumination, etc.).

The zeolite content in the catalyst is 50-90% by weight, preferably between 60 and 80% by weight.

The zeolite is shaped with said inert binder (for the preparation of the catalyst). Indeed, the zeolite cannot be used industrially in the form of powder, because gives rise to a pressure drop in the reactors in too high a fixed bed.

The binder is a silicic binder, an AIPO4, a clay, a zirconia, a Ti oxide. preferably it is a silicic binder. Generally the silica binder is based on silica, in particular amorphous silica.

The content of binder in the catalyst is between 10 and 50% by weight, preferably between 20 and 40%. It optionally contains impurities in small quantities having no technical effect on the conversion / selectivity of the catalyst.

Very advantageously, the catalyst consists of at least one zeolite having at least one series of channels, the opening of which is 8 oxygen atoms (8MR) and a binder, in particular a silica binder. Preferably, said catalyst consists of ferrierite zeolite and silica binder. Preferably, the silicic binder consists of silica (apart from impurities, these having no catalytic effect).

Said catalyst is shaped (extruded). The alkaline element (s) are preferably added during the mixing between the zeolite and the binder. Preferably, they are provided by the binder and / or by one or more salts dissolved in the solvent (most often water) and / or by the peptizing agent. The alkaline element (s) can also be introduced after the calcination step, since an additional heat treatment step is carried out.

The catalyst according to the invention contains at least one of the above-mentioned alkaline elements (sodium, lithium, potassium, rubidium and cesium) and preferably sodium and / or potassium. The total content of alkaline element is from 0.03% to 0.7% wt, even more preferably from 0.04% to 0.7%, preferably from 0.03 to 0.6% or from 0.04% to 0.6%. Very advantageously, the content is 0.03 % to 0.45% or 0.04 to 0.45%. Preferably, the content is from 0.2% to 0.7% or 0.6% or 0.45%. The% is expressed relative to the final calcined solid.

The catalyst object of the invention is the new catalyst (or fresh catalyst) loaded into the reactor. The new catalyst is a catalyst which has never been used in the process according to the invention.

Preparation process

Said catalyst used in the process according to the invention is advantageously prepared according to a preparation process comprising at least the following steps:

1) a step of mixing at least one zeolite powder, preferably in protonic or ammonium form, with at least one binder, preferably a silicic binder, for example an amorphous silica powder;

2) a kneading step in the presence of the addition of solvent, advantageously water, and optionally a peptizing agent; preferably a peptizing agent is used; the duration of the kneading is less than 1 hour and the total amount of solvent (including the solvent of the peptizing agent) is such that the PAF (loss on ignition) is between 28 and 40% by weight, preferably between 28- 30% wt, preferably 30 to 35%;

3) a step of shaping the pasty mixture obtained at the end of step 2), for example by extrusion using a die of suitable geometry;

4) at least one heat treatment step between 50 and 800 ° C of the shaped material obtained at the end of step 3), comprising drying carried out at a temperature between 50 and 200 ° C, preferably between 80 and 150 ° C., advantageously for a period of between 1 and 24 h, and calcination, and advantageously in air.

The preparation process includes a step of introducing an alkaline element (preferably Na and / or K) which takes place

a) -in step 1) of mixing the zeolite with the binder and / or

b) -in step 2) with the addition of solvent alone or in combination with the peptizing agent and / or

c) -after step 4) of calcination, the process then comprising an additional heat treatment step.

The mixing time is preferably less than 30 minutes, and advantageously between 10 and 20 minutes.

The PAF of the solvent + dry powders mixture is 28-40% by weight. The mass of dry powders is determined during a heat treatment at 550 ° C for 2 hours, in air and at atmospheric pressure.

The binder can also contain one or more alkaline elements (preferably Na and / or K).

The binder (and in particular the silicic binder) used in step 1 is well known to those skilled in the art, it is chosen for its inert nature with regard to the operating conditions and with regard in particular to the presence of water in the process.

Advantageously, one can use a binder containing at least one alkaline element, such as sodium or potassium. It is possible to use a binder not containing said alkaline element (such as sodium and / or potassium), said element (Na and / or K) being then introduced subsequently. It is also possible to use a mixture of binder containing an alkaline element with a binder not containing it or comprising a different content.

A source of silicic binder can be a precipitated silica or a silica obtained from byproducts such as fly ash, for example silico-aluminous or silico-calcium particles, and silica fumes. It is advantageous to use a colloidal silica, for example in the form of a stabilized suspension. An amorphous silica powder can advantageously be used in step 1).

The zeolite powder and the binder (such as silicic), preferably in the form of a powder, are advantageously kneaded in the presence of a solvent (step 2), preferably water in which a peptizing agent can advantageously be dissolved in order to to obtain a better dispersion of the binder. The consistency of the dough is adjusted through the amount of solvent.

The peptizing agent used during this step can advantageously be an acid, an organic or inorganic base such as acetic acid, hydrochloric acid, sulfuric acid, formic acid, citric acid and acid. nitric, alone or as a mixture, ammonia, an amine, a compound with quaternary ammonium, chosen from alkyl ethanol amines or ethoxylated alkyl amines, tetraethylammonium hydroxide and tetramethylammonium.

The peptizing agent can advantageously be chosen from mineral bases such as soda or potash in order to allow the addition of alkaline element, in particular Na or K.

The solvent of step 2) is advantageously water. One can also also incorporate the alkaline element (s) by means of dissolved salts of the solvent.

The binder can advantageously be a mixture of binders, one or more of which contain one or more alkaline elements (group IA).

During step 3 of shaping, the kneaded dough is extruded through a die whose geometry will impose the shape of the catalyst.

The sodium and potassium content is measured by plasma torch atomic emission spectrometry after mineralization of the catalyst by attack with an HCl / HF mixture, then dissolving in dissolved hydrochloric acid.

EXAMPLES

Example 1 (according to the invention)

Catalyst A is prepared by mixing 70% of commercial ferrierite powder in ammonium form having an Si / AI atomic ratio of 20 containing 100 ppm of Na and 21% of a source of silica containing 703 ppm of Na, and 9% of '' a source of silica containing 1340 ppm of Na. The mass fractions are calculated relative to the total dry mass of the powders. An aqueous solution of triethylammonium, TEAOH, (2.5% by mass relative to the dry mass of the powders) is then added in order to obtain a paste by kneading. The solid was extruded, dried and then calcined.

Example 2 (with added sodium hydroxide) according to the invention

Catalyst B is prepared by mixing 70% of commercial ferrierite powder in ammonium form having an Si / AI atomic ratio of 20 containing 100 ppm of Na and 30% of silica binder containing 703 ppm of Na, The fractions are calculated relative to the total dry mass of the powders. An aqueous sodium hydroxide solution, NaOH, (0.5% by mass relative to the dry mass of the powders) is then added in order to obtain a paste by kneading. The solid was extruded, dried and then calcined.

Example 3 (addition of potash) according to the invention

Catalyst C is prepared by mixing 70% of commercial ferrierite powder in ammonium form having an Si / Al atomic ratio of 20 containing 100 ppm of Na and 30% of silica binder containing 703 ppm of Na. The fractions are calculated relative to the total dry mass of the powders. An aqueous KOH potassium solution (0.5% by mass relative to the dry mass of the powders) is then added in order to obtain a paste by kneading. The solid was extruded, dried and then calcined.

Example 4 (according to the invention)

Catalyst D is prepared by mixing 70% of commercial ferrierite powder in ammonium form having an Si / Al atomic ratio of 20 containing 100 ppm of Na and 30% of silica binder containing 703 ppm of Na. The fractions are calculated relative to the total dry mass of the powders. An aqueous sodium hydroxide solution, NaOH, (1% by mass relative to the dry mass of the powders is then added in order to obtain a paste by kneading. The solid was extruded, dried and then calcined.

Example 5 (comparative) (too much K, 2% and Na provided by the two sources of silica)

Catalyst E is prepared by mixing 70% of commercial ferrierite powder in ammonium form having an Si / AI atomic ratio of 20, containing 100 ppm of Na and of 21% of silicic binder containing 709 ppm of Na and of 9% of silicic binder containing 1340ppm of Na. The fractions are calculated relative to the total dry mass of the powders. An aqueous solution of potassium hydroxide, KOH, (2% by mass relative to the dry mass of the powders) is then added in order to obtain a paste by kneading. The solid was extruded, dried and then calcined.

Example 6 (comparative)

Catalyst F is prepared by co-mixing 70% of commercial ferrierite powder in ammonium form having an Si / AI atomic ratio of 20 containing 100 ppm of Na and 30% of silica binder containing 703 ppm of Na. The fractions are calculated relative to the total dry mass of the powders. An aqueous solution of triethylammonium, TEAOH, (2.5% by mass relative to the dry mass of the powders) is then added in order to obtain a paste by kneading. The solid was extruded, dried and then calcined.

Catalytic test used to evaluate the performance of the catalysts of the examples.

The dehydration step is carried out on a catalytic test unit comprising a fixed bed operating in “down flow” mode, that is to say in downflow mode. The catalyst is loaded in the form of extrudates of length 2 to 4mm into a 316L stainless steel reactor with an internal diameter of 13mm. The catalyst is then activated at 450 ° C. under 6 l / h of air for a one hour plateau, after a temperature rise of 10 ° C. / min, the temperature is then lowered to the test temperature under 6 l / h nitrogen to eliminate the air present in the system before injection of the alcohol charge.

The charge is an isobutanol / monophasic water mixture. It is vaporized in the lines heated to 150-180 ° C upstream of the reactor and then injected into the catalytic reactor. The operating conditions are as follows: pressure 2 bar (0.2 MPa), fixed temperature of 300 ° C, WHSV (weight per load weight catalyseurpar gram) of 7h ¹ for 24 h, then 20h ¹ for 48 h, then again at pph 7h ¹ for 24h (return point).

The analysis of the total effluent is carried out at the reactor outlet on an in-line gas chromatograph equipped with two columns, which makes it possible to determine the conversion of isobutanol, the selectivities to different products and in particular the fraction of butenes linear in the butene section, fraction which one seeks to maximize, and the selectivity in oxygenated by-products, parasitic reactions which one wishes to minimize. The measurement of the average conversion achieved during the 24 hours of the return point is compared to the average conversion achieved during the first 24 hours at pph 7h ¹ and makes it possible to evaluate the loss of activity during the test.

Catalyst Conversion on point return (%) n-butenes sum butenes (%) at the return point Selectivity in oxygenated (%) at the return point Content Na (% wt) K content (°: _o wt) A (compliant) 99.7 83.6 0.04 0.030 0 B (compliant) 97.6 84.0 0.11 0.320 0 C (compliant) 96.6 83.2 0.09 0.030 0.35 D (compliant) 95.8 85.0 0.09 0.600 0 E (non-compliant) 75.0 81.9 0.20 0.030 1.39 F (non-compliant) 98.1 81.2 0.10 0.020 0

Catalysts A-D containing a K or Na or K + Na content greater than 0.030 and less than or equal to 0.600% have a substantially increased fraction of n-butenes in total butenes.

Claims (5)

1. A method of isomerizing dehydration of a charge comprising at least one primary monoalcohol of formula R-CH2-OH, R being a non-linear alkyl radical of general formula C _n H _2n + i where n is an integer between 3 and 20 , operating in the gas phase at a weighted average temperature between 250 and 400 ° C, at a pressure between 0.2 MPa and 2 MPa and at a PPH (mass flow rate of primary monoalcohol in the feedstock at the reactor inlet divided by the mass of catalyst in said reactor) between 1 and 18 h ¹ , in the presence of a catalyst comprising a support comprising at least one zeolite having at least one series of channels whose opening is defined by a ring with 8 atoms of oxygen (8MR), and said zeolite not having been modified by an alkaline solution, the catalyst also containing at least one binder and at least one alkaline element chosen from sodium, lithium, potassium, rubidium and cesium, the total content of alkaline element being between 0.03 and 0.70%. 2. Method according to claim 1 wherein the alkaline elements are Na and / or K. 3. Method according to one of the preceding claims, in which the zeolite is of the FER or MFS structural type, and is preferably chosen from the group formed by ferrierite, FU-9, ISI-6, NU-23, ZSM-35, ZSM-57. 4. Method according to one of the preceding claims wherein the zeolite is a ferrierite. 5. Method according to one of the preceding claims, in which the zeolite is a ferrierite having an Si / Al molar ratio of 8 to 70, and preferably 10 to 50. 6. Method according to one of the preceding claims in which the binder is chosen from the group formed by a silica binder, an AIPO4, a clay, a zirconia, a titanium oxide, and preferably a silica binder. 7. Method according to one of the preceding claims, in which the zeolite content is 50-90% by weight and preferably 60-80%. 8. Method according to one of the preceding claims wherein the support consists of the zeolite and the binder. 9. Method according to one of the preceding claims wherein said monoalcohol is isobutanol. 10. Method according to one of the preceding claims wherein said monoalcohol is 2-methyl-1 -butanol. 11. Method according to one of the preceding claims, in which the alkali content is from 0.03% to 0.7%, preferably from 0.03 to 0.6% or from 0.04% to 0.6%. 12. Method according to one of the preceding claims, in which the alkali content is from 0.03% to 0.45% or from 0.04 to 0.45%. 13. Catalyst comprising a support comprising at least one zeolite having at least one series of channels, the opening of which is defined by a ring with 8 oxygen atoms (8MR), and said zeolite having not been modified by an alkaline solution , the catalyst also containing at least one binder and at least one alkaline element chosen from sodium, lithium, potassium, rubidium and cesium, the total content of alkaline element being between 0.03 and 0.70%. 14. Process for the preparation of the catalyst according to claim 11, comprising at least the following steps: 1) a step of mixing at least one zeolite powder in protonic or ammonium form with at least one binder, 2) a kneading step in the presence of adding solvent, and optionally a peptizing agent, the kneading time is less than 1 hour and the total amount of solvent is such that the PAF (determined during a heat treatment at 550 ° C for 2 hours, in air and at atmospheric pressure) is between 28 and 40% w / w, 3) a step of shaping the pasty mixture obtained at the end of step 2), 4) at least one heat treatment step between 50 and 800 ° C. of the shaped material obtained at the end of step 3), comprising drying and calcination, and advantageously in air. said preparation process comprising a step of introducing an alkaline element, preferably Na and / or K, which takes place a) - during step 1) of mixing the zeolite with the binder and / or b) - during step 2) with the addition of solvent alone or in combination with the peptizing agent and / or c) - after step 4) of calcination, the process then comprising an additional heat treatment step. 15. The method according to claim 14, in which the binder is a silica binder, the solvent is water, and the drying step is carried out at a temperature between 50 and 200 ° C, preferably between 80 and 150 ° C, advantageously for a period of between 1 and 24 h, and advantageously in air.