WO2018087031A1

WO2018087031A1 - Method for isomerising dehydration of a non-linear primary alcohol on a catalyst comprising an iron-type zeolite and an alumina binder

Info

Publication number: WO2018087031A1
Application number: PCT/EP2017/078305
Authority: WO
Inventors: Sylvie Maury; Vincent Coupard; Delphine Bazer-Bachi; Nikolai Nesterenko; Colin DUPONT; Thibault HEINZ; Laetitia ASSIE
Original assignee: IFP Energies Nouvelles; Total Research & Technology Feluy
Priority date: 2016-11-08
Filing date: 2017-11-06
Publication date: 2018-05-17
Also published as: FR3058414A1; FR3058414B1

Abstract

The invention relates to a method for isomerising dehydration of a feedstock comprising at least one primary monoalcohol, alone or in a mixture, of formula R-CH2-OH, wherein R is a non-linear alkyl radical of general formula CnH2n+1, wherein n is an integer from 3 to 20, said method operating in gas phase at a weighted mean temperature of 200°C to 275°C, at a pressure of 0.1 MPa to 1 MPa and at a WHSV (weight hourly space velocity) of 1 h-1 to 18 h-1, in the presence of a catalyst comprising at least one zeolite in H or NH4 form having at least one series of channels of which the opening is defined by a ring with 8 oxygen atoms (8MR), said zeolite being formed with at least one alumina binder, said binder lacking at least one of the elements selected independently among Si, Ti, Zr, F, Cl, Br and I. The invention likewise relates to said catalyst and a preparation method.

Description

A METHOD OF ISOMERIZING DEHYDRATION OF NON-LINEAR PRIMARY ALCOHOL ON A CATALYST COMPRISING AN IRON TYPE ZEOLITHE AND A

ALUMINUM BINDER

TECHNICAL FIELD OF THE INVENTION The present invention relates to a catalyst and its use in a process for producing alkenes from a feedstock comprising a primary monoalcohol of formula R-CH ₂ -OH, R being a nonlinear alkyl radical of general formula C _n H ₂ n ₊ i where n is an integer between 3 and 20. This charge can be obtained by chemical processes or by fermentative processes. This method uses a catalyst comprising at least one zeolite having at least one series of channels whose opening is defined by an 8-atom oxygen ring (8MR), such as ferrierite, shaped in an aluminum binder. .

Said catalyst has improved performance at low temperature, particularly in terms of selectivity to linear alkenes and in terms of conversion. The alkenes obtained, in particular isobutene, butene-1 and butenes-2, are of great interest in the field of the petrochemical industry and organic synthesis.

PRIOR ART

Recent developments have greatly improved the fermentative yields of isobutanol, making this load accessible and available at attractive cost. The conversion of isobutanol to alkene is of great interest in the field of petrochemistry. The selectivity of the dehydration reaction in the presence of a solid catalyst, and the reduction in the number of secondary products formed, remain parameters that the person skilled in the art constantly seeks to improve.

WO2004 / 078336 discloses the use of a particular gamma-alumina catalyst having specific structural properties at temperatures between 260 and 320 ° C for the dehydration of linear or branched primary alcohols. The main products obtained during the reaction at a temperature between 260 and 350 ° C, and especially between 300 and 325 ° C are di-ether and the alpha olefin corresponding to the primary alcohol dehydrated. The document WO201 1/154621 describes the use of a catalyst comprising at least 50% gamma alumina of porosity suitable for the dehydration of butanols (including isobutanol) to linear butenes and isobutene. The process operates between 250 ° C and 600 ° C and preferably 330 to 570 ° C, at a pressure between 0.1 and 1 MPa, preferably between 0.1 and 0.5MPa and with a space velocity between 0.1 and 10h ¹ . The examples describe that the dehydration of 1-butanol carried out at 380 ° C gives rise to the formation of linear butenes and isobutene as well as 10% of C5 + species. The mass ratio obtained in linear butenes / total butenes is 53 with the use of the catalyst alumina gamma.

The publication by V. Macho (Applied Catalysis A, 214, (2001), 251-257) discloses the use of gamma-alumina at temperatures between 400 and 470 ° C for the dehydration of butanols and isobutanol. At 400 ° C., the dehydration of isobutanol on non-activated gamma alumina gives a linear butene / isobutene mass ratio of 42, ie a value close to the thermodynamic equilibrium of butenes and a selectivity of 1.8% of C5 + compounds. The author recommends the use of sulfated gamma alumina which strongly favors skeletal isomerization.

WO-201 1/089235 describes the dehydration of alcohols containing from 2 to 10 carbon atoms to the corresponding olefin on a catalyst comprising a zeolite. The zeolite may be of the FER, MWW, EUO, MFS, ZSM-48, MTT, MFI, MEL or TON type with an Si / Al atomic ratio of less than 100. It may have been dealuminated or modified with phosphorus. The catalyst may contain a binder but it is explicitly stated that the binder alumina is to be avoided. The hourly space velocity (Weight Hourly Space Velocity according to the English name, WHSV) relative to the alcohol is at least 4 hours ^-1 and the temperature between 280 and 600 ° C, preferably between 320 and 600 ° C.

The document WO 201 1/1 13834 describes the simultaneous dehydration and skeletal isomerization of isobutanol in the presence of a catalyst containing a zeolite of the same type as above but having an Si / Al ratio greater than 10, or containing a silicoaluminophosphate molecular sieve. of the AEL group. The catalyst may contain a binder, but the alumina is not mentioned among the binders.

This document specifies that the dehydration catalyst may also be a silica-alumina, zirconia-alumina, titanium-alumina or fluorinated alumina mixture. These alumina catalysts must have undergone a treatment to deposit Si, Zr or Ti, this addition increases the selectivity. The WHSV with respect to the alcohol is at least 1 h ^-1 (preferably 1 to 30 h ^-1 ), the temperature of 200 to 600 ° C (preferably 300-450 ° C) and the pressure of 0.05 -1 MPa. The example relates to a catalyst consisting of ferrierite powder having an Si / Al molar ratio of 33, tested between 350 and 375 ° C. under 0.2 MPa with a space velocity of between 7 and 12 h ^-1 . the maximum proportion reached in n-butenes in butenes (linear butenes) is 58.4% at 375 ° C at high WHSV (12.6 h ^-1 ) on a powdered FER zeolite having an Si / Al ratio of 33, greater than that expected during the isomerization of isobutene at the thermodynamic equilibrium of butenes.

The document WO-2016/046296 describes the modification of powdered ferrierite by a treatment in the presence of organic acid or by an ion exchange which makes it possible to modify the ratio of strong acidic sites to weak acidic sites. The catalysts are used in the dehydration and simultaneous skeletal isomerization reactions of isobutanol. This treatment makes it possible to improve the regenerability and to limit the formation of coke on the catalysts, while maintaining good activity and selectivity. No mention of the use of any aluminum binder is made in this document.

OBJECTS OF THE INVENTION

The invention relates to a process for the isomerizing dehydration of a feedstock comprising at least one primary monoalcohol, alone or as a mixture, of formula R-CH ₂ -OH, in which R is a nonlinear alkyl radical of general formula C _n H ₂ n ₊ i where n is an integer of 3 to 20, said process operating in the gas phase at a weighted average temperature of between 200 ° C and 275 ° C, at a pressure of between 0.1 MPa and 1 MPa and at a pressure of PPH (weight per weight per hour) of between 1 and 18 h -1, in the presence of a catalyst comprising at least one zeolite in H or NH _{4 form} having at least one series of channels whose opening is defined by a ring at 8 oxygen atoms (8MR), said zeolite being shaped with at least one aluminum binder, said binder is free from at least one of the elements independently selected from Si, Ti, Zr, F, Cl, Br, and I.

The process according to the invention makes it possible to produce a mixture of alkenes rich in linear alkenes. Indeed, by the choice of operating conditions, zeolite catalyst and aluminum binder, the proportion of linear alkenes in the alkenes fraction is much higher than the value expected at thermodynamic equilibrium. Likewise, the degree of conversion of the alcohol is greater than 90%, and preferably greater than 95%. Finally, the selectivity to total alkenes is generally greater than 97% and is accompanied by a very high low amount of by-products having a higher carbon number than the starting alcohol.

Thus, at low temperature, the conversion and isomerization performances are of the same order as those obtained with a zeolite catalyst based on silica binder (silica) at a higher temperature. The temperature gain is at least 30 ° C or even 40 ° C or 50 ° C for the catalyst with the aluminum binder. This is particularly the case for a catalyst consisting of zeolite and alumina with respect to a catalyst consisting of zeolite and silica. The zeolite in question is in the list cited in this patent application; in particular it is that of type FER, and more precisely ferrierite.

The interest of the present invention is to provide an isomerizing dehydration process having good performance in terms of conversion and selectivity and operating at low temperature, i.e less than 275 ° C.

Another advantage of the method according to the invention is to have a reduced economic cost. In the sense of the present invention, the various embodiments presented can be used alone or in combination with each other, without limitation of combination.

In a preferred embodiment, n is an integer of 3 to 10.

In a preferred embodiment, the alcohol is isobutanol or 2-methyl-1-butanol, alone or as a mixture. In a preferred embodiment, the feedstock comprises isobutanol as the sole alcohol.

In a preferred embodiment, the feedstock comprises 40-100% of said alcohol.

In a preferred embodiment, the zeolite comprises at least one series of channels whose pore opening is defined by a ring containing 10 oxygen atoms (10 MR).

In a preferred embodiment, the aluminum binder content is from 10 to 50% by weight and the zeolite content from 50 to 90% by weight in the catalyst.

In a preferred embodiment, the aluminum binder consists essentially of gamma-alumina lacking one of the elements chosen from Si, Ti, Zr, F, Cl, Br, and I. In a preferred embodiment, the zeolite is of FER or MFS type.

In a preferred embodiment, the zeolite is selected from ferrierite, FU-9, ISI-6, NU-23, ZSM-35 and ZSM-57 zeolites.

In a preferred embodiment, the zeolite is ferrierite. In a preferred embodiment, the catalyst consists of at least one FER-type zeolite and gamma-alumina lacking one of the elements selected from Si, Ti, Zr, F, Cl, Br, and I .

In a preferred embodiment, the catalyst consists of said zeolite shaped with said aluminum binder. Another subject of the present invention relates to a catalyst comprising at least one zeolite in H or NH _{4 form} having at least one series of channels whose opening is defined by an 8-atom oxygen ring (8MR), said zeolite being shaped with at least one aluminum binder, said binder is devoid of at least one of Si, Ti, Zr, F, Cl, Br, and I. In a preferred embodiment, the catalyst consists of 50 to 90% by weight of at least one FER or MFS type zeolite in H or NH 4 form, said zeolite being shaped with 10 to 50% by weight of gamma alumina, said alumina is devoid of one of the elements selected from Si, Ti, Zr, F, Cl, Br, and I.

DETAILED DESCRIPTION OF THE INVENTION Charge

According to the invention, the feedstock treated in the process according to the invention comprises at least one alcohol of formula R-CH ₂ -OH, R being a non-linear alkyl group of general formula C _n H ₂ n ₊ 1 where n is an integer between 3 and 20. The charge generally comprises from 40 to 100% by weight of said alcohol. In a particular embodiment, n is an integer between 3 and 10.

The primary alcohol is preferably chosen from isobutanol or 2-methyl-1-butanol, alone or as a mixture. Very preferably, the primary alcohol is essentially isobutanol. Preferably, the feedstock comprises isobutanol as the sole alcohol. The load may contain water.

It may also comprise impurities of mineral type (such as Na, Ca, P, Al, Si, K, SO ₄ ) and of organic type (such as methanol, ethanol, n-butanol, aldehydes, ketones, and the corresponding acids, for example furanic acid, acetic acid, isobutyric acid).

The charge can come from chemical or biochemical processes, for example fermentation processes. In particular, this feedstock can be derived from fermentation processes of lignocellulosic biomass.

Process The process is carried out in the gas phase, at a weighted average temperature of between 200 and 275 ° C., at a pressure of between 0.1 MPa and 1 MPa, at a PPH of between 1 and 18 h ^-1 , in the presence of catalyst according to the invention.

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

Weighted average temperature (TMP) means the average of the 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 of 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:

Since the reaction is endothermic and the reactor operates in either isothermal or adiabatic mode, the weighted average temperature will be representative of the reaction temperature. The dehydration step is carried out in at least one dehydration reactor. The TMP of each of the reactors is adjusted to a value between 200 and 275 ° C. The reaction takes place in one or more reactors and each reactor is operated under identical conditions. Thus, in the remainder of the description, the term "the reactor" designates both the reactor of this step when it comprises only one reactor, that each of the reactors of this step, when it comprises more than one reactor. a reactor.

The dehydration reaction being endothermic, the calorie intake is achieved by any heating means known to those skilled in the art. The fact of operating at low temperature in the process according to the invention reduces the expense and avoids overheating (temperature in contact with the metal surface of the reactor or the transport lines of the load too high) which risk of result in degradation of isobutanol.

The process according to the invention which operates at low temperature is therefore economically very advantageous.

The catalyst is arranged in one or more fixed beds. They can be operated in ascending, descending or radial flow.

Catalyst

According to the invention, the catalyst used comprises a zeolite having at least one series of channels whose opening is defined by an 8-atom oxygen ring (8MR) as defined in the "Atlas of Zeolite Structure" classification. Types ", Baerlocher Ch, LB Me Cusker, DH Oison, 6th Edition, Elsevier, 2007, Elsevier." This zeolite is shaped into an aluminum binder.

According to a particular embodiment, said zeolite may also advantageously contain at least one series of channels whose pore opening is defined by a ring containing 10 oxygen atoms (10 MR), in addition to the channels whose ring 8 atoms of oxygen (8MR).

Said zeolite is advantageously chosen from zeolites of structural type FER and MFS, taken alone or as a mixture. The zeolite is more advantageously chosen in the FER type from zeolites ferrierite, FU-9, ISI-6, NU-23, ZSM-35 and for the MFS type, it is 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, it has not been treated to introduce alkaline, alkaline earth or other elements. It may nevertheless have been dealuminated. It is in H (hydrogen) or NH ₄ (ammonium) form.

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

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

The zeolite is shaped with an aluminum binder, the binder content is between 10 and 50% by weight, preferably between 20 and 40%. Preferably, the aluminum binder is composed of at least 75% alumina, preferably at least 90% and very preferably at least 95% alumina. Even more preferably, it consists essentially of alumina.

The term "essentially" means that the binder optionally contains impurities in small amounts having no technical effect on the conversion and selectivity of the catalyst. Preferably, the binder is a gamma-alumina having at least one of the elements independently selected from Si, Ti, Zr, F, Cl, Br, I.

Thus, generally, the catalyst does not include metals, or alkalis, or alkaline earths. The term "no metals, or alkalis, or alkaline earths" means that these elements are not added during the preparation, and that those present in the raw materials are in trace .

Very advantageously, the catalyst consists of at least one zeolite having at least one series of channels whose opening is 8 oxygen atoms (8MR) and an aluminum binder. Preferably, said catalyst consists of ferrierite zeolite and aluminum binder. Preferably, the aluminum binder consists essentially of alumina. The catalyst is shaped, preferably in the form of cylindrical, multilobed, bead, or powder extrudates or any other method known to those skilled in the art. Process for preparing the catalyst

The catalyst used in the process according to the invention may advantageously be prepared according to a preparation process comprising the following steps:

a) a step of mixing at least one zeolite powder with at least one powder of at least one aluminum binder and at least one solvent,

b) a step of shaping the mixture obtained at the end of step a),

c) a step of drying the shaped material obtained at the end of step b), d) a step of calcination at a temperature of between 450 and 700 ° C., of the dried material obtained at the end of step c). The process does not include any treatment step, for example with compounds containing silicon, titanium, zirconium or halogen.

The process therefore comprises the above steps to the exclusion of any other step that may have an effect on the catalytic performance.

In step a) at least one powder of at least one zeolite is mixed with at least one powder of at least one aluminum binder (or a precursor of said binder) and at least one solvent. It is possible to add during blending a blowing agent to better control the porosity.

According to the present invention, it is possible to proceed to mixtures of several powders of zeolite and / or powder of different sources of aluminas. The order in which the mixing is carried out is indifferent.

The mixture of said powders and of said solvent can advantageously be produced at one time.

Additions of powders and solvent can also advantageously be alternated.

Preferably, said powders of at least one zeolite and at least one binder are first premixed, dry, before the introduction of the solvent to facilitate obtaining a homogeneous mixture. Contacting said solvent leads to obtaining a mixture which is then advantageously kneaded. The consistency of the dough is adjusted through the amount of solvent.

Said solvent is advantageously chosen from water, ethanol, alcohols and amines, alone or as a mixture. Preferably, said solvent is water.

Advantageously, an acid is added to said solvent as a peptizing agent, preferably chosen from acetic acid, hydrochloric acid, sulfuric acid, formic acid, citric acid and nitric acid, alone or in mixed. This addition makes it possible to obtain a better dispersion of the binder and thus a better dispersion of the zeolite in this binder. In this case, an additional neutralization step subsequent to step a) can be carried out.

The neutralization is carried out by adding to the resulting mixture a base, preferably selected from ammonia, an amine, or a quaternary ammonium compound.

Preferably, at least 30% of the acidity is neutralized, and preferably at least 50%, and preferably from 95% to 99%.

Preferably, step a) of mixing is carried out by kneading, batchwise or continuously.

In batch mode, step a) is advantageously carried out in a kneader preferably equipped with Z-arms, or with cams, or in any other type of mixer such as, for example, a planetary mixer.

At the end of step a), a homogeneous mixture of the constituents is obtained.

Step b) is the shaping of the mixture obtained at the end of step a).

Preferably, the mixture obtained at the end of step a) is advantageously shaped by extrusion. Preferably, the extrusion is carried out in a piston, single-screw or twin-screw extruder.

In the case where the shaping takes place by extrusion, an organic adjuvant facilitating extrusion shaping may optionally be added in step a) of mixing. Said organic adjuvant is advantageously chosen from polyethylene glycols, mono-carboxylic aliphatics, alkylated aromatic compounds, sulphonic acid salts, fatty acids, polyvinylpyrrolidone, polyvinyl alcohol, methylcellulose, cellulose derivatives, hydroxyethylcellulose derivatives, carboxymethylcellulose, polyacrylates polymetacrylates, polyisobutene, polytetrahydrofuran, starch, polysaccharide-type polymers such as xanthan gum, scleroglucan, lignosulfonates and galactomannan derivatives, alone or as a mixture.

In the case where said method of preparation is implemented continuously and includes extrusion, the mixing step a) may be coupled with the extrusion shaping step b) in the same equipment. According to this implementation, the extrusion of the "homogeneous formulation" also called "kneaded paste" can be carried out either by extruding directly at the end of continuous twin-screw kneader for example, or by connecting one or more batch kneaders to an extruder.

In the case where the shaping of the reaction mixture resulting from step a) is carried out by extrusion, the amount of solvent used in step a) of mixing is adjusted so as to obtain under suitable conditions of pressure well known to those skilled in the art.

The geometry of the die, which confers their shape to the extrudates, can be chosen from the well-known dies of the skilled person. They can thus be, for example, cylindrical, multi-lobed or slotted, they can optionally be such that the catalyst is in the form of crushed powders, tablets, rings, balls, wheels.

Step c) is a drying of the shaped material obtained at the end of step b) at a temperature between 50 and 200 ° C and preferably between 70 and 150 ° C, preferably for a period of time between 1 and 24 hours.

Preferably, said drying step is carried out under a stream of air.

According to step d), the dried material resulting from step c) undergoes a calcination step at a temperature of between 450 and 700 ° C., preferably between 540 and 700 ° C., for a duration of between 1 and 6. h and preferably between 2 and 4h. The calcining step d) is carried out under a gaseous flow comprising oxygen, generally a gaseous flow, and most often air.

EXAMPLES

For the purposes of the present invention, the term "C5 + compound, product, or by-product" means products containing at least 5 carbon atoms.

Example 1 (according to the invention)

Catalyst A is prepared by comalaxing 70% commercial ferrierite in ammonium form having an Si / Al atomic ratio of 20, with 30% pseudo boehmite (gamma alumina precursor), and nitric acid as a peptizing agent. After 30 minutes of mixing, a neutralization step with an ammoniacal solution is carried out in order to neutralize 40% of the residual acid. After 15 minutes of mixing, the paste is extruded in cylindrical form through a die diameter 1 .9 mm, dried at 80 ° C for 12 hours and then calcined in air for 2 h at 600 ° C.

Catalyst B is prepared by comalaxing 70% commercial ferrierite in ammonium form having an Si / Al atomic ratio of 20, with 30% pseudo boehmite, and nitric acid as a peptizing agent. . After 30 minutes of mixing, a neutralization step with an ammoniacal solution is carried out in order to neutralize 99% of the residual acid. After 15 minutes of mixing, the paste is extruded in cylindrical form through a die diameter 1 .9 mm, dried at 80 ° C for 12 hours and then calcined in air for 2 hours at 600 ° C.

Example 3 (comparative)

Catalyst C is prepared by comalaxing 70% commercial ferrierite in ammonium form having an Si / Al atomic ratio of 20 and with 30% silicic binder. 2.5% TEAOH base (tetraethyl ammonium hydroxide) is added. The solid was extruded in cylindrical form with a diameter of 1 mm, dried at 80 ° C. for 12 hours and then calcined under dry air for 2 hours at 600 ° C. Example 4 (comparative)

Catalyst D is a commercial gamma alumina. This solid contains the following impurities: 0.25% weight Si, 0.02% weight P, 0.02% weight Fe, 29 ppm Na.

Example 5 (Comparative) Catalyst E is a ferrierite powder having an Si / Al atomic ratio of 22.5 previously calcined to be in proton form.

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

The dehydration step is performed 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 4 mm in a 316L stainless steel reactor with an internal diameter of 13 mm. The catalyst is then activated at 450 ° C. under 6 l / h of air for a period of one hour, after a rise in temperature of 10 ° C./min, the temperature is then lowered to the test temperature under 6 l / h. nitrogen to remove air from the system before injecting the alcohol charge. The test is carried out at atmospheric pressure. The isobutanol feed / monophasic water is vaporized in the gas phase in the heated lines at temperatures between 150 and 180 ° C upstream of the reactor and then injected into the catalytic reactor.

The analysis of the total effluent is carried out at the outlet of the reactor on an in-line gas chromatograph equipped with two columns, which makes it possible to determine the conversion of isobutanol (denoted Conversion), the selectivities in different products and in particular selectivity to butenes (denoted selectivity in C4 =) and the fraction of linear butenes in the butene section (denoted n-C4 = / C4 =), the fraction that one seeks to maximize.

The selectivity with respect to the formation of oxygenated products is also indicated and noted oxygen selectivity. The selectivity towards the products containing at least 5 carbon atoms is also measured and noted selectivity C5 +

The operating conditions as well as the performances obtained under these conditions for the catalysts A, B, C, D and E are given in the table below: The values given in the results table correspond to averages obtained over the entire duration of the test.

The PPH corresponds to the hourly weight of the injected charge relative to the weight of the catalyst.

The thermodynamic equilibrium composition of linear butenes in total butenes is 43%. Catalysts A, B, C, D, and E show total butene linear butene selectivities well above 43% under the conditions of the present invention. Catalysts A and B according to the invention have selectivities greater than the selectivities of catalysts C, D and E. The catalysts according to the present invention have conversion levels of greater than 90%. At the temperature according to the invention (250 ° C.) the catalysts A and B (in conformity) have better results than at 300 ° C. (except the invention) in terms of selectivity to butenes, selectivity to linear butenes in the total butenes and they make fewer products in C5 +.

The catalyst with a silicic binder (Catalyst C) has a low conversion at low temperature. Its performance is better at higher temperatures, such as 300 ° C which is out of the conditions of the invention. Thus, the catalysts A and B prepared with an aluminum binder according to the present invention have performances at 250 ° C higher than the catalysts C, D and E both in terms of selectivity to linear butenes in total butenes, selectivity vis-à-vis C5 + compounds in terms of conversion of alcohol.

Claims

1. Process for the isomerizing dehydration of a feedstock comprising at least one primary monoalcohol, alone or in a mixture _j . of formula Ρι-ΟΗ ₂ -ΟΗ _Α in which R is a nonlinear alkyl radical of general formula C _n H _{2n +} i where n is an integer between 3 and 20, said process operating in the gas phase at a weighted average temperature of between 200 ° C. and 275 ° C., at a pressure of between 0.1 MPa and 1 MPa and at a PPH (weight per weight per hour) of between 1 and 18 h ^-1 , in the presence of a catalyst comprising at least one zeolite in H or NH _{4 form} having at least one series of channels whose opening is defined by an 8-atom oxygen ring (8MR), said zeolite being shaped with at least one aluminum binder, said binder is devoid of at least one of the elements independently selected from Si, Ti, Zr, F, Cl, Br, I.

2. The method of claim 1 wherein n is an integer of 3 to 10.

3. A process according to any one of the preceding claims wherein the alcohol is isobutanol or 2-methyl-1-butanol, alone or in admixture.

4. Method according to one of the preceding claims wherein the feed comprises isobutanol as the sole alcohol.

5. Method according to one of the preceding claims wherein said charge comprises 40-100% of said alcohol.

6. Method according to one of the preceding claims wherein the zeolite comprises at least one series of channels whose pore opening is defined by a ring containing 10 oxygen atoms (10 MR).

7. Method according to one of the preceding claims wherein the content of aluminum binder is 10 to 50% by weight and the zeolite content of 50 to 90% by weight in the catalyst.

8. Method according to one of the preceding claims wherein the aluminum binder consists essentially of gamma alumina devoid of one of the elements selected from Si, Ti, Zr, F, Cl, Br, and I.

9. Method according to one of the preceding claims wherein the zeolite is FER or MFS type.

10. Method according to one of the preceding claims wherein the zeolite is selected from ferritic zeolites, FU-9, ISI-6, NU-23, ZSM-35 and ZSM-57.

1 1. Process according to one of the preceding claims wherein the zeolite is ferrierite.

12. Method according to one of the preceding claims wherein the catalyst consists of at least one type of zeolite FER and gamma alumina devoid of one of the elements selected from Si, Ti, Zr, F, Cl, Br, and I.

13. Method according to one of the preceding claims wherein the catalyst consists of said zeolite shaped with said aluminum binder.