SK41795A3 - Process for isomerization of pentene-2-oic acid into pentene-3- -oic and pentene-4-oic acid by acid, basic or amphoteric catalysis - Google Patents

Abstract

The present invention relates to a process for isomerization of pentene-2-oic acid into pentene-3-oic and pentene-4-oic acids. More particularly, it relates to a process for isomerization of pentene-2-oic acid into the other pentenoic acids, caracterized in that said pentene-2-oic acid is brought in contact in vapour phase with a solid acid catalyst selected amongst the acid molecular sieves, clays, bridged clays (or pillar clays), massic oxides and acid phosphates, a solid basic catalyst selected amongst metal basic phosphates, metal basic oxides and basic molecular sieves or an amphoteric solid catalyst selected amongst metal amphoteric oxides.

Description

Technical field

The present invention relates to a process for isomerizing 2-pentenoic acid to 3-pentenoic acid and 4-pentenoic acid.

BACKGROUND OF THE INVENTION

Hydroxycarbonylation of butadiene to pentenoic acids generally leads to the formation of various positional isomers: 2-pentenoic, 3-pentenoic and 4-pentenoic acid.

3-Pentenoic acid and 4-pentenoic acid may subsequently be hydroxycarbonylated to adipic acid, while 2-pentenoic acid cannot be converted in this way.

It is therefore industrially beneficial to be able to isomerize said 2-pentenoic acid to 3-pentenoic and / or 4-pentenoic acid and thus improve the overall efficiency of the process for producing adipic acid by double hydroxycarbonylation of butadiene.

It is well known that production of this type requires considerable investment, so any increase in total yield can be expected to be extremely important.

U.S. Pat. EP-A-0 291 033 has been described by a process for the isomerization of 3-pentenoic acid or derivatives thereof, in particular its methyl ester, to 4-pentenoic acid or derivatives thereof, by passing it through a perfluorinated acidic ion exchange resin.

This procedure cannot be applied to 2-pentenoic acid and moreover, this type of resin used is not resistant to relatively high temperatures and therefore it is necessary to work in the liquid phase. As a result, a very high proportion of lactone is produced from 3-pentenoic acid, which is not desired.

U.S. Pat. EP-A-0 126 349 discloses a process for the preparation of 4-pentenoic esters by isomerization of pentenoic esters at a preferred temperature of from 100 ° C to 150 ° C in the presence of ion exchangers or acidic zeolites which contain a noble metal group 8 of the Periodic Table and distilling the resulting 4-pentenoic acid ester.

U.S. Pat. EP-A-0 266 689 discloses a similar process for the preparation of 4-pentenoic ester by isomerization of pentenoic esters in admixture with alkanol at a preferred temperature of from 100 ° C to 150 ° C in the presence of zeolites and distilling off the resulting 4-pentenoic ester .

U.S. Pat. EP-A-0 206 143 also discloses a process for preparing a 4-pentenoic ester by isomerizing pentenoic esters at a preferred temperature of from 100 ° C to 150 ° C in the presence of a pentasil type zeolite and distilling off the resulting 4-pentenoic ester.

These prior art processes only concern pentenoic acid esters and cannot be transferred to pentenoic acids alone. Moreover, all of these processes are carried out in the liquid phase.

The problem of higher recovery of 2-pentenoic acid by its isomerization to 3-pentenoic and / or 4-pentenoic acid is therefore not solved.

The present invention proposes a precise solution to this problem, which allows the conversion of 2-pentenoic acid to other pentenoic acids, which can again be hydroxycarbonylated to adipic acid.

SUMMARY OF THE INVENTION

The present invention provides a process for isomerizing 2-pentenoic acid to 3-pentenoic acid and / or 4-pentenoic acid by contacting 2-pentenoic acid in the gas phase with an acidic, basic or amphoteric solid catalyst.

In the description of the invention, the term solid acid catalyst means solid compounds, in most cases, metal oxides or metal salts formed by the dehydration of methylbutinol to the methylbutenin (methylbutinyl) test according to the reaction? ^H

H +

CH _{3 -} CH - C = CH CHCH - = C - C = CH + H-O 12

CHP The term basic solid catalyst refers to solid compounds, in most cases, metal oxides or metal salts formed by the conversion of methylbutinol into acetylene and acetone (methylbutinyl test) according to the reaction

OH

CH-C-C = CH 3 l

CHB *

HCzCH ^H 3 ^C \ w determined Ii-J

Amphoteric solid catalyst refers to solid compounds, in most cases metal oxides, which are formed by the conversion of methylbutinol to 3-hydroxy-3-methyl-2-butanone and 3-methyl-3-buten-2-one (methylbutinyl test) according to the reaction solid

OH amphoteric <ρκ ch ₃ -cc = ch-.CH-CC-CH 3 * ch ₂ - = cc-ch ₃

CH ₃ CH ₃ O CH ₃ O

For further details of this assay, reference may be made to Applied Catalysis, 78 (1991), p. 213 to 225.

The 2-pentenoic acid required in the process of the invention may be of any origin.

In most cases, as indicated above, this acid originates from the butadiene hydroxycarbonylation, but the process of the invention is not limited to the product from this source. Thus, for example, it may originate from the isomerization of 5-carbon lactones and in particular gamma-valerolactone into a mixture of pentenoic acids in the presence of acidic or basic catalysts described below.

The 2-pentenoic acid may be used either alone or may also contain different proportions of other compounds, for example other pentenoic acids, lactones, for example gamma-valerolactone, delta-valerolactone or 2-methylbutyrolactone, adipic acid, 2-methylglutaric acid or 2-ethylsuccinic acid. Generally, 2-pentenoic acid accounts for more than half the weight of such a mixture, but a lower proportion may be used if appropriate. Accordingly, the term 2-pentenoic acid also includes mixtures of this compound with one or more of the above compounds.

The acid solid catalysts include molecular sieves, acid clays, bridged clays (or reinforced clays), solid oxides and acid phosphates.

Acidic molecular sieves are particularly preferred zeolites with a pentasil structure, such as e.g. ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-48, ferrierite or mordenite structure, and those with faujasite structure, such as zeolite X or zeolite Y.

Zeolites with the structure of pentasil or mordenite are particularly preferred zeolites of type ZSM-5, ZSM-11, ZSM-22,

ZSM-23 and ZSM-48 and mordenite type having the general formula I, expressed in terms of oxides ratio

M O, X O, mSiO, pH 0/1

2 / Π '23' 2 ' ^C 2''in which

M represents an element selected from the group consisting of hydrogen, ammonium and mono-, di-, tri- and tetravalent metals,

X is a trivalent element selected from the group consisting of aluminum, gallium, iron and boron, n is a number from 1 to 4, m is a number equal to or greater than 10, p is a number from 0 to 4.

The zeolites of the faujasite structure type are with particular preference those zeolites having the general formula II, expressed in terms of the oxide ratio

M O, ZO, dSiO, xH 0/11 / in which

M is an element selected from the group consisting of hydrogen, ammonium and mono-, di-, tri- and tetravalent metals, wherein M is at least partially hydrogen,

Z is a trivalent element selected from the group consisting of aluminum, gallium, iron and boron, n is a number from 1 to 4, d is a number equal to or greater than 2, x is a number from 5 to 100.

The acidic zeolites used in the present invention are especially those zeolites. wherein the oxide of the general formula used in combination with the silica is a trivalent metal oxide.

In general, zeolites are preferred in which, in formulas I or II, M is an element selected from the group consisting of hydrogen, ammonium, alkali metals such as sodium, potassium, lithium, rubidium or cesium, alkaline earth metals such as beryllium, magnesium, calcium, strontium or barium, rare earth metals such as lanthanum or cerium, and transition metals such as iron.

A more detailed description of acid clays is given in U.S. Pat. file no. FR-A-2 622 575, incorporated herein by reference.

In the method according to the invention it is preferred to use smectites such as montmorillonites, beidellites, nontronites, hectorites, stevensity and saponites.

Bridged clays that can be used as catalysts in the process of the invention are clays in which bridges or struts have been incorporated between their scales to maintain their base distances. The base distance is the sum of the thickness of the clay scale and the distance between the scales.

The preparation of these bridged clays has been described in particular in U.S. Pat. file no. FR-A-2 543 446 and FR-A-2 618 143.

Beidellites are generally the most preferred starting clays.

The bridging of the clays can be carried out, in particular, with aluminum hydroxides, vanadium, molybdenum, zirconium, iron, niobium, tantalum, chromium, lanthanum, cerium, titanium or gallium, or by using mixed hydroxides of several of these metals.

These bridged clays may be modified, in particular by the action of dihalogen, ammonium halide or acid, such as sulfuric acid or hydrohalogenic acids. The halogen thus introduced is preferably chlorine or fluorine.

The clays, especially beidellites bridged with aluminum hydroxide, are preferably used in the process of the invention.

Solid oxides are metal oxides, metal oxide mixtures or metal oxides which have been modified, in particular by treatment with a dihalogen, an ammonium halide or an acid such as sulfuric acid or hydrohalogenic acids. The halogen thus introduced is preferably chlorine or fluorine.

Examples include, but are not limited to, mixtures of silica / alumina, silica / gallium, silica / iron oxide, and silica / boron oxide, halogenated aluminum oxides such as chlorinated or fluorinated aluminum oxides, sulfate oxide zirconium and niobium or tungsten oxides.

The acid phosphates which are useful in the process according to the invention are, for example, in particular boron phosphates, either alone or in admixture with alumina or silicon dioxide corresponding to the different boric acid / phosphoric acid molar ratios added during the synthesis, lanthanum phosphate, aluminum phosphates, corresponding to the various alumina / phosphoric acid molar ratios added during the synthesis, a mixture of phosphorus pentoxide and silica (commonly called UOP catalysts), zeolite-structured aluminophosphates (A1PO) and zeolite-structured silicoaluminophosphates (SAPO).

The basic solid catalysts which are useful in the process according to the invention are in particular basic metal phosphates, basic metal oxides, metal carbonates and basic molecular sieves.

The basic metal phosphates are, in particular, phosphates, hydrogen phosphates and dihydrogen phosphates of the general formula III (A _y POJ, (imp) / m) in which:

A represents a metal atom, a group of metal atoms or partially a hydrogen atom, y represents an integer or fraction from 3/4 to 3, depending on the valence of the elements A,

Imp means a basic impregnating compound consisting of a metal selected from the group of alkaline earth metals, alkali metals and mixtures thereof, used in combination with an opposite anion to provide electrical neutrality, the coefficient z means the weight ratio of impregnating agent to impregnated material (A ^ PO ^) and is in the range of from 0% to 20% and preferably in the range of from 2% to 10%.

The basic phosphates which are useful in the process according to the invention are preferably compounds of formula III in which (A _y POJ, (Imp) (III) in which

A is particularly preferred calcium, zirconium, lanthanum, cerium, samarium, aluminum, boron, iron and partially hydrogen, y is an integer or fraction from 3/4 to 3, depending on the valency of the elements A,

Imp consists of an alkali metal or a mixture of alkali metals and a basic anion, the coefficient z being in the range of 2% to 10%.

Examples include, but are not limited to, lanthanum phosphate used in combination with a cesium, rubidium or potassium compound, cerium phosphate used in combination with a cesium, rubidium or potassium compound, samarium phosphate used in combination with a cesium, rubidium or potassium compound. calcium phosphate used in combination with a cesium, rubidium or potassium compound, calcium hydrogen phosphate used in combination with a cesium, rubidium or potassium compound or zirconium hydrogen phosphate used in combination with a cesium, rubidium or potassium compound.

Basic phosphates of formula III can be prepared by impregnating a compound of formula IV

A 'PO (IV) wherein A' has the same meaning as A, with a solution or suspension of Imp impregnating agent in a volatile solvent, such as preferably water.

The better the Imp is more soluble and the freshly prepared Compound A '

Thus, a preferred process for preparing phosphates of formula III comprises:

a) carrying out the synthesis of compound A ' _y PO ^, then preferably without isolating compound A' _y PO ^ in the reaction mixture

b) introducing Imp impregnating agent into the reaction mixture,

c) separating the excess liquid from the solid reaction product;

(d) drying and, where appropriate, calcination.

Reference should be made to general phosphate preparation techniques (as specifically described in P. Pascal, Nouveau traité de chimie minérale, vol. X (1956), pp. 821-823 and in the Gmelins Handbuch der inorganischen Chemie, (8th ed.). 16 (C), pp. 202-206 (1956)), two major routes of access to phosphates can be distinguished. On the one hand, it is the precipitation of the dissolved metal salt (chloride, nitrate) using ammonium hydrogen phosphate and the final treatment with aqueous ammonia, optionally followed by additional neutralization, and on the other hand, the reaction of the metal oxide with phosphoric acid under heating.

The basic metal oxides used in the process of the invention are those of basic nature or those which have been alkalinized by treatment with a base such as an alkali metal hydroxide or an alkaline earth metal hydroxide.

Alkali metal oxides, alkaline earth metals, Group IIIa metals of the Periodic Table of the Elements, transition elements, or rare earth elements that are either treated with or not treated with an alkali metal hydroxide include, but are not limited to, basic metal oxides.

In particular, natural alumina treated with sodium hydroxide, zinc oxide and calcium oxide may be mentioned.

The basic molecular sieves used in the method according to the invention are in particular zeolites with a pentasil structure, such as ZSM-5, ZSM-11, ZSM-22, ZSM-23 or ZSM-48, or with a mordenite structure, a ferrieret structure or a rou faujasite, such as zeolite X or zeolite Y, of the general formula V, expressed in oxide ratio gaps

E 0, TO, bSiO, rH 0 (V) a / e 'a 3' and 'a' 'in which

E represents an alkali metal or an alkaline earth metal, either alone or with a low hydrogen content,

T is a trivalent metal selected from the group consisting of aluminum, gallium, iron and boron, and is a number from 1 to 2, b is a number equal to or greater than 2, r is a number from 0 to 100.

In the general formula (V), a low hydrogen content for the meaning of the symbol E means that the possible presence of protons in the molecular sieve may not be such that the sieve has an acidic reaction in the above test.

Of the basic molecular sieves of formula (V), sieves are preferably used where E is an alkali metal.

Non-limiting examples of basic molecular sieves include zeolites: NaZSM-5, NaMOR zeolite, 13XCs zeolite, NaY zeolite, KY zeolite, and CsY zeolite.

The amphoteric solid catalysts which can be used in the process according to the invention are in particular amphoteric metal oxides.

The amphoteric metal oxides to be used in the process of the invention are amphoteric oxides or those which have been amphoterized in the process for their preparation or subsequent preparation.

Examples of non-exhaustive amphoteric metals include, but are not limited to, toric oxide (ThO _a ), zirconium (ZrO ₌ ), titanium (Zi0 _a ), cerium (CeO _a ), silica (SiO _a ), aluminum (Al _and O) _and mixtures of several of these oxides.

The process is continuous.

The catalyst used may be arranged as a fixed bed or may be used as a fluidized bed, may be used in admixture with incompatible solids to increase the contact area.

Isomerization process is generally conducted at a temperature of from 200 DEG C. to 500 DEG C. and preferably at a temperature of from 250 C to 400 C ^e

The contact time, defined as the ratio of catalyst volume to total gas flow rate (2-pentenoic acid and carrier gas, if appropriate) at the selected temperature, usually varies from 0.1 s to 50 s in most cases from 1 s up to 10 s.

Pressure is not critical. It is usually adjusted from atmospheric pressure up to 100 bar and preferably from atmospheric pressure up to 15 bar.

The 2-pentenoic acid may be introduced into the reactor containing the catalyst itself.

It may also be present at the same time as the non-incompatible carrier gas; the simultaneous introduction can be either a mixture or a simultaneous separate introduction.

The non-incompatible carrier gas may consist of a single gas or a mixture of gases that are incompatible under reaction conditions, such as nitrogen, argon, air, steam, or carboxylic acids, which are gaseous at the temperature at which the reaction proceeds.

2-Pentenoic acid is 10% to 100% by weight. in proportion to the total weight of the gases fed to the reactor, preferably from 40% to 100% by weight.

The process according to the invention generally produces a mixture of pentenoic acids, namely 3-pentenoic and 4-pentenoic acids, both of which can be hydroxycarbonylated to adipic acid by reaction with carbon monoxide and water, as indicated above. The formation of gamma-valerolactone can also be observed.

The following examples illustrate the process of the invention.

The described embodiment is used in the examples (unless otherwise indicated).

The reactor arranged vertically (quartz glass tubes, length 15 cm and diameter 2 cm) is successively filled with 2 cm ^{3 of} quartz, homogenized with a mixture of 2 cm ^{3 of} catalyst and 10 cm ^{3 of} quartz, then 5 cm ^{3 of} quartz. The reactor packing is then terminated with glass beads (2-3 mm diameter).

The catalyst is conditioned at the temperature selected for the reaction (300 ° C, unless otherwise specified) by passing a stream of nitrogen for 2 h (2 liters / h under normal pressure and temperature conditions).

The 2-pentenoic acid is then injected using a powered syringe.

The doses of injected 2-pentenoic acid are adjusted for each example: they are expressed in ml of 2-pentenoic acid in the liquid state.

After the steady-state current has stabilized for approximately 15 minutes, the test usually takes 1 hour. The products leaving the reactor were collected in a collector with 10 ml of acetonitrile.

Analysis of the reaction products and unconverted 2-pentenoic acid is performed by gas chromatography (GC).

The following parameters are calculated in each test:

hourly mass production efficiency (HWE): the mass of the stated 2-pentenoic acid relative to the catalyst mass per hour (expressed in h ^-1 );

degree of conversion (DC) of 2-pentenoic acid; the percentage of 2-pentenoic acid converted in proportion to that indicated;

recovery (RY) of various pentenoic acids and gamma-valerolactone: mol% of each pentenoic acid or gamma-valerolactone formed relative to said 2-pentenoic acid.

DETAILED DESCRIPTION OF THE INVENTION

Examples 1 to 3

Tests of different ZSM-5 zeolites of the general formula I having different Si / Al molar ratios:

zeolite 1;

zeolite 2;

zeolite 3:

Si / Al = 30% of the elements M in formula I are hydrogen

Si / Al = 52% of the elements of formula I are hydrogen Si / Al = 120% of the elements of formula I are hydrogen.

The operating conditions are as described in the general operating methods described above.

The contact time (tc) is approximately 1.4 s in each example.

The results obtained are summarized in Table 1 below.

The abbreviations P2, P3, P4 and VAL used are as follows:

P2 = 2-pentenoic acid,

P3 = 3-pentenoic acid,

P4 = 4-pentenoic acid,

VAL = gamma-valerolactone.

Table 1

RY% HWE (h ² ) Examples catalyst DC% P4 P3 VAL Example 1 zeolite 1 34 0 26 7 4.3 Example 2 zeolite 2 55 2 30 20 3.1 Example 3 zeolite 3 33 1 25 5 4.9

Examples 4 to 11

Tests of various acid catalysts:

SiO ₂ / Al ₂ O ₃ (sold by Degussa) containing 16% by weight. aluminum oxide, zeolite Y, in which the SiO ₂ / Al ₂ O ₃ = 5a ratio is fed to the Fe ³ * cycle, lanthanum phosphate, Montmorillonite Volclay (Montmo), Montmorillonite (Volclay) bridged clay (Monto-P), chlorinated alumina, sulphated zirconium oxide, niobium oxide.

The operating conditions are the same as described above. The reaction time is 1 h, except for Example 9 with chlorinated alumina, where the reaction time is 0.5 h; the temperature may be other than 300 ° C, the nitrogen flow rate may be other than 2 L / h and the rate of introduction of 2-pentenoic acid may be other than 3.2 ml / h liquid / h.

Table 2 below shows the values of some of the parameters that vary, as well as the results obtained.

Examples 4 to 11

Assays for various acid catalysts;

SiO _a / Al _and O ₃ (sold by Degussa) containing 16% by weight. aluminum oxide, zeolite Y, in which the ratio SiO _a / Al _and O _a = 5a is fed to the Fe ³ cycle, lanthanum phosphate, Montmorillonite Volclay (Montmo), Montmorillonite (Volclay) bridged (Monto-P), chlorinated alumina, sulphated zirconia, niobium oxide.

The operating conditions are the same as described above. The reaction time is 1 h, except for Example 9 with chlorinated alumina, where the reaction time is 0.5 h; the temperature may be other than 300 ° C, the nitrogen flow rate may be other than 2 L / h and the rate of introduction of 2-pentenoic acid may be other than 3.2 ml / h liquid / h.

Table 2 below shows the values of some of the parameters that vary, as well as the results obtained.

table

ω JO 2 ¹ ABOUT * r 5.9 1.9 2.0 0.4 within and 0.4 1.9 ^ r ABOUT* ABOUT ^ r • H m ^ 4 • n and 04 • 4 04 • ABOUT M 04 rh <30 κ H < > within 04 IFL CM CM m within ABOUT* CT m C. ABOUT m about m tn and CM ABOUT • H about tt C and m <e eu rd about CM about rh CM CM m 04 For CM CC * CS m ABOUT ΤΓ CS CS tn n rh G3 r * C1 l £ about about* with · 'WITH * op <Ν. '* ε Oh * 04 m CM m CM n CM n T? within about VO CT and eM n •. 'S ^1-1 ' 3 í P o * ^ Oj '& H ^fl ' Ch of ^M 04 n CM 04 04 m about and and 04 r-- - **> CX <u (JJ e £ -i about and m about about n and about n ABOUT 04 what and CS CM and CS m and and n and CS p ch C P • <C N >> I-h (those P ABOUT k> The style of _a (S <* £ <L · the P 4 O M P - Cn · ε P 0 • * 4 p m 0 · Φ p N oe o. u tí ►C CM S e 0 f \ J s -1 ch ií B " WITH '>> C tí -. > - *? _ o o - JT ° Ό S · <CM x: CJ -> »C t> ~ a ~ c * 25 ^X G3 <UN _ r-! C d cn c - ~ ε c ^u xCL WITH" Ό they r "l 2d TH ch oh • ΗΤ Ό they (-1 jd M ch oh m Ό d r-1 jd Ή ch oh within Ό a) rh jd Ή ch oh C Ό they P CD «Ρ ch 0 « what Ό they P CD Ή ch oh ct Ό (d r ^-1 .M Ή Ch Oh about rh -a they P sd p ch 0th rh rh -a they l d jd »H ch oh

Examples 12 to 21

Tests of various basic solid catalysts: cerium phosphate with addition of 3% by weight. cesium hydrogen phosphate, calcium hydrogen phosphate (hydroxyapatite), zeolite 13XCs, aluminum oxide prepared with sodium hydroxide (10% sodium hydroxide by weight of the base), lanthanum phosphate with addition of 3% by weight. cesium hydrogen phosphate, aluminum phosphate with addition of 3% by weight. cesium hydrogen phosphate, lanthanum phosphate with addition of 3% by weight. potassium dihydrogen phosphate, magnesium oxide, zinc oxide, cerium clay.

The operating conditions are the same as those described in the general operating method described above.

The results obtained are summarized in Table 3 below, together with the parameter values that have changed in relation to the general method.

Examples 22 to 25

Tests of various amphoteric solid catalysts:

zirconia, thorium oxide, titanium dioxide, Condea clay.

The operating conditions are the same as those described in the general operating method described above.

The results obtained are summarized in Table 4 below, along with the parameter values that have changed in relation to the general operating method.

Tabuílca

ω-Ο m 10.9 2.1 within G C = «4 ABOUT m e G G TA4 2.0 ABOUT * 4 B £ m ^ 4 ^ r r4 n tad 04 m 4Γ • * 4 C ^ 4 the * rr the * 04 • 4 04 <0 > C < > ^ 4 rh TA4 and m ABOUT R4 G G G m n m and ABOUT ΤΓ Vfl m m 04 about m • tr G m C and G 04 m G ^ 4 C. * 4 about G 04 04 G G G TA4 G and cm r * i ~ * about c * n 04 G n P * CM Ό VC m r- and s e r * about 'C about ό '2 a ^c -'> let CJ = a VO ^ 4 * r CM m <o CM m TT U2 VO · r- 04 n CM m CM n • · Ι ι-1 0 4 = - = L and N M from 04 TA4 CM CM 04 04 04 CM CM T r4 · * ^ a u OJ □ E- <· ~ and Q m G m m G CM n G CM m G G m ABOUT 04 m G and m G G m G ABOUT* m G G R-1 ti O + J xd N> Jr- ⁴ <U 4J e ta o a ta CC C u ₅ O a * - d) u jj —4 -U a ~ a = <an> ^u X 0 u 3> 1 a U x f * i ~~ - i — 1 i- e ΰ U —i f ' ⁴ 0 OJ x ABOUT -. (Q ta z = \ u the J- < the and and or. o S U U d ™ and and w about and PMta t o U 0 d ™ and < w o a Γ4 ta · ta X ^Ξ * U c a - a n ta · the C = G □ Z CM <·, c ε c o x CM «όΓ —I “ U 0 (U CJ CM > 1 Ό <0 r-i ad Ή ih and CM -4 they D f-1 ad Ή U and m rh Ό r-i ad Ή h and -M and • D r-i ad * rl FCI and in ^ 4 G r r- ⁴ Ad H fc. and within -. Ό m r-i ad 'R! (4 and r-r-1> d <a r-14-r ⁴ U. a G ^ 4 Ό Ot r4 ad H h and cv R4 -c a] R-4 ad M WITH. and G CM G D R-T ad * r4 and CM Ό D r-i ad M and

table

LI-Τ ' 3. ľ 0.5 1.9 2.1 2 £ T * rh • fH cn F-T n • I-h aP > C ►o < > about CN CN m m 04 m ABOUT ABOUT ABOUT T C4 C about CN what is C C. * and and about within about r- P * - D • P and - o ~ - = - * C about n C about n C about m ABOUT and m "K- about P Ό jj > 1 r-! D P D x: 04 about P N <N ABOUT Ξ- » CM O • H ^{1 1} m ABOUT Γ4 t-J < Examples Example 22 i n CM • d D | P M ih 04 Example 24 Example 25

Industrial usability

The process of the present invention is useful on an industrial scale in the isomerization of 2-pentenoic acid (a hitherto unusable by-product) to 3-pentenoic acid and 4-pentenoic acid and optionally other products which serve as starting materials for the production of adipic acid.

Claims (28)

PATENT CLAIMS Process for isomerizing 2-pentenoic acid to 3-pentenoic acid and / or 4-pentenoic acid, characterized in that 2-pentenoic acid is contacted in the gas phase with an acidic, basic or amphoteric solid catalyst. Process according to claim 1, characterized in that the 2-pentenoic acid is used alone or containing different proportions of other compounds, such as other pentenoic acids, lactones, for example gamma-valerolactone, delta-valerolactone or 2-methylbutyrolactone; adipic acid, 2-methylglutaric acid or 2-ethylsuccinic acid. Process according to either of Claims 1 and 2, characterized in that the catalyst used is an acidic solid catalyst selected from the group of acidic molecular sieves, acid clays, bridged clays or reinforced clays, solid oxides and acid phosphates. Method according to claim 3, characterized in that zeolites of the pentasil structure such as ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-48, ferrierites, mordenites and zeolites of the faujasite structure are used as acidic molecular sieves. such as zeolite X or zeolite Y. Method according to either of Claims 3 and 4, characterized in that the acidic zeolites with a pentasil or mordenite structure are those of type ZSM-5, ZSM-11, ZSM22, ZSM-23 and ZSM-48 or of the type mordenite having Formula I, expressed as oxide ratio limits MO, XO, msio, pH 0/1 / a / n ⁹ 2 3 'i' ^p 2 '' in which M represents an element selected from the group consisting of hydrogen, ammonium and mono-, di-, tri- and tetravalent metals, X is a trivalent element selected from the group consisting of aluminum, gallium, iron and boron, n is a number from 1 to 4, m is a number equal to or greater than 10, p is a number from 0 to 4. • Method according to claim 3, characterized in that zeolites having a zeolite X or Y-type zeolite structure of zeolite having the general formula II, expressed in terms of oxide ratio limits, are used as acidic molecular sieves. M 0, ZO, dSiO, xH 0/11 / s / n 'and 3' a'a '' in which M is an element selected from the group consisting of hydrogen, ammonium and mono-, di-, tri- and tetravalent metals, wherein M is at least partially a hydrogen atom; Z is a trivalent element selected from the group consisting of aluminum, gallium, iron and boron, n is a number from 1 to 4, d is a number equal to or greater than 2, x is a number from 5 to 100. Method according to one of Claims 3 to 6, characterized in that acidic zeolites are used as acidic molecular sieves, in which the oxide used in combination with the silica is trivalent metal oxide. Method according to claim 3, characterized in that smectites such as montmorillonites, beidellites, nontronites, hectorites, stevensity and saponites are used as clays. Method according to claim 3, characterized in that as bridged clays are used clays in which bridges or reinforcements have been introduced between their scales which maintain the basic distance between the bridges by means of aluminum hydroxides, vanadium, molybdenum, zirconium, iron, niobium, tantalum, chromium, lanthanum, cerium, titanium or gallium or mixed hydroxides of several of these metals and preferably beidellites bridged with aluminum hydroxide. Process according to either of Claims 3 and 9, characterized in that bridged clays modified with dihalogens, ammonium halides or acids such as sulfuric acid or hydrohalogenic acids are used, the halogen thus introduced preferably being chlorine or fluorine. Method according to claim 3, characterized in that metal oxides, metal oxide mixtures or metal oxides which have been modified by treatment with dihalogens, an ammonium halide or an acid such as sulfuric acid or hydrogen halide are used as solid oxides, the halogen introduced thereby being preferably chlorine or fluorine. Process according to either of Claims 3 and 11, characterized in that oxides selected from mixtures of silica / alumina, silica / gallium, silica / iron oxide, oxide are used as solid oxides. silica / boron oxide, halogenated aluminum oxides, for example chlorinated aluminum oxides or fluorinated aluminum oxides, sulfated zirconium oxide, niobium oxide or tungsten oxide. Process according to claim 3, characterized in that acid phosphates selected from the group of boron phosphates, either alone or in admixture with alumina or silica, corresponding to the different boric acid / phosphoric acid molar ratios reported during the synthesis, are used. lanthanum phosphate, aluminum phosphates, corresponding to the different alumina / phosphoric acid molar ratios reported during the synthesis, phosphorus pentoxide / silica 23 mixtures, commonly referred to as UOP catalysts, alPO4 zeolite structure alumina and SAPO zeolite structure silicoaluminophosphates. Process according to either of Claims 1 and 2, characterized in that the catalyst is a basic solid catalyst selected from the group of basic metal phosphates, basic metal oxides, metal carbonates and basic molecular sieves. Process according to Claim 14, characterized in that phosphates of the general formula III (A _y POJ, (1mp) _of (III) in which: A represents a metal atom, a group of metal atoms or partially a hydrogen atom, y represents an integer or fraction from 3/4 to 3, depending on the valence of the elements A, Imp means a basic impregnating group consisting of a metal selected from the group of alkaline earth metals, alkali metals and mixtures thereof, used in combination with an anion providing electric neutrality, the coefficient z means the weight ratio of the impregnating agent to the impregnated material A ^ PO ^ and is from 0% to 20% and preferably in the range from 2% to 10%. Process according to either of Claims 14 or 15, characterized in that phosphates of the general formula III (A _y POJ, (1mp) _e (III)) are used as basic metal phosphates with particular preference in which: A is particularly preferred calcium, zirconium, lanthanum, cerium, samarium, aluminum, boron, iron and partially hydrogen, y is an integer or fraction from 3/4 to 3, depending on the valency of the elements A, Imp consists of an alkali metal or a mixture of alkali metals and a basic anion, the coefficient z being in the range of 2% to 10%. Method according to one of Claims 14 to 16, characterized in that lanthanum phosphate in combination with a cesium, rubidium or potassium compound, cerium phosphate in combination with a cesium, rubidium or potassium compound, samarium phosphate is particularly preferred as the basic metal phosphates. in combination with a cesium, rubidium or potassium compound, calcium phosphate in combination with a cesium, rubidium or potassium compound, a calcium hydrogen phosphate in combination with a cesium, rubidium or potassium compound, or a zirconium hydrogen phosphate in combination with a cesium, rubidium or potassium compound. 1S. Process according to one of Claims 14 to 17, characterized in that basic metal phosphates prepared by impregnating a compound of the formula IV are used. A ' _y PO ₄ (IV) wherein A' has the same meaning as A, with a solution or suspension of Imp impregnating agent in a volatile solvent such as preferably water. Process according to one of Claims 14 to 18, characterized in that basic metal phosphates prepared by a process comprising: a) carrying out the synthesis of compound A ' _y PO ₄ , then preferably without isolating compound A' 1 PO 4 in the reaction mixture, b) introducing the impregnating agent Imp into the reaction mixture, c) separating the excess liquid fraction from the solid reaction fraction, (d) drying and, where appropriate, calcination. Method according to claim 14, characterized in that alkali metal oxides or those which have been alkalinized with a base, such as an alkali metal or alkaline earth metal hydroxide, are particularly preferably used as basic metal oxides. Method according to one of Claims 14 to 20, characterized in that basic metal oxides selected from the group of alkali metals, alkaline earth metals, metals of group Hla of the Periodic Table of the Elements, transition metals or rare earth elements optionally impregnated with alkali hydroxide are used. metal. Method according to claim 14, characterized in that zeolites with a pentasil structure, such as ZSM-5, ZSM-11, ZSM-22, ZSM-23 or ZSM-48, with a mordenite structure, are particularly preferred as basic molecular sieves. , with a ferrierite structure or a faujasite structure, such as zeolite X or zeolite Y, of the general formula V, expressed in terms of oxides ratio E 0, TO, bSiO, rHO (V) and / or '3' and 'a ⁴ ' in which E is an alkali or alkaline earth metal, either alone or with a low hydrogen content, T is a trivalent metal selected from the group consisting of aluminum, gallium, iron and boron, and is a number from 1 to 2, b is a number equal to or greater than 2, r is a number from 0 to 100. Method according to claim 14, characterized in that ZSM-5, ZSM-11, ZSM-22, ZSM-23 and ZSM-48 zeolites, ferrierites and faujasites such as zeolite X are used as basic molecular sieves. and zeolite Y. Process according to either of Claims 1 and 2, characterized in that the catalyst used is an amphoteric catalyst selected from the group consisting of amphoteric metal oxides. Method according to claim 24, characterized in that the amphoteric metal oxides used are amphoteric oxides or oxides which have been amphoterized in their preparation process or in a subsequent operation, such as thorium, zirconium, titanium, cerium, silicon and aluminum and mixtures of several of these oxides. 26. The method of any one of claims 1 to 25, characterized in that it is carried out at temperatures of from 200 DEG C. to 500 DEG C. and preferably at temperatures of between 250 ^e C and 400 ° C. Process according to any one of claims 1 to 26, characterized in that the 2-pentenoic acid is introduced into the reactor containing the catalyst itself. Method according to any one of claims 1 to 26, characterized in that the 2-pentenoic acid is present simultaneously with the non-incompatible carrier gas, consisting of either a single gas or a mixture of gases which are incompatible under reaction conditions such as nitrogen, argon , air, steam or carboxylic acids which are in the gaseous state at the temperature at which the reaction is carried out. Process according to either of claims 27 or 28, characterized in that the 2-pentenoic acid constitutes a proportion of from 10% to 100% by weight, in proportion to the total weight of the gases to be reacted, preferably from 40% to 100%. % wt.