# US 10,369,551 B2 · Production of unsaturated carboxylic acids or acid esters with a haloapatite-based catalyst

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- Number: US 10,369,551 B2
- Document ID: US10369551B2
- Status: Granted
- Kind: B2
- Application number: 15/534,291
- Filed: 2015-12-08
- Published: 2017-11-30
- Granted: 2019-08-06
- Earliest claimed: 2014-12-10
- Assignees: Ecole Centrale De Lille; Universite De Lille; Centre National De La Recherche Scientifique
- Applicants: Ecole Centrale De Lille; Universite Des Sciences Et Technologies De Lille—Lille 1; Centre National De La Recherche Scientifique
- Inventors: Sébastien Paul; Benjamin Katryniok; Franck Dumeignil; Thomas Bonnotte
- Web page: https://patentgrep.com/patent/US10369551B2

## CPC

- B01J 27/1806: {with alkaline or alkaline earth metals}
- B01J 37/03: Precipitation; Co-precipitation
- C01B 25/455: containing halogen {(completely halogenated alkali metal phosphates C01D, e.g. lithium hexafluorophosphate C01D15/005)}
- C07C 51/377: by splitting-off hydrogen or functional groups; by hydrogenolysis of functional groups {(C07C51/36 - C07C51/373 take precedence)}
- C07C 57/04: Acrylic acid; Methacrylic acid
- B01J 27/12: Fluorides
- B01J 27/138: with alkaline earth metals, magnesium, beryllium, zinc, cadmium or mercury
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS

## Abstract

The present invention relates to the use of haloapatites as catalysts of the dehydration reaction of α-hydroxylated carboxylic acids or acid esters, in particular of lactic acid or of methyl lactate, and also to a process for producing unsaturated carboxylic acids or acid esters, in particular acrylic acid or methyl acrylate, in the gas phase in a stainless steel reactor, in the presence of such a catalyst.

## Claims

### Claim 1

Process for producing an unsaturated carboxylic acid or an unsaturated carboxylic acid ester in the presence of a catalyst, said process comprising the steps of:
dehydrating an α-hydroxylated carboxylic acid or an α-hydroxylated carboxylic acid ester, respectively, said step being carried out in the gas phase, in the presence of a solid catalyst containing at least one halogenated apatite of formula (I) below:
Ca10-x[(PO4)6−(x+y+z)(HPO4)x+z(CO3)3][Y2−(x+y+z)(CO3)y+z] (I)
in which:
Y represents at least one anion selected from the F−, Cl− anions, and the combinations of at least one F− or Cl− anion with an OH− anion;
0≤x≤1;
0≤y≤1;
0≤z≤1;
0≤x+y+z≤1,
said process being carried out in a stainless steel reactor.

### Claim 2 (depends on 1)

The process according to claim 1, wherein the dehydration step is carried out on an α-hydroxylated carboxylic acid or acid ester of formula (II) below:
in which:
R1 is an alkyl radical having from 1 to 6 carbon atoms,
R2 represents a hydrogen atom or an alkyl radical having from 1 to 6 carbon atoms;
and results in an unsaturated carboxylic acid or acid ester of formula (III) below being obtained:
in which R1 and R2 have the same meaning as in formula (II).

### Claim 3 (depends on 2)

The process according to claim 2, wherein the dehydration step is carried out on an α-hydroxylated carboxylic acid or acid ester of formula (II) in which R1 is an alkyl radical having 1 carbon atom and R2 represents a hydrogen atom, a methyl radical or an ethyl radical.

### Claim 4 (depends on 1)

The process according to claim 1, wherein the dehydration step is carried out using lactic acid and rests in acrylic acid being obtained.

### Claim 5 (depends on 1)

The process according to claim 1, wherein the catalyst contains at least one halogenated apatite of formula (I) in which Y=F−; x=0; y=0; z=0 and of Ca/P molar ratio=1.67.

### Claim 6 (depends on 1)

The process according to claim 1, wherein the dehydration reaction is carried out at a temperature greater than or equal to 300° C.

### Claim 7 (depends on 1)

The process according to claim 1, wherein the dehydration reaction is carried out at atmospheric pressure.

### Claim 8 (depends on 1)

The process according to claim 1, wherein the gas phase comprises a carrier gas and/or diluent gas.

### Claim 9 (depends on 8)

The process according to claim 8, wherein the carrier gas and/or diluent gas of the gas phase is an inert gas selected from helium and nitrogen.

### Claim 10 (depends on 1)

The process according to claim 1, wherein the halogenated apatite of formula (I) is supported by a solid support.