Olefin metathesis method using a catalyst containing silicon and molybdenum incorporated by means of at least two precursors

Abstract

The invention relates to a process for the metathesis of olefins implemented with a catalyst comprising a mesoporous matrix and at least the elements molybdenum and silicon, said elements being incorporated into said matrix by means of at least two precursors of which at least one precursor contains molybdenum and at least one precursor contains silicon.

Claims

1. A process comprising metathesis of olefins by bringing the olefins into contact with a catalyst comprising (i) a mesoporous matrix based on an oxide of aluminium, and (ii) at least molybdenum and silicon wherein the molybdenum and silicon are impregnated on said matrix based on an oxide of aluminium using at least two precursors of which at least one precursor contains molybdenum and at least one precursor contains silicon and is a siloxane compound of formula (Va)
[R.sub.2R.sub.3SiO].sub.n(Va) in which: R.sub.2 and R.sub.3 are hydrogen, a halide, a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl or aryl group, a substituted or unsubstituted cyclopentadienyl group or a hydroxy, alkoxy, aryloxy, siloxy, silazane, amine, diamine, amide, silyl, nitro, carboxylate, or sulphonate group, and n is an integer greater than or equal to 2, or a silsequioxane compound of formula (VI)
[RSiO.sub.3/2].sub.n(VI) in which, R is hydrogen, a halide, a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl or aryl group, a substituted or unsubstituted cyclopentadienyl group or a the hydroxy, alkoxy, aryloxy, siloxy, silazane, amine, diamine, amide, silyl, nitro, carboxylate, acetylacetonate, sulphonate, -diketiminate, iminopyrrolide, amidinate or thiocyanate group, and n is an integer greater than or equal to 2.

2. The process according to claim 1 in which the molybdenum-containing precursor is a precursor of coordination complex type based on molybdenum and/or of polyoxometallate type based on molybdenum and/or of (thio)molybdate type.

3. The process according to claim 2 in which the molybdenum-containing precursor of the coordination complex type based on molybdenum has formula (I)
Mo.sub.m(Y).sub.n(N).sub.n.(X).sub.o(CR.sub.2).sub.r(I) in which, the Y groups, identical to or different from each other, are O, S or NR, the X groups, identical to or different from each other, are a halide, chlorate, bromate, iodate, nitrate, sulphate, hydrogen sulphate, alkylsulphate, thiosulphate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, a substituted or unsubstituted alkyl, cycloalkyl or aryl group, a substituted or unsubstituted cyclopentadienyl group, or an alkoxy, aryloxy, siloxy, amide, hydrido, nitro, carboxylate, acetylacetonate, sulphonate, -diketiminate, iminopyrrolide, amidinate, borate, cyanide, cyanate, thiocyanate or NR.sub.2CS.sub.2.sup. group, the R and R groups, identical to or different from each other, are alkyl, aryl, alkoxy or aryloxy groups, m is equal to 1 or 2, n is 0 to 4, n is 0 to 2, o is 0 to 10, r is 0 to 2, and n+n+o+r is greater than or equal to 1.

4. The process according to claim 2 in which the molybdenum-containing precursor of the polyoxometallate type based on molybdenum has formula (II)
(X.sub.xMo.sub.mM.sub.bO.sub.yH.sub.h).sup.q.nH.sub.2O(II) in which, x is greater than or equal to 0, m is greater than or equal to 2, b is greater than or equal to 0, y is greater than or equal to 7, h is comprised between 0 and 12, q is 1 to 20, n is 0 to 200, x, m, b, y, h, n and q being integers, X being phosphorus, silicon or boron, and M is a metallic element that is aluminium, zinc, nickel, cobalt, tungsten, vanadium, niobium, tantalum, iron or copper.

5. The process according to claim 4 in which the precursor of the polyoxometallate type based on molybdenum is an isopolyanion based on molybdenum in which the subscript x of the element X is equal to 0.

6. The process according to claim 4 in which the precursor of the polyoxometallate type based on molybdenum is a heteropolyanion that is the Strandberg heteropolyanion of formula X.sub.2Mo.sub.5O.sub.23H.sub.h.sup.q.nH.sub.2O, the Anderson heteropolyanion of formula XMo.sub.6O.sub.24H.sub.h.sup.q.nH.sub.2O, the Keggin heteropolyanion of formula XMo.sub.12O.sub.40H.sub.h.sup.q.nH.sub.2O, a lacunary Keggin heteropolyanion of formula XMo.sub.11O.sub.39H.sub.h.sup.q.nH.sub.2O, the lacunary Keggin heteropolyanion of formula XMo.sub.9O.sub.34H.sub.h.sup.q.nH.sub.2O, the Dawson heteropolyanion of formula X.sub.2Mo.sub.18O.sub.62H.sub.h.sup.q.nH.sub.2O, or the Preyssler heteropolyanion of formula X.sub.5Mo.sub.30O.sub.110H.sub.h.sup.q.nH.sub.2O.

7. The process according to claim 4 in which the precursor of the polyoxometallate type based on molybdenum is a heteropolyanion that is the Strandberg heteropolyanion of formula X.sub.2Mo.sub.4CoO.sub.23H.sub.h.sup.q.nH.sub.2O, the Anderson heteropolyanion of formula XMo.sub.5CoO.sub.24H.sub.h.sup.q.nH.sub.2O, the Keggin heteropolyanion of formula XMo.sub.11CoO.sub.40H.sub.h.sup.q.nH.sub.2O, a lacunary Keggin heteropolyanion of formula XMo.sub.10CoO.sub.39H.sub.h.sup.q.nH.sub.2O, the lacunary Keggin heteropolyanion of formula XMo.sub.8CoO.sub.34H.sub.h.sup.q.nH.sub.2O, the Dawson heteropolyanion of formula X.sub.2Mo.sub.17CoO.sub.62H.sub.h.sup.q.nH.sub.2O, or the Preyssler heteropolyanion of formula X.sub.5Mo.sub.29CoO.sub.110H.sub.h.sup.q.nH.sub.2O.

8. The process according to claim 2 in which the molybdenum-containing precursor of the (thio)molybdate type has formula (III)
C.sub.c(MoY.sub.4).sub.z(III) in which C represents an organic or inorganic cation, the Y groups, identical to or different from each other, are O or S, c is 1 to 4, and z is 1 to 10.

9. The process according to claim 1 in which the catalyst is prepared by dry impregnation according to a process comprising: a) concomitant solubilization of the molybdenum-containing precursor and the silicon-containing precursor in a volume of solution corresponding to the pore volume of a preformed mesoporous matrix based on oxide, b) impregnation of the preformed mesoporous matrix based on oxide with the solution obtained in a), optional maturation of the solid thus obtained, c) optionally drying, calcination and/or steam treatment of solid obtained at the end of b), at a temperature of 50 C. to 1000 C., and d) thermal activation of solid obtained at the end of c), at a temperature of 100 C. to 1000 C.

10. The process according to claim 1 in which the catalyst is prepared by dry impregnation according to a process comprising: a) solubilization of the molybdenum-containing precursor in a volume of solution corresponding to the pore volume of a preformed mesoporous matrix based on oxide, b) impregnation of the preformed mesoporous matrix based on oxide with the solution obtained in a), optional maturation of the solid thus obtained, c) drying stage intended to remove impregnation solvent from solution a), d) solubilization of the silicon-containing precursor in a volume of solution corresponding to the pore volume of solid obtained in c), e) impregnation of solid obtained in c) with solution obtained in d), optionally maturation of solid thus obtained, f) optionally drying, calcination and/or steam treatment of solid obtained at the end of e), at a temperature of 50 C. to 1000 C., and g) stage of thermal activation of the solid obtained at the end of stage f), at a pressure greater than or equal to 0.1 MPa or less than or equal to 0.1 MPa, in a temperature range from 100 C. to 1000 C.

11. The process according to claim 1 in which the catalyst is prepared by impregnation in excess solution comprising: a) concomitant solubilization of the molybdenum-containing precursor and the silicon-containing precursor in a volume of solution corresponding to between 1.5 and 20 times the pore volume of the preformed mesoporous matrix based on oxide, b) impregnation of the preformed mesoporous matrix based on oxide, with solution obtained in a), filtration and recovery of solid, optional maturation of the solid thus obtained, c) optionally drying, calcination and/or steam treatment of solid obtained at the end of b) at a temperature of 50 C. to 1000 C., and d) thermal activation of solid obtained at the end of c) at a temperature of 100 C. to 1000 C.

12. The process according to claim 1 in which metathesis of olefins is carried out at a temperature of 0 to 500 C.

13. The process according to claim 12 in which the olefins are linear olefins of formula R.sup.1R.sup.2CCR.sup.3R.sup.4, where R.sup.1, R.sup.2, R.sup.3 and R.sup.4, identical or different, are hydrogen or a hydrocarbyl radical of 1 to 20 carbon atoms, or the olefins are those with a cyclic ring structure, the ring having 3 to 20 carbon atoms.

14. The process according to claim 1 in which metathesis is a cross-metathesis reaction of ethylene with 2-butene, or a reverse reaction converting propylene to a mixture of ethylene and 2-butene.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The FIGURE is a plot of catalyst productivity over time.

EXAMPLES

(2) In the examples, the molybdenum-containing precursors of the coordination complex type MoCl.sub.5, MoO.sub.2(acac).sub.2, of the isopolyanions type (NH.sub.4).sub.6Mo.sub.7O.sub.24, of the heteropolyanions type PMo.sub.12O.sub.40H.sub.3, SiMo.sub.12O.sub.40H.sub.4, the silicon-containing precursors of the silicic type Na.sub.2SiO.sub.3, of the silane type Si(CH.sub.3).sub.4 and of the siloxane type [(CH.sub.3).sub.3Si].sub.2O are commercial.

Example 1A (Not According to the Invention): Preparation of 6.7% Mo/Al.SUB.2.O.SUB.3 .by Dry Impregnation with a Solution of PMo.SUB.12.O.SUB.40..SUP.3..3H.SUP.+..30H.SUB.2.O

(3) 1.5 g of PMo.sub.12O.sub.40.sup.3.3H.sup.+.30H.sub.2O is dissolved at 60 C. in 7.3 ml of distilled water. On complete dissolution, an alumina (S.sub.BET=198 m.sup.2/g, V.sub.p=0.47 ml/g) is impregnated with this solution. The solid obtained is matured for 24 h at 25 C. under air. The resulting solid is dried in an oven at 120 C. for 24 h then activated under nitrogen at 550 C. for 2 h.

Example 1B (According to the Invention): Preparation of 6.7% Mo+1.7% Si/Al.SUB.2.O.SUB.3 .by Dry Impregnation with a Solution of PMo.SUB.12.O.SUB.40..SUP.3..3H.SUP.+..30H.SUB.2.O and Si(OEt).SUB.4.(TEOS)

(4) 1.83 g of TEOS is dissolved at 60 C. in 7.3 ml of distilled water at pH=2. On complete dissolution of TEOS, 1.5 g of PMo.sub.12O.sub.40.sup.3.3H.sup.+ is added. On complete dissolution, an alumina (S.sub.BET=198 m.sup.2/g, V.sub.p=0.47 ml/g) is impregnated with this solution. The solid obtained is matured for 24 h at 25 C. under air. The resulting solid is dried in an oven at 120 C. for 24 h then activated under nitrogen at 550 C. for 2 h.

Example 2: Metathesis of Propylene to Ethylene and 2-Butene

(5) 2 g of catalyst prepared in Example 1A and 1B is mixed in a proportion of 50% by weight with silicon carbide (SiC) in a double-jacketed fixed bed reactor. The heat transfer fluid of the double jacket is heated to 70 C. Pure propylene is conveyed to the reactor by means of a Gilson pump and the pressure is set at 4.5 MPa. The productivity of the catalysts expressed in millimole of propylene consumed per gram of catalyst and per hour is quantified as a function of time denoted t (in hours denoted h) in the FIGURE.

(6) The activity of the catalyst 1B according to the invention prepared by impregnation with a molybdenum-containing precursor and a silicon-containing precursor is greater than the activity of catalyst 1A not according to the invention and prepared by impregnation with a single molybdenum-containing precursor.

(7) The stability of catalyst 1B according to the invention is better than the stability of catalyst 1A not according to the invention.