Process for preparing short-chain olefins in the gas phase

Abstract

A hydroformylation process can be used for short-chain olefins, especially C2 to C5 olefins, wherein the catalyst system is heterogenized on a support that contains a porous ceramic material. Systems can also be used for carrying out said process.

Claims

1: A process for hydroformylating C2 to C8 olefins in a reaction zone using a heterogenized catalyst system, the process comprising: passing a gaseous feed mixture containing the C2 to C8 olefins together with synthesis gas over a support composed of a porous ceramic material, on which the catalyst system is in a heterogenized form; wherein the catalyst system comprises a metal from group 8 or 9 of the Periodic Table of the Elements, at least one organic phosphorus-containing ligand, a stabilizer, and optionally, an ionic liquid; wherein the support is in the form of a powder, in the form of a granular material, or in the form of pellets and wherein the support consists of a carbidic ceramic material, a nitridic ceramic material, a silicidic ceramic material, or a mixture thereof; and wherein a washcoat of the same or another ceramic material, with respect to the ceramic material of the support, is applied on the support.

2: The process according to claim 1, wherein the at least one organic phosphorus-containing ligand in the hydroformylation catalyst system has the general formula (VI):
R′-A-R″-A-R′″  (VI), wherein R′, R″, and R′″ are each organic radicals, with the proviso that R′ and R′″ are not identical, and wherein each A is a bridging —O—P(—O).sub.2— group, where two of the three oxygen atoms —O— are each bonded to the radical R′ and the radical R′″.

3: The process according to claim 1, wherein the stabilizer is an organic amine compound containing at least one 2,2,6,6-tetramethylpiperidine unit of formula (I): ##STR00010##

4: The process according to claim 1, wherein when said support consists of a nitridic ceramic material, the nitridic ceramic material is selected from the group consisting of silicon nitride, boron nitride, aluminium nitride, and mixtures thereof; wherein when said support consists of a carbidic ceramic material, the carbidic ceramic materials selected from the group consisting of silicon carbide, boron carbide, tungsten carbide, and mixtures thereof; and wherein when said support consists of a silicidic ceramic material, the silicidic ceramic material is molybdenum silicide.

5: The process according to claim 4, wherein the support consists of a carbidic ceramic material.

6: The process according to claim 5, wherein the support consists of silicon carbide.

7: The process according to claim 1, wherein the amount of the washcoat present on the support is ≤20% by weight, based on the total amount of support.

8: The process according to claim 1, wherein the support has a median particle diameter (d50) of 0.1 mm to 7 mm.

9: The process according to claim 1, wherein the hydroformylation is conducted at a temperature in the range from 65 to 200° C.

10: The process according to claim 1, wherein the hydroformylation is conducted at a pressure not greater than 35 bar.

11: The process according to claim 1, wherein the catalyst system does not comprise any ionic liquid.

12: The process according to claim 9, wherein the hydroformylation is conducted at a temperature in the range from 85 to 150° C.

13: The process according to claim 10, wherein the hydroformylation is conducted at a pressure not greater than 25 bar.

Description

EXAMPLE

Experiment 1: Preparation and Analysis of a Catalyst System According to the Invention

[0079] The starting material used for the support was a monolith of silicon carbide having a length of about 20 cm and a diameter of about 25 mm. This monolith was comminuted with a jaw crusher having a gap width of 2 mm. The comminuted support was then sieved to a target grain size of 2 to 3.15 mm and pretreated with a washcoat (SiO.sub.2). The granular material thus produced was then introduced into a round reactor sleeve of length 20 cm and having a diameter of one inch (about 2.54 cm), with glass beads of similar size introduced above and below the granular material. The granular material was then contacted with a catalyst solution containing Rh(acac)(CO).sub.2, Bisphephos (ligand), bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (stabilizer) and dichloromethane as solvent, prepared by mixing in an inert environment (glovebox). For this purpose, after the reactor had been purged with nitrogen, the catalyst solution was introduced into the reactor with a slightly positive pressure. After the solvent had been removed from the reactor by discharge and evaporation, the catalyst system heterogenized on the granular support material was used for hydroformylation.

[0080] The feed mixture used was a hydrocarbon stream having the following composition:

TABLE-US-00001 Amount (% by wt.) 1-butene/ 19.14 isobutene cis-2-butene 19.10 trans-2-butene 28.40 n-butane 30.80 isobutane 0.02 2-methylbutane 2.50

[0081] The feed mixture was guided into the reactor together with synthesis gas (molar synthesis gas:input mixture ratio=3.5:1) for hydroformylation at a gas volume flow rate of 390 m/min. The hydroformylation was conducted at a temperature of 120° C. and a pressure of 10 bar. The total conversion of butenes (i.e. the conversion of all butenes present in the feed mixture) and the n/iso selectivity (ratio of linear to branched products) was ascertained by gas chromatography via the product composition.

[0082] After an experiment duration of 380 hours, total conversion of butenes was 35% and the n/iso selectivity 97%.

Experiment 2: Preparation and Analysis of an SILP Catalyst System not According to the Invention

[0083] The catalyst system was prepared analogously to the preparation of the catalytically active composition Rh(II) in WO 2015/028284 A1.

[0084] The feed mixture used was a hydrocarbon stream having the following composition:

TABLE-US-00002 Amount (% by wt.) 1-butene/ 27.40 isobutene cis-2-butene 15.00 trans-2-butene 25.00 n-butane 29.50 isobutane 0.02 2-methylbutane 3.00

[0085] The feed mixture was guided into the reactor together with synthesis gas (molar synthesis gas:feed mixture ratio=3.5:1) for hydroformylation at a gas volume flow rate of 390 m/min. The hydroformylation was conducted at a temperature of 120° C. and a pressure of 10 bar. The total conversion of butenes (i.e. the conversion of all butenes present in the feed mixture) and the n/iso selectivity (ratio of linear to branched products) was ascertained by gas chromatography via the product composition.

[0086] After an experiment duration of 380 hours, total conversion or butenes was 25% and the n/iso selectivity 93%.

[0087] It is thus apparent from the series of experiments that the heterogenized catalyst systems according to the invention have the advantage over the known SILP systems that higher conversions and higher linearity of the products (n/iso selectivity) can be achieved therewith.