GB2072217A

GB2072217A - Process for the hydrogenation of hydrocarbons having non- terminal olefinic double bonds

Info

Publication number: GB2072217A
Application number: GB8108346A
Authority: GB
Original assignee: Erdoelchemie GmbH
Current assignee: Erdoelchemie GmbH
Priority date: 1980-03-20
Filing date: 1981-03-17
Publication date: 1981-09-30
Also published as: FR2478624A1; DE3010720C2; FR2478624B1; GB2072217B; JPS56145229A; DE3010720A1

Abstract

Hydrocarbons having olefinic double bonds of which at least one is not in the end position are hydrogenated with excess hydrogen using a nickel catalyst on kieselguhr at an elevated temperature and under elevated pressure. The nickel content of this catalyst is 50 to 70% by weight, based on the total weight of the catalyst. The kiesselguhr has a specific surface area of 100 to 180 m<2>/g and contains, in addition to 85 to 93% by weight of SiO2, a further 3 to 8% by weight of Al2O3, 0.1 to 0.2% by weight of TiO2, 1 to 1,6% by weight of Fe-oxides, 0.1 to 0.7% by weight of MgO, 0.3 to 1% by weight of CaO and 0.7 to 1.5% by weight of alkali metal oxides, all based on the total weight of the kieselguhr. The LHSV is set at 0.1 to 8 litre of substrate per litre of reaction volume per hour.

Description

SPECIFICATION Process for the hydrogenation of hydrocarbons with non-terminal olefinic double bonds The present invention relates to a process for the hydrogenation of hydrocarbons with olefinic double bonds, of which at least one is non-terminal, with hydrogen on a nickel-on-kieselguhr supported catalyst.

It is known that diisobutene, triisobutylene or tetraisobutene can be hydrogenated on a palladium catalyst on sintered aluminium oxide or on spinel under a hydrogen pressure of 25 to 30 atmospheres and at a temperature of 1 80 to 2200C (DE-AS (German Published Specification) 1,275,525 and DE-AS (German Published Specification) 1,518,817). These catalysts have the disadvantages of a relatively short life, of high costs, as a result of the noble metal content, and of the need to remove them from the reactor before regeneration.

Nickel catalysts on SiO2 or Awl203 as the support likewise have only short lives, and cannot achieve the desired degree of hydrogenation, expressed by the bromine number of the end product.

A process has been found for the hydrogenation of hydrocarbons with olefinic double bonds, of which at least one is non-terminal, with excess hydrogen on metal catalysts on supports, at elevated temperature and under increased pressure, which is characterised in that a supported nickel catalyst which has a nickel content of 50 to 70% by weight preferably 5565% by weight, relative to the total weight of the catalyst, and of which the support is kieselguhr which has a specific surface area of 100 to 180 m2/g and also contains, in addition to 85 to 93% by weight of Six2,3 to 8% by weight of Awl203, 0.1 to 0.2% by weight of Tit2,1 to 1.6% by weight of Fe oxides, 0.1 to 0.7% by weight of MgO, 0.3 to 1% by weight of CaO and 0.7 to 1.5% by weight of alkali metal oxides, all relative to the weight of the kieselguhr, is used, and in that an hourly space velocity of 0.1 to 8 litres substrate per litre of reaction space per hour is maintained.

Feed products which may be mentioned for the process according to the invention are hydrocarbons which have olefinic double bonds, of which at least one is non-terminal, and which can be described by the generai formula

in which R1, R2, R3 and R4 independently of one another denote C1-C22-alkyl or C1-C22-alkenyl, R1 and R2 together containing at least 4 C atoms, and R3 and R4 independently of one another can additionaliy represent hydrogen.

Such oleiinically unsaturated hydrocarbons can be obtained, for example, in the oligomerisation of propylene and of the various isomeric butenes in the presence of acid catalysts, such as H3PO4 on active charcoal or macroporous acid cation exchangers, and lead to olefinic oligomers with, for example, 6 to 24 C atoms in the molecule. These olefines, such as isohexenes, diisobutene, di-n-butene, co-dimers of isobutene and n-butene, and nonene and isonenes, tetrapropene, pentapropene and tri-, tetra- and penta-co-oligomers of iso- and n-butenes, as well as still higher oligomers of propene and butenes, can be used as such for further chemical reactions.However, other industrial applications require a conversion of the olefinic oligomers into the corresponding paraffin hydrocarbons, which are used, for example, as highly pure solvents for polymerisation reactions, for plastisols, paints and cleaning agents for domestic use and for protecting vehicles, as well as for insecticidal solutions, aerosols, cosmetic preparations and as extractants for fats.

The isolated double bonds which occur in the oligomers described and are not terminal are difficult to hydrogenate and generally can be only incompletely hydrogenated. This difficulty is intensified further in the case of olefinically unsaturated hydrocarbons with relatively high molecular weights. Straight-chain and branched, olefinically unsaturated hydrocarbons which have a non-terminal double bond and have at least 10 C atoms in the molecule are thus preferred as the feed product for the process according to the invention.

The process according to the invention is carried out on a supported nickel catalyst which is characterised both by its nickel content and by the specific surface area and the particular composition of its-kieselguhr support. A nickel content of 50 to 70, preferably 55 to 65, % by weight, relative to the total weight of the catalyst, may be mentioned by way of example. A specific surface area of the kieselguhr used of 100 to 180, preferably 120 to 170, m2/g may be mentioned. The particular material composition of the kieselguhr used as the support is characterised by a content of titanium dioxide.A material composition which may be mentioned is, in addition to a content of 85 to 93% by weight of Six2, a content of 3 to 8% by weight of Al203, 0.1 to 0.2% by weight of Tit2,1 to 1.6% by weight of Fe oxides, 0.1 to 0.7% by weight of Mug0, 0.3 to 1% by weight of CaO and 0.7 to 1.5% by weight of alkali metal oxides, all relative to the weight of the kieselguhr. Furthermore, the distribution of the pore radii of the kieselguhr used as the catalyst support is: 20 to 40% less than 50 A, 30 to 50% between 50 and 100 A, 4 to 20% between 100 and 200 A and 1 to 6% between 200 and 300 A.

Kieselguhr which has a content of titanium dioxide and is suitable for the process according to the invention is found, for example, in Luneburg Heath (Rmpp, Chemie-Lexikon (Chemical Dictionary), 7th edition, Volume 3, page 1,770, Franckh'sche Verlagshandlung Stuttgart). As a result of the aftertreatment of the kieselguhr extracted, by drying and heating in a rotary kiln, during which organic material is burned and volatile constituents escape, the chemical composition of the kieselguhr can vary greatly and be changed. For the process according to the invention, the composition should remain within the ranges mentioned.

The nickel-on-kieselguhr supported catalyst used according to the invention is prepared in a known manner, for example by impregnating the kieselguhr described above with a liquid containing a nickel compound and then drying and, if appropriate, heating the impregnated kieselguhr and reducing the nickel compound to active elementate nickel, for example with hydrogen.

The process, according to the invention, for complete hydrogenation of olefinically unsaturated hydrocarbons can be carried out in the liquid, in the trickle phase or in the gas phase, in a fixed bed reactor, fiuidised bed reactor or tube reactor, the catalyst remaining stationary in the reactor. The feed product can flow through the reactor from the bottom upwards, or, in the case of a fixed bed reactor or tube reactor, also from the head downwards. The hydrogen can be passed in co-current or countercurrent. Thorough mixing of the feed product and the hydrogen, a uniform distribution of flow and uniform contact with the catalyst are necessary for complete and uniform hydrogenation.A preferred variant of the process according to the invention consists in passing the liquid, olefinically unsaturated = hydrocarbons through the fixed-bed catalyst from the bottom upwards, with hydrogen in co-current.

The hydrogen is employed in the process according to the invention in an excess relative to the hydrocarbons, for example in an amount of 5 to 30, preferably 8 to 10, mols of hydrogen per mol of olefinic double bond.

The process according to the invention is carried out at a temperature of 100 to 3000, preferably of 150 to 2200C, and under a pressure of 10 to 80 bars, preferably 15 to 30 bars.

A liquid hourly space velocity LHSV of 0.1 to 8, preferably 0.2 to 6, litres of substrate per litre of reaction space per hour is maintained in the process according to the invention. Because of the abovementioned increasing difficulty of complete hydrogenation as the number of C atoms increases, it is furthermore preferable to shift the LHSV to smaller values as the number of C atoms increases. A preferred variant of the process according to the invention is thus to maintain LHSV of about 4 to about 6 when olefinically unsaturated hydrocarbons, for example oligomers of propylene or the isomeric butenes, with a main content of hydrocarbons with about 10 to 14 C atoms are used.Another preferred variant of the process according to the invention is to maintain an LHSV of about 1.5 to about 3.0 when olefinically unsaturated hydrocarbons of which the main proportion contains about 14 to about 18 C atoms are used. A further preferred variant of the process according to the invention is to maintain an LHSV of about 0.2 to about 0.5 when olefinically unsaturated hydrocarbons of which the main proportion contains about 18 to about 24 C atoms are used.

The hydrogenation according to the invention leads to saturated hydrocarbons in which the residual unsaturated content, expressed as the bromine number, is less than 1 g, preferably less than 0.4 g, of Br2 per 100 g of hydrogenated product. In a particularly preferred manner bromine numbers of less than 0.2 g of Br2 per 100 g of hydrogenated product are obtained on hydrogenation of olefinically unsaturated hydrocarbons with a C number of about 12.

The catalysts according to the invention achieve lives of greater than 8,000 hours if distilled fractions, for example those obtained from the oligomerisation of alkylenes, are employed as the olefinically unsaturated hydrocarbons. The catalysts according to the invention in any case still achieve lives of more than 4,000 hours if the olefinically unsaturated hydrocarbons employed are bottom products which remain, for example, when fractions from the oligomerisation of alkylenes are separated off and which in general contain a larger amount of impurities and are of greater complexity. Such bottom products can no longer be hydrogenated in a satisfactory manner using the palladium catalysts of the state of the art.

In addition to these noble metal hydrogenation catalysts, other nickel catalysts with nickel contents between 50 and 70% by weight, on SiO2 or Awl203 as the support, or also Raney nickel, for example containing 90% by weight or more of nickel, have also shown only unsatisfactory hydrogenation properties for the higher olefinic oligomers from the oligomerisation of alkylenes, so that only one inadequate bromine numbers of more than 2 g of bromine per 100 g of hydrogenated product have been achieved, even when only low LHSV values are applied. When used for the olefinically unsaturated hydrocarbons, with non-terminal double bonds, which are to be employed according to the invention, all the hydrogenation catalysts mentioned have considerably shorter lives than the catalysts which can be employed according to the invention. It is surprising that the catalysts according to the invention are superior to the known Pd catalysts, since Ni-containing catalysts generally require considerably higher pressures and temperatures (Ullmann, Enzyklopadie derTechnischen Chemie (Encyclopaedia of Industrial Chemistry), 4th edition, Volume 13, page 136, Verlag Chemie 1977) and since olefines with non-terminal double bonds are more difficult to hydrogenate than those which have only terminal double bonds (Tetrahedron 16, 16(1961)).

EXAMPLE 1 The feed product for the hydrogenation was a C12-isoolefine mixture which is obtained in the oligomerisation of butene mixtures. The hydrogenating activity of various Ni and Pd catalysts was investigated, in a continuous test, at a reaction temperature of 180 to 2200C, under an overall pressure of 25 bars and a partial pressure of H2 of 20 bars and at an LHSV (liquid hourly space velocity) of 5.The following table shows the results of a comparison of catalysts, in the form of the bromine numbers and the lives which were achieved.

Catalyst 1 2 3 4 5 6 7 8 9 Ni content 57 69 64 50 65 92 55 Pd content % by weight 1.8 0.5 Support kieselguhr Al2O3 SiO2 spinel H-mordenite Br number (g of Br2/100 g) 0.2 0.8 2 0.2 0.2 Life (hours) experiment deactivation deactivation 2,000- 500 hours interrupted after 500 to after 200 hours 3,000 after 8,000 hours 1,000 hours hours at full activity in all cases

Catalysts 1,2 and 3 are catalysts, according to the invention, on a kieselguhr support which contains 90.2% by weight of SiO2, 6% by weight of Al203, 0.15% by weight of TiO2, 1.6% by weight of Fe oxides, 0.7% by weight of MgO, 0,3% by weight of CaO and about 1% by weight of alkali metal oxides. The continuous experiment shows the surprisingly good life compared with Ni catalysts on other supports with various Ni contents and with Pd catalysts on various supports. The required bromine number of 0.2 was not achieved by the different catalysts.

EXAMPLE 2 The feed product was C16-isoolefins from the oligomerisation of butene mixtures. The rection conditions were a temperature of 1 80 to 2200 C, an overall pressure of 25 bars, a partial pressure of H2 of 20 bars and an LHSV of 2.5. The catalysts mentioned in Example 1 were again compared.

Catalyst 1 2 3 4 5 6 7 8 9 Ni content % 57 69 64 50 65 92 55 Pd content % 1.8 0.45 Support kieselguhr Al2O3 siO2 spinel H-mordenite Br number (g of Br2/100 g) 0.2 > 2 > 7 > 0.2 > 0.2 Life (hours) 8,000 hours 300 - 500 hours 100 hours 100 hours 100 hours

The outstanding life of catalysts 1,2 and 3 on a kieselguhr support compared with the other Ni and Pd catalysts is also surprising in this case; again, no adequate bromine numbers of preferably lower than 0.4 could be achieved with the other Ni catalysts.

EXAMPLE 3 The feed product is a bottom product which is obtained when C18-isoolefines are separated off and originates from the oligomerisation of C4 mixtures. The mixture consists of C20-isoolefines to the extent of 90% and has a residual content of 6% of C,6-olefines and 4% of isoolefines higher than C20. The reaction conditions were 200 to 2200 C, an overall pressure of 25 bars, a partial pressure of H2 of 20 bars and an LHSV of 0.3.The catalysts mentioned in Example 1 were again compared.

Catalyst 1 2 3 4 5 6 7 8 9 Ni content % 57 69 64 50 65 92 55 Pd content % 1.8 0.45 Support kieselguhr Al2O3 SiO2 spinel H-mordenite Br number (g of Br2/100 g) < 1 > 5 > 10 > 2 > 2 Life (hours) 4,000 hours 50 - 100 hours 20 hours 150 hours 30 hours

Again, only catalysts 1, 2 and 3 according to the invention can be used for the hydrogenation of this bottom product for a required bromine number of < 1 under the conditions given. All the other catalysts did not achieve the required bromine number.

Claims

1. Process for the hydrogenation of hydrocarbons with olefinic double bonds, of which at least one is non-terminal, with excess hydrogen on metal catalysts on supports, at elevated temperature and under increased pressure, characterised in that a supported nickel catalyst which has a nickel content of 50 to 70% by weight relative to the total weight of the catalyst, and of which the support is kieselguhr which has a specific surface area of 100 to 1 80 m2/g and also contains, in addition to 85 to 93% by weight of Six2,3 to 8% by weight of Al203, 0.1 to 0.2% by weight of Tit2,1 to 1.6% by weight of Fe oxides, 0.1 to 0.7% by weight of MgO, 0.3 to 1% by weight of CaO and 0.7 to 1.5% by weight of alkali metal oxides, all relative to the weight of the kieselguhr, is used, and in that a liquid hourly space velocity LHSV of 0.1 to 8 litres substrate per litre reaction space per hour is maintained.

2. Process according to Claim 1, characterised in that the liquid olefinically unsaturated hydrocarbons are passed through the fixed bed catalyst from the bottom upwards, with hydrogen in cocurrent.

3. Process according to Claims 1 and 2, characterised in that, when olefinically unsaturated hydrocarbons with a relatively high molecular weight are employed, lower hourly space velocities within the range from 0.1 to 8 are used, and vice versa.

4. Process according to Claims 1 to 3, characterised in that, when olefinically unsaturated hydrocarbons of which the main proportion has a number of C atoms from 10 to 14 are employed, a space velocity of about 4 to about 6 is maintained.

5. Process according to Claims 1 to 3, characterised in that, when olefinically unsaturated hydrocarbons of which the main proportion has a number of C atoms from about 14 to 1 8 are employed, a space velocity of about 1.5 to about 3.0 is maintained.

6. Process according to Claims 1 to 3, characterised in that, when olefinically unsaturated hydrocarbons of which the main proportion has a number of C atoms from 18 to 24 are employed, a space velocity of about 0.2 to about 0.5 is maintained.