NO127502B - - Google Patents

Description

Process for the epoxidation of olefins with

hydroperoxides.

It is known to convert olefin compounds into corresponding oxirane compounds by reacting them with an organic hydroperoxide according to the following general reaction equation:

The resulting hydroxyl compound from this reaction can, if desired, be converted back into a hydroperoxide compound. When there is a carbon atom ', bearing at least one hydrogen atom, as neighboring atom to the carbon atom bearing the hydroxyl group, the regeneration takes place Cfr. at 12g-ll/06,

in

usually most beneficial in dehydration, hydrogenation and oxidation, represented by the following reaction nucleus:

It is often possible to carry out the first two steps simultaneously.

It will be understood that when the olefin compound which is an intermediate in the above scheme is a salable product, the hydrogenation and oxidation steps can be omitted. If the hydroxyl compound is a salable product, it may even be advantageous to omit the dehydration step.

In general, hydroperoxides are produced in a manner well known to those skilled in the art by an oxidation reaction, represented by the following general reaction equation:

where R represents a monovalent hydrocarbon residue which may or may not be substituted. (It will be understood that the last step in the above regeneration scheme is covered by the latter general reaction equation).

The group R preferably has from 2 to 10 carbon atoms. Most advantageously, it is a hydrocarbon residue, . in particular a secondary or tertiary alkyl or aralkyl group having from 5 to 10 carbon atoms. Particularly preferred among these groups are the tertiary alkyl and secondary or tertiary aralkyl groups, comprising e.g. tertiary butyl, tertiary pentyl, cyclopentyl 1-phenylethyl-1, 2-phenylpropyl-2 and the various tetralinyl radicals which arise from the elimination of a hydrogen atom from the aliphatic side chain in the tetralin molecule.

Aralkyl hydroperoxides, in which the hydroperoxy group is bound to the carbon atom in an alkyl side chain which is bound directly to an aromatic ring, including 1-phenylethyl-1-hydroperoxide and 2-phenylpropyl-2-hydroperoxide, are often named after the corresponding hydrocarbons, e.g. e.g. ethylbenzene hydroperoxide and cumene hydroperoxide. This practice will also be followed in the following.

It will be understood that when ethylbenzene hydroperoxide is used,

the resulting hydroxyl compound 1-phenylethanol-1, which also

can be called methylphenylcarbinol and which can be dehydrated to

one, and that when cumene hydroperoxide is used, the resulting hydroxyl compound is 2-phenylpropanol-2, also called dimethylphenylcarbinol, which can be dehydrated to alpha-methylstyrene. Both styrene and alpha-methylstyrene are of course industrially usable products,

and it can therefore often be advantageous to use and/or sell them as such and not to regenerate ethylbenzene and cumene respectively.

Tertiary amylenes that are useful as isoprene precursors

ere, can be obtained by dehydration of the alcohol formed using tertiary pentyl hydroperoxide.

For the sake of brevity, the term hydrocarbon will hereafter be generally used to denote the compound RH as defined above, although, as discussed, R can also be a substituted hydrocarbon residue.

The organic hydroperoxide reactant used as starting material can be in a diluted or concentrated, purified or impure state. It is known that 5 to 70% by weight solutions of the hydroperoxide in the corresponding hydrocarbon can usually be easily prepared by oxidation of said corresponding hydrocarbon. Isolation of the hydroperoxides becomes more difficult when the volatility of the hydrocarbons decreases and the use of the solutions as such can then be advantageous. Suitable methods for oxidizing the relevant hydrocarbons are well known to the person skilled in the art.

Solutions of hydroperoxides in the corresponding hydrocarbons, obtained by known oxidation techniques, also usually contain a proportion of the alcohol that is formed by reduction of the hydroperoxide, and this alcohol can also be partially oxidized to the corresponding ketone. Thus, a solution of ethylbenzene hydroperoxide in ethylbenzene generally also contains methylphenylcarbinol and methylphenylketone. After the reaction with an olefin compound, the methyl-phenylketone can be converted to methylphenylcarbinol by hydrogenation, and the total amount of methylphenylcarbinol finally obtained can be converted to styrene, and, if desired, further converted to ethylbenzene.

In principle, any organic compound that has at least one olefinic double bond can be reacted with a hydroperoxide in the manner described above. The compounds may be acyclic, monocyclic, bicyclic or polycyclic, and they may be mono-olefinic, diolefinic or poly-olefinic. If there is more than one olefinic bond, these can be either conjugated or non-conjugated. Generally preferred are olefinic compounds with from 2 to 60 carbon atoms. Although substituents, which should preferably be relatively stable, may be present, acyclic mono-olefinic hydrocarbons of from 2 to 10 carbon atoms are of particular interest. Such hydrocarbons include e.g. ethylene, propylene, isobutylene, hexene-}, octene-1 and decene-1. Butadiene can be mentioned as an example of a diolefinic hydrocarbon. Substituents can, if such are present, e.g. be halogen atoms or oxygen, sulfur and nitrogen atoms together with hydrogen and/or carbon atoms. Of particular interest are olefinically unsaturated alcohols and halogen-substituted, olefinically unsaturated hydrocarbons, comprising e.g. allyl alcohol, crotyl alcohol and allyl chloride.

Oxirane compounds are industrially applicable materials and many are commercial chemicals, especially olefin oxides such as e.g. ethylene oxide and propylene oxide. Like for example. described in the U.S. patents Nos. 2,815,5, 2,871,219 and 2,987,98, propylene oxide can be converted into useful polymer products by polymerization or copolymerization. Also of commercial interest is epichlorohydrin which can be obtained from allyl chloride and which, if desired, can be converted to glycerol. Glycerol can of course also be produced from oxirane compounds which are formed when starting from allyl alcohol]

It is well known that ethylene oxide is produced on a large scale by reacting ethylene with molecular oxygen using a silver-containing catalyst. Another route to ethylene oxide consists in the addition of hypochlorous acid to the double bond followed by dehydrochlorination. This route has also been found to be very suitable for the production of propylene oxide. However, the reaction of propylene with a hydroperoxide, as mentioned above, is a very promising alternative. Particularly advantageous is the epoxidation of propylene with ethylbenzene hydroperoxide according to the following reaction equation:

It has already been pointed out above that styrene can then be obtained as a valuable by-product.

The present invention relates to an improvement of the above-

for said known method, in which one or more olefin compounds are reacted with one or more organic hydroperoxides to form one or more oxirane compounds. The improvement consists in the use of a special type of catalyst. Various catalysts have been discussed in previous publications. E.g. described in the U.S. Patent No. 2,754,325 the use of solutions of heteropolyacids containing transition metals, such as chromium, molybdenum and tungsten, and U.S. Pat. patents Nos. 3,350,422 and 3,351,635 describe the use of solutions of transition metal compounds (V, Mo, W, Ti, Nb, Ta, Re, Se, Zr, Te and U). However, the known catalysts are generally effective only when they are homogeneously dispersed in the reaction mixture. It would of course be advantageous if catalysts or catalyst compositions which are virtually insoluble in the reaction mixture could be used, since such heterogeneous catalyst systems can be separated from the reaction products much more easily.

The invention relates to the use of a catalyst which is essentially insoluble in the epoxidation reaction mixture, so that a heterogeneous system is provided. It has surprisingly been found that the catalyst used according to the invention is quite active and leads to a high conversion of the hydroperoxide, resp. -oxides, as it possesses high selectivity towards the relevant oxirane compound-

see, this selectivity being defined as the molar ratio of formed oxirane compound to converted hydroperoxide.

In general, the reaction is carried out in the liquid phase using solvents and/or diluents which are liquid at the reaction temperature and pressure and approximately inert towards the reactants as well as the products. Presence of reactive materials such as e.g. water, should preferably be avoided. A substantial part of the solvent may consist of materials present in the hydroperoxide solution used. Preferred solvents which can also be added are mononuclear aromatic, e.g. benzene, two-

luene, chlorobenzene, bromobenzene, ortho-dichlorobenzene and alkanes,

e.g. octane, decane and dodecane. However, an excess of the olefinic reactant may also serve as a solvent along with the solvent material introduced with the hydroperoxide,

so that there is no need to add any additional solvent. In most cases, however, an added solvent is used. The total amount of solvent can be up to 20 mol per moles of hydroperoxide.

The reactions generally take place at moderate temperatures and pressures, especially temperatures in the range from 0°C to 200°C, the range from 25°C to 200°C being preferred. The exact pressure is

not critical as long as it is sufficient to keep the reaction mixture in a liquid state. Atmospheric pressure can be satisfactory, pressure in the range from 1 to 100 ata is generally preferred.

After completion of the reaction, the liquid mixture consisting of the desired products can be easily separated from the solid catalyst material. The liquid mixture can then be worked up using any suitable known methods, e.g. fractional distillation, selective extraction and filtration. The solvent, the catalyst and any unreacted olefin or hydroperoxide can be recycled for further use. The method according to the invention can be successfully carried out with the catalyst in the form of a slurry, a moving bed or fluidised bed. However, a solid catalyst bed seems most advantageous on an industrial scale. The method can be carried out in portions, but also semi-continuously or continuously. The liquid containing the reactants can be passed through the catalyst bed so that the effluent from the reaction zone is completely or practically free of catalyst material.

The catalyst used according to the present invention is virtually insoluble in the reaction mixture, so that a heterogeneous system is provided. The catalyst comprises zirconium chemically bonded to an inorganic silicon-containing solid,

and the proportion of zirconium in the catalyst, calculated as zirconium dioxide; .1, is in the range from 0.1 to 25% by weight, while the inorganic silicon holding solid contains at least 50% by weight, preferably at least 90% by weight silicon calculated as silicon dioxide, and it has a specific surface area in the range from 25 to 800 m / g.

Preferred as silicon-containing solid in the catalyst

which are used according to the invention, are e.g. synthetic, po-

roasted silica in a relatively dense, packed form, consisting of particles of amorphous silica flocculated or bun-

together, including silica gel and fused silica. The production and properties of such materials are described by R.G. Iler i hand book "The Colloid Chemistry of Silica and Silicates", Cornell University Press, New York, 1955, Chapter VI and in the U.S.

patent No. 2,657,149. Among the commercially available silica gels are those with a specific surface area in the range from 25 to 700 m 2 /g and a pore volume in the range of 0.3 to 1.3 ml/g,

and which consist of at least 99% silicon dioxide, the most suitable.

However, synthetic silicon dioxide powders are also suitable.

be composed of particles of amorphous silicon dioxide flocculated in loosely packed, easily disintegratable, loosely bound aggregates,

such as e.g. fumed silicon dioxide obtained by burning hydrogen and oxygen with silicon tetrachloride or -tetrafluo-

ride. Such products are manufactured commercially and sold by various companies, e.g. Cabot Corporation ("Cab-O-Sil") and Degussa ("Aerosil"). Among these products are those with a spe-■2

specific surface area in the range from 50 to 400 m /g and a particle size in the range from 0.007 to 0.05 microns, and which consist of at least 99% silicon dioxide, are generally the most suitable.

Furthermore, suitable inorganic siliceous solids include the crystalline alumina silicates which on

the advice is known as molecular sieves, as well as naturally occurring crystalline mineral silicates> including e.g. asbcstmine-

minerals such as serpentine (hydrous magnesium silicate), clay minerals such as hectorite (magnesium lithium silicate), kaolins and bentonites,

as well as mica minerals such as phlogopite (potassium magnesium aluminum silicate) and vermiculite (a hydrous magnesium silicate). However, synthetic, amorphous, inorganic silicon-containing solids are preferred, especially those which essentially consist of pure silicon dioxide, e.g. at least 95% silicon dioxide.

IN

It may be advantageous to incorporate promoters into the catalysts used according to the present invention, especially compounds of alkaline earth metals, comprising e.g. magnesium, calcium, strontium and barium. Preferred are the oxides and such compounds which are easily converted into oxides. To carry out this conversion, it is desirable to pre-treat the originally produced catalyst composition before it is used. The proportions of promoters) are not critical, but proportions exceeding 10% by weight, calculated as metal on the catalyst carrier, are usually not necessary. The incorporation of promoters is particularly advantageous when inorganic silicon-containing solids with strongly acidic sites are used, e.g. when the intrinsic acidity is less than -3. The intrinsic acidity/ generally represented by pK , is determined by titration of the material in question with -a suitable base in the presence of dye indicators, as for example described in U.S. patent No. 2,868,688.

The catalyst used according to the present invention can be produced by conventional techniques, such as e.g. dry mixing followed by calcination, co-gelation, co-precipitation, impregnation and ion exchange. For example, a mixture of a zirconium salt and a silica sol can be combined, after which the material is dried and ground to a suitable size. Alternatively, the coagulated materials can be slurried and spray dried. However, the catalyst can, for example, also be produced by reacting hydroxyl groups on the surface of the inorganic silicon-containing solid with a zirconium salt, e.g. by the method described in U.S. Patent No. ?.116,542, 5,270,459 or 5,274,120. In yet another technique, a pyrogenic catalyst, particularly a pyrogenic zirconia-silica product, can be prepared by combusting hydrogen and oxygen together with a mixture of a silicon tetrahalide and a zirconium halide.

The catalyst can be subjected to a pre-treatment before it is used in the process. As a rule, it is preferred to do so in order to achieve a higher activity. As a rule, the pretreatment suitably consists of heating the catalyst in an atmosphere of a non-reducing gas, such as e.g. nitrogen, argon, carbon dioxide or of an oxygen-containing gas, such as e.g. air, However, the most suitable method of pretreatment generally depends on the form of the chemical combination in which the zirconium component is used. In many cases, the zirconium compounds must be converted to oxide, e.g. if the catalyst originally contains zirconium in the form of its tetrachloride or as a mixture of tetrakismethylpropylamine-zirconium and KC1. The conversion can usually conveniently be carried out by heating in a non-reducing atmosphere, especially at temperatures in the range from 250°C to 800°C for periods varying from 1

to 18 hours.

The catalyst used according to the invention can be used in any usual physical form, e.g. in the form of a powder, as well as flakes, balls or pellets.

The catalyst used according to the present invention may also include other components which are inert over

for the reactants and products. Other substances known to catalyze the epoxidation reaction may be present in combina-

tion with the catalysts according to the present invention, provided that the catalytic activity is not reduced by the combination. In general, the catalysts 1 according to the invention may further comprise up to 10% by weight of oxides or hydroxides of boron, tin, niobium, tantalum, chromium, molybdenum, tungsten, rhenium,

uranium, bismuth and rare earth metals with atomic numbers from and including 57 to and including 71*

EXAMPLE I - Zirconium on Silica Catalyst from Pyro-

gent silicon dioxide and ZrCl^

A mixture of 25 g of commercial pyrogenic silicon di-

oxide with a specific surface area of 590 m o/g (Cabot Corporation's type "EH-5 Cab-0-Sil"), and 1700 ml of n-heptane were dried by heating under reflux in a glass reactor equipped with a "Dean Stark" -collector (for collecting water heptane azeotrope) for a period of 19 hours. After cooling to }0°C, 2.89 g (15.2 millimoles) of zirconium tetrachloride was added to the reactor and the reaction mixture was heated to approx. 95°C up to approx. 15.2 millimoles (one equivalent on the basis of ZrCl^) of hydrogen chloride had evolved.

The evolved hydrogen chloride was removed by means of a current

of dry nitrogen and passed to a scrubber containing dilute alkali. About. 10 ml of water was then added for approx. 0.5 ml portions to initiate the formation of additional hydrogen chloride. After a total reaction time of approx. 16 hours at 95°C stopped the evolution of hydrogen chloride. The reaction mixture was subjected to evaporation at reduced pressure and 6o°C and the residue dried at 115°C at reduced

press hard for 2 days. The resulting product contained 1.55 wt-J of zirconium, calculated as metal.

ben thus prepared catalyst was tested on the epoxidation of a number of olefins with t-butyl hydroperoxide (TBHP) in , a 100 ml glass reactor. The reaction conditions, the hydroperoxide conversion and the olefin oxide selectivity on the basis of converted hydroperoxide are given in Table I.

EXAMPLE II - Zirconium on silicon dioxide by impregnation

and calcination

A 10 g sample of commercial fumed silica with a specific surface area of 200 m /g and a particle size of 500 Å (Cabot Corporation's type "MS/7 Cab-O-Sil") was contacted with a solution of 0.559 g of Zr(N0 -j)^*5H2O in 50 ml of water. The impregnated silica was dried at a temperature of 150°C and then calcined at a temperature of 800°C for 2 hours. The resulting product contained 1.55 wt-# of zirconium oxide.

A 1 g sample of the thus prepared catalyst

was brought into contact with 42 g of 1-octene and 5*5 g of t-butyl hydroperoxide at 110°C for 12 hours. Analysis of the product mixture showed 46.1% conversion of the hydroperoxide and 67.5% selectivity to 1-octene oxide on the basis of converted hydroperoxide. EXAMPLE III - Zirconium on silicon dioxide from SlCl^ and ZrCl^

A mixture of 0.07 g zlrkonium tetrachloride in 56.9 g zyllium tetrachloride (Matheson, Coleman and Bell, semiconductor grade) was added dropwise to 500 ml deionized water heated to approx. 70°C. The resulting mixture was evaporated on a water bath under reduced pressure and the residue dried at 150°C for 4 hours. Pror duct contained o.47 weight-JÉ zirconium, calculated as; metal.

A 1 g sample of the thus prepared catalyst was

brought into contact with 26.2 g of cyclohexene, 4.5 g of t-butylhydroper-

oxide and 2.1 g of nonane in a 100 ml glass reactor at 85°C for 18 hours. Analysis of the product mixture showed 60# conversion of the t-butyl hydroperoxide and 42# selectivity to cyclohexene oxide on the basis of converted hydroperoxide.

EXAMPLE IV - Silicon on zlrkonium oxide from zirconium oxide and

SlCl^

A 20 g sample of commercial zinc oxide with a spe-

specific surface area of 169 m /g, 750 ml of n-heptane was azeotrop-

ice dried by heating under reflux in a glass reactor with collection device for water-heptane azeotrope for a period of 18 hours. After cooling to 55°C, 5.5 ml of silicon tetrachloride was added to the reactor and the reaction mixture heated to 50°C

until approx. 25 millimoles of hydrogen had evolved. The evolved hydrogen chloride was removed with a stream of dry nitrogen and passed to a scrubber containing dilute alkali. About. 10 ml of water was then added for approx. 0.5 ml portions to initiate further hydrogen chloride evolution. After an additional 0.105 mol of hydrogen

chloride had evolved, the reaction was stopped. reaction mix-

none was evaporated under reduced pressure at 60 C and the residue dried

one at 100°C and a pressure of l80 mm Hg for 5 days. The resulting product contained 5.9 wt-# of silicon calculated as elemental silicon.

A 1 g sample of the thus prepared catalyst was

contacted with 56.5 g of 1-octene, 4.5 g of t-butyl hydroperoxide and 2.1 g of nonane in a 100 ml glass reactor at 109°C for 22 hours. To reach-

lysis of the product mixture showed 54.2# conversion of the t-butyl hydroperoxide and 71JÉ selectivity to 1-octene oxide on the basis of

formed hydroperoxide.

EXAMPLE V - Zirconium and other metals on non-silicon carriers (for comparison)

Compositions consisting of a number of metal oxides including zinc oxide supported on silica-free supports were tested as catalysts for the epoxidation of 1-octene with t-butyl hydroperoxide. The reaction conditions and results are given in Table II. The catalysts for experiments A-G were prepared by

react a metal halide with either pyrogenic alumina with

a specific surface area of 100 m/g, or Mg(OH)Cl with a specific surface area of approx. 20 m /g, or zlrconium oxide with a specific surface area of 169 m /g by a method similar to that of Example I. In experiment H, a commercial composition with 2.5 wt.JÉ Co and 9.5 wt.# was used Mo on aluminum oxide. In experiment I, the epoxidation of 1-octene with t-butyl hydrogen peroxide was carried out in the absence of catalyst.

EXAMPLE VT - Metals other than zirconium on silicon dioxide, (for comparison)

Several metal-silica compositions were prepared and tested as catalysts for the epoxidation of 1-octene with t-butyl hydroperoxide (TBHP). The epoxidation reaction conditions and results are set forth in Table III. In Experiments A-C, the catalyst compositions were prepared by surface reaction between a metal halide and a commercial fumed silica (Cabot Corporation's "EH-5 Cab-O-Sil") by a method similar to that of Example I. In Experiments E-J, the catalyst compositions were prepared by co-hydrolysis of a metal halide and silicon tetrachloride by a method similar to that in Example III. In experiment K, the catalyst composition was prepared by contacting 50 g of commercial silica gel, which had a specific surface area of 750 m /g, with a solution of 0.625 g of chromium trioxide in 20 ml of water, drying the impregnated silica gel at 150°C and calcining at 500°C for 2 hours. In experiment L, the catalyst composition was prepared by contacting 20 g of commercial magnesium trisilicate (10.2 wt-# Mg and 55.6 wt-# Sl) having a pore volume of approx. 1.1 cnrVg, with a solution of 0.1 g of chromium trioxide in 25 ml of water, dry the impregnated magnesium trisilicate at 150°C and then calcine at 500°C overnight. In experiment M, the catalyst composition was prepared by contacting 10 g of commercial fumed silica having a surface area of 200 ra /g (Cabot Corporation's type "MS/7 Cab-O-Sil"), with a solution of 0.508 g of tungstic acid (RgWO^) , 45 ml of 25% by weight ammonium hydroxide and 5 ml of 50% by weight hydrogen peroxide, dry the impregnated silica at 150°C and then calcine at 800°C for 2 hours. In experiment D, the rhenium oxide-silica product (6.9 wt-JÉ Re) was prepared by contacting 10 g of commercial fumed silica with 1 g of rhenium acid (HReO^) in 50 ml of water and subsequent drying of the product at 200°C.

EXAMPLE VII - Various metal compounds without sllllsium-containing material (for comparison)

In a series of experiments, several of the metal compounds were tested as heterogeneous catalysts for the epoxidation of 1-octene with t-butyl hydroperoxide. In each experiment, a 1 g sample of the metal compound was contacted with 56.5 to 42 g of 1-octene and from 4.5 to 5.5 g of t-butyl hydroperoxide. The reaction conditions and results are given in Table IV.

0

Claims (1)

Process for producing oxirane compounds by reacting one or more olefinic compounds with one or more organic hydroperoxides in the presence of a catalyst, and using inert solvents and/or diluents and under such a pressure that the reaction mixture is liquid when the reaction proceeds, characterized in that a catalyst is used which is virtually insoluble in the reaction mixture, so that a heterogeneous system is provided, in that the catalyst comprises zirconium chemically bound to an inorganic silicon-containing solid substance, further that the proportion of zirconium in the catalyst calculated as zirconium dioxide is in the range from 0, 1 to 25% by weight, that the inorganic silicon-containing solid contains at least 50% by weight, preferably at least 90% by weight silicon, calculated as silicon dioxide, and has a specific surface area in the range from 25 to 800 m2/g.