NO136925B - PROCEDURES FOR OXFILILATION OF GAS PHASE OLEFINS. - Google Patents

Description

It is known that olefins can be converted into gaseous

phase with organic carboxylic acids and oxygen or oxygen-

containing gases to oxacylation products such as vinyl acetate, allyl acetate or methallyl acetate. The reaction preferably takes place in the presence of carrier catalysts containing palladium or palladium salts and additives such as gold, gold salts, cadmium, cadmium salts, bismuth, bismuth salts, alkaline earth salts and alkali salts. Generally, the active components are applied to a porous support, with for example silicic acid, aluminum oxide, aluminosilicates, titanium oxide, zirconium oxide, silicates, silicon carbide or coal being suitable as a catalyst support. Particularly suitable are silicic acids with a specific surface from 40 to 350 m/g, and an average pore radius from 50 to 2000 Å.

The invention relates to a process for the oxacylation of olefins in the gas phase by reacting olefins with 2-4 carbon atoms with carboxylic acid with 2-4 carbon atoms and oxygen in the presence of a catalyst containing palladium salts and additives on a support having a specific surface area between 40 and 350 m /g, and a total pore volume between 0.4 and 1.2 ml/g, the method being characterized in that less than 10%

of the total pore volume of the catalyst carrier is formed by micropores with a diameter smaller than 30 Å.

By using this carrier, it is possible to significantly increase the catalyst's performance at the same content of active substances.

fer and the same reaction conditions. The advantages of the method according to the invention lie in the fact that with this increase in performance, catalyst and reactor volume can be saved in new plants, which leads to a considerable reduction in construction costs, or that in existing plants the capacity can be increased significantly without conversion, thus saving investment costs for a plant expansion .

Supported catalysts for oxacylations, where less than 10% of the total pore volume of the catalyst support is formed by micropores with a diameter of less than 30 Å, have not previously been discussed in the literature. It is true that there are publications which recommend certain "average pore radii" for carrier catalysts, for the carrier, for example, silicic acid carriers are mentioned in Norwegian explanatory document no. 124,517 which preferably have an "average pore radius" from 50 - 600 Å, but it cannot be concluded from this that the literature recommends or specific minimum size for the carrier pores is mentioned. The term "mean pore radius" is indeed misleading, as it denotes a quantity which is in no way an average value in the mathematical sense. The so-called "mean pore radius" is a fictitious size assigned to the carrier X for classification. It denotes the radius that spherical pores of a fictitious support (which by definition exclusively have pores of the same radius) would have if one determines that the 'total surface area and the total pore volume of the fictitious support should be exactly as large as the corresponding values' of the real carrier X. Thereby, it is necessary as a further assumption that the overall surface of the fictitious carrier is essentially the sum of the internal surface of the spherical equal-sized pores. Under this assumption, one can from the measurable values for total surface and total pore volume of the real carrier X calculate the pore radius of the fictitious carrier. This fictitious radius' is referred to in the literature as the "mean pore radius" of the real carrier X. However, it is not possible on the basis of this

to say something about the mean value of the pore radius (mathematical sense; of the real carrier X. To determine such a mean value, one must know the number of pores and all pore radii of the real carrier X, both of which are, however, in reality unknown.

The usual inert substances, such as silicic acid, silicates, aluminosilicates, titarium oxide, zirconium oxide or different types of glass, are used as a carrier material.

In order to avoid the formation of micropores, it is best to start from molten particles without internal pores, whose average particle diameter is not below 80 Å. Since glassy molten small particles almost always have a spherical shape, the smallest pore diameter results from the densest ball packing. The upper limit for the average particle diameter is evident from the required lower limit for the overall surface of the carrier. As this

is approximately the sum of the individual particle surfaces and should not fall below 40 m/g, the average particle size will not be significantly above 1000 Å, and usually not above 600 Å.

These particles without pores can, for example,

obtained by hydrolysis of silicon, zirconium and titanium tetrachloride in a hydrogen-air or high-pressure gas flame. Also when melting micronized substances such as aluminosilicate, silica gel or glass,

can these particles be produced under conditions which prevent the formation of larger droplets and thus a reduction of the total surface area of the carrier below the value of 40 m^/g, e.g. by blowing the particles diluted with air or inert gas through a sufficiently hot flame, and allowing them to cool before collecting

ning below the melting point.

The processing of these small particles into larger spheres, tablets or grains of 0.1 - c. 0 mm diameter suitable for catalyst production can take place in different ways<, >for example by forming the powder-shaped mass with a diluted solution of mineral glue by pelleting , granulation, extrusion or tableting brings into the desired form and. transfers the adhesive by burning in a poorly soluble form.

Examples of inorganic adhesives include water glass, silicic acid sol, aluminum oxide sol, kaolin, bentonite. It is also possible to suspend the dough-formed particles with an aqueous sol in a water-immiscible solvent or diluent and to allow the sol to gel, which leads to particularly porous products. You can also atomize a thin mixture of the particles in a sol through a nozzle and let the sol gel in free fall. In order to avoid damage to the gel-formed yet soft droplets, they can be sprayed upwards and collected in any liquid (e.g. water) or an air or gas flow can be directed towards the droplets which reduces their collision speed and at the same time drying increases resistance. In this way, you can set almost any grain size.

The carriers thus formed are mixed in the usual way

with the active components, for example for oxacetylation of ethylene to vinyl acetate by impregnation with a solution of palladium acetate, cadmium acetate and potassium acetate and potassium acetate in acetic acid and subsequent drying or for oxacetylation of propylene to allyl acetate and of i-butylene to methylyl acetate via impregnation with an acetic acid solution of palladium acetate,

gu 1-1 acetate, .bismuth- and. potassium acetate and subsequent drying.

o :.;.. - -" 'The-actual' dxacylation' takes place by conducting

. carboxylic acid, olefin and oxygen or oxygen-containing gases at temperatures of 100-250°C and pressure from 1' t il • 10 ato above that of . carrier, and • active. components consisting of a catalyst, ■ id the unconverted products can be cycled. -.'■•■ t :•';.'.. Thereby, it is advantageous to choose concentration ■■for the conditions - so that the reaction mixture is 'outside' the known explosion limits. This is most easily achieved by keeping the oxygen concentration low, for example between 3 and 8% of that used: gases. Under these circumstances, however, it is also advantageous to dilute with inert gases such as nitrogen or carbon dioxide. Those for the method according to the invention suitable olefins must be volatile under the reaction conditions. Ethylene, propylene and i-butylene are particularly suitable. "L Unsubstituted,-■ saturated aliphatic are converted: monocarboxylic acids with 2 to 4 . carbon atoms such as propionic acid, n-butyric acid, and i-butyric acid, especially preferred acetic acid. The carbo'^-syllic acids can optionally be used in the form of aqueous solutions. It is appropriate to carry out the reaction in the presence of one or more alkali salts of the carboxylic acids to be reacted. Sodium salts and potassium salts are preferred, particularly potassium salts are preferred. The preferred amounts of alkali carboxylates are between 0.1- and 10 ..véc-t%,' referred to 1 the weight of the catalyst system: Which-consists of .;carrier material and-catalytically' active substances. "-'"' ■'■■•' ■"• ...:' •";..'...-' A particularly favorable technical •out Ise's form consists in' adding ;alkaline saltery 'of the carboxylic acids-'continuously' or discontinuously .to 1 the catalyst: 'under ' the reaction, 'when the addition^ of...k-carboxylic acid pure alkali salts amounts to between G-,1 to 400. ppm:, preferably between'1.and vlOO ppm of the' used':car-' carboxylic acids... ■ . ' '■-■".'■.• - ,- ^ Progress the details "according to the invention can be carried out in fixed; bed or. also in fluidized bed or fluidized bed reactors. Fixed bed is usually preferred..." - ■' .';'. };•:.• :... :. / In~ the following-; table ver. the opposite The results are in the examples, of which the advantages of the method according to the invention are apparent. is very surprising, and could not be predicted - as the effective: molecular diameters are significantly lower, namely between -4 Å and -6 Å. Thus, e.g. oxygen an effective radius of 2.8 Å, carbon dioxide an effective radius of 2.8 ethylene an effective radius of 4.2 Å,

propylene an effective radius of 5.0 Å, ....... i-butylene an effective radius of 5»6 Å.

One cannot therefore explain the lower performance of

the usual supports with a part of the specific surface inaccessible to the reactants. Furthermore, molecular sieves with a pore width of 10 Å are known to be particularly good catalysts, even for the production of such towering molecules as diisoprqpyjLbenzene from benzene and propylene, so that it is unlikely to have a steric hindrance of the reaction in the small pores...,

The examples listed below were carried out in a . apparatus with parallel-connected reactors which enables the comparison of different catalysts under the same reaction conditions. The reactors were designed for direct recycling of the reaction components. The performances achieved herein are only comparative performances under the same reaction conditions. They are not identical to the maximally achievable performance under other conditions, for example in circulating gas or fluidized bed processes.

Example 1.

Vinyl acetate of ethylene, acetic acid and oxygen.

Comparative example la with ordinary carrier on basic silica gel.

1 liter corresponding to 400 g of a granular silica gel carrier with a specific surface of 350 m<2>/g, a pore volume of 1.0 ml/g and a grain size of 2.5 - 7 mm is impregnated with a solution of

10.7 g palladium acetate

19.0 g of cadmium acetate

20.0 g of potassium acetate i

370 ml acetic acid

and dried.

1 liter of the catalyst is filled in a reaction tube of 32 mm internal diameter. At 5 ato pressure and an internal temperature of 180°C, the catalyst is passed per hour a mixture of 850 NI ethylene, 75 NI oxygen and 870 g acetic acid and obtains under these conditions a catalyst performance of 215 g vinyl acetate/hour.

Comparative example 1b with a conventional carrier based on a silicic acid layer lattice.

1 liter corresponding to 564 g of a silicic acid carrier with a specific surface of l60 m /g, a pore volume of 0.73 ml/g and a sphere size of 6 mm is impregnated with

10.7 g palladium acetate

19.0 g of cadmium acetate

20.0 g of potassium acetate i

395 ml acetic acid

and dried.

In the turnover of ethylene, oxygen and acetic acid

of 1 liter of this catalyst under the same conditions as in example la, the catalyst yield amounts to 220 g of vinyl acetate per hour.

lc) Example with the method according to the invention with a

■silicic acid carrier practically without micropores below 30 Å diameter. 450 g corresponding to 1 liter of a silicic acid carrier without micropores with a specific surface of 205 m /g and a pore volume of 0.85 ml/g is impregnated with a solution of

10.7 g palladium acetate

19.0 g of cadmium acetate

20.0 g of potassium acetate i

350 ml acetic acid

and dried.

Ethylene, oxygen is fed over 1 liter of the catalyst

and acetic acid under the same conditions and in the same amounts as in examples la and lb. The catalyst yield was 205 g of vinyl acetate per hour.

Example 2.

Allyl acetate of propylene, acetic acid and oxygen.

2a) Comparison example with ordinary silicic acid carrier.

1 liter corresponding to 400 g of a granular silica gel

carrier with a specific surface of 350 m /g, a pore volume of

1.0 ml/g and a grain size of 2.5-7 mm is impregnated with a solution of

10.7 g of Pd acetate

6.5 g barium acetoaurate III

5.9 g bismuth acetate

46.0 g of potassium acetate i

360 ml acetic acid

and dried.

1 liter of the catalyst is filled into the reactor mentioned in example la and passed over the catalyst at 5 ato pressure and 180°C per hour with a mixture of 850 NI propylene, 75 NI

oxygen and 870 g of acetic acid. Under these conditions, the catalyst yield amounts to 180 g of allyl acetate per hour.

2b) Comparative example with a normal support on the basis of a silicic acid layer lattice.

564 g corresponding to 1 liter of a silicic acid carrier with

a specific surface of l60 m /g, a pore volume of 0.73 ml/g and a ball size of 6 mm is impregnated with a solution of

10.7 g palladium acetate

6.5 g barium acetoaurate III

5.9 g bismuth acetate

46.0 g of potassium acetate i

365 ml acetic acid

and dried.

In the turnover of propylene, oxygen and acetic acid

on 1 liter of this catalyst under the conditions mentioned in example 2a, the catalyst yield amounts to 190 g of allyl acetate per hour. 2c) Example with the method according to the invention with a silicic acid carrier practically without micropores below 30 Å in diameter.

450 g corresponding to 1 liter of a silicic acid carrier

according to the method according to the invention without micropores, which has a specific surface of 205 m<2>/g and a pore volume of 0.85 ml/g,

impregnated with a solution of

10.7 g palladium acetate

6.5 g barium acetoaurate III

5.9 g bismuth acetate

46.0 g of potassium acetate i

340 ml acetic acid

and dried.

Propylene, oxygen and acetic acid are fed over 1 liter of the catalyst under the same conditions and in the same quantities as in examples 2a and 2b. The catalyst yield amounts to 280 g of allyl acetate per hour.

Example 3.

Metallylacetates of isobutylene, acetic acid and oxygen. 3a) Comparison example with a normal silica gel carrier. 1 liter of the catalyst mentioned in example 2a is filled into the reactor mentioned in example la and passed over the catalyst at 5 ato pressure and 180°C per hour a mixture of 850 NI isobutylene, 75 NI oxygen and 870 g acetic acid.

Under these conditions, the catalyst surfaces amount to 185 g of methallyl acetate per hour.

3b) Comparative example with a conventional carrier based on a silica layer lattice.

In the reaction of isobutylene, oxygen and acetic acid on 1 liter of the catalyst mentioned in example 2a under the conditions mentioned in example 3a, the catalyst yield amounts to 170 g rnetallyl acetate per hour.

3c) Example with the method according to the invention with a silicic acid carrier practically without micropores below 30 Å diameter.

Over 1 liter of the catalyst mentioned in example 2c, isobutylene, oxygen and acetic acid are fed under the same conditions and in the same quantities as in examples 3a and 3b. The catalyst yield amounts to 270 g rnetallyl acetate per hour.

Example 4.

Allyl propionate from propylene, propionic acid and oxygen. 4a) Comparison example with a normal silica gel carrier.

Over 1 liter of the catalyst mentioned in example 2a is fed at 5 ato pressure and 180°C per hour a mixture of 850 NI propylene, 75 NI oxygen and 1075 propionic acid. You get per hour 173 g allyl propionate.

4b) Comparative example with a regular carrier based on a silica gel layer lattice.

Over 1 liter of the catalyst mentioned in example 2b is fed per hour at 5 ato pressure and 180°C 850 NI propylene, 75 NI oxygen and 1075 g propionic acid. You get 180 g of allyl propionate per hour.

4c) Example with the method according to the invention with a silicic acid carrier practically without micropores below 30 Å diameter.

Propylene, oxygen and propionic acid are fed over 1 liter of the catalyst mentioned in example 2c under the same conditions and in the same quantities as in examples 4a and 4b. The catalyst performance amounts to 265 g of allyl propionate per hour.

Patent claim:

Process for oxacylation of olefins in the gas phase by reacting olefins with 2-4 carbon atoms with carboxylic acid with 2-4 carbon atoms and oxygen in the presence of a catalyst containing palladium salts and additives on a support having a specific surface area between 40 and 350 m /g , and a total pore volume between 0.4 and 1.2 ml/g, characterized in that less than 10% of the catalyst carrier's total pore volume is formed by micropores with a diameter less than 30 Å.

Claims (3)

1. Device for fork stackers in connection with a tractor that is equipped with drawbar, where the fork stacker consists of two frames, the outer one of which is fixed approximately vertically on the tractor and the other is displaceable in the first by means of a hydraulic cylinder arranged between the frames, and the fork itself is displaceable in the second frame by means of a with one end attached to the fork chain which runs over a guide wheel on top of the second frame and with the other end is attached to the upper part of the first frame so that the fork moves at twice the speed of the second frame, characterized by the towing hooks are attached to the lower end of the second frame. 2. Device according to claim 1, where the tractor's lifting mechanism has vertical arms, characterized in that the free ends of the arms are connected in a manner known per se to the main frame by means of a separate rod, for changing the angle of inclination of the frame. 3. Device according to claim 1, where the tractor's lifting mechanism has horizontal arms, characterized in that the free ends of the arms are connected in a manner known in and of themselves over a separate rod to one end of two angle arms pivotally stored at fixed points on the tractor if other ends above each other rod are connected to the main frame, for changing the angle of inclination of the frame.