Method and catalyst for the dehydrogenation of cyclic secondary alcohols and method for producing this catalyst

 

(57) Abstract:

Describes how dehydrogenation of cyclic secondary alcohols in the presence of a catalyst containing zinc oxide and calcium carbonate, at an elevated temperature in the gas phase, in which the dehydrogenation is carried out in the presence of hydrogen and apply the catalyst, whose active components 30-60 wt.% consist of zinc oxide, and 40-70 wt.% - of calcium carbonate in the modification of calcite. Also describes a dehydrogenation catalyst and process for its production. The technical result - the method allows cyclic ketones, in particular cyclohexanone, to obtain greater selectivity and higher yields and to reduce the formation of the products of the cleavage of the aromatic by-products to a minimum. The proposed catalyst in continuous mode exhibits high strength tablets, especially with regard to the strength of the frontal and lateral compression, so that replacement of the catalyst can be performed much less frequently. 3 S. and 11 C.p. f-crystals, 2 tab.

The invention relates to the dehydrogenation of secondary alcohols, more particularly to a method and catalyst for the dehydrogenation of cyclic secondary alcohols and method of paluh alcohols, which used alcohol digitalout in the appropriate aldehyde or ketone at elevated temperature in the gas phase to the catalyst mainly composed of zinc oxide. The catalyst may contain as copper compounds, and oxides and hydroxides of alkaline earth metals. In the described method during dehydrogenation, i.e. after the beginning of the removal of hydrogen, regulate its flow. In particular, describes the dehydrogenation of cyclohexanol to cyclohexanone, in which the output of cyclohexanone is actually only of 81.5%. Along with 17% of unreacted cyclohexanol, the reaction mixture is from 0.1 to 0.5% of hydrocarbons and 1% of high-boiling condensation products.

In accepted application DE 1,296,625 described a method of producing cyclohexanone from cyclohexanol containing impurities of organic acids and esters, at elevated temperatures in the presence of zinc-containing catalyst consisting of a mixture of zinc oxide - zinc carbonate or mixtures of zinc oxide - zinc carbonate with calcium oxide - calcium carbonate or magnesium oxide - magnesium carbonate.

The disadvantage of this method is a significant reduction in the strength of the tablets in continuous mode is in continuous operation mode is due to the intensive decomposition of carbonates, organic acids or due to phase transformations.

The closest to the invention to the technical essence and the achieved effect is a method of dehydrogenation of secondary alcohols, including cyclic, in particular of cyclohexanol in the presence of a catalyst containing zinc oxide and calcium carbonate, at an elevated temperature in the gas phase (see Chemical Abstracts, vol 121, 22, abstract 258415, 28.11.1994 year).

The objective of the invention is to develop a method by which cyclic ketones, in particular cyclohexanone, can be obtained with greater selectivity and higher outputs, and in which the formation of the products of the cleavage of the aromatic by-products can be minimized. A further objective of the invention is to develop a catalyst in the form of tablets in continuous mode exhibits high strength, especially the strength of the frontal and lateral compression, so that replacement of the catalyst can be less.

The problem is solved in the method of dehydrogenation of cyclic secondary alcohols in the presence of a catalyst containing zinc oxide and calcium carbonate, at an elevated temperature in the gas phase, due to the fact that the dehydrogenation is carried out in PR and 40-70 wt.% - calcium carbonate in the modification of calcite.

A further object of the invention is used in the framework of the proposed method, the catalyst, which is obtained by precipitation of sparingly soluble compounds of zinc and calcium base from solutions of water-soluble compounds of zinc and calcium and the subsequent processing, including drying and calcining, with

(a) as the base used is a water-soluble carbonate basic,

(b) optionally, a sparingly soluble zinc compounds and calcium after deposition of filtered off,

(filtered, if desired, compounds of zinc and calcium washed,

(d) the washed zinc compounds, and calcium (C) is dried to obtain a powder, and then

(d) powder (g) calicivirus at temperatures above 600oAnd

(e) if desired, calcined powder pressed into a molded product.

The method of obtaining the proposed catalyst is another object of the invention.

As the cyclic secondary alcohols can be used, for example, cycloaliphatic alcohols with 5 to 16 carbon atoms, such as Cyclopentanol, cyclohexanol, 4-methylcyclohexanol, cyclooctanol, cyclododecatriene used in the proposed method, the catalyst contains 40-50 wt.% zinc oxide and 50-60 wt.% calcium carbonate in the modification of calcite.

According to another preferred characteristic of the invention, the proposed method is used, the catalyst having a specific surface according to BET of from 5 to 50, preferably from 10 to 30 m2/,

As water-soluble zinc and calcium salts can be used, acetates, sulfates, nitrates, preferably nitrates, such as zinc nitrate, zinc acetate, zinc sulfate, calcium acetate, calcium nitrate, preferably zinc nitrate and calcium nitrate. Usually used aqueous solutions of the respective salts in concentrations in the range from 3 to 25, preferably from 10 to 25, especially 20 wt.%.

The molar ratio of zinc to calcium is chosen so that after calcination the active components of the catalyst 30-60 wt.% consisted of zinc oxide, and 40-70 wt.% - of calcium carbonate in the modification of calcite.

As the base used is a water-soluble basic carbonates, such as carbonates of alkali metals such as sodium carbonate, potassium carbonate, hydrogen carbonates of alkali metals such as sodium bicarbonate, potassium bicarbonate, ammonium carbonate or ammonium bicarbonate, and mixtures thereof, preferably sodium carbonate, particularly preferably in viastore.

The deposition is carried out, in General, at temperatures in the range from 10 to 90oC, preferably from 40 to 80oC. After sedimentation can, if desired, to filter. Filtered, if desired, the precipitate, as a rule, washed with water, preferably until such time as the series of samples for nitrates will not install no, and then dried preferably at a temperature in the range from 90 to 150oWith obtain dried powder. Drying may be carried out in a fixed or movable layer, preferably by sputtering.

The dried powder calicivirus according to the invention at temperatures above 600oWith, preferably in the region from 300 to 600oWith, especially from 400 to 475oWith, preferably in air. In accordance with the existing up to the present time observations over a long heated above 600oWith leads to modification of calcium carbonate in the form of aragonite. In this case, briefly heated above 600oDoes not interfere with the receipt of the catalysts according to the invention as long as it is not formed aragonite (find that by using the method of x-ray diffraction).

After calcination can, dust and so on, preferably tablets.

In one preferred embodiment, the method consisting of calcined powder are pressed together with graphite, preferably from 0.1 to 5, particularly preferably 1-2,5, especially from 2 wt.% graphite, counting on the total weight.

In another preferred embodiment, the method consisting of calcined powder from step (C) (see above) are pressed into molded articles, preferably in a tablet, and thus obtained molded product calicivirus as described for step (g).

Thus obtained whether the powders and molded articles may be used as catalysts, these catalysts as active ingredients include zinc oxide and calcium carbonate (in the modification of calcite), and as a passive component, if desired, graphite.

The catalysts according to the invention have the following physical characteristics.

In another preferred embodiment, the method is used a catalyst of the type according to the invention, which has a pore volume in the region of from 0.10 to 0.50, especially from 0.20 to 0.35 cm2/g, with pore size ranging from 5 nm to 300 μm, and osobine with diameter ranging from 0.01 to 0.5 μm.

Particularly preferred catalysts of the above type are those that possess resistance to failure due to RAM pressure in the range from 500 to 4000 N/cm2primarily from 1000 to 2500 N/cm2and resistance to failure due to lateral pressure from 30 to 300 N, preferably from 50 to 200 N. These values are achieved without calcination. It is important that these resistance bands are observed in production conditions (reaction conditions). However, this only takes place if the process is not accompanied by phase transformation. The method according to the invention ensures compliance with this condition.

Specific surface area by BET is, in General, from 5 to 50 m2/g, preferably from 10 to 30 m2/the Volume of pores with a diameter ranging from 5 nm to 300 μm is typically a value between 0.1 and 0.5 cm3/g, preferably from 2 to 0.35 cm3/g with the proviso that at least 85%, preferably more than 90% of the pore volume accounted for by pores with a diameter ranging from 0.01 to 0.5 μm.

The frontal resistance to the pressure of the tablets is preferably from 500 to 4000 N/cm2especially from 1000 to 2500 N/cm2the resistance of tablets side davenne preferred variant of the method the precipitate of insoluble compounds of zinc and calcium, preferably hydroxycarbonate zinc, and calcium carbonate, washed on filterpress, the obtained residue on the filter is triturated with water and the resulting slurry is spray in the scrubber. Obtained in this way spray dried powder can then be subjected to subsequent processing, as described above.

According to the invention the gaseous secondary cyclic alcohol, preferably cyclohexanol, to which is added from 1 to 20, preferably from 5 to about 10. % hydrogen, considering the amount of alcohol injected into contact with the catalyst itself in the usual way, for example in a reactor with a fixed catalyst bed or reactor with a fluidized bed, preferably in a tubular reactor in which the catalyst is stationary. Unloading is usually carried out by distillation.

In General, you want to use the alcohol is evaporated in itself known manner, for example, in the evaporator, and then the required quantity is mixed with gaseous hydrogen.

The temperature of the gas phase in the reaction zone usually selected in the range from 200 to 500, preferably from 300 to 450oC. In a preferred embodiment, speedmachine from 65 to 75%. When using as a starting compound of cyclohexanol choose a temperature in the range of 350 to 400oC.

The pressure of the gas phase in the reaction zone is chosen, in General, in the region from 80 to 4000, preferably from 100 to 1000 kPa.

The load on the catalyst chosen, in General, in the region of from 0.5 to 3.0, preferably from 0.6 to 2.0 liters of alcohol per liter of catalyst per hour.

In a preferred embodiment, the method of leaving the reaction zone of the reaction mixture to separate the hydrogen and attach it to a mixture of gases supplied to the reaction zone.

Obtained according to the invention ketones, such as cyclohexanone, are important industrial products. For example, cyclohexanone, preferably in the form of the resulting mixture of cyclohexanol, usually then used for the production of adipic acid.

The advantage of the method according to the invention lies in the fact that cyclic ketones, in particular cyclohexanone, can be obtained with higher outputs than it was possible up to the present time, and that in this way the formation of the products of the cleavage of the aromatic by-products is minimized.

Examples

P the we two solutions. Solution 1 is an aqueous solution of zinc nitrate and calcium nitrate with a concentration of 20 wt. %, wherein the molar ratio of zinc : calcium = 1:1,6. Solution 2 is dvuhpolyarnyy aqueous solution of sodium carbonate.

Both solutions are heated to 70oWith and simultaneously pumped by the pump capacity for the deposition. The feed solutions regulate so that during deposition was maintained pH 7,81,0. Formed in such a parallel deposition of the precipitate is filtered and washed with water until no nitrate in the wash water (test with a solution of iron sulfate and concentrated sulfuric acid, the so-called ring nitrate test). Then the residue triturated with water and dried by the method of spray drying. Thus obtained powder is heated in air for 5 hours at 450oFrom and after cooling and addition of 2 wt.% graphite pressed into pills the size of 55 mm Physical characteristics of the catalyst (K10are given in table 1.

Example 2

The dehydrogenation catalyst K10< / BR>
The catalyst K10the number of 920 g, obtained according to example 1, is placed in a tubular reactor with a length of 0.6 mm and the inner is t in the reactor. Before introduction into the reactor add hydrogen at the rate of 7 l/h Temperature of the reaction mixture in the reaction zone support up to 331oC. At this temperature, the conversion is 70%, counting on used cyclohexanol. Leaving the reactor, the reaction mixture was cooled to room temperature with liberation of hydrogen. The liquid reaction products analyzed by gas. At 70% conversion after 1800 hours reach selectivity 99,0% and get the balance 0,70%. The physical characteristics of the catalyst (Kl1800are given in table 1.

Control sample 1

Getting uncalcined catalyst and dehydrogenation with his participation

As described in example 1, an aqueous solution of zinc nitrate and calcium nitrate precipitated calcium carbonate and hydroxycarbonate zinc using dvuhosnogo solution of sodium carbonate. The precipitate is washed until no nitrate and after trituration with water, dried by the method of spray drying. Thus obtained dry powder after adding 2 wt.% graphite pressed into pills the size of 55 mm Catalyst ("K20"), thus obtained, has the physical characteristics shown in table 1. X-ray diffraction analysis the carbonate of zinc. This catalyst in the amount of 920 g was tested at 70% conversion of cyclohexanol as described in example 2. The selectivity of the catalyst after 1800 hours of work is 98.5%, and the resultant residue - 0,88%. The catalyst (K21800has the physical characteristics shown in table 1.

Example 3

Dehydrogenation with KL0(140 hours)

The catalyst (K10) 920, obtained according to example 1, is placed in a tubular reactor with a length of 0.6 mm and an inner diameter of 0.05 m passed Through the evaporator 640 ml/h of liquid cyclohexanol, which is in gaseous form is fed into the reactor. Before introduction into the reactor add hydrogen at the rate of 7 l/h Temperature in the reaction zone support up to 341oC. At this temperature, the conversion is 70%, counting on used cyclohexanol. Leaving the reactor, the reaction mixture was cooled to room temperature with liberation of hydrogen. The liquid reaction products analyzed by gas. At 70% conversion after 140 h achieve selectivity by 98.7% and get the rest of 0.80%. The catalyst (K1140) extract, its physical characteristics are given in table 1.

Test case 2

Digidrirovanny the additional differences namely, that do not use hydrogen, the reaction temperature is 323oWith and the duration of the experiment - 143 hours At 70% conversion selectivity is 96,6%, counting on used cyclohexanol, the rest is 2.37%. The developed catalyst (K2143has physical characteristics, shown in table 1.

The catalyst K10according to the invention in contrast to the non-calcined catalyst K20has a higher resistance as the frontal and lateral pressure. In addition, the resistance to lateral pressure after 1800 hours the catalyst K1 is only reduced by 49% from the original value, while the control catalyst K21800containing aragonite, resistance to lateral pressure drops to one-quarter (26%) of the initial value, when the industrial application means more downtime for replacement organicmaterial catalyst (see table.2).

1. The method of dehydrogenation of cyclic secondary alcohols in the presence of a catalyst containing zinc oxide and calcium carbonate, at an elevated temperature in the gas phase, characterized in that the dehydrogenation is carried out in the presence of hydrogen and Bonita calcium in the modification of calcite.

2. The method according to p. 1, characterized in that as a secondary cyclic alcohol use cyclohexanol.

3. The method according to p. 1 or 2, characterized in that the catalyst has a specific surface according to BET in the range from 5 to 50 m2/,

4. The method according to PP. 1-3, characterized in that the catalyst has a pore volume from 0.1 to 0.5 cm3/g with a pore diameter of from 5 nm to 300 μm.

5. The method according to p. 4, characterized in that at least 85% of the pore volume accounted for by pores with a diameter ranging from 0.01 to 0.5 μm.

6. The catalyst for the dehydrogenation of cyclic secondary alcohols containing zinc oxide and calcium carbonate, characterized in that it contains calcium carbonate in the modification of calcite in the following proportions of active ingredients, wt. %: zinc oxide - 30-60, calcium carbonate in the modification of calcite - 40-70.

7. The catalyst p. 6, characterized in that it has a specific surface according to BET in the range from 5 to 50 m2/,

8. Catalyst under item 6 or 7, characterized in that it has a pore volume of 0.10 to 0.50 cm3/g with a pore diameter of from 5 nm to 300 μm.

9. The catalyst p. 6, 7 or 8, characterized in that at least 8 the texts of the dehydrogenation catalyst according to p. 6 by precipitation of sparingly soluble compounds of zinc and calcium base from solutions of soluble salts of zinc and calcium and the subsequent processing, including drying and calcination, wherein (a) as the base used is a water-soluble carbonate basic, (b), if desired, sparingly soluble zinc compounds and calcium after deposition of filtered (filtered, if desired, compounds of zinc and calcium washed, (d) the washed zinc compounds, and calcium (C) is dried to obtain a powder, and then (d) powder (g) calicivirus at temperatures above 600oAnd (e) optionally calcined powder pressed into a molded product.

11. The method according to p. 10, characterized in that after stage (b) and before stage (g) powder pressed into a molded product, and then calicivirus at temperatures above 600oC.

12. The method according to p. 10, characterized in that the precipitate of insoluble compounds of zinc and calcium is washed on the filter presses, then the resulting washed precipitate triturated with water and the resulting slurry is spray drying in the scrubber, and then the resulting powder is subjected to subsequent processing, as described in the IU tablets he has resistance frontal pressure in the range from 500 to 4000 n/cm2and resistance to lateral pressure in the range from 30 to 300 ad

14. The catalyst p. 13, characterized in that the method of diffraction of x-rays can confirm the presence of only calcite and zinc oxide.

 

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