RU2064830C1 - Method of copper-bearing catalyst preparation for liquid phase dehydrogenation of alcohols - Google Patents

Abstract

FIELD: processes of liquid phase dehydrogenation of mono- and multiatomic alcohols of aliphatic and alicyclic rows. SUBSTANCE: Catalyst is produced using treatment of water complex solution of copper with solution of boric hydrate of sodium or potassium in ratio of 2 moles of boric hydride per 1 mole of copper. EFFECT: duration of effective action of catalyst is increased ten times as much. 4 tbl

Description

 The invention relates to the production of a catalyst containing copper, which can be used in liquid phase dehydrogenation processes of monohydric and polyhydric alcohols of aliphatic and alicyclic series.

 A known method of producing a catalyst containing copper, intended for liquid-phase dehydrogenation of dialkylene glycols / Pat. USA N 2 807 629, 1957 /, which we adopted as a prototype.

 The catalyst is prepared as follows.

An aqueous solution containing ammonium dichromate and ammonium hydroxide is mixed with an aqueous solution of copper nitrate in a ratio of 1 mol of copper per 0.5 mol of ammonium dichromate. The precipitated copper chromate precipitate is separated and dried until moisture is completely removed. Dry copper chromate is heated to 350-500 ^o C, the resulting mixture of copper chromite and copper oxide obtained by heat treatment is crushed and treated with an aqueous solution of acetic acid, washed and dried.

The catalyst is a dispersed powder containing copper and chromium. To carry out the liquid phase dehydrogenation process, the catalyst is suspended in dialkylene glycol and the mixture is heated to boiling at atmospheric pressure. The operating temperature of the process is 240-280 ^o C.

 The most effective copper-chromium catalyst for liquid-phase dehydrogenation of diethylene glycol.

The disadvantages of the copper-chromium catalyst are:
1. Limited time efficient operation of the catalyst.

 2. The multi-stage process of preparation, including at least ten operations.

3. The need for special equipment for grinding and heating up to 500 ^o C.

 4. Disposal of spent catalyst requires special technology to separate copper from chromium.

 The objective of the invention is to obtain a catalyst containing copper for the liquid phase dehydrogenation of monohydric and polyhydric alcohols of aliphatic and alicyclic series, which has a long effective time.

 The problem is solved by a method for producing a catalyst containing copper for liquid-phase dehydrogenation of alcohols, in which an aqueous complex solution of copper is treated with a solution of sodium or potassium borohydride in the ratio of 2 mol of borohydride per 1 mol of copper. The precipitate formed is separated, washed and dried.

 Obtained by the proposed method, the catalyst in the reactions of liquid-phase dehydrogenation of monohydroxy and polyhydric aliphatic alcohols has an effective time of 10 times longer compared to the prototype.

 The method is illustrated by the following examples.

 Example 1

 In a 1.5-liter reaction vessel equipped with a magnetic stirrer, 1.0 L of an ammonia solution of copper containing 50 g (0.2 mol) of copper pentahydrate and 80 ml of 25% aqueous ammonia is placed; 15.2 g (0.4 mol) of sodium borohydride are dissolved in 100 ml of distilled water, the resulting solution is added to an ammonia solution of copper with continuous stirring.

The precipitate is separated on the filter, washed and dried in air at 100-110 ^o C.

 The final product in an amount of 12.45 g (98.5% copper yield) is a loose powder, stable in air.

 Examples 2, 3 differ in that the catalyst is obtained from tartrate and trilonate solutions of copper, the data are shown in table 1.

 Similar results were obtained using potassium borohydride. The data are shown in table 2 (examples 4-6).

 Obtained by the proposed method, the catalysts were tested in the processes of liquid phase dehydrogenation of diethylene glycol, 1,4-butanediol, nonanol-1 and cyclohexanol.

 The dehydrogenation process is carried out according to the following scheme: alcohol and a catalyst are charged into a reaction vessel connected to a distillation column, the mixture is heated to boiling at atmospheric pressure, while the liquid reaction products are continuously distilled off.

Example 7
106 g of diethylene glycol and 1.5 g of the catalyst obtained by the proposed method from an ammonia solution of copper under the action of sodium borohydride, are loaded into a 250 ml reactor. The reactor is connected to a distillation column, which in turn is connected to a water cooler.

 The mixture is heated to boiling at atmospheric pressure, the dehydrogenation product of 2-para-dioxanone is continuously removed from the reactor. In 225 minutes, 85.43 g of distillate was obtained containing 96% by weight of 2-para-dioxanone, which is 82% of the theoretical yield.

The temperature of the reaction mixture at the beginning of the process is 240 ^{o C.} , at the end - 260 ^o C.

 Examples 8, 9, 10, characterized in that 1,4-butanediol, nonanol-1 and cyclohexanol were dehydrogenated are shown in table 3.

 Similar results were obtained using a catalyst obtained by the present method from tartrate and trilonate solutions of copper using sodium borohydride, from ammonia, tartrate, trilonate solutions using potassium borohydride.

 Data on the time of effective operation of the catalyst was obtained for the liquid phase dehydrogenation of diethylene glycol in a batch reactor. Catalyst run time net dehydrogenation time, excluding auxiliary operations. The results are shown in table 4.

 The data show that the inventive catalyst can be used in the processes of liquid phase dehydrogenation of alcohols. The effective working time of the catalyst is more than ten times the effective working time of the copper-chromium catalyst.

Claims (1)

 A method of preparing a copper-containing catalyst for liquid phase dehydrogenation of alcohols, including precipitation from an aqueous solution and drying, characterized in that the precipitation is carried out from an aqueous complex solution of copper with a solution of sodium or potassium borohydride in a ratio of 2 mol of borohydride per 1 mol of copper.

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