The method of obtaining lower ketones

 

(57) Abstract:

The invention relates to the production of lower ketones liquid-phase dehydrogenation of secondary alcohols in the presence of a fixed catalyst - Nickel metal or activated hydrogen Nickel metal or Nickel on the carrier in the environment paraffins C12-C20that process is used as solvent, the drying means, the environment for the activation of the catalyst and carrier. The flow of the lower alcohol is directed countercurrent or co-current to the stream of paraffins fed to the reactor from the top layer or underneath a layer of catalyst. The method allows to reduce energy consumption, the consumption of reagents to increase the yield of the target product to 99.8%, to simplify the technology. 2 C. p. F.-ly, 3 ill., table 2.

The invention relates to the petrochemical industry, and more specifically, to a method for producing lower ketones.

Lower ketones (acetone, methyl ethyl ketone, and other widely used as solvents in industry varnishes and paints, as well as intermediates in the synthesis of various monomers.

A method of obtaining lower ketones gas-phase dehydrogenation of a secondary alcohol at 350-400Syria with low selectivity to ketone, a significant amount of side products and, consequently, high cost of production not only because of the high expenditure coefficients on secondary alcohol, but also because of the additional costs of treatment of target products.

There are also known methods of obtaining lower ketones liquid-phase catalytic dehydrogenation of a secondary alcohol, for example, in the presence of a suspension of Nickel Raney in butter or oil at a temperature of 160-190oC (patent application Japan N 60-258135).

At higher temperatures (up to 230oC) carry out the dehydrogenation of a secondary alcohol in the presence of finely dispersed suspension of Nickel Raney in paraffin hydrocarbons (Europatent N 43309). The method described in journal of the Hydrocarbon Proc., Nov. 5 , 1979 p. 182.

The preparation of such a catalyst requires fine grinding, that in his proforest and well-developed surface creates certain difficulties in the stages of loading and unloading, as well as the separation of spent catalyst from the solvent. This is especially dangerous when the leaching alloy Renee and dehydrogenation operations associated with the need to ensure high speed stirring in the reaction medium, emitting hydrogen. Sotdae invention was the creation of high-tech, safer and more efficient processes that reduce consumption of reagents, catalyst and energy.

It was found that the task, in accordance with the present invention, is solved by the method of obtaining lower ketones by liquid-phase dehydrogenation of the corresponding secondary alcohol in the presence of Nickel catalyst at elevated temperature and pressure in the environment paraffins C12-C20as a solvent, characterized in that the starting secondary alcohol dehydrate paraffin C12-C20share on raffinato water and extract the organic phase, the latter is subjected to distillation to remove the azeotrope of the alcohol-water, drained the alcohol is vaporized and injected into a flow dehydrogenation reactor filled with a fixed catalyst bed, the catalyst bed counter - or co-current to the solvent circulating through the catalyst comprising a granular metallic Nickel or pre-activated with hydrogen in the environment paraffins Nickel metal or Nickel on a carrier, or drained the alcohol is sent to the reactor between the layers of the catalyst, where it digitalout not reacted with the tall or Nickel on a carrier activate hydrogen, exhaust from the stage dehydrogenation submitted directly - or countercurrent to the circulating paraffins C12-C20and the lower dehydrogenation of secondary alcohols is carried out at a temperature of 130-170oC.

For a better understanding of the invention and Fig. 1, 2 and 3 the technological scheme of obtaining lower ketones by dehydrogenation of secondary alcohols.

In Fig. 1 shows a variant of the technological design process for the dehydrogenation of a secondary alcohol to the ketone, in which the mixer 1 of the original alcohol mixed with paraffin in a ratio shown in table. 1. The resulting mixture is separated in a settling tank 2 on raffinato (aqueous) and extract (organic) phase, the latter is subjected to azeotropic distillation for separation of residual water in the form of an azeotrope of the alcohol-water distillation column 3. CBM product, representing a solution of the alcohol waxes are sent forth into the evaporator column type 4. A pair of nearly anhydrous alcohol is introduced into the reactor column type 5, comprising a reactor and a distillation section, under the fixed layer of the catalyst. CBM product of the evaporator 4 - paraffins, return to the stage of dehydration in the mixer 1. The temperature in the reactor dehydrin is served with a co-current with alcohol vapor. The products of the dehydrogenation away from the reactor 5 at the top. After separation of the ketone hydrogen is directed to the activation of the catalyst is carried out in the same reactor operating alternately with the first, i.e. in each reactor spend the first activation of the catalyst, and then the dehydrogenation of the alcohol.

In Fig. 2 shows a variant of the technological scheme of the process in which the wax is fed into the reactor at the layer of catalyst countercurrent to the secondary alcohol, imposed under the layer of catalyst. In the rest of the diagram is similar to Fig. 1.

In Fig. 3 drained the alcohol from the column 3, together with the paraffins in the liquid phase is injected between the layers of catalyst in the reactor 5, the temperature of the dehydrogenation process in which support the circulation part of the paraffins from the cube reactor at its upper reactor portion of the pump 6 through the heater 7. Another part of paraffins return to the mixer for dehydration of alcohol. Unreacted alcohol with a ketone is introduced into the middle part of the distillation section of the reactor 5, where the condensed alcohol is sent to the evaporator 4. From the evaporator 4 alcohol vapor return in the cubic part of the reactor 5 under a layer of catalyst, where completed his digid, where instead of the commonly used dehydrating agents azeotropically requiring subsequent separation with alcohol, are paraffins, in an environment which then undergoes dehydration. In addition, as has been established, subsequent dehydration dehydrated alcohol by azeotropic distillation, the residual water is much easier in the presence of paraffins, and the azeotrope of the alcohol-water is separated from a mixture of ethanol-paraffin, and not from alcohol.

Use in dehydrated paraffins and dried by azeotropic distillation of alcohol, along with other techniques used, allows almost completely to degidrirovanii alcohol in more mild conditions with high conversion and selectivity. It is established that dehydration dehydrated, but not drained of alcohol significantly reduces the reaction rate, with a corresponding reduction of the yield of the target products.

At the stage of dehydrogenation of the alcohol introduction alcohol right - or counter-current to circulate through the catalyst paraffins greatly facilitates application of heat to the catalyst particles. As was found, it creates the conditions under which the catalyst particles covered with a thin layer of paraffin, which significantly UAZ.

Preliminary evaporation of the alcohol before putting it into the reactor enables you to evenly distribute and organize almost uniform temperature throughout the catalyst bed to maintain the optimum circulation rate paraffins, providing favorable for the process of dehydrogenation hydrodynamic regime.

Activation of the catalyst in the environment paraffins in addition to the technological advantages (no distillation of the solvent after dehydrogenation) can significantly reduce the activation temperature and the feed rate of hydrogen. The consequence of this is the use of hydrogen discharged from the stage of dehydrogenation. In contrast, the activation of the catalyst in the absence of paraffin ceteris paribus is not possible to obtain an active catalyst. The dehydrogenation in the presence of such a catalyst is hardly taking place.

Thus, the present invention enables to simplify the process, reduce energy and material costs and to ensure high yields of the target products in more mild conditions than in the method prototype. The consequence is a significant increase in service life of the catalyst and installation in clausii it.

Examples 1-10. In examples 1-3 describe the preparation and activation of catalysts for the dehydrogenation of secondary alcohols, 4-6 - preparation of secondary alcohols by dehydration (table. 1); in the examples 4-17 summarizes the conditions of implementation and the results of the dehydrogenation of secondary alcohols (table. 2).

Example 1. The alloy of Nickel and aluminum with a particle size of 3-10 mm load on the distribution grid at the bottom of the reactor 5, a reactive distillation apparatus with a diameter of 100 mm Aluminum leached with an aqueous solution of alkali and washed off the excess alkali with water. Then pump 6 was charged to the reactor a mixture of paraffins, which through the heater 7 to circulate the steaming water from the catalyst. After the stage of bog water, the catalyst is ready for use.

Example 2. Nickel on kieselguhr as tablets of 5 mm diameter and 5 mm thick loads in the lower part of the reactor 5 on distributive lattices with several layers (see tab. 1). There also is served heated in the heater 7 paraffins and hydrogen discharged from the stage dehydrogenation, before the termination of the allocation of water, after which the catalyst is ready for use.

Example 3. Nickel-chromium catalyst is prepared from tablets is th butyl alcohol (VBS) with a concentration of 72 wt.% mix in the mixer 1 with a stream of paraffins, coming from the evaporator 4, and injected into the tank 2 for phase separation. Rafinate phase are sent to concentration by distillation for separation of the azeotrope WBS water with alcohol content of 72 wt.%. The extract phase is fed to the dehydration column 3. From the top of column 3 assign azeotrope VBS-water, which is directed to the extraction in mixer 1 (Fig. 1). From the cube column 3 of dewatered mixture of ethanol and paraffin is sent to the evaporator 4. There also introduce returnable alcohol from the reactor 5. From the evaporator 4 alcohol vapor is directed into the lower part of the reactor 5. Out of the heater 7 is heated paraffin served under a bed of the catalyst of example 1. From the top of reactor 5 select the methyl ethyl ketone (MEK) and hydrogen. The results are presented in table. 1 and 2.

Example 5. The process is carried out in accordance with example 4, as a secondary alcohol use isopropyl alcohol (IPA), with acetone. The results are shown in table. 1 and 2.

Example 6. Dehydration VBS carried out in accordance with example 4, and the dehydrogenation in the presence of the catalyst of example 1, the circulation paraffins carried out from top to bottom (Fig. 2). The results are shown in table. 1 and 2.

Example 7. The process is carried out in accordance with example 6, with ispolzovaniem in accordance with example 6, using a Nickel-chromium catalyst according to example 3. The results are shown in table. 1 and 2.

Example 9. In the mixer 1 mix VBS with a concentration of 72 wt.% with waxes, coming from the reactor 5, and return the azeotrope VBS-water. The resulting mixture rasclaat in the sump 2. Rafinate phase are sent to concentration by distillation to separate the azeotrope WBS water with alcohol content of 72 wt.%

The extract phase is introduced into the dehydration column 3, from the top of which are selected azeotrope VBS-water which is sent further to the dehydration in the mixer 1.

From the cube column 3 of the drained mixture of alcohol and paraffin served in the reactor 5 between the layers of Nickel-chromium catalyst prepared according to example 3. Recurrent alcohol through the evaporator 4 is introduced into the lower part of the reactor 5 under a layer of catalyst, and the top layer of the catalyst serves heated in the heater 7 paraffins. The reaction products Mack and the hydrogen away from the top of reactor 5. The results are shown in table. 1 and 2.

Compared with the method of the prototype using the present invention (known data) saves 0,5 tons of vapor and 15 m3water for each ton of ketone.

Thus, as can be seen the selectivity of the target product, hydrogen is a by - product stage dehydrogenation to activate the catalyst, and the activation is carried out in a sealed reactor. Eliminated the need to separate the secondary alcohol from dehydrating agent, because he is both a solvent in the process of dehydrogenation of the alcohol. And besides, the main quantity of water from the azeotrope of the alcohol-water is separated by mixing it with paraffin, so there is no stage of evaporation of water and significantly reduced power consumption at the stage of dehydration of alcohol. All of the above allows us to consider the method according to the present invention, high-tech, more fire-safe and economical. Process without significant capital investment can be used on almost any petrochemical production.

1. The method of obtaining lower ketones by liquid-phase dehydrogenation of the corresponding secondary alcohol in the presence of Nickel catalyst at elevated temperature and pressure in the environment paraffins C12- C20as a solvent, characterized in that the starting secondary alcohol dehydrate paraffin C12- C20the mixture is divided into raffinato water and extract the keys and injected into the flow reactor dehydrogenation, filled fixed bed of catalyst under a layer of catalyst counter - or co-current to the solvent circulating through the catalyst comprising a granular Nickel metal or pre-activated with hydrogen in the environment paraffins Nickel metal or Nickel on a carrier, or drained the alcohol together with the paraffins are sent into the reactor between the layers of the catalyst, where it digitalout, unreacted alcohol is evaporated and the vapor returns to the reactor below the catalyst bed.

2. The method according to p. 1, characterized in that the dehydrogenation catalyst is a Nickel metal or Nickel on the carrier to activate the hydrogen discharged from the stage dehydrogenation submitted directly - or countercurrent to the circulating paraffins C12- C20.

3. The method according to p. 1, characterized in that the dehydration of the lower alcohol is carried out at 130 - 170oC.

 

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