Issue 14/2012 - Advances in Methyl Ethyl Ketone Production Technology

Methyl ethyl ketone is an organic solvent with excellent performance and wide application, with excellent solubility and drying characteristics, and has the advantages of high boiling point and low vapor pressure, and has good solubility properties
for various natural resins, cellulose esters, synthetic resins, etc.
In addition, methyl ethyl ketone can also be used in the production of methyl ethyl peroxide, methyl allyl ketone, methyl amyl ketone and methyl ionone and other chemical products
.

At present, the production methods of methyl ethyl ketone mainly include n-butene method, butane liquid phase oxidation method, butadiene catalytic hydrolysis method, butene liquid phase oxidation method, isobutylbenzene method, isobutyraldehyde isomerization method and fermentation method
.
Among them, the industrial production methods mainly include n-butene method, butane liquid phase oxidation method and isobutylbenzene method
.

First, n-butene method 1.
one-step oxidation method n-butene one-step oxidation method to produce methyl ethyl ketone using palladium chloride/chlorinated ketone oxidation-reduction homogeneous catalyst system, the production process of this method

is simple, but because the catalyst contains chlorine, there are strong corrosiveness, many by-product chlorides, complex separation process and other shortcomings
.
In view of the shortcomings of this method, a homogeneous process using composite catalysts and a multiphase fixed bed process
have been developed.
For example, the new heteropoly acid homogeneous catalytic oxidation process developed by Catalytic Associates adopts a chlorine-free catalyst system, which contains Pd2+, Cu2+ and heteropolyacid oxygen anions, and adds nitrile coordination to improve selectivity and conversion, and the reaction is carried out at 85 °C and 0.
7MPa, and the selectivity of methyl ethyl ketone can reach 90.
3%.


2.
Two-step oxidation method
n-butylene two-step oxidation method is to hydrate n-butylene to obtain sec-butanol, and then dehydrogenation to generate methyl ethyl ketone
.
This method is currently the most important method for the production of methyl ethyl ketone in the world, including two reaction steps
of n-butylene hydration to sec-butanol and dehydrogenation of sec-butanol to methyl ethyl ketone.

(1) n-butylene hydration to sec-butanol At present, the methods of n-butylene hydration to sec-butanol
in industry mainly include indirect water method with sulfuric acid as catalyst, direct water method with ion exchange resin as catalyst, and direct water method with heteropoly acid as catalyst
.

Sulfuric acid indirect hydration process It includes 4 main processes
such as esterification, hydrolysis, rectification and dilute acid concentration.
The mixed C4 fraction containing mainly n-butene absorbed by sulfuric acid with a concentration of about 80% was used to react to generate butyl sulfate; Butyl sulfate is hydrolyzed to obtain an aqueous solution of sec-butanol, and then rectified to obtain sec-butanol
.
The production process of this method produces a large amount of dilute acid, the equipment corrosion is serious, the treatment of three wastes is more complicated, the energy consumption is high, and it is gradually being eliminated
.

Resin direct hydration process This method was successfully developed by Deutsche Texco in Germany in 1984 and is currently the most important method
for producing sec-butanol at home and abroad.
The method uses resin as catalyst, n-butylene generates sec-butanol through proton catalysis, the reaction is carried out under three-phase conditions, the reaction temperature is 150~170 °C, the reaction pressure is 5.
0~7.
0MPa, the molar ratio of water and n-butylene is about 1:1, and the resin is mostly selected with strong acid cation exchange resin
with good heat resistance.
The process flow of this method is simple, the product recovery and refining is easy, the three wastes are less, the corrosion to the equipment is small, the secondary butanol has high selectivity, the disadvantage is that the raw material n-butylene is required to be higher, and the content of n-butene in the C4 fraction is generally required to be higher than 90%.

In addition, the resin catalyst has poor high temperature resistance, short life, easy inactivation, and low single-pass conversion rate of n-butylene (not higher than 10%)
.

Heteropoly acid direct hydration process This method was successfully
developed by Idemitsu Kosan Corporation in 1985.
Sec-butanol
is prepared by direct hydration of n-butene under the action of heteropoly acid catalyst.
The main component of the heteropoly acid catalyst is molybdenum phosphoric acid, and organometallic compound additives
are added.
The reaction temperature is 200~230 °C, the reaction pressure is about 19.
0MPa, and the selectivity of sec-butanol is greater than 99%.

In this reaction, n-butene is both a reactant and a supercritical extractant for the product
, sec-butanol.
The process flow of this method is simple, the catalyst performance is stable, the life is long, the reactor efficiency is high, the by-products of high boiling point are not accumulated in the reactor, and the disadvantage is that the single-pass conversion rate of n-butylene is low, and the reaction needs to be carried out
at high pressure and higher temperature.

(2) sec-butanol dehydrogenation to methyl ethyl ketone secbutanol dehydrogenation to methyl ethyl ketone
can be divided into two processes
: gas phase dehydrogenation and liquid phase dehydrogenation.
Gas phase dehydrogenation is currently a common method
in industry.
Using zinc oxide or zinc-copper alloy as catalyst, sec-butanol is heated and gasified, and the dehydrogenation reaction is carried out in the dehydrogenation reactor at 355~375 °C and 0.
34MPa pressure, and the reaction product is separated by condensation to obtain methyl ethyl ketone, and the conversion rate of sec-butanol and the selectivity of methyl ethyl ketone are above
90%.
The disadvantage is that the purity of the product is lower and the catalyst life is shorter
.

The liquid phase dehydrogenation of sec-butanol uses skeleton nickel or ketone chromate as catalyst, the reaction temperature is controlled at 150~200 °C, and the single-pass conversion rate of sec-butanol is low under atmospheric pressure, but the selectivity of methyl ethyl ketone is above
99%.
The method has the advantages of simple process flow, long catalyst life, simple product separation, low energy consumption and high yield, but the disadvantage is that the single-pass conversion rate of sec-butanol is lower than that of the gas phase method
.

Fang Deren et al.
of Yantai University developed a catalyst for the dehydrogenation of sec-butanol to prepare methyl ethyl ketone and a preparation method
.
The method uses CuO, ZnO, ZrO2, and Al2O3 as the main active components, and M2O as the catalyst modifier
.
The preparation method of the catalyst is: the soluble salts of copper, the soluble salts of zinc, the soluble salts of zirconium and the soluble salts of aluminum are miscible in deionized water, and then the alkali solution is added for co-precipitation, and the precipitation is completed, the precipitation mixture is washed and dried with water, and the modifier or modifier raw materials are added to mix evenly, roasted, and tableted
.
The catalyst not only greatly improves the conversion of sec-butanol, but also significantly improves the selectivity
of methyl ethyl ketone.

Second, butane liquid phase oxidation method
The main product of butane liquid phase oxidation method is acetic acid, and methyl ethyl ketone is a by-product (accounting for about 16% of acetic acid production).

The United Carbonization Company and the Celanese Company both use this method to produce methyl ethyl ketone
.
The process is gas-liquid phase reaction, the catalyst is cobalt acetate-sodium acetate, the solvent is acetic acid, the reaction temperature is 160~165 °C, the pressure is 5.
6MPa, the mass ratio of methyl ethyl ketone and acetic acid is about 0.
4:1, and the by-products are mainly ethyl acetate, propionic acid, acetaldehyde, etc
.
The disadvantage of this method is that the product recovery and separation system is complex, the investment is high and the energy consumption is large, and it is being gradually eliminated
.

Third, the isobutylbenzene method
uses aluminum chloride as the catalyst, the reaction temperature is controlled at 50~70 °C, and n-butylene and benzene are reacted by alkylation to generate isobutylbenzene; Isobutylbenzene oxidizes in liquid phase to generate isobutylbenzene hydrogen peroxide under pressure of 110~130 °C and 0.
1~0.
49MPa; Then decompose in the presence of acid catalyst, concentrate the oxidation solution at 20~60 °C to generate methyl ethyl ketone and phenol; Finally, the refined product
is separated.
Under normal circumstances, per 1t of methyl ethyl ketone can be co-produced 1.
26 ~ 1.
28t phenol, by-product 0.
2 ~ 0.
26t acetophenone, butene utilization rate of 67% ~ 70%, the method is characterized by mild reaction conditions, light equipment corrosion, conducive to industrial production, but the process is more complicated, strict operating conditions
.

Fourth, the fermentation method
is to prepare glucose by double enzymatic method using corn and other starch as raw materials, prepare 2,3-butanediol by biological fermentation, and then prepare methyl ethyl ketone
by sulfuric acid catalytic dehydration.
The former has a glucose conversion rate of more than 90%, the latter 2,3-butanediol conversion rate is close to 100%, and the yield of methyl ethyl ketone is about 95%.

The process flow of this method is simple, the reaction conditions are mild, the reaction is rapid, the substrate conversion rate and product yield are high, and there is basically no environmental pollution
.
Although the current production cost is still difficult to compete with petrochemical synthesis methods, in the future of increasingly tight resources, biosynthetic methyl ethyl ketone will open up a new raw material route
for the production of methyl ethyl ketone.

Zhang Jian'an et al.
of Tsinghua University developed a method
for the efficient dehydration of 2,3-butanediol to produce methyl ethyl ketone.
Under the action of zeolite type solid acid catalyst, 2,3-butanediol is dehydrated to prepare methyl ethyl ketone
.
With 10%~90%(wt)2,3-butanediol solution as raw material, preheated gasification at a reaction temperature of 200~300 °C, the gasified raw gas is reacted through the catalyst layer, the mass airspeed of 2,3-butanediol is 1.
5~3.
4h-1, and the reactor outlet material is separated by gas and liquid to obtain methyl ethyl ketone
.

Huang He of Nanjing University of Technology and others invented a method
for preparing methyl ethyl ketone.
This method uses ZSM-5 or NaY zeolite catalyst to catalyze the preparation of methyl ethyl ketone
by dehydration of 2,3-butanediol.
The catalyst is not easy to be inactivated, has good stability, high substrate conversion rate and product yield, low environmental pollution, the conversion rate of 2,3-butanediol can reach 90.
5%~100%, and the selectivity of methyl ethyl ketone can reach 83.
7%~91.
3%.

5.
Butadiene catalytic hydrolysis American
Shell has developed a new process for the preparation of methyl ethyl ketone, using 1,3-butadiene as raw material, using a composite catalyst, and directly reacting
in the presence of water and solvent.
The catalysts used are ruthenium, rhodium, iridium and other group VIII metal oxides, carboxylate and organic acid proton sources and a ligand; The solvent is decane and other hydrocarbon solvents and some polar solvents, the reaction is carried out at 100~170 °C, and the methyl ethyl ketone obtained after separation and refining has a maximum yield of 85%.

6.
Mixed C4 hydrocarbon oxidation method
American Shell Company uses C4 mixture as raw material for methyl ethyl ketone synthesis research, with cobalt, rhodium, palladium and other metals contained in γ-alumina or MgAl2O4 spinel as catalyst, the reaction temperature is 250~350 °C, the pressure is 0.
5~10MPa, and the highest yield of methyl ethyl ketone is 11%.

7.
Isobutylene oxidation method
Phillips Petroleum Company developed isobutylene oxidation process with free oxygen, surfactant, copper, palladium chloride and other metal chlorides as catalysts, and in the presence of diluent reaction, the reaction product in the tert-butanol can be separated as a solvent or dehydrated into isobutylene for recycling
.
The oxidation reaction temperature is 60~150 °C, the pressure is 0.
54~0.
82MPa, and the reaction can be separated and recovered by extraction and distillation
.
The advantages of this method are that the process is simple, the by-product tert-butanol can be reused, the disadvantage is that the reactor and pipeline need to be lined with glass tantalum or titanium materials, the equipment investment is large, and the yield of methyl ethyl ketone is low (less than 50%)
.

Although a variety of new methyl ethyl ketone production process technologies have been developed in recent years, the industry will still be dominated by the two-step oxidation process of n-butylene, and the progress of technology is mainly reflected in
the improvement and improvement of catalysts and production processes.