JPS604139A - Selective hydrogenation process - Google Patents

Abstract

PURPOSE:To carry out the selective hydrogenation of an acetylene compound and phenylacetylene in styrene, in liquid phase under atmospheric or pressurized condition, by using a catalyst containing palladium and a VIB-group metal or its salt and supported on alumina. CONSTITUTION:Acetylene compounds and phenylacetylene existing as impurities in styrene useful as a raw material of plastics and other chemicals are selectively hydrogenated in liquid phase under atmospheric or pressurized condition, and removed. The selective hydrogenation of the impurities can be promoted, and the removal ratio can be increased by carrying out the reaction in the presence of a catalyst containing palladium and a IVB-metal or its salt (e.g. tin, lead or nitrage, acetate, etc. containing said metals as cation) and supported on alumina. In addition to the above effects, the hydrogenation of styrene can be suppressed and the loss of styrene caused by the side reaction can be minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for selectively hydrogenating phenylacetylene, an acetylene compound in styrene containing 1q, under normal pressure or pressurized liquid phase conditions by dehydrogenation of ethylbenzene, etc. In particular, the present invention relates to a method characterized in that a catalyst containing palladium supported on alumina and a metal of the RVBM group of the periodic table or a salt thereof is used as a catalyst.

Sutylene, which is important as a raw material for the chemical industry, is produced from 1-tyrene and benzene] and is produced industrially by dehydrogenation of ethylbenzene or by a co-production method with propylene A-kylide known as the A-xylan method. The production of styrene by the dehydrogenation method of ethylbenzene is carried out at a high temperature of 600°C or higher in the presence of water vapor, and the catalyst used at this time is, for example, ZnO-CaO-K20-AfJ, 20
The latter three series are used industrially.

In recent years, there has been remarkable progress in improving catalysts, and catalysts with extremely high -C selectivity for styrene have been developed. However, in the case of high-performance catalysts with high styrene selectivity, the hydrogen temperature needs to be higher than before, so acetylene compounds, which have traditionally not caused problems, are added to the styrene produced. ,
A situation has arisen in which Diren is produced as a by-product of Fenirua.

When using this styrene as raw material for plastic snacks and other chemical industries, it is necessary to treat it in advance to keep the temperature below a certain level, as the phenylacetylene contained therein is a major hindrance. It must be a5 except for.

It is possible to remove phenylacetylene from styrene by ordinary distillation, but separation by distillation is difficult because the boiling points are close to each other. Furthermore, as a method for removing phenylacetylene from styrene, a method of selectively hydrogenating phenylacetylene under gas phase or liquid phase conditions F in the presence of a catalyst has also been attempted. However, in this method, hydrogenation of styrene is difficult because there is little difference in reactivity between styrene and the impurity phenylacetylene, and the concentration of phenylacetylene to be hydrogenated is extremely low compared to the styrene concentration. It is extremely difficult to selectively and sufficiently hydrogenate only phenylacetylene while suppressing phenylacetylene as much as possible.

The gas phase method is disadvantageous because the catalyst deteriorates quickly and is extremely energy-consuming, whereas the liquid phase method has fewer drawbacks such as catalyst deterioration because the reaction is carried out at a relatively low temperature, but on the other hand, hydrogenation of phenylacetylene In order to achieve this almost completely, it is necessary to use a considerably large amount of hydrogen, which inevitably leads to the problem that the proportion of hydrogenation of styrene increases.

In view of the current situation, the present inventors conducted various investigations in order to develop an effective catalyst for selectively hydrogenating the acetylene compound in styrene, phenylacetylene, and as a result, palladium and The present inventors have discovered that a catalyst in which a 1Vb group metal or its salt is supported on alumina has excellent performance, and has completed the method of the present invention.

That is, the present invention relates to a method for selectively hydrogenating an acetylene compound, phenylacetylene, in styrene under normal pressure or pressurized liquid phase conditions, using palladium supported on alumina as a catalyst and the first V of the periodic table. It is an object of the present invention to provide a method characterized by using a catalyst containing a group B metal or a salt thereof.

The method of the present invention will be explained in more detail below.

The catalyst used in the method of the present invention has the formula Pd-X-AJL203 (X is a metal of group 1Vb of the periodic table or its salts) 'C''. Please give a specific example of X. Examples include tin, lead, and nitrates and acetates that convert these into cations.

Various metal oxides can be used as the catalyst carrier, but alumina is particularly preferred, and γ-A 203
．． η-A sentence 203, θ-A sentence 203, etc. are suitable. As for the catalyst composition, the ratio of palladium to the carrier is 0.01 to 5% by weight, preferably 0.03 to 2% by weight, and
The ratio is in the range of 0.1 to 10, preferably 0.5 to 8 as an atomic ratio (X/Pd). There are no particular restrictions on the method for preparing the catalyst, and methods commonly used for this type of catalyst may be used as appropriate.

For example, the temperature can be adjusted as follows.

After impregnating an alumina carrier with a predetermined amount of a solution of acid or water-soluble salts such as palladium chloride, palladium nitrate, palladium acetate, and sodium palladium chloride, the palladium salt is mixed with hydrogen, hydrazine, formaldehyde, sodium formate, and sodium borohydride. It is reduced to metallic palladium by a dry or wet method using a suitable reducing agent such as hydride. Next, the alumina carrying metallic palladium is thoroughly washed with water and dried (4).

Next, this is immersed in a solution in which soluble salts such as tin and lead are dissolved at a predetermined concentration so that the salts of tin and lead are supported and zeolized, subjected to reduction treatment if necessary, and dried to obtain the desired catalyst.

There are no strict limitations on the reaction conditions when carrying out the method of the present invention, but the reaction is generally carried out under the following conditions.

The reaction temperature is in the range of 0 to 80°C, preferably 5 to 60°C, the reaction force is 1:1 pressure to 20kg/cm2G, preferably 1 to 10k(+/am2G, I-12 and phenyla are moles of dylene). The ratio is from 0.1 to 15, preferably from 1 to
The range of 10, ml-ISV depends on the reaction temperature, reaction pressure, phenylacetylene concentration and degree of its hydrogenation removal, but the range is 2.
~80 h r-1, preferably 4-40 t+
They are respectively set in the range r-1.

1 (2) used in the present invention may be pure or may be diluted with an inert gas such as methane.

The content of phenylacetylene in the styrene used in the method of the present invention is not particularly limited, but is 0.001 to 2.
Hydrogenation removal is possible within a range of wt%.

The reaction type in carrying out the method of the present invention is a fixed bed reaction, and either a flowing type or a vortex type can be adopted to carry out a fixed bed reaction in a liquid phase. 7 Furthermore, as the reactor, either an isothermal type or an adiabatic type can be used.

In the method of the present invention, selective hydrogenation is promoted, the removal rate of phenylacetylene is very high, and the hydrogenation of styrene caused by side reactions is significantly reduced, so the loss of styrene is minimized. It has the great advantage of being able to

Hereinafter, the method of the present invention will be explained in more detail by showing typical examples. However, these are merely examples, and it goes without saying that the present invention is not limited thereto.

Example 1゜(1) Raw material composition Styrene 99.5wt% Phenylacetylene 0.5 (2) Hydrogenation conditions Catalyst: Pd-Pll (CI-13Coo)2-A
u203 ρb /Pd atomic ratio -3. Pd content m (relative to Δtext 203) = 0, 35 wt% Temperature: 21°C Pressure: 5 kg/cm2G M2 molar ratio: 5 Ll-18V (empty column basis): 201+r-1 This styrene composition and hydrogenation conditions, Grain i￥, 2 to 4 mm
An adiabatic reaction tube having an inner diameter of 12 mm was filled with φ15d, and a hydrogenation reaction of phenylacetylene was carried out under adiabatic conditions.

As a result, all of the phenylacetylene was removed by hydrogenation, some ethylbenzene was produced, and the loss of styrene was 0.3%.
Met.

Example 2 As a catalyst, 0.35% Pd-8n (CH3Coo)2-Δ
Except for using n203, Sn / Pd atomic ratio -3,
In exactly the same manner as in Example 1, phenyla was subjected to a hydrogenation reaction of tyrene.

As a result, the conversion rate of phenylacetylene was 95%, and the loss of styrene was 0.2%.

Comparative Example 1 The phenyla was subjected to hydrogenation removal reaction of tyrene in exactly the same manner as in Example 1 except that TO, 35% Pd-AfL203 was used as a catalyst, and as a result, the phenylacetylene conversion rate was 100%, Styrene loss was 2%. That is, the production of ethylbenzene was large and the loss of styrene was excessive.

Agent Patent Attorney Sei Kikuchi

Claims (1)

[Claims] In a method of selectively hydrogenating phenylacetylene, an acetylene compound in styrene, under normal pressure or pressurized liquid phase conditions, palladium supported on alumina and periodic acid (1! A method characterized by using a catalyst containing a group metal or a salt thereof.