DE19757990A1 - Catalyst for selective hydrogenation of acetylene in ethylene@ - Google Patents

Abstract

A catalyst composition (I) for the selective hydrogenation of acetylene in an ethylene-based mixture, containing 0.005-2.0 wt% palladium as catalyst and 0.001-2.0 wt% silicon as modifier dispersed on a support comprising aluminium, titanium or silicon oxide or silicon oxide-aluminium oxide. Also claimed is (i) a process for the production of (I), and (ii) a process for the selective hydrogenation of acetylene by reacting ethylene with an acetylene content of 0.5-2.0 wt% on catalyst (I).

Description

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a Catalyst for the selective hydrogenation of acetylene and a Process for its production, in particular on a novel catalyst composition for selective Hydrogenating acetylene in an ethylene-containing mixture a low deactivation rate and towards a process its manufacture.

Ethylene is generally used as a monomer to to synthesize different types of polymers, and is obtained by thermal cracking of naphtha or catalytic cracking of petroleum gas such as B. Ethan, Propane, butane and the like. In general comprises about 0.5 ethylene produced by these processes up to 2.0% by weight of acetylene. For use as a monomer for the Synthesis of a polymer should be the concentration of Acetylene in the mixture of ethylene to a value be lowered below a suitable concentration. If the ethylene contains a large amount of acetylene, becomes the activity of a polymerization catalyst decreased, and the physical properties of the produced polymers are also deteriorated. The tolerable amount of permissible acetylene in the mixture from ethylene was 50 ppm in 1950, 10 to 20 ppm in 1960s, and has recently reached less than 2 ppm lowered.  

The small amount of acetylene in the ethylene stream is through the solvent extraction process (U.S. Patent No. 3,755,488) or by the catalyst hydrogenation process away. A commonly used method is that Hydrogenation process, which contains about 1% acetylene Ethylene flow from the top of an ethylene separation column flows, hydrogenated with a hydrogenation catalyst. The costs of the catalytic hydrogenation process are less than that the solvent extraction process.

There can be different types of transition metals Hydrogenation catalysts are used. The most important The factor of the hydrogenation process is the selectivity of the Hydrogenation catalyst to only acetylene over ethylene too hydrogenate. The higher the selectivity, the higher the ethylene yield.

As catalysts for the selective hydrogenation of acetylene in the early days sulfide catalysts, such as. B. Nickel sulfide or tungsten nickel sulfide, or Copper catalysts used. However, it is Reactivity of such catalysts low, and the reaction should be done at high temperatures, too a blocking of the catalysts due to increased Polymer deposits on the catalyst surface leads. The Blocking the pores shortens the cycle of Catalyst regeneration.

When using precious metals as selective hydrogenation catalysts reactivity and selectivity were used improved. In particular, the effectiveness of palladium was excellent.

According to a report by Bond et al. transition metal catalysts for selective hydrogenation were compared for their selectivity as follows ("Catalyst by metals", Academic Press, New York 281-309, 1962)

Pd <Rh, Pt <Ni << Ir

According to a report by Trimm et al. can Pd and Ni Compositions with triple bonds in the presence of Selectively hydrogenating compositions with double bonds, and Ni has a higher one compared to other metals Activity for the decomposition reaction (design of catalysts, Elsevier, 229-248, 1980).

Because transition metal catalysts are a relatively large Metal surface for increased hydrogenation activity required, the metal component was on a support distributed.

Furthermore, the components of the catalysts distributed the carrier so that one at the commercial Process expected excessive heat of reaction easily can be removed.

If one gram-mole of acetylene is hydrogenated to one gram-mole Generating ethylene produces more than 40 Kcal. The energy generated as heat would be accumulated locally, if the metal components are not distributed on the carrier will. The heat accumulation makes it difficult To control reactor temperature. If the reactor temperature increases, the conversion of acetylene to ethylene increases, and at the same time the partial conversion rate decreases from Ethylene to ethane too.

Since the selectivity of the catalytic Hydrogenation reaction changes with temperature, the Reaction temperature within a suitable range being held.  

In general, it is desirable to have a catalyst and to select a reactor in which raising the Temperature during the hydrogenation in the event that acetylene is completely removed, is within 15 ° C.

US Patent No. 2,511,453 discloses a method of Manufacture a catalyst that is nickel, chromium and cobalt used, the acetylene concentration after the Hydrogenation is about 50 to 100 ppm high.

US Patent No. 2,735,897 describes a method for Producing a catalyst containing 0.025 to 0.3 wt% Palladium on an alumina carrier, which as ICI-38-I (ICI Co., and G-583 (Girdler Co.) was marketed.

U.S. Patent No. 4,387,258 describes a method of Manufacture of a catalyst by distributing Components of the catalyst on one Silica support, and U.S. Patent No. 4,839,329 discloses a method of making a catalyst by distributing palladium on a titanium oxide support.

However, all of these methods cause unwanted Side reactions derived from the carrier.

The carriers used in the aforementioned patents are slightly acidic and polymerize acetylene to green oil with more than four carbon atoms.

The green oil produced blocks part of the Catalyst pores to allow reactants access to prevent the catalysts or around the active sites of the catalysts, which in turn leads to Deactivation of the catalysts leads and thus the  Regeneration cycle or the life of the catalysts shortened.

Therefore, great efforts have been made to get one Process for improving the selectivity of catalysts to develop in the selective hydrogenation of acetylene.

Although it is generally accepted that the rate of hydrogenation of Ethylene is 10 to 100 times as large as acetylene (Adv. in Catal., 15, 91-226 (1964)), acetylene over ethylene selectively hydrogenated because acetylene is added to the active sites of the hydrogenation catalysts selectively is adsorbed.

Furthermore, the rate determining step is the Hydrogenation reaction not the surface reaction step, but the adsorption and desorption step.

The adsorption parameters of hydrocarbons (Examples: acetylene, methyl acetylene, propadiene, ethylene, Propylene) on Group VIII metals such as e.g. B. Pd, were examined.

As a result, the hydrocarbons are compared for the adsorption rate as follows. The desorption rate of hydrocarbons is in reverse order (The Oil and Gas Journal 27, 66, (1972))

Acetylene <diolefin <olefin <paraffin

When diolefin fed to the stream of acetylene hydrogenation it inhibits the adsorption of ethylene so that acetylene is selectively hydrogenated without hydrogenation of ethylene.

The compounds like diolefin, which is a medium Adsorption rate compared to acetylene and ethylene,  are called moderators and we know that carbon monoxide plays a similar role as diolefin. Because diolefin the Production of green oil stimulated by the Catalyst surface is difficult to remove Carbon monoxide more suitable for use as a moderator.

U.S. Patent Nos. 3,325,556 and 4,906,800 describe each have a method to improve selectivity Add a very small amount of carbon monoxide to the Reactants.

If a trace of carbon monoxide is added, the Selectivity of the catalysts for the hydrogenation improved, and there is a Carbonylation, and the formation of green oil, which is a mixture from polymers with more than four carbon atoms elevated. These side effects accelerate the Catalyst deactivation and shorten the Regeneration cycle or the life of the catalysts.

SUMMARY OF THE INVENTION

The present invention aims to do the above mentioned problems with conventional catalytic To solve hydrogenation processes which prevent the formation of By-products such as B. green oil, cause the Deactivation of catalysts accelerated and the Regeneration cycle shortened.

The object of the present invention is a To provide catalyst for the hydrogenation, the one has high selectivity without the addition of carbon monoxide and the side reactions such. B. the polymerization or Carbonylation, eliminated to the activity of the Maintain catalyst and the life of the  Extend catalyst, as well as the manufacturing process to provide for it.

The other object of the present invention is therein a process for the selective hydrogenation of acetylene to provide by using a mixture of ethylene, the 0.5 contains up to 2.0% by weight of acetylene, with the catalyst composition of the present invention.

BRIEF DESCRIPTION OF THE DRAWING

Figure 1 is an analysis of the selective hydrogenation of acetylene from a palladium catalyst distributed on an alpha alumina support and containing chemically deposited silicon.

FIG. 2 shows the temperature dependence of the selectivity of different catalysts, one of which contains chemically deposited silicon and the other is present without deposited silicon.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a novel one Catalyst for the selective hydrogenation of acetylene in one Mixture of ethylene, the 0.5 to 2.0 wt .-% acetylene contains, and on the process for its preparation.

The present invention also relates to a Catalyst for the selective hydrogenation of acetylene in one Mixture of ethylene, which has a high selectivity without the addition of carbon monoxide and side reactions such. B. the polymerization, or cabonylation, is eliminated in order to maintain the activity of the catalyst and the Extend the life of the catalyst, as well as on the Process for its manufacture.  

For this, the present invention is concerned with a Catalyst composition for the selective hydrogenation of Acetylene in a mixture of ethylene, the Catalyst composition is prepared by 0.005 to 2.0 wt .-% palladium as a hydrogenation catalyst and 0.001 to 2.0 wt .-% silicon as a modifier distributed at least one carrier, which is under aluminum oxide, Titanium dioxide, silicon oxide and silicon aluminum oxide is selected, the palladium preferably 0.01 to 0.2% by weight, the silicon is preferably 0.005 to 0.2 % By weight and the silicon is at least one selected organic silane compound such as tetrahydrosilane, Triethylsilane, tripropylsilane, phenylsilane and the like having.

Optionally, the catalyst composition of the present invention further 0.03 to 2.0 wt .-% of a Have transition metal as co-catalyst, which one under Selects nickel, cobalt, silver and the like. Farther can optionally 0.03 to 1.0 wt .-% of an alkali metal added to the catalyst composition as a promoter be that one under sodium, potassium, calcium and selects the like.

The catalyst composition of the present invention is prepared by a process in which at least one Carrier, which one under aluminum oxide, aluminum titanium dioxide, Selects silica and silica-alumina, in immerses a palladium salt solution which is 0.005 to 2.0% by weight Contains palladium, after which the carrier is dried, is calcined at 300 to 700 ° C and then after Carrying out a reduction at 50 to 500 ° C under one Hydrogen flow 0.001 to 2.0 wt .-% silicon on the Catalyst is also chemically separated. This Palladium salt is at least one salt that one under  Palladium halide, palladium nitrate and palladium acetylacetonate selects.

The 0.03 to 2.0 wt .-% of the transition metal as a cocatalyst and 0.03 to 1.0% by weight of the alkali metal as a promoter can also be carried on the carrier together with the Palladium salt can be distributed.

The catalyst composition of the present invention contains 0.005 to 2.0% by weight as the hydrogenation catalyst, preferably 0.01 to 0.2% by weight, palladium as cocatalyst, 0.03 to 2.0 wt .-% of the transition metal as Promoter, 0.03 to 1.0 wt .-% alkali metal as Modifier, 0.001 to 2.0% by weight, preferably 0.005 up to 0.2% by weight, silicon, on at least one Distributed carrier, which under aluminum oxide, titanium dioxide, Silicon oxide and silicon oxide-aluminum oxide selected becomes.

The co-catalyst of the transition metal and the promoter of the alkali metal are optional.

Nickel, cobalt, silver and the like can be used, and as an alkali metal Sodium, potassium, calcium and the like can be used.

The palladium salt (example: palladium halide such as Palladium chloride, palladium nitrate, palladium acetylacetonate) is used to palladium to provide. The carrier made of aluminum oxide, titanium dioxide, Silica, silica-alumina and the like is immersed in the palladium salt solution, wherein then between room temperature and 200 ° C, preferably 50 up to 150 ° C, is dried.  

The dried catalyst was at 300 ° C to 700 ° C, preferably 400 to 600 ° C, over 1 to 5 hours at the Air calcined.

The calcined catalyst was added with nitrogen Rinsed at room temperature to remove oxygen, and then an activation at 50 to 500 ° C, preferably 250 to 400 ° C, over 1 to 5 hours in one Exposed to hydrogen flow.

If the co-catalyst and the promoter are additional are added, the solution of palladium salt and the solution of the metal salt of the co-catalyst and the Prepared promoter in which the carrier is immersed. The same drying and calcining treatment that is on immersion follows, under the same condition as performed the condition mentioned above.

Silicon was introduced into the catalyst by a chemical deposition process using organic silane or tetrahydrosilane (SiH ₄ ).

At least one can be used as the organic silane be that under triethylsilane, tripropylsilane and Selects phenylsilane.

The catalyst after drying and calcining is in filled a reactor with a fixed bed and then exposed to a chemical deposition process by one tetrahydrosilane or diluted in hydrogen organic silane over the catalyst at 100 to 600 ° C, preferably 300 to 500 ° C, can flow. After being the Oxidation at 15 to 700 ° C, preferably 15 to 100 ° C it was exposed to air for 1 to 5 hours at 50 to 500 ° C, preferably 250 to 400 ° C, over 1 to Activated in a stream of hydrogen for 5 hours.  

The chemical deposition process of Silicon can also be added to the ordinary Catalyst used to hydrogenate a To provide catalyst composition that a improved selectivity and a slow Deactivation rate.

In experiments on the selective hydrogenation of acetylene in the presence of the catalyst composition of the present invention was ethylene with 0.65 vol.% Acetylene used as a reactant.

Hydrogen and carbon monoxide as reactants were used diluted with ethylene. The concentration is 8.98 vol.%, 9.26 ppm, and that in the reactor Amounts to be introduced were with a flow controller set.

The reaction temperature is 40 to 140 ° C and preferably 60 to 100 ° C. The space velocity of the Reactant is 200 to 2000 (ml / min. G Catalyst) and preferably 400 to 1000 (ml / min. G Catalyst).

The performance of the catalyst is evaluated according to the following formula:

Conversion = ΔA / A ₀
Selectivity = ΔB / ΔA = ΔB / (ΔB + C)
Yield = ΔB / A ₀
A ₀ = acetylene concentration in the initial state
ΔA = changed amount of acetylene
ΔB = changed amount of ethylene
C = amount of production of ethane

The catalyst composition of the present invention showed an improved selectivity and a prolonged Catalyst life compared to conventional ones Catalysts.

Fig. 1 shows the result of the catalytic hydrogenation reaction in Example 1 of the present invention.

The catalyst composition with chemically deposited silicon (hereinafter referred to as "deposited catalyst"), in particular "catalyst 4 ", demonstrates the excellent selectivity and leads to a high yield compared to catalyst 1 which does not contain chemically deposited silicon (hereinafter) referred to as a "non-deposited catalyst").

Fig. 2 shows the dependence of the selectivity of the reaction temperature of the deposited catalyst and the non-deposited catalyst in Example 1.

The catalyst 4 , which is a deposited catalyst, has better selectivity over a wide reaction temperature range compared to catalyst 1 , which is an unseparated catalyst. As shown in Table 3 of Example 1, the catalyst 4 also has a lower deactivation rate and a longer catalyst life.

The catalyst composition of the present invention has good selectivity without the addition of carbon monoxide in the selective hydrogenation of acetylene, one Mixture of ethylene, the 0.5 to 2.0 wt .-% acetylene contains, with hydrogen on the catalyst  Reacts composition that 0.005 to 2.0 wt .-% a hydrogenation catalyst, palladium and 0.001 to 2.0% by weight of a modifier and silicon, and distributed on at least one carrier that one among alumina, titanium dioxide, silicon oxide and Selects silicon-aluminum oxide. The catalyst composition of the present invention Side reactions, such as. B. the polymerisation or Carbonylation, and thus prevents the rate of deactivation and extends the active life of the catalyst.

Thus, the hydrogenation of acetylene can occur in the mixture Ethylene can be carried out effectively.

The present invention can be accomplished by the following Examples are better understood, but these Examples serve to illustrate the invention and not limiting the scope of the invention are to be understood.

example 1 1) Preparation of the catalyst

25 mg PdCl ₃ was dissolved in 40 g 3% HCl solution. 50 g of alumina (α-shape, 3 mm in diameter, spherical 60 m ² BET surface area, 200 Å average pore size) was added to the solution to be kept for 2 to 3 hours and then in the oven at 100 ° C for 4 to 4 hours To be dried for 5 hours.

The dried catalyst was in the air at 25 ° C oxidized for 2 hours.

The catalyst was then purged with nitrogen to remove oxygen at room temperature and was then subjected to hydrogen flow activation at 400 ° C for 2 hours. The catalyst produced is called catalyst 1 . Catalyst 1 comprises 0.003 wt% Pd.

5 g of catalyst 1 are placed in a tube in a fixed bed. 1% SiHi ₄ / H ₂ gas was flowed over the catalyst at 20 ml per minute at 400 ° C to be deposited thereon, and it was then subjected to calcination under an atmosphere at 25 ° C for 2 hours and activated under a hydrogen stream at 400 ° C for 2 hours.

Different types of catalysts have been made in accordance with the present invention in which the deposition time is 5, 10, 15, 20 and 50 minutes, respectively. The catalysts are each referred to as catalyst 2 , catalyst 3 , catalyst 4 , catalyst 5 and catalyst 6 . The silicon content of the catalysts is 0.0025, 0.005, 0.0075, 0.010 and 0.020% by weight, respectively.

2) Hydrogenation using a catalyst

1 g of each of the catalysts 1 to 6 produced was placed in a 1/2 inch tube of a stainless steel reactor and then subjected to hydrogenation under the following conditions:

Reaction temperature: 100 ° C
Hydrogen / acetylene: 3/1 (molar ratio)
Reagent space velocity: 800 (ml / min.g catalyst)

The result of the reaction is shown in Fig. 1.

If one compares the deposited catalyst with the non-deposited catalyst, the conversion is similar, while the yield on the deposited catalyst is higher than shown in the drawing. In particular, the catalyst 4 has more than 3 times the yield of the non-deposited catalyst.

3) Effect of the hydrogen / acetylene molar ratio

With the catalyst 1 and the catalyst 4 , the hydrogenation was carried out in the same manner as in Example 1, except that the reaction condition of the hydrogen / acetylene molar ratio was changed.

The result is summarized in Table 1.

Changes in hydrogenation results according to the hydrogen / acetylene molar ratio

Changes in hydrogenation results according to the hydrogen / acetylene molar ratio

If the hydrogen / acetylene molar ratio is increased, the conversion is increased and the selectivity is increased.

In the case of the catalyst 1 , the selectivity has a negative value when the hydrogen / acetylene molar ratio is 4. This is attributed to the fact that not only hydrogenation of acetylene, but also hydrogenation of ethylene is carried out to a considerable extent, so that the total amount of ethylene is reduced.

In the case of the catalyst 4 , the selectivity decreases only slightly even when the hydrogen / acetylene molar ratio is high. This confirms that the catalyst of the present invention effectively controls the hydrogenation of ethylene.

4) Effect of carbon monoxide

Hydrogenation was carried out on the catalyst 1 and the catalyst 4 in the same manner except that the carbon monoxide concentration was adjusted as follows. The result is summarized in Table 2.

Changes in hydrogenation results depending on the concentration of carbon monoxide

Changes in hydrogenation results depending on the concentration of carbon monoxide

In the case of the catalyst 1 , the conversion is reduced, but the selectivity and the yield increase as the concentration of carbon monoxide is increased.

It can be seen that the selectivity and the yield of the catalyst 1 are small compared to the catalyst 4 .

The catalyst 4 of the present invention has a high selectivity and good yield without adding any carbon monoxide compared to the conventional catalyst, so that the phenomenon of green oil formation and the deterioration of the catalytic performance due to the addition of carbon monoxide are changed.

5) Effect of the reaction temperature

The reaction was carried out separately at the different temperatures with the catalyst 1 and the catalyst 4 .

The result is summarized in Fig. 2. When the reaction temperature is increased, the selectivity is reduced with both catalyst 1 and 4 . And if the conversion is the same, the catalyst 4 has the highest selectivity.

6) Deactivation of the catalyst

Catalyst 1 and Catalyst 4 were subjected to a series of reactions under the following conditions for 30 hours and the rate of deactivation was measured. The result is summarized in Table 3.

Reaction temperature: 120 ° C
Hydrogen / acetylene: 3/1 (molar ratio)
Reagent space velocity: 800 (ml / min.g catalyst)

Deactivation rate of the catalyst

Deactivation rate of the catalyst

The more carbon monoxide added, the faster the deactivation rate. The catalyst 4 , which has chemically deposited silicon, has a reduced deactivation rate.

As observed in the above results with Catalysts 1 and 4 under the different reaction conditions, Catalyst 4 , which has chemically deposited silicon, maintains high selectivity and good yield in a wide range of reaction temperatures and the hydrogen / acetylene molar ratio. The deposited catalyst has a relatively prevented deactivation rate compared to the non-deposited catalyst.

Example 2

Organic silane was used instead of tetrahydrosilane (SiH ₄ ) as a substance for silicon deposition.

The catalyst was replaced by the same process as in Example 1 prepared with the exception that silicon on chemically deposited the catalyst from organic silane by converting hydrogen gas to one with the organic silane-filled liquid saturators let.

The hydrogenation was carried out under the following conditions carried out.

The result is summarized in Table 4.

Reaction temperature: 100 ° C
Hydrogen / acetylene: 1/3 (molar ratio)
Reagent space velocity: 800 (ml / min.g catalyst)

Activity of the catalyst with deposited silicon

Activity of the catalyst with deposited silicon

Regardless of the type of silane used, observed a similar reactivity, confirming that the impact of chemically deposited silicon is maintained.

Example 3

The catalyst was prepared by the same process for the preparation of the catalyst 4 as in Example 1, except that titanium dioxide, silicon oxide and aluminum oxide were used instead of aluminum oxide as a carrier.

The hydrogenation was carried out under the following conditions. The result is summarized in Table 5.

Reaction temperature: 120 ° C
Hydrogen / acetylene: 3/1 (molar ratio)
Reagent space velocity: 800 (ml / min.g catalyst)

Effect of the wearer

Effect of the wearer

The catalyst with titanium dioxide, silicon oxide and Silica-alumina as a support appears to be a similar one Reactivity as the catalyst with alumina as To have porters.

This shows that the effect of chemically deposited Silicon regardless of the type of carrier used is maintained.

Example 4

The catalyst was prepared by the same process as for the preparation of Catalyst 4 described in Example 1, except that the components of the co-catalyst and promoter were added.

5 g of the catalyst 1 in Example 1 was immersed in the appropriate amount of the solution of nickel nitrate, cobalt acetate or silver nitrate and then dried. The dried catalyst 1 was immersed in the appropriate amount of the alkali salt solution and then dried in an oven at 100 ° C and then calcined at 400 ° C for 2 hours. This calcined catalyst 1 was put in a tube of a fixed bed and subjected to silicon deposition by flowing 1% SiH ₄ / H ₂ gas at 20 ml / min at 400 ° C, and was over at 25 ° C oxidized for two hours and then activated at 400 ° C for 2 hours to provide the catalyst.

The hydrogenation was carried out under the following conditions. The result is summarized in Table 6.

Reaction temperature: 120 ° C
Hydrogen / acetylene: 3/1 (molar ratio)
Reagent space velocity: 800 (ml / min.g catalyst)

Effect of the co-catalyst and promoter

Effect of the co-catalyst and promoter

If the co-catalyst and the promoter are also in the Catalyst are added, the catalyst tends to Increase in conversion and decrease in Selectivity.

A result similar to that for the catalyst 4 produced in Example 1 is essentially observed.

This shows that the effect of chemically deposited Silicon is retained even in the event that the cocatalyst and the promoter can be added.

Claims (8)

1. Catalyst composition for selective hydrogenation of acetylene in a mixture of ethylene that is 0.005 to 2.0% by weight of palladium as a hydrogenation catalyst and 0.001 up to 2.0% by weight of silicon as a modifier on at least distributed a carrier which is under aluminum oxide, Titanium dioxide, silicon oxide and silicon oxide-aluminum oxide is selected. 2. A catalyst composition according to claim 1, wherein the Palladium content 0.01 to 0.2 wt .-% and silicon 0.005 to 0.2% by weight. 3. A catalyst composition according to claim 1, wherein the Silicon from at least one organic silane is deposited, which is under tetrahydrosilane, Triethylsilane, tripropylsilane and phenylsilane selected becomes. 4. Catalyst composition according to one of claims 1 to 3, which further 0.03 to 2.0 wt .-% of a Transition metal, which is called nickel, cobalt and silver selects, as co-catalyst and 0.03 to 1.0 wt .-% of one Alkali metal, which is sodium, potassium and calcium selects as a promoter. 5. Process for the preparation of a catalyst composition for the selective hydrogenation of acetylene in a mixture of ethylene, characterized in that at least one carrier, which one under aluminum oxide, Titanium dioxide, silicon oxide and silicon oxide-aluminum oxide selected, is immersed in a palladium salt solution, so that 0.005 to 2.0% by weight of palladium is distributed thereon; of the The carrier is then dried at 300 to 700 ° C  is calcined and then at 50 to 500 ° C under one Hydrogen flow is activated and then a chemical Deposition of 0.001 to 2.0 wt .-% silicon Silane compounds is exposed. 6. Process for the preparation of the catalyst composition according to claim 5, wherein the palladium salt is at least one salt made from palladium halide, Palladium nitrate and palladium acetylacetonate. 7. Process for the preparation of the catalyst composition according to claim 5 or 6, wherein 0.03 to 2.0 Wt .-% of a co-catalyst from a transition metal and 0.03 to 1.0 wt .-% of a promoter made of an alkali metal together with the palladium salt as a carrier. 8. Process for the selective hydrogenation of acetylene by ethylene containing 0.5 to 2.0% by weight of acetylene the catalyst composition according to claim 1 react leaves.