JPS63230643A - Selective hydrogenation of acetylene compound - Google Patents

Abstract

PURPOSE:To enable selective hydrogenation of an acetylene compound existing as an impurity in a fraction composed mainly of 4C hydrocarbons containing 1,3-butadiene, by hydrogenating with dissolved hydrogen in pressurized liquid phase in the pressure of a Pd-based solid catalyst supported on a carrier. CONSTITUTION:In the selective hydrogenation of an acetylene compound in a fraction composed mainly of 4C hydrocarbons containing 1,3-butadiene, the reaction is carried out at 5-60 deg.C in liquid phase in the presence of more than equimolar amount of dissolved hydrogen based on the acetylene compound using a solid catalyst containing Pd element in an amount of 0.001-0.04wt.% based on a carrier (e.g. gamma-Al2O3). The catalyst may contain a cocatalyst such as inorganic acid salt or organic acid salt of Cu, Ag, Au, Pb or Zn. Multi-stage hydrogenation reaction is used in the case of high acetylene concentration and the control of reaction heat can be easily carried out.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to
- A method for hydrogenating an acetylene compound which is an impurity in a fraction mainly composed of hydrocarbons having 4 carbon atoms (hereinafter referred to as "C4 fraction") including butatsuene.

[Conventional technology]

The C4 fraction obtained by cracking petroleum products mainly contains 1,3-butadiene, isobutyne, n-butene (
Butene-1,! Ten-2), butanes, and contains small amounts of C4 acetylene compounds such as vinyl acetylene and ethyl acetylene as impurities, and in some cases, trace amounts of C3 acetylene compounds such as methyl acetylene (hereinafter referred to as "acetylene compounds"). ).

When this C4 fraction, especially the 1,3-butadiene contained therein, is separated and used as a raw material for rubber, f-plastic, and other chemical industries, the acetylene compounds contained as impurities pose various obstacles. It must be removed by appropriate treatment in advance so that the concentration is below a certain level.

C2 containing 1,3-butadiene or 1,3-butadiene
As a method for removing acetylene compounds in a fraction, a method has conventionally been used in which acetylene compounds are selectively hydrogenated under gas phase or liquid phase conditions in the presence of a catalyst.

However, in this method, there is generally little difference in reactivity between 1,3-butadiene (hereinafter referred to as "butadiene") and an impurity acetylene compound, and the concentration of the acetylene compound to be hydrogenated is determined by the concentration of butadiene. It is extremely difficult to suppress the hydrogenation of butadiene as much as possible and selectively and sufficiently hydrogenate only the acetylene compound.

For example, in the gas phase method, the reaction is usually carried out at a temperature of about 150 to 200°C, but in the reaction at such a high temperature, the hydrogenation reaction and polymerization of butadiene are severe, and a considerable amount of butadiene is inevitably lost. The deterioration of the catalyst due to adhesion of molecular substances is also significant.

On the other hand, in the liquid phase method, the reaction is usually carried out at a relatively low temperature of 100°C or less, so there are fewer drawbacks such as catalyst deterioration compared to the gas phase method. It is also difficult to avoid the disadvantage that it is necessary to use a considerably large amount of hydrogen, which increases the proportion of the hydrogenation reaction of butadiene.

In view of the current situation, the present inventors have proposed a method of selectively hydrogenating acetylene compounds in a C4 fraction by a liquid phase method.

For example, regarding catalysts, A'ranium and the first part of the periodic table are
Combinations of group Vb metals or their salts (Unexamined Japanese Patent Publication No. 5
7-185229), a technology characterized in that the hydrogenation reaction is carried out in a substantially anhydrous system (Japanese Patent Application Laid-Open No. 57-206627), C desulfurized with a desulfurizing agent
A technology characterized by the use of ash distillate raw materials (Japanese Patent Application Laid-open No. 5
9-196828) etc.

[Problem that the invention seeks to solve]

In these conventional techniques, in order to reduce the concentration of acetylene compounds in the C4 fraction to a certain level, it is required to supply a large amount of hydrogen to the liquid phase reaction system, which creates air bubbles in the reaction system. Hydrogen was present, and hydrogen was unevenly distributed within the reaction system. In addition, in order to fully demonstrate the catalytic performance, the amount of mother radium supported on the catalyst carrier was increased to accelerate the hydrogenation reaction.

As a result, not only the acetylene compound but also the hydrogenation reaction of butadiene, which is an active ingredient, was lost.

[Means for solving problems]

In order to solve such problems, the present invention aims to convert acetylene compounds in a fraction mainly composed of butadiene or a hydrocarbon having 4 carbon atoms containing butadiene into a pressurized liquid phase in the presence of an /IP radium-based solid catalyst. In the method of hydrogenation in
0.001 of palladium in solid catalyst to catalyst carrier
It has been discovered that the hydrogenation reaction proceeds selectively in the presence of dissolved hydrogen in the liquid phase at a concentration of ~0.04% by weight and in an amount of 1 mole or more relative to the acetylene compound, and has completed the method of the present invention. It's arrived.

In the case of the present invention, the concentration of radium in the catalyst is characteristic, and in order to minimize the loss of butadiene in the raw C4 fraction due to hydrogenation and to selectively hydrogenate acetylene compounds, it is necessary to A concentration of 0.001-0.04% by weight is important.

In a liquid phase hydrogenation reaction, increasing the reaction pressure and increasing the dissolved hydrogen concentration in the liquid phase accelerates the hydrogenation rate of both butadiene and acetylene compounds, but in this case, as disclosed in the prior art, As long as a catalyst with a high palladium concentration of 0.1 to 0.5% by weight is used, the hydrogenation rate of butadiene becomes even faster due to the butadiene concentration in the C4 fraction, and the acetylene compound is significantly The selectivity of K decreases.

Prior art palladium loading concentrations are inadequate to provide sufficient selectivity, and lowering the concentration would yield favorable results.

It is assumed that reducing the palladium concentration in the catalyst improves reaction selectivity by reducing the number of active sites for the reaction and suppressing the reactivity of butadiene and hydrogen, especially butadiene, which participate in the competitive reaction. be done. The improvement in selectivity is also presumed to be due to the adsorption of the acetylene compound to the catalyst, and as the number of active sites for one reaction decreases, the rate of hydrogenation of the acetylene compound is accelerated.

There is a lower limit to the reduction of the number of reactive sites, and if the parasium concentration in the carrier is less than dZO, 0.001% by weight, the hydrogenation reaction of the acetylene compound will also be sharply reduced. If the palladium concentration exceeds 0.04% by weight, this will lead to a decrease in the selectivity of acetylene compounds, which is a feature of the present invention.

Although it is essential that the catalyst used in the present invention contains palladium as a main component, other metal salts such as copper, silver, gold, tin, zinc, cadmium, or inorganic acid salts of lead may be used as co-catalyst components. Any known material containing an organic acid salt or the like can be used.

As a catalyst carrier, r-At20. , 77-At2
0. , θ-At203, and other known materials can be used.

- The promoter component that may be added to radium preferably has a metal atomic ratio in a known range of 0.1 to 20. Naturally, when reducing the .9 radium concentration, it is desirable to change the amount of the co-catalyst component added accordingly to obtain an optimum value.

Next, the second feature of the present invention is that the hydrogenation reaction is carried out in the presence of a certain concentration or more of dissolved hydrogen. In order to increase the hydrogen addition rate as much as possible without leaving bubble hydrogen in the system, it is necessary to increase the concentration of dissolved hydrogen. C
The solubility of hydrogen in the 4 fractions increases approximately in proportion to the pressure, but at a pressure of 13 Kg/crn2G it is approximately 0.4
The mol% is about 1.8 mol% at 30 Kp/cm''G, but this value varies depending on the C4 fraction composition and the temperature of the liquid.

The concentration of acetylene compounds in the C4 fraction is 0.5 to 1.0
In the case of weight%, the reaction pressure is 10-60Kg/cm"G
You can choose from the range as appropriate.

The theoretical value of hydrogenation with respect to the total concentration of acetylene compounds is 1, and if the dissolved hydrogen concentration is less than this, hydrogenation of the acetylene compounds becomes insufficient.

Known methods can be used to dissolve hydrogen in the C4 fraction. For example, a 1/4 to 3/4 alumina packed column is placed under a predetermined pressure at 20 Kf/c! ! Keep it at L”G,
In order to improve solubility, a distributor having a diameter of φ211II is provided.

There is no particular limit to the concentration of acetylene compounds in the C4 fraction, but there is a limit to the dissolved concentration in the fraction, which is determined by pressure.In order to obtain a product that meets the required specifications, two or more stages of the hydrogenation reaction are required. This may also be necessary if the process is performed in multiple stages. C4
Considering the acetylene compound concentration in the fraction, the dissolved hydrogen concentration under the reaction pressure used, the hydrogenation rate of the acetylene compound, etc., and taking into account the minimum loss of butadiene,
The required number of stages is determined.

If such a multistage hydrogenation reaction is taken into account, it is possible to remove the acetylene compounds coexisting in the C4 fraction by hydrogenation even if the total concentration is 0.5 to 3% by weight.

In the case of multistage hydrogenation, for example, two stages, the catalyst used for the first and second stage hydrogenation should be within a range that does not reduce the hydrogenation rate of acetylene in the second stage, where the concentration of the 04 acetylene compound decreases, considering selectivity. So, tJ from the first stage? Although it is preferable to use a catalyst with a low radium concentration, there is no problem in using catalysts with the same palladium concentration in both the first and second stages.

The reaction temperature is 0 to 80°C, preferably 5 to 60°C, and LH
8V is 2-200hr, preferably 4-150hr
The reaction temperature is set at a temperature at which the reaction system can substantially maintain a liquid phase.

The hydrogen used in the present invention may be pure or diluted with an inert gas, such as methane.

The reaction type is preferably a catalytic or fixed bed type, and either a flowing type or an overflow type can be adopted to carry out the fixed bed reaction in a liquid phase.

Further, as the reactor, either an isothermal type or an adiabatic type can be used.

The method according to the present invention has the following advantages by employing a hydrogen dissolution method in which the problem of gas-liquid contact does not occur in the reaction.

(1) Since the hydrogenation reaction is carried out with dissolved hydrogen, hydrogen and C
No special measures are required to improve the dispersion of the four fractions, which is advantageous in terms of equipment.

(2) When the acetylene concentration in the C4 fraction is high, the hydrogenation reaction may be carried out in multiple stages, and the reaction heat can be easily controlled.

(3) The catalyst remains effective even at extremely low palladium concentrations, which is economically advantageous.

Next, examples of the present invention will be shown to specifically explain the invention.

In both Examples and Comparative Examples, the raw C4 fraction is passed through a pretreatment tower that adsorbs and removes the catalyst and poisoning components in the raw material, and then the C4 fraction is
A predetermined amount of hydrogen was mixed with the fraction, passed through a packed column for dissolving hydrogen, and after the hydrogen was completely dissolved, the mixture was introduced into a hydrogenation reactor and reacted.

〔Example〕

In Examples 1 to 4 and Comparative Examples 1 to 3, a reactor with a catalyst amount of 7514 was used, and the hydrogenation reaction was performed in one stage.

The results are shown in Table 1.

Example 1 (1) C4 fraction raw material composition Butane 8.90 wt% n-butene 23.50 Isobutyne 24.90 1.3-butanoene 42.09 Ethyl acetylene 0.13 Vinyl acetylene
0.48 Methylacetylene Trace amount Glopadiene Trace amount (2) Reaction conditions for hydrogenation Reaction type: Isothermal reaction temperature = 38℃ Reaction pressure: 31Kp/cWL2GLH8v:14
hr-1 Dissolved hydrogen concentration: 1.7 mol% Dissolved hydrogen molar ratio: 2.8 (to C4 acetylene compound)
(3) Catalyst composition used: Pd-Pb(CH3COO)2-At2
0. .

Pb/Pd atomic ratio = atomic ratio phase 4 ratio: 0.02wt% (vs. At2o3) particle size
:2~4uφ (spherical) Example 2゜Among the reaction conditions, the reaction temperature was 21℃ and LH8V was 30h.
It is the same as Example 1 except that r is changed.

Example 3 The reaction conditions were the same as in Example 1 except that the reactor was of an adiabatic type and the inlet temperature of the C4 fraction was changed to 10°C.

Example 4 Catalyst: Pd-Pb(CH3COO)2-At203.
Pb/Pd atomic ratio: 4Pd loading rate” 0.002 w
It is the same as Example 1 except that t% (vs. At20.) was changed.

Comparative Example 1゜Catalyst: Pd-Pb(CH3COO)-At20.
, Pb/Pd atomic ratio: 4Pd support rate -0.35, wt
% (vs. ht2o3) is the same as in Example 1 except for the change.

Comparative Example 2 The same as Comparative Example 1 except that the reaction pressure was changed to 20 Kf/m''G.

Comparative Example 3 The same as Comparative Example 1 except that the reaction pressure was changed to 8 Kf/cm''G.

As is clear from Table 1, Examples 1 to 4 show less loss of 1,3-butadiene than Comparative Example 1. In particular, Examples 1 to 3 maintain a high removal rate of acetylene compounds, and・Loss of diene is small.

Comparative Examples 2 and 3 have insufficient removal rates of acetylene compounds.

Example 5 Two reactors each having a catalyst amount of 1.2 m3 were used to carry out the hydrogenation reaction in two stages.

(1) C4 fraction raw material composition Same as Example 1 (2) Reaction conditions for hydrogenation 1st stage reactor Reactor type: Adiabatic C4 fraction inlet temperature: 23°C Reaction pressure: 31 Kg / ctn2GLH8V
:, 14 hr 'Dissolved hydrogen concentration: 1.
8 mol% Dissolved hydrogen molar ratio: 3 (to C4 acetylene) ■The dissolved hydrogen concentration in the second stage reactor is 1.6 mol%, and the dissolved hydrogen molar ratio is 23
It is.

Other than this, the conditions are the same as those of the first stage reactor.

(3) Catalyst Used Both the first stage reactor and the second stage reactor were filled with the same amount of the same catalyst to carry out the hydrogenation reaction as follows.

Pd loading rate: 0.02wt% (vs. At203) Particle size
: 2 to 4 φ (spherical) As a result of performing a two-stage selective hydrogenation reaction under these conditions,
The concentrations of ethyl acetylene and vinyl acetylene in the C4 fraction at the outlet of the second stage reactor were 35 and 3 wt ppm, respectively.
The removal rates were 97.3% and 99.9%, respectively.

The 1,3-butanoene concentration was 40.4 wt%, and the loss rate was 4.0%.

〔Effect of the invention〕

As described above, the method of the present invention is a method in which acetylene compounds in the C4 fraction are removed by hydrogenation, and at this time, the loss of butadiene, an active ingredient, is reduced.

Furthermore, since the hydrogenation reaction can be carried out in a state where hydrogen is dissolved, it is an excellent method with a stable removal rate of acetylene compounds.

Claims (1)

[Claims] An acetylene compound in a fraction mainly composed of 1,3-butadiene or a hydrocarbon having 4 carbon atoms containing 1,3-butadiene is converted into a pressurized liquid phase in the presence of a palladium-based solid catalyst. In the method of hydrogenating the solid catalyst, the palladium element in the solid catalyst is
．． 001 to 0.04% by weight, and the hydrogenation reaction is carried out in the presence of dissolved hydrogen in a liquid phase in an amount of 1 mole or more relative to the acetylene compound.