JPS58210854A - Regeneration method of catalyst for selective hydrogenation - Google Patents

Abstract

PURPOSE:To restore catalytic activity, by heating a Pd catalyst which is deteriorated in the activity for selective hydrogenation of an acetylene compd. in olefin in air or the like then reducing the same with hydrogen or further depositing a promoter again thereon. CONSTITUTION:If a catalyst which consists essentially of Pd and is deposited thereon with one kind of the inorg. acid salt, org. acid salt or oxide of Cu, Au, Ag, Sn, Zn, Cd, Pd, etc. as a promoter and is used for removing an acetylene compd. which is an impurity in olefin hydrocarbon of 3-4 carbon atoms obtd. by cracking or the like of petroleums by selective hydrogenation is deteriorated in the activity thereof, such catalyst is heated in air or an inert gas contg. oxygen at 150-500 deg.C. The catalyst is then heated to 50-300 deg.C in gaseous hydrogen flow and is thus reduced or further the above-mentioned metallic salt as a promoter is deposited again thereon and is dried, whereby the catalyst having the restored activity is regenerated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to the use of a distillate mainly composed of olefin hydrocarbons having 3 to 4 carbon atoms (hereinafter, C
It is called 3-4 fraction. ), the catalyst is regenerated by selectively hydrogenating the acetylene compound under pressurized liquid phase conditions. active moth
- A method characterized by heating at high temperature in a gas atmosphere, followed by hydrogen reduction, or re-supporting and regenerating the co-catalyst component after hydrogen reduction.

The 03-4 fractions obtained by cracking petroleum products mainly contain propylene, 1,3-butadiene, isobutyne, n-butene (butene-1, butene-2), propane,
It consists of butanes, and contains small amounts of acetylene compounds such as acetylene, methylacetylene, ethyl acetylene, and vinyl acetylene as impurities, and in some cases, impurities such as -C allene (propadiene),
It may also contain diene compounds such as methyl allene.

When separating this C3-4 fraction and using it as a raw material for rubber, 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.

Conventionally, as a method for removing acetylene compounds in C3-4 fractions, acetylene compounds are selected by suppressing hydrogenation of the main components olefins and diolefins as much as possible under gas phase or liquid phase conditions in the presence of a catalyst. A method of hydrogenation is currently being used.

However, in the conventionally known methods, it is very difficult to selectively and sufficiently hydrogenate only the acetylene compounds while suppressing the hydrogenation of the olefins and diolefins, which are the main components, as much as possible. Particularly in the case of C4 fractions, there is generally little difference in reactivity between 1,3-butadiene and the impurity acetylene compound, and the concentration of the acetylene compound to be hydrogenated is extremely low compared to the concentration of butadiene. Therefore, it is very difficult to selectively and sufficiently hydrogenate only the acetylene compound while suppressing the hydrogenation of butadiene as much as possible. For example, in the gas phase method, the reaction is usually carried out at a concentration of about 150 to 200°C, but in the reaction at such high temperatures, hydrogenation and polymerization of butadiene are severe, and a considerable amount of butadiene is inevitably lost. Deterioration of the catalyst due to adhesion of substances is also significant. On the other hand, in the liquid phase method, the reaction is usually carried out at a relatively low concentration below 100°C, so there are fewer drawbacks such as catalyst deterioration compared to the gas phase method, but on the other hand, it is difficult to completely hydrogenate the acetylene compound. 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 hydrogenation of butadiene.

Even in the liquid phase method, depending on the properties of the 03-4 fractions, if the catalyst is used for a long period of time, catalyst poisoning components such as polymers and water will gradually accumulate, reducing the catalytic activity and causing butadiene loss. It may increase. Various methods are known for regenerating a catalyst that has experienced a decrease in iM activity. For example, known methods include performing calcination in air, burning off the polymers accumulated on the catalyst, and then re-reducing and activating the catalyst, or washing with an appropriate solvent. However, catalysts that can be regenerated by combustion using air must have heat resistance, and excellent catalysts with high activity and low butadiene loss have low heat resistance and cannot be used in such regeneration methods. In many cases, it cannot be removed, and it is desired to develop a method for recycling it.

In view of the current situation, the present inventors have developed an effective regeneration method for palladium-metal salt or metal oxide solid catalysts that selectively hydrogenates acetylene compounds in C3-4 fractions. As a result of various studies, we have found a method in which the catalyst with decreased activity is heated at high temperature in air or an oxygen-containing inert gas atmosphere, and then reduced with hydrogen, or after hydrogen reduction, the co-catalyst component is re-supported. I found it to be excellent.

The main component of the catalyst used in the present invention is palladium, and co-catalysts include other metal salts or metal oxides, such as inorganic acid salts of copper, silver, gold, tin, zinc, cadmium, or lead. Organic acid salts, oxides, etc. can be used. As a carrier,
Various metal oxides such as alumina, silica, titania, and silica-alumina can be used, but alumina is particularly preferred, and among them γ-A1203, η-A720a, θ-AA
'z03 etc. are suitable. As for the catalyst composition, the ratio of palladium to support is 0.05 to 5% by weight, preferably 0.
．． The ratio of the co-catalyst component to palladium is O61-10 as the metal atomic ratio, preferably 0.
It is in the range of 5-8.

When selective hydrogenation of acetylene compounds in the C3-4 fraction is carried out using a palladium-metal salt or metal oxide solid catalyst, the catalytically active species is considered to be a palladium-metal salt complex, and the support is estimated to contribute to increasing the effective surface area. Even in the case of liquid phase hydrogenation, the reason why the catalyst activity gradually decreases is thought to be that polymers and oligomers produced from diene and acetylene adhere to the active sites and reduce the effective surface area.

According to the present invention, the catalyst can be easily regenerated by heating the catalyst whose activity has decreased at high temperature in air and then reducing it with hydrogen or re-supporting the metal salt after hydrogen reduction, which is an interesting fact. In other words, it is presumed that it is difficult to regenerate the catalytic active species that were once formed because they are destroyed by heating and treatment in air, but contrary to expectations, new active species are formed by the treatment. , it is thought that regeneration will become possible.

The type, content, and generation mechanism of active species formed by the palladium-metal salt solid catalyst, as well as the content and generation mechanism of active species newly formed by this treatment, are unknown.
Its regeneration effect is extremely remarkable. Alternatively, the fact that there are cases in which the regenerated catalyst outperforms the fresh palladium-metal catalyst indicates that the former and the latter have different active species.

When performing the regeneration of the present invention, the heating temperature in air or oxygen-containing inert gas is 150 to 500°C, preferably 200°C.
-400°C. Furthermore, the heat-treated catalyst is reduced with hydrogen at a temperature of 50 to 300°C, preferably l0
It is in the range of 0-200°C. When re-supporting the metal salt after hydrogen reduction, the amount relative to palladium is O91 to
10. It is preferably in the range of 0.5 to 8, and the catalyst drying temperature after reloading is 50 to 200°C, preferably 100 to 1
The temperature range is 50°C.

According to the method of the present invention, there is an excellent advantage that any acetylene removal rate butadiene loss of the catalyst whose activity has decreased can be regenerated.

Hereinafter, the method of the present invention will be explained in more detail by showing typical examples. However, these are just examples;
It goes without saying that the present invention is not limited to these.

(1) Raw material hydrocarbon butanes 67, t% Dibutenes 22.6 Isobutene 25.9 13-butadiene 438 12-butadiene 0.1 Ethylacetylene 0.2 Vinyl acetylene 0.7 Methylacetylene Trace amount of propadiene Trace amount (2) Hydrogen Conditions Temperature: 20°C; Pressure: 10 kg/crlG; H2 molar ratio: 5; LH8V 15hr' (3) Catalyst (after 1500 hours of use) 9d content (relative to An)
20 a) = 0.35% (4) Catalyst Regeneration Method After heating in air at 300° for 5 hours, it was reduced in hydrogen for 15 hours for 6 hours.

F Pi> P Then pd (CH3COO)2 -/pd atomic ratio =
Reloaded at 2 equivalents and dried at 105° for 16 hours.

By performing the above regeneration on the catalyst with decreased activity, (1), (
The table shows the results of hydrogenation removal reaction of C4 acetylenes using the C4 fraction and hydrogen conditions corresponding to 2).

Example 2 The same regeneration as in Example 1 was carried out except that pd (CH3COO)2 was not re-supported, and the same hydrogenation reaction was carried out.

The results are shown in the table.

Comparative Example 1 Example 1 for a catalyst with reduced activity without any regeneration
A hydrogenation reaction was carried out in the same manner. The results are shown in the table.

reaction results Patent applicant: Showa Denko Co., Ltd.

Claims (1)

[Claims] Palladium metal as carrier and copper, gold, silver, tin as promoter,
In a method for regenerating a catalyst for selective hydrogenation of an acetylene compound in an olefin in which at least one K of an inorganic acid salt, an organic acid salt, or an oxide of zinc, cadmium, or lead is supported, a catalyst having decreased activity is used. A method characterized by hydrogen reduction after high-temperature heating in air or an oxygen-containing inert gas atmosphere, or re-supporting and regenerating the co-catalyst component after hydrogen reduction.