JPH04131136A - Regeneration of catalyst for preparing allyl acetate - Google Patents

Abstract

PURPOSE:To effectively regenerate a palladium supported catalyst by washing the palladium supported catalyst used in reaction with water or a 6 or less C org. solvent having a b.p. of 70 deg.C or higher under atmospheric pressure. CONSTITUTION:The palladium supported catalyst used in reaction preparing allyl acetate from propylene, acetic acid and oxygen in a gaseous phase is washed with a solvent. As the solvent used in washing, one capable of removing resin, resinous matter an alkali metal acetate and an alkaline earth metal acetate on the surface of palladium without imparting a change to the form of palladium is pref. and pure water or a 6 or less C org. solvent having a b.p. of 70 deg.C or higher, for example, org. acids such as acetic acid or propionic acid, esters such as ethyl acetate or butyl acetate or alcohols such as ethanol or propanol is used and the washing due to pure water is especially pref. Washing is pref carried out at about 15-40 deg.C. By this method, the palladium supported catalyst can effectively be regenerated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a method for regenerating a palladium-supported catalyst, and in particular a method for producing allyl acetate from propylene, acetic acid and oxygen using a palladium-supported catalyst in the gas phase. relates to a method for regenerating a palladium-supported catalyst whose activity has decreased during use.

[Prior art 1] A method for producing allyl acetate by reacting propylene, oxygen and acetic acid in the gas phase using a palladium catalyst is known [for example, Japanese Patent Publication No. 44-29046, Japanese Patent Publication No. 47-1]
2335, Special Publication No. 47-38415, Special Publication No. 48-
10761, Special Publication No. 50-5685, etc.]. These methods use palladium as the main catalyst and at least one alkali metal or alkaline earth metal and gold, copper, molybdenum, cadmium, lead, vanadium, bismuth, chromium, tungsten, manganese, iron, ruthenium, rhenium, etc. This is carried out using a catalyst prepared by using a metal as a promoter and supporting these catalyst components on alumina, silica, activated carbon, pumice, titanium oxide, or the like.

However, this type of catalytic reaction has the problem that as the reaction time increases, the activity gradually decreases and the amount of allyl acetate produced decreases.

[Problems to be Solved by the Present Invention] In the above production method, a catalyst in which palladium is supported as a king catalyst on the above-mentioned carrier is used, but the catalytic activity of this palladium-supported catalyst deteriorates over a long period of time ( The yield of allyl acetate gradually decreases with the reaction time, and the selectivity of allyl acetate also decreases, leading to a decrease in the yield of allyl acetate. The purpose of this invention is to provide a method for regenerating catalysts that is efficient and simple.

[Means and effects for solving the problem 1 The inventors have
As a result of extensive research to provide a method to effectively regenerate the palladium-supported catalyst used in the production of allyl acetate from propylene, acetic acid, and oxygen through a gas-phase reaction, the palladium-supported catalyst used in the reaction was The product washed in pure water or a solvent consisting of an organic compound having a boiling point of 70°C or more and a carbon number of 6 or less under normal pressure is dried, and if necessary, an acetate of an alkali metal or alkaline earth metal is added to this. The present invention was completed based on the discovery that a catalyst whose activity has decreased can be regenerated by supporting the catalyst.

The present invention will be explained in detail below.

In the present invention, first, the palladium-supported catalyst used in the method for producing allyl acetate by reacting propylene, acetic acid, and oxygen with allyl acetate in the gas phase is washed with an appropriate solution.

The solvent used for cleaning is preferably one that can remove Harz, resin compounds, and acetates of alkali metals and alkaline earth metals that coat the surface of palladium without causing any change in the form of palladium. or an organic solvent with a boiling point of 70° C. or higher and a carbon number of 6 or lower, such as organic acids such as acetic acid and propionic acid, or esters such as ethyl acetate, butyl acetate, and isopropyl acetate;
Alcohols such as ethanol, propatool, isopropyl alcohol, and butanol are used, and washing with pure water is particularly preferred.

Examples of cleaning methods include a flow method in which a column is filled with a catalyst and a solution is poured through the column for cleaning, and a batch method in which a solution and catalyst are placed in a beaker and stirred for cleaning.

The cleaning temperature is 5℃ to 70℃, which is effective.
In particular, washing at 15 to 40°C is preferred. If the temperature is below 5℃,
Because the cleaning effect on the catalyst surface is insufficient, and because the morphology of palladium is probably altered when the temperature exceeds 70°C, the increase in the active surface of palladium metal, which is determined by normal CO chemisorption measurements, is small. Recovery of activity is low. Also,
If the temperature exceeds 70°C, it is disadvantageous in terms of operation.

Next, after drying the washed catalyst, an acetate of an alkali metal or alkaline earth metal is supported on it and further dried. At that time, the mutual amount is 1 to 30wt%, especially 5 to 15w
t% is preferred. As the alkano metal or alkaline earth metal to be supported, salts of sodium, potassium, rubidium, cesium, calcium, strontium, barium, etc. are usually used.

Hot air drying, vacuum drying, natural drying, etc. are usually used as a method for drying the washed catalyst and after admixing the acetate of an alkali metal or alkaline earth metal.

In the method of the present invention, when producing allyl acetate by reacting propylene, acetic acid and oxygen, the reaction temperature is 1.
It is practically advantageous that the temperature is 00 to 200°C, preferably 140 to 170°C. From the viewpoint of equipment, it is practically advantageous for the reaction pressure to be between normal pressure and 30 atm, more preferably between 2 and 10 atm.

The gases supplied to the reaction system are essentially propylene, acetic acid, oxygen, and diluent gas. Propylene accounts for 5 to 50% by volume, preferably 10% by volume, based on the total amount of feed gas.
~40% by volume, and acetic acid from 5 to 20% by volume.
, preferably in an amount of 6 to 10% by volume, and oxygen is supplied to the reaction system in an amount of 3 to 15% by volume, preferably 5 to 10% by volume, respectively. Further, from the viewpoint of prolonging the catalyst life, the reaction may be carried out in the presence of an appropriate amount of water.

[Example 1 The present invention will be further explained below with reference to Examples.

Example 1 200 m°C of the catalyst used in the reaction was placed in a beaker, 200 m12 of pure water was added thereto, and the mixture was stirred and washed at room temperature.

Repeat this 3 times, drain the water from the catalyst, and put it in the dryer for 11 minutes.
Dry with hot air at 0°C for 20 hours. Next, 3 g of potassium acetate is taken, turned into a water-temperature liquid, and then impregnated into the dry catalyst to be supported. This is dried in a hot air dryer at 110° C. for 4 hours to obtain a regenerated catalyst. This catalyst was packed into a reaction tube, containing 30% propylene, 7% oxygen, 10.0% acetic acid,
A mixed gas containing 53.0% nitrogen was supplied at 42 N R, and the reaction was carried out under the conditions of a reaction pressure of 5 kg/crn'G and a reaction temperature of 160°C.

The results are shown in Table 1.

Example 2 The catalyst was regenerated in the same manner as in Example 1, except that ethyl acetate was used instead of water, and the allyl acetate synthesis reaction was carried out under the same conditions as in Example 1.

The results are shown in Table 1.

Example 3 In Example 1, except that acetic acid was used instead of water,
The catalyst was regenerated in a similar manner, and allyl acetate synthesis reaction was carried out under the same conditions as in Example 1. The results are shown in Table 1.

Example 4 The catalyst was regenerated in the same manner as in Example 1, except that the grade of water was changed to 5° C., and the allyl acetate synthesis reaction was carried out under the same conditions as in Example 1. The results are shown in Table 1.

Example 5 The catalyst was regenerated in the same manner as in Example 1, except that the water temperature was changed to 70° C., and the allyl acetate synthesis reaction was carried out under the same conditions as in Example 1. The results are shown in Table 1.

Example 6 In Example J, the catalyst was regenerated in the same manner as in Example J, except that rubidium acetate was used instead of potassium acetate, and the allyl acetate synthesis reaction was carried out under the same conditions as in Example 1. The results are shown in Table 1.

Example 7 The catalyst was regenerated in the same manner as in Example 1, except that strontium acetate was used instead of potassium acetate.
Allyl acetate synthesis reaction was carried out under the same conditions as in Example 1. The results are shown in Table 1.

Comparative Example 1 After once drying the catalyst used in the reaction, allyl acetate synthesis reaction was carried out under the same conditions as in Example 1. The results are shown in Table 1.

Table 1 [Effects of the Invention] By the method for regenerating a palladium-supported catalyst of the present invention, the palladium catalyst used in the production of allyl acetate was effectively regenerated, making it possible to obtain a highly active catalyst.

Claims (2)

[Claims] (1) In a reaction in which acetic acid, propylene, and oxygen are reacted in the gas phase using a palladium-supported catalyst to obtain allyl acetate, the catalyst used in the reaction is mixed with water or with a boiling point of 70°C or higher under normal pressure and a carbon number A method for regenerating a catalyst for producing allyl acetate, the method comprising washing with an organic solvent of 6 or less. (2) The regeneration method according to claim 1, wherein an acetate of an alkali metal or an alkaline earth metal is supported on the washed catalyst.