JPH02119938A - Ethylene remover, production thereof and synthetic resin film for removing etylene - Google Patents

Abstract

PURPOSE:To considerably enhance ethylene removing ability per unit weight by wrapping vegetables and fruits with a film of synthetic resin kneaded with a catalyst obtd. by supporting palladium on a silica alumina carrier and using the catalyst for ethylene remover. CONSTITUTION:Palladium is supported on a silica alumina carrier having 5/1-1/5 weight ratio of silica/alumina by 0.01-2.0wt.% of the amt. of the carrier in the form of a compd. or a mixture of two or more kinds of compds. selected among inorg. acid salts of palladium and ammonium complex salts of them. At this time, the palladium compd. is impregnated into the carrier under basic conditions using 1-3wt.% aq. ammonia soln. and the impregnated carrier is calcined at 300-750 deg.C to obtain an ethylene remover. The freshness of vegetables and fruits can be maintained by wrapping with a film of synthetic resin (thermoplastic resin) kneaded with 0.05-2.0wt.% of the ethylene remover basing on the amt. of the resin. The ethylene remover does not color the resin or affect the transparency of the resin.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ethylene removal agent, a method for producing the same, and a synthetic resin film for ethylene removal into which the removal agent is incorporated.

(Prior art) As is well known, fruits and vegetables constantly respire and transpire even after they are harvested, and the ethylene gas generated during this process acts on the fruits and vegetables as a ripening hormone, promoting their ripening and causing them to turn yellow. Causes phenomena such as softening, softening, and rotting.

Many ethylene adsorbents are being researched to remove this ethylene and maintain the freshness of fruits and vegetables.

For example, there are methods that perform physical adsorption using activated carbon or natural zeolite. Furthermore, research has been conducted to improve the adsorption ability of these substances, such as by treating carbonaceous molecular sieves with 4 to 6 carbon atoms with bromine (Special Publication No. 3914/1982), and by treating natural zeolites with potassium permanganate. There is (Special Publication No. 61-17461). Also, activated carbon is impregnated with palladium chloride under hydrochloric acid acidity (Special Publication Publication No. 1986-2).
5340), and activated carbon treated with potassium bromate or sodium bromate in the presence of sulfuric acid water (Japanese Patent Publication No. 61-26415, Japanese Patent Application Laid-Open No. 60-190231).

(Problems to be Solved by the Invention) However, when using physical adsorption such as activated carbon or natural zeolite, the adsorbed ethylene gas is easily desorbed by moisture or the like. For this reason, various ethylene adsorption/modification agents that convert adsorbed ethylene into other substances have been developed and patent applications have been filed. Among these representative products, carbonaceous molecular sieves treated with bromine have a nominal ethylene adsorption capacity of 4.
．． It is low at 2ml/g and is made from harmful substances such as bromine water and bromine gas.

In those using potassium permanganate, potassium permanganate is leached in the presence of moisture, which is harmful in terms of food hygiene, and its removal capacity is as low as 1.6 ml/g. Activated carbon impregnated with palladium chloride under acidic conditions with hydrochloric acid has an extremely low ability to remove ethylene. Furthermore, activated carbon treated with potassium bromate or sodium bromate in the presence of sulfuric acid water has a nominal ethylene adsorption capacity of 29. M! /g, which is the largest value among conventional products.

However, since these ethylene removing agents have a small ethylene removing ability in order to be kneaded into the film, it is necessary to knead a large amount of the ethylene removing agent into the film, which is actually very difficult.

Furthermore, the synthetic resin film kneaded with ethylene removing agent is
From the viewpoint of marketability, it is preferable to have good transparency and no coloring so that the freshness of fruits and vegetables can be confirmed from the appearance. From this point of view, when activated carbon that has been chemically treated is kneaded into a film, there may be problems with the coloring and transparency of the film, and there are concerns that chemical substances may be leached from the film.

The purpose of the present invention is to develop a ceramic catalyst that has a large ethylene removal ability and that removes ethylene by adsorption and auto-oxidation at room temperature, rather than by mere physical adsorption of ethylene. The aim is to improve the ability to remove ethylene per unit time and thereby realize a useful kneaded film.

(Means for Solving the Problem) As a result of intensive research in accordance with the above viewpoints, the present inventors discovered that a catalyst in which palladium is supported on a silica alumina carrier is excellent as an ethylene removal agent, and the present invention has been developed. It has been completed.

That is, the present invention is an ethylene removing agent characterized by comprising palladium supported on a silica alumina carrier.

The silica alumina carrier preferably has a weight ratio of 5/1 to 11.
It has a silica/alumina ratio of 5, more preferably a silica/alumina ratio of 371 to 1/3 by weight.

The supporting ratio of palladium is preferably 0.01 to 2.0% by weight, more preferably 0.1 to 0.5% by weight based on the silica alumina carrier.

The present invention also relates to a method for producing the above-mentioned ethylene removing agent, which is characterized by impregnating a palladium compound into a silica-alumina carrier under ammoniacal basic conditions and finally firing. At that time, the ammonia basic conditions are 1 to 3
Preferably, % by weight of aqueous ammonia is used. Also,
It is preferable that the palladium compound is one type of compound selected from the group consisting of palladium inorganic acid salts and ammonium complex salts thereof, or a mixture of two or more types of compounds. The firing temperature is preferably 300 to 750'c.

Furthermore, the present invention is a synthetic resin film for removing ethylene, characterized in that the above-mentioned ethylene removing agent is mixed therein.

The mixing ratio of the ethylene removing agent to the synthetic resin is 0.
The amount is preferably 0.05 to 2.0% by weight. Further, as the synthetic resin, a thermoplastic resin is preferable, and a polyolefin is more preferable.

The present inventors have discovered that silica (S 1
A detailed study was conducted on the ratio of Ox) and alumina (Altos). For example, for silica, a hydrogel can be produced by dropping sulfuric acid water into an aqueous sodium silicate solution. For alumina, a hydrogel can be produced by adding ammonia to an aqueous aluminum nitrate solution or by dropping sulfuric acid water into sodium aluminate. After thoroughly washing these hydrogels and draining them by suction filtration, they were mixed in a ball mill, but the mixing method is not limited to this. Further, as a method for preparing silica alumina gel, a method by coprecipitation can also be used.

Next, the compatibility of the catalyst as a carrier is determined by Sin, /Aρ20
．． As a result of examining the mixing ratio in the range of 1071 to 1/10 by weight, it was discovered that a weight ratio of 571 to 175 (preferably 371 to 1/3) is preferable as a carrier. Outside this range, there was no significant difference from those using silica or alumina alone as a carrier, and the performance as a carrier was very low.

The silica alumina gel obtained by mixing is shaped into an appropriate shape, for example, a diameter of 4 m, length of 4 m, to facilitate the subsequent process.
a After forming into cylindrical pellets, they are dried and fired. The firing temperature of the carrier is 2QO''c to 750'C without any problem, and preferably 350 to 450'C.

On the other hand, regarding palladium to be supported, we investigated commercially available palladium chloride, palladium nitrate, palladium sulfate, and their ammonia complex salts, and found that the best method was to impregnate palladium salt or ammonia complex salt from a basic aqueous solution of ammonia water. I got it. The amount of palladium supported is preferably 0.01 to 2.0% by weight, more preferably 0.1 to 0.5% by weight, based on the carrier. The reason why this range is preferable is that as the amount of palladium supported increases, its ability as an ethylene removal agent gradually increases, but the ethylene removal effect does not increase as the amount of palladium used increases, and the efficiency of palladium usage increases. This is because it decreases.

The concentration of the ammonia water used was investigated in the range of 0.01 to 25%, and was found to be preferably in the range of 1 to 3%. If the ammonia concentration is lower than this, it is difficult to dissolve palladium chloride, and even if the concentration is higher than this, not only is there no improvement in the performance of the ethylene removal agent, but many neutralizing agents are used due to the problem of wastewater pollution. Because you need it.

The catalyst supporting palladium is washed with pure water if necessary, and dried at 100°C to 150°C. There is no problem with the firing temperature of the catalyst in the range of 300°C to 750°C.

It has been found that the present invention greatly improves the ability to remove ethylene per unit weight, and that most of the adsorbed ethylene is autooxidized and converted into substances other than ethylene. In addition, by using a ceramic high-performance ethylene remover such as the product of the present invention, it has a characteristic that is not found in conventional products, when it is crushed into an appropriate size according to the required thickness of the film and kneaded into the film. It is expected that the freshness-preserving film for fruits and vegetables can be used without problems with coloration or transparency, and without the risk of chemical substances leaching from the film.

The raw material synthetic resin that can be used in producing the synthetic resin film incorporating the ethylene removing agent of the present invention includes thermoplastic resins, particularly polyolefins such as polypropylene and polyethylene. However, care must be taken during film formation as the additives contained in the film may poison the ethylene removal agent.

(Example) Hereinafter, the present invention will be specifically explained based on Examples.

Example 1 500 g of sodium silicate solution (SiO,/Na20 (weight ratio) -2.06 to 2.31) was dissolved in pure water to prepare solution No. 31. 3N sulfuric acid was added dropwise to this solution over 1 hour while stirring to give a final pH of 1. A sufficient amount of silica gel is generated, washed with water, and then suction-filtered to obtain a gel.

Dissolve 500 g of sodium aluminate (A It /N a OH (molar ratio) - 0, 56) in pure water to make a 7β solution.

Add 5N sulfuric acid dropwise to this for 1 hour while stirring to make the final p.
Let H=9. - After the aluminum hydrogel is precipitated and decanted at night, it is thoroughly washed with aqueous ammonia having a pH of 9. This is filtered with suction to obtain a gel.

The above aluminum and silica hydrogel is SiO□/A
1203 in a predetermined weight ratio, kneaded using a ball mill, formed into pellets with a diameter of 4 mm and a length of 41 m, and dried at 100° C. for 2 hours. Thereafter, it is calcined at 350° C. for 4 hours to obtain a catalyst carrier.

0.1% by weight in terms of palladium for 10g of this carrier
Weigh palladium chloride corresponding to , dissolve it in 100 ml of 1% by weight ammonia water in a 200 ml Erlenmeyer flask, and soak the carrier overnight in this solution. After thoroughly washing with pure water, it is dried at 100°C for 2 hours and fired at 350°C for 4 hours.

The ability of the ethylene removing agent was measured by the following method. 1 g of the ethylene removing agent prepared by the above method is placed in a sealed container having an internal volume of about 130 cm. Ethylene gas 45- was added to this, and the decreasing amount of ethylene was monitored using a gas chromatograph.

The airtight container was left in a constant temperature room at 25 ± 0.5°C, and the decreasing amount of ethylene was calculated using standard ethylene gas (manufactured by Gascro Industries, purity 99.5%) for each n'Mt.
A calibration curve was created at 100°C, and the amount of residual gas in the sealed container was determined and subtracted from the amount added.

Gas chromatography conditions for analysis were Porapak Q 80/100 mesh, caliber 3.
mm, length 3 m −.

The test was carried out using a column temperature of 150°C, FID, and a sample size of 0 and 2 ml.

Table 1 shows S i Oz / A j! Palladium was added to a carrier with varying mixing ratios (weight basis) of zch.
The figure shows the ethylene removal ability of a catalyst prepared by impregnating it with 1% by weight 24 hours after addition of ethylene.

Table 1 (Values are ethylene removal capacity crab mf/10g catalyst.) Table 2
is the change in ethylene removal over time when the amount of palladium impregnated into a carrier with a SiO□/AJ203 mixing ratio of 1/1 (weight basis) was varied from 0.01% by weight to 2.0% by weight. This shows the situation.

Table 2 (Values are ethylene removal capacity m1/log catalyst) Example 2 Weight ratio of SiO□/Aj2203 prepared in Example 1 1
An ethylene removing agent prepared by impregnating 0.1% by weight of palladium on a 1/1 carrier was pulverized using a ball mill, sifted, and the passed product was mixed with polypropylene and polyethylene.
A film having a thickness of 35 μm was prepared by kneading the mixture by weight%.

The ethylene removal ability was measured by the following method. 20 g of a film kneaded with a catalyst having the above particle size is placed in a closed container having an internal volume of about 600 mf. Add ethylene gas to this
Q ml was added and the decreasing amount of ethylene was monitored using a gas chromatograph. The analysis conditions and the method for calculating the amount of reduced ethylene are the same as in Example 1.

The results are shown in Table 3.

(The numerical value is ethylene removal capacity crab ml/10g catalyst) (Effects of the invention) The ethylene removal capacity per unit weight has been significantly improved by the present invention.

In addition, by using a ceramic high-performance ethylene removal agent like the product of the present invention, it has characteristics not found in conventional products.
It can be kneaded into synthetic resin films, and is expected to have functions such as preserving the freshness of fruits and vegetables.

Claims (13)

[Claims] (1) An ethylene removal agent characterized by comprising palladium supported on a silica alumina carrier. (2) Claim 1, wherein the silica-alumina support has a silica/alumina ratio of 5/1 to 1/5 by weight.
Ethylene removal agent as described. (3) The ethylene removing agent according to claim 1, wherein the silica-alumina carrier has a silica/alumina ratio of 3/1 to 1/3 by weight. (4) The ethylene removing agent according to any one of claims 1 to 3, wherein the supporting ratio of palladium is 0.01 to 2.0% by weight based on the silica alumina carrier. (5) The ethylene removing agent according to any one of claims 1 to 3, wherein the supporting ratio of palladium is 0.1 to 0.5% by weight based on the silica alumina carrier. (6) The method for producing an ethylene removing agent according to any one of claims 1 to 5, characterized in that a silica alumina carrier is impregnated with a palladium compound under ammoniacal basic conditions and finally calcined. (7) The production method according to claim 6, wherein the ammonia basic condition comprises using 1 to 3% by weight of aqueous ammonia. (8) The palladium compound is selected from the group consisting of inorganic acid salts of palladium and ammonium complex salts thereof.
The manufacturing method according to claim 6 or 7, wherein the method is a compound of a species or a mixture of two or more compounds. (9) Claims 6 to 8 that the firing temperature is 300 to 750°C.
The method for producing an ethylene removing agent according to any one of the above. (10) A synthetic resin film for removing ethylene, characterized in that the ethylene removing agent according to any one of claims 1 to 5 is mixed therein. (11) The synthetic resin film according to claim 10, wherein the mixing ratio of the ethylene removing agent is 0.05 to 2.0% by weight based on the synthetic resin. (12) The synthetic resin film according to claim 10 or 11, wherein the synthetic resin is a thermoplastic resin. (13) The synthetic resin film according to claim 10 or 11, wherein the synthetic resin is a polyolefin.