JPH059372B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for recovering faujasite-type zeolite having excellent thermal stability. More specifically, for example, phosiasite that has been thermally stabilized by high-temperature calcination treatment is brought into contact with an ammonium salt solution for ion exchange, and after adjusting the pH of the resulting slurry to within a certain range, It is an object of the present invention to provide a method for efficiently recovering forge site in an extremely short period of time. Zeolite is a crystalline condensed aluminosilicate that is well known as a molecular sieve having a three-dimensional network structure of silica-alumina tetrahedrons, and there are naturally occurring products and synthetic products. There are many types of zeolites depending on the cation species, silica/alumina ratio, and condensation type, and they are used as various catalysts, adsorbents, and drying agents. Some of these zeolites are used in the production of hydrocarbon additive catalyst compositions, which typically consist of zeolites and inorganic oxides such as silica-alumina, clay, bauxite, and silica-magnesia. Produced as a mixture with matrix material, containing approximately 5% to 50% zeolite component
contains. Among the zeolites used as a component of the catalyst composition, a catalyst composition in which the zeolite component is a phodiasite type zeolite is said to have particularly excellent properties as a fluid catalytic cracking solvent. . Now, zeolate, which is used as a component of the catalyst composition, is usually a synthetic zeolite because of its purity and compositional uniformity, and synthetic phasiasite is generally a synthetic zeolite that is an ion-exchangeable alkali metal or alkaline earth zeolite. In a form containing metal,
It is most commonly synthesized as the sodium form. When using faujasite as a component of a catalyst composition, it does not show catalytic activity if the cation is an alkali metal, so the alkali metal component in faujasite is ion-exchanged to form hydrogen , ammonium type, or polyvalent metal type, especially rare earth metal type faujasite. The main problem with the use of catalyst compositions containing such hawkiasite as fluid catalytic cracking catalysts is the general lack of stability of the crystal structure of hawkiasite. In other words, the fluid catalytic cracking catalyst is used repeatedly in a repeated cycle of reaction and regeneration. The phagiasite in the catalyst does not lose its crystallinity and becomes an amorphous substance, losing its catalytic activity and significantly reducing its utility value. The reason for this is said to be the instability of the crystal structure of faujasite. For this reason,
The current situation is that it is desired to develop a fauziasite that does not lose its catalytic activity even in such an environment. In response to this demand for thermal stabilization, various methods for producing phosiasite have been developed. For example, (1) phosiasite with a silica/alumina ratio of about 3.5 to 7 is ion-exchanged with a solution of nitrogen base to reduce the alkali metal content to about 1.5 to 4 wt.
% and then calcining at a temperature of 704 to 871 degrees (Special Publication No. 1973-20386), (2) Ion exchange rate is 50%.
More than 343 ammonium type phosiasites
A method of calcining in humid air at 648℃ followed by contact with a 5% or more water vapor atmosphere at a temperature of 427 to 816℃ (Japanese Patent Publication No. 44-31948), (3) ion exchange of phosiasite with an ammonium salt solution. The rare earth metal content is 0.3 to 10 wt% as oxide, and the temperature is 371 to 871℃.
Method of calcination, (Special Publication No. 47-23799), (4)
A method of calcining ammonium-sodium type phasiasite containing about 0.6 to 5 wt% sodium as Na ₂ O at a temperature of about 316 to 899 °C in the presence of at least about 0.014 Kg/cm ² of water vapor (Tokuko Showa) 57−
16925) etc. All of the hawkiasites produced by these methods are based on the knowledge that the alkali metal content of the hawkiasite affects its thermal stability. That is, as the alkali metal content increases, the thermal stability of phasiasite decreases, so ion exchange treatment is further carried out until the alkali metal content becomes about 1 wt% or less. For example, the above-mentioned special public service
Calcined faujasite with an alkali metal content of 1.5 to 4 wt%, produced by the method described in No. 20386, is further ionized, typically in an aqueous solution of ammonium sulfate, until the alkali metal content is preferably less than 0.4%. After the exchange treatment, phasiasite, which has a very low alkali metal content and excellent thermal stability, is separated from the resulting slurry by filtration or centrifugation. However, it has been found that when phasiasite is a fine particle, this separation requires a long time and involves difficulties in salt handling, which limits production capacity and poses a major problem in industrial production. In other words, in the experience of the present inventors, there is not much of a problem during small-scale separation processing in the laboratory, but when processing a large amount of slurry, as separation continues, the conventional operation We learned that solid-liquid separation is impossible using this method. The inventors of the present invention have made extensive studies to solve this industrially significant problem, and as a result, have found an extremely simple method and have completed the present invention. In other words, the present invention further ion-exchanges thermally stabilized phosiasite with an ammonium salt, adjusts the pH value of the slurry within the range of 1.5 to 2.8, and then separates phosiasite from the slurry. There is a method for collecting fauzia site that is characterized by: Next, the present invention will be explained in more detail. In the present invention, the thermally stabilized phosiasite is, for example, zeolite obtained by heat-treating phosiasite whose alkali metal content has been reduced to about 5 wt% or less at a temperature of about 600° C. or higher. The present invention
First, heat-stabilized phosiasite is mixed with an ammonium salt solution to form a slurry, which is then subjected to ion exchange treatment. Examples of the ammonium salt include ammonium chloride, ammonium sulfur, ammonium nitrate, and ammonium acetate, among which ammonium chloride and ammonium sulfate are particularly preferred. Then, the ion exchange step is carried out from 25 to
It is carried out at a temperature of 100°C, preferably 60 to 100°C, for about 0.5 hours or more, preferably 2 hours or more. The separation of phasiasite from the slurry that has undergone ion exchange can be carried out by either a batch method or a continuous method, but it is important to reduce the pH of the slurry to 1.5 to 2.8 before starting the phasiasite separation operation. It is necessary to adjust it within the range. The adjustment is carried out by adding an acid. Normally, the pH value of the slurry to which no acid is added is determined by the type of ammonium salt, the composition of thermally stabilized faujasite,
Although it varies depending on the slurry concentration of the salt and the phasiasite, it is within the range of about 3 to 5, but in the present invention, the PH value can be adjusted to within the range of 1.5 to 2.8. This is a very important point of the present invention. If the pH value is less than 1.5, the crystal structure of phasiasite collapses, and if it exceeds 2.8, the separation property deteriorates, which is not desirable. Acids that can be used in the present invention include mineral acids, phosphoric acid,
and water-soluble organic carboxylic acids, including hydrochloric acid,
Sulfuric acid and nitric acid are particularly preferred acids. Moreover, it is preferable that the acid consists of the anion part of the ammonium salt in the slurry. For example, if the ammonium salt is aluminum chloride, the acid is preferably hydrochloric acid. Furthermore, the acid is 1 to 15
It is preferable to add it to the slurry as an aqueous solution of a specified concentration, because if an excessively concentrated acid solution is used, the crystal structure of phasiasite will collapse at the contact area between the slurry and the acid.
Also, using too dilute an acid solution may result in
This is because in order to obtain the PH value, the amount added is large, which unnecessarily increases the amount of slurry and deteriorates the separation efficiency. Further, the acid may be added at any time before the separation step, but preferably 0.1 to 6 hours before the start of the separation operation. The present invention will be specifically explained by showing preferred examples below. Note that the present invention is not limited to the examples. Example 1 Synthetic sodium-type phagiasite with a silica/alumina ratio of 5.2 was ion-exchanged using an aqueous ammonium chloride solution to reduce the Na ₂ O content.
3.3wt% ammonium-sodium type faujasite was obtained. Next, this faugiasite was calcined in a Matsufuru furnace at 800°C for 2 hours, and cooled to obtain thermally stabilized faugiasite. Next, 100g of this faujasite, 250g of ammonium chloride
A slurry consisting of 730 g of pure water and 730 g of pure water was prepared and maintained at 80° C. for 4 hours while stirring. Next, 36% hydrochloric acid was added to this slurry, and the slurry was held for an additional 30 minutes to adjust the pH value to 2.4. This slurry was used as a separation test slurry, and 100ml of it was
was subjected to the separation test described below. The separation test was performed using a leaf tester equipped with a filter having a polypropylene filter cloth (PF660 manufactured by Nakao Rofuku Co., Ltd.) with a filtration area of 28 cm ² and a vacuum degree of 500 mmHg.
Suction filtration was carried out under the following conditions. The time from the start to the end of filtration of 100 ml of the slurry for the separation test was defined as the "filtration time". Also, immediately after filtration
The time from the start of washing by pouring 100 ml of 60°C warm water onto the faugiasite cake on the filter cloth until the end was defined as the "washing time". The following examples were also conducted using this separation test. The results are shown in Table-1. Example 2, Comparative Example 1 A slurry was prepared under the same conditions as Example 1 except that the pH was adjusted to 1.7 and 3 in Example 1,
A separation test was conducted. The results are shown in Table-1. Comparative Example 2 A slurry was prepared under the same conditions as in Example 1, except that the pH was not adjusted, that is, no acid was added, and a separation test was conducted. In addition, the slurry
The pH was 3.4. The results are shown in Table-1. Example 3 Phausiasite thermally stabilized in Example 1
100g, ammonium chloride 250g, and pure water 730g
30 minutes after heating to 80℃, add 10N sulfuric acid and hold for 4 hours to adjust the pH.
A slurry was prepared and a separation test was conducted under the same conditions as in Example 1, except that the ratio was adjusted to 2.3. The results are shown in Table-1. 18 Example 4 A slurry consisting of 100 g of heat-stabilized phasiasite obtained under the same conditions as Example 1, 250 g of ammonium chloride, and 730 g of pure water was prepared and kept at a temperature of 80° C. for 4 hours with stirring. The entire amount was filtered and washed with ₁₃ portions of pure water to obtain a forujasite wet cake. A slurry of 1080 g consisting of the entire wet cake, 250 g of ammonium chloride, and pure water was prepared and maintained at a temperature of 80° C. for 4 hours with stirring. Next, 36% hydrochloric acid was added to this slurry and held for 30 minutes to adjust the pH to 2.3. This slurry was used as a slurry for a separation test, and 100 ml of the slurry was used for a separation test. The results are shown in Table-1. Example 5 A slurry was prepared under the same conditions as in Example 4, except that the pH of the slurry to be separated was adjusted to 1.7, and a separation test was conducted. The results are shown in Table-1. Comparative Example 3 A slurry was prepared under the same conditions as in Example 4, except that the pH was not adjusted, that is, no acid was added, and a separation test was conducted. Note that the pH of the slurry was 3.5. The results are shown in Table-1. Table 1 shows that the method of the present invention greatly improves the efficiency of separating phodiasite from a slurry obtained by ion-exchanging thermally stabilized phodiasite with an ammonium salt.

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Claims (1)

[Claims] 1. Bringing thermally stabilized hawkiasite into contact with an ammonium salt solution to perform ion exchange, adjusting the pH of the resulting slurry to 1.5 to 2.8, and then obtaining hawkiasite from the slurry. A method for collecting forgeside, which is characterized by: 2. The method according to claim 1, wherein the pH is adjusted to 1.5 to 2.8 using an acid.