HU199750B - Process for producing zeolite mixture of na/k/pc + naa type from perlite - Google Patents

Abstract

The present invention relates to a process for producing a zeolite mixture of Na (K) Pf + + NaA from perlite. The process according to the invention is characterized by the use of a spray of naturally occurring SiO2 and A12O3 sources, and the Na and / or K-hydroxide content of the aqueous slurry is adjusted to between 5 and 20% by weight, preferably between 7 and 11% by weight. the slurry is aged at 10-70 ° C, preferably at 20-40 ° C for 8 to 48 hours, and the synthesis slurry is crystallized at 70 to 150 ° C, preferably at 85 to 130 ° C with constant stirring, and to the slurry containing Na (K) Pr zeolite and water glass, sodium aluminate is added in an amount such that the molar ratio of dissolved SiO2 / Al2O3 in the synthesis slurry is between 1.5 and 2.0, preferably 1.7 and 2.0 the slurry is aged at 10-70 ° C for 8 to 48 hours, then the pH of the synthesis slurry is adjusted to between 13.4 and 14.4 with sodium hydroxide and the synthesis slurry is 60-100. Crystallize at 75 ° C to 80 ° C and isolate the crystalline product. H U 199750 B Scope of the description: 4 pages without drawing -1-

Description

The present invention relates to a process for the preparation of a zeolite mixture of Na (K) P _c ++ NaA from perlite.

The term Na (K) used in connection with the zeolites as used herein and in the specification means that the particular zeolite contains only sodium ions or sodium ions and potassium ions as exchangeable cations.

The symbols "P _c " and "A" in the title of the invention, respectively, represent two types of zeolite of different structure. (NaP _c , or Na (K) P _c zeolite is also known as "phyllipsite").

It is known that various crystalline tectosilicates, including zeolites, can be prepared by reacting alkaline aluminate- and silicate-containing slurries under hydrothermal conditions, depending on the chemical composition, the temperature employed and many other factors that influence crystalline nucleation and growth. By appropriate choice of reaction parameters, it is possible to crystallize the thermodynamically metastable Na (K) X and Na (K) Y with the faujazite structure or the phosphatite structured thermodynamically stable Na (K) P _c . Allows the Na (R) Pr-type zeolite is exchanged and only the smallest "guest molecules ¹¹ uptake (water, ammonia, etc) is partially hydrated ions, enabling application for selective use.

Nos. 2,882,244 and 2,130,007 describe the synthesis of the most common zeolites Na (K) X and Na (K) Y. U.S. Patent Nos. 4,119,119 and 5,123,125, which use alkali-aluminum-silicate gels and high surface-area silica as starting materials. Because of the high cost of these starting materials, many processes have been developed for the production of zeolites from naturally occurring minerals containing silicon and aluminum.

For example, U.S. Pat. No. 3,185,544. U.S. Pat. No. 4,800,198 discloses that the Na (K) X type zeolite is prepared starting from metakaolin, while U.S. Pat. U.S. Pat. The synthesis of Na (K) X from metakaolin is still relatively expensive, and the process from Satintone does not result in a sufficiently pure product because a large portion of alumina remains unexplored.

In both cases, the formation of the Na (K) P _f type zeolite is a distraction because it contaminates the target product.

We have found that perlite, which occurs in nature in much greater amounts than kaolin, is favorable (8.5 and

Because of its SiO ₂ / Al ₂ O ₃ modulus (9.5), an ideal starting material is a zeolite of Na (K) P _c or zeolite mixtures containing it.

The invention is based on the discovery that when the slurry is stirred in the first step of the zeolite synthesis, Na (K) P _c zeolite is formed and a dilute water glass solution as an intermediate is formed. Further crystallization of this intermediate with specific reaction parameters gives a mixture of Na (K) P _c and NaA zeolites.

Discovered fact that when the perlite and sodium hydroxide (or sodium hydroxide and potassium hydroxide mixture) principally formed Na (K), P _c the reaction mixture containing zeolite A and sodium silicate, sodium aluminate is added and the amount of added sodium aluminate, and temperature is kept within certain limits. A mixture of Na (K) Pc + - (- NaA) zeolites is formed which can be used directly in typical applications of these types of zeolites, such as carriers, adsorbents, etc. without separation of the components.

The present invention therefore relates to a process for the preparation of a mixture of Na (K) Pc-NAA type zeo starting from an aqueous slurry comprising naturally occurring sources of SiO ₂ and Al ₂ O ₃ , sodium hydroxide, water soluble sodium salt and / or water soluble potassium salt.

The process according to the invention is characterized in that perlite is used as a naturally occurring source of SiO ₂ and Al ₂ 0 ₃ and that the Na and / or K hydroxide content of the aqueous slurry is

5 to 20% by weight, preferably 7 to 11% by weight, the slurry is aged (aged) for 10 to 70 ° C, preferably 20 to 40 ° C for 8 to 48 hours, and the slurry is then aged after constant stirring, it is crystallized at 70-150 ° C, preferably 85-130 ° C, and then sodium aluminate is added to the slurry containing the Na (K) Pr type zeolite obtained in the first step and the water slurry in such a way that dissolved SiO ₂ / Al ₂ O ₃ molar ratio

1.5 to 2.0, preferably 1.7 to 2.0, the slurry is aged at 10-70 ° C for 8 to 48 hours and then the pH of the synthesis slurry with sodium hydroxide 13, 4 to 14.4 and the synthesis slurry is crystallized at 60-100 ° C, preferably 75-80 ° C.

After 3 to 6 hours, the crystalline product is separated from the mother liquor.

In the process according to the invention, it is expedient to use, as a starting material, expanded perlite having at least 90% by weight of particles having a size of less than 5 µm. Particularly preferred is, for example, the product "Perfii" (manufactured by Koszig V., Nyírtelek)

In order to accelerate crystal nucleation, the synthesis slurry is maintained at 10 to 70 ° C, preferably 20 to 40 ° C, for 8 to 48 hours, preferably 8 to 24 hours, prior to crystallization. This operation is hereinafter referred to as "aging."

In the process, the product, a zeolite mixture of the Na (K) Pr + -) - NaA type, is filtered off from the mother liquor by filtration. The Na and / or K hydroxide-containing mother liquors can be recycled to the synthesis mixture.

If desired, the zeolites or zeolite mixtures prepared according to the invention can be converted into zeolites containing other cations (e.g., Ca ²⁺ , Co ²⁺ , etc.) by ion exchange.

All process variants of the present invention are characterized by the presence of impurities present in the perlite other than the SiO ₂ , Al ₂ O ₃ and R ₂ O (R = alkali metal) components (e.g. Fe ₂ O ₃ , MgO, TiO ₂ , etc.) and even SiO ₂ quartz. phase remains partially unexplored under the operating conditions used. The mother liquors formed during crystallization are pure, free of alkaline earth metal or other metal contamination, and are therefore well suited for further processing.

Zeolites of the Na (K) P _c + -) - NaA type obtained according to the invention can be used, for example, as catalyst components (e.g. cracking of gas oils), as carriers for pesticides and animal feeds, as ion exchange agents and as drying agents.

_C P Na (K) type zeolite to hygroscopicity reaches 18% by weight, which was less than 4% lower than for the commonly used drying NaA zeolite. The Na (K) P _c type zeolite, on the other hand, can only bind water in its structure because the permeable gases (with the exception of argon) cannot penetrate the narrow pores of the zeolite. Therefore, the zeolite Na (K) P _c can be used alone in a narrower field.

The NaA (K) P _c + NaA zeolite mixture formed in the process is predominantly Na-type (65-75 wt%) and therefore has only a few percent of the water absorption capacity of the NaA-type zeolite and can be replaced almost equivalently.

An important advantage of the process according to the invention is that it enables the utilization of a large amount of cheap perlite complexes of relatively constant composition which are available worldwide and result in valuable synthetic zeolites which can only be produced in a much more complicated or costly manner by other methods.

The following examples illustrate the process of the invention:

100 g of anhydrous Perfil contain 1.22 moles of SiO ₂ , 0.125 moles of Al ₂ 0 ₃ and 0.147 moles of Na ₂ O + K ₂ O.

95% by weight of Perfii granules have a particle size of less than 25 µm.

To 300 g of Perfil was added a solution of 112.9 g (1.411 mol) of sodium hydroxide in 977 g of water. The slurry was ground in a shaker ball mill for 4 hours, then the steel balls were removed and the slurry was autoclaved. The slurry was aged for 24 hours at room temperature and then crystallized with vigorous stirring at 100 ° C for 8 hours.

The crystalline slurry formed was cooled to 60 ° C and with vigorous stirring, 575.5 g of concentrated aqueous sodium meta-aluminate solution (Al ₂ O ₃ : 1.116 mol, Na ₂ O: 992 mol, water: 18.8 mol) ) is added. The autoclave was sealed and the slurry was stirred for 5 hours at 88 ° C. The solid crystalline material is then filtered through a G3 glass filter and washed with hot distilled water until the pH of the washer fluid reaches

10.5. The solid was dried at 90 ° C.

596 g of almost white product was obtained containing zeolite NaA and 68% NaP _f type NaA zeolite based mixtures and X-ray diffraction analysis.

The product has a water-binding capacity of 20% by weight, as a drying agent.

Example 2

Example 1 is repeated, but using Perfit as a starting material containing 3.0 wt% K ₂ O at the expense of volatile matter.

Aging is carried out at 40 ° C for 30 hours. The crystallization was carried out for 10 hours.

The resulting slurry Na (K) comprises zeolite P _f and water glass.

The procedure of Example 1 is followed, but after the addition of sodium meta-aluminate, the mixture is not stirred. The final product contains a mixture of 28 wt% Na (K) P _c and 72 wt% NaA type.

The product can be used in the manufacture of detergent powder.

Claims (3)

PATENT CLAIMS Example 1 300 g of Perfii K-115 Perlite (hereinafter Perfii) are used as starting material. Its chemical composition is as follows: SiO ₂ 76% by weight Al ₂ O ₃ + TiO ₂ 14 Fe ₂ O ₃ 1 CaO 1.8 MgO 1.8 Well ₂ O 1.6 " K ₂ O 2.0 " H ₂ O + other volatile substances 3.8 A process for the preparation of a zeolite blend of Na (K) Pc + NaA starting from an aqueous slurry comprising naturally occurring SiO ₂ and Al ₂ O sources, sodium hydroxide, water soluble sodium salt and / or water soluble potassium salt. the source of naturally occurring SiO ₂ and Al ₂ O _{3 is} perlite and the Na and / or K hydroxide content of the slurry of water and perlite is adjusted to 5-20% by weight, preferably 7-11% by weight, and the slurry is Aged at 10-70 ° C, preferably at 20-40 ° C, for 8-48 hours, the synthesis slurry at 70-150 ° C, preferably 3 -3HU 199,750 Β sen crystallized with constant stirring to 85 130 ° C, and then the slurry containing the resulting Na (K) P _c, zeolite and water glass were added sodium aluminate in an amount such that the synthesis slurry in the dissolved SiO ₂ / Al ₂ The O ₃ molar ratio should be between 1.5 and 2.0, preferably between 1.7 and 2.0, the slurry is aged at 10-70 ° C for 8 to 48 hours, and then the pH of the synthesis slurry is with hydroxide in the range of 13.4 to 14.4 and the synthesis slurry Crystallization is carried out at 60-100 ° C, preferably 75-80 ° C, and the crystalline product is isolated in a known manner. Process according to claim 1, characterized in that the starting material is expanded perlite. 3. A process according to claim 2, wherein the expanded perlite is at least 90% by weight. It consists of particles smaller than 5 pm.