JPH0551533B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to zeolite compositions. Specifically, the present invention relates to a novel crystalline aluminophosphosilicate porous material. [Prior Art] As is well known, zeolites have a wide range of uses, including as catalysts, adsorbents, and ion exchange agents. As a catalyst, it is used in large quantities, for example, for cracking petroleum. This is because zeolite has strong solid acid sites and is also excellent in practical aspects such as heat resistance. Also,
Zeolite catalysts also have good reaction selectivity. Zeolite is generally an aluminosilicate, and its crystals have a strong and uniform pore structure, making it possible to distinguish the size of molecules to a certain extent and having reaction selectivity. Therefore, in reactions where reaction selectivity is important, zeolite catalysts play a large role. Zeolite is a crystal, and when observing its powder X-ray pattern, zeolites with different structures will have different powder X-ray diffraction patterns that reflect their structures. It is said that the number of zeolites that have been identified in this way is approximately 40 types of natural zeolites and more than 100 types of synthetic zeolites. This is because although zeolites are crystals resulting from a combination of relatively simple compounds, the product is not necessarily the thermodynamically most stable phase but a metastable phase. Zeolites are first characterized by their skeletal structure, but other properties are also important. Especially when used as a catalyst, differences in other properties may affect reaction activity even if zeolites have the same skeletal structure. have a big impact. For example, the silica/alumina ratio of zeolite affects the number and strength of solid acid sites,
Crystal size is related to reaction selectivity. Furthermore, the distribution position of catalyst active sites may also affect the reaction activity and product distribution. Synthetic zeolites, particularly crystalline aluminosilicate zeolites, are generally synthesized by heating a mixture consisting of at least an alumina source, a silica source, a hydroxide source and water. Heating is practically carried out at temperatures of about 80° C. to about 300° C. under autogenous water vapor pressure, and this reaction is commonly referred to as a hydrothermal reaction. Zeolite manufacturing method is RMBarrier
Since their pioneering research, numerous studies have been carried out due to its practical importance. In recent years, by adding organic template agents such as organic ammonium ions and organic amines to a mixture consisting of an alumina source, a silica source, a hydroxide source, and water, zeolites with a crystal structure different from conventional ones have been produced. It was reported that.
Examples of such zeolites include ZSM-
So-called pentasil type zeolites such as 5 or ZSM-11 are representative. Pentasil type zeolite exhibits effective shape selectivity because it has pores consisting of 10-membered oxygen rings. This zeolite is an excellent catalyst especially for gasoline synthesis from methanol, selective synthesis of aromatic compounds, etc. In addition to its unique structure, pentasil-type zeolite is also characterized by a high silica/alumina molar ratio compared to natural zeolites or previously known synthetic zeolites, and the silica/alumina molar ratio ranges from approximately 20 to almost infinity. It can be changed up to. The above pentasil type zeolites, especially ZSM−
So-called high-silica zeolites, represented by type 5 zeolites, are often superior in terms of reaction selectivity and catalyst life compared to conventional zeolites, so their synthesis methods have been studied from various angles, and various methods have been proposed. A manufacturing method has been proposed. ZSH-5
A rough summary of some of the research on zeolites is as follows: Synthesis methods using cheaper organic template agents (JP-A No. 53-134799, JP-A No. 55-67522, etc.) Synthesis methods of crystals with more defined forms , a method for producing particularly large crystals (Japanese Patent Application Laid-Open No. 56-45819,
JP-A-56-114817, etc.) Control of aluminum distribution position (USP
4088605) or composite zeolite (Japanese Unexamined Patent Publication No. 58-24353) Zeolite in which part or most of the aluminum in the lattice is replaced with other elements such as boron, iron, gallium, etc. (Japanese Unexamined Patent Application No. 53-55500) can be mentioned. [Problems to be solved by the invention] By the way, since zeolite is usually synthesized from a gel that is chemically rigorous and difficult to define in a uniform manner, in addition to the charging composition ratio, hydrothermal reaction conditions and room temperature The zeolite produced may differ depending on the aging time and raw material source. In other words, the zeolite production process is extremely complex, and although it is possible to some extent to design zeolites inductively based on existing data, it remains unclear what synthesis conditions are required to obtain a new crystal structure. It is difficult to think about this deductively. Therefore, current zeolite synthesis involves many elements of trial and error. This point also applies to ZSM-5 type zeolite, which has many research reports. Furthermore, it is difficult to completely control catalyst activity and selectivity from the zeolite synthesis stage. [Means for Solving the Problems] In view of the above background, the present inventors have conducted intensive studies on a more effective zeolite synthesis method, and as a result, have found that the methods used in conventional zeolite synthesis, particularly pentasil type zeolite synthesis, By using an alumina source, which has rarely been used, and coexisting a phosphoric acid source, we have discovered a new zeolite composition with several characteristics. Furthermore, the present invention was completed with the result that when these were applied as a catalyst, the selectivity was much better than that of the conventional ZSM-5 type zeolite. That is, an object of the present invention is to provide a new and useful zeolite composition, the gist of which is to provide an aqueous mixture containing a poorly water-soluble alumina source, a silica source, a phosphoric acid source, and a tetraalkylammonium bromide. Crystalline aluminophosphosilicate obtained by hydrothermal reaction, Si0 ₂ /
Al ₂ O ₃ molar ratio is 1 to 50, P ₂ O ₅ /Al ₂ O ₃ molar ratio is
0.01 to 10, and the main powder X-ray diffraction peaks are as shown in Table 1 or Table 2 below:

【table】

A zeolite composition characterized by being as shown in [Table]. The present invention will be described in detail below, but first, the characteristics of the zeolite composition and its synthesis method according to the present invention will be described. The first feature is that in the production of the zeolite composition according to the present invention, a solid alumina source that is substantially insoluble in water is used as the alumina source. Conventionally, when synthesizing zeolite with a silica/alumina ratio of 10 or more, it has been common to use an alumina source that is easily soluble in water. Typical examples of such alumina sources are aluminum sulfate,
Examples include sodium aluminate. The reason for this is presumed to be that when a gel is prepared using a water-soluble alumina source, a gel with better reactivity is produced and the growth of zeolite crystals becomes easier. On the other hand, examples of using a water-insoluble alumina source are relatively common in the synthesis of zeolites with a low silica/alumina molar ratio, such as CSZ/type 1 zeolite (Japanese Unexamined Patent Publication No. 57-7823). In the examples of ZSM-5 type zeolite synthesis, there are overwhelmingly many experimental examples using water-soluble alumina sources. Even if the present inventors used a water-soluble alumina source, under conditions where phosphoric acid etc. were present,
It has been found that a zeolite composition is produced that has better properties than the water-soluble alumina sources commonly used in the past. Water-insoluble alumina sources include aluminum hydroxide, hydrated alumina,
Various amorphous or crystalline aluminas, aluminum phosphates, etc. can be mentioned, and any of them can be applied to the present invention, but among these, it is more preferable to use pseudoboehmite phase alumina. The second feature of the present invention is that the silica/alumina molar ratio at the time of charging can be significantly lowered for high-silica zeolite, especially ZSM-5 type zeolite, so that the silica/alumina molar ratio of the product is also the same. This point is that it is very low. Mobile
High silica zeolite developed by Oil Company
ZSM-5 has been synthesized over a wide range of products with a silica/alumina molar ratio of usually 20 or more, to products with almost no alumina present. As mentioned above, ZSM-5 type zeolite is characterized by a high silica/alumina molar ratio, and in actual production and usage examples, the ratio is often about 30 or more. In the synthesis of high-silica zeolite, the silica/alumina molar ratio of the charged gel composition approximately corresponds to the silica/alumina molar ratio of the product, so this ratio at the time of charging is often about 30 or more. If this ratio is low, especially below 20, other crystalline phases, such as mordenite or α-cristobalite, will replace ZSM-5 zeolite as the main crystalline phase, or only an amorphous product will be obtained. I can't. That is, it has been difficult to synthesize ZSM-5 type zeolite that is substantially free from contamination with other impurity phases. Therefore, when these were used as catalysts, the reaction selectivity was naturally not good. However, the present inventors have found that by using a water-insoluble alumina source, especially a pseudoboehmite phase, and coexisting a phosphoric acid source, the desired zeolite phase can be easily formed even when the silica/alumina molar ratio is lower than 20. It has been found that it can be produced while suppressing the contamination of other crystal phases. According to the present invention, even if the silica/alumina molar ratio at the time of charging is lower than 20 and even about 5, ZSM-5 type zeolite can be used as a pure crystal phase or as an almost pure crystal containing only a trace amount of other crystal phases. It has become clear that it can be obtained as a composition. Note that even when some other crystal phases are observed in the powder X-ray pattern, the reaction selectivity is good. A third feature of the present invention is that phosphorus is contained in the zeolite composition according to the present invention. For zeolites, such as ZSM-5 type zeolites, a method is generally known in which the zeolite is synthesized once and then modified with various phosphorus compounds (J. Catal., 76418 ('82)). It has been recognized that the selectivity of the reaction as a catalyst is improved by supporting phosphorus.On the other hand, there are also known techniques for producing zeolite by adding a phosphoric acid source during synthesis; -13621 discloses a method of using phosphate as a buffering agent. In this patent publication, phosphate is This paper describes a method for producing zeolite with a defined crystalline form by adding As you can see, the phosphorus content contained in ZSM-5 type zeolite is small.In contrast, according to the zeolite manufacturing method that the present inventors have completed, the phosphorus content in the product is small. The amount is at least 0.05wt% and in some cases
It reaches over 1.0wt%. That is, a considerable amount of phosphorus is present in the zeolite composition according to the present invention before it is modified. A fourth feature of the present invention is that when the zeolite composition according to the present invention is used as a catalyst, its reaction selectivity is good. That is, for example, the ZSM-5 type zeolite produced according to the present invention has superior reaction selectivity compared to the conventional ZSM-5 type zeolite, as is clear from the examples shown later. It has been found that the shape selectivity retained by the zeolite is further improved. Next, a method for producing a zeolite composition according to the present invention will be explained. The zeolite composition of the present invention is synthesized similarly to conventional aluminosilicate zeolite synthesis by forming a reaction mixture and then heating it until crystallization proceeds. The reaction mixture contains a phosphoric acid source, an alumina source, a silica source, a hydroxide source (if necessary),
Prepared by mixing water and tetraalkylamonium bromide. Phosphoric acid is preferably used as the phosphoric acid source, and alumina substantially insoluble in water, especially pseudoboehmite phase, is preferably used as the alumina source. It is also possible to use an alumina source or aluminum phosphate that is capable of forming insoluble alumina in an aqueous solution and a combination of a phosphoric acid source and an aluminum source that are capable of forming it in an aqueous solution. As the silica source, water glass, colloidal silica, silica hydrogel, silicic anhydride, orthoethylsilicate, etc. used in conventional zeolite production techniques can be used, but the preferred silica source is colloidal silica. Moreover, as the tetraalkylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, etc. are used. The addition of hydroxide sources can also be omitted when water glass is used as a silica source, but when using silica sol, for example, alkali hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth It is necessary to add an appropriate amount of hydroxide or the like. The composition range of the slurry mixture prepared before the hydrothermal reaction is appropriately selected from the following ranges. This range does not necessarily match the composition of the produced zeolite, and there are conditions in which the raw material is dissolved in the water solvent and is not incorporated into the product. Therefore, the silica source may be charged in excess.

〔Example〕

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the following Examples unless it exceeds the gist thereof. In the following examples, a product manufactured by Condeia Co., Ltd. (AlO ₃ content: 75%) was used as the pseudo-boehmite, and a product manufactured by Catalyst Kasei Co., Ltd. (Cataroid S-30H, SiO ₂ content: 30%) was used as the silica sol. Example 1 15.2g of sodium hydroxide was dissolved in 200ml of water,
This was mixed with an aqueous solution of 23.1 g of 85% phosphoric acid dissolved in 200 ml of water. Add 18.7 g of tetrapropylammonium bromide (TPABr) to this solution,
6.9 g of pseudo-boehmite was added while stirring.
After stirring this mixture until homogeneous, 100.2
g of silica sol were gradually added, followed by a solution of 4.5 g of sodium hydroxide dissolved in 30 ml of water, and the mixture was stirred at room temperature for about 30 minutes. This gel composition was transferred to a stainless steel autoclave and heated at 160 °C for 75 min.
A hydrothermal reaction was carried out by heating for a period of time. The product was collected by filtration, washed with 1 part of water, 500 ml of hot water, and 200 ml of water, and then dried at 100°C. Yield: 47.5g.
The powder X-ray diffraction diagram of this product showed a ZSM-5 type pattern (Table 1 above), and a very small amount of diffraction peaks believed to be due to gismonden type crystals were detected. The gel composition in this example was SiO ₂ /Al ₂ O ₃ 10,
P ₂ O ₅ /SiO ₂ 0.20, NaOH/SiO ₂ 0.96, R/
SiO ₂ was 0.14. Also, the chemical analysis value of the product is
P1.6wt% _{, P2O5} / _SiO2 molar _ratio 0.21, _SiO2 / _Al2O3
The molar ratio was 10.1. Examples 2 to 10 Synthesis was carried out in substantially the same manner as in Example 1. Table 3 shows these gel compositions and hydrothermal reaction conditions. Comparative Example 1 A mixture having the same composition as in Example 8 was prepared using sodium aluminate instead of pseudoboehmite as an alumina source, and a hydrothermal reaction was performed at 150° C. for 68 hours. The powder X-ray diffraction pattern of the product was determined to be an amorphous phase. Example 11 The hydrothermal reaction products synthesized in Examples 1 to 10 were catalyzed (converted into H-type) as follows. First, the hydrothermal reaction product was calcined at 540°C for 6 hours under air circulation. Next, 1.33g of ammonium chloride per 1.0g of this fired product,
The mixture was heated at 100° C. for 2 hours in an aqueous solution containing 11.1 ml of water, and then filtered. After repeating this operation three times, the product was thoroughly washed with water and dried at 100°C. The mixture was further compressed into tablets to have a particle size of 7 to 12 meshes, and then fired again at 540° C. for 6 hours under air circulation. Table 3 lists these catalyst numbers and chemical analysis results.

[Table] Examples 12 to 16 Using each catalyst prepared in Example 11, an alkylation reaction of toluene with methanol was carried out, and p-
Shape selectivity for xylene synthesis was evaluated. The reaction was a normal pressure flow reaction using a quartz reaction tube. The reaction conditions were a toluene/methanol molar ratio of 2.
This was done with WHSV10hr ^-1 . The catalyst was pretreated at 500° C. for 1 hour in a nitrogen stream before being subjected to the reaction. These results are summarized in Table 4. Comparative Example 2 ZSM-5 type zeolite was synthesized as follows using a water-soluble alumina source without adding a phosphoric acid source. 6.2 g of sodium aluminate was added to an aqueous solution of 2.9 g of sodium hydroxide dissolved in 100 ml of water, followed by 29.9 g of diethanolamine.
Next, 264 g of silica gel was added while stirring, and the mixture was further stirred at room temperature for 30 minutes. This aqueous gel solution was subjected to a hydrothermal reaction at 170°C for 86 hours. Comparative Example 3 The hydrothermal reaction product of Comparative Example 2 was catalyzed in the same manner as in Example 11, and the reaction was carried out under the same conditions as in Example 12. The results are shown in Table 4.

【table】

〔Effect of the invention〕

The zeolite composition of the present invention has good selectivity, particularly shape selectivity, when used as a catalyst.

Claims (1)

[Scope of Claims] 1 A crystalline aluminophosphosilicate obtained by hydrothermally reacting an aqueous mixture containing a poorly water-soluble alumina source, a silica source/phosphoric acid source, and a tetraalkylammonium bromide, comprising: Si0 ₂ /Al ₂ O ₃ molar ratio is 1 to 50, P ₂ O ₅ /Al ₂ O ₃
A zeolite composition having a molar ratio of 0.01 to 10 and a main powder X-ray diffraction peak as shown in Table 1 or Table 2 below. [Table] [Table] [Table] [Table] 2. The zeolite composition according to claim 1, wherein the alumina source is pseudoboehmite.