CN1397493A - Diphase symbiotic molecular sieve and its synthesizing process - Google Patents

Abstract

A class of twelve-membered ring structure two-phase intergrowth molecular sieves, including three kinds of two-phase intergrowth molecular sieves of beta zeolite-mordenite, beta zeolite-ZSM-12 and mordenite-ZSM-12. It is characterized in that the mass fraction of any one of the two symbiotic phases can be adjusted arbitrarily between 0 and 1, so that it has the advantages of the two symbiotic phases. The expression of its anhydrous chemical composition (calculated by oxide molar ratio) is: xNa ₂ O·Al ₂ O ₃ ·ySiO ₂ , where x=0.005-2.0, y=5-300. The characteristic of the synthesis method is that various solid SiO ₂ are used as silicon source, tetraethylammonium salt is used as template agent or tetraethylammonium salt-fluoride is used as composite template agent for hydrothermal synthesis. The molar composition of the reaction system is: SiO ₂ /Al ₂ O ₃ =5-1500, (TEA) ₂ O/SiO ₂ =0.01-0.30, Na ₂ O/SiO ₂ =0.10-0.60, H ₂ O/SiO ₂ = 2 to 50, F ⁻ /SiO ₂ =0 to 0.30. The synthesis conditions can be changed according to the needs to regulate the two-phase composition and the silicon-aluminum ratio in the two-phase symbiotic molecular sieve.

Description

A class of twelve-membered ring structure two-phase intergrowth molecular sieve and its synthesis method

The invention relates to a class of twelve-member ring structure two-phase symbiotic molecular sieves and a synthesis method thereof. The technical field belongs to C01B 39/00 according to the international patent classification. The two-phase symbiotic molecular sieve with twelve-membered ring structure refers to zeolite-mordenite two-phase symbiotic molecular sieve, zeolite beta-ZSM-12 two-phase symbiotic molecular sieve and mordenite-ZSM-12 two-phase symbiotic molecular sieve.

In crystallography, a material that grows an ordered structure of another crystal in an ordered structure and exhibits two-phase characteristics is called intergrowth of two phases. The formula ...ABBABABABABABABABCABC...ABCABCABABAB... can represent the intergrowth of the packing unit ABC in the crystal with the packing order AB. In crystallography, only two or more compounds with similar structures can form two-phase symbiosis.

Beta zeolite, mordenite and ZSM-12 all have a twelve-membered ring channel structure, and their basic structural units are similar, so they can form two-phase symbiotic molecular sieves. Beta zeolite, mordenite and ZSM-12 are all excellent catalytic materials. Although beta zeolite has three-dimensional intersecting channels, the synthesis cost is relatively high. Mordenite and ZSM-12 only have one-dimensional channels, and mordenite is easy to be catalytically deactivated. However, the synthesis cost is low, so the synthesis of two-phase co-growth molecular sieves with the advantages of the two molecular sieves is of great practical significance for the development of low-cost catalytic materials with good catalytic activity and long-life catalytic stability.

The structure of the two-phase intergrowth molecular sieve is different from the mechanical mixture of two molecular sieves, so it has better catalytic performance. There are few documents about the synthesis of two-phase symbiotic molecular sieves. "Zeolites", 1986, 6: 396-402 reported the synthesis of ZSM-5/ZSM-11 two-phase symbiotic molecular sieves, "Chem Mater", 1994, 6(12): From 2201 to 2204, the synthesis of FAU/EMT two-phase symbiotic molecular sieves was reported. However, there are no reports on the catalytic effect of two-phase symbiotic molecular sieves.

The object of the present invention is to provide a class of twelve-membered ring structure two-phase intergrowth molecular sieves, including beta zeolite-mordenite two-phase intergrowth molecular sieves, beta zeolite-ZSM-12 two-phase intergrowth molecular sieves and mordenite-ZSM-12 two-phase intergrowth molecular sieves . In the intergrown two phases of this twelve-membered ring structure two-phase intergrown molecular sieve, the mass fraction of any one phase can be adjusted arbitrarily between 0 and 1, so that it has the advantages of the intergrown two phases.

The object of the present invention is also to provide a kind of synthetic technology of twelve-membered ring structure two-phase intergrowth molecular sieve, the characteristic is to make silicon source with cheap industrial silica sol, industrial water glass and various solid SiO _etc. , use tetraethylammonium Under the conditions of halide, tetraethylammonium hydroxide or their mixture template or compound template composed of tetraethylammonium halide, tetraethylammonium hydroxide and fluoride, hydrothermal synthesis of zeolite beta-mordenite Two-phase symbiotic molecular sieves, beta zeolite-ZSM-12 two-phase symbiotic molecular sieves and mordenite-ZSM-12 two-phase symbiotic molecular sieves.

According to the synthesized 12-membered ring structure two-phase symbiotic molecular sieve of the present invention, the mass fraction of any phase in the symbiotic two phases can be adjusted arbitrarily between 0 and 1, and its anhydrous chemical composition (in terms of oxide molar ratio) can be expressed as The formula is: xNa ₂ O·Al ₂ O ₃ ·ySiO ₂ , where x=0.005-2.0, y=5-300.

According to the method for synthesizing a two-phase symbiotic molecular sieve with a twelve-membered ring structure provided by the present invention, the specific embodiment is to add silicon source, aluminum source, and inorganic base to an alkaline solution containing a template or a composite template, and stir evenly Hydrothermal crystallization at 100-250° C. for 20-120 hours. After the crystallization is completed, the crystallization obtained is filtered, washed and dried to obtain the zeolite product.

In the method of the present invention, the molar composition of the reaction system is: SiO ₂ /Al ₂ O ₃ =5-1500, (TEA) ₂ O/SiO ₂ =0.01-0.30, Na ₂ O/SiO ₂ =0.10-0.60, H ₂ O/SiO ₂ =2 to 50, F ⁻ /SiO ₂ =0 to 0.30.

According to the method provided by the present invention, the template is tetraethylammonium halide, tetraethylammonium hydroxide or a mixture thereof. The composite template is composed of tetraethylammonium halide, tetraethylammonium hydroxide or their mixture and fluoride. The fluoride constituting the composite template agent is alkali metal fluoride or ammonium fluoride or a mixture thereof.

According to the method provided by the present invention, the silicon source is any one or more of silica sol, solid silica gel, water glass, white carbon black, and amorphous silica. The aluminum source is one or more of aluminum trichloride, aluminum sulfate, aluminum nitrate, sodium aluminate, aluminum hydroxide and pseudo-boehmite. Described inorganic base is ammonium hydroxide, sodium hydroxide, and sodium hydroxide can be replaced by the hydroxide of other alkali metal or alkaline earth metal.

The XRD characteristics of the β zeolite-mordenite two-phase intergrowth molecular sieve synthesized by the present invention are listed in Table 1.

Table 1 2θ/° d(nm) I/I ₀ 6.49 1.361 S 7.64 1.155 W-VW 8.65 1.022 VW 9.74 0.908 S-VS 13.18 0.671 VW 13.47 0.657 W M 13.84 0.639 VW 14.65 0.604 VW 15.28 0.579 VW 19.65 0.483 W M 21.48 0.413 VW-W 22.32 0.398 S-VS 23.18 0.383 VW 23.69 0.375 VW 25.27 0.352 VW 25.68 0.347 S-VS 26.34 0.338 W M 26.90 0.331 VW 27.16 0.328 VW 27.67 0.322 W 27.88 0.320 W 30.96 0.288 VW-W 35.15 0.255 VW 35.75 0.251 VW 43.45 0.208 VW

Strength in the table: VS80～100%; S60～80%; M40～60%; W20～40%; VW＜20%

The XRD characteristics of the zeolite beta-ZSM-12 two-phase intergrowth molecular sieve synthesized by the present invention are listed in Table 2.

Table 2 2θ/° d(nm) I/I ₀ 7.34 1.204 S-VS 7.83 1.130 W M 8.73 1.013 W 14.86 0.596 VW 18.72 0.474 VW 20.70 0.429 S-VS 21.48 0.414 W 22.45 0.396 VW 22.94 0.388 MS 24.45 0.364 VW 25.51 0.349 W-VW 26.41 0.337 W 26.76 0.333 VW 27.89 0.320 VW 28.69 0.311 VW 29.53 0.302 VW 30.85 0.290 VW 33.43 0.268 VW 35.30 0.254 VW

Strength in the table: VS80～100%; S60～80%; M40～60%; W20～40%; VW＜20%

The XRD characteristics of the mordenite-ZSM-12 two-phase intergrowth molecular sieve synthesized in the present invention are listed in Table 3.

table 3 2θ/° d(nm) I/I ₀ 6.49 1.361 S 7.47 1.184 S 7.63 1.159 vs. 8.91 0.993 MS 9.74 0.908 S-VS 13.45 0.658 W M 13.83 0.640 VW-W 14.59 0.607 VW 15.28 0.579 VW 19.65 0.483 W 20.99 0.423 S 22.20 0.400 W 23.03 0.386 VW 23.18 0.383 VW 23.36 0.380 VW-W 25.68 0.347 S 26.36 0.338 W M 27.67 0.322 W 27.88 0.320 W 30.89 0.289 VW 35.61 0.252 VW

Strength in the table: VS80～100%; S60～80%; M40～60%; W20～40%; VW＜20%

According to the technology provided by the present invention, the composition of the two phases in the two-phase symbiotic molecular sieve can be regulated by changing the synthesis conditions, and the silicon-aluminum ratio of the two-phase symbiotic molecular sieve can also be regulated by changing the synthesis conditions.

The beta zeolite-mordenite two-phase symbiotic molecular sieve provided by the invention can be transformed into a hydrogen form by acid washing after being roasted to remove the template agent, or can be converted into a hydrogen form by being roasted after being exchanged with an ammonium salt solution. Various metals or their compounds, such as alkali metals, alkaline earth metals, rare earth elements, Pt, Pd, Re, Sn, Ni, W, Co, and other elements or their compounds, can be introduced into it by ion exchange, impregnation or other methods to make it It becomes a zeolite modified by different metals; it can also introduce compounds of different compounds such as P, Ga, Ti, B and other elements to make it a zeolite with special purposes. The β zeolite-mordenite two-phase symbiotic molecular sieve and its improved type provided by the present invention can be used as an adsorbent and a catalytic conversion process of various organic compounds, especially in the transalkylation, alkylation, isomerization, Disproportionation and catalytic cracking, hydrocracking, olefin hydration and other processes, as well as various fine chemical synthesis processes such as nitration and ammonification.

The following examples will further illustrate the present invention. However, these examples do not limit the scope of the present invention. The elemental analysis of zeolite in the embodiment adopts ICP method.

Example 1

According to the method provided by the invention, the beta zeolite-mordenite two-phase intergrowth molecular sieve is synthesized. After dissolving 17.8 g of tetraethylammonium bromide (98 wt%, chemically pure) in 45 g of water, add 82 g of ammonia water (analytical pure, containing 25 wt% NH ₃ , commercially available). 3.5 g of sodium fluoride (analytical grade, commercially available) and 3.4 g of sodium hydroxide (analytical grade, commercially available) were added under stirring, and 7.05 g of sodium aluminate (analytical grade, commercially available) was added after dissolution. Continue to add 190 g of silica sol (industrial product, content 25 wt%), stir evenly, transfer to a stainless steel reaction kettle, and crystallize at 160° C. for 3 days. Suction filtration, washing and drying are carried out after crystallization to obtain a two-phase symbiotic molecular sieve product of beta zeolite-mordenite. In the obtained product, mordenite accounts _for 80 wt%, and beta zeolite accounts for _{20 wt %} . The molar ratio of raw materials is: 1Al ₂ O ₃ ·28SiO ₂ ·1.4(TEA) ₂ O · 4.3Na ₂ O · 2.8F ^- ·378H ₂ O

Example 2

According to the method provided by the invention, the beta zeolite-mordenite two-phase intergrowth molecular sieve is synthesized. Get 83.8 grams of tetraethylammonium hydroxide (content 14.6wt%, industrial product), add 3.4 grams of sodium hydroxide (analytically pure, commercially available) under stirring, add 7.05 grams of sodium aluminate (analytical pure, commercially available) after dissolving again commercially available). Continue to add 190 g of silica sol (industrial product, content 25 wt%), stir evenly, transfer to a stainless steel reaction kettle, and crystallize at 160° C. for 3 days. Suction filtration, washing and drying are carried out after crystallization to obtain a two-phase symbiotic molecular sieve product of beta zeolite-mordenite. In the obtained product, _mordenite accounts for 75wt%, and _beta zeolite accounts for _{25wt %} . The molar ratio of raw materials is: 1Al ₂ O ₃ 28SiO ₂ 1.4(TEA) ₂ O 2.9Na ₂ O 378H ₂ O

Example 3

According to the method provided by the invention, the beta zeolite-mordenite two-phase intergrowth molecular sieve is synthesized. Get 83.8 grams of tetraethylammonium hydroxide (content 14.6wt%, industrial product), add 3.4 grams of sodium hydroxide (analytically pure, commercially available) under stirring, add 7.05 grams of sodium aluminate (analytical pure, commercially available) after dissolving commercially available). Continue to add 190 g of silica sol (industrial product, content 25 wt%), stir evenly, transfer to a stainless steel reaction kettle, and crystallize at 140° C. for 3 days. Suction filtration, washing and drying are carried out after crystallization to obtain a two-phase symbiotic molecular sieve product of beta zeolite-mordenite. In the obtained product, mordenite accounts for 40 _wt %, and _beta zeolite accounts for 60 _{wt %} . The molar ratio of raw materials is: 1Al ₂ O ₃ 28SiO ₂ 1.4(TEA) ₂ O 1.4Na ₂ O 378H ₂ O

Example 4

According to the method provided by the invention, the beta zeolite-mordenite two-phase intergrowth molecular sieve is synthesized. Get 83.8 grams of tetraethylammonium hydroxide (content 14.6wt%, industrial product), add 3.4 grams of sodium hydroxide (analytically pure, commercially available) under stirring, add 4.69 grams of sodium aluminate (analytically pure, commercially available) after dissolving commercially available). Continue to add 190 g of silica sol (industrial product, content 25 wt%), stir evenly, transfer to a stainless steel reaction kettle, and crystallize at 140° C. for 3 days. Suction filtration, washing and drying are carried out after crystallization to obtain a two-phase symbiotic molecular sieve product of beta zeolite-mordenite. In the obtained product, mordenite accounts _for 30 wt%, and beta zeolite accounts for _{70 wt} % _. The molar ratio of raw materials is: 1Al ₂ O ₃ 40SiO ₂ 1.4(TEA) ₂ O 1.4Na ₂ O 378H ₂ O

Example 5

According to the method provided by the invention, the beta zeolite-mordenite two-phase intergrowth molecular sieve is synthesized. Get 83.8 grams of tetraethylammonium hydroxide (content 14.6wt%, industrial product), add 3.4 grams of sodium hydroxide (analytically pure, commercially available) under stirring, add 7.05 grams of sodium aluminate (analytical pure, commercially available) after dissolving again commercially available). Continue to add 50 grams of solid sol (industrial product), stir evenly, transfer to a stainless steel reaction kettle, and crystallize at 160° C. for 1 day. Suction filtration, washing and drying are carried out after crystallization to obtain a two-phase symbiotic molecular sieve product of beta zeolite-mordenite. In the obtained product, mordenite accounts _for 80 wt%, and beta zeolite accounts for _{20 wt} % _. The molar ratio of raw materials is: 1Al ₂ O ₃ 28SiO ₂ 1.4(TEA) ₂ O 1.4Na ₂ O 378H ₂ O

Example 6

According to the method provided by the invention, the beta zeolite-mordenite two-phase intergrowth molecular sieve is synthesized. Get 83.8 grams of tetraethylammonium hydroxide (content 14.6wt%, industrial product), add 3.4 grams of sodium hydroxide (analytically pure, commercially available) under stirring, add 7.05 grams of sodium aluminate (analytical pure, commercially available) after dissolving again commercially available). Continue to add 50 grams of white carbon black (industrial product), stir evenly, transfer to a stainless steel reaction kettle, and crystallize at 160° C. for 1.5 days. Suction filtration, washing and drying are carried out after crystallization to obtain a two-phase symbiotic molecular sieve product of beta zeolite-mordenite. In the obtained product, _mordenite accounts for 75wt%, and _beta zeolite accounts for _{25wt %} . The molar ratio of raw materials is: 1Al ₂ O ₃ 28SiO ₂ 1.4(TEA) ₂ O 1.4Na ₂ O 378H ₂ O

Example 7

According to the method provided by the invention, the beta zeolite-mordenite two-phase intergrowth molecular sieve is synthesized. Take 83.8 grams of tetraethylammonium hydroxide (content 14.6wt%, industrial product), and add 20 grams of aluminum sulfate (analytical pure, commercial product) under stirring. Continue to add 180 grams of water glass (industrial product, content 26wt%), stir evenly, transfer to a stainless steel reactor, and crystallize at 160° C. for 1.5 days. Suction filtration, washing and drying are carried out after crystallization to obtain a two-phase symbiotic molecular sieve product of beta zeolite-mordenite. In the obtained product, mordenite accounts _for 85wt%, and beta zeolite accounts for _{15wt % .} The molar ratio of raw materials is: 1Al ₂ O ₃ ·28SiO ₂ ·1.4(TEA) ₂ O · 8.5Na ₂ O · 378H ₂ O

Example 8

According to the method provided by the invention, the beta zeolite-mordenite two-phase intergrowth molecular sieve is synthesized. Get 83.8 grams of tetraethylammonium hydroxide (content 14.6wt%, industrial product), add 3.4 grams of sodium hydroxide (analytically pure, commercially available) under stirring, add 7.05 grams of sodium aluminate (analytical pure, commercially available) after dissolving again commercially available). Continue to add 50 grams of amorphous silicon dioxide (industrial product), stir evenly, transfer to a stainless steel reaction kettle, and crystallize at 160° C. for 1.5 days. Suction filtration, washing and drying are carried out after crystallization to obtain a two-phase symbiotic molecular sieve product of beta zeolite-mordenite. In the obtained product, _mordenite accounts for 75wt%, and _beta zeolite accounts for _{25wt %} . The molar ratio of raw materials is: 1Al ₂ O ₃ 28SiO ₂ 1.4(TEA) ₂ O 1.4Na ₂ O 378H ₂ O

Example 9

According to the method provided by the invention, the beta zeolite-mordenite two-phase intergrowth molecular sieve is synthesized. After dissolving 17.8 g of tetraethylammonium bromide (98 wt%, chemically pure) in 45 g of water, add 82 g of ammonia water (analytical pure, containing 25 wt% NH ₃ , commercially available). 5.25 g of sodium fluoride (analytical pure, commercially available) and 3.4 g of sodium hydroxide (analytical pure, commercially available) were added under stirring, and 4.69 g of sodium aluminate (analytical pure, commercially available) was added after dissolution. Continue to add 190 g of silica sol (industrial product, content 25 wt%), stir evenly, transfer to a stainless steel reaction kettle, and crystallize at 140° C. for 3 days. Suction filtration, washing and drying are carried out after crystallization to obtain a two-phase symbiotic molecular sieve product of beta zeolite-mordenite. In the obtained product, mordenite accounts for 20 _wt %, and _beta zeolite accounts for 80 _wt % _. The molar ratio of raw materials is: 1Al ₂ O ₃ 40SiO ₂ 1.4(TEA) ₂ O 3.5Na ₂ O 4.2F ^- 378H ₂ O

Example 10

According to the method provided by the invention, the beta zeolite-mordenite two-phase intergrowth molecular sieve is synthesized. Get 125.7 grams of tetraethylammonium hydroxide (content 14.6wt%, industrial product). 5.25 g of sodium fluoride (analytical pure, commercially available) and 3.4 g of sodium hydroxide (analytical pure, commercially available) were added under stirring, and 0.475 g of sodium aluminate (analytical pure, commercially available) was added after dissolution. Continue to add 190 g of silica sol (industrial product, content 25 wt%), stir evenly, transfer to a stainless steel reaction kettle, and crystallize at 140° C. for 3 days. Suction filtration, washing and drying are carried out after crystallization to obtain a two-phase symbiotic molecular sieve product of beta zeolite-mordenite. In the _obtained product, mordenite accounts for 25wt%, and beta zeolite accounts for _{75wt % .} The molar ratio of raw materials is: 1Al ₂ O ₃ ·400SiO ₂ ·31.1(TEA) ₂ O·3.5Na ₂ O·4.2F ^- ·378H ₂ O

Example 11

According to the method provided by the invention, the beta zeolite-ZSM-12 two-phase symbiotic molecular sieve is synthesized. Take 147 g of tetraethylammonium hydroxide (content 10 wt%, industrial product), and add 0.0944 g of sodium aluminate (analytical pure, commercial product) under stirring. Add 30 grams of solid sol (industrial product), stir evenly, transfer to a stainless steel reaction kettle, and crystallize at 140° C. for 3 days. Suction filtration, washing and drying are carried out after the crystallization is completed to obtain a beta zeolite-ZSM-12 two-phase symbiotic molecular sieve product. In the obtained product, beta _zeolite accounts for 25wt%, and ZSM- ₁₂ accounts for _{75wt %} . The molar ratio of raw materials is: 1Al ₂ O ₃ ·1000SiO ₂ ·100(TEA) ₂ O·1.3Na ₂ O·14700H ₂ O

Example 12

According to the method provided by the invention, the beta zeolite-ZSM-12 two-phase symbiotic molecular sieve is synthesized. 1.714 g of sodium fluoride (analytical pure, commercially available) was added to 169.5 g of tetraethylammonium hydroxide (content 10 wt%, commercial product), and 0.252 g of sodium aluminate (analytical pure, commercially available) was added under stirring. Add 24 grams of solid sol (industrial product), stir evenly, transfer to a stainless steel reaction kettle, and crystallize at 140° C. for 3 days. Suction filtration, washing and drying are carried out after the crystallization is completed to obtain a beta zeolite-ZSM-12 two-phase symbiotic molecular sieve product. In the obtained product, _beta zeolite accounts for 80wt _% , and ZSM- ₁₂ accounts for _20wt %. The molar ratio of the raw material is: 1Al ₂ O ₃ ·300SiO ₂ ·43(TEA) ₂ O · 16Na ₂ O · 30F ^- ·6350H ₂ O

Example 13

The mordenite-ZSM-12 two-phase intergrowth molecular sieve is synthesized according to the method provided by the invention. 0.474 g of sodium aluminate (analytical pure, commercially available) was added to 14.7 g of tetraethylammonium hydroxide (content 10 wt%, commercial product). Add 24 grams of silica sol (content 25wt%, industrial product), stir evenly, transfer to a stainless steel reaction kettle, and crystallize at 150° C. for 2 days. Suction filtration, washing and drying are carried out after crystallization to obtain a mordenite-ZSM-12 two-phase symbiotic molecular sieve product. In the obtained product, mordenite accounts for 80 wt%, ZSM-12 accounts for 20 wt%, and the anhydrous chemical composition of the product (calculated by oxide molar ratio) is expressed as: 0.20Na ₂ O·Al ₂ O ₃ ·21SiO ₂ . The molar ratio of raw materials is: 1Al ₂ O ₃ 50SiO ₂ 2.5(TEA) ₂ O 1.5Na ₂ O 870H ₂ O

Example 14

The beta zeolite-ZSM-12 two-phase intergrowth molecular sieve sample obtained in Example 10 was converted into a hydrogen form by exchange and roasting with ammonium nitrate. After pressing and crushing, take 5ml of the sample passing through 20-40 meshes and put it into the reaction tube of the microreactor. According to the reaction conditions: 220°C, 3.4MPa, toluene/propylene/propane feed molar ratio 4/1/2 Carry out the alkylation reaction of toluene and propylene with toluene feed space velocity LHSV=2h ^-1 , the result after reaction is stable: toluene conversion rate 11.0%, propylene conversion rate 99.9%, isopropyl toluene (IPT) selectivity 87.7% %, ortho (o-), meta (m-), right (p-) isomer distribution of cumene:

o-IPT5.50%, m-IPT65.20%, p-IPT29.30%

Example 15

The beta zeolite-mordenite two-phase symbiotic molecular sieve sample obtained in Example 8 was converted into a hydrogen form by exchange roasting with ammonium nitrate, mixed with pseudo-boehmite at a weight ratio of 1:1, shaped, and roasted at 550°C to produce HMOR-β/ Al ₂ O ₃ catalyst, the results of catalyzed mixed xylene isomerization reaction are shown in Table 4, the reaction conditions are: reaction temperature 280°C, reaction pressure 1MPa, raw material mixed xylene feed space velocity LHSV=2h ^-1 , H ₂ and The volume ratio of xylene is 400-1000, and the micro-reverse loading catalyst is 16ml.

     Table 4 Composition of mixed xylenes before and after isomerization, %

                                     

                                                                                   

    m-xylene                                                      

                                                                 

Example 16

The beta zeolite-mordenite two-phase intergrowth molecular sieve sample obtained in Example 7 was converted into a hydrogen form by exchanging and roasting with ammonium nitrate. After pressing into tablets and crushing, take 5ml of the sample passing through 20 to 40 meshes and put it into the reaction tube of the microreactor. According to the reaction conditions: 160 ° C, methanol feed space velocity LHSV = 2h ^-1 , carry out methanol dehydration to produce dimethyl ether Reaction, the result after the reaction is stable is: methanol conversion rate 92%, dimethyl ether selectivity 100%.

Claims (10)

1. A class of twelve-membered ring structure two-phase symbiotic molecular sieve, characterized in that the mass fraction of any one of the two symbiotic phases can be adjusted arbitrarily between 0 and 1, and its anhydrous chemical composition (calculated by oxide molar ratio) The expression is: xNa ₂ O·Al ₂ O ₃ ·ySiO ₂ , where x=0.005-2.0, y=5-300. 2. According to claim 1, said twelve-membered ring structure two-phase intergrowth molecular sieve is beta zeolite-mordenite two-phase intergrowth molecular sieve, beta zeolite-ZSM-12 two-phase intergrowth molecular sieve and mordenite-ZSM-12 two-phase intergrowth molecular sieve Molecular sieve. 3. a method for synthesizing the described twelve-member ring structure two-phase symbiotic molecular sieve of claim 1, it is characterized in that silicon source, aluminum source, inorganic base are added in containing template agent or in the alkaline solution containing composite template agent, Hydrothermal crystallization at 100-250°C for 20-120 hours, after the crystallization is completed, filter, wash and dry to obtain zeolite-mordenite two-phase symbiotic molecular sieve or zeolite-beta-ZSM-12 two-phase symbiotic molecular sieve or mordenite-ZSM -12 two-phase symbiotic molecular sieve. 4. The method according to claim 3, characterized in that the reaction system has the following molar ratios: SiO ₂ /Al ₂ O ₃ =5-1500, (TEA) ₂ O/SiO ₂ =0.01-0.30, Na ₂ O /SiO ₂ =0.10 to 0.60, H ₂ O/SiO ₂ =2 to 50, F ⁻ /SiO ₂ =0 to 0.30. 5. according to the described method of claim 3, it is characterized in that described templating agent is the halide of tetraethylammonium, tetraethylammonium hydroxide or its mixture. 6. according to the described method of claim 3, it is characterized in that described compound templating agent is made of the halide of tetraethylammonium, tetraethylammonium hydroxide or their mixture and fluoride. 7. The method according to claim 3, characterized in that the silicon source is any one or more of silica sol, solid silica gel, water glass, white carbon black, and amorphous silica. 8. according to the described method of claim 3, it is characterized in that described aluminum source is one or more in aluminum trichloride, aluminum sulfate, aluminum nitrate, sodium aluminate, aluminum hydroxide, pseudo-boehmite kind. 9. The method according to claim 3, characterized in that said inorganic base is ammonium hydroxide, alkali metal or alkaline earth metal hydroxide. 10. The method according to claim 6, characterized in that said fluoride is alkali metal fluoride or ammonium fluoride or a mixture thereof.