WO2022104580A1 - Mordenite molecular sieve, and preparation method and use therefor - Google Patents

Abstract

Provided is a mordenite molecular sieve, and a preparation method and use therefor. The mordenite molecular sieve is selected from any one of the following anhydrous chemical formulas; RaQbMC(SixAly)O2, wherein R is a first templating agent, and R is any one of tetramethyl diamine compounds; Q is a second templating agent, and Q is any one of cyclohexylamine compounds; M is an alkali metal ion; a represents the number of moles of R corresponding to each mole of (SixAly)O2; b represents the number of moles of Q corresponding to each mole of (SixAly)O2; c represents the number of moles of M corresponding to each mole of (SixAly)O2; x and y respectively represent the number of moles of Si and Al. The present mordenite molecular sieve is prepared from two templating agents. A high-silicon-aluminum ratio can be obtained, and the proportion of acid centers of an 8-membered ring channel of the mordenite molecular sieve to the total B acid centers can be flexibly adjusted within a certain range.

Description

Mordenite molecular sieve and preparation method and application technical field

The application relates to a mordenite molecular sieve, a preparation method and an application, and belongs to the technical field of molecular sieves.

Background technique

和8元环

孔道组成，二者由沿b轴方向的8元环

短孔道相互连通，两个交叉的8元环孔道构成“侧口袋”。由于沿c轴的8元环孔道较窄，大多数分子无法穿过，因此MOR在催化反应中多表现为一维孔道分子筛的性质。丝光沸石已被证明是二甲醚DME羰基化反应的有效分子筛催化剂。特别是丝光沸石显示出高的羰基化活性和MA选择性。先前的工作已经证明，DME在酸性沸石上的羰基化机理涉及DME在B酸位上的吸附形成甲氧基，并随后与CO反应生成乙酰基中间体，进而与DME反应生成MA。其中，乙酰基的生成是整个反应的决速步骤。此外，研究发现羰基化的活性中心位于8元环侧口袋内，而12元环主孔道的酸性位会引起副反应，导致催化剂积碳失活。因此制备8元环孔道B酸比例高的丝光沸石有利于提高催化剂二甲醚羰基化反应性能。而现有合成技术一般难以实现对铝分布的调控。另外低硅铝比的丝光沸石在实际应用存在一些明显的不足，比如水热稳定性差，容易积碳失活等。因此，制备高硅的8元环孔道酸量高的丝光沸石具有重要意义。 Porous materials are widely used in many fields such as adsorption, separation, ion exchange and catalysis due to their specific pore structure and uniform pore size. Mordenite (abbreviated as MOR) is one of the earliest known zeolites, and it is divided into two types: natural and synthetic. In 1864, How named the natural mordenite for the first time. The framework of mordenite consists of 12-membered rings along the c-axis

and 8-membered ring

The channels are composed of 8-membered rings along the b-axis.

The short pore channels are interconnected, and the two intersecting 8-membered ring pore channels constitute "side pockets". Due to the narrow 8-membered ring pore along the c-axis, most molecules cannot pass through, so MOR mostly behaves as a one-dimensional pore molecular sieve in the catalytic reaction. Mordenite has been shown to be an efficient molecular sieve catalyst for the carbonylation of dimethyl ether (DME). Mordenite, in particular, shows high carbonylation activity and MA selectivity. Previous work has demonstrated that the carbonylation mechanism of DME on acidic zeolites involves the adsorption of DME at the B acid site to form a methoxy group, which subsequently reacts with CO to form an acetyl intermediate, which in turn reacts with DME to form MA. Among them, the formation of acetyl group is the rate-determining step of the whole reaction. In addition, it was found that the active center of carbonylation was located in the side pocket of the 8-membered ring, and the acidic site of the main pore of the 12-membered ring would cause side reactions and lead to the deactivation of catalyst carbon deposition. Therefore, the preparation of mordenite with a high proportion of 8-membered ring pore B acid is beneficial to improve the performance of the catalyst for the dimethyl ether carbonylation reaction. However, it is generally difficult to control the distribution of aluminum in the existing synthesis technology. In addition, mordenite with low Si/Al ratio has some obvious deficiencies in practical application, such as poor hydrothermal stability, easy carbon deposition and deactivation, etc. Therefore, it is of great significance to prepare mordenite with high silicon 8-membered ring pore acid content.

SUMMARY OF THE INVENTION

According to one aspect of the present application, there is provided a mordenite molecular sieve, which is prepared from a dual template agent, on the one hand, a high silicon-to-aluminum ratio can be obtained, and on the one hand, the acid center of the 8-membered ring channel of the mordenite molecular sieve accounts for the total The proportion of B acid centers can be flexibly adjusted within a relatively concentrated range (60-80%).

A mordenite molecular sieve, wherein the mordenite molecular sieve is selected from any of the substances having the chemical formula shown in formula I;

R _a Q _b M _c (S _x A _ly )O ₂ formula I

In the formula I, R is the first templating agent, and R is selected from any one of tetramethyldiamine compounds;

Q is the second templating agent, and Q is selected from any one of the cyclohexylamine compounds;

M is an alkali metal ion;

a represents the number of moles of the first templating agent R corresponding to each mole of ( _SixAly )O ₂ , and the value range of a is _{0.005≤a≤0.05} ;

b represents the number of moles of the second template Q corresponding to each mole of ( _SixAly )O ₂ , and the value range of b is _{0.005≤b≤0.05} ;

c represents the number of moles of alkali metal ions M corresponding to each mole of (Six _Aly )O ₂ , and the value range of c is _{0.02≤c≤0.1} ;

x and y represent the mole fractions of Si and Al, respectively, and the ranges are 0.80≤x≤0.97, 0.03≤y≤0.2, and x+y=1.

Preferably, the value range of x is 0.90≤x≤0.95;

Preferably, the value range of y is 0.05≤y≤0.1.

Optionally, the tetramethyldiamine compound is selected from any of the substances having the structural formula shown in formula II;

In the formula II, R ₀ represents a C ₁ -C ₁₀ alkyl group.

Preferably, the tetramethyldiamine compound is selected from tetramethylmethanediamine, tetramethylethylenediamine, tetramethylpropylenediamine, tetramethylbutanediamine, tetramethylpentanediamine, tetramethylethylenediamine Any one of methylhexamethylenediamine, tetramethylheptanediamine, and tetramethyloctanediamine.

Optionally, the cyclohexylamine compound is selected from any one of the substances having the structural formula shown in formula III;

In the formula III, R ₁ and R ₂ are independently selected from any one of H and C ₁ -C ₃ alkyl groups.

Preferably, the cyclohexylamine compound is selected from any one of cyclohexylamine, N-methylcyclohexylamine, N-ethylcyclohexylamine and 2-methylcyclohexylamine.

Optionally, the silicon-aluminum ratio of the mordenite molecular sieve is n, and the value range of n is 10≤n≤60; wherein, the silicon-aluminum ratio is SiO ₂ /Al ₂ O ₃ .

Specifically, the upper limit of the value range of the silicon-alumina ratio n of the mordenite molecular sieve is selected from 12.90, 19.20, 19.60, 20.90, 21.40, 23.70, 25.30, 26.50, 27.40, 28.40, 31.80, 33.40, 34.20, 37.70, 38.10, 39.40 , any value in 40.30, 41.30, 52.50, 57.10, 60.0; the lower limit of the value range of the silicon-aluminum ratio n of the mordenite molecular sieve is selected from 10, 12.90, 19.20, 19.60, 20.90, 21.40, 23.70, 25.30, 26.50, 27.40 , 28.40, 31.80, 33.40, 34.20, 37.70, 38.10, 39.40, 40.30, 41.30, 52.50, 57.10.

Preferably, the silicon-alumina ratio of the mordenite molecular sieve is n, and the value range of n is 16≤n≤50. When the value range of n is 16≤n≤50, the conversion rate of dimethyl ether (abbreviated as DME) is greater than 70%, and the selectivity of methyl acetate is greater than 98%.

Further preferably, the silicon-alumina ratio of the mordenite molecular sieve is n, and the value range of n is 20≤n≤35.

When the value range of n is 20≤n≤35, the conversion rate of dimethyl ether (abbreviated as DME) is greater than 88%, and the selectivity of methyl acetate is greater than 99%.

Optionally, the number of B acid centers in the 8-membered ring channel of the mordenite molecular sieve accounts for 60% to 80% of the total number of B acid centers of the mordenite molecular sieve.

Specifically, the upper limit of the proportion of B acid centers in the 8-membered ring channel is selected from 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 74%, 75%, 77% %, 78%, and 80%; the lower limit of the proportion of B acid centers in the 8-membered ring channel is selected from 60%, 63%, 64%, 65%, 66%, 67%, 68%, 69 Any of %, 70%, 74%, 75%, 77%, 78%.

Optionally, the alkali metal ions include Na ⁺ and/or K ⁺ .

According to the second aspect of the present application, there is provided a method for preparing the mordenite molecular sieve according to any one of the above, wherein the preparation method comprises:

Crystallizing the initial gel mixture containing silicon source, aluminum source, alkali source, first templating agent R, second templating agent Q, seed crystal and water to obtain the mordenite molecular sieve;

Wherein, the first templating agent R is selected from any one of tetramethyldiamine compounds;

The second templating agent Q is selected from any one of cyclohexylamine compounds;

The alkali source contains alkali metal ions.

Optionally, the silicon source is selected from at least one of silica sol, silica powder, methyl orthosilicate, ethyl orthosilicate, silica, and water glass.

Preferably, the silicon source is silica or silica sol.

Optionally, the aluminum source is selected from at least one of aluminum isopropoxide, aluminum oxide, aluminum hydroxide, aluminum chloride, aluminum sulfate, aluminum nitrate, and sodium aluminate.

Preferably, the aluminum source is sodium aluminate, aluminum nitrate, and aluminum oxide.

Optionally, the alkali source includes any one of sodium hydroxide and potassium hydroxide.

Preferably, the alkali source is sodium hydroxide.

Optionally, the seed crystal is mordenite. In this application, the silicon-alumina ratio of the seed mordenite is not strictly limited.

The seed mordenite in the present application can be obtained by any suitable method in the prior art.

Optionally, in the initial gel mixture, the molar ratio of each component is as follows:

SiO ₂ /Al ₂ O ₃ =20～150;

M ₂ O/SiO ₂ =0.03～0.30, wherein M is an alkali metal ion;

R/SiO ₂ =0.05～0.50, R is the first templating agent;

Q/SiO ₂ =0.05～0.50, Q is the second templating agent;

H ₂ O/SiO ₂ =7～30;

The amount of seed crystals added is 0.1-5wt% of the solid content of _SiO2 in the raw material.

Specifically, the upper limit of the range of the molar ratio of SiO ₂ /Al ₂ O ₃ is selected from any value among 24, 25, 30, 33.3, 37.5, 50, 60, 100, 120, and 150; SiO ₂ /Al ₂ O ₃ The lower limit of the range of the molar ratio is selected from any value of 20, 24, 25, 30, 33.3, 37.5, 50, 60, 100, 120.

Specifically, the upper limit of the range of the molar ratio of M ₂ O/SiO ₂ is selected from any value among 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.153, 0.16, and _{0.3 ;} The lower end of the range is selected from any of 0.03, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.153, 0.16.

The upper limit of the range of the molar ratio of R/SiO ₂ is selected from any value of 0.1, 0.15, 0.2, and 0.5; the lower limit of the range of the molar ratio of R/SiO ₂ is selected from any value of 0.05, 0.1, 0.15, and 0.2.

The upper limit of the range of the molar ratio of Q/SiO ₂ is selected from any value of 0.067, 0.1, 0.2, and 0.5; the lower limit of the range of the molar ratio of Q/SiO ₂ is selected from any value of 0.05, 0.067, 0.1, and 0.2.

Specifically, the upper limit of the range of the molar ratio of H ₂ O/SiO ₂ is selected from any value among 10, 12.67, 14, 15, 18.67, 20, and 30; the lower limit of the range of the molar ratio of H ₂ O/SiO ₂ is selected from Any value from 7, 10, 12.67, 14, 15, 18.67, 20.

Specifically, the amount of seed crystals added is any value selected from 1wt%, 2wt%, 4wt% and 5wt% of the upper limit of the total solid weight of the raw material mixture; the amount of seed crystals added is the lower limit of the total solid weight of the raw material mixture selected from 0.1wt% , 1 wt %, 2 wt %, and any value of 4 wt %.

Optionally, R/SiO ₂ =0.05-0.2, and R is the first templating agent.

Optionally, Q/SiO ₂ =0.05-0.2, and Q is the second templating agent.

Preferably, in the initial gel mixture, the molar ratio of each component is as follows:

SiO ₂ /Al ₂ O ₃ =24～120;

M ₂ O/SiO ₂ =0.03～0.30, wherein M is an alkali metal ion;

R/SiO ₂ =0.05～0.20, R is the first templating agent;

Q/SiO ₂ =0.05～0.20, Q is the second templating agent;

H ₂ O/SiO ₂ =7～30;

The amount of seed crystals added is 1-5wt% of the solid content of _SiO2 in the raw material.

In this range, the silicon-alumina ratio of the mordenite molecular sieve is n, and the value range of n is 20≤n≤35.

Optionally, the initial gel mixture is prepared by at least the following method:

The aluminum source is mixed with deionized water, followed by adding the alkali metal source, the first templating agent R, the second templating agent Q, the silicon source, and the seed crystal, and stirring at room temperature to obtain the initial gel mixture.

Optionally, the crystallization conditions include: crystallization temperature of 120-200° C., crystallization under self-boosting for 8-144 hours.

The upper limit of the crystallization temperature is selected from any value of 130°C, 140°C, 150°C, 160°C, 170°C, 175°C, 180°C, and 200°C; the lower limit of the crystallization time temperature is selected from 120°C, 130°C, 140°C Any value of °C, 150°C, 160°C, 170°C, 175°C, and 180°C.

The upper limit of the crystallization time is selected from any value in 10h, 15h, 20h, 30h, 40h, 48h, 60h, 96h, 120h, 144h; the lower limit of the crystallization time is selected from 8h, 10h, 15h, 20h, 30h, 40h, 48h , 60h, 96h, 120h any value.

According to the third aspect of the present application, a catalyst is also provided, the catalyst is prepared from at least one of the mordenite molecular sieve described in any of the above and the mordenite molecular sieve obtained by the preparation method described in any of the above-mentioned preparation methods. .

Optionally, the catalyst is obtained from mordenite molecular sieve through ammonium ion exchange and calcination in air at 400-700°C.

According to the fourth aspect of the present application, a method for preparing methyl acetate by carbonylation of dimethyl ether is also provided. The methyl acetate can be obtained by contacting and reacting a mixture containing dimethyl ether and carbon monoxide with a catalyst. ;

Wherein, the catalyst is selected from at least one of the above-mentioned catalysts.

Optionally, the conditions of the reaction are:

The volume ratio of dimethyl ether and carbon monoxide is 1:1 to 20;

The space velocity under the standard condition of the mixture is 2500～4000ml g ^-1 h ^-1 ;

The reaction temperature is 180～220 ℃;

The reaction time is 2.5～3.5h.

In the present application, the subscripts in "C ₁ -C ₁₀ " all represent the number of carbon atoms contained in the group. For example, C ₁ -C ₁₀ alkyl means an alkyl group having 1 to 10 carbon atoms, and C ₁ alkyl means an alkyl group having 1 carbon atom.

The beneficial effects that this application can produce include:

1) The mordenite provided by the application is synthesized by dual template agents, and can have a higher silicon-alumina ratio, thereby improving the stability of the molecular sieve, and the number of B acid centers in the 8-membered ring channel of the molecular sieve is the same as the total B acid of the mordenite molecular sieve. The proportion of the number of centers is 60% to 80%. Through the synthesis method provided in this application, the proportion of the number of B acid centers in the 8-membered ring channel in the total number of B acid centers in the mordenite molecular sieve is regulated;

2) The mordenite provided by this application, the MOR molecular sieve containing double organic amine template agent, can have a higher silicon-aluminum ratio of 10-60, and can regulate the distribution of the number of B acid centers in the 8-membered ring channel;

3) In the MOR molecular sieve obtained by the technical solution of the present invention, the ratio of the acid center of the 8-membered ring channel to the total B acid center can be flexibly adjusted within a certain range (60-80%);

4) the preparation method of the mordenite provided by the application, the technique is simple, and is conducive to large-scale industrial production;

5) The prepared MOR molecular sieve exhibits excellent catalytic performance in the catalytic reaction of dimethyl ether carbonylation (the conversion rate of DME can reach 89%, and the selectivity of methyl acetate can reach 99%).

Description of drawings

Fig. 1 is the X-ray diffraction pattern of molecular sieve sample 1;

Fig. 2 is the infrared spectrum of molecular sieve sample 1;

Fig. 3 is the scanning electron microscope picture of molecular sieve sample 2;

Fig. 4 is the catalytic performance figure in the process of preparing methyl acetate of the catalyst prepared by molecular sieve sample 2;

Fig. 5 is the X-ray diffraction pattern of the sample in Comparative Example 1;

Fig. 6 is the X-ray diffraction pattern of the sample in Comparative Example 2;

Fig. 7 is the X-ray diffraction pattern of the sample in Comparative Example 3;

Figure 8 is the X-ray diffraction pattern of the sample in Comparative Example 4;

Fig. 9 is the infrared spectrogram of the sample in Comparative Example 5;

Figure 10 is the infrared spectrogram of the sample in Comparative Example 6;

Figure 11 is the infrared spectrogram of the sample in Comparative Example 7;

Fig. 12 is the infrared spectrum of catalyst C1 prepared by molecular sieve sample 2;

FIG. 13 is an infrared spectrum of the sample catalyst C2 in Comparative Example 9. FIG.

Detailed ways

The present application will be described in detail below with reference to the examples, but the present application is not limited to these examples.

Possible implementations are described below.

The object of the present invention is to provide a kind of MOR molecular sieve, the anhydrous chemical composition of the molecular sieve is expressed as: R _a Q _b M _c (S _x A _ly )O ₂ , wherein: R is an organic amine, selected from tetramethylmethanediamine, In tetramethylethylenediamine, tetramethylpropylenediamine, tetramethylbutanediamine, tetramethylpentanediamine, tetramethylhexamethylenediamine, tetramethylheptanediamine, tetramethyloctanediamine any one; Q is an organic amine, selected from any one in cyclohexylamine, N-methylcyclohexylamine, N-ethylcyclohexylamine, 2-methylcyclohexylamine; M is a metal ion, Na ⁺ and/or K ⁺ ; a represents the number of moles of organic amine R corresponding to each mole of (Six _Aly )O ₂ , a ₌ 0.02-0.5; b represents the number of moles of organic amine P corresponding to each mole of ( _Six A _y )O ₂ Number of moles, b=0.02～0.5; c represents the number of moles of metal ions per mole of (SixAly)O ₂ , c=0.02～0.1; _x and _y represent the mole fractions of Si and Al, respectively, and the ranges are x=0.8-0.97, y=0.03-0.2, and x+y=1.

Another object of the present invention is to provide a method for synthesizing high-silicon mordenite.

Another object of the present invention is to provide a synthetic method for adjusting the distribution of mordenite acid.

Another object of the present invention is to provide an acid-catalyzed reaction catalyst for synthesizing MOR molecular sieve by the above-mentioned method and prepared therefrom.

The technical problem to be solved by the present invention is to synthesize pure-phase high-silicon MOR molecular sieves under hydrothermal conditions by using dual organic amines as structure-directing agents and using silicon sources, aluminum sources and alkali sources used in the synthesis of conventional molecular sieves as raw materials.

The preparation process of the present invention is as follows:

a) mixing silicon source, aluminum source, alkali source, templating agent R, water and seed crystal to form an initial gel mixture having the following molar ratio:

SiO ₂ /Al ₂ O ₃ =20-150;

M ₂ O/SiO ₂ =0.03-0.30, wherein M is an alkali metal;

R/SiO ₂ =0.05～0.50, R represents tetramethylmethanediamine, tetramethylethylenediamine, tetramethylpropylenediamine, tetramethylbutanediamine, tetramethylpentanediamine, tetramethylhexanediamine Any one in diamine, tetramethylheptanediamine, tetramethylheptanediamine;

Q/SiO ₂ =0.05～0.50, Q represents any one of template agent cyclohexylamine, N-methylcyclohexylamine, N-ethylcyclohexylamine, 2-methylcyclohexylamine;

H ₂ O/SiO ₂ =7～30;

The seed crystal is mordenite, and the added amount of the seed crystal is 0.1-5% of the total solid content of the raw material mixture;

b) crystallizing the initial gel mixture obtained in step a) at 120-180° C. for not less than 5 hours;

Described step a) templating agent R represents tetramethylmethanediamine, tetramethylethylenediamine, tetramethylpropylenediamine, tetramethylbutanediamine, tetramethylpentanediamine, tetramethylhexamethylenediamine , any one of tetramethylheptanediamine and tetramethylheptanediamine.

Described step a) templating agent Q represents any one in cyclohexylamine, N-methylcyclohexylamine, N-ethylcyclohexylamine, 2-methylcyclohexylamine;

In the step a), the molar ratio R/SiO ₂ in the initial gel mixture is 0.05-0.50.

The crystallization temperature in the step b) is 120-180°C.

The crystallization time in the step b) is 5-144 hours.

In the step a), the silicon source is selected from at least one of silica sol, silica gel, methyl orthosilicate, ethyl orthosilicate, silica, and water glass.

In the step a), the aluminum source is selected from at least one of aluminum isopropoxide, aluminum oxide, aluminum hydroxide, aluminum chloride, aluminum sulfate, aluminum nitrate, and sodium aluminate.

The alkali source in the step a) is sodium hydroxide and/or potassium hydroxide.

The seed crystal of step a) is mordenite.

The present invention also relates to a catalyst for acid-catalyzed reaction, which is obtained by calcining the above-mentioned MOR molecular sieve or the MOR molecular sieve synthesized according to the above-mentioned method in air at 400-700°C.

Unless otherwise specified, the raw materials and catalysts in the examples of this application are purchased through commercial channels and used directly without any special treatment.

The analytical method in the embodiment of the application is as follows:

The elemental composition was determined by a Magix 2424 X-ray fluorescence analyzer (XRF) from Philips.

X-ray powder diffraction phase analysis (XRD) used X'Pert PRO X-ray diffractometer from PANalytical, the Netherlands, Cu target, Kα radiation source (λ=0.15418nm), voltage 40KV, current 40mA.

The instrument used for scanning electron microscope (SEM) test was a Hitachi SU8020 field emission scanning electron microscope with an accelerating voltage of 2 kV.

Infrared transmission spectroscopy (FTIR) experiments were carried out in a vacuum system, the samples were dehydrated at 450°C, and spectra were collected at room temperature.

Gas sample analysis was carried out on-line analysis by using Agilent's 6890GC gas chromatograph, and the chromatographic column was Agilent's HP-5 capillary column.

Conversion rate of dimethyl ether=[(carbon moles of dimethyl ether in mixed gas)-(carbon moles of dimethyl ether in product)]/(carbon moles of dimethyl ether in mixed gas)*100%

Selectivity of methyl acetate=(2/3)*(carbon moles of methyl acetate in product)/[(carbon moles of dimethyl ether in mixed gas)-(carbon moles of dimethyl ether in product) ]*100%

In the examples of this application, the preparation method of seed mordenite is referred to GJ Kim, WSAhn, Direct synthesis and characterization of high-SiO ₂ -content mordenites, Zeolites 11 (1991) 745-750.

Example 1

The molar proportions of each raw material and the crystallization conditions are shown in Table 1. First, 1.643g of sodium aluminate was added to 35g of deionized water, and then 1.617g of sodium hydroxide was added to it. After mixing evenly, 1g of tetramethylmethanediamine, 2g of cyclohexylamine, 40g of silica sol, and 0.25g of seed crystals were added. Continue stirring at room temperature until a homogeneous initial gel forms. The gel was put into a stainless steel reactor with a polytetrafluoroethylene lining, and the temperature was raised to 160 °C for crystallization for 30 h. The obtained solid product was centrifuged, washed with deionized water until neutral, and dried in air at 110 °C to obtain The original powder, recorded as sample 1#.

XRD analysis of the product shows that the synthesized product has the characteristics of MOR structure (see Figure 1 for the XRD spectrum). The elemental composition of the molecular sieve product was analyzed by XRF and CHN, and the results are listed in Table 1. The bulk silicon to aluminum ratio (SiO ₂ /Al ₂ O ₃ ) of the sample of Example 1 was 19.6. The hydrogen-type infrared spectrum of the obtained sample was measured, and according to the literature (JACS, 2007, 129, 4919-4924), the bridging hydroxyl group near 3605cm ^-1 was subjected to peak fitting, and the results showed that the sample 8-membered ring pore B acid accounted for the total B acid The percentage of amount is 68% (see Figure 2 for the results of infrared spectrum peaks).

The chemical formula of the mordenite molecular sieve synthesized in Example 1 is shown in Table 2.

Example 2-20

The specific batching ratio and crystallization conditions are shown in Table 1, and the specific batching process is the same as that in Example 1.

The synthesized sample is analyzed by XRD, and the X-ray diffraction spectrum of the product has the characteristics of Fig. 1, which is proved to be a mordenite molecular sieve.

The elemental composition of the molecular sieve product phase was analyzed by XRF, and the silicon-aluminum ratio was listed in Table 1.

The hydrogen-type infrared spectrum of the obtained sample was measured, and according to the literature (JACS, 2007, 129, 4919-4924), the bridging hydroxyl group near 3610 cm ^-1 was subjected to peak fitting, and the percentage of B acid in the 8-membered ring pore in the total B acid was obtained. , listed in Table 1.

Table 1 Molecular sieve synthesis ingredients and crystallization conditions*

Note*: Silicon source: a means silica sol; b means white carbon black; c means water glass; d means ethyl orthosilicate.

Aluminum source: I represents sodium aluminate; II represents aluminum oxide; III represents aluminum nitrate; IV represents aluminum isopropoxide.

Template R: A represents tetramethylmethanediamine; B represents tetramethylethylenediamine; C represents tetramethylpropylenediamine; D represents tetramethylbutanediamine; E represents tetramethylpentanediamine; F Represents tetramethylhexamethylenediamine; G represents tetramethylheptanediamine; H represents tetramethyloctanediamine.

Template Q: J represents cyclohexylamine, K represents N-methylcyclohexylamine, L represents N-ethylcyclohexylamine, and M represents 2-methylcyclohexylamine.

Note**: The ratio of Na ₂ O is calculated based on the total amount of metal oxide Na ₂ O contained in the added aluminum source, silicon source and alkali source.

Note***: The calculation method of the seed crystal is: the weight of the seed crystal/the _SiO2 solid content in the raw material.

Table 2 Anhydrous chemical composition of mordenite molecular sieves

Example 21

Except replacing sodium hydroxide with potassium hydroxide, other batching ratios and batching processes, and crystallization conditions are the same as those in Example 9. The product is analyzed by XRD, and the X-ray diffraction spectrum of the product has the characteristics of Figure 1, which proves that it is a mordenite molecular sieve.

Example 22

Take 3 g of the synthetic sample of Example 2, put it into a plastic beaker, add 3 mL of 40% hydrofluoric acid solution to dissolve the molecular sieve skeleton under ice-water bath conditions, and then add 15 mL of chloroform to dissolve the organic matter therein. The composition of the organic matter was analyzed by GC-MS, and the organic matter contained therein was found to be tetramethylhexamethylenediamine and cyclohexylamine.

Example 23

The samples obtained in Example 2 were characterized by scanning electron microscopy. The scanning electron microscope image of the sample is shown in Figure 3.

It can be seen from Figure 3 that the sample has a bulk morphology.

Example 24

The molecular sieve sample in Example 2 was calcined in air (550° C., 4 h) to obtain Na-MOR. The calcined sample was placed in a beaker, and 1 mol/L ammonium nitrate solution was added to the beaker to conduct ammonia ion exchange for 4 hours at 80 °C, wherein the solid-liquid ratio of Na-MOR molecular sieve and ammonium nitrate solution was 1: 10. After repeating the ammonia ion exchange three times, drying at 120°C for 8 hours, calcining it in the air at 550°C for 4 hours, pressing and crushing to 40-60 mesh, which is recorded as catalyst C1. 1.0 g of catalyst C1 was weighed and evaluated in a fixed bed reactor for the carbonylation reaction of dimethyl ether (abbreviated as DME). At the beginning of the reaction, nitrogen was activated at 400 °C for 1 h, and then the temperature was lowered to 300 °C. Pyridine was passed into the reactor at a gas flow rate of 30 ml/min for 1 h, followed by a nitrogen purge for 1 h (30 ml/min). Finally, the temperature was lowered to 200°C for the reaction. Mixed gas (DME/CO/N ₂ =2/14/84, volume ratio), the gas space velocity is 3000ml g ^-1 h ^-1 (STP), and the reaction pressure is 2.0Mpa. After the reaction reached equilibrium (about 6 h) the conversion of DME was 88% and the methyl acetate selectivity was greater than 99.9% (see Figure 4).

Examples 25-28

Except for the selected molecular sieve catalyst samples, the catalyst preparation method and the pyridine treatment method are the same as those in Example 24. The specific reaction conditions are shown in Table 3.

Table 3 Catalyst and reaction situation

Example 29

Catalyst C1 was characterized by infrared, and the corresponding hydroxyl spectrum was shown in Figure 12.

Comparative Example 1

Except that the organic templating agent R and the organic templating agent Q are not added, the proportions of other ingredients, the ingredient process, and the crystallization conditions are the same as those in Example 2. The obtained product was identified as a mixture of MOR and ZSM-5 by XRD (see Figure 5 for the XRD spectrum).

Comparative Example 2

Except that the organic templating agent R and the organic templating agent Q are not added, the proportions of other ingredients, the ingredient process, and the crystallization conditions are the same as those in Example 4. The obtained product was identified as ZSM-5 by XRD (see Figure 6 for the XRD spectrum).

Comparative Example 3

Except that the organic template agent R is not added, other batching ratios, batching processes, and crystallization conditions are the same as in Example 4. The obtained product was identified as a mixture of MOR and ZSM-5 by XRD (see Figure 7 for the XRD spectrum).

Comparative Example 4

Except that the organic templating agent Q is not added, other batching ratios, batching processes, and crystallization conditions are the same as in Example 4. The obtained product was identified as a mixture of MOR and ZSM-5 by XRD (see Figure 8 for the XRD spectrum).

Comparative Example 5

Except that the organic templating agent R and the organic templating agent Q are not added, other proportions of ingredients, ingredient process, and crystallization conditions are the same as in Example 10. The obtained product was identified as MOR by XRD, the product silicon-aluminum ratio (SiO ₂ /Al ₂ O ₃ ) was 18.2, and the ratio of 8-membered ring pore B acid to the total B acid amount was 48% (see Figure 9 for the peak separation results of the infrared spectrum). ).

Comparative Example 6

Except that the organic template agent Q is not added, other proportions, batching process, and crystallization conditions are the same as those in Example 13. The obtained product was identified as MOR by XRD, the silicon-aluminum ratio (SiO ₂ /Al ₂ O ₃ ) of the product was 28.1, and the ratio of 8-membered ring pore B acid to the total B acid amount was 51% (see Figure 10 for the peaks of the infrared spectrum). ).

Comparative Example 7

Except that the organic template agent Q is not added, other proportions, batching process, and crystallization conditions are the same as in Example 15. The obtained product was identified as MOR by XRD, the product silicon-aluminum ratio (SiO ₂ /Al ₂ O ₃ ) was 25.4, and the ratio of 8-membered ring pore B acid to the total B acid amount was 47% (see Figure 11 for the peak separation results of the infrared spectrum). ).

Comparative Example 8

Except that the organic template agent Q is not added, other proportions, batching process, and crystallization conditions are the same as those in Example 2. The obtained product was identified as MOR by XRD, the product silicon-aluminum ratio (SiO ₂ /Al ₂ O ₃ ) was 34.7, and the ratio of 8-membered ring pore B acid to total B acid was 49%.

The sample in Comparative Example 8 was subjected to NH ₄ NO ₃ ion exchange to remove sodium ions (the same treatment method as in Example 24), calcined in air at 550° C. for 4 hours, pressed into tablets, and crushed to 40-60 mesh, which was recorded as catalyst C2 . Weigh 1.0 g of catalyst C2 in a fixed-bed reactor for evaluation of dimethyl ether (abbreviated as DME) carbonylation reaction. At the beginning of the reaction, nitrogen was activated at 400 °C for 1 h, and then the temperature was lowered to 300 °C. Pyridine was passed into the reactor at a gas flow rate of 30 ml/min for 1 h, followed by a nitrogen purge for 1 h (30 ml/min). Finally, the temperature was lowered to 200°C for the reaction. Mixed gas (DME/CO/N ₂ =2/14/84, volume ratio), the gas space velocity is 3000ml g ^-1 h ^-1 (STP), and the reaction pressure is 2.0Mpa. After a 6-h induction period, samples were taken to obtain the conversion of DME and the selectivity of methyl acetate in the product. The conversion of DME was 52% and the methyl acetate selectivity was 99%.

Comparative Example 9

According to the document WSAhn, Direct synthesis and characterization of high-SiO ₂ -content mordenites, Zeolites 11 (1991) 745-750. Synthesis of MOR molecular sieves with a silicon-aluminum ratio (SiO ₂ /Al ₂ O ₃ ) of 12.6. The obtained molecular sieve was prepared by referring to the method for preparing catalyst C1 in Example 24 to obtain catalyst C2. Catalyst C2 was characterized by infrared, and the corresponding hydroxyl spectrum was shown in Figure 13. Comparing the hydroxyl spectra of catalysts C1 and C2, it can be seen that the C2 catalyst has more aluminum hydroxyl groups, indicating that the catalyst dealumination is more serious and the thermal stability of the catalyst is worse.

The above are only a few embodiments of the present application, and are not intended to limit the present application in any form. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Without departing from the scope of the technical solutions of the present application, any changes or modifications made by using the technical contents disclosed above are equivalent to equivalent implementation cases and fall within the scope of the technical solutions.

Claims (22)

A mordenite molecular sieve, characterized in that the mordenite molecular sieve is selected from any of the substances having the anhydrous chemical formula shown in formula I; R _a Q _b M _c (S _x A _ly )O ₂ formula I In the formula I, R is the first templating agent, and R is selected from any one of tetramethyldiamine compounds; Q is the second templating agent, and Q is selected from any one of the cyclohexylamine compounds; M is an alkali metal ion; a represents the number of moles of the first templating agent R corresponding to each mole of ( _SixAly )O ₂ , and the value range of a is _{0.005≤a≤0.05} ; b represents the number of moles of the second template Q corresponding to each mole of ( _SixAly )O ₂ , and the value range of b is _{0.005≤b≤0.05} ; c represents the number of moles of alkali metal ions M corresponding to each mole of (Six _Aly )O ₂ , and the value range of c is _{0.02≤c≤0.1} ; x and y represent the mole fractions of Si and Al, respectively, and the ranges are 0.80≤x≤0.97, 0.03≤y≤0.2, and x+y=1. The mordenite molecular sieve according to claim 1, wherein the tetramethyldiamine compound is selected from any of the substances having the structural formula shown in formula II;

In the formula II, R ₀ represents a C ₁ -C ₁₀ alkyl group. The mordenite molecular sieve according to claim 2, wherein the tetramethyldiamine compound is selected from the group consisting of tetramethylmethanediamine, tetramethylethylenediamine, tetramethylpropylenediamine, tetramethylethylenediamine Any one of butanediamine, tetramethylpentanediamine, tetramethylhexamethylenediamine, tetramethylheptanediamine, and tetramethyloctanediamine. The mordenite molecular sieve according to claim 1, wherein the cyclohexylamine compound is selected from any one of the substances having the structural formula shown in formula III;

In the formula III, R ₁ and R ₂ are independently selected from any one of H and C ₁ -C ₃ alkyl groups. The mordenite molecular sieve according to claim 4, wherein the cyclohexylamine compound is selected from the group consisting of cyclohexylamine, N-methylcyclohexylamine, N-ethylcyclohexylamine, 2-methylcyclohexylamine Any of the amines. The mordenite molecular sieve according to claim 1, wherein the silicon-alumina ratio of the mordenite molecular sieve is n, and the value range of n is 10≤n≤60; Wherein, the silicon-aluminum ratio is a molar ratio of SiO ₂ /Al ₂ O ₃ . The mordenite molecular sieve according to claim 1, wherein the number of B acid centers in the 8-membered ring channel of the mordenite molecular sieve accounts for 60% to 80% of the total number of B acid centers in the mordenite molecular sieve. %. The mordenite molecular sieve according to claim 1, wherein the alkali metal ions comprise Na ⁺ and/or K ⁺ . The preparation method of the mordenite molecular sieve according to any one of claims 1 to 8, wherein the preparation method comprises: Crystallizing the initial gel mixture containing silicon source, aluminum source, alkali source, first templating agent R, second templating agent Q, seed crystal and water to obtain the mordenite molecular sieve; Wherein, the first templating agent R is selected from any one of tetramethyldiamine compounds; The second templating agent Q is selected from any one of cyclohexylamine compounds; The alkali source contains alkali metal ions. The preparation method according to claim 9, wherein the silicon source is selected from at least one of silica sol, silica powder, methyl orthosilicate, ethyl orthosilicate, silica, and water glass kind. The preparation method according to claim 9, wherein the aluminum source is selected from at least one of aluminum isopropoxide, aluminum oxide, aluminum hydroxide, aluminum chloride, aluminum sulfate, aluminum nitrate, and sodium aluminate . The preparation method according to claim 9, wherein the alkali source comprises any one of sodium hydroxide and potassium hydroxide. The preparation method according to claim 9, wherein the seed crystal is mordenite. The preparation method according to claim 9, wherein, in the initial gel mixture, the molar ratio of each component is as follows: SiO ₂ /Al ₂ O ₃ =20～150; M ₂ O/SiO ₂ =0.03～0.30, wherein M is an alkali metal ion; R/SiO ₂ =0.05～0.50, R is the first templating agent; Q/SiO ₂ =0.05～0.50, Q is the second templating agent; H ₂ O/SiO ₂ =7～30; The amount of seed crystals added is 0.1-5% of the solid content of the raw material SiO ₂ . The preparation method according to claim 9, characterized in that, R/SiO ₂ =0.05-0.2, and R is the first templating agent. The preparation method according to claim 9, characterized in that, Q/SiO ₂ =0.05-0.2, and Q is the second templating agent. The preparation method according to claim 9, wherein the initial gel mixture is prepared by at least the following method: The aluminum source is mixed with deionized water, followed by adding the alkali metal source, the first templating agent R, the second templating agent Q, the silicon source, and the seed crystal, and stirring at room temperature to obtain the initial gel mixture. The preparation method according to claim 9, wherein the crystallization conditions include: a crystallization temperature of 120-200° C., and a self-boosted crystallization for 8-144 hours. A catalyst, characterized in that the catalyst is prepared from at least one of the mordenite molecular sieve according to any one of claims 1 to 8 and the mordenite molecular sieve obtained by the preparation method according to any one of claims 9 to 18 get. The catalyst according to claim 19, wherein the catalyst is obtained from mordenite molecular sieve through ammonium ion exchange and calcination in air at 400-700°C. A method for preparing methyl acetate by carbonylation of dimethyl ether, characterized in that the methyl acetate can be obtained by contacting and reacting a mixture containing dimethyl ether and carbon monoxide with a catalyst; Wherein, the catalyst is selected from at least one of the catalysts of claim 19 or 20. method according to claim 21, is characterized in that, the condition of described reaction is: The volume ratio of dimethyl ether and carbon monoxide is 1:1 to 20; The space velocity under the standard condition of the mixture is 2500～4000ml g ^-1 h ^-1 ; The reaction temperature is 180～220 ℃; The reaction pressure is 0.5 to 4 MPa.

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