A modified clay mesoporous composite material catalyst, its preparation method and application

Abstract

This invention belongs to the field of catalyst technology and discloses a modified clay mesoporous composite catalyst, its preparation method, and its application. The preparation method includes: (1) crystallizing a mesoporous silica precursor solution containing a template agent, a silicon source, and a pore-expanding agent to obtain a mesoporous silica filter cake; (2) mixing the mesoporous silica filter cake, clay minerals, and a first dispersant to obtain a clay mesoporous composite slurry; then, selectively diluting the clay mesoporous composite slurry and drying it to obtain a clay mesoporous composite material; (3) mixing the clay mesoporous composite material with an acid solution to obtain a modified clay mesoporous composite catalyst. The catalyst provided by this invention can achieve a stable conversion of isopropanol to isopropyl ether with high conversion rate and high selectivity.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and more specifically, to a modified clay mesoporous composite catalyst, its preparation method, and its application. Background Technology

[0002] Isopropyl ether is widely used in gasoline refining, industrial feedstock extraction, and environmental protection. Currently, my country has a huge demand for isopropyl ether. The process conditions and flow of the isopropanol dehydration synthesis method are relatively simple, with high conversion rate and selectivity, thus showing good application prospects.

[0003] Currently, commonly used catalysts for the dehydration of isopropanol to produce isopropyl ether include sulfuric acid, ion exchange resins, and montmorillonite. Sulfuric acid catalysts corrode equipment and pollute the environment, and the product, isopropyl ether, is easily decomposed in sulfuric acid, making catalyst reuse difficult. Ion exchange resins are not heat-resistant, limiting their performance. While montmorillonite has good intrinsic advantages in the dehydration of isopropanol to produce isopropyl ether, it lacks abundant internal pores, and its pore structure is disordered with small pore volumes, hindering mass transfer of reactants and inhibiting catalytic activity. Furthermore, the unique binding properties of montmorillonite make granulation difficult, limiting its practical application. In addition, it is sensitive to reaction temperature and has poor long-cycle stability, typically only suitable for single-use. Therefore, the development of high-performance isopropanol dehydration catalysts is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to provide a modified clay mesoporous composite catalyst, its preparation method, and its application. The modified clay mesoporous composite catalyst of this invention has abundant mesoporous structures and acid center sites. When applied to the dehydration reaction of isopropanol, it exhibits excellent catalytic performance in the dehydration of isopropanol to isopropyl ether.

[0005] To achieve the above objectives, a first aspect of the present invention provides a method for preparing a modified clay mesoporous composite catalyst, the method comprising:

[0006] (1) Crystallize the mesoporous silica precursor solution containing template agent, silicon source and pore expander to obtain mesoporous silica filter cake.

[0007] (2) The mesoporous silica filter cake, clay minerals and the first dispersant are mixed to obtain a clay mesoporous composite slurry; then the clay mesoporous composite slurry is optionally diluted and dried to obtain a clay mesoporous composite material.

[0008] (3) The clay mesoporous composite material is mixed with an acid solution to obtain a modified clay mesoporous composite material catalyst.

[0009] A second aspect of the present invention provides a modified clay mesoporous composite catalyst prepared by the above-described preparation method.

[0010] A third aspect of the present invention provides the application of the above-described modified clay mesoporous composite catalyst as a catalyst for the preparation of isopropyl ether by the isopropanol dehydration method.

[0011] The technical solution of the present invention has the following beneficial effects:

[0012] (1) The catalyst provided by the present invention has a rich mesoporous structure and a high specific surface area, which effectively promotes the mass transfer of reactants and the diffusion of products.

[0013] (2) The catalyst provided by the present invention can achieve stable conversion of isopropanol to isopropyl ether with high conversion rate and high selectivity. The isopropanol conversion rate can reach more than 40%, the isopropyl ether selectivity can reach more than 85%, and it has good long-term cycle stability.

[0014] (3) The modification method of the modified clay mesoporous composite material catalyst provided by the present invention can effectively improve the catalytic activity of the clay mesoporous composite material and can achieve stable large-scale preparation of the modified clay mesoporous composite material catalyst.

[0015] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0016] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0017] Figure 1 The X-ray powder diffraction pattern of the modified clay mesoporous composite catalyst according to Example 1 of the present invention is shown. Here, intensity represents peak intensity, and degree represents degree.

[0018] Figure 2 The nitrogen uptake curves of the modified clay mesoporous composite catalyst according to Example 1 of the present invention are shown. Here, N2 uptake represents the amount of nitrogen adsorbed.

[0019] Figure 3 A pore size distribution curve of the modified clay mesoporous composite catalyst according to Example 1 of the present invention is shown. Here, pore width represents the pore size.

[0020] Figure 4 A scanning electron microscope image of the modified clay mesoporous composite catalyst according to Example 1 of the present invention is shown.

[0021] Figure 5The ammonia-temperature-programmed desorption curve of the modified clay mesoporous composite catalyst according to Example 1 of the present invention is shown. Here, intensity represents peak intensity, and temperature represents temperature.

[0022] Figure 6 The NMR spectrum of the post-catalytic liquid-phase product of the modified clay mesoporous composite catalyst according to Example 1 of the present invention is shown. Wherein, IPA represents isopropanol, IPE represents isopropyl ether, DMSO represents dimethyl sulfoxide, and Chemicalshift represents chemical shift.

[0023] Figure 7 The chromatogram of the gaseous products after catalysis of the modified clay mesoporous composite catalyst according to Example 1 of the present invention is shown. Wherein, Time represents time.

[0024] Figure 8 The diagram shows the isopropanol dehydration stability test of the modified clay mesoporous composite catalyst according to Example 1 of the present invention. Here, Conversion represents conversion rate, Selectivity represents selectivity, and Cycles represents cycles.

[0025] Figure 9 The X-ray powder diffraction pattern of the modified clay mesoporous composite catalyst according to Example 2 of the present invention is shown. Here, intensity represents peak intensity, and degree represents degree.

[0026] Figure 10 The nitrogen adsorption-desorption curves of the modified clay mesoporous composite catalyst according to Example 2 of the present invention are shown. Here, N2uptake represents the amount of nitrogen adsorbed.

[0027] Figure 11 A pore size distribution curve of the modified clay mesoporous composite catalyst according to Example 2 of the present invention is shown. Here, pore width represents the pore size.

[0028] Figure 12 The ammonia-temperature-programmed desorption curve of the modified clay mesoporous composite catalyst according to Example 2 of the present invention is shown. Here, intensity represents peak intensity, and temperature represents temperature.

[0029] Figure 13 The NMR spectrum of the post-catalytic liquid-phase product of the modified clay mesoporous composite catalyst according to Example 2 of the present invention is shown. In the figure, IPA represents isopropanol, IPE represents isopropyl ether, DMSO represents dimethyl sulfoxide, and Chemicalshift represents chemical shift.

[0030] Figure 14The chromatogram of the post-catalytic gas phase product of the modified clay mesoporous composite catalyst according to Example 2 of the present invention is shown. Wherein, Time represents time.

[0031] Figure 15 The X-ray powder diffraction pattern of the unmodified acid-modified clay mesoporous composite catalyst of Comparative Example 1 according to the present invention is shown. Here, intensity represents peak intensity, and degree represents degree.

[0032] Figure 16 The nitrogen adsorption-desorption curves of the unmodified acid-modified clay mesoporous composite catalyst of Comparative Example 1 according to the present invention are shown. Here, N2 uptake represents the amount of nitrogen adsorbed.

[0033] Figure 17 A pore size distribution curve of the unmodified clay mesoporous composite catalyst of Comparative Example 1 according to the present invention is shown. Here, pore width represents the pore size.

[0034] Figure 18 The ammonia-temperature-programmed desorption curves of the modified clay mesoporous composite catalysts of Examples 1 and 2 according to the present invention, and the unmodified clay mesoporous composite catalyst of Comparative Example 1 are shown. Here, intensity represents peak intensity, and temperature represents temperature.

[0035] Figure 19 The NMR spectrum of the post-catalytic liquid-phase product of the unmodified clay mesoporous composite catalyst of Comparative Example 1 according to the present invention is shown. In the figure, IPA represents isopropanol, IPE represents isopropyl ether, DMSO represents dimethyl sulfoxide, and Chemical shift represents chemical shift.

[0036] Figure 20 The chromatogram of the post-catalytic gas phase product of the unmodified clay mesoporous composite catalyst of Comparative Example 1 according to the present invention is shown. Wherein, Time represents time. Detailed Implementation

[0037] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0038] A first aspect of the present invention provides a method for preparing a modified clay mesoporous composite catalyst, the method comprising:

[0039] (1) Crystallize the mesoporous silica precursor solution containing template agent, silicon source and pore expander to obtain mesoporous silica filter cake.

[0040] (2) The mesoporous silica filter cake, clay minerals and the first dispersant are mixed to obtain a clay mesoporous composite slurry; then the clay mesoporous composite slurry is optionally diluted and dried to obtain a clay mesoporous composite material.

[0041] (3) The clay mesoporous composite material is mixed with an acid solution to obtain a modified clay mesoporous composite material catalyst.

[0042] According to the present invention, preferably, the mesoporous silica precursor solution containing a template agent, a silicon source, and a pore-expanding agent is prepared by a method comprising the following steps: uniformly mixing the template agent, the silicon source, the pore-expanding agent, and the second dispersant to obtain the mesoporous silica precursor solution;

[0043] The second dispersant comprises a buffer solution of acetic acid and sodium acetate with ethanol.

[0044] In one specific embodiment of the present invention, the template agent and the second dispersant are mixed evenly at 10-20°C; then the pore-expanding agent is added, and the mixture is stirred and mixed at 10-20°C for 6-10 hours; finally, the silicon source is added, and the mixture is stirred and mixed at 10-20°C for 18-22 hours to obtain the mesoporous silica precursor solution.

[0045] According to the present invention, preferably, in step (1), the template agent is a triblock copolymer of polyethylene oxide-propylene oxide-ethylene oxide;

[0046] The silicon source is tetraethyl orthosilicate (TEOS);

[0047] The pore-expanding agent is 3-methylpentane;

[0048] The crystallization temperature is 80℃~300℃, and the time is 12h~36h;

[0049] Preferably, the crystallization temperature is 100℃~150℃ and the time is 20h~24h.

[0050] In this invention, preferably, in step (1), after crystallization, the mixture is filtered and washed to obtain a mesoporous silica filter cake. After filtration and washing, the template agent is removed, resulting in a mesoporous silica filter cake with the template agent removed.

[0051] According to the present invention, preferably, in step (2), the clay mineral is at least one of sepiolite, illite, attapulgite and zeolite; preferably sepiolite and / or illite.

[0052] According to the present invention, preferably, in step (2), the mixing is ball milling mixing;

[0053] The mixing temperature is 15℃~80℃, and the time is 1h~100h; preferably, the mixing temperature is 60℃~70℃, and the time is 20~24h.

[0054] The first dispersant is water;

[0055] The mass ratio of the clay mineral to the mesoporous silica filter cake is (1-5):9;

[0056] In the clay-mesoporous composite slurry, the sum of the amounts of the mesoporous silica filter cake and clay minerals per liter of the first dispersant is 0.5 kg to 1.5 kg, preferably 0.5 kg to 1 kg.

[0057] In this invention, preferably, in step (2), the mixing is carried out in a ball mill jar, and both the ball mill jar and the grinding ball are made of agate.

[0058] According to the present invention, preferably, in step (2), the drying is spray drying, and more preferably centrifugal spray drying;

[0059] The inlet temperature of the spray dryer is 150℃~200℃, and the outlet temperature is 90~120℃;

[0060] The concentration of solids in the material used for drying is 10–50 wt%.

[0061] The spray drying is carried out in an atomizer with a rotation speed of 8000 rpm to 16000 rpm.

[0062] In this invention, in step (2), before drying, the clay mesoporous composite slurry can be diluted before drying, or dried directly without dilution, depending on the viscosity required for spray drying. The solvent used for dilution is water or ethanol.

[0063] According to the present invention, preferably, in step (3), the solid-liquid ratio of the clay mesoporous composite material to the acid solution is 1:(2-30)g / mL, more preferably 1:(10-20)g / mL;

[0064] The mixing temperature is 25–100°C, and the time is 0.5–36 h;

[0065] Preferably, the mixing temperature is 60–80°C and the mixing time is 8–10 hours;

[0066] Preferably, after mixing the clay mesoporous composite material with the acid solution, it is further washed and dried, and the drying temperature is 50-200℃, preferably 100-120℃.

[0067] In this invention, in step (3), mixing is preferably carried out in an oil bath at 25–100°C, and more preferably in an oil bath at 60–80°C. The washing is performed until the solution is neutral.

[0068] According to the present invention, preferably, in step (3), the acid solution is at least one of hydrochloric acid, sulfuric acid, nitric acid and acetic acid aqueous solution, preferably an aqueous solution of hydrochloric acid;

[0069] The concentration of the acid solution is 0.1–12 mol / L, preferably 0.1–1 mol / L.

[0070] In this invention, the preparation method first uses a hydrothermal method to prepare a mesoporous silica filter cake, then mixes the clay mineral components with the silica filter cake using a high-efficiency ball milling method, and obtains a highly dispersed spherical clay mesoporous composite material by centrifugal spray drying. Finally, the acid-modified clay mesoporous composite material is obtained through acid modification treatment.

[0071] A second aspect of the present invention provides a modified clay mesoporous composite catalyst prepared by the above-described preparation method.

[0072] In this invention, the catalyst uses spherical mesoporous silica as a matrix, and clay mineral components (active components) are supported on the matrix by a high-efficiency ball milling method. The modified clay mesoporous composite catalyst is obtained by acid treatment through impregnation.

[0073] According to the present invention, preferably, the modified clay mesoporous composite catalyst comprises at least one of the following characteristics:

[0074] The modified clay mesoporous composite catalyst has a spherical structure; the pore size is 2nm to 50nm, preferably 20nm to 30nm; and the specific surface area is 25m². 2 g -1 ~1200m 2 g -1 The preferred size is 200m 2 g -1 ~350m 2 g -1 The clay content is 1 wt% to 40 wt% of the total mass of the catalyst, preferably 10 wt% to 36 wt%.

[0075] A third aspect of the present invention provides the application of the above-described modified clay mesoporous composite catalyst as a catalyst for the preparation of isopropyl ether by the isopropanol dehydration method.

[0076] The present invention is further illustrated by the following examples:

[0077] The P123 used in the following examples and comparative examples was purchased from BASF; the ethanol was anhydrous ethanol.

[0078] Example 1:

[0079] Step 1: Preparation of mesoporous silica filter cake:

[0080] 200g of P123 (triblock copolymer polyethylene oxide-polypropylene oxide-polyethylene oxide) and 338g of ethanol were added to 5600mL of a buffer solution of acetic acid and sodium acetate (pH=4.4). The mixture was stirred at 15°C until P123 was completely dissolved. Then, 1200g of trimethylpentane was added to the above solution and stirred at 15°C for 8 hours. After that, 426g of TEOS was added to the above solution and stirred at 15°C for 20 hours. The solution was then transferred to a polytetrafluoroethylene-lined reactor and crystallized in an oven at 150°C for 24 hours. After filtration and washing with ethanol at 120°C, a mesoporous silica filter cake with the template agent removed was obtained.

[0081] Step 2: Preparation of clay-mesoporous composite slurry:

[0082] 900g of the prepared mesoporous silica filter cake, 300g of sepiolite, and 2000mL of deionized water were placed in a 6000mL ball mill jar. Both the ball mill jar and the grinding balls were made of agate (silica purity exceeding 99%), with 40 grinding balls of 2mm diameter. The ball mill was operated at 400rpm. The jar was sealed, and the mixture was ball-milled at 60℃ for 20 hours to obtain a clay-mesoporous composite slurry (sepiolite-mesoporous composite slurry).

[0083] Step 3: Preparation of clay mesoporous composite materials:

[0084] The sepiolite mesoporous composite slurry was diluted with deionized water to a solids concentration of 30 wt% (based on the total weight of the material used for centrifugal spray drying), and then centrifugally spray-dried in an atomizer to obtain the sepiolite mesoporous composite material. The spray drying inlet temperature was 200℃, the outlet temperature was 100℃, and the atomizer speed was 8000 rpm.

[0085] Step 4: Preparation of acid-modified clay mesoporous composite material:

[0086] The 50g of sepiolite mesoporous composite material prepared above was mixed with 0.2mol / L hydrochloric acid aqueous solution at a solid-liquid ratio of 1:15g / mL. The mixture was stirred in an oil bath at 70℃ for 10h. After removal, it was washed with deionized water until the filtrate was neutral and dried at 110℃ for 6h to obtain the acid-modified clay mesoporous composite material catalyst.

[0087] Example 2:

[0088] Step 1: Preparation of mesoporous silica filter cake:

[0089] 200g of P123 and 338g of ethanol were added to 5600mL of a buffer solution of acetic acid and sodium acetate (pH=4.4). The mixture was stirred at 15°C until P123 was completely dissolved. Then, 1200g of trimethylpentane was added to the above solution and stirred at 15°C for 8 hours. After that, 426g of TEOS was added to the above solution and stirred at 15°C for 20 hours. The solution was then transferred to a polytetrafluoroethylene-lined reactor and crystallized in an oven at 150°C for 24 hours. After filtration and washing with ethanol at 120°C, a mesoporous silica filter cake with the template agent removed was obtained.

[0090] Step 2: Preparation of clay-mesoporous composite slurry:

[0091] 900g of the prepared mesoporous silica filter cake, 300g of sepiolite, and 2000mL of deionized water were placed in a 6000mL ball mill jar. Both the ball mill jar and the grinding balls were made of agate (silica purity exceeding 99%), with 40 grinding balls of 2mm diameter. The ball mill was operated at 400rpm. The jar was sealed, and the mixture was ball-milled at 60℃ for 20 hours to obtain a clay-mesoporous composite slurry (sepiolite-mesoporous composite slurry).

[0092] Step 3: Preparation of clay mesoporous composite materials:

[0093] The sepiolite mesoporous composite slurry was diluted with deionized water to a solids concentration of 30 wt% (based on the total weight of the material used for centrifugal spray drying), and then centrifugally spray-dried in an atomizer to obtain the sepiolite mesoporous composite material. The spray drying inlet temperature was 200℃, the outlet temperature was 100℃, and the atomizer speed was 8000 rpm.

[0094] Step 4: Preparation of acid-modified clay mesoporous composite material:

[0095] The 50g of sepiolite mesoporous composite material prepared above was mixed with 0.2mol / L sulfuric acid aqueous solution at a solid-liquid ratio of 1:15g / mL. The mixture was stirred in an oil bath at 70℃ for 10h. After removal, it was washed with deionized water until the filtrate was neutral and dried at 110℃ for 6h to obtain the acid-modified clay mesoporous composite material catalyst.

[0096] Example 3:

[0097] Step 1: Preparation of mesoporous silica filter cake:

[0098] 200g of P123 and 338g of ethanol were added to 5600mL of a buffer solution of acetic acid and sodium acetate (pH=4.4). The mixture was stirred at 15°C until P123 was completely dissolved. Then, 1200g of trimethylpentane was added to the above solution and stirred at 15°C for 8 hours. After that, 426g of TEOS was added to the above solution and stirred at 15°C for 20 hours. The solution was then transferred to a polytetrafluoroethylene-lined reactor and crystallized at 150°C for 24 hours in an oven. After filtration and washing with ethanol at 120°C, a mesoporous silica filter cake with the template agent removed was obtained.

[0099] Step 2: Preparation of clay-mesoporous composite slurry:

[0100] 900g of the prepared mesoporous silica filter cake, 300g of sepiolite, and 2000mL of deionized water were placed in a 6000mL ball mill jar. Both the ball mill jar and the grinding balls were made of agate (silica purity exceeding 99%), with 40 grinding balls of 2mm diameter. The ball mill was operated at 400rpm. The jar was sealed, and the mixture was ball-milled at 60℃ for 20 hours to obtain a clay-mesoporous composite slurry (sepiolite-mesoporous composite slurry).

[0101] Step 3: Preparation of clay mesoporous composite materials:

[0102] The sepiolite mesoporous composite slurry was diluted with deionized water to a solids concentration of 30 wt% (based on the total weight of the material used for centrifugal spray drying), and then centrifugally spray-dried in an atomizer to obtain the sepiolite mesoporous composite material. The spray drying inlet temperature was 200℃, the outlet temperature was 100℃, and the atomizer speed was 8000 rpm.

[0103] Step 4: Preparation of acid-modified clay mesoporous composite material:

[0104] The 50g of sepiolite mesoporous composite material prepared above was mixed with 0.2mol / L nitric acid aqueous solution at a solid-liquid ratio of 1:15g / mL. The mixture was stirred in an oil bath at 70℃ for 10h. After removal, it was washed with deionized water until the filtrate was neutral and dried at 110℃ for 6h to obtain the acid-modified clay mesoporous composite material catalyst.

[0105] Example 4:

[0106] Step 1: Preparation of mesoporous silica filter cake:

[0107] 200g of P123 and 338g of ethanol were added to 5600mL of a buffer solution of acetic acid and sodium acetate (pH=4.4). The mixture was stirred at 15°C until P123 was completely dissolved. Then, 1200g of trimethylpentane was added to the above solution. After stirring at 15°C for 8 hours, 426g of TEOS was added to the above solution. After stirring at 15°C for 20 hours, the solution was transferred to a polytetrafluoroethylene-lined reactor and crystallized at 100°C for 24 hours in an oven. After filtration and washing with ethanol at 120°C, a mesoporous silica filter cake with the template agent removed was obtained.

[0108] Step 2: Preparation of clay-mesoporous composite slurry:

[0109] 900g of the prepared mesoporous silica filter cake, 300g of illite, and 2000mL of deionized water were placed in a 6000mL ball mill jar. Both the ball mill jar and the grinding balls were made of agate (silica purity exceeding 99%), with 40 grinding balls of 2mm diameter. The ball mill was operated at 400rpm. The jar was sealed, and the mixture was ball-milled at 60℃ for 20 hours to obtain a clay-mesoporous composite slurry (illite-mesoporous composite slurry).

[0110] Step 3: Preparation of clay mesoporous composite materials:

[0111] The illite mesoporous composite slurry was diluted with deionized water to a solids concentration of 30 wt% (based on the total weight of the material used for centrifugal spray drying), and then centrifugally spray-dried in an atomizer to obtain the illite mesoporous composite material. The spray drying inlet temperature was 200℃, the outlet temperature was 100℃, and the atomizer speed was 8000 rpm.

[0112] Step 4: Preparation of acid-modified clay mesoporous composite material:

[0113] The 50g illite mesoporous composite material prepared above was mixed with 0.2mol / L hydrochloric acid aqueous solution at a solid-liquid ratio of 1:15g / mL. The mixture was stirred in an oil bath at 70℃ for 10h. After removal, it was washed with deionized water until the filtrate was neutral and dried at 110℃ for 6h to obtain the acid-modified clay mesoporous composite material catalyst.

[0114] Comparative Example 1:

[0115] The only difference between this comparative example and Example 1 is the removal of acid modification step four, resulting in an unacidified sepiolite mesoporous composite catalyst.

[0116] Comparative Example 2

[0117] The only difference between this comparative example and Example 4 is the removal of acid modification step four, resulting in an unacidified illite mesoporous composite catalyst.

[0118] Comparative Example 3

[0119] Comparative Example 3 is an acid-modified, uncomposite mesoporous silica material.

[0120] Step 1: Preparation of mesoporous silica filter cake:

[0121] 200g of P123 and 338g of ethanol were added to 5600mL of a buffer solution of acetic acid and sodium acetate (pH=4.4). The mixture was stirred at 15°C until P123 was completely dissolved. Then, 1200g of trimethylpentane was added to the above solution and stirred at 15°C for 8 hours. After that, 426g of TEOS was added to the above solution and stirred at 15°C for 20 hours. The solution was then transferred to a polytetrafluoroethylene-lined reactor and crystallized in an oven at 150°C for 24 hours. After filtration and washing with ethanol at 120°C, a mesoporous silica filter cake with the template agent removed was obtained.

[0122] Step 2: Preparation of mesoporous silica slurry:

[0123] 1200g of the prepared mesoporous silica filter cake and 2000mL of deionized water were placed in a 6000mL ball mill jar. Both the ball mill jar and the grinding balls were made of agate (silica purity exceeding 99%), with 40 grinding balls of 2mm diameter. The ball mill was operated at 400rpm. The jar was sealed, and the mixture was ball-milled at 60℃ for 20 hours to obtain a mesoporous silica slurry.

[0124] Step 3: Preparation of spherical mesoporous silica material:

[0125] Mesoporous silica slurry was diluted with deionized water to a solids concentration of 30 wt% (based on the total weight of the material used for centrifugal spray drying), and then centrifugally spray-dried in an atomizer to obtain spherical mesoporous silica material. The spray drying inlet temperature was 200℃, the outlet temperature was 100℃, and the atomizer speed was 12000 rpm.

[0126] Step 4: Preparation of acid-modified clay mesoporous composite material:

[0127] The 50g spherical mesoporous silica material prepared above was mixed with 0.2mol / L hydrochloric acid aqueous solution at a solid-liquid ratio of 1:15g / mL. The mixture was stirred in an oil bath at 70℃ for 10h. After removal, it was washed with deionized water until the filtrate was neutral. The mixture was then dried at 110℃ for 6h to obtain acid-modified uncomposite mesoporous silica material.

[0128] Test Example 1

[0129] The catalysts prepared in the above examples and comparative examples were subjected to X-ray diffraction, and the test results are as follows.

[0130] Figure 1 The X-ray powder diffraction pattern of the acid-modified clay mesoporous composite material in Example 1 shows three diffraction peaks between 0.5° and 2°, corresponding to the (100), (110), and (200) plane diffraction peaks, respectively, indicating that the clay mesoporous composite material has a two-dimensional hexagonal (p6mm) structure. Among them, the (100) plane diffraction peak has high intensity and narrow peak shape, indicating that it has a regular long-range ordered structure.

[0131] Figure 9 The X-ray powder diffraction pattern of the acid-modified clay mesoporous composite material in Example 2 shows three diffraction peaks between 0.5° and 2° 2θ, corresponding to the diffraction peaks of the (100), (110), and (200) planes, respectively, indicating that the clay mesoporous composite material has a two-dimensional hexagonal (p6mm) structure. Among them, the diffraction peak of the (100) plane has high intensity and narrow peak shape, indicating that it has a regular long-range ordered structure.

[0132] Figure 15 The X-ray powder diffraction pattern of the unmodified clay mesoporous composite material in Comparative Example 1 shows three diffraction peaks between 0.5° and 2° 2θ, corresponding to the (100), (110), and (200) plane diffraction peaks, indicating that the clay mesoporous composite material has a two-dimensional hexagonal (p6mm) structure. Among them, the (100) plane diffraction peak has high intensity and narrow peak shape, indicating that it has a regular long-range ordered structure. Compared with the acid-modified clay mesoporous composite material, the peak shape of its X-ray powder diffraction pattern did not change significantly, proving that the acid modification process does not destroy the main structure of the material. The peak intensity decreased slightly after acid modification, which may be due to the decrease in the degree of crystallinity of the material caused by defects introduced during the modification process.

[0133] X-ray diffraction results of Examples 3, 4 and Comparative Example 2 show that the obtained materials have a two-dimensional hexagonal (p6mm) structure.

[0134] Test Example 2

[0135] The specific surface area, pore size, and pore volume of the catalysts prepared in the above examples and comparative examples were tested. Specific test results are shown in Table 1 and... Figure 2 , 3 10, 11, 16, and 17; among them, the specific surface area was determined by nitrogen adsorption method; the pore size and pore volume were calculated based on non-local density functional theory (NLDFT) combined with columnar pore model.

[0136] Table 1

[0137] sample <![CDATA[Specific surface area (m 2 / g)]]> Aperture (nm) Quantity (cc / g) Example 1 282 24.2 1.2 Example 2 275 24.0 1.0 Example 3 272 24.5 0.9 Example 4 255 7.6 1.0 Comparative Example 1 260 25.0 1.0 Comparative Example 2 262 7.8 0.8 Comparative Example 3 308 15.2 1.2

[0138] Figure 2 The nitrogen adsorption-desorption curve of the acid-modified clay mesoporous composite catalyst prepared in Example 1 shows that the obtained material has a mesoporous structure and a specific surface area of ​​282 m². 2 g -1 This indicates that the acid-modified clay mesoporous composite catalyst has a uniform and well-developed pore structure. Figure 3 The pore size distribution curve of the acid-modified clay mesoporous composite catalyst prepared in Example 1 shows that the pore size distribution of the obtained material is concentrated at 24.2 nm.

[0139] Figure 10 The nitrogen adsorption-desorption curve of the acid-modified clay mesoporous composite catalyst prepared in Example 2 shows that the obtained material has a mesoporous structure and a specific surface area of ​​273 m². 2 g -1 This indicates that the acid-modified clay mesoporous composite catalyst has a uniform and well-developed pore structure. Figure 11 The pore size distribution curve of the acid-modified clay mesoporous composite catalyst prepared in Example 2 shows that the pore size distribution of the obtained material is concentrated at 24.0 nm.

[0140] Figure 16 The nitrogen adsorption-desorption curves of the unmodified clay mesoporous composite catalyst prepared in Comparative Example 1 show that the obtained material has a mesoporous structure and a specific surface area of ​​260 m². 2 g -1 This indicates that the spherical clay mesoporous composite catalyst has a uniform and well-developed pore structure. Figure 17 The pore size distribution curve of the unmodified clay mesoporous composite catalyst prepared for Comparative Example 1 shows that the pore size distribution of the obtained material is concentrated at 25.0 nm. The slight decrease in pore size after acid modification may be due to the steric hindrance generated in the pores by the introduction of oxygen-containing functional groups.

[0141] Test Example 3

[0142] Scanning electron microscopy was performed on the catalysts prepared in the above examples and comparative examples. Specific results are shown in [link to results]. Figure 4 .

[0143] Figure 4 The scanning electron microscope image of the acid-modified clay mesoporous composite catalyst prepared in Example 1 shows that the obtained material consists of spherical particles, and the acidification process did not cause them to break down.

[0144] Test Example 4

[0145] The catalysts prepared in the above examples and comparative examples were subjected to ammonia-programmed temperature desorption tests. Specific test results are shown in [link to results]. Figure 5 ,12 18.

[0146] Figure 5 The ammonia-programmed temperature desorption curve of the acid-modified clay mesoporous composite catalyst prepared in Example 1 shows that the surface of the obtained material is acidic.

[0147] Figure 12 The ammonia-programmed temperature desorption curve of the acid-modified clay mesoporous composite catalyst prepared in Example 2 shows that the surface of the obtained material is acidic.

[0148] Figure 18 The ammonia-programmed temperature desorption curve of the unmodified clay mesoporous composite catalyst prepared in Comparative Example 1 shows that the surface of the acid-modified clay mesoporous composite material has weak acidity.

[0149] Test Example 5

[0150] The catalysts prepared in the above examples and comparative examples were subjected to X-ray photoelectron spectroscopy and scanning electron microscopy, and the specific test results are as follows.

[0151] X-ray photoelectron spectroscopy and scanning electron microscopy revealed the presence of O, Si, and Mg on the surface of the catalysts prepared in Examples 1-3 and Comparative Example 1, indicating that sepiolite was successfully combined with mesoporous materials.

[0152] X-ray photoelectron spectroscopy and scanning electron microscopy revealed the presence of O, Si, and Mg on the surface of the catalysts prepared in Example 4 and Comparative Example 2, indicating that illite was successfully combined with mesoporous materials.

[0153] X-ray photoelectron spectroscopy and scanning electron microscopy revealed the presence of O and Si on the surface of the catalyst prepared in Comparative Example 2.

[0154] Test Example 6

[0155] (1) The catalytic performance of the catalysts prepared in the above examples and comparative examples was evaluated. The specific test results are shown in Table 2, Table 3 and the figure below. The specific test methods are as follows.

[0156] The catalytic activity of the catalyst was evaluated using a quick-opening magnetically driven reactor. In each reaction, 500 mg of catalyst and 30 mL of isopropanol were used. The mixture was heated at 190 °C for 4 h with magnetic stirring at 400 rpm. After the reaction, the mixture was cooled in an ice-water bath for 30 min. The amount of propylene byproduct was analyzed by headspace gas chromatography, and the liquid product was quantified by NMR. For each reaction, 300 μL of the liquid was taken, and 100 μL of deuterated chloroform and 1 μmol of dimethyl sulfoxide (DMSO) were added as an external standard. The isopropanol conversion and isopropyl ether selectivity were calculated using the following formulas.

[0157]

[0158] Where: X IPA Isopropanol conversion rate (%); S IPE Selectivity for isopropyl ether (%); n IPA n represents the amount of isopropanol in the product after the reaction. IPE n represents the amount of isopropyl ether in the product after the reaction. P This represents the amount of propylene in the product after the reaction.

[0159] After each round of reaction was completed and samples were taken, the reaction suspension was centrifuged at 10,000 rpm for 3 min and then dried at 60 °C for 2 h to collect the catalyst powder. Long-cycle testing was then conducted according to the above-mentioned catalytic activity evaluation method.

[0160] Table 2

[0161] sample Isopropanol conversion rate (%) Isopropyl ether selectivity (%) Example 1 48.15 93.65 Example 2 46.76 86.61 Example 3 46.18 87.13 Example 4 45.12 85.38 Comparative Example 1 37.46 76.20 Comparative Example 2 35.68 78.14 Comparative Example 3 0 0

[0162] As shown in Table 2, compared with Comparative Examples 1-2, the catalyst of the present invention, after acid modification, can effectively improve the catalytic activity of the clay mesoporous composite material; in Comparative Example 3, the acid-modified uncomposite mesoporous silica material was tested and no product was detected, indicating that the uncomposite mesoporous silica material does not have isopropanol dehydration activity even after acid modification.

[0163] Figure 6 The image shows the NMR spectrum of the liquid-phase product after catalysis by the acid-modified clay mesoporous composite catalyst prepared in Example 1. Figure 7 The image shows the gas phase chromatogram of the product after catalysis by the acid-modified clay mesoporous composite catalyst prepared in Example 1. Based on the above formula, the isopropanol conversion and isopropyl ether selectivity of the acid-modified clay mesoporous composite catalyst prepared in Example 1 were calculated to be 48.15% and 93.65%, respectively.

[0164] Figure 13 The image shows the NMR spectrum of the liquid-phase product after catalysis by the acid-modified clay mesoporous composite catalyst prepared in Example 2. Figure 14 The image shows the gas phase chromatogram of the product after catalysis by the acid-modified clay mesoporous composite catalyst prepared in Example 2. Based on the above formula, the isopropanol conversion and isopropyl ether selectivity of the acid-modified clay mesoporous composite catalyst prepared in Example 2 were calculated to be 46.76% and 86.61%, respectively.

[0165] Figure 19 The NMR spectrum of the liquid-phase product after catalysis by the unmodified clay mesoporous composite catalyst prepared in Comparative Example 1 is shown. Figure 20The chromatogram of the gas phase product after catalysis by the unmodified clay mesoporous composite catalyst prepared for Comparative Example 1 is shown. Based on the above formula, the isopropanol conversion and isopropyl ether selectivity of the unmodified clay mesoporous composite catalyst prepared for Comparative Example 1 were calculated to be 37.46% and 76.21%, respectively.

[0166] Table 3

[0167] sample Service life (h) Example 1 ≥24 Example 2 ≥24 Example 3 ≥24 Example 4 ≥24 Comparative Example 1 ≥24 Comparative Example 2 ≥24

[0168] As shown in Table 3, the catalysts prepared in Examples 1-4 and Comparative Examples 1-2 have strong long-cycle stability. After 6 cycles (24 h), the isopropanol conversion and isopropyl ether selectivity did not show significant decline, indicating that the acidification process does not affect the stability of the catalyst.

[0169] Figure 8 The figure shows the isopropanol dehydration stability test of the acid-modified clay mesoporous composite catalyst prepared in Example 1. It indicates that the obtained material has strong long-term cycling stability; after 6 cycles (24 h), neither the isopropanol conversion nor the isopropyl ether selectivity showed significant decline.

[0170] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for preparing a modified clay mesoporous composite catalyst, characterized in that, The preparation method includes: (1) Crystallize the mesoporous silica precursor solution containing template agent, silicon source and pore expander to obtain mesoporous silica filter cake. (2) The mesoporous silica filter cake, clay minerals and the first dispersant are mixed to obtain a clay mesoporous composite slurry; then the clay mesoporous composite slurry is optionally diluted and dried to obtain a clay mesoporous composite material. (3) The clay mesoporous composite material is mixed with an acid solution to obtain a modified clay mesoporous composite material catalyst.

2. The preparation method according to claim 1, wherein, The mesoporous silica precursor solution containing a template agent, a silicon source, and a pore-expanding agent is prepared by a method comprising the following steps: mixing the template agent, the silicon source, the pore-expanding agent, and the second dispersant uniformly to obtain the mesoporous silica precursor solution; The second dispersant comprises a buffer solution of acetic acid and sodium acetate with ethanol.

3. The preparation method according to claim 1, wherein, In step (1), the template agent is a triblock copolymer of polyethylene oxide-propylene oxide-ethylene oxide; The silicon source is tetraethyl orthosilicate; The pore-expanding agent is 3-methylpentane; The crystallization temperature is 80℃~300℃, and the time is 12h~36h; Preferably, the crystallization temperature is 100℃~150℃ and the time is 20h~24h.

4. The preparation method according to claim 1, wherein, In step (2), the clay mineral is at least one of sepiolite, illite, attapulgite and zeolite; preferably sepiolite and / or illite.

5. The preparation method according to claim 1, wherein, In step (2), the mixing is ball milling mixing; The mixing temperature is 15℃~80℃, and the time is 1h~100h; preferably, the mixing temperature is 60℃~70℃, and the time is 20~24h. The first dispersant is water; The mass ratio of the clay mineral to the mesoporous silica filter cake is (1-5):9; In the clay-mesoporous composite slurry, the sum of the amounts of the mesoporous silica filter cake and clay minerals per liter of the first dispersant is 0.5 kg to 1.5 kg, preferably 0.5 kg to 1 kg.

6. The preparation method according to claim 1, wherein, In step (2), the drying is spray drying, preferably centrifugal spray drying; The inlet temperature of the spray dryer is 150℃~200℃, and the outlet temperature is 90~120℃; The concentration of solids in the material used for drying is 10–50 wt%. The spray drying is carried out in an atomizer with a rotation speed of 8000 rpm to 16000 rpm.

7. The preparation method according to claim 1, wherein, In step (3), the solid-liquid ratio of the clay mesoporous composite material to the acid solution is 1:(2-30)g / mL, preferably 1:(10-20)g / mL; The mixing temperature is 25–100°C, and the time is 0.5–36 h; Preferably, the mixing temperature is 60–80°C and the mixing time is 8–10 hours; Preferably, after mixing the clay mesoporous composite material with the acid solution, it is further washed and dried, and the drying temperature is 50-200℃, preferably 100-120℃.

8. The preparation method according to claim 1, wherein, In step (3), the acid solution is at least one of hydrochloric acid, sulfuric acid, nitric acid and acetic acid aqueous solution, preferably an aqueous solution of hydrochloric acid; The concentration of the acid solution is 0.1–12 mol / L, preferably 0.1–1 mol / L.

9. A modified clay mesoporous composite catalyst prepared by the preparation method according to any one of claims 1-8.

10. The modified clay mesoporous composite catalyst according to claim 9, wherein, The modified clay mesoporous composite catalyst includes at least one of the following characteristics: The modified clay mesoporous composite catalyst has a spherical structure; the pore size is 2nm to 50nm, preferably 20nm to 30nm; and the specific surface area is 25m². 2 g -1 ~1200m 2 g -1 The preferred size is 200m 2 g -1 ~350m 2 g -1 The clay content is 1 wt% to 40 wt% of the total mass of the catalyst, preferably 10 wt% to 36 wt%.

11. The application of the modified clay mesoporous composite catalyst according to claim 9 or 10 as a catalyst for the preparation of isopropyl ether by the isopropanol dehydration method.

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