Preparation method of novel MCM-41 catalyst

Abstract

A method for preparing a novel MCM-41 catalyst includes mixing TEOS, CTAB, a metal compound, sulfonated tripropylene glycol methyl ether, sodium hydroxide, and water to obtain a raw material solution containing a microcellular template. The amount of TEOS is 1 mole, the amount of the metal oxide is 0.03 to 0.1 moles, the amount of CTAB is 1 mole, and the amount of sulfonated tripropylene glycol methyl ether is 0.1 to 0.3 moles. The pH of the raw material solution is adjusted to precipitate the metal hydroxide, obtaining a colloidal solution. The colloidal solution is heated to hydrolyze the TEOS, and the hydrolyzed TEOS and metal hydroxide self-assemble and coat the microcellular template to form a catalyst precursor. The catalyst precursor is washed, dried, and calcined to obtain the novel MCM-41 catalyst. The novel MCM-41 catalyst prepared by the method of this invention can further improve the yield of secondary alcohol products.

Description

Technical Field

[0001] This invention relates to a catalyst, and more particularly to a method for preparing a novel MCM-41 catalyst. Prior Technology

[0002] MCM-41 catalyst is a catalyst with a pure silicon oxide backbone formed by using microcells formed by tetraethoxysilane with surfactants such as hexadecyltrimethylammonium bromide as templates.

[0003] However, when the MCM-41 catalyst prepared using existing methods is used to produce secondary alcohol products such as propylene glycol monomethyl ether, it suffers from the problem of incomplete secondary alcohol production, resulting in the presence of some primary alcohol byproducts. Therefore, developing new methods for preparing MCM-41 catalysts, thereby maximizing the yield of secondary alcohol products when used in the production of products like propylene glycol monomethyl ether, is a direction that the industry currently needs to focus on. Summary of the Invention

[0004] Therefore, the object of the present invention is to provide a method for preparing a novel MCM-41 catalyst that can produce a catalyst that can improve the yield of secondary alcohol products.

[0005] Therefore, the preparation method of the novel MCM-41 catalyst of the present invention includes steps (a), (b), (c), (d), (e), and (f).

[0006] Step (a) involves mixing tetraethoxysilane, hexadecyltrimethylammonium bromide, a metal compound, sulfonated tripropylene glycol methyl ether, sodium hydroxide, and water, and then using the hexadecyltrimethylammonium bromide and the sulfonated tripropylene glycol methyl ether to form a micro-cell template, thereby obtaining a raw material solution containing the micro-cell template. The amount of tetraethoxysilane used is 1 mol, the amount of the metal oxide ranges from 0.03 mol to 0.1 mol, and the amount of the sulfonated tripropylene glycol methyl ether ranges from 0.1 mol to 0.3 mol, based on 1 mol of hexadecyltrimethylammonium bromide.

[0007] Step (b) involves adjusting the pH of the raw material solution to 9.5 to 10.5 so that the metal compound is converted into a metal hydroxide and precipitated from the raw material solution, thereby obtaining a colloidal solution containing the microcell template and the metal hydroxide.

[0008] Step (c) involves heating the colloidal solution to hydrolyze the tetraethoxysilane to form an ethoxylated silicon hydroxide, and then allowing the ethoxylated silicon hydroxide to self-assemble with the metal hydroxide and coat the microcellular template to form a catalyst precursor.

[0009] Step (d) involves washing the catalyst precursor with water until the pH of the resulting liquid is between 7.0 and 7.5, thus obtaining a washed catalyst precursor.

[0010] Step (e) involves drying the water-washed catalyst precursor to obtain a dried catalyst precursor.

[0011] Step (f) involves calcining the dried catalyst precursor at 300°C to 500°C to remove the organic matter containing the microcellular template from the catalyst precursor, thereby obtaining a novel MCM-41 catalyst.

[0012] The advantages of this invention are: by adding the metal compound and the sulfonated tripropylene glycol methyl ether, and controlling the relative amounts of the metal compound and the tetraethoxysilane, and controlling the relative amounts of the sulfonated tripropylene glycol methyl ether and the hexadecyltrimethylammonium bromide, the novel MCM-41 catalyst prepared by this method can further improve the yield of secondary alcohol products. Implementation

[0013] The present invention provides a method for preparing a novel MCM-41 catalyst, comprising steps (a), (b), (c), (d), (e), and (f).

[0014] Step (a) involves mixing tetraethoxysilane, hexadecyltrimethylammonium bromide, a metal compound, sulfonated tripropylene glycol methyl ether, sodium hydroxide, and water, and then using the hexadecyltrimethylammonium bromide and the sulfonated tripropylene glycol methyl ether to form a micro-cell template, thereby obtaining a raw material solution containing the micro-cell template. The amount of tetraethoxysilane used is 1 mol, the amount of the metal oxide ranges from 0.03 mol to 0.1 mol, and the amount of the sulfonated tripropylene glycol methyl ether ranges from 0.1 mol to 0.3 mol, based on 1 mol of hexadecyltrimethylammonium bromide.

[0015] Step (b) involves adjusting the pH of the raw material solution to 9.5 to 10.5 so that the metal compound is converted into a metal hydroxide and precipitated from the raw material solution, thereby obtaining a colloidal solution containing the microcell template and the metal hydroxide.

[0016] Step (c) involves heating the colloidal solution to hydrolyze the tetraethoxysilane to form an ethoxylated silicon hydroxide, and then allowing the ethoxylated silicon hydroxide to self-assemble with the metal hydroxide and coat the microcellular template to form a catalyst precursor.

[0017] Step (d) involves washing the catalyst precursor with water until the pH of the resulting liquid is between 7.0 and 7.5, thus obtaining a washed catalyst precursor.

[0018] Step (e) involves drying the water-washed catalyst precursor to obtain a dried catalyst precursor.

[0019] Step (f) involves calcining the dried catalyst precursor at 300°C to 500°C to remove the organic matter containing the microcellular template from the catalyst precursor, thereby obtaining a novel MCM-41 catalyst.

[0020] In step (a), the hexadecyltrimethylammonium bromide and the sulfonated tripropylene glycol methyl ether are used as surfactants, and thus together they form the microcell template, which is used for the tetraethoxysilane to self-assemble according to the shape of the microcell template. The shape of the microcell template is, for example, but not limited to, columnar.

[0021] In this invention, by adding the sulfonated tripropylene glycol methyl ether, the pore size and specific surface area of ​​the prepared novel MCM-41 catalyst can be adjusted, thereby improving the selectivity for secondary alcohol products and reducing the formation of primary alcohol byproducts. The sulfonated tripropylene glycol methyl ether is a compound as shown in formula (A). Formula (A)

[0022] In some embodiments of the present invention, the sulfonated tripropylene glycol methyl ether is prepared by reacting tripropylene glycol methyl ether with chlorosulfonic acid, wherein the amount of tripropylene glycol methyl ether used ranges from 1 mole to 1.2 moles, based on 1 mole of chlorosulfonic acid. In some specific examples of the present invention, the sulfonated tripropylene glycol methyl ether is prepared by mixing tripropylene glycol methyl ether with chlorosulfonic acid under reduced pressure and reacting at 100°C for 24 hours to obtain a crude product. Then, the crude product is heated to distill off the remaining tripropylene glycol methyl ether, obtaining sulfonated tripropylene glycol methyl ether with a yield of 98% or higher.

[0023] In this invention, the metal compound is used to alter the microstructure of the pure silicon oxide framework formed by the self-assembly of ethoxylated silicon hydroxides derived from the hydrolysis of tetraethoxysilane, resulting in a composite framework with a structure different from that of pure silicon oxide. This enhances the structural integrity of the novel MCM-41 catalyst and reduces the formation of primary alcohol byproducts. Furthermore, the metal compound can adjust the pH value of the novel MCM-41 catalyst itself according to the application, thereby preparing a catalyst suitable for the reaction and facilitating the catalytic reaction. There are no particular limitations on the type of metal compound; any type capable of achieving the aforementioned effects is applicable to this invention. In some embodiments of this invention, the metal compound is selected from at least one of organic compounds of titanium, inorganic compounds of titanium, organic compounds of magnesium, inorganic compounds of magnesium, organic compounds of aluminum, and inorganic compounds of aluminum. In some embodiments of this invention, the metal compound is selected from aluminum isopropoxide and titanium isopropoxide.

[0024] In this invention, by controlling the amount of the metal compound to be between 0.03 mol and 0.1 mol, the selectivity of the novel MCM-41 catalyst for secondary alcohol products can be increased. Furthermore, by controlling the amount of the sulfonated tripropylene glycol methyl ether to be between 0.1 mol and 0.3 mol, the pore size of the novel MCM-41 catalyst can be controlled to an appropriate size, thereby facilitating the acquisition of secondary alcohol products.

[0025] In some embodiments of the present invention, based on 1 mole of tetraethoxysilane, the amount of hexadecyltrimethylammonium bromide is 0.9 to 1.3 moles, the amount of sodium hydroxide is 0.24 to 0.3 moles, and the amount of water is 100 to 120 moles. The use of hexadecyltrimethylammonium bromide at 0.9 moles or more further enables the formation of uniformly sized pores in the microcellular template; the use of hexadecyltrimethylammonium bromide at 1.3 moles or less further avoids the formation of pores of uneven size in the microcellular template and also facilitates subsequent removal of the microcellular template.

[0026] In step (b), adjusting the pH of the raw material solution is to enable the metal compound to transform into a metal hydroxide and precipitate. This allows the metal element in the metal hydroxide to replace some of the silicon elements in the pure silicon oxide framework formed by the ethoxylated silicon hydroxide obtained from the hydrolysis of tetraethoxysilane, thereby altering the microstructure and creating the composite framework. There are no particular limitations on the method of adjusting the pH of the raw material solution; any method that adjusts the pH to 9.5 to 10.5 is applicable to this invention, such as, but not limited to, using acidic reagents. In some embodiments of this invention, step (b) involves adjusting the pH of the raw material solution with concentrated hydrochloric acid.

[0027] In step (c), the temperature of the heat treatment is not particularly limited. Any temperature condition suitable for hydrolyzing the tetraethoxysilane to form an ethoxylated silicon hydroxide, and for allowing the ethoxylated silicon hydroxide to self-assemble with the metal hydroxide to form a composite framework coating the microcellular template, is applicable to this invention. In some embodiments of this invention, the temperature range for the heat treatment is 80°C to 100°C.

[0028] In step (d), the catalyst precursor is washed with water to remove residual salts on the catalyst precursor, thereby preventing the salts from absorbing water and affecting the surface catalytic activity of the novel MCM-41 catalyst.

[0029] In step (f), in addition to containing the microcellular template, in some embodiments of the present invention, when the type of metal compound contains an organometallic compound, the organic matter also contains substances derived from the organometallic compound.

[0030] The present invention will be further described with reference to the following embodiments, but it should be understood that the embodiments are for illustrative purposes only and should not be construed as limiting the implementation of the present invention.

[0031] [Preparation Example 1] Sulfonated tripropylene glycol methyl ether

[0032] Tripropylene glycol methyl ether was mixed with chlorosulfonic acid under reduced pressure and reacted at 100°C for 24 hours to obtain a crude product. The crude product was then heated to distill off any remaining tripropylene glycol methyl ether, yielding sulfonated tripropylene glycol methyl ether with a yield of over 98%. The amount of tripropylene glycol methyl ether used ranged from 1 mol to 1.2 mol, based on 1 mol of chlorosulfonic acid.

[0033] [Example 1]

[0034] One mole of tetraethoxysilane (TEOS), 1.1 mole of hexadecyltrimethylammonium bromide (CTAB), 0.1 mole of aluminum isopropoxide, 0.11 mole of sulfonated tripropylene glycol methyl ether (Sulfonated TPM) from Preparation Example 1, 0.27 mole of sodium hydroxide, and 110 mole of water were mixed and stirred for 24 hours to allow the hexadecyltrimethylammonium bromide and the sulfonated tripropylene glycol methyl ether to form a microcell template, thereby obtaining a raw material solution containing the microcell template. The amount of hexadecyltrimethylammonium bromide used was 1 mole, and the amount of sulfonated tripropylene glycol methyl ether used in Preparation Example 1 was 0.1 mole.

[0035] The pH of the raw material solution was adjusted to 9.5 to 10.5 using concentrated hydrochloric acid, so that the aluminum isopropoxide in the raw material solution was converted into solid aluminum hydroxide and precipitated from the raw material solution, thus obtaining a colloidal solution containing the tetraethoxysilane, the microcell template and the aluminum hydroxide.

[0036] A reflux device is set up and the colloidal solution is heated at 80°C to 100°C for 24 hours to hydrolyze the tetraethoxysilane to form ethoxylated silica hydroxide. The ethoxylated silica hydroxide in the colloidal solution then self-assembles with the aluminum hydroxide and coats the microcell template to form a composite framework, thereby forming a catalyst precursor containing the microcell template and the composite framework.

[0037] The catalyst precursor is placed in water for washing, and the catalyst precursor is separated from the washed liquid by centrifugation. The above steps are repeated multiple times until the pH value of the washed liquid is 7.0 to 7.5, thus obtaining a washed catalyst precursor.

[0038] The water-washed catalyst precursor is dried at 100°C to remove moisture, resulting in a dried catalyst precursor.

[0039] The dried catalyst precursor was calcined at 500°C to remove the organic matter containing the microcellular template, thus obtaining a novel MCM-41 catalyst.

[0040] [Examples 2 to 6 and Comparative Examples 1 to 5]

[0041] Examples 2 to 6 and Comparative Examples 1 to 5 were prepared in a manner similar to that of Example 1, with the difference being the change in the types and / or amounts of each component in the raw material solution and the calcination temperature, as shown in Tables 1 and 2. Specifically, Comparative Example 1 did not contain any metal compound, Comparative Examples 3 and 4 did not contain any sulfonated tripropylene glycol methyl ether, and Comparative Example 5 did not contain any metal compound or sulfonated tripropylene glycol methyl ether.

[0042] [Evaluation Items]

[0043] Pore ​​size and specific surface area of ​​MCM-41 catalyst: The pore size and specific surface area of ​​the novel MCM-41 catalyst in Example 1 were measured using a specific surface area and pore size analyzer (brand: Micromeritics; model: 3Flex 3500) and the gas adsorption method. The pore size and specific surface area of ​​the novel MCM-41 catalyst in Examples 2 to 6 and Comparative Examples 1 to 5 were measured using the same method. The results are shown in Tables 1 and 2.

[0044] Yield of secondary alcohol products: Propylene oxide, methanol, and the novel MCM-41 catalyst of Example 1 were mixed and reacted at 120°C to obtain an analyte containing propylene glycol monomethyl ether (i.e., the secondary alcohol product). The analyte was then analyzed using a gas chromatograph (Agilent; model: 7890A) to calculate the yield of propylene glycol monomethyl ether, thereby evaluating the effectiveness of the novel MCM-41 catalyst of Example 1 in the production of secondary alcohol products. The novel MCM-41 catalysts of Examples 2 to 6 and the MCM-41 catalysts of Comparative Examples 1 to 5 were analyzed using the same method. The results are shown in Tables 1 and 2.

[0045] Table 1 Example 1 2 3 4 5 6 TEOS (Moll) 1 1 1 1 1 1 CTAB (Moll) 1.1 1.1 1.1 1.1 1.1 1.1 Metal compounds type Aluminum isopropoxide Aluminum isopropoxide Aluminum isopropoxide Titanium isopropoxide Titanium isopropoxide Titanium isopropoxide Dosage (moles) 0.05 0.05 0.05 0.05 0.05 0.05 Sulfonated TPM (Mollium) 0.11 0.22 0.22 0.22 0.11 0.11 Sodium hydroxide (mol) 0.27 0.27 0.27 0.27 0.27 0.27 Water (Moll) 110 110 110 110 110 110 Drying temperature (°C) 100 100 100 100 100 100 Calcination temperature (°C) 500 500 300 500 500 300 MCM-41 Catalyst Hole size (nm) 2.8 2.7 2.7 2.7 2.8 2.8 Specific surface area (m² / g) 971.2 1014.2 998.2 989.3 965.4 958.7 Yield (%) of secondary alcohol products 91.8 92.1 91.7 91.9 91.2 91.0

[0046] Table 2 Comparative example 1 2 3 4 5 TEOS (Moll) 1 1 1 1 1 CTAB (Moll) 1.1 1.1 1.1 1.1 1.1 Metal compounds type No additions Aluminum isopropoxide Aluminum isopropoxide Titanium isopropoxide No additions Dosage (moles) 0 0.05 0.02 0.15 0 Sulfonated TPM (Mollium) 0.07 0.45 0 0 0 Sodium hydroxide (mol) 0.27 0.27 0.27 0.27 0.27 Water (Moll) 110 110 110 110 110 Drying temperature (°C) 100 100 100 100 100 Calcination temperature (°C) 300 300 300 300 500 MCM-41 Catalyst Hole size (nm) 2.9 2.7 2.9 2.9 2.9 Specific surface area (m² / g) 932.8 1012.3 922.3 928.7 932.8 Yield (%) of secondary alcohol products 90.5 90.9 90.1 90.2 90.8

[0047] Referring to Table 1, Examples 1 to 6 prepared MCM-41 catalysts by adding a metal compound and sulfonated tripropylene glycol methyl ether, with the amount of the metal compound controlled at 0.03 to 0.1 mol based on 1 mol of tetraethoxysilane, and the amount of the sulfonated tripropylene glycol methyl ether controlled at 0.1 to 0.3 mol based on 1 mol of hexadecyltrimethylammonium bromide. This enabled the novel MCM-41 catalysts prepared in Examples 1 to 6 to achieve a yield of over 91.0% when used in the production of secondary alcohol products.

[0048] In contrast, in Comparative Examples 1 to 5, Comparative Example 1 did not add a metal compound, and based on 1 mole of hexadecyltrimethylammonium bromide, the amount of sulfonated tripropylene glycol methyl ether was not controlled between 0.1 and 0.3 moles. Therefore, the yield of the MCM-41 catalyst prepared in Comparative Example 1 when used to produce secondary alcohol products was only 90.5% and less than 91.0%. Although Comparative Example 2 added a metal compound and sulfonated tripropylene glycol methyl ether, based on 1 mole of hexadecyltrimethylammonium bromide, Comparative Example 2 did not control the amount of sulfonated tripropylene glycol methyl ether to be between 0.1 and 0.3 moles. Therefore, the yield of the MCM-41 catalyst prepared in Comparative Example 2 when used to produce secondary alcohol products was less than 91.0%. The yield of the catalyst prepared in Comparative Examples 3 and 4 was only 90.9% to less than 91.0% when used to produce secondary alcohol products. In Comparative Examples 3 and 4, no sulfonated tripropylene glycol methyl ether was added, and the amount of metal compound was not controlled between 0.03 and 0.1 mol based on 1 mol of tetraethoxysilane. Therefore, the yield of the MCM-41 catalyst prepared in Comparative Examples 3 and 4 when used to produce secondary alcohol products was only 90.1% to 90.2% to less than 91.0%. In Comparative Example 5, no metal compound or sulfonated tripropylene glycol methyl ether was added, which is equivalent to the existing MCM-41 catalyst. Therefore, the yield of the MCM-41 catalyst prepared in Comparative Example 5 when used to produce secondary alcohol products was only 90.8% to less than 91.0%.

[0049] In summary, the method for preparing the novel MCM-41 catalyst of the present invention, by adding the metal compound and the sulfonated tripropylene glycol methyl ether, and controlling the relative amounts of the metal compound and the tetraethoxysilane, and the relative amounts of the sulfonated tripropylene glycol methyl ether and the hexadecyltrimethylammonium bromide, can further improve the yield of secondary alcohol products such as propylene glycol monomethyl ether, thus effectively achieving the objective of the present invention.

[0050] However, the above description is merely an embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the scope of the patent application and the contents of the patent specification of the present invention shall still fall within the scope of the patent of the present invention.

Claims

1. A method for preparing a novel MCM-41 catalyst, comprising: (a) mixing tetraethoxysilane, hexadecyltrimethylammonium bromide, a metal compound, sulfonated tripropylene glycol methyl ether, sodium hydroxide, and water, and allowing the hexadecyltrimethylammonium bromide and the sulfonated tripropylene glycol methyl ether to jointly form a microcell template, thereby obtaining a raw material solution containing the microcell template, wherein, (a) The amount of the metal oxide ranges from 0.03 mol to 0.1 mol, based on 1 mol of tetraethoxysilane; the amount of the sulfonated tripropylene glycol methyl ether ranges from 0.1 mol to 0.3 mol, based on 1 mol of hexadecyltrimethylammonium bromide; (b) The pH of the raw material solution is adjusted to 9.5 to 10.5 so that the metal compound is converted into a metal hydroxide and precipitated from the raw material solution to obtain a colloidal solution containing the microcell template and the metal hydroxide; (c) The colloidal solution is heated to hydrolyze the tetraethoxysilane to form an ethoxylated silica hydroxide, and the ethoxylated silica hydroxide self-assembles with the metal hydroxide and coats the microcell template to form a catalyst precursor, wherein the temperature range of the heating treatment is 80°C to 100°C; (d) The catalyst precursor is washed with water until the pH of the liquid obtained from the washing is 7.0 to 7.5 to obtain a washed catalyst precursor; (e) The washed catalyst precursor is dried to obtain a dried catalyst precursor; and (f) The dried catalyst precursor is calcined at 300°C to 500°C to remove the organic matter containing the microcellular template in the catalyst precursor to obtain a novel MCM-41 catalyst.

2. The method for preparing the novel MCM-41 catalyst as described in claim 1, wherein, Based on a dosage of 1 mole of tetraethoxysilane, the dosage of hexadecyltrimethylammonium bromide is 0.9 to 1.3 moles, the dosage of sodium hydroxide is 0.24 to 0.3 moles, and the dosage of water is 100 to 120 moles.

3. The method for preparing the novel MCM-41 catalyst as described in claim 1, wherein, The sulfonated tripropylene glycol methyl ether is a compound as shown in formula (A).

4. The method for preparing the novel MCM-41 catalyst as described in claim 3, wherein, The sulfonated tripropylene glycol methyl ether is prepared by reacting tripropylene glycol methyl ether with chlorosulfonic acid, wherein the amount of tripropylene glycol methyl ether ranges from 1 mol to 1.2 mol, based on the amount of chlorosulfonic acid being 1 mol.

5. The method for preparing the novel MCM-41 catalyst as described in claim 1, wherein, The metal compound is selected from at least one of the following: organic compounds of titanium, inorganic compounds of titanium, organic compounds of magnesium, inorganic compounds of magnesium, organic compounds of aluminum, and inorganic compounds of aluminum.

6. The method for preparing the novel MCM-41 catalyst as described in claim 5, wherein, The metal compound is selected from aluminum isopropoxide and titanium isopropoxide.

7. The method for preparing the novel MCM-41 catalyst as described in claim 1, wherein, Step (b) involves adjusting the pH of the raw material solution with concentrated hydrochloric acid.