High-performance catalyst for preparing concentrated formaldehyde through oxidation of methylene dimethyl diether as well as preparation method and application of high-performance catalyst

Abstract

The invention belongs to the field of low-carbon chemical industry, and particularly relates to a high-performance catalyst for preparing concentrated formaldehyde through oxidation of methylene dimethyl diether as well as a preparation method and application of the high-performance catalyst. The invention discloses a high-performance catalyst for preparing concentrated formaldehyde through oxidation of methylene dimethyl diether. The high-performance catalyst is composed of Mo, Fe, X and O elements, and the chemical formula of the catalyst is Mo alpha * Fe beta * X gamma * O delta, wherein X is Se or Te, alpha is 0.9-3.0, beta is 0.6-1.5, gamma is 0.001-0.1, and delta is a positive number for keeping the algebraic sum of valence of each element to be 0. The catalyst is a ternary bulk type inorganic material with a composite oxide structure, the components are uniformly dispersed, the synergistic effect is remarkable, the catalyst is high in activity, good in selectivity, good in stability, low in cost and stable and repeatable in structure and performance, the catalyst is excellent in performance when used for producing concentrated formaldehyde through oxidation of methylene dimethyl diether, and the catalyst is suitable for industrial production. The method is especially suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of low-carbon chemical engineering, and relates to a high-performance ternary catalytic material, specifically a high-performance catalyst for the oxidation of methylene dimethyl ether to concentrated formaldehyde, its preparation method and application. Background Art

[0002] Formaldehyde is an important organic chemical raw material and a common platform molecule. The industrial methods for producing formaldehyde are divided into the "silver method" and the "iron-molybdenum method". The "silver method" usually can produce an aqueous formaldehyde solution with a concentration of 37-45 wt%, while the "iron-molybdenum method" can produce an aqueous formaldehyde solution with a concentration of 50-60 wt%.

[0003] In recent years, with the accelerating speed of industrial transformation and upgrading in China, the country's demand for advanced materials and technologies has been increasing day by day. High-tech industries such as photovoltaic, new energy vehicles, intelligent electronics, and e-commerce have developed vigorously, driving the rapid development of special adhesives, high-performance polymer materials, and degradable plastics, and further driving the rapid growth of chemicals such as polyoxymethylene, 1,4-butanediol, acrylic acid, methyl methacrylate, and polymethoxydimethylether. The production of these chemicals all requires concentrated formaldehyde as a raw material. For example, the production of methyl methacrylate requires a concentrated formaldehyde solution with a concentration of more than 75 wt%. Obviously, the formaldehyde produced by the "silver method" and the "iron-molybdenum method" cannot meet this requirement, and it needs to be further concentrated to obtain concentrated formaldehyde with a concentration of more than 75 wt%. To separate the excess water in the formaldehyde solution, not only special separation equipment needs to be manufactured, but also a large amount of steam is consumed. Because formaldehyde and water form an azeotrope, the latent heat of vaporization of water is large, and formic acid will be generated when formaldehyde is concentrated, which will corrode the equipment.

[0004] The oxidation method of methylene dimethyl ether can theoretically produce an aqueous formaldehyde solution with a maximum concentration of 83.3 wt%, and is expected to directly produce concentrated formaldehyde that meets the above requirements without a concentration process, thus greatly reducing equipment costs and operating costs. It is a more advanced concentrated formaldehyde production technology than the "silver method" and the "iron-molybdenum method". Methylene dimethyl ether is a chemical synthesized by the condensation of methanol and formaldehyde under the action of an acidic catalyst. There are mature industrial production technologies developed in China, but the technology for the oxidation of methylene dimethyl ether to concentrated formaldehyde has not been industrialized in China yet. Only a very small number of countries in the world have industrial production technologies. One of the key technologies for the oxidation of methylene dimethyl ether to concentrated formaldehyde is the catalyst, and high-performance catalysts that can be used in the industrial production of concentrated formaldehyde have not been developed in China yet.

[0005] In laboratories, the co - precipitation method is basically used to prepare catalysts for the oxidation of methylene dimethyl ether to concentrated formaldehyde. The catalysts mainly consist of three elements: molybdenum, iron, and oxygen. Some units have also tried to add additives such as chromium, cobalt, vanadium, and nickel. Although certain progress has been made in the small - scale research of catalysts using this method and formula, the selectivity of the catalysts still needs to be improved. Moreover, this method has a long preparation process and cycle, losses of iron and molybdenum elements, generates a large amount of wastewater, and the prepared catalysts have a relatively high molybdenum - iron ratio. Summary of the Invention

[0006] The purpose of the present invention is to provide a high - performance catalyst for the oxidation of methylene dimethyl ether to concentrated formaldehyde in view of the technical problems existing in the prior art. This catalyst can be preferably used in the industrial production of high - concentration formaldehyde by the oxidation of methylene dimethyl ether. The mass fraction of formaldehyde in the produced concentrated formaldehyde can reach more than 80%, and it can be directly used as the raw material required for the production of downstream chemicals.

[0007] In order to achieve the purpose of the present invention, the specific technical solution of the present invention is as follows:

[0008] A high - performance catalyst for the oxidation of methylene dimethyl ether to concentrated formaldehyde, wherein the catalyst is composed of Mo, Fe, X, and O elements, and its chemical formula is Mo α ·Fe β ·X γ ·O δ , where X is Se or Te, and α, β, γ, δ are the stoichiometric numbers of each atom. α is 0.9 - 3.0 (specifically, it can be 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, etc.), β is 0.6 - 1.5 (specifically, it can be 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, etc.), γ is 0.001 - 0.1 (specifically, it can be 0.001, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc.), and δ is a positive number that keeps the algebraic sum of the valences of each element equal to 0.

[0009] Furthermore, the high - performance catalyst for the oxidation of methylene dimethyl ether to concentrated formaldehyde described above is a ternary bulk - type inorganic material with a composite oxide structure.

[0010] Furthermore, for the high - performance catalyst for the oxidation of methylene dimethyl ether to concentrated formaldehyde described above, its active component is Fe2(MoO4)3, and X is an additive.

[0011] Furthermore, for the high-performance catalyst for oxidizing methylene dimethyl ether to concentrated formaldehyde described above, the molar ratio of Mo to Fe is 1.50 - 1.74 (specifically, it can be 1.50, 1.51, 1.52, 1.53, 1.54, 1.55, 1.56, 1.57, 1.58, 1.59, 1.60, 1.61, 1.62, 1.63, 1.64, 1.65, 1.66, 1.67, 1.68, 1.69, 1.70, 1.71, 1.72, 1.73, 1.74, etc.).

[0012] For the ternary bulk catalyst with a composite oxide structure described above, it can be prepared by a stepwise wet mixing process. The preparation method includes the following steps:

[0013] 1) Weigh industrial-grade MoO3, Fe(NO)3·9H2O, and the raw material containing Se or Te in proportion, and then grind them finely and mix them evenly to obtain material A;

[0014] 2) Grind MoO3 finely under the action of a solvent to obtain material B;

[0015] 3) Add material A to material B, grind them finely and mix them evenly to obtain material C;

[0016] 4) Calcinate and form material C to obtain a ternary bulk catalyst with a composite oxide structure, namely Mo α ·Fe β ·X γ ·O δ .

[0017] Furthermore, in step 1), the raw material containing Se or Te is H2SeO4 or SeO2, H6TeO6 or TeO3;

[0018] Furthermore, in step 2), the solvent is methanol, ethanol, ethylene glycol or glycerol.

[0019] Furthermore, in step 4), the calcination temperature is 490 - 540 °C (specifically, it can be 490 °C, 500 °C, 510 °C, 520 °C, 530 °C, 540 °C, etc.), and the time is 1.0 - 5.0 h (specifically, it can be 1.0 h, 1.5 h, 2.0 h, 2.5 h, 3.0 h, 3.5 h, 4.0 h, 4.5 h, 5.0 h, etc.).

[0020] When preparing the high-performance catalyst for oxidizing methylene dimethyl ether to concentrated formaldehyde described above, this stepwise wet mixing process does not require filtration, washing, and drying, and has few steps; the grinding and mixing process is carried out at room temperature, with low energy consumption and short time; no wastewater or solid waste is generated during the whole process, solving the problems of molybdenum loss and iron loss, being green, economical and environmentally friendly; and greatly reducing the processing cost of the catalyst.

[0021] In addition, the crystal water in Fe(NO)3·9H2O is conducive to the sufficient grinding and uniform mixing of Fe(NO)3·9H2O, H2SeO4 (SeO2 is also acceptable) or H6TeO6 (TeO3 is also acceptable); methanol, ethanol, ethylene glycol or glycerol are all solvents rich in hydroxyl groups. The excellent affinity adsorption of hydroxyl groups not only helps to grind MoO3 finely and disperse it evenly, but also helps to form a strong interaction between Fe(NO)3·9H2O, H2SeO4 (SeO2 is also acceptable) or H6TeO6 (TeO3 is also acceptable) and the surface of molybdenum trioxide, which is conducive to the sufficient grinding and uniform mixing of MoO3, Fe(NO)3·9H2O, H2SeO4 (SeO2 is also acceptable) or H6TeO6 (TeO3 is also acceptable), and finally forms a stable and reproducible ternary bulk catalyst Mo α ·Fe β ·X γ ·O δ , so as to give full play to the synergistic effect of each component and improve the activity, selectivity and stability of the catalyst.

[0022] Another object of the present invention is to protect the application of the above-mentioned catalyst in the catalytic oxidation of methylene dimethyl ether to concentrated formaldehyde products.

[0023] Furthermore, in the catalytic oxidation of methylene dimethyl ether to concentrated formaldehyde using the above-mentioned catalyst, the single-pass conversion rate of methylene dimethyl ether can reach 100%; the mass fraction of formaldehyde in the produced concentrated formaldehyde can reach 80%.

[0024] Furthermore, the concentrated formaldehyde product can be directly used as a raw material required for the production of downstream chemicals.

[0025] Compared with the existing technology, the beneficial effects of the present invention are:

[0026] (1) Se and Te are elements in Group VI A of the oxygen family, with a maximum valence of +6, and can also exist in valence states of -2, -1, 0, +1, +2, +4, etc. Depending on the environment, these two elements can have variable valences. When Se or Te is used as an additive and exists in a high valence state, when the oxidation reaction of methylene dimethyl ether occurs, Se or Te is reduced to a low valence state, and then quickly oxidized to a high valence state by O2 in the reaction gas stream, and so on in a cycle. As an efficient oxygen carrier, Se or Te transfers the oxygen in the gas stream to the product, and cooperates with Fe2(MoO4)3, which is not only conducive to the full conversion of the raw material methylene dimethyl ether, but also conducive to the conversion of the intermediate product methanol into formaldehyde, and is also conducive to the long-term stable operation of the catalyst. In addition, the content of Se or Te is low, which reduces the raw material cost of the catalyst.

[0027] (2) The relatively low molybdenum-to-iron ratio (1.50 - 1.74) in the present invention can increase the mass fraction of the active component Fe2(MoO4)3 in the catalyst while ensuring the full combination of Mo and Fe, thereby improving the catalyst performance. In addition, it also significantly reduces the raw material cost of the catalyst.

[0028] (3) The catalyst in the present invention is a ternary bulk inorganic material Mo with a composite oxide structure α ·Fe β ·X γ ·O δ . Each component of the catalyst has good dispersibility and significant synergistic effect. The catalyst structure and performance are stable and reproducible, with excellent activity, selectivity, and stability, and is particularly suitable for industrial production.

[0029] (4) The single-pass conversion rate of methylene dimethyl ether on the catalyst in the present invention can reach 100%, and the mass fraction of formaldehyde in the produced concentrated formaldehyde can reach 80%. This concentrated formaldehyde product can be directly used as the raw material required for downstream chemical production. Detailed Embodiments

[0030] All the features disclosed in this specification, or all the steps in the disclosed methods or processes, except for mutually exclusive features and / or steps, can be combined in any manner.

[0031] Any feature disclosed in this specification (including claims, abstract) can be replaced by other equivalent or similar-purpose alternative features unless specifically stated. That is, unless specifically stated, each feature is only an example of a series of equivalent or similar features.

[0032] The features and performance of the present invention will be further described in detail below in conjunction with examples.

[0033] Example 1

[0034] First, weigh 1000.0 g, 1858.5 g, and 90.6 g of industrial-grade MoO3, Fe(NO)3·9H2O, and H2SeO4 respectively; secondly, after mixing the weighed Fe(NO)3·9H2O and H2SeO4, grind them finely and mix them evenly to obtain material A; then, add 194 mL of ethylene glycol to the weighed MoO3, mix and grind them finely to make them evenly dispersed to obtain material B; then add material A to material B, grind and mix them finely and evenly to obtain material C; finally, calcine material C at 500 °C for 4.5 h and then form it to obtain a ternary bulk catalyst Mo with a composite oxide structure 1.00 ·Fe 0.66 ·Se 0.09 ·O 4.17 .

[0035] The catalyst Mo 1.00 ·Fe 0.66 ·Se 0.09 ·O 4.17 is used in the production of concentrated formaldehyde by catalytic oxidation of methylene dimethyl ether. Under the process conditions of normal pressure, a temperature of about 269.0 °C, and a liquid hourly space velocity of methylene dimethyl ether of about 0.8 h -1 , the reaction products are absorbed by ethanol, and the obtained liquid and gas phase products are respectively analyzed by chromatography. Through carbon balance, catalytic performance indicators and product composition calculation, the single-pass conversion rate of methylene dimethyl ether on this catalyst is 100.0%, the selectivity of formaldehyde is 95.5%, and the mass fraction of formaldehyde in the produced concentrated formaldehyde is 81.7%.

[0036] Example 2

[0037] First, weigh 1000.0 g, 1754.0 g, and 1.4 g of industrial-grade MoO3, Fe(NO)3·9H2O, and SeO2 respectively; secondly, after mixing the weighed Fe(NO)3·9H2O and SeO2, grind them finely and mix them evenly to obtain material A; then, add 281 mL of methanol to the weighed MoO3, mix and grind them finely to make them evenly dispersed to obtain material B; then add material A to material B, grind and mix them finely and evenly to obtain material C; finally, calcine material C at 510 °C for 3.5 h and then form it to obtain a ternary bulk catalyst Mo 1.63 ·Fe 1.02 ·Se 0.003 ·O 6.426 .

[0038] The catalyst Mo 1.63 ·Fe 1.02 ·Se 0.003 ·O 6.426 is used in the production of concentrated formaldehyde by catalytic oxidation of methylene dimethyl ether. Under the process conditions of normal pressure, a temperature of about 356.8 °C, and a liquid hourly space velocity of methylene dimethyl ether of about 2.5 h -1 , the reaction products are absorbed by ethanol, and the obtained liquid and gas phase products are respectively analyzed by chromatography. Through carbon balance, catalytic performance indicators and product composition calculation, the single-pass conversion rate of methylene dimethyl ether on this catalyst is 100.0%, and the mass fraction of formaldehyde in the produced concentrated formaldehyde is 82.5%.

[0039] Example 3

[0040] First, weigh 1000.0 g, 1612.9 g, and 30.6 g of industrial-grade MoO3, Fe(NO)3·9H2O, and H6TeO6 respectively. Secondly, after mixing the weighed Fe(NO)3·9H2O and H6TeO6, grind them finely and mix them evenly to obtain Material A. Then, add 169 mL of glycerol to the weighed MoO3, mix them and grind finely to make them evenly dispersed, obtaining Material B. Next, add Material A to Material B, grind them finely and mix them evenly to obtain Material C. Finally, calcine Material C at 530 °C for 2.0 h and then form it to obtain a ternary bulk catalyst Mo 2.61 ·Fe 1.50 ·Te 0.05 ·O 10.155 。

[0041] Use this catalyst Mo 2.61 ·Fe 1.50 ·Te 0.05 ·O 10.155 in the oxidation of methylene dimethyl ether to concentrated formaldehyde production. Under the process conditions of normal pressure, a temperature of about 320 °C, and a liquid hourly space velocity of methylene dimethyl ether of about 1.5 h -1 , the reaction runs continuously for 1500 h. The products are absorbed by ethanol, and the obtained liquid-phase and gas-phase products are analyzed by chromatography respectively. After calculating the carbon balance, catalytic performance indicators, and product composition, the results at the beginning and end of the reaction are selected and listed in the following table:

[0042]

[0043]

[0044] Comparative Example 1

[0045] First, weigh 1000.0 g and 1858.5 g of industrial-grade MoO3 and Fe(NO)3·9H2O respectively. Secondly, grind the weighed Fe(NO)3·9H2O finely to obtain Material A. Then, add 194 mL of ethylene glycol to the weighed MoO3, mix them and grind finely to make them evenly dispersed, obtaining Material B. Next, add Material A to Material B, grind them finely and mix them evenly to obtain Material C. Finally, calcine Material C at 500 °C for 4.5 h and then form it to obtain a ternary bulk catalyst Mo 1.00 ·Fe 0.66 ·O 3.99 。

[0046] Use this catalyst Mo 1.00 ·Fe 0.66 ·O 3.99For the production of concentrated formaldehyde by catalyzing the oxidation of methylene dimethyl ether, under the process conditions of normal pressure, a temperature of about 270.0 °C, and a liquid hourly space velocity of methylene dimethyl ether of about 0.8 h -1 The reaction products were absorbed by ethanol, and the obtained liquid and gas phase products were analyzed by chromatography respectively. Through carbon balance, catalytic performance index and product composition calculation, the single-pass conversion rate of methylene dimethyl ether on this catalyst was 99.0%, the selectivity of formaldehyde was 84.8%, and the mass fraction of formaldehyde in the produced concentrated formaldehyde was 72.1%.

[0047] Comparative Example 2

[0048] First, weigh 625.0 g, 1754.0 g, and 1.4 g of industrial-grade MoO3, Fe(NO)3·9H2O, and SeO2 respectively; secondly, mix the weighed Fe(NO)3·9H2O and SeO2, grind them finely and mix them evenly to obtain Material A; then, add 176 mL of methanol to the weighed MoO3, mix and grind it finely to make it evenly dispersed to obtain Material B; then add Material A to Material B, grind it finely and mix it evenly to obtain Material C; finally, calcine Material C at 510 °C for 3.5 h and then form it to obtain a ternary bulk catalyst Mo 1.02 ·Fe 1.02 ·Se 0.003 ·O 4.596 。

[0049] Use this catalyst Mo 1.02 ·Fe 1.02 ·Se 0.003 ·O 4.596 For the production of concentrated formaldehyde by catalyzing the oxidation of methylene dimethyl ether, under the process conditions of normal pressure, a temperature of about 356.2 °C, and a liquid hourly space velocity of methylene dimethyl ether of about 2.5 h -1 The reaction products were absorbed by ethanol, and the obtained liquid and gas phase products were analyzed by chromatography respectively. Through carbon balance, catalytic performance index and product composition calculation, the single-pass conversion rate of methylene dimethyl ether on this catalyst was 95.5%, and the mass fraction of formaldehyde in the produced concentrated formaldehyde was 71.9%.

[0050] Comparative Example 3

[0051] First, weigh 1000.0 g, 1612.9 g, and 305.6 g of industrial-grade MoO3, Fe(NO)3·9H2O, and H6TeO6 respectively. Secondly, after mixing the weighed Fe(NO)3·9H2O and H6TeO6, grind them finely and mix them evenly to obtain material A. Then, add 169 mL of glycerol to the weighed MoO3, mix and grind them finely to make them evenly dispersed to obtain material B. Next, add material A to material B, grind them finely and mix them evenly to obtain material C. Finally, calcine material C at 530 °C for 2.0 h and then form it to obtain a ternary bulk catalyst Mo 2.61 ·Fe 1.50 ·Te 0.5 ·O 11.58 。

[0052] Use this catalyst Mo 2.61 ·Fe 1.50 ·Te 0.5 ·O 11.58 in the oxidation of methylene dimethyl ether to concentrated formaldehyde production. Under the process conditions of normal pressure, a temperature of about 320 °C, and a liquid hourly space velocity of methylene dimethyl ether of about 1.5 h -1 , the reaction runs continuously for 1500 h. The product is absorbed by ethanol, and the obtained liquid and gas phase products are analyzed by chromatography respectively. After calculating the carbon balance, catalytic performance indicators, and product composition, the results at the beginning and end of the reaction are selected and listed in the following table:

[0053]

[0054] It can be seen from Examples 1-3 that: the catalyst obtained by the present invention shows excellent performance in the oxidation of methylene dimethyl ether to concentrated formaldehyde production. Methylene dimethyl ether can be completely converted, the mass fraction of formaldehyde in concentrated formaldehyde can reach more than 80%, and it can operate stably for a long time.

[0055] The above-described embodiments only represent the specific implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation to the protection scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the technical solution of the present application, several deformations and improvements can be made, and these all belong to the protection scope of the present application.

[0056] This background technology section is provided to generally present the context of the present invention. The work of the currently named inventors, the work described in this background technology section, and aspects that are not prior art at the time of filing this application are neither expressly nor implicitly admitted to be prior art of the present invention.

Claims

1. A high-performance catalyst for preparing concentrated formaldehyde by oxidation of methylene dimethyl diether, characterized in that: The catalyst is composed of Mo, Fe, X, and O elements, and its chemical formula is Mo α ·Fe β ·X γ ·O δ ; Wherein, X is Se or Te, α is 0.9-3.0, β is 0.6-1.5, γ is 0.001-0.1, and δ is a positive number that keeps the algebraic sum of the valences of each element equal to 0.

2. The high-performance catalyst for preparing concentrated formaldehyde by oxidation of methylene dimethyl diether as claimed in claim 1, characterized in that: The catalyst is a ternary bulk inorganic material with a composite oxide structure.

3. The high-performance catalyst for preparing concentrated formaldehyde by oxidation of methylene dimethyl diether as claimed in claim 1 or 2, characterized in that: The active component of the catalyst is Fe2(MoO4)3, and X is an auxiliary agent.

4. A high-performance catalyst for preparing concentrated formaldehyde by oxidation of methylene dimethyl diether as claimed in any one of claims 1 to 3, characterized in that: The molar ratio of Mo to Fe in the catalyst is 1.50-1.

74.

5. Use of the catalyst as claimed in any one of claims 1 to 4 in the catalytic oxidation of methylene dimethyl diether to produce concentrated formaldehyde.

6. Use of the catalyst as claimed in claim 5 in the catalytic oxidation of methylene dimethyl diether to produce concentrated formaldehyde, characterized in that: The mass fraction of formaldehyde in the concentrated formaldehyde is above 80%.

7. A method for preparing a high-performance catalyst for preparing concentrated formaldehyde by oxidation of methylene dimethyl diether as claimed in any one of claims 1 to 4, characterized in that The following steps are involved: 1) MoO3, Fe(NO)3·9H2O, and raw materials containing Se or Te are weighed in proportion, and then fully ground and mixed to obtain material A; 2) Grinding MoO3 fully under the action of a solvent to obtain material B; 3) Add material A to material B, grind them thoroughly and mix them evenly to obtain material C; 4) Calcinate and shape material C to obtain a ternary bulk catalyst having a composite oxide structure, namely, Mo α ·Fe β ·X γ ·O δ .

8. The method for preparing a high-performance catalyst for preparing concentrated formaldehyde by oxidation of methylene dimethyl diether as claimed in claim 7, characterized in that: The raw material containing Se or Te in step 1) is H2SeO4 or SeO2, H6TeO6 or TeO3.

9. The method for preparing a high-performance catalyst for preparing concentrated formaldehyde by oxidation of methylene dimethyl diether as claimed in claim 7, characterized in that: The solvent described in step 2) is methanol, ethanol, ethylene glycol or glycerol.

10. The method for preparing a high-performance catalyst for preparing concentrated formaldehyde by oxidation of methylene dimethyl diether as claimed in claim 7, characterized in that: The calcination temperature in step 4) is 490-540°C and the calcination time is 1.0-5.0h.

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