Preparation method of supported catalyst and application of supported catalyst in preparation of hexanediol

Abstract

The invention relates to the technical field of catalysts, and particularly discloses a preparation method of a supported catalyst and application of the supported catalyst in preparation of hexanediol. When the catalyst is prepared, the carrier is placed in organic acid for acidification treatment, then an auxiliary agent precursor solution is added for mixing, then a precipitant is added for mixing, and a composite carrier is obtained; dipping the composite carrier into an active component salt solution, and finally filtering, washing, drying and roasting to obtain the supported catalyst. The preparation method of the catalyst is simple, the problems that the catalyst is low in activity and easy to lose are solved, and the catalyst shows relatively high activity and selectivity in a hexanediol preparation process.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a method for preparing a supported catalyst and its application in the preparation of hexanediol. Background Technology

[0002] 1,6-Hexanediol (HDO) is a high-value-added fine chemical product widely used in polyurethane, synthetic resin additives, pharmaceutical intermediates, and UV curing agents. Furthermore, traditional resins and coatings modified with HDO exhibit significantly improved water resistance, mechanical strength, oxidation resistance, and environmental friendliness. It is a chemical product with enormous market potential.

[0003] The main methods for preparing 1,6-hexanediol include hydroformylation, catalytic conversion of 1,2,6-hexanetriol, catalytic conversion of 5-hydroxymethylfurfural, catalytic hydrogenation of adipic acid, sorbitol cracking, and catalytic hydrogenation of dialkyl adipate esters. Currently, the production of 1,6-hexanediol mainly adopts the adipic acid esterification-hydrogenation method. First, dimethyl adipate is prepared by esterification, and then dimethyl adipate is hydrogenated. This technology has mild conditions, readily available raw materials, generates less waste, has a high reaction yield, and low production cost. The key to the hydrogenation of dimethyl adipate to 1,6-hexanediol lies in the catalyst; therefore, developing a novel, highly efficient catalyst is crucial to achieving this reaction.

[0004] CN101113128A discloses a Cu-Zn-Al catalyst for the hydrogenation of dimethyl adipate to 1,6-hexanediol. The catalyst is prepared by co-precipitation of a Cu(NO3)2 and Zn(NO3)2 mixed solution with Al(OH)3 to form a suspension. The suspension is then subjected to precipitation, filtration, washing, drying, granulation, calcination, mixing with a premixing agent, and tableting. The reaction is carried out at a pressure of 7 MPa, a temperature of 300 °C, and a space velocity of 0.2 h⁻¹. -1 Under the condition of a hydrogen-to-ester ratio of 120, the conversion rate of dimethyl adipic acid is greater than 99%, and the selectivity of 1,6-hexanediol can reach up to 98.14%. However, the catalyst can only be used at a low space velocity, resulting in low production capacity. Therefore, the catalyst cost is high in large-scale industrial applications. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for preparing a supported catalyst and its application in the preparation of hexanediol. This catalyst overcomes the problems of incomplete catalyst precipitation, uneven distribution, poor activity, easy deactivation, and short lifespan in the prior art, and has the advantages of high activity, high selectivity, high stability, and easy regeneration.

[0006] The technical solution of the present invention is a method for preparing a supported catalyst, comprising the following steps: S1. The carrier is placed in an organic acid for acidification, then an auxiliary precursor solution is added and mixed, and then a precipitant is added and mixed to obtain a composite carrier. S2. The composite support is impregnated into the active component salt solution, and then filtered, washed, dried and calcined to obtain the supported catalyst.

[0007] Optionally, the carrier is one of Al2O3, ZSM-5, [B]-MFI, MCM-41, TS, MOR, SBA-15, MCM-48 and KIT-6; the organic acid is one of maleic acid, citric acid, lactic acid, acetic acid, succinic acid, benzoic acid and dodecylbenzenesulfonic acid.

[0008] Optionally, the additive is one of manganese dioxide, chromium trioxide, nickel oxide, zinc oxide, magnesium oxide, and cerium dioxide; the additive precursor solution is a nitrate solution of the additive.

[0009] Optionally, the mass ratio of the adjuvant to the carrier in S1 is 1 to 5:1.

[0010] Optionally, the precipitant is one of sodium carbonate, sodium hydroxide, potassium carbonate, and potassium hydroxide.

[0011] Optionally, the active component is copper oxide; the active component salt solution is one of copper nitrate, copper sulfate, copper carbonate, and copper acetate.

[0012] Optionally, the mass concentration of the active component salt solution is 10-50%wt.

[0013] Optionally, the mass ratio of the carrier, auxiliaries, and active components is (1-30):(10-50):(30-60).

[0014] The present invention also relates to the use of the catalyst as a catalyst for the hydrogenation of dimethyl adipate to hexanediol.

[0015] Optionally, when preparing hexanediol by hydrogenation of dimethyl adipate, the concentration of dimethyl adipate is 5-60%, and the space velocity is 0.1-1.0 h⁻¹. -1 The reaction pressure is 4-9 MPa, the reaction time is 1-5 h, the reaction temperature is 170-250 ℃, and the hydrogen-ester ratio is 100-700:1.

[0016] The present invention has the following beneficial effects: 1. The catalysts for the hydrogenation of dimethyl adipic acid to hexanediol are mainly copper-based catalysts, with Cu being the primary active component. 0 / Cu + The main process involves reducing copper oxide with hydrogen to convert some of it into zero-valent copper, where Cu... 0 This allows Cu to provide adsorption sites for H2. +It can polarize dimethyl adipate molecules to directly affect the reaction rate of ester hydrogenation, while Cu 0 / Cu + The synergistic effect greatly increases the activity of the catalyst.

[0017] 2. In this invention, the carrier is first acidified, then mixed with the additives for co-precipitation, and finally impregnated with the active component solution. This method avoids the problems of incomplete precipitation, uneven stepwise precipitation, and poor activity caused by co-precipitation of multiple components together.

[0018] 3. This catalyst uses molecular sieves as a support. Molecular sieves possess a unique cross-channel structure, and the cavities formed at the channel intersections are concentrated areas of catalytic active centers. The absence of large cavities at these intersections restricts macromolecular polymerization, significantly reducing the carbon deposition rate and preventing deactivation due to carbon buildup of active components. Acidification treatment of the molecular sieve maintains its framework and cross-channel structure while enhancing acidity. Simultaneously, some framework structures change from Si-O-Al to Si-OH, forming a multi-level pore structure of micropores and mesopores. This further improves diffusion performance and resistance to carbon deposition, thereby increasing catalyst utilization efficiency and lifespan. The supported catalyst obtained by this method exhibits high activity, is simple to process, and can be used for industrial production. Attached Figure Description

[0019] Figure 1 This is the gas chromatogram of hexanediol. Detailed Implementation

[0020] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods. Unless otherwise specified, the raw materials or reagents used are commercially available. The embodiments of the present invention will be described in detail below with reference to the examples; however, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention.

[0021] Example 1: 2g of activated alumina was soaked in 20ml of 2% acetic acid solution and stirred at 100℃ for 3h. After filtration, the support and 19g of zinc nitrate aqueous solution were mixed and stirred at 60℃ for 3h. After stirring, the support and 30g of sodium carbonate solution were added to the reaction flask in parallel at a rate of 1 drop / 1 second, maintaining the pH at 7. The mixture was stirred at 60℃ for 4h, filtered, washed until neutral, and dried. The composite support was then impregnated in 50%wt copper nitrate solution and stirred at 80℃ for 10h. After filtration, washing, drying, and calcination, catalyst 1 was obtained.

[0022] The catalyst obtained in Example 1 was used in the hydrogenation of dimethyl adipate to prepare hexanediol, using a 20% dimethyl adipate solution and a space velocity of 0.5 h⁻¹. -1The reaction pressure was 5 MPa, the reaction time was 3 h, the reaction temperature was 210 °C, and the hydrogen-to-ester ratio was 400:1. The product was analyzed by gas phase. The results are shown in Table 1.

[0023] Example 2: 2g of [B]-MFI was soaked in 20ml of 5% maleic acid solution and stirred at 120℃ for 3h. After filtration, the support and 16g of nickel nitrate aqueous solution were mixed and stirred at 60℃ for 3h. After stirring, the support and 26g of sodium carbonate solution were added to the reaction flask in parallel at a rate of 1 drop / 20 seconds, maintaining the pH at 7. The mixture was stirred at 60℃ for 5h, filtered, washed until neutral, and dried. The composite support was then impregnated in 40%wt copper nitrate solution and stirred at 100℃ for 10h. After filtration, washing, drying, and calcination, catalyst 2 was obtained.

[0024] The catalyst obtained in Example 2 was used in the hydrogenation of dimethyl adipate to prepare hexanediol under the same reaction conditions as in Example 1. The results are shown in Table 1.

[0025] Example 3: 2.3g of SBA-15 was soaked in 20ml of 10% benzoic acid solution and stirred at 150℃ for 5h. After filtration, the support and 30g of chromium nitrate aqueous solution were mixed and stirred at 50℃ for 5h. After stirring, 48g of sodium hydroxide solution was added to the reaction flask in parallel at a rate of 1 drop / 5 seconds, maintaining the pH at 7. The mixture was stirred at 50℃ for 7h, filtered, washed until neutral, and dried. The composite support was then impregnated in 50% wt copper acetate solution and stirred at 90℃ for 15h. After filtration, washing, drying, and calcination, catalyst 3 was obtained.

[0026] The catalyst obtained in Example 3 was used in the experiment of hydrogenating dimethyl adipate to prepare hexanediol. The reaction conditions were the same as in Example 1, and the results are shown in Table 1.

[0027] Example 4: 2g of MCM-41 was soaked in 20ml of 5% lactic acid solution and stirred at 100℃ for 10h. After filtration, the support and 21g of cerium nitrate aqueous solution were mixed and stirred at 80℃ for 8h. After stirring, 42g of sodium hydroxide solution was added to the reaction flask in parallel at a rate of 1 drop / 10 seconds, maintaining the pH at 7. The mixture was stirred at 80℃ for 4h, filtered, washed until neutral, and dried. The composite support was then impregnated in 30%wt copper sulfate solution and stirred at 80℃ for 20h. After filtration, washing, drying, and calcination, catalyst 4 was obtained.

[0028] The catalyst obtained in Example 4 was used in the experiment of hydrogenating dimethyl adipate to prepare hexanediol. The reaction conditions were the same as in Example 1, and the results are shown in Table 1.

[0029] Table 1

[0030] As shown in Table 1, the catalysts prepared using activated alumina, [B]-MFI, SBA-15, and MCM-41 as supports, zinc nitrate, nickel nitrate, chromium nitrate, and cerium nitrate as precursors, and copper nitrate, copper acetate, and copper sulfate as active component precursors exhibit varying activities. The catalyst prepared using [B]-MFI, nickel nitrate, and copper nitrate shows the highest activity, achieving a dimethyl adipic acid conversion rate of over 99.9% and a hexanediol selectivity of 100%. This is mainly attributed to the unique cross-pore structure of the [B]-MFI support, which significantly enhances the catalyst's activity. The catalysts prepared using the other molecular sieve supports also exhibit relatively high activity. However, compared to catalyst 2, the catalyst activity is slightly lower, and catalyst 1 shows the worst performance.

[0031] Comparative Example 1: 2g of [B]-MFI support and 16g of nickel nitrate aqueous solution were mixed and stirred at 60℃ for 3h. After stirring, 26g of sodium carbonate solution was added to the reaction flask in parallel at a rate of 1 drop / 20 seconds, while maintaining the pH at 7. The mixture was stirred at 60℃ for 5h, filtered, washed until neutral, and dried. The composite support was then impregnated in 40%wt copper nitrate solution and stirred at 100℃ for 10h. After filtration, washing, drying, and calcination, comparative catalyst 1 was obtained.

[0032] The catalyst obtained in Comparative Example 1 was used in the experiment of hydrogenating dimethyl adipate to prepare hexanediol. The reaction conditions were the same as in Example 1, and the results are shown in Table 2.

[0033] Comparative Example 2: 2g of [B]-MFI was soaked in 20ml of 5% maleic acid solution and stirred at 120℃ for 3h. After filtration, the support and 16g of nickel nitrate aqueous solution were mixed and stirred at 60℃ for 3h. After stirring, 26g of sodium carbonate solution was added to the composite support solution at a rate of 1 drop / 20 seconds, maintaining the pH at 7. The mixture was stirred at 60℃ for 5h, filtered, washed until neutral, and dried. The composite support was then impregnated in 40%wt copper nitrate solution and stirred at 100℃ for 10h. After filtration, washing, drying, and calcination, comparative catalyst 2 was obtained.

[0034] The catalyst obtained in Comparative Example 2 was used in the hydrogenation of dimethyl adipate to prepare hexanediol under the same reaction conditions as in Example 1. The results are shown in Table 2.

[0035] Comparative Example 3: 2g of [B]-MFI was soaked in 20ml of 5% maleic acid solution and stirred at 120℃ for 3h. After filtration, the support, 16g of nickel nitrate aqueous solution and 8.5g of copper nitrate were mixed and stirred at 60℃ for 3h. After stirring, it was added to the reaction flask in parallel with 26g of sodium carbonate solution at a rate of 1 drop / 20 seconds. The pH was maintained at 7 and stirred at 60℃ for 5h. After filtration, the mixture was washed until neutral, dried and calcined to obtain the comparative catalyst 3.

[0036] The catalyst obtained in Comparative Example 3 was used in the experiment of hydrogenating dimethyl adipate to prepare hexanediol. The reaction conditions were the same as in Example 1, and the results are shown in Table 2.

[0037] Table 2

[0038] Comparing the results in Table 2, Comparative Example 1 catalyst, prepared by directly combining the support and additives without acidification treatment, showed slightly reduced activity, with decreased conversion of dimethyl adipate and selectivity of hexanediol. Comparative Example 2 catalyst, prepared by adding a precipitant to the composite support solution using an additive co-precipitation method, also showed relatively reduced activity, though slightly higher than Comparative Example 1. Comparative Example 3 catalyst, prepared by mixing the active component and additives together and using a co-current precipitation method, showed slightly reduced activity compared to catalysts prepared by impregnation of the active component, primarily due to component loss.

[0039] Example 5: The used catalyst 2 was removed and separated, and then calcined at 450°C for 2 hours in a nitrogen atmosphere to obtain regenerated catalyst 1.

[0040] The regenerated catalyst 1 was used in the experiment of hydrogenating dimethyl adipate to prepare hexanediol under the same reaction conditions as in Example 1. The results are shown in Table 3.

[0041] The used regenerated catalyst 1 was removed and separated, and then calcined at 450°C for 2 hours in a nitrogen atmosphere to obtain regenerated catalyst 2.

[0042] The regenerated catalyst 2 was used in the experiment of hydrogenating dimethyl adipate to prepare hexanediol under the same reaction conditions as in Example 1. The results are shown in Table 3.

[0043] The used regenerated catalyst 2 was removed and separated, and then calcined at 450°C for 2 hours in a nitrogen atmosphere to obtain regenerated catalyst 3.

[0044] The regenerated catalyst 3 was used in the experiment of hydrogenating dimethyl adipate to prepare hexanediol under the same reaction conditions as in Example 1. The results are shown in Table 3.

[0045] Table 3

[0046] As shown in Table 3, after catalyst 2 was regenerated and reused 3 times, the conversion rate of dimethyl adipic acid decreased by 0.03 percentage points, and the overall decreasing trend was not obvious. However, the selectivity of hexanediol remained unchanged, indicating that the catalyst can still maintain high catalytic activity after multiple reuses. The catalyst has high stability and can be reused and industrialized.

[0047] Figure 1 The relevant gas chromatographic qualitative spectra show the solvent peak at 1.703 min, the dimethyl adipate peak at 8.068 min, the methyl 6-hydroxyhexanoate peak at 9.802 min, and the hexanediol peak at 11.465 min.

[0048] The above embodiments describe preferred embodiments of the present invention, but the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other way. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for preparing a supported catalyst, characterized by, The method comprises the following steps: S1, placing the carrier in an organic acid for acidification treatment, then adding an additive precursor solution for mixing, and then adding a precipitant for mixing to obtain a composite carrier; S2, immersing the composite carrier in an active component salt solution, and finally performing filtration, washing, drying and calcination to obtain a supported catalyst.

2. The method of claim 1, wherein: The carrier is one of Al2O3, ZSM-5, [B]-MFI, MCM-41, TS, MOR, SBA-15, MCM-48 and KIT-6; and the organic acid is one of maleic acid, citric acid, lactic acid, acetic acid, succinic acid, benzoic acid and dodecylbenzenesulfonic acid.

3. The method of claim 1, wherein: The additive is one of manganese dioxide, chromium trioxide, nickel oxide, zinc oxide, magnesium oxide and cerium dioxide.

4. The method of claim 1, wherein: The additive precursor solution is a nitrate solution of the additive.

5. The method of claim 1, wherein: The precipitant is one of sodium carbonate, sodium hydroxide, potassium carbonate and potassium hydroxide; and the molar ratio of the additive to the precipitant is 1:0.5-5.

6. The method of any one of claims 1 to 5, wherein: The active component is copper oxide; and the active component salt solution is one of copper nitrate, copper sulfate, copper carbonate and copper acetate.

7. The method of claim 5, wherein: The mass concentration of the active component salt solution is 10-50%wt.

8. The method of claim 1, wherein: The mass ratio of the carrier, the additive and the active component is (1-30):(10-50):(30-60).

9. Use of the catalyst prepared by the method of any one of claims 1-8 as a catalyst for preparing hexanediol by hydrogenating dimethyl adipate.

10. Use according to claim 9, characterized in that: In the preparation of hexanediol by hydrogenation of dimethyl adipate, the dimethyl adipate concentration is 5-60%, the solvent is methanol, the space velocity is 0.1-1.0h -1 , the reaction pressure is 4-9MPA, the reaction time is 1-5h, the reaction temperature is 170-250℃, and the hydrogen-ester ratio is 100-700:1.

Images