A process for the condensation of cyclopentanone with aldehydes and catalysts used

Abstract

The application discloses a condensation method of cyclopentanone and aldehyde and a catalyst used in the method. The condensation method uses cyclopentanone and aldehyde as raw materials, and performs a condensation reaction in the presence of a catalyst. The catalyst is a supported catalyst, and is prepared by in-situ growth of hydrotalcite on a solid acid carrier and calcination. The solid acid carrier has a macroporous or mesoporous structure. Preferably, the solid acid carrier is selected from metal oxides or modified molecular sieves. The condensation method has the advantages of obvious increase of reaction selectivity and reaction yield of a target product, acceleration of the condensation reaction rate, one-step reaction of the condensation method, no use of a large amount of acid and alkali, and simple post-treatment.

Description

Technical Field

[0001] This invention relates to a condensation method of cyclopentanone and aldehyde and the catalyst used therein. Background Technology

[0002] Cyclopentanone condenses with aldehydes, followed by hydrogenation and oxidative ring expansion to prepare a series of butyl lactones. butyl lactones possess a strong and persistent creamy aroma and are important raw materials for flavoring milk and cream, as well as being widely used in blending coconut, strawberry, peach, and other flavorings.

[0003] The condensation of cyclopentanone with an aldehyde can be divided into two steps: 1) cyclopentanone reacts with the aldehyde under alkaline conditions to form an intermediate; 2) the intermediate is dehydrated under acidic conditions to form the product. Industrially, the first step of the condensation reaction is often catalyzed by an aqueous sodium hydroxide solution, while the second step of the dehydration reaction is often catalyzed by organic acids such as oxalic acid. However, the extensive use of acids and alkalis makes post-reaction processing cumbersome, and residual acids or alkalis can also lead to product polymerization, reducing the reaction yield.

[0004] Taking the condensation of cyclopentanone and n-pentanal as an example, previous studies have shown that base-catalyzed condensation reactions typically involve the base first combining with the α-H atom in cyclopentanone to form an enol anion. This enol anion acts as a nucleophile, attacking the positively charged carbonyl carbon atom of n-pentanal, resulting in an addition reaction to generate the intermediate 2-(1-hydroxypentyl)cyclopentanone. The 2-(1-hydroxypentyl)cyclopentanone then undergoes dehydration under acidic conditions to yield the target product, 2-pentylcyclopentanone. The reaction mechanism is as follows:

[0005]

[0006] Because cyclopentanone, n-pentanal, and the generated 2-(1-hydroxypentyl)cyclopentanone intermediate and 2-pentylcyclopentanone target product all possess reactive α-H and carbonyl groups, they can undergo both aldehyde-ketone cross-condensation and aldehyde-ketone self-condensation, leading to a significant reduction in the selectivity of the reaction and making it difficult to achieve a high level of selectivity. In particular, as the reaction proceeds, the concentrations of the 2-(1-hydroxypentyl)cyclopentanone intermediate and the 2-pentylcyclopentanone target product continuously increase. These two products readily condense with n-pentanal or cyclopentanone starting materials, and this byproduct accounts for approximately 80% of the total byproducts. Furthermore, the longer the reaction time, the more pronounced this side reaction becomes. Based on the above-mentioned formation mechanism of the target product 2-pentylcyclopentanone, it is known that the reaction requires both acid and base catalysis. Therefore, in the prior art, the reaction needs to be carried out in two steps. However, the reaction process between cyclopentanone and n-pentanal is a reversible reaction. Carrying the reaction in two steps is not conducive to the forward reaction, resulting in a decrease in the reaction rate. This, in turn, increases the residence time of reactants, intermediates and products in the reaction system, which easily leads to side reactions. Summary of the Invention

[0007] To address the shortcomings and deficiencies of existing technologies, this invention provides an improved condensation method for cyclopentanone and aldehydes. This condensation method significantly improves the reaction selectivity and yield of the target product, accelerates the condensation reaction rate, requires only one step, does not involve the use of large amounts of acids or bases, and simplifies post-processing.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A condensation method for cyclopentanone and aldehyde, wherein the condensation method uses cyclopentanone and aldehyde as raw materials and carries out the condensation reaction in the presence of a catalyst; the catalyst is a supported catalyst and is prepared by in-situ growth of hydrotalcite on a solid acid support and calcination; the solid acid support has a macroporous or mesoporous structure.

[0010] In this invention, macropores refer to pores with a diameter greater than 50 nm, and mesopores refer to pores with a diameter of 2-50 nm, also known as medium pores.

[0011] Through research, the inventors discovered that solid acid supports with macroporous or mesoporous structures possess well-developed pore structures. These well-developed pore structures facilitate the diffusion of intermediates and the final target product generated during the condensation of cyclopentanone and aldehydes, significantly shortening their residence time in the reaction system and suppressing side reactions. By in-situ growing hydrotalcite on the solid acid support, a layered hydrotalcite structure can be obtained. After calcination, the hydrotalcite generates a corresponding metal oxide on the solid acid support. This metal oxide retains the layered structure of the hydrotalcite and remains supported on the well-developed pore structure of the solid acid support. This results in a catalyst with dual acid-base functionality, and the close proximity of the acid and base catalytic sites allows for simultaneous and synergistic acid-base catalysis. Because the catalyst of this invention is dual-functional and both the support and the active ingredient possess specific structures, the condensation reaction of cyclopentanone and aldehydes can be carried out in a single step, avoiding the drawbacks of the two-step reaction methods used in existing technologies.

[0012] In some embodiments, the solid acid support is selected from metal oxides or modified molecular sieves; the metal oxide is selected from one or more combinations of TiO2, CeO2, ZrO2, MoO3, and Nb2O3; the modified molecular sieve is a molecular sieve that has undergone acid treatment and alkali treatment; the molecular sieve is selected from one or more combinations of ZSM-5 molecular sieve, Y-type molecular sieve, Beta molecular sieve, SBA-15 molecular sieve, TS-1 molecular sieve, and Ti-MWW molecular sieve.

[0013] In some embodiments, the metal oxide is prepared by a method comprising the following steps: mixing and reacting a compound of the corresponding metal element, a surfactant, a coordinating agent, phosphoric acid, and a solvent to obtain a precursor; removing the solvent from the precursor; and calcining to obtain the metal oxide. The surfactant acts as a structure-directing agent, the coordinating agent coordinates with the compound of the corresponding metal element (metal precursor), and the phosphoric acid acts as a catalyst to promote the synergistic assembly of the coordinated metal precursor and the surfactant. Calcination yields an acidic metal oxide support with a macroporous or mesoporous structure.

[0014] In some embodiments, the metal oxide is TiO2, and the compound of the corresponding metal element is selected from one or more combinations of titanium tert-butoxide, titanium methoxy, tetrabutyl titanate, isopropyl titanate, tetraethyl titanate, and titanium acetylacetonate.

[0015] In some embodiments, the metal oxide is CeO2, and the compound of the corresponding metal element is selected from one or more combinations of cerium propionate, cerium acetate, cerium nitrate, and cerium tert-butoxide.

[0016] In some embodiments, the metal oxide is ZrO2, and the compound of the corresponding metal element is selected from one or more combinations of zirconium propionate, zirconium acetate, zirconium nitrate, zirconium oxynitrate, zirconium ethoxy, zirconium tert-butoxide, and zirconium n-butoxide.

[0017] In some embodiments, the metal oxide is MoO3, and the compound of the corresponding metal element is selected from one or more combinations of molybdenum acetate, ammonium molybdate, molybdenum acetylacetonate, and ammonium phosphomolybdate.

[0018] In some embodiments, the metal oxide is Nb₂O₃, and the compound of the corresponding metal element is selected from one or more combinations of niobium oxalate, niobium ethoxylate, and ammonium oxalate hydrate.

[0019] In some embodiments, the surfactant is a nonionic surfactant and is selected from one or more combinations of polyethylene oxide-polypropylene oxide diblock copolymer, polyethylene oxide-polybutane diblock copolymer, polyethylene oxide-polystyrene diblock copolymer, polyethylene oxide-polymethyl methacrylate diblock copolymer, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and polyethylene oxide-polypropylene oxide-polypropylene oxide triblock copolymer.

[0020] In some embodiments, the ligand is selected from one or more combinations of citric acid, acetylacetone, and ethylenediaminetetraacetic acid.

[0021] In some embodiments, the solvent is selected from one or more combinations of ethanol, methanol, isopropanol, butanol, and water.

[0022] In some embodiments, the molar ratio of the corresponding metal element compound, surfactant, ligand, and phosphoric acid is 1:0.1 to 10:3 to 100:0.1 to 5.

[0023] In some embodiments, the reaction temperature in the preparation method of the metal oxide is 20–80°C.

[0024] In some embodiments, the calcination temperature in the preparation method of the metal oxide is 300–800°C.

[0025] In some embodiments, in the method for preparing the metal oxide, the reaction time is 0.5 to 24 hours, and the calcination time is 0.5 to 24 hours.

[0026] In some embodiments, the acid is selected from one or more combinations of oxalic acid, boric acid, acetic acid, and propionic acid.

[0027] In some embodiments, the base is selected from one or more combinations of sodium hydroxide, sodium carbonate, ethylenediamine, triethylamine, n-butylamine, piperidine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

[0028] In some embodiments, the modified molecular sieve is prepared by a preparation method including the following steps: 1) acid treatment of the molecular sieve with an acid solution, followed by washing, drying, and calcination to obtain the acid-treated molecular sieve; 2) alkali treatment of the acid-treated molecular sieve with an alkaline solution, followed by washing, drying, and calcination to obtain the modified molecular sieve.

[0029] In some embodiments, the molar concentration of the acid solution is 0.05 to 5 mol / L.

[0030] In some embodiments, the acid treatment temperature is 30–180°C.

[0031] In some embodiments, the acid treatment time is 0.5 to 48 hours.

[0032] In some embodiments, the molar concentration of the alkaline solution is 0.05 to 5 mol / L.

[0033] In some embodiments, the temperature of the alkali treatment is 30–180°C.

[0034] In some embodiments, the alkali treatment time is 0.5 to 48 hours.

[0035] In some embodiments, the catalyst is prepared by a method comprising the following steps: mixing the solid acid support and water to obtain a mixture, adding an alkaline solution and a metal salt solution dropwise to the mixture to carry out a precipitation reaction, and aging, washing, and drying to obtain the catalyst.

[0036] In some embodiments, the alkaline solution is a mixed solution of sodium hydroxide and sodium carbonate.

[0037] In some embodiments, the concentration of sodium hydroxide in the alkaline solution is 0.01–5.0 mol / L, and the concentration of sodium carbonate is 0.01–5.0 mol / L.

[0038] In some embodiments, the metal salt solution is a mixed solution of aluminum nitrate and a divalent metal nitrate, wherein the divalent metal nitrate is selected from one or more combinations of Mg(NO3)2, Ca(NO3)2, Ba(NO3)2, Co(NO3)2, Mn(NO3)2, and Zn(NO3)2.

[0039] In some embodiments, the concentration of aluminum nitrate in the metal salt solution is 0.1–3.0 mol / L, and the concentration of divalent metal nitrate is 0.1–5.0 mol / L.

[0040] In some embodiments, the precipitation reaction is carried out at a temperature of 30–90°C.

[0041] In some embodiments, the precipitation reaction takes 0.5 to 48 hours.

[0042] In some embodiments, the precipitation reaction is carried out at a pH of 8 to 11.

[0043] In some embodiments, the aging temperature is 30–90°C.

[0044] In some embodiments, the aging time is 0.5 to 48 hours.

[0045] In some embodiments, the catalyst contains 10%-90% solid acid support by weight percentage.

[0046] In some embodiments, the calcination temperature in the catalyst preparation method is 350–700°C.

[0047] In some embodiments, the calcination time in the catalyst preparation method is 0.5 to 24 hours.

[0048] In some embodiments, the aldehyde is selected from one or more combinations of pentanal, hexanal, heptal, octanal, nonanal, and decanal.

[0049] In some embodiments, the condensation reaction of cyclopentanone with aldehyde is a batch reaction carried out in a reaction vessel.

[0050] In some embodiments, the temperature of the condensation reaction in the intermittent reaction is 50–200°C.

[0051] In some embodiments, the pressure of the condensation reaction in the intermittent reaction is 0.1 MPa to 1 MPa.

[0052] In some embodiments, the condensation reaction takes 0.5 to 12 hours in the intermittent reaction.

[0053] In some embodiments, the molar ratio of cyclopentanone to aldehyde in the intermittent reaction is 3:1 to 6.

[0054] In some embodiments, the condensation reaction of cyclopentanone with aldehyde is a continuous reaction carried out in a fixed bed.

[0055] In some embodiments, the temperature of the condensation reaction in the continuous reaction is 100–300°C.

[0056] In some embodiments, the pressure of the condensation reaction in the continuous reaction is 0.1 MPa to 1 MPa.

[0057] In some embodiments, in the continuous reaction, the mass hourly space velocity (HHSV) of the cyclopentanone is 0.3–5 h⁻¹. -1 .

[0058] In some embodiments, the molar ratio of cyclopentanone to aldehyde in the intermittent reaction is 3:1 to 6.

[0059] The present invention also provides the aforementioned catalyst. This catalyst is a bifunctional acid-base catalyst, and when used to catalyze the condensation reaction of cyclopentanone and aldehyde, it can significantly improve the reaction selectivity and reaction yield of the target product, while also increasing the condensation reaction rate.

[0060] The present invention also provides a method for preparing the aforementioned catalyst, the method comprising the steps of in-situ growth of hydrotalcite on a solid acid support and calcination to obtain the catalyst.

[0061] In some embodiments, the preparation method includes the following steps: mixing the solid acid support and water to obtain a mixture, adding an alkaline solution and a metal salt solution dropwise to the mixture to carry out a precipitation reaction, and aging, washing, and drying to obtain the catalyst.

[0062] In some embodiments, the solid acid support is selected from metal oxides or modified molecular sieves; the metal oxide is selected from one or more combinations of TiO2, CeO2, ZrO2, MoO3, and Nb2O3; the modified molecular sieve is a molecular sieve that has undergone acid treatment and alkali treatment; the molecular sieve is selected from one or more combinations of ZSM-5 molecular sieve, Y-type molecular sieve, Beta molecular sieve, SBA-15 molecular sieve, TS-1 molecular sieve, and Ti-MWW molecular sieve.

[0063] In some embodiments, the preparation method further includes mixing and reacting a compound of the corresponding metal element, a surfactant, a ligand, phosphoric acid, and a solvent to obtain a precursor, removing the solvent from the precursor, and calcining to obtain the metal oxide.

[0064] In some embodiments, the preparation method further includes the steps of acid treatment of the molecular sieve with an acid solution, followed by washing, drying, and calcination to obtain the acid-treated molecular sieve; and alkali treatment of the acid-treated molecular sieve with an alkaline solution, followed by washing, drying, and calcination to obtain the modified molecular sieve.

[0065] Compared with the prior art, the present invention has the following advantages:

[0066] This invention uses a solid acid support with a macroporous or mesoporous structure as a catalyst support. This support possesses a well-developed pore structure, which facilitates the diffusion of the intermediate and the final target product generated during the condensation of cyclopentanone and aldehyde. The residence time of both products in the reaction system is significantly shortened, and side reactions are significantly suppressed. Therefore, the condensation method of this invention can significantly improve the reaction selectivity and yield of the target product, while also accelerating the condensation reaction rate.

[0067] This invention obtains layered hydrotalcite supported on a solid acid support by in-situ growth of hydrotalcite. After calcination, the hydrotalcite generates corresponding metal oxides on the solid acid support. These metal oxides retain the layered structure of the hydrotalcite and are still supported on the solid acid support with its well-developed pore structure. Therefore, the catalyst of this invention has dual acid and base functions, and the acid and base catalytic sites in the catalyst are close to each other, enabling simultaneous and synergistic acid and base catalysis.

[0068] In the catalyst of this invention, the solid base active component obtained after calcining hydrotalcite is uniformly distributed on the surface of the solid acid support, with the acid and base catalytic sites close together. The base sites activate the α-H on cyclopentanone, effectively initiating the condensation reaction and promoting the formation of intermediates. Meanwhile, the nearby acid sites facilitate the rapid dehydration of the intermediates, generating the final target product of the condensation reaction. Therefore, the condensation reaction of this invention has a fast reaction rate.

[0069] The catalyst of this invention is bifunctional (both acid and base) and both the support and the active ingredient have specific structures. Therefore, the condensation reaction of cyclopentanone and aldehyde can be carried out in one step, avoiding the defects of increased side reactions caused by the two-step reaction of acid catalysis and base catalysis in the prior art. It can also avoid the use of large amounts of acid and base, and the post-processing is simple and highly environmentally friendly. Attached Figure Description

[0070] Figure 1 This is the X-ray diffraction pattern of the CoMgAl-LDH / TiO2 catalyst prepared in Example 1;

[0071] Figure 2 The pore size distribution diagram is shown in Example 1 for the CoMgAl-LDH / TiO2 catalyst prepared in Example 1.

[0072] Figure 3 The figure shows the stability test results of the CoMgAl-LDH / TiO2 catalyst prepared in Example 1. Detailed Implementation

[0073] The present invention will be further described below with reference to embodiments. However, the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific applications, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0074] Preparation Example 1

[0075] This preparation example provides a supported catalyst, which is prepared by the following method:

[0076] 1) Add 340g tetrabutyl titanate, 2kg ethanol, and 400g acetylacetone to the reactor and stir at 50°C for 2h. Then add 120g polyethylene oxide-polypropylene oxide diblock copolymer and 12g phosphoric acid and continue stirring for 6h.

[0077] 2) Remove the solvent ethanol from the mixed solution obtained in step 1) in a distillation column, and then transfer it to an 80℃ constant temperature drying oven to dry for 24 hours; calcine the dried sample at 500℃ for 4 hours to obtain the TiO2 support.

[0078] 3) Add 200g of the TiO2 support obtained in step 2) and 200g of water to a 2L reactor, start stirring and heat to 80℃; after the temperature stabilizes, add 600mL of salt solution (0.3mol / L aluminum nitrate, 0.6mol / L magnesium nitrate, 0.05mol / L cobalt nitrate) and alkaline solution (0.2mol / L sodium carbonate, 0.3mol / L sodium hydroxide) dropwise, maintaining the pH of the system between 8 and 11, for about 6 hours; after the dropwise addition is completed, maintain the temperature at 80℃ and continue aging for 6 hours; after aging, wash with distilled water and dry in an 80℃ constant temperature drying oven for 24 hours; calcine the dried sample at 550℃ for 6 hours to obtain the TiO2-supported aluminum cobalt magnesium hydrotalcite calcination catalyst, denoted as CoMgAl-LDH / TiO2 catalyst. Here, LDH refers to hydrotalcite.

[0079] Figure 1 and Figure 2 The X-ray diffraction pattern and pore size distribution of the CoMgAl-LDH / TiO2 catalyst prepared in Example 1 are shown below. Figure 1 The X-ray diffraction patterns confirmed the successful synthesis of the TiO2 support and the CoMgAl-LDH / TiO2 catalyst. Figure 2 It can be seen that the CoMgAl-LDH / TiO2 catalyst has obvious mesoporous and macroporous structures.

[0080] According to the temperature-programmed desorption of ammonia and carbon dioxide, the number of acidic sites in the CoMgAl-LDH / TiO2 catalyst prepared in this example was 56.4 mmol / g and the number of basic sites was 291.2 mmol / g.

[0081] Preparation Example 2

[0082] This preparation example provides several catalysts, the preparation methods of which are basically the same as those in Preparation Example 1, the only difference being that the tetrabutyl titanate in step 1) is replaced with cerium tert-butoxide, zirconium tert-butoxide, molybdenum acetylacetonate, and niobium ethoxylate, respectively. The finally obtained supported catalysts are denoted as CoMgAl-LDH / ZrO2, CoMgAl-LDH / CeO2, CoMgAl-LDH / MoO3, and CoMgAl-LDH / Nb2O3, respectively.

[0083] Preparation Example 3

[0084] This preparation example provides several catalysts, the preparation methods of which are basically the same as those in Preparation Example 1, the only difference being that magnesium nitrate and cobalt nitrate in step 1) are replaced with other nitrates. The finally obtained supported catalysts are denoted as MgAl-LDH / TiO2 (other nitrates are magnesium nitrate 0.6 mol / L), CoAl-LDH / TiO2 (other nitrates are cobalt nitrate 0.6 mol / L), CaMnAl-LDH / TiO2 (other nitrates are calcium nitrate 0.6 mol / L, manganese nitrate 0.05 mol / L), CoBaAl-LDH / TiO2 (other nitrates are cobalt nitrate 0.05 mol / L, barium nitrate 0.6 mol / L), CoZnAl-LDH / TiO2 (other nitrates are cobalt nitrate 0.05 mol / L, zinc nitrate 0.6 mol / L), and ZnAl-LDH (other nitrates are zinc nitrate 0.6 mol / L) / TiO2.

[0085] Preparation Example 4

[0086] 1) Weigh 200.0g of Beta molecular sieve (molar ratio of silica to alumina is 30) and 1000g of deionized water into a three-necked flask equipped with a reflux condenser and a stirrer. Add 200mL of 0.05mol / L oxalic acid solution, stir thoroughly, and heat to 90℃ for 5h. Remove the mixture, filter, and wash with water until pH≈7. Dry the filter cake in an 80℃ oven and calcine it in a muffle furnace at 550℃ for 6h under air atmosphere to obtain acid-treated Beta molecular sieve.

[0087] 2) Add 1000 deionized water and 0.01 mol piperidine to the acid-treated Beta molecular sieve, stir thoroughly and heat to 85℃ for 12 h, then remove, filter, and wash with water until pH≈7; place the filter cake in an 80℃ oven to dry and calcine in a muffle furnace at 550℃ in air atmosphere for 6 h to obtain the acid-base treated Beta molecular sieve.

[0088] 3) Add the acid-base treated Beta molecular sieve obtained in step 2) and 200g of water to a 2L reactor, start stirring and heat to 80℃; after the temperature stabilizes, add 600mL of salt solution (0.3mol / L aluminum nitrate, 0.6mol / L magnesium nitrate, 0.05mol / L cobalt nitrate) and alkaline solution (0.2mol / L sodium carbonate, 0.3mol / L sodium hydroxide) dropwise, maintaining the pH of the system between 8 and 11, for about 6 hours; after the dropwise addition is completed, maintain the temperature at 80℃ and continue aging for 6 hours; after aging, wash with distilled water and dry in an 80℃ constant temperature drying oven for 24 hours; calcine the dried sample at 550℃ for 6 hours to obtain the CoMgAl-LDH / Beta catalyst.

[0089] Preparation Example 5

[0090] This preparation example provides several catalysts, and their preparation methods are basically the same as those in Preparation Example 4, except that the Beta molecular sieve in step 1) is replaced with ZSM-5 molecular sieve, Y-type molecular sieve, SBA-15 molecular sieve, TS-1 molecular sieve, and Ti-MWW molecular sieve, respectively. The finally obtained supported catalysts are denoted as CoMgAl-LDH / ZSM-5, CoMgAl-LDH / Y, CoMgAl-LDH / SBA-15, CoMgAl-LDH / TS-1, and CoMgAl-LDH / Ti-MWW, respectively.

[0091] Comparative Preparation Example 1

[0092] This comparative preparation example provides a comparative catalyst, the preparation method of which is as follows:

[0093] 200g of commercial TiO2 support (Aladdin Biochemical Technology Co., Ltd., model T105418; the main pore structure is microporous, i.e., pores with a diameter of less than 2nm) and 200g of water were added to a 2L reactor, and the mixture was stirred and heated to 80℃. After the temperature stabilized, 600mL of salt solution (0.3mol / L aluminum nitrate, 0.6mol / L magnesium nitrate, 0.05mol / L cobalt nitrate) and alkaline solution (0.2mol / L sodium carbonate, 0.3mol / L sodium hydroxide) were added dropwise in parallel, maintaining the pH of the system between 8 and 11, and the addition time was about 6 hours. After the addition was completed, the temperature was maintained at 80℃ and the aging was continued for 6 hours. After aging, the sample was washed with distilled water and dried in a constant temperature drying oven at 80℃ for 24 hours. The dried sample was then calcined at 550℃ for 6 hours to obtain the CoMgAl-LDH / TiO2-commercial catalyst.

[0094] Comparative Preparation Example 2

[0095] This comparative preparation example provides a comparative catalyst, the preparation method of which is as follows:

[0096] 200g of untreated Beta molecular sieve (molar ratio of silica to alumina of 30) and 200g of water were weighed and added to a 2L reactor. The mixture was stirred and heated to 80℃. After the temperature stabilized, 600mL of salt solution (0.3mol / L aluminum nitrate, 0.6mol / L magnesium nitrate, and 0.05mol / L cobalt nitrate) and alkaline solution (0.2mol / L sodium carbonate and 0.3mol / L sodium hydroxide) were added dropwise in parallel, maintaining the pH of the system between 8 and 11 for about 6 hours. After the addition was completed, the temperature was maintained at 80℃ and the aging process continued for 6 hours. After aging, the sample was washed with distilled water and dried in a constant temperature drying oven at 80℃ for 24 hours. The dried sample was then calcined at 550℃ for 6 hours to obtain the CoMgAl-LDH / Beta-untreated catalyst.

[0097] Comparative preparation example 3

[0098] This comparative preparation example provides a comparative catalyst, the preparation method of which is as follows:

[0099] Weigh 400g of water and add it to a 2L reactor. Start stirring and heat to 80℃. After the temperature stabilizes, add 600mL of salt solution (0.3mol / L aluminum nitrate, 0.6mol / L magnesium nitrate, 0.05mol / L cobalt nitrate) and alkaline solution (0.2mol / L sodium carbonate, 0.3mol / L sodium hydroxide) dropwise in parallel, maintaining the pH of the system between 8 and 11. The dropwise addition takes about 6 hours. After the dropwise addition is completed, maintain the temperature at 80℃ and continue aging for 6 hours. After aging, wash with distilled water and dry in an 80℃ constant temperature drying oven for 24 hours. Calcine the dried sample at 550℃ for 6 hours to obtain the CoMgAl-LDH catalyst.

[0100] Example 1

[0101] Under a nitrogen atmosphere, 505 g of cyclopentanone and 40 g of the CoMgAl-LDH / TiO2 catalyst prepared in Example 1 were added to a reaction vessel, and the mixture was stirred and heated to 120 °C. Subsequently, 430 g of n-pentanal was added dropwise over 6 h, followed by a 2 h holding time. The catalyst was separated from the reaction solution by filtration. Quantitative analysis of the reaction solution was performed on an Agilent 7890 gas chromatograph using an HP-INNOWax column and an FID detector. The results were expressed as weight percentages.

[0102] In this application example, n-pentanal can be replaced with other long-chain aldehydes, and the molar ratio of cyclopentanone to long-chain aldehydes is controlled at 1.2. The detection results are shown in Table 1 below. As can be seen from Table 1, the CoMgAl-LDH / TiO2 catalyst can catalyze the condensation reaction of cyclopentanone with various long-chain aldehydes well, and the activity decreases slightly with the increase of carbon chain length.

[0103] Table 1. Crude product content results

[0104]

[0105] In this application example, different catalysts in Preparation Example 2 were evaluated by changing the catalyst. The test results are shown in Table 2 below. As can be seen from Table 2, when TiO2, CeO2, ZrO2, MoO3, and Nb2O3 were used as supports, the catalysts could all catalyze the condensation of cyclopentanone and n-pentanal. Among them, when Nb2O3 was used as a support, the content of n-pentanal in the crude product was only 0.5%, and the content in the product was 80.2%.

[0106] Table 2 Results of crude product content

[0107]

[0108] In this application example, different catalysts in Preparation Example 3 were evaluated by changing the catalyst. The test results are shown in Table 3 below. As can be seen from Table 3, the acid-base bifunctional catalysts with different active components can all catalyze the condensation of cyclopentanone and n-pentanal. Among them, the component after CaMnAl-LDH calcination was used as the active component, which had the best yield. The n-pentanal content in the crude product was only 0.5%, and the product content was 81.1%.

[0109] Table 3 Results of crude product content

[0110]

[0111]

[0112] In this application example, different catalysts in Preparation Example 4 and Preparation Example 5 were evaluated by changing the catalyst. The test results are shown in Table 4 below. As can be seen from Table 4, the acid-base bifunctional catalysts using various molecular sieves treated with acid and base as supports all exhibit excellent condensation performance of cyclopentanone and n-pentanal. Among them, the acid-base treated Beta as support has the best yield, with n-pentanal content of 0.8% in the crude product and 78.9% in the finished product.

[0113] Table 4 Results of crude product content

[0114]

[0115] Table 5 shows the performance of the acid-base bifunctional catalyst CoMgAl-LDH / TiO2 prepared by the TiO2 support in step 2) of Preparation Example 1 and the acid-base bifunctional catalyst CoMgAl-LDH / Beta prepared by step 3) in Preparation Example 4. It also compares the performance of the catalyst CoMgAl-LDH / TiO2-commercial prepared using commercial TiO2 as the support in Preparation Example 1, the catalyst CoMgAl-LDH / Beta-untreated prepared using untreated Beta molecular sieve as the support in Preparation Example 2, and the performance of the acid-free support-free catalyst CoMgAl-LDH prepared in Preparation Example 3 in the condensation reaction of cyclopentanone and n-pentanal. When only acidic support TiO2 and acid-base treated Beta molecular sieve are used, the crude product contains higher levels of n-pentanal and cyclopentanone, and lower levels of the target product. This indicates that acidic support TiO2 and acid-base treated Beta molecular sieve can catalyze the condensation of cyclopentanone and n-pentanal, but the reaction efficiency is low. When no acidic support is used, and water-based CoMgAl-LDH is directly used as the catalyst, the crude product contains as much as 19.7% n-pentanal and 45.6% cyclopentanone, while the product content is only 15.8%. This is because the CoMgAl-LDH catalyst has a large number of basic sites and a small number of acidic sites. However, when using commercially available TiO2 as the support, the product content in the crude product is significantly lower than that of the catalyst with a mesoporous-macroporous structure using TiO2 as the support in Preparation Example 1. Similarly, when using untreated Beta molecular sieves as the support, the product content in the crude product is significantly lower than that of the catalyst using acid-treated mesoporous-macroporous Beta molecular sieves as the support. These results demonstrate that the specific acid-base bifunctional catalyst used in this invention can effectively match the reaction between cyclopentanone and aldehydes, resulting in a fast reaction rate. Furthermore, its well-developed pore structure can effectively suppress side reactions, thereby improving product yield.

[0116] Table 5 Results of crude product content

[0117]

[0118] Example 2

[0119] The CoMgAl-LDH / TiO2 catalyst prepared in Example 1 was investigated in a fixed-bed reactor for the continuous condensation reaction of cyclopentanone and n-pentanal. Reaction conditions: reaction temperature 140℃, reaction pressure 1 MPa, and mass hourly space velocity (WHSV) of cyclopentanone 1 h⁻¹. -1 The molar ratio of cyclopentanone to n-pentanal was 1.2. Quantitative analysis of the products after the reaction was performed on an Agilent 7890 gas chromatograph using an HP-INNOWax column and an FID detector.

[0120] Figure 3The reaction performance of cyclopentanone and n-pentanal with the CoMgAl-LDH / TiO2 catalyst is evaluated. Figure 3 It can be seen that the crude product contains about 1% n-pentanal, about 20% cyclopentanone, and about 78% product content. Moreover, no signs of inactivation were observed during the 200-hour reaction process, demonstrating excellent reactivity and stability.

[0121] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0122] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A method for the condensation of cyclopentanone and aldehyde, characterized in that: The condensation method uses cyclopentanone and aldehyde as raw materials to carry out a condensation reaction in the presence of a catalyst; the catalyst is a supported catalyst and is prepared by in-situ growth of hydrotalcite on a solid acid support and calcination; the solid acid support has a macroporous or mesoporous structure. The solid acid support is selected from metal oxides or modified molecular sieves; The metal oxide is selected from one or more combinations of TiO2, CeO2, ZrO2, MoO3, and Nb2O3; the metal oxide is prepared by a method including the following steps: mixing and reacting a compound of the corresponding metal element, a surfactant, a coordinating agent, phosphoric acid, and a solvent to obtain a precursor, removing the solvent from the precursor, and calcining to obtain the metal oxide; the modified molecular sieve is a molecular sieve that has undergone acid treatment and alkali treatment; the molecular sieve is selected from one or more combinations of ZSM-5 molecular sieve, Y-type molecular sieve, Beta molecular sieve, SBA-15 molecular sieve, TS-1 molecular sieve, and Ti-MWW molecular sieve.

2. The condensation method of cyclopentanone and aldehyde according to claim 1, characterized in that: The metal oxide is TiO2, and the compound of the corresponding metal element is selected from one or more combinations of titanium tert-butoxide, titanium methoxy, tetrabutyl titanate, isopropyl titanate, tetraethyl titanate, and titanium acetylacetonate.

3. The condensation method of cyclopentanone and aldehyde according to claim 1, characterized in that: The metal oxide is CeO2, and the compound of the corresponding metal element is selected from one or more combinations of cerium propionate, cerium acetate, cerium nitrate, and cerium tert-butoxide; or, the metal oxide is ZrO2, and the compound of the corresponding metal element is selected from one or more combinations of zirconium propionate, zirconium acetate, zirconium nitrate, zirconium oxynitrate, zirconium ethoxy, zirconium tert-butoxide, and zirconium n-butoxide.

4. The condensation method of cyclopentanone and aldehyde according to claim 1, characterized in that: The metal oxide is MoO3, and the compound of the corresponding metal element is selected from one or more combinations of molybdenum acetate, ammonium molybdate, molybdenum acetylacetonate, and ammonium phosphomolybdate; or, the metal oxide is Nb2O3, and the compound of the corresponding metal element is selected from one or more combinations of niobium oxalate, niobium ethoxylate, and ammonium oxalate hydrate.

5. The condensation method of cyclopentanone and aldehyde according to claim 1, characterized in that: The surfactant is a nonionic surfactant and is selected from one or more combinations of polyethylene oxide-polypropylene oxide diblock copolymer, polyethylene oxide-polybutane diblock copolymer, polyethylene oxide-polystyrene diblock copolymer, polyethylene oxide-polymethyl methacrylate diblock copolymer, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and polyethylene oxide-polypropylene oxide-polypropylene oxide triblock copolymer; and / or, the ligand is selected from one or more combinations of citric acid, acetylacetone, and ethylenediaminetetraacetic acid; and / or, the solvent is selected from one or more combinations of ethanol, methanol, isopropanol, butanol, and water.

6. The condensation method of cyclopentanone and aldehyde according to claim 1, characterized in that: The molar ratio of the corresponding metal element compound, surfactant, ligand, and phosphoric acid is 1:0.1-10:3-100:0.1-5; and / or, the reaction temperature is 20-80°C, and the calcination temperature is 300-800°C; and / or, the reaction time is 0.5-24h, and the calcination time is 0.5-24h.

7. The condensation method of cyclopentanone and aldehyde according to claim 1, characterized in that: The acid is selected from one or more combinations of oxalic acid, boric acid, acetic acid, and propionic acid; and / or the base is selected from one or more combinations of sodium hydroxide, sodium carbonate, ethylenediamine, triethylamine, n-butylamine, piperidine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

8. The condensation method of cyclopentanone and aldehyde according to claim 1, characterized in that: The modified molecular sieve is prepared by a method including the following steps: 1) Acid treatment of the molecular sieve with an acid solution, followed by washing, drying, and calcination to obtain the acid-treated molecular sieve; 2) The acid-treated molecular sieve is subjected to alkali treatment with an alkaline solution, and then washed, dried and calcined to obtain the modified molecular sieve.

9. The condensation method of cyclopentanone and aldehyde according to claim 8, characterized in that: The molar concentration of the acid solution is 0.05–5 mol / L, and the temperature of the acid treatment is 30–180°C; and / or, the time of the acid treatment is 0.5–48 h; and / or, the molar concentration of the alkali solution is 0.05–5 mol / L, and the temperature of the alkali treatment is 30–180°C; and / or, the time of the alkali treatment is 0.5–48 h.

10. The condensation method of cyclopentanone and aldehyde according to claim 1, characterized in that: The catalyst is composed of The catalyst is prepared by a method including the following steps: mixing the solid acid support and water to obtain a mixture, adding an alkaline solution and a metal salt solution dropwise to the mixture to carry out a precipitation reaction, aging, washing, and drying to obtain the catalyst.

11. The condensation method of cyclopentanone and aldehyde according to claim 10, characterized in that: The alkaline solution is a mixed solution of sodium hydroxide and sodium carbonate, wherein the concentration of sodium hydroxide is 0.01–5.0 mol / L and the concentration of sodium carbonate is 0.01–5.0 mol / L; and / or, the metal salt solution is a mixed solution of aluminum nitrate and divalent metal nitrate, wherein the divalent metal nitrate is selected from one or more combinations of Mg(NO3)2, Ca(NO3)2, Ba(NO3)2, Co(NO3)2, Mn(NO3)2, and Zn(NO3)2, wherein the concentration of aluminum nitrate is 0.1–3.0 mol / L and the concentration of divalent metal nitrate is 0.1–5.0 mol / L.

12. The condensation method of cyclopentanone and aldehyde according to claim 1, characterized in that: The catalyst contains 10%-90% solid acid support by weight percentage.

13. The condensation method of cyclopentanone and aldehyde according to claim 1, characterized in that: The roasting temperature is 350–700°C; and / or the roasting time is 0.5–24 h.

14. The condensation method of cyclopentanone and aldehyde according to claim 1, characterized in that: The aldehyde is selected from one or more combinations of pentanal, hexanal, heptal, octanal, nonanal, and decanal.

15. The catalyst according to any one of claims 1-14.

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