A supported metal catalyst for preparing alcohol compounds from carbonyl compounds, its preparation and its application

Abstract

The present invention relates to a supported metal catalyst for the preparation of alcohol compounds by carbonyl hydrogenation, its preparation and application. The catalyst support contains oxides and / or hydroxides of transition metals, and Pt metal nanoparticles are supported on the surface of the catalyst support. Among them, the content of the transition metal accounts for 0.1% - 5 wt% of the total catalyst content, and the content of Pt is 0.01% - 5 wt%; the catalyst support is TiO 2 , SiO 2 , Al 2 O 3 , CeO 2 or at least one of them. The catalyst of the present invention has significantly better results in the reaction of hydrogenating furfural, cinnamaldehyde, and acrolein to prepare the corresponding alcohol compounds than the catalyst prepared by using a support without transition metal modification. The catalyst of the present invention has important application prospects in the reaction of hydrogenating carbonyl compounds to prepare alcohol compounds.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical engineering, and particularly relates to a supported metal catalyst for preparing alcohol compounds from carbonyl compounds, its preparation and its application. Background Art

[0002] Alcohol compounds have important applications in the synthesis of fine chemicals such as pharmaceutical chemicals and pesticides. The selective hydrogenation of C=O substrates is an important method for the preparation of alcohol compounds. Noble metals such as Pt, Pd, Ru, and Rh are commonly used heterogeneous hydrogenation catalysts. However, in order to improve their hydrogenation activity and selectivity for C=O substrates, people usually introduce transition metal additives such as Fe, Sn, Co, Ni, Mo, etc. Transition metal promoters generally form alloys with noble metals through co-precipitation or deposition-precipitation methods. For example, impregnating Pt and Fe precursors on activated carbon and carbon fiber can significantly improve the activity and selectivity of cinnamaldehyde hydrogenation to produce cinnamyl alcohol (Applied Catalysis A: General, 435-436 (2012) 131-140.); heating Fe and Pt precursors with CeO 2 or carbon nanotubes at high temperature can obtain Pt 3 Fe / CeO 2 or Pt 3Fe / C catalysts exhibit excellent C=O hydrogenation activity and selectivity in the hydrogenation reactions of cinnamaldehyde and furfural (Journal of Catalysis, 364 (2018) 192 - 203.; ACS Sustainable Chemistry & Engineering, 8 (2020) 12722 - 12730.); in addition, for FePt / SBA-15, FePt / mesoporous ZSM-5, and FePt / TS-1 prepared by the co-impregnation method in the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, Fe can greatly improve the activity and selectivity of the target product (Journal of Catalysis, 354 (2017) 24 - 36.; Catalysis Science & Technology, 7 (2017) 6112 - 6123.; Journal of Catalysis, 382 (2020) 1 - 12.; Journal of Catalysis, 395 (2021) 375 - 386.). People deposit iron on the surface of supported Pt catalysts by atomic deposition or liquid-phase chemical reduction methods, and the obtained catalysts also have high C=O hydrogenation activity (Applied Catalysis B: Environmental, 231 (2018) 182 - 190.; Applied Catalysis B: Environmental, 218 (2017) 591 - 599.). However, most of the catalysts reported currently are obtained by co-impregnation or co-precipitation methods, and the obtained catalysts need to be further calcined and reduced at high temperatures, resulting in difficult control of the deposition position of Fe and a decrease in catalyst activity. This invention reports a method for preparing supported metal catalysts Pt / M-M’Ox (M = Fe, Co, Ni, Zn, Sn; M’Ox = TiO 2 , SiO 2 , Al 2 O 3 , CeO 2 ) using transition metal-modified oxides as carriers. This preparation method has the characteristics of mild conditions, precise and controllable deposition positions of transition metals, and high activity and high selectivity in the hydrogenation reaction of C=O compounds. SUMMARY OF THE INVENTION

[0003] The purpose of this invention is to provide a supported metal catalyst for the preparation of alcohol compounds from carbonyl compounds, its preparation, and its application. Compared with traditional impregnation methods, the catalyst preparation method of this invention has the advantages of mild conditions and controllable metal deposition positions. To achieve the purpose of this invention, the following technical solutions are proposed:

[0004] One aspect of the present invention relates to a supported metal catalyst for preparing alcohols from carbonyl compounds. The catalyst support contains oxides and / or hydroxides of transition metals, and Pt metal nanoparticles are loaded on the surface of the support. Among them, the content of the transition metal accounts for 0.1%-5 wt% (preferably 0.3%-1.7 wt%) of the total catalyst content, and the content of Pt accounts for 0.01%-5 wt% (preferably 0.4%-0.6 wt%) of the total catalyst content; the catalyst support is TiO 2 、SiO 2 、Al 2 O 3 、CeO 2 at least one of them.

[0005] In a preferred embodiment of the present invention, the transition metal is selected from one or a combination of Fe, Co, Ni, Zn, and Sn; preferably, the transition metal is Fe. By doping the support with oxides and / or hydroxides of Fe, the catalytic activity can be further improved.

[0006] In a preferred embodiment of the present invention, the catalyst support is TiO 2 . By using TiO 2 as the support, the catalytic activity can be significantly improved.

[0007] Another aspect of the present invention also relates to a preparation method of the above catalyst. A two-step synthesis method is adopted. First, the catalyst support is modified with transition metal oxides and / or hydroxides, and then Pt metal nanoparticles are loaded.

[0008] In a preferred embodiment of the present invention, the modification of the catalyst support with transition metal oxides and / or hydroxides means that salts of transition metals are deposited on the surface of the catalyst support by a hydrolysis precipitation method. The hydrolysis precipitation temperature is 80-160 °C, and the drying temperature is 40-120 °C.

[0009] In a preferred embodiment of the present invention, the salts of the transition metals are chlorides and / or nitrates of the transition metals.

[0010] In a preferred embodiment of the present invention, the loading of Pt metal nanoparticles means that Pt nanoparticles are adsorbed and loaded onto the catalyst support through a Pt nanoparticle colloid, without high-temperature calcination and reduction above 150 °C.

[0011] In a preferred embodiment of the present invention, the loading temperature of the Pt nanoparticle colloid is 25-100 °C, and the catalyst support is dispersed in deionized water or ethanol during the preparation process.

[0012] Specifically, the preparation method of the carrier M-M’Ox (M = Fe, Co, Ni, Zn, Sn; M’Ox = TiO 2 , SiO 2 , Al 2 O 3 , CeO 2 ) is as follows:

[0013] (1) Weigh a certain amount of transition metal salt and dissolve it in deionized water to obtain a solution with a concentration of 0.01% - 1%. Disperse 1 g of oxide carrier in 2 ml of the above solution, stir for 30 min, then transfer it to a hydrothermal crystallization kettle and treat it at 80 - 160 °C for 1 - 24 h. Hydrolysis occurs to deposit transition metal oxide or hydroxide on the surface of the carrier.

[0014] (2) Centrifuge the solid sample and dry it at 40 - 100 °C for 4 - 12 h. The transition metal salt precursor can be chlorides, nitrates, sulfates, etc. of Fe, Co, Ni, Zn, Sn.

[0015] Specifically, the preparation method of the Pt / M-M’Ox catalyst of the present invention is as follows:

[0016] (1) Dissolve a certain amount of NaOH, KOH, etc. in ethylene glycol, add a certain amount of Pt salt solution. The Pt salt can be chloride, nitrate, amino complex, etc. After stirring for 30 - 120 min and mixing evenly, under the protection of nitrogen and argon, heat it up to 120 - 180 °C and maintain it for 2 - 4 h. After cooling, transfer it to a sealed bottle for standby.

[0017] (2) Disperse the transition metal-modified carrier in a certain amount of water or ethanol, stir for 30 - 120 min, and add the Pt metal colloid solution with the corresponding loading (0.1 - 5 wt%) to the above dispersion under stirring at room temperature and stir for 1 - 12 h. Centrifuge the solid sample, wash it with a large amount of deionized water or absolute ethanol, and after centrifugal separation, the transition metal-modified supported Pt catalyst is obtained. After drying the catalyst in an inert atmosphere, it can be used for catalytic reaction evaluation.

[0018] Another aspect of the present invention also relates to the application of the above catalyst in the preparation of alcohol compounds from carbonyl compounds; preferably, the carbonyl compound is at least one of furfural, cinnamaldehyde, and / or acrolein.

[0019] Specifically, when the above catalyst is used in the reaction for preparing alcohol compounds by carbonyl hydrogenation, the catalytic reaction can be carried out in a continuous flow fixed bed or an autoclave reactor. When used in a flow fixed bed reactor, the catalyst needs to be preformed. When used in an autoclave reactor, a certain amount of catalyst is added to the reaction solution, hydrogen gas at a certain pressure is charged into the autoclave reactor, and the reaction is carried out at a certain temperature. The reaction products are analyzed by gas chromatography.

[0020] The hydrogen pressure is 0.01 - 10 MPa, preferably 0.1 - 5 MPa;

[0021] The reaction temperature is 10 - 300 °C, preferably 50 - 150 °C;

[0022] The reaction time is 0.01 - 48 h, preferably 0.1 - 10 h;

[0023] The selected solvent is methanol, ethanol, isopropanol or water.

[0024] The catalyst of the present invention has the following advantages:

[0025] 1. The catalyst preparation process does not require high-temperature calcination and reduction above 150 °C, has less environmental impact during the catalyst production process, the transition metal site can be controlled, and the safety is relatively high;

[0026] 2. The metal catalyst is not reduced using high-temperature hydrogen reduction;

[0027] 3. The particle size of Pt is controllable and is uniformly dispersed on the catalyst support;

[0028] 4. After being modified by the transition metal, the C=O hydrogenation activity of the catalyst is increased by an order of magnitude compared with the unmodified catalyst;

[0029] 5. This method has a wide application range. The transition metal modification and Pt loading are carried out in two steps, and the two do not interfere with each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 XRD diffraction pattern of the Pt / Fex-TiO 2 catalyst obtained in Example 1;

[0031] Figure 2 TEM photograph of the Pt / Fex-TiO 2 catalyst obtained in Example 1;

[0032] Figure 3 Typical chromatogram of cinnamaldehyde hydrogenation in Example 7;

[0033] Figure 4 Product distribution diagram of cinnamaldehyde hydrogenation in Example 7;

[0034] Figure 5 It is the typical chromatogram of furfural hydrogenation in Example 8;

[0035] Figure 6 It is the result of furfural hydrogenation in Example 8. Specific implementation mode

[0036] The following implementation examples are used to further illustrate the present invention, but it does not limit the scope of the invention defined by the appended claims.

[0037] Example 1

[0038] Weigh 1.112 g of FeCl 3 .6H 2 O, and prepare an FeCl 3 solution with 20 mL of deionized water; weigh 200 mg of TiO 2 (with an average particle size of 25 nm), disperse it in 15 mL of deionized water, after ultrasonic treatment for 15 min, add 25 - 100 μL of the above-mentioned FeCl 3 solution, stir for 2 h, then transfer it to a 50 mL hydrothermal reactor and hydrolyze at 120 °C for 12 h. Cool to room temperature, centrifuge and wash with deionized water 3 times, and dry in an oven at 60 °C to obtain the Fex-TiO 2 (x is the Fe content, 0.6 wt% or 1.7 wt%) support, where Fe exists in the TiO 2 support in the form of Fe(OH) 2 , FeOOH, or FeOy (y is 3 or 4).

[0039] Dissolve 240 mg of NaOH in 30 mL of ethylene glycol, add 167 mg of H 2 PtCl 6 , stir for 120 min to mix evenly, then under the protection of nitrogen or argon, heat up to 180 °C and maintain for 2 - 4 h. After cooling, transfer it to a sealed bottle for standby.

[0040] Disperse 0.1 g of the Fex-TiO 2 support in 10 mL of deionized water, stir for 30 min, drop in 200 μL of the Pt sol solution (i.e., an ethylene glycol solution containing Pt metal nanoparticles), stir for 12 h, then centrifuge and wash with deionized water 2 times, and dry at 60 °C (for 2 h) to obtain the Pt / Fex-TiO 2 catalyst (x is the Fe content, and the Pt content is 0.5 wt%). Place the catalyst in nitrogen protection for standby.

[0041] Example 2

[0042] This example is basically the same as Example 1, except that Co(NO3 ) 2 The carrier was modified with a solution, and the catalyst was labeled as Pt / Cox-TiO 2 , where x = -0.6 wt%, and Co exists in the form of Co(OH) 2 , CoOOH, or CoOy (y = 0 - 2) on the TiO 2 carrier.

[0043] Example 3

[0044] This example is basically the same as Example 1, except that Sn(Cl) 2 solution was used for carrier modification, and the catalyst was labeled as Pt / Snx-TiO 2 , where x = 0.3 wt%, and Sn exists in the form of Sn(OH) 2 , SnO(OH) 2 , or SnO 2 on the TiO 2 carrier.

[0045] Example 4

[0046] This example is basically the same as Example 1, except that SiO 2 was used for carrier modification, and the catalyst was labeled as Pt / Fex-SiO 2 . Where x = 0.3 wt%, and Fe exists in the form of Fe(OH) 2 , FeOOH, or FeOy (y = 0 - 2) on the SiO 2 carrier.

[0047] Example 5

[0048] This example is basically the same as Example 1, except that CeO 2 (with a particle size of 100 nm) was used for carrier modification, and the catalyst was labeled as Pt / Fex-CeO 2 . Where x = 0.3 wt%, and Fe exists in the form of Fe(OH) 2 , FeOOH, or FeOy (y = 0 - 2) on the CeO 2 carrier.

[0049] Example 6

[0050] This example is basically the same as Example 1, except that Al 2 O 3 (with a particle size of 10 - 1000 nm) was used for carrier modification, and the catalyst was labeled as Pt / Fex-Al 2 O 3 . Where x = 0.3 wt%, and Fe exists in the form of Fe(OH) 2, FeOOH, or exists in the form of FeOy (y = 0 - 2) in Al 2 O 3 support.

[0051] Example 7

[0052] The catalytic activity test was carried out for cinnamaldehyde hydrogenation: About 8 mg of Pt / Fex-TiO 2 catalyst was dispersed in 2 mL of a solvent (volume ratio of isopropanol / water was 9:1), 20 mg of cinnamaldehyde was added, 15 mg of n-undecane was used as an internal standard. The reaction flask was transferred to an autoclave. After replacing with high-pressure hydrogen 6 times, 2 MPa of hydrogen was charged, and the reaction was carried out at 40 °C for 2 h. The products were analyzed by gas chromatography. The typical chromatogram is as Figure 3 shown. The obtained products include cinnamyl alcohol, phenylpropanal, phenylpropanol, etc. ( Figure 4 ), and the conversion rate of cinnamaldehyde and the selectivity of cinnamyl alcohol were calculated according to the correction factor. The reaction results are shown in Table 1. The introduction of Fe can significantly improve the catalytic activity of cinnamaldehyde hydrogenation, from 47% of the Pt / TiO 2 catalyst to 99% of the Pt / Fe-TiO 2 . The selectivity of cinnamyl alcohol also increased significantly, from 34% to 84%. It should be noted that excessive Fe will lead to a decrease in the reaction activity, while the selectivity reaches 95% (Table 1).

[0053] Example 8

[0054] The catalytic activity test was carried out for furfural hydrogenation: 24 mg of Pt / Fex-TiO 2 catalyst was dispersed in 3 mL of an aqueous solution containing 58 mg of furfural. After replacing with high-pressure hydrogen 6 times, 2 MPa of hydrogen was charged, and the reaction was carried out at 40 °C for 4 h. The products were analyzed by gas chromatography. The typical chromatogram is as Figure 5 shown. The obtained product was only furfuryl alcohol, and the conversion rate was calculated by the area normalization method. The reaction results are as Figure 6 shown. Similar to cinnamaldehyde hydrogenation, it can be seen that the conversion rate of furfural first increases and then decreases with the increase of iron content, and the optimal iron content is 0.6%.

[0055] Example 9

[0056] The catalytic activity test was carried out for furfural hydrogenation: 24 mg of the catalysts of Examples 2, 4, 5, and 6 were dispersed in 3 mL of a methanol solution containing 58 mg of furfural. After replacing with high-pressure hydrogen 6 times, 2 MPa of hydrogen was charged, and the reaction was carried out at 40 °C for 4 h. The products were analyzed by gas chromatography. The obtained product was only furfuryl alcohol, and the conversion rate was calculated by the area normalization method. The reaction results are shown in Table 2.

[0057] Table 1 Conversion rate of cinnamaldehyde hydrogenation and product distribution

[0058]

[0059] Among them, 0.5Pt is 0.5 wt% of Pt in the total mass of the catalyst, and Fe0.6 or Fe1.7 is 0.6 wt% or 1.7 wt% of Fe in the total mass of the catalyst.

[0060] Table 2 Hydrogenation reaction performance of different catalysts

[0061]

[0062]

[0063] Among them, 0.5Pt is 0.5 wt% of Pt in the total mass of the catalyst, Co 0.6 or Fe 0.3 is 0.6 wt% or 0.3 wt% of Co or Fe in the total mass of the catalyst.

Claims

1. Use of a supported metal catalyst in the preparation of an alcohol compound from a carbonyl compound, wherein the catalyst is synthesized by a two-step method. First, the catalyst support is modified with a transition metal oxide and / or hydroxide, and then Pt metal nanoparticles are loaded on the surface of the modified support; wherein, The content of the transition metal accounts for 0.6 wt% of the total catalyst content, and the content of Pt accounts for 0.01% - 5 wt% of the total catalyst content; the catalyst carrier is TiO 2 , Al 2 O 3 , CeO 2 or at least one of them; the transition metal is Fe; The modification of the catalyst support with a transition metal oxide and / or hydroxide means that a salt of a transition metal is deposited on the surface of the catalyst support by a hydrolysis precipitation method in a hydrothermal crystallization kettle, the hydrolysis precipitation temperature is 80-160 °C, and the drying temperature is 40-120 °C.

2. The use according to claim 1, characterized in that: The carbonyl compound is at least one of furfural, cinnamaldehyde, and acrolein.

3. The use according to claim 1, characterized in that: The salt of the transition metal is a chloride and / or nitrate of the transition metal.

4. The use according to claim 1, characterized in that: The loading of Pt metal nanoparticles means that Pt nanoparticles are adsorbed and loaded onto the catalyst support through a Pt nanoparticle colloid, without high-temperature calcination and reduction above 150 °C.

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