Synergistic catalyst for catalyzing propylene hydroperoxy epoxidation and preparation method and application thereof

Abstract

The application provides a synergistic catalyst for catalyzing propylene hydroperoxy epoxidation and a preparation method thereof. Based on the process design concept of "synergistic catalysis", two catalysts with specific composition and performance are selected, including a monatomic gold catalyst and a cluster or granular gold catalyst, and the two catalysts are mechanically mixed according to different proportions to obtain the synergistic catalyst. The synergistic catalyst can not only break through the limitation that the Ti site must exist on the traditional supported Au-Ti bifunctional catalyst, reduce the difficulty of catalyst development, but also greatly improve the activity of the propylene hydroxylation reaction, greatly improve the atomic utilization rate and improve the stability of the catalyst. The synergistic catalyst has important significance for developing high-performance and high-stability catalysts required by industry.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of catalysts, and in particular relates to a synergistic catalyst for catalyzing propylene hydroperoxy epoxidation and a preparation method and application thereof. BACKGROUND

[0002] Propylene oxide (PO) is the second largest propylene derivative after polypropylene, and is mainly used for producing polyether polyols, propylene glycol, propylene carbonate and other chemical products. Compared with the traditional chlorohydrination method and co-oxidation method, one-step epoxidation of propylene in a hydrogen-oxygen mixed gas to produce propylene oxide (PO) has the outstanding advantages of simple process, high selectivity, easy separation of products and full utilization of reaction heat, and is an ideal process for PO production.

[0003] Currently, the propylene hydroperoxy epoxidation reaction mainly uses a nanometer gold catalyst loaded on a titanium-containing carrier. The gold catalyst loaded on the titanium-containing carrier is a Au-Ti bifunctional catalyst: the Au site catalyzes the generation of a hydrogen peroxide species from H2 and O2, and then the epoxidation reaction with C3H6 occurs at the Ti site to generate PO. The catalyst needs the joint participation of the Au site and the Ti site to obtain high PO catalytic performance. However, during the reaction, the generated PO will further undergo ring-opening at the Ti site to generate by-products such as acetaldehyde, propionaldehyde and acetone, and the further reaction of the by-products leads to the formation of carbon-containing deposition species, which in turn covers the active sites of the catalyst, resulting in the deactivation of the catalyst. In addition, the change in the properties of the Ti-containing carrier will also affect the properties of the gold loaded thereon, and the characterization of the Ti site is also relatively complex, which brings difficulties to the performance adjustment of the catalyst and the development of high-activity catalysts.

[0004] The propylene epoxidation reaction shows obvious gold particle size effect. Haruta et al. (J. Catal. 2011, 281, 12-20) reported that Au particles with a particle size of 2-5 nm loaded on a titanium-containing carrier are beneficial to the propylene epoxidation reaction. Delgass et al. (J. Catal. 2012, 296, 31-42) found that nanometer gold clusters located in the microporous channels of TS-1 have very active catalytic performance. Zhou et al. (J. Catal. 2014, 317, 99-104) found that in the particle size range of 2-5 nm of nanometer gold particles loaded on a titanium-containing carrier, the PO generation rate is exponentially dependent on the particle size of the nanometer gold particles, and according to the fitting relationship between the nanometer gold particle active site model and the experimental data, it is found that the Corner site is the main active site of the nanometer gold particles. In addition, some studies have shown that only gold with a particle size of about 1 nm can selectively generate PO. It can be seen that the influence of the particle size of gold on the propylene hydroperoxy epoxidation reaction is controversial, and the active gold species that can effectively catalyze the propylene hydroperoxy epoxidation reaction is still unclear.

[0005] Propylene hydrooxygen epoxidation to prepare epoxy propane involves two reaction processes, the process of generating peroxide species from H2 and O2, and the process of epoxidation reaction of propylene with peroxide species. Developing a synergistic catalyst that only involves Au sites and contains different gold active species to catalyze the two reaction processes can effectively improve metal utilization and reduce catalyst development cost, which is of great significance for developing high-performance and high-stability catalysts required by industry. SUMMARY

[0006] The present application aims to overcome the shortcomings of Au-Ti bifunctional site catalysts in the prior art, and provides a synergistic catalyst for propylene hydrooxygen epoxidation and a preparation method thereof. A carrier without Ti sites is selected, and single-atom gold catalyst and cluster or particle gold catalyst are obtained by loading gold atoms and gold clusters or gold particles respectively, and a synergistic catalyst is obtained by mixing the two in different proportions to catalyze the propylene hydrooxygen epoxidation reaction. This can not only break through the limitation that Ti sites must exist on traditional supported Au-Ti bifunctional catalysts, reducing the difficulty of catalyst development, but also effectively improve metal utilization and reduce catalyst development cost. In addition, active species with different structures can be loaded on different carriers to participate in the reaction, and the catalytic performance can be further adjusted by adjusting the number of different active structures, which is of great significance for developing high-performance and high-stability catalysts required by industry.

[0007] In a first aspect, the present application provides a synergistic catalyst for catalyzing propylene hydrooxygen epoxidation, which is obtained by physically mixing a first catalyst A and a second catalyst B, wherein A is a single-atom gold catalyst and B is a cluster or particle gold catalyst. Specifically, the gold loaded on the carrier in the first catalyst A exists in the form of single atoms; the gold loaded on the carrier in the second catalyst B exists in the form of clusters or particles, and the particle size of the gold clusters or gold particles is less than 10 nm, preferably 1-5 nm.

[0008] The present application further provides that the carriers of the first catalyst A and the second catalyst B are conventional carriers without Ti in the art, including but not limited to Ti-free molecular sieves, Ti-free metal oxides, Ti-free MOFs, and silicon dioxide, etc., preferably uncalcined full-silica molecular sieves S-1-B, uncalcined full-silica molecular sieves S-2-B formed by accumulation of nanoparticles, or silicon dioxide; and the two can select the same carrier or different carriers.

[0009] In a second aspect, the present application provides a preparation method of a synergistic catalyst for catalyzing propylene hydrooxygen epoxidation, which comprises the following steps:

[0010] (1) preparing a first catalyst A single-atom gold catalyst and a second catalyst B cluster or particle gold catalyst respectively;

[0011] (2) adding the first type of catalyst A and the second type of catalyst B into a container, and mixing the two types of catalysts by mechanical mixing to obtain a synergistic catalyst.

[0012] The present application is further provided that the first type of catalyst A and the second type of catalyst B in step (1) are prepared by conventional methods in the art, including urea deposition precipitation method, impregnation method, sol-gel method, etc., as long as the gold on the first type of catalyst A is in the form of single atom and the gold on the second type of catalyst B is in the form of cluster or particle.

[0013] The present application is further provided that the mass ratio between the first type of catalyst A and the second type of catalyst B in step (2) is not fixed, but both components must occupy a certain proportion, preferably 10:1 to 1:10.

[0014] Further, the mass of the first type of catalyst A is greater than the mass of the second type of catalyst B, preferably 3:1 to 9:1, more preferably 5:1 to 7:1.

[0015] The present application is further provided that the mechanical mixing in step (2) can be carried out by one or more than two ways of mechanical stirring, ball milling, shaking table mixing, and mechanical grinding.

[0016] The present application is further provided that the synergistic catalyst obtained in step (2) can be further subjected to high-temperature heat treatment under a certain atmosphere.

[0017] Further, the atmosphere for high-temperature heat treatment includes one or more than two mixtures of hydrogen, oxygen, propylene, nitrogen, carbon monoxide, argon, and air.

[0018] Further, the temperature for high-temperature heat treatment is 90-500℃, preferably 150-500℃, more preferably 180-450℃, the heating rate is 0.1-5℃ / min, and the heat treatment time is 1-24 hours.

[0019] The third aspect of the present application is to provide the use of the synergistic catalyst for propylene hydroperoxy epoxidation reaction.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] (1) The synergistic catalyst developed in the present application contains only Au sites, which breaks through the limitation that Ti sites must exist on traditional supported Au-Ti bifunctional catalysts, and reduces the difficulty of catalyst development.

[0022] (2) The synergistic catalyst developed by the present application has excellent propylene hydroxy epoxidation performance, the propylene oxide generation activity of which is superior to the PO generation activity of most Au-Ti bifunctional catalysts in the prior art, the selectivity of propylene oxide is as high as 76%, the stable time is more than 150h, and the synergistic catalyst has great industrial application prospect.

[0023] (3) The preparation process of the synergistic catalyst developed by the present application is simple, compared with the synergistic catalyst supported on the same carrier, the number of two active components can be arbitrarily adjusted by adjusting the addition ratio of two catalysts, and then the optimal catalytic performance of the catalyst is obtained, and the atomic utilization rate in the reaction is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The HAADF-STEM image and the EDS mapping image of the response element of the catalyst prepared for Example 5 are shown in the following figure:

[0025] Figure 2 The HAADF-STEM image and the AC-HADDF-STEM image of the catalyst prepared for Comparative Example 2 are shown in the following figure:

[0026] Figure 3 The HAADF-STEM image and the AC-HADDF-STEM image of the catalyst prepared for Comparative Example 3 are shown in the following figure:

[0027] Figure 4 The schematic diagram of the catalyst prepared for Example 2 and Example 5 loaded into the reaction tube is shown in the following figure:

[0028] Figure 5 The long stability catalytic activity evaluation results of the catalyst prepared for Example 5 are shown in the following table:

[0029] Figure 6 The catalytic activity evaluation results of the catalyst prepared for Example 4 are shown in the following table:

[0030] Figure 7 The catalytic activity evaluation results of the catalyst prepared for Comparative Example 2 are shown in the following table:

[0031] Figure 8 The catalytic performance comparison of the catalyst prepared for Example 1-Example 6 is shown in the following table: DETAILED DESCRIPTION

[0032] The technical solutions of the present application are described below in specific embodiments. It should be understood that the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application. The experimental methods in the following embodiments are not specified, and are generally carried out according to the conventional conditions or the conditions recommended by the manufacturers. Unless otherwise specified, all percentages, ratios, proportions, or parts are by weight.

[0033] Example 1

[0034] Preparation of monatomic gold catalyst Au1 / S-1-B and cluster or particulate gold catalyst Au n / S-1-B with a ratio of 1:3. The steps are as follows:

[0035] (1) Preparation of Au1 / S-1-B using urea deposition precipitation method with chloroauric acid as precursor

[0036] 1g of S-1-B, 39.6ml of water, and 0.4mL of chloroauric acid solution (0.956mg Au / mL) were sequentially added into a beaker and mixed and stirred to obtain a suspension, and 0.03g of urea was added into the above suspension; the above suspension was heated to 90℃ in a water bath and kept for 6h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au1 / S-1-B with a loading of 0.0036wt%.

[0037] (2) Preparation of Au n / S-1-B using urea deposition precipitation method with chloroauric acid as precursor

[0038] 1g of S-1-B, 39.4ml of water, and 0.6mL of chloroauric acid solution (0.956mg Au / mL) were sequentially added into a beaker and mixed and stirred to obtain a suspension, and 0.05g of urea was added into the above suspension; the above suspension was heated to 90℃ in a water bath and kept for 6h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au n / S-1-B with a loading of 0.026wt%.

[0039] (3) Mechanical stirring of the above Au1 / S-1-B and Au n / S-1-B at room temperature, with a stirring time of 15min and a mass ratio of the two catalysts of 1:3.

[0040] (4) The mixed catalyst was placed in a fixed bed reactor, and heated from room temperature to 300°C at a rate of 1.5°C / min in a reaction atmosphere composed of hydrogen:nitrogen = 1:1.47 (volume ratio), to obtain the synergistic catalyst.

[0041] Example 2

[0042] Au1 / S-1-B and Au n / S-1-B catalysts were mechanically mixed in a ratio of 1:1 to prepare the synergistic catalyst. The steps were as follows:

[0043] (1) Au1 / S-1-B was prepared by urea deposition precipitation method using chloroauric acid as a precursor

[0044] 1 g of S-1-B, 39.6 ml of water, and 0.4 mL of a chloroauric acid solution (0.956 mg of Au / mL) were sequentially added to a beaker, mixed, and stirred to obtain a suspension, and 0.03 g of urea was added to the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au1 / S-1-B with a loading of 0.0036 wt%.

[0045] (2) Au n / S-1-B was prepared by urea deposition precipitation method using chloroauric acid as a precursor

[0046] 1 g of S-1-B, 39.4 ml of water, and 0.6 mL of a chloroauric acid solution (0.956 mg of Au / mL) were sequentially added to a beaker, mixed, and stirred to obtain a suspension, and 0.05 g of urea was added to the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au n / S-1-B with a loading of 0.026 wt%.

[0047] (3) The above Au1 / S-1-B and Au n / S-1-B were mechanically stirred at room temperature, and the stirring time was 15 min, and the mass ratio of the two catalysts was 1:1.

[0048] (4) The mixed catalyst was placed in a fixed bed reactor, and heated from room temperature to 300°C at a rate of 1.5°C / min in a reaction atmosphere composed of hydrogen:nitrogen = 1:1.47 (volume ratio), to obtain the synergistic catalyst.

[0049] Example 3

[0050] Au1 / S-1-B and Au n / S-1-B catalysts were mechanically mixed in a ratio of 3:1 to prepare the synergistic catalyst. The procedure was as follows:

[0051] (1) Au1 / S-1-B was prepared by urea deposition precipitation method using chloroauric acid as precursor

[0052] 1 g of S-1-B, 39.6 ml of water, and 0.4 mL of chloroauric acid solution (0.956 mg Au / mL) were sequentially added into a beaker, mixed and stirred to obtain a suspension, and 0.03 g of urea was added into the suspension. The suspension was heated to 90°C in a water bath and kept for 6 h. The solid and liquid were separated by centrifugation and washed. The obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au1 / S-1-B with a loading of 0.0036 wt%.

[0053] (2) Au1 / S-1-B was prepared by urea deposition precipitation method using chloroauric acid as precursor n / S-1-B

[0054] 1 g of S-1-B, 39.4 ml of water, and 0.6 mL of chloroauric acid solution (0.956 mg Au / mL) were sequentially added into a beaker, mixed and stirred to obtain a suspension, and 0.05 g of urea was added into the suspension. The suspension was heated to 90°C in a water bath and kept for 6 h. The solid and liquid were separated by centrifugation and washed. The obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au1 / S-1-B with a loading of 0.026 wt%. n / S-1-B.

[0055] (3) The above Au1 / S-1-B and Au n / S-1-B were mechanically stirred at room temperature for 15 min, and the mass ratio of the two catalysts was 3:1.

[0056] (4) The mixed catalyst was placed in a fixed bed reactor, and the reaction gas atmosphere was composed of hydrogen:nitrogen = 1:1.47 (volume ratio). The temperature was increased to 300°C at a rate of 1.5°C / min from room temperature to obtain the synergistic catalyst.

[0057] Example 4

[0058] Au1 / S-1-B and Au n / S-1-B catalysts were mechanically mixed in a ratio of 5:1 to prepare the synergistic catalyst. The procedure was as follows:

[0059] (1) Au1 / S-1-B was prepared by urea deposition precipitation method using chloroauric acid as precursor

[0060] 1 g S-1-B, 39.6 ml water, 0.4 mL chloroauric acid solution (0.956 mg Au / mL) were added into a beaker in sequence, mixed and stirred to obtain a suspension, and 0.03 g urea was added into the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au1 / S-1-B with a loading of 0.0036 wt%.

[0061] (2) Au1 / S-1-B was prepared by using urea deposition precipitation method with chloroauric acid as a precursor n / S-1-B

[0062] 1 g S-1-B, 39.4 ml water, 0.6 mL chloroauric acid solution (0.956 mg Au / mL) were added into a beaker in sequence, mixed and stirred to obtain a suspension, and 0.05 g urea was added into the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au n / S-1-B with a loading of 0.026 wt%.

[0063] (3) The above Au1 / S-1-B and Au n / S-1-B were mechanically stirred at room temperature, and the stirring time was 15 min, and the mass ratio of the two catalysts was 5:1.

[0064] (4) The mixed catalyst was placed in a fixed bed reactor, and the reaction gas atmosphere was composed of hydrogen:nitrogen = 1:1.47 (volume ratio), and the temperature was increased to 300°C at a rate of 1.5°C / min from room temperature, to obtain a synergistic catalyst.

[0065] Example 5

[0066] Au1 / S-1-B and Au n / S-1-B catalysts were prepared by using chloroauric acid as a precursor, and a synergistic catalyst was prepared by mechanically mixing the two catalysts in a ratio of 7:1. The steps were as follows:

[0067] (1) Au1 / S-1-B was prepared by using urea deposition precipitation method with chloroauric acid as a precursor

[0068] 1 g S-1-B, 39.6 ml water, 0.4 mL chloroauric acid solution (0.956 mg Au / mL) were added into a beaker in sequence, mixed and stirred to obtain a suspension, and 0.03 g urea was added into the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au1 / S-1-B with a loading amount of 0.0036 wt%.

[0069] (2) Au1 / S-1-B and Au n / S-1-B were prepared by using urea deposition precipitation method with chloroauric acid as a precursor.

[0070] 1 g S-1-B, 39.4 ml water, 0.6 mL chloroauric acid solution (0.956 mg Au / mL) were added into a beaker in sequence, mixed and stirred to obtain a suspension, and 0.05 g urea was added into the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au n / S-1-B with a loading amount of 0.026 wt%.

[0071] (3) The above Au1 / S-1-B and Au n / S-1-B were mechanically stirred at room temperature, and the stirring time was 15 min, and the mass ratio of the two catalysts was 7:1.

[0072] (4) The mixed catalyst was placed in a fixed bed reactor, and the reaction gas atmosphere was composed of hydrogen:nitrogen = 1:1.47 (volume ratio), and the temperature was increased to 300°C at a rate of 1.5°C / min from room temperature, to obtain a synergistic catalyst.

[0073] Example 6

[0074] Au1 / S-1-B and Au n / S-1-B catalysts were prepared by using chloroauric acid as a precursor, and a synergistic catalyst was prepared by mechanically mixing the two catalysts in a ratio of 9:1. The steps were as follows:

[0075] (1) Au1 / S-1-B and Au

[0076] 1 g S-1-B, 39.6 ml water, 0.4 mL chloroauric acid solution (0.956 mg Au / mL) were added into a beaker in sequence, mixed and stirred to obtain a suspension, and 0.03 g urea was added into the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au1 / S-1-B with a loading amount of 0.0036 wt%.

[0077] (2) Au1 / S-1-B and Au n / S-1-B were prepared by using urea deposition precipitation method with chloroauric acid as a precursor.

[0078] 1 g S-1-B, 39.4 ml water, 0.6 mL chloroauric acid solution (0.956 mg Au / mL) were added into a beaker in sequence, mixed and stirred to obtain a suspension, and 0.05 g urea was added into the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au n / S-1-B with a loading amount of 0.026 wt%.

[0079] (3) The above Au1 / S-1-B and Au n / S-1-B were mechanically stirred at room temperature, and the stirring time was 15 min, and the mass ratio of the two catalysts was 9:1.

[0080] (4) The mixed catalyst was placed in a fixed bed reactor, and the reaction gas atmosphere was composed of hydrogen:nitrogen = 1:1.47 (volume ratio), and the temperature was increased to 300°C at a rate of 1.5°C / min from room temperature, to obtain a synergistic catalyst.

[0081] Example 7

[0082] Au1 / S-1-B and Au n / S-1-B catalysts were prepared by using chloroauric acid as a precursor, and a synergistic catalyst was prepared by mechanically mixing the two catalysts in a ratio of 7:1. The steps were as follows:

[0083] (1) Au1 / S-1-B and Au

[0084] 1 g S-1-B, 39.8 ml water, 0.2 mL chloroauric acid solution (0.956 mg Au / mL) were added into a beaker in sequence, mixed and stirred to obtain a suspension, and 0.015 g urea was added into the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au1 / S-1-B with a loading amount of 0.0018 wt%.

[0085] (2) Au1 / S-1-B was prepared by using urea deposition precipitation method with chloroauric acid as a precursor n / S-1-B

[0086] 1 g S-1-B, 39.4 ml water, 0.6 mL chloroauric acid solution (0.956 mg Au / mL) were added into a beaker in sequence, mixed and stirred to obtain a suspension, and 0.05 g urea was added into the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au n / S-1-B.

[0087] (3) The above Au1 / S-1-B and Au n / S-1-B were mechanically stirred at room temperature, and the stirring time was 15 min, and the mass ratio of the two catalysts was 7:1.

[0088] (4) The mixed catalyst was placed in a fixed bed reactor, and the reaction gas atmosphere was composed of hydrogen:nitrogen = 1:1.47 (volume ratio), and the temperature was increased to 300°C at a rate of 1.5°C / min from room temperature, to obtain a synergistic catalyst.

[0089] Example 8

[0090] Au1 / S-1-B and Au n / S-1-B catalysts were prepared by mechanical mixing at a ratio of 7:1 to prepare a synergistic catalyst. The steps are as follows:

[0091] (1) Au1 / S-1-B was prepared by using urea deposition precipitation method with chloroauric acid as a precursor

[0092] 1 g S-1-B, 39.9 ml water, 0.1 mL chloroauric acid solution (0.956 mg Au / mL) were added into a beaker in sequence, mixed and stirred to obtain a suspension, and 0.009 g urea was added into the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au1 / S-1-B with a loading amount of 0.0009 wt%.

[0093] (2) Preparation of Au1 / S-1-B using urea deposition precipitation method with chloroauric acid as a precursor n / S-1-B

[0094] 1 g S-1-B, 39.4 ml water, 0.6 mL chloroauric acid solution (0.956 mg Au / mL) were added into a beaker in sequence, mixed and stirred to obtain a suspension, and 0.05 g urea was added into the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au1 / S-1-B with a loading amount of 0.026 wt%. n / S-1-B.

[0095] (3) The above Au1 / S-1-B and Au1 / S-1-B were mechanically stirred at room temperature, and the stirring time was 15 min, and the mass ratio of the two catalysts was 7:1. n / S-1-B.

[0096] (4) The mixed catalyst was placed in a fixed bed reactor, and the reaction gas atmosphere was composed of hydrogen:nitrogen = 1:1.47 (volume ratio), and the temperature was increased to 300°C at a rate of 1.5°C / min from room temperature, to obtain a synergistic catalyst.

[0097] Example 9

[0098] Preparation of Au1 / S-1-B and Au1 / S-1-B catalysts using chloroauric acid as a precursor, and preparation of a synergistic catalyst by mechanically mixing the two catalysts in a ratio of 7:1. The steps are as follows: n / S-1-B.

[0099] (1) Preparation of Au1 / S-1-B using urea deposition precipitation method with chloroauric acid as a precursor

[0100] 1 g S-1-B, 39.6 ml water, 0.4 mL chloroauric acid solution (0.956 mg Au / mL) were added into a beaker in sequence, mixed and stirred to obtain a suspension, and 0.03 g urea was added into the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au1 / S-1-B with a loading amount of 0.0036 wt%.

[0101] (2) Au1 / S-1-B was prepared by using urea deposition precipitation method with chloroauric acid as a precursor n / S-1-B

[0102] 1 g S-1-B, 39 ml water, 1 mL chloroauric acid solution (0.956 mg Au / mL) were added into a beaker in sequence, mixed and stirred to obtain a suspension, and 0.09 g urea was added into the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au1 / S-1-B with a loading amount of 0.07 wt%. n / S-1-B.

[0103] (3) The above Au1 / S-1-B and Au1 / S-2-B were mechanically stirred at room temperature, and the stirring time was 15 min, and the mass ratio of the two catalysts was 7:1. n / S-1-B.

[0104] (4) The mixed catalyst was placed in a fixed bed reactor, and the reaction gas atmosphere was composed of hydrogen:nitrogen = 1:1.47 (volume ratio), and the temperature was increased to 300°C at a rate of 1.5°C / min from room temperature, to obtain a synergistic catalyst.

[0105] Example 10

[0106] Au1 / S-2-B and Au1 / S-1-B catalysts were prepared by using chloroauric acid as a precursor, and a synergistic catalyst was prepared by mechanically mixing the two catalysts in a ratio of 7:1. The steps were as follows: n

[0107] (1) Au1 / S-2-B was prepared by using urea deposition precipitation method with chloroauric acid as a precursor

[0108] ​A mixture of 1 g of S-2-B, 39.8 ml of water and 0.2 mL of a chloroauric acid solution (0.956 mg Au / mL) was sequentially added into a beaker, mixed and stirred to obtain a suspension, and 0.015 g of urea was added into the suspension. The suspension was heated to 90°C in a water bath and kept for 6 h. The solid and liquid were separated by centrifugation and washed. The obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au1 / S-1-B with a loading of 0.002 wt%.

[0109] (2) Au1 / S-1-B was prepared by using urea deposition precipitation method with chloroauric acid as a precursor. n / S-2-B

[0110] A mixture of 1 g of S-1-B, 39.4 ml of water and 0.6 mL of a chloroauric acid solution (0.956 mg Au / mL) was sequentially added into a beaker, mixed and stirred to obtain a suspension, and 0.05 g of urea was added into the suspension. The suspension was heated to 90°C in a water bath and kept for 6 h. The solid and liquid were separated by centrifugation and washed. The obtained solid was vacuum dried at room temperature to obtain a supported gold catalyst Au1 / S-1-B with a loading of 0.026 wt%. n / S-1-B.

[0111] (3) The above Au1 / S-2-B and Au1 / S-1-B were mechanically stirred at room temperature for 15 min, and the mass ratio of the two catalysts was 7:1. n / S-1-B.

[0112] (4) The mixed catalyst was placed in a fixed bed reactor, and the reaction gas atmosphere was composed of hydrogen:nitrogen = 1:1.47 (volume ratio). The temperature was increased from room temperature to 300°C at a rate of 1.5°C / min, and a synergistic catalyst was obtained.

[0113] Example 11

[0114] Au1 / SiO2 was prepared by using an equal-volume impregnation method with sodium thiothioaurate as a precursor, and Au1 / S-1-B was prepared by using a urea deposition precipitation method with chloroauric acid as a precursor. The synergistic catalyst was prepared by mechanically mixing Au1 / SiO2 and Au1 / S-1-B at a ratio of 1:1. The steps are as follows: n / S-1-B. n

[0115] (1) Au1 / SiO2 was prepared by using an equal-volume impregnation method with sodium thiothioaurate as a precursor.

[0116] ​1 g SiO2 was placed in a 10 mL glass beaker, then 0.2 mL of chloroauric acid solution (0.956 mg Au / mL) was measured with a pipette and dropped on the SiO2 drop by drop, then stirred uniformly with a glass rod, and left to stand at room temperature for 12 h, and filtered under vacuum to obtain a supported gold catalyst Au1 / SiO2 with a loading of 0.012 wt%.

[0117] (2) Preparation of Au / S-1-B using urea deposition precipitation method with chloroauric acid as precursor n / S-1-B

[0118] 1 g S-1-B, 39.4 ml of water, and 0.6 mL of chloroauric acid solution (0.956 mg Au / mL) were sequentially added to a beaker, mixed, and stirred to obtain a suspension, and 0.05 g of urea was added to the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was dried under vacuum at room temperature to obtain a supported gold catalyst Au n / S-1-B with a loading of 0.026 wt%.

[0119] (3) The above Au1 / SiO2 and Au n / S-1-B were mechanically stirred at room temperature for 15 min, and the mass ratio of the two catalysts was 1:1.

[0120] (4) The mixed catalyst was placed in a fixed bed reactor, and the reaction gas atmosphere was composed of hydrogen:nitrogen = 1:1.47 (volume ratio), and the temperature was increased from room temperature to 300°C at a rate of 1.5°C / min to obtain the synergistic catalyst.

[0121] Comparative Example 1

[0122] The Au / TS-1-B bifunctional catalyst was prepared using chloroauric acid as precursor, and the steps were as follows:

[0123] (1) 1 g of microporous titanium silicalite TS-1-B which was not subjected to high-temperature calcination and was blocked by a template agent, 39 mL of water, and 1 mL of chloroauric acid solution (0.956 g Au / mL) were sequentially added to a beaker, mixed, and stirred to obtain a suspension, and 0.09 g of urea was added to the suspension; the suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was dried under vacuum at room temperature.

[0124] (2) The dried solid was placed in a fixed bed reactor, and the reaction gas atmosphere was composed of hydrogen:nitrogen = 1:1.47 (volume ratio), and the temperature was increased from room temperature to 300°C at a rate of 1.5°C / min to obtain an Au-Ti bifunctional catalyst with a loading of 0.09 wt%.

[0125] Comparative Example 2

[0126] Au1 / S-1-B was prepared using chloroauric acid as precursor, the steps are as follows:

[0127] (1) 1 g of uncalcined full-silica molecular sieve S-1-B, 39.6 mL of water, 0.4 mL of chloroauric acid solution (0.956 g Au / mL) were sequentially added into a beaker and mixed and stirred to obtain a suspension, and 0.03 g of urea was added to the above suspension; the above suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature.

[0128] (2) The dried solid was placed in a fixed bed reactor, and the reaction gas atmosphere was composed of hydrogen:nitrogen = 1:1.47 (volume ratio), and the temperature was increased from room temperature to 300°C at a rate of 1.5°C / min, thereby obtaining a supported gold catalyst Au1 / S-1-B with a loading of 0.0036 wt%.

[0129] Comparative Example 3

[0130] Au / S-1-B was prepared using chloroauric acid as precursor, the steps are as follows: 1+n

[0131] (1) 1 g of uncalcined full-silica molecular sieve S-1-B, 39.5 mL of water, 0.5 mL of chloroauric acid solution (0.956 g Au / mL) were sequentially added into a beaker and mixed and stirred to obtain a suspension, and 0.045 g of urea was added to the above suspension; the above suspension was heated to 90°C in a water bath and kept for 6 h; the solid and liquid were separated by centrifugation and washed, and the obtained solid was vacuum dried at room temperature.

[0132] (2) The dried solid was placed in a fixed bed reactor, and the reaction gas atmosphere was composed of hydrogen:nitrogen = 1:1.47 (volume ratio), and the temperature was increased from room temperature to 300°C at a rate of 1.5°C / min, thereby obtaining a Au 1+n / S-1-B catalyst with a loading of 0.014 wt%.

[0133] Comparative Example 4

[0134] Au / S-1-B was prepared using chloroauric acid as precursor, the steps are as follows: n

[0135] ​​(1) 1g of uncalcined all-silica molecular sieve S-1-B, 39mL of water and 1mL of chloroauric acid solution (0.956gAu / mL) were added to a beaker and mixed and stirred to obtain a suspension. 0.09g of urea was added to the suspension. The suspension was heated to 90°C in a water bath and kept for 6h. The solid and liquid were separated by centrifugation and washed. The solid was dried under vacuum at room temperature.

[0136] (2) The dried solid was placed in a fixed-bed reactor and heated from room temperature to 300°C at a rate of 1.5°C / min in a reaction atmosphere of hydrogen:nitrogen = 1:1.47 (volume ratio), to obtain Au with a loading of 0.07wt%. n / S-1-B catalyst.

[0137] Example 12 Catalyst Characterization

[0138] The catalytic performance of the catalysts prepared in Examples 1-11 and Comparative Examples 1-4 was evaluated in the gas-phase epoxidation of propylene to propylene oxide. The propylene gas-phase epoxidation reaction was carried out in a fixed-bed reactor at atmospheric pressure. The reaction atmosphere composition was propylene:hydrogen:oxygen:nitrogen = 1:1:1:7 (volume ratio), and the space velocity was 4000-14000 mL·h. -1 ·g cat -1 The reaction temperature was 200℃, and the effluent was analyzed by gas chromatography. The catalytic results are shown in Table 1.

[0139] Table 1 Catalytic results of different catalysts in the gas-phase epoxidation of propylene

[0140]

[0141] like Figure 1 The figure shows the HAADF-STEM image and the EDS mapping image of the response element in Example 5. According to the figure, the mixing of particulate gold catalyst and single-atom gold catalyst can be seen. The all-silicon molecular sieve loaded with single-atom gold and the all-silicon molecular sieve loaded with particulate gold are separated by a nanoscale distance. The distribution of gold particles loaded on the molecular sieve can be clearly seen in the STEM image at the 50nm scale. The presence of single gold atoms loaded on the molecular sieve can be seen in the EDS mapping image.

[0142] Combination Figure 2 As shown, the HAADF-STEM and AC-HADDF-STEM images of the single-atom gold catalyst prepared in Comparative Example 2 are shown. The white part marked by the circle in the right figure is the prepared gold single atom. Figure 3The HAADF-STEM image and AC-HADDF-STEM image of the catalyst prepared for Comparative Example 3 were prepared, and the white part marked by a circle in the right image was the prepared single-atom gold, and the part marked by a box was the particle gold, and the single-atom gold and the particle gold were supported on the same carrier.

[0143] In combination Figure 5 In combination with the catalytic activity evaluation results of Comparative Example 1, the long stability catalytic activity evaluation results of Example 5 show that the synergistic catalyst of the present application has catalytic activity comparable to that of the Au-Ti bifunctional catalyst with excellent catalytic performance at present, and has high stability.

[0144] In combination Figure 6 In combination with the catalytic activity evaluation results of Comparative Example 1 and Figure 7 In combination with the catalytic activity evaluation results of Comparative Example 2, the catalytic activity of the synergistic catalyst of the present application is obviously superior to that of the single-atom gold catalyst alone.

[0145] In combination Figure 8 In combination with the catalytic activity evaluation results of Comparative Example 1 and

[0146] The present application is described in detail, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and it cannot limit the protection scope of the present application, and any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. A synergistic catalyst for the catalytic hydroperoxy-epoxidation of propene, characterized in that, The synergistic catalyst is obtained by physically mixing a first catalyst A and a second catalyst B, wherein A is a single-atom gold catalyst and B is a cluster or particle gold catalyst; The gold supported on the carrier in the first catalyst A exists in a single-atom state, and the gold supported on the carrier in the second catalyst B exists in a cluster or particle state, and the particle size of the gold cluster or gold particle is 1-5 nm; The carrier of the first catalyst A and the second catalyst B is a carrier not containing Ti, including one or more of molecular sieves, metal oxides, MOFs and silicon dioxide; the carriers of the two are the same or different.

2. The synergistic catalyst for the catalytic hydroamination epoxidation of propene according to claim 1, characterized in that, The carrier of the first catalyst A and the second catalyst B is an uncalcined full-silica molecular sieve S-1-B or silicon dioxide.

3. A process for the preparation of a synergistic catalyst for the hydro- oxyepoxidation of propylene according to any one of claims 1-2, characterized in that, The method comprises the following steps: (1) preparing a first catalyst A single-atom gold catalyst and a second catalyst B cluster or particle gold catalyst, respectively; (2) uniformly mixing the first catalyst A and the second catalyst B by mechanical mixing to obtain a synergistic catalyst.

4. The process for the preparation of a synergistic catalyst for the catalytic hydroperoxy-oxidation of propylene according to claim 3, characterized in that, The mass ratio of the first catalyst A and the second catalyst B mechanically mixed in step (2) is 10:1-1:

10.

5. The process for the preparation of a synergistic catalyst for the catalytic hydroperoxy-oxidation of propylene according to claim 4, characterized in that, The mass of the first catalyst A is greater than that of the second catalyst B, and the mass ratio of the first catalyst A and the second catalyst B is 3:1-9:

1.

6. The process for the preparation of a synergistic catalyst for the catalytic hydroperoxy-oxidation of propylene according to claim 4, characterized in that, The mass ratio of the first catalyst A and the second catalyst B is 5:1-7:

1.

7. The process for the preparation of a synergistic catalyst for the catalytic hydroperoxy-oxidation of propylene according to claim 3, characterized in that, The mechanical mixing in step (2) is carried out by one or more of mechanical stirring, ball milling, shaking table mixing and mechanical grinding.

8. The process for the preparation of a synergistic catalyst for the catalytic hydroperoxy-oxidation of propylene according to claim 3, characterized in that, The synergistic catalyst obtained in step (2) is further subjected to high-temperature heat treatment under a certain atmosphere; the atmosphere of the high-temperature heat treatment includes one or more of hydrogen, nitrogen and argon.

9. Use of the synergistic catalyst according to any one of claims 1 to 2, characterized in that, The synergistic catalyst is used for propylene hydroperoxy epoxidation.

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