CN102935377A - Preparation method of catalyst for catalytic oxidation of styrene into styrene oxide - Google Patents

Abstract

The invention relates to a method for synthesizing a catalyst supported by transition metal/metal oxide by molecular sieve solid-phase grinding, in particular to a method for preparing a catalyst for catalyzing the oxidation of styrene into styrene oxide . The object of the present invention is to provide a kind of method of the catalyst of synthetic styrene oxide easily. The outstanding features of the catalyst of the present invention are: the preparation conditions of the catalyst are mild, and the method is simple and easy; the catalyst of the present invention is adopted, and the reaction product is mainly styrene oxide; the activity of the catalyst is relatively high, and the conversion rate of styrene can reach up to 98%. The selectivity of styrene oxide can reach 90%.

Description

A kind of preparation method of the catalyst that catalytic oxidation of styrene is styrene oxide

technical field

The invention relates to a method for synthesizing a catalyst supported by transition metal/metal oxide by molecular sieve solid-phase grinding, in particular to a method for preparing a catalyst for catalyzing the oxidation of styrene into styrene oxide.

Background technique

The product of styrene epoxidation reaction, styrene oxide, is an important fine chemical, which can be used as epoxy resin diluent, UV-absorber and plasticizer, and is also used in organic synthesis, pharmaceutical industry and perfume industry. An important intermediate, β-phenylethanol produced by hydrogenation of styrene oxide is the main component of clove oil, rose oil and neroli oil, and is widely used in the preparation of food, tobacco, soap and cosmetic essence. In recent years, the demand for β-phenylethyl alcohol has increased rapidly at home and abroad, and the supply of styrene oxide has been in short supply, which has brought broad development prospects for the research on the preparation of styrene oxide.

The traditional industrial production method of styrene oxide is the chlorohydrin method, which will generate a large amount of waste, cause serious environmental pollution and very high material consumption and energy consumption. The newly developed hydrogen peroxide method is widely considered as a green and environmentally friendly method for producing styrene oxide, and TS-I is considered to be a catalyst with better catalytic performance in this method. However, this production method has the problems of high cost and low utilization of H ₂ O ₂ , which seriously restrict the large-scale production application of this synthesis method. In addition, some people have developed synthesis methods of O ₂ -Zn, O ₂ -H ₂ or O ₂ -organic reducing agents. Although these methods use cheap and environmentally friendly oxygen as the oxidizing agent, there is a cost of sacrificing the co-reducing agent. disadvantages, and the realization of the technology is more difficult. In addition, there are also people who have developed a synthesis method using tert-butyl hydroperoxide as an oxygen source, such as domestic patent CN 101463020A, using Ag-y-ZrP as a catalyst, using tert-butyl hydroperoxide (TBHP) as an oxygen source, in nitrogen Under atmosphere, styrene oxide was synthesized by direct epoxidation of styrene. The conversion rate and selectivity of the reaction are relatively good, but the reaction is carried out under a nitrogen atmosphere, which is difficult to apply on a large scale, and the research on the matrix material used is still immature. Therefore, comprehensively analyzing the feasibility and economy of the above various methods, researching and developing the method of carrying out styrene epoxidation reaction with tert-butyl hydroperoxide as the oxidant is a promising process for realizing large-scale production. Because many catalysis workers are trying to find an effective catalyst to realize this synthetic process

Contents of the invention

In order to solve the problems referred to above, the object of the present invention is to provide a kind of method of the catalyst of synthetic styrene oxide easily.

The technical scheme of the present invention is: a kind of preparation method of the catalyst that catalytic oxidation of styrene is styrene oxide , its specific preparation steps are as follows:

Step 1: Use SBA-15 molecular sieve or MCM-41 molecular sieve as a carrier, transition metal salt as a precursor, and mix the carrier and precursor uniformly according to the mass ratio of 1:2-3; wherein, the transition metal salt is copper nitrate , silver nitrate or ammonium metavanadate;

Step 2: Mix the carrier and precursor uniformly in the above steps, heat at 80-160°C for 0.5h, then transfer to the ball mill while hot and grind for 1-10min; Grind in a ball mill for 1-10min, repeat the operation 2-5 times; or grind at 80-160°C,

Step 3: Transfer the ground powder to a crucible, then put the crucible into a muffle furnace, raise the temperature at a rate of 2°C/min to 400°C-600°C for 2-6h, and cool the furnace to room temperature to obtain a solid Catalysts for the Catalytic Oxidation of Styrene to Styrene Oxide by Phase Milling Supported Transition Metal/Metal Oxides.

The catalytic process of the present invention is: using Ag/SBA-15, CuO/SBA-15 or VO _x /SBA-15 as a catalyst, using tert-butyl hydroperoxide (TBHP) as an oxygen source, and acetonitrile as a solvent, in an air atmosphere In the process, under the reaction conditions of 60-80°C, styrene oxide is synthesized from styrene by direct epoxidation.

The molar ratio of styrene/tert-butyl hydroperoxide/catalyst of the present invention is 200-400/50-150/1.

The outstanding features of the catalyst of the present invention are: (1) The preparation method of the catalyst is simple and easy to operate. (2) adopt catalyst of the present invention, reaction product is mainly styrene oxide. (3) The catalytic activity of the catalyst of the present invention is as follows: the conversion rate of styrene can reach up to 98%, and the selectivity of styrene oxide can reach up to 90%.

Description of drawings

Fig. 1 is a schematic diagram of a high-resolution transmission electron microscope photo of the sample of Example 1 of the present invention.

Fig. 2 is a schematic diagram of a sample high-resolution photo of the sample in Example 2 of the present invention.

Fig. 3 is a schematic diagram of a sample high-resolution photo of the sample in Example 3 of the present invention.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the embodiments.

Example 1: After mixing 0.1g of silver nitrate and 0.2g of SBA-15 in a crucible, put them in an oven at 120°C, heat for 0.5h, grind for 1min, put them back into the oven, and grind twice, each time The grinding time is 1 min. Put the ground sample into a tube furnace, raise the temperature to 400°C at a rate of 2°C/min, keep the temperature for 4 hours, and then cool the furnace to room temperature. The obtained Ag/SBA-15 sample high-resolution transmission electron microscope photo is shown in Figure 1.

Weigh 0.05 g of catalyst powder and put it into a single-necked flask, add 5 ml of acetonitrile and 10 mmol of styrene and mix well; inject 5 mmol of tert-butyl hydroperoxide, and place the reactor in an oil bath preheated to 75°C After 4 hours of reaction, the catalyst was filtered, and the product was analyzed by GC-MS gas chromatography-mass spectrometry. The conversion rate of styrene was 72%, and the selectivity of styrene oxide was 68%.

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Example 2: After mixing 0.1g of copper nitrate and 0.3g of SBA-15 in a crucible, put them into an oven at 70°C, heat for 0.5h, grind for 6min, put them back into the oven, and grind twice, each time Grinding time is 6 minutes. Put the ground sample into a tube furnace, raise the temperature to 500°C at a rate of 2°C/min and keep it for 4 hours, then cool the furnace to room temperature. The obtained high-resolution photo of the CuO/SBA-15 sample is shown in Fig. 2.

Weigh 0.04 g of catalyst powder into a single-necked flask, add 5 ml of acetonitrile and 10 mmol of styrene and mix well; inject 5 mmol of tert-butyl hydroperoxide, and place the reactor in an oil bath preheated to 80°C After 4 hours of reaction, the catalyst was filtered, and the product was analyzed by GC-MS gas chromatography-mass spectrometry. The conversion rate of styrene was 85%, and the selectivity of styrene oxide was 75%.

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Example 3: After mixing 0.1g of ammonium metavanadate and 0.2g of SBA-15 in a crucible, put it in an oven at 100°C, heat it for 0.5h, grind it for 3min, put it back in the oven, and grind it twice, Each grinding time is 3min. The ground sample was put into a tube furnace, and the temperature was raised to 550 °C at a rate of 2 °C/min for 4 h, and then the furnace was cooled to room temperature. The obtained high-resolution photo of the VO _x /SBA-15 sample is shown in Fig. 3 .

Weigh 0.03 g of catalyst powder into a single-necked flask, add 5 ml of acetonitrile and 10 mmol of styrene and mix well; inject 5 mmol of tert-butyl hydroperoxide, and place the reactor in an oil bath preheated to 60°C After 4 hours of reaction, the catalyst was filtered, and the product was analyzed by GC-MS gas chromatography-mass spectrometry. The conversion rate of styrene was 98%, and the selectivity of styrene oxide was 90%.

Claims (1)

1. a kind of preparation method of the catalyzer that styrene catalytic oxidation is styrene oxide, it is characterized in that, its concrete preparation steps are as follows: Step 1: Use SBA-15 molecular sieve or MCM-41 molecular sieve as a carrier, transition metal salt as a precursor, and mix the carrier and precursor uniformly according to the mass ratio of 1:2-3; wherein, the transition metal salt is copper nitrate , silver nitrate or ammonium metavanadate; Step 2: Mix the carrier and precursor uniformly in the above steps, heat at 80-160°C for 0.5h, then transfer to the ball mill while hot and grind for 1-10min; Grind in a ball mill for 1-10min, repeat the operation 2-5 times; or grind at 80-160°C, Step 3: Transfer the ground powder to a crucible, then put the crucible into a muffle furnace, raise the temperature at a rate of 2°C/min to 400°C-600°C for 2-6h, and cool the furnace to room temperature to obtain a solid Catalysts for the Catalytic Oxidation of Styrene to Styrene Oxide by Phase Milling Supported Transition Metal/Metal Oxides.

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