Method for efficiently preparing dimethyl sulfone by using synthesized iron oxide

Abstract

The invention provides a method for efficiently producing dimethyl sulfone by using a synthesized iron oxide, which can efficiently catalyze and oxidize dimethyl sulfide into dimethyl sulfone in a normal-temperature and normal-pressure flowing system by taking the synthesized iron oxide as a reaction surface. The product is easy to collect, and no other by-product is generated. The method is simple and easy to operate, raw materials are easy to obtain and low in cost, and repeated and effective utilization of the catalyst can be achieved.

Description

Technical Field

[0001] The invention relates to the field of catalytic technology, and relates to a method for preparing dimethyl sulfone by using synthetic iron oxide, and specifically relates to a method for preparing dimethyl sulfone by using synthetic iron oxide to catalytically oxidize dimethyl sulfide at normal temperature and pressure. Background Art

[0002] Dimethyl sulfone is an essential nutrient for human health and is widely used in the fields of sulfur nutrient supplementation and disease treatment for humans and livestock. In addition, dimethyl sulfone is also an important raw material and solvent for industrial production and is widely used in the fields of fine chemical production and testing.

[0003] At present, in industrial production, dimethyl sulfone is usually obtained by oxidizing dimethyl sulfoxide with hydrogen peroxide or nitric acid. The reaction conditions are very harsh, such as the need for a high temperature environment (140-145°C), accompanied by the production of by-products (such as nitrogen dioxide), and potential operational and environmental risks. In addition, the raw materials and products need to be separated later, and the process is complicated. The production of dimethyl sulfone using heterogeneous catalytic technology is a technology with application prospects. It avoids the complex process of separating raw materials and products and can achieve the repeated and effective use of catalysts. Therefore, how to achieve the efficient production of dimethyl sulfone under the actual operating conditions of heterogeneous catalysis has attracted much attention. Summary of the invention

[0004] In order to improve the above problems, the present invention provides a method for efficiently preparing dimethyl sulfone using synthetic iron oxide. The method is simple, does not use solvents, is easy to operate, and the raw materials are easily available and low in cost. Specifically, the present invention provides the following technical solutions:

[0005] A method for preparing dimethyl sulfone, the method comprising the following steps:

[0006] Using iron oxide as a reaction surface, dimethyl sulfide and ozone are introduced into a flow system at normal temperature and pressure to prepare dimethyl sulfone.

[0007] According to an embodiment of the present invention, in the above reaction, dimethyl sulfide is dimethyl sulfide standard gas. Preferably, the balance gas is nitrogen.

[0008] According to an embodiment of the present invention, the above reaction (oxidation reaction) is a heterogeneous reaction.

[0009] According to an embodiment of the present invention, the concentration of dimethyl sulfide is 100 ppbv to 600 ppbv, for example 560 ppbv.

[0010] According to an embodiment of the present invention, the ozone concentration is 100 ppbv to 800 ppbv, for example 600 ppbv.

[0011] According to an embodiment of the present invention, the reaction temperature is 10°C to 40°C, for example 25°C.

[0012] According to an embodiment of the present invention, the reaction pressure is 0.05 MPa to 0.5 MPa, for example 0.1 MPa.

[0013] According to an embodiment of the present invention, the reaction system is a gas phase flow system.

[0014] According to an embodiment of the present invention, the amount of iron oxide used is 0.005 g to 0.02 g.

[0015] According to an embodiment of the present invention, iron oxide may be supported on a carrier as a reaction surface.

[0016] According to an embodiment of the present invention, the steps for preparing the reaction surface are as follows:

[0017] The iron oxide is dispersed in solvent-1, the dispersion of the iron oxide is loaded on a carrier, and the solvent-1 is removed to obtain a reaction surface.

[0018] According to an embodiment of the present invention, the mass volume ratio of iron oxide to solvent-1 is 0.1 g-1.0 g:5 mL-20 mL, for example 0.3 g:12 mL.

[0019] According to an embodiment of the present invention, solvent-1 is a volatile solvent, such as ethanol, methanol, and the like.

[0020] According to an embodiment of the present invention, the loading amount of the dispersion of iron oxide is 0.2-0.8 mL, for example 0.4 mL.

[0021] According to an embodiment of the present invention, the iron oxide is a synthetic iron oxide.

[0022] According to an embodiment of the present invention, the preparation method may optionally further include a step of preparing iron oxide.

[0023] According to an embodiment of the present invention, the preparation steps of iron oxide are as follows:

[0024] a) preparing ferrous hydroxide;

[0025] b) Preparation of iron oxides.

[0026] According to an embodiment of the present invention, step a) specifically comprises the following steps: preparing a ferrous salt solution, adding sodium carbonate, stirring, reacting, and obtaining ferrous hydroxide.

[0027] In some embodiments, step a) specifically includes the following steps: slowly adding weighed sodium carbonate powder into the ferrous salt solution, stirring at room temperature, and reacting to obtain ferrous hydroxide.

[0028] According to an embodiment of the present invention, in the above step a), the ferrous salt is ferrous sulfate, such as ferrous sulfate heptahydrate.

[0029] According to an embodiment of the present invention, in the ferrous salt solution of step a), the concentration of ferrous iron is 2 mol / L to 2.5 mol / L, for example, 2.2 mol / L.

[0030] According to an embodiment of the present invention, the molar ratio of sodium carbonate in the above step a) to ferrous iron in the ferrous salt solution is 1-2:1, for example, 1.5:1.

[0031] According to an embodiment of the present invention, in the above step a), the stirring speed is 1200 rpm to 1500 rpm, for example, 1400 rpm.

[0032] According to an embodiment of the present invention, step b) specifically comprises the following steps: filtering, calcining, washing, filtering and drying the ferrous hydroxide prepared in step a) to obtain a synthetic iron oxide.

[0033] In some embodiments, step b) specifically includes the following steps: filtering the ferrous hydroxide prepared in step a), calcining at high temperature in a muffle furnace, washing, and drying in an oven.

[0034] According to the present invention, the calcination temperature in the above step b) is 250°C to 350°C, for example 300°C.

[0035] According to the present invention, the drying temperature in the above step b) is 190°C to 200°C.

[0036] In some embodiments, in the above step b), the temperature rising program of the high temperature calcination in the muffle furnace is: heating rate of 9°C / min, maintaining temperature of 300°C, maintaining time of 2 to 4 hours (3 hours), and then naturally cooling.

[0037] In some embodiments, in the above step b), deionized water is used for washing, and the number of times is not limited.

[0038] In some embodiments, in the above step b), the drying procedure of the oven is: heating rate is 8° C. / min, maintaining temperature at 190° C., maintaining time is 2 to 4 hours (eg, 3 hours), and then naturally cooling.

[0039] In some embodiments, the preparation method includes the following steps: dispersing the synthesized iron oxide with a volatile solvent and then loading it on a carrier, introducing dimethyl sulfide, ozone, high-purity nitrogen and high-purity oxygen, and heterogeneously catalytically oxidizing at room temperature and pressure to obtain dimethyl sulfone.

[0040] In some embodiments, the total gas flow rate is 500 mL / min.

[0041] Beneficial Effects

[0042] The present invention provides a method for efficiently preparing dimethyl sulfone from dimethyl sulfide by using iron oxide as a catalyst in a heterogeneous phase (gas-solid two-phase, no solvent used) catalyzed by dimethyl sulfide. The method can be applied to efficiently prepare dimethyl sulfone under extreme conditions, such as acidic and high temperature conditions, and does not interfere with the formation of the product dimethyl sulfoxide; at the same time, the catalyst can be recycled. In addition, the present invention does not use a solvent, the method is simple, easy to operate, and the raw materials are easily available and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is the XRD pattern of the iron oxide synthesized in Example 1;

[0044] Figure 2 The concentration variation curve of the iron oxide synthesized in Application Example 1 catalyzing the oxidation of dimethyl sulfide to generate dimethyl sulfone;

[0045] Figure 3 The concentration variation curve of the iron oxide synthesized in Application Example 2 catalyzing the oxidation of dimethyl sulfide to generate dimethyl sulfone;

[0046] Figure 4 This is the concentration variation curve of dimethyl sulfone produced by catalytic oxidation of dimethyl sulfide by the iron oxide synthesized in Application Example 3. DETAILED DESCRIPTION

[0047] The technical scheme of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0048] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0049] Example 1

[0050] Preparation of Iron Oxide:

[0051] Weigh 30.58g of ferrous sulfate heptahydrate, add 50mL of deionized water and dissolve. Weigh 17.49g of sodium carbonate powder, add it to the ferrous sulfate aqueous solution, stir it magnetically at 1400 rpm to obtain ferrous hydroxide. Filter the ferrous hydroxide, then transfer the filter cake to a crucible, and calcine the ferrous hydroxide filter cake obtained in a muffle furnace, wherein the heating rate of the muffle furnace is 9°C / min, the temperature is maintained at 300°C, the holding time is 3 hours, and then the temperature is naturally lowered to obtain crude iron oxide. The obtained crude iron oxide is washed 3 times with deionized water, then placed in an oven for drying, wherein the heating rate of the oven is 8°C / min, the temperature is maintained at 190°C, the holding time is 3 hours, and then the temperature is naturally lowered to obtain a clean synthetic iron oxide.

[0052] The X-ray diffraction pattern (XRD) of the iron oxide prepared in Example 1 is shown in Figure 1 .from Figure 1 It can be seen that the crystallinity of iron oxide is very high.

[0053] Application Example 1

[0054] Normal temperature and pressure experiment: Using the iron oxide synthesized in Example 1 as a catalyst, weigh 0.3g of iron oxide and disperse it in 12mL of anhydrous ethanol, take 0.4mL and drop it on the carrier, and naturally evaporate the ethanol in the air to serve as the reaction surface. In the normal pressure flow system, 560ppbv dimethyl sulfide and 600ppbv ozone were introduced, and the reaction temperature was controlled to be 25°C. Figure 2 As shown, the concentrations of dimethyl sulfide, dimethyl sulfoxide and dimethyl sulfone are detected in real time online by proton transfer reaction time-of-flight mass spectrometry. In the figure, a large amount of dimethyl sulfone can be seen, but dimethyl sulfoxide is not detected.

[0055] After further analysis and quantitative calculation, the results of the 2-hour reaction are as follows: the conversion rate of dimethyl sulfide is 34%; the utilization efficiency of ozone is 86%; the selectivity of dimethyl sulfone is 90%, and there is no interference with the formation of the product dimethyl sulfoxide. It was found that the synthesized iron oxide can catalyze the oxidation of dimethyl sulfide to dimethyl sulfone at room temperature and pressure.

[0056] The calculation formulas for dimethyl sulfide conversion, ozone utilization efficiency, and dimethyl sulfone selectivity are as follows:

[0057]

[0058]

[0059]

[0060] Application Example 2

[0061] The effect of acidic conditions on the production of dimethyl sulfone was studied.

[0062] Experiment at room temperature and pressure: Using the iron oxide synthesized in Example 1 as a catalyst, weigh 0.3g of the iron oxide and disperse it in 12mL of anhydrous ethanol, and take 0.4mL and drip it on the carrier. Soak the carrier loaded with the catalyst in 90mL of a pH 4.14 perchloric acid aqueous solution, take it out after 1 hour, and use it as a reaction surface after drying. 560ppbv dimethyl sulfide and 600ppbv ozone are introduced into the system, and the reaction temperature is controlled to be 25°C. Figure 3 As shown, the concentrations of dimethyl sulfide, dimethyl sulfoxide and dimethyl sulfone are detected in real time online by proton transfer reaction time-of-flight mass spectrometry. In the figure, a large amount of dimethyl sulfone can be seen, but dimethyl sulfoxide is not detected.

[0063] After further analysis and quantitative calculation, the results of the 2-hour reaction are as follows: the conversion rate of dimethyl sulfide is 42%; the utilization efficiency of ozone is 99%; the selectivity of dimethyl sulfone is 92%, and there is no interference with the formation of the product dimethyl sulfoxide. It was found that the synthesized iron oxide can still catalyze the oxidation of dimethyl sulfide to dimethyl sulfone at room temperature and pressure after acid treatment.

[0064] Application Example 3

[0065] The ability of iron oxides to produce dimethyl sulfone after high temperature treatment was studied.

[0066] Experiment at room temperature and pressure: Use the iron oxide synthesized in Example 1 as a catalyst, weigh 0.3g of iron oxide and disperse it in 12mL of anhydrous ethanol, and take 0.4mL and drip it on the carrier. The carrier loaded with the catalyst is calcined in a tubular furnace. In the heating program of the tubular furnace, the heating rate is 5℃ / min, the temperature is maintained at 500℃, the holding time is 5 hours, and then it is naturally cooled as a reaction surface. 560ppbv dimethyl sulfide and 600ppbv ozone are introduced into the system, and the reaction temperature is controlled to be 25℃. Figure 4 As shown, the concentrations of dimethyl sulfide, dimethyl sulfoxide and dimethyl sulfone are detected in real time online by proton transfer reaction time-of-flight mass spectrometry. In the figure, a large amount of dimethyl sulfone can be seen, but dimethyl sulfoxide is not detected.

[0067] After further analysis and quantitative calculation, the results of the 2-hour reaction are as follows: the conversion rate of dimethyl sulfide is 17%; the utilization efficiency of ozone is 63%; the selectivity of dimethyl sulfone is 88%, and there is no interference with the formation of the product dimethyl sulfoxide. It was found that the synthesized iron oxide can still efficiently produce dimethyl sulfone from dimethyl sulfide after high-temperature treatment.

[0068] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing dimethyl sulfone, the method comprising the following steps: Using iron oxide as a reaction surface, dimethyl sulfide and ozone are introduced into a flow system at normal temperature and pressure to prepare dimethyl sulfone.

2. The preparation method according to claim 1, characterized in that: Dimethyl sulfide is the dimethyl sulfide standard gas; preferably, the balance gas is nitrogen.

3. The preparation method according to claim 1 or 2, characterized in that: The concentration of dimethyl sulfide is 100 ppbv to 600 ppbv, for example 560 ppbv; and / or, the ozone concentration is 100 ppbv to 800 ppbv, for example 600 ppbv; and / or, the reaction temperature is 10°C to 40°C, for example 25°C; and / or, the reaction pressure is 0.05 MPa to 0.5 MPa, for example 0.1 MPa; and / or, the reaction system is a gas phase flow system; and / or, the amount of iron oxide is 0.005 g to 0.02 g; And / or, iron oxide may be loaded on a carrier to serve as a reaction surface.

4. The preparation method according to any one of claims 1 to 3, characterized in that The steps for preparing the reaction surface are as follows: Dispersing iron oxide in solvent-1, loading the iron oxide dispersion on a carrier, and removing solvent-1 to obtain a reaction surface; Preferably, the mass volume ratio of iron oxide to solvent-1 is 0.1 g-1.0 g: 5 mL-20 mL, for example 0.3 g: 12 mL; Preferably, solvent-1 is a volatile solvent, such as ethanol, methanol, etc.; Preferably, the loading amount of the dispersion of iron oxide is 0.2 to 0.8 mL, for example 0.4 mL; Preferably, the iron oxide is a synthetic iron oxide.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The preparation method may optionally further include a step of preparing iron oxide.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The preparation steps of iron oxide are as follows: a) preparing ferrous hydroxide; b) Preparation of iron oxides.

7. The preparation method according to claim 6, characterized in that: Step a) specifically comprises the following steps: preparing a ferrous salt solution, adding sodium carbonate, stirring, reacting, and obtaining ferrous hydroxide; Preferably, step a) specifically comprises the following steps: slowly adding weighed sodium carbonate powder into the ferrous salt solution, stirring at room temperature, reacting to obtain ferrous hydroxide; Preferably, in step a), the ferrous salt is ferrous sulfate, such as ferrous sulfate heptahydrate; Preferably, in the ferrous salt solution of step a), the concentration of ferrous iron is 2 mol / L to 2.5 mol / L, for example 2.2 mol / L; Preferably, the molar ratio of sodium carbonate in step a) to ferrous iron in the ferrous salt solution is 1 to 2:1, for example 1.5:1; Preferably, in step a), the stirring speed is 1200 rpm to 1500 rpm, for example 1400 rpm.

8. The preparation method according to claim 6, characterized in that: Step b) specifically comprises the following steps: filtering, calcining, washing, filtering and drying the ferrous hydroxide prepared in step a) to obtain a synthesized iron oxide; Preferably, step b) specifically comprises the following steps: filtering the ferrous hydroxide prepared in step a), calcining at high temperature in a muffle furnace, washing, and drying in an oven; Preferably, the calcination temperature in step b) is 250°C to 350°C, for example 300°C; Preferably, the drying temperature in step b) is 190°C to 200°C; Preferably, in step b), the temperature rise program of the high temperature calcination in the muffle furnace is: the heating rate is 9°C / min, the temperature is maintained at 300°C, the holding time is 2 to 4 hours (3 hours), and then the temperature is naturally lowered; Preferably, in step b), deionized water is used for washing, and the number of times is not limited; Preferably, in step b), the drying procedure of the oven is: heating rate of 8° C. / min, maintaining temperature at 190° C., maintaining time of 2 to 4 hours (eg 3 hours), and then naturally cooling.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: dispersing the synthesized iron oxide with a volatile solvent and then loading it on a carrier, introducing dimethyl sulfide, ozone, high-purity nitrogen and high-purity oxygen, and performing heterogeneous catalytic oxidation at normal temperature and pressure to obtain dimethyl sulfone.

10. The preparation method according to claim 9, characterized in that: The total gas flow rate was 500 mL / min.

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