Use of magnetic iron oxide red in catalyzing and oxidizing methanthiol and methods for preparing and appling same

Abstract

The present invention relates to a novel use of magnetic iron oxide red Fe.sub.21.333O.sub.32 as a catalyst in oxidizing methanthiol to prepare dimethyl disulfide. The magnetic iron oxide red Fe.sub.21.333O.sub.32 according to the present invention has extremely high catalytic selectivity in catalyzing and oxidizing methanthiol to prepare dimethyl disulfide. The magnetic iron oxide red Fe.sub.21.333O.sub.32 is prepared with a carbonate and a ferrite as raw materials, has advantages of low cost and simple preparation process, and is suitable for industrial production.

Claims

1. A method for preparing dimethyl disulfide, wherein the method comprises oxidizing methanthiol in presence of a catalyst comprising magnetic iron oxide red (Fe.sub.21.333O.sub.32).

2. The method of claim 1, wherein the catalyst consists of magnetic iron oxide red (Fe.sub.21.333O.sub.32) in an amount of 80-95 wt %, and a binder.

3. The method of claim 1, wherein the catalyst is prepared by a method comprising: preparing a solution of a soluble carbonate and a soluble ferrous salt by providing the solution in a controlled molar ratio of the carbonate to the ferrous salt of 1:0.8-1.5, stirring the solution to allow the carbonate to react with the ferrous salt in the solution to form a first mixture, and filtrating the first mixture to obtain a filter cake; calcining the filter cake at a temperature of 250-400° C. for two to five hours, then washing with water and drying the filter cake to yield the magnetic iron oxide red (Fe.sub.21.333O.sub.32); and mixing the magnetic iron oxide red (Fe.sub.21.333O.sub.32) and a binder to form a second mixture, followed by roll molding at room temperature and drying the second mixture to produce the catalyst.

4. The method of claim 3, wherein the soluble carbonate is sodium carbonate or potassium carbonate, and the soluble ferrous salt is ferrous sulfate.

5. The method of claim 4, wherein the ferrous sulfate has a concentration of 1.5-3.0 mol/L in the solution.

6. The method of claim 4, wherein the ferrous sulfate has a concentration of 2.2 mol/L in the solution.

7. The method of claim 3, wherein calcining the filter cake is at a temperature of 300° C.

8. The method of claim 3, wherein the binder is polyvinyl alcohol or red clay.

9. The method of claim 3, wherein drying the second mixture is at a temperature of no more than 100° C.

10. The method of claim 1, wherein the method comprises, introducing a gas mixture of a methanthiol gas and an oxygen containing gas into a fixed bed reactor, reacting the gas mixture in the presence of catalyst under controlled conditions of a reaction temperature of 10-150° C., a space velocity of the gas mixture of 500-2000 h.sup.−1, and a reaction pressure of atmospheric pressure, wherein a molar ratio of the oxygen in the oxygen containing gas and the methanthiol gas is equal to or greater than 1:3.

11. The method of claim 10, wherein the catalyst is prepared by a method comprising: preparing a solution of a soluble carbonate and a soluble ferrous salt by providing the solution in a controlled molar ratio of the carbonate to the ferrous salt of 1:0.8-1.5, stirring the solution to allow the carbonate to react with the ferrous salt in the solution to form a first mixture, and filtrating the first mixture to obtain a filter cake; calcining the filter cake at 250-400° C. for two to five hours, then washing with water and drying the filter cake to yield the magnetic iron oxide red (Fe.sub.21.333O.sub.32); and mixing the magnetic iron oxide red Fe.sub.21.333O.sub.32 and a binder to form a second mixture, followed by roll molding at room temperature, and drying the second mixture to produce the catalyst.

12. The method of claim 11, wherein the catalyst consists of magnetic iron oxide red Fe.sub.21.333O.sub.32 in an amount of 80-95 wt %, and a binder.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows a XRD pattern of the magnetic iron oxide red Fe.sub.21.333O.sub.32 prepared in the present invention;

(2) FIG. 2 shows a gas chromatogram of CH.sub.3SSCH.sub.3 standard sample;

(3) FIG. 3 shows a gas chromatogram of outlet gas sample.

DESCRIPTION OF EMBODIMENTS

Example 1

(4) A method for preparing a catalyst for oxidization of methanthiol in the present example comprises:

(5) (1) adding water into a beaker, placing the beaker in a water bath at 40° C., putting FeSO.sub.4.7H.sub.2O solid into the beaker, followed by stirring until the FeSO.sub.4.7H.sub.2O solid is completely dissolved in the water to obtain a FeSO.sub.4 solution having a concentration of 1.5 mol/L; then slowly adding Na.sub.2CO.sub.3 solid into the FeSO.sub.4 solution by controlling a molar ratio of the Na.sub.2CO.sub.3 to the FeSO.sub.4 to 1 to form a first mixture; stirring the first mixture for 2 h, followed by suction filtration to obtain a filter cake;

(6) (2) putting the filter cake prepared by step (1) into a muffle furnace, calcining the filter cake at 300° C. for 3 h, then washing with water and filtering for 3 times, followed by drying the filter cake at 100° C. to yield the magnetic iron oxide red Fe.sub.21.333O.sub.32; and

(7) (3) mixing 80 g of the magnetic iron oxide red Fe.sub.21.333O.sub.32 obtained in step (2) with 80 g of polyvinyl alcohol as a binder to form a second mixture, followed by roll molding at room temperature and drying the second mixture at room temperature to produce the catalyst A.

(8) The catalyst in the present example consists of magnetic iron oxide red Fe.sub.21.333O.sub.32 in an amount of 80 wt %, and the balance is the binder.

Example 2

(9) (1) Adding water into a beaker, placing the beaker in a water bath at 40° C., putting FeSO.sub.4.7H.sub.2O solid into the beaker, followed by stirring until the FeSO.sub.4.7H.sub.2O solid is completely dissolved in the water to obtain a FeSO.sub.4 solution having a concentration of 3 mol/L; then slowly adding Na.sub.2CO.sub.3 solid into the FeSO.sub.4 solution by controlling a molar ratio of the Na.sub.2CO.sub.3 to the FeSO.sub.4 to 0.8 to form a first mixture; stirring the first mixture for 2 h, followed by suction filtration to obtain a filter cake;

(10) (2) putting the filter cake prepared by step (1) into a muffle furnace, calcining the filter cake at 300° C. for 3 h, then washing with water and filtering for 3 times, followed by drying the filter cake at 120° C. to yield the magnetic iron oxide red Fe.sub.21.333O.sub.32; and

(11) (3) mixing 85 g of the magnetic iron oxide red Fe.sub.21.333O.sub.32 obtained in step (2) with 15 g of red clay as a binder to form a second mixture, followed by roll molding at room temperature and drying the second mixture at 90° C. to produce the catalyst B.

(12) The catalyst of the present example consists of magnetic iron oxide red Fe.sub.21.333O.sub.32 in an amount of 85 wt %, and the balance is the binder.

Example 3

(13) (1) Adding water into a beaker, placing the beaker in a water bath at 40° C., putting FeSO.sub.4.7H.sub.2O solid into the beaker, followed by stirring until the FeSO.sub.4.7H.sub.2O solid is completely dissolved in the water to obtain a FeSO.sub.4 solution having a concentration of 2.2 mol/L; then slowly adding Na.sub.2CO.sub.3 solid into the FeSO.sub.4 solution by controlling a molar ratio of the Na.sub.2CO.sub.3 to the FeSO.sub.4 to 1.5 to form a first mixture; stirring the first mixture for 2 h, followed by suction filtration to obtain a filter cake;

(14) (2) putting the filter cake prepared by step (1) into a muffle furnace, calcining the filter cake at 300° C. for 3 h, then washing with water and filtering for 3 times, followed by drying the filter cake at 190° C. to yield the magnetic iron oxide red Fe.sub.21.333O.sub.32; and

(15) (3) mixing 85 g of the magnetic iron oxide red Fe.sub.21.333O.sub.32 obtained in step (2) with 15 g of polyving akohol as a binder to form a second mixture, followed by roll molding at room temperature and drying the second mixture at 90° C. to produce the catalyst C.

(16) The catalyst of the present example consists of magnetic iron oxide red Fe.sub.21.333O.sub.32 in an amount of 85 wt %, and the balance is the binder.

(17) FIG. 1 shows the XRD pattern of the magnetic iron oxide red Fe.sub.21.333O.sub.32 prepared by the above examples.

Test Example

(18) In order to demonstrate the catalytic effect of the magnetic iron oxide red Fe.sub.21.333O.sub.32 for oxidization of methanthiol, the present invention provides the test example to evaluate the performance of the catalysts.

(19) The evaluation test is performed in a quartz fixed bed reactor of Ø10 mm×100 mm, filled with the catalyst to reach a height of 40 mm. A gas mixture of methanthiol gas and an oxygen with a molar ratio of 3:1-5:1 is introduced into the quartz fixed bed reactor under the condition of a reaction temperature of 10-100° C., a space velocity of 500-2000 h.sup.−1, and a reaction pressure of atmospheric pressure. The specific parameter settings are listed in the following table.

(20) The catalytic conversion rate X of the catalyst of each example is calculated according to the formula below:
X=dimethyl disulfide.sub.actual output/dimethyl disulfide.sub.theoretical output×100%
wherein dimethyl disulfide theoretical output is calculated according to the methanthiol introduced into the fixed bed reactor.

(21) In the present example, gas chromatograph is used for qualitative and quantitative detection of the dimethyl disulfide in the products. The chromatograms of the standard sample and outlet gas sample of the dimethyl disulfide are shown in FIGS. 2 and 3. According to the chromatogram, under same conditions, the peak appearance time of the CH.sub.3SSCH.sub.3 standard sample is almost the same with that of the sulfur containing compound in the outlet gas sample, so it can be determined that the sulfur containing compound in the outlet gas is CH.sub.3SSCH.sub.3.

(22) After detection, the catalytic conversion rates of the catalysts of examples 1-3 are summarized in the table below:

(23) TABLE-US-00001 gas gas gas gas reaction space reaction space reaction space reaction space temperature velocity molar temperature velocity molar temperature velocity molar temperature velocity molar ° C. h.sup.−1 ratio ° C. h.sup.−1 ratio ° C. h.sup.−1−1 ratio ° C. h.sup.−1 ratio Catalyst 10 500 3:1 25 1000 4:1 70 2000 4:1 100 700 5:1 Catalyst A 92.1% 93.3% 90.6% 94.9% Catalyst B 91.9% 92.6% 90.2% 88.7% Catalyst C 96.4% 96.8% 93.7% 95.2%

(24) From the above results it is known that the magnetic iron oxide red Fe.sub.21.333O.sub.32 has an excellent catalytic oxidation effect when used as a catalyst for oxidization of methanthiol.

(25) Obviously, the above embodiments are merely examples for clear illustration, rather than limitation for the application. For those skilled in the art, changes and modifications may be made on the basis of the above description, and it is not necessary and could not exhaust all embodiments, thus obvious changes and modifications derived from the above embodiments still fall within the protection scope of the invention.