CATALYST CAPABLE OF SIMULTANEOUSLY REMOVING COS AND H2S IN GARBAGE GASIFICATION AND PREPARATION METHOD THEREOF

Abstract

The disclosure discloses a catalyst capable of simultaneously removing COS and H.sub.2S in garbage gasification and a preparation method thereof, and belongs to the technical field of preparation of desulfurization catalysts. The method includes the following steps: pretreating an SBA-15 molecular sieve with a templating agent unremoved, which primarily includes the steps of removing the templating agent and introducing halogen atoms to modify the molecular sieve; then synthesizing an active component solution; and finally introducing active components into channels of the pretreated molecular sieve via surface tension by adopting an impregnation method, performing washing and drying, and performing calcining under an N.sub.2 atmosphere, so as to obtain the catalyst. An H.sub.2S and COS removal experiment is performed on the catalyst prepared according to the present disclosure under a simulated garbage gasification atmosphere, and a desulfurization experiment is performed as a control, so as to evaluate the desulfurization efficiency. The catalyst prepared according to the present disclosure can load the active components in fixed positions inside and outside the channels, and the components are easy to obtain, thereby having the advantages of low cost and good desulfurization effects.

Claims

1. A preparation method of a catalyst capable of simultaneously removing COS and H.sub.2S in garbage gasification, successively comprising the following steps: S1, taking a mesoporous molecular sieve SBA-15 as a carrier and pretreating the mesoporous molecular sieve SBA-15: dissolving the mesoporous molecular sieve SBA-15 in ethanol to be subjected to reflux in a water bath, performing washing and drying, dissolving the dried product in normal hexane, performing ultrasonic dispersion, dropwise adding a modifier to introduce halogen atoms to modify an outer surface of the mesoporous molecular sieve SBA-15, performing ultrasonic dispersion for a period of time, moving the ultrasonically treated mesoporous molecular sieve SBA-15 into a container for refluxing, and performing filtering, washing and drying to obtain the pretreated mesoporous molecular sieve SBA-15; S2, preparing an active component solution, wherein the active component solution is one of an MnSn solution, a FeSn solution or a ZnSn solution; S3, uniformly mixing the mesoporous molecular sieve SBA-15 pretreated in the step S1 with the active component solution, putting the mixture in a magnetic stirrer to be stirred at a uniform speed for a period of time, allowing the stirred mixture to stand, and performing drying; and S4, roasting the solid obtained by drying in the step S3 at a temperature of 450-550° C. for 4-6 hours, then naturally cooling the roasted solid to room temperature after roasting is finished, performing grinding and drying, and performing calcining under a N.sub.2 atmosphere to obtain the catalyst.

2. The preparation method of the catalyst capable of simultaneously removing COS and H.sub.2S in garbage gasification according to claim 1, wherein in the step S1, the modifier is one of chloromethyltrimethylsilane, tert-butyl bromoacetate or hydroiodic acid, and chlorine atoms are introduced by chloromethyltrimethylsilane, bromine atoms are introduced by tert-butyl bromoacetate and iodine atoms are introduced by hydroiodic acid.

3. The preparation method of the catalyst capable of simultaneously removing COS and H.sub.2S in garbage gasification according to claim 2, wherein the modifier is chloromethyltrimethylsilane.

4. The preparation method of the catalyst capable of simultaneously removing COS and H.sub.2S in garbage gasification according to claim 3, wherein the active component solution in the step S2 is the MnSn solution.

5. The preparation method of the catalyst capable of simultaneously removing COS and H.sub.2S in garbage gasification according to claim 4, wherein the MnSn solution is prepared by the following steps: weighing 2.5 g of a 50% Mn(NO.sub.3).sub.2 solution and preparing a 50 mL solution in a beaker; weighing 1.02 g of SnCl.sub.4.5H.sub.2O and preparing a 50 mL solution in a beaker; and uniformly mixing the two solutions well to obtain the MnSn solution.

6. The preparation method of the catalyst capable of simultaneously removing COS and H.sub.2S in garbage gasification according to claim 4, wherein in the step S1, the mesoporous molecular sieve SBA-15 is dissolved in ethanol, the water bath temperature is set at 60-80° C., the reflux time is 10-13 hours, and a templating agent for the mesoporous molecular sieve SBA-15 is removed by washing and drying; and the mass-volume ratio of the mesoporous molecular sieve SBA-15 to ethanol is 1:20 g/mL.

7. The preparation method of the catalyst capable of simultaneously removing COS and H.sub.2S in garbage gasification according to claim 4, wherein in the step S3, the mixture is stirred for 10-14 hours, is allowed to stand for 10-14 hours, and is dried in an oven at a temperature of 70-90° C.

8. The preparation method of the catalyst capable of simultaneously removing COS and H.sub.2S in garbage gasification according to claim 4, wherein the calcining temperature is 450-550° C.

9. The preparation method of the catalyst capable of simultaneously removing COS and H.sub.2S in garbage gasification according to claim 4, wherein in the step S1, the dried product is dissolved in normal hexane, ultrasonic treatment is performed for 20-30 min, the modifier chloromethyltrimethylsilane are added dropwise, and ultrasonic treatment is continued to be performed for 20-40 min.

10. A catalyst prepared by the preparation method of the catalyst capable of simultaneously removing COS and H.sub.2S in garbage gasification according to claim 4, wherein in the catalyst, manganese and tin account for 5-20 wt % and 5-15 wt % of the mass of the catalyst, respectively.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Further description of the present disclosure will be made below in combination with drawings:

[0033] FIG. 1 is a diagram of desulfurization efficiency of an MnSnO.sub.x/SBA-15 catalyst prepared in Embodiment 1 of the present disclosure;

[0034] FIG. 2 is XRD diffraction patterns of the SBA-15 molecular sieve and the finally prepared MnSnO.sub.x/SBA-15 catalyst in Embodiment 1 of the present disclosure.

DETAILED DESCRIPTION

[0035] First, a related detection method of the present disclosure is described below:

[0036] A method of evaluating activity of the catalyst of the present disclosure is as follows:

[0037] A detection method adopts a fixed bed reactor, a gas chromatograph and a flame photometric detector.

[0038] Steps for Detecting Activity of an Adsorbent:

[0039] putting the prepared MnSnO.sub.x/SBA-15 catalyst in a tubular furnace of the fixed bed reactor; controlling flows of COS, H.sub.2S, H.sub.2O and N.sub.2 at an air inlet by a mass flowmeter; and detecting concentrations of H.sub.2S and COS at an outlet by using 9790 II gas chromatograph (SP-9790II) and the flame photometric detector (GC-FPD).

[0040] Evaluation method: the desulfurization efficiency can be obtained by means of change of concentrations of H.sub.2S in flue gas before and after. A calculating method is as shown by a formula:

[00001]$\mathrm{desulfurization}\mathrm{efficiency}=\frac{C_{\mathrm{in}}-C_{\mathrm{out}}}{C_{\mathrm{in}}}\times 100\%$

[0041] wherein C.sub.in is the concentrations of H.sub.2S and COS at the inlet and C.sub.out is the concentrations of H.sub.2S and COS at the outlet.

[0042] Further description of the present disclosure will be made below in combination with specific embodiments:

Embodiment 1

[0043] S1, pre-treatment on an SBA-15 molecular sieve with a templating agent unremoved: first, the SBA-15 molecular sieve is dissolved in ethanol to be subjected to reflux, the refluxed SBA-15 molecular sieve is washed and dried, the above operations are repeated twice, then the dried product is dissolved in normal hexane and is dispersed ultrasonically, chloromethyltrimethylsilane is dropwise added, and ultrasonic treatment is continued to be performed for 20-40 minutes; and finally, the treated SBA-15 molecular sieve is transferred into a water bath pot to be subjected to reflux for 10-13 hours, and the refluxed SBA-15 molecular sieve is filtered, washed and dried for subsequent experimental use;

[0044] S2, pre-treatment on the active component material: 2.5 g of a 50% Mn(NO.sub.3).sub.2 solution is weighed and a 50 mL solution is prepared in a beaker; 1.02 g of SnCl.sub.4.5H.sub.2O is weighed, and a 50 mL solution is prepared in a beaker; and the two solutions are uniformly mixed well to obtain an MnSn solution;

[0045] S3, 5 g of the treated SBA-15 molecular sieve is weighed and is added into the beaker containing the MnSn solution to be mixed well uniformly;

[0046] S4, the mixed solution is put in a magnetic stirrer, is stirred at a uniform speed for 10-14 hours at room temperature, is allowed to stand overnight and is then put in an oven of 70-90° C. to be dried; and

[0047] S5, the dried solid is roasted at a temperature about 450-550° C. for 4-6 hours so that manganese and tin are turned into manganese dioxide and tin oxide, the roasted solid is naturally cooled to room temperature after roasting is finished, and the cooled material is ground to about 80-100-mesh and is transferred to a vacuum drying box to obtain an MnSnO.sub.x/SBA-15 catalyst.

[0048] An experiment is performed on the MnSnO.sub.x/SBA-15 catalyst prepared in this embodiment at a temperature of 200-400° C. and an experimental result shows that the desulfurization efficiency is approximate to 100% at 350° C., shown in the FIG. 1. The XRD diffraction patterns of the SBA-15 molecular sieve and the finally prepared MnSnO.sub.x/SBA-15 catalyst are as shown in the FIG. 2. By comparing two curves, it is found that small diffraction peaks on MnSnO.sub.x/SBA-15 are diffraction peaks of manganese oxide and tin oxide.

Embodiment 2

[0049] Different from Embodiment 1,

[0050] the mixed solution in the step S2 is a FeSn solution (the steps of preparing the FeSn solution are with reference to the prior art).

[0051] A desulfurization experiment is performed by selecting simulated garbage gasification gas, wherein the simulated garbage gasification gas contains 0.2% of COS, 2.4% of H.sub.2S and the balance H.sub.2O and N.sub.2. The desulfurization experiment is performed with the COS introduction flow of 0.2 mL/min, the H.sub.2S introduction flow of 2.4 mL/min and carrier gas H.sub.2O and N.sub.2 flow of 97.4 mL/min. An experimental result shows that the desulfurization efficiency is 94% at 350° C.

Embodiment 3

[0052] Different from Embodiment 1,

[0053] the mixed solution in the step S2 is a ZnSn solution (the steps of preparing the ZnSn solution are with reference to the prior art).

[0054] A desulfurization experiment is performed by selecting simulated garbage gasification gas, wherein the simulated garbage gasification gas contains 0.2% of COS, 2.4% of H.sub.2S and the balance H.sub.2O and N.sub.2. The desulfurization experiment is performed with the COS introduction flow of 0.2 mL/min, the H.sub.2S introduction flow of 2.4 mL/min and carrier gas H.sub.2O and N.sub.2 flow of 97.4 mL/min. An experimental result shows that the desulfurization efficiency is 89% at 350° C.

[0055] It can be known from Embodiments 1-3 that the MnSnO.sub.x/SBA-15 catalyst is optimum in efficiency at 350° C. when the desulfurization experiment is performed by selecting the simulated garbage gasification gas, wherein the simulated garbage gasification gas contains 0.2% of COS, 2.4% of H.sub.2S and the balance H.sub.2O and N.sub.2.

[0056] The desulfurization efficiency is also affected by selecting different carriers.

[0057] The present disclosure researches influence on desulfurization efficiency of the prepared MnSnO.sub.x/SBA-15 catalyst at 350° C.

Embodiment 4

[0058] Different from Embodiment 1,

[0059] the active components of the catalyst are a salt solution of manganese and tin, and the carrier is a mesoporous MCM-41 molecular sieve.

[0060] A desulfurization experiment is performed by selecting simulated garbage gasification gas, wherein the simulated garbage gasification gas contains 0.2% of COS, 2.4% of H.sub.2S and the balance H.sub.2O and N.sub.2. The desulfurization experiment is performed with the COS introduction flow of 0.2 mL/min, the H.sub.2S introduction flow of 2.4 mL/min and carrier gas H.sub.2O and N.sub.2 flow of 97.4 mL/min. An experimental result shows that the desulfurization efficiency is 95% at 350° C.

Embodiment 5

[0061] Different from Embodiment 1,

[0062] the active components of the catalyst are a salt solution of manganese and tin, and the carrier is nano porous carbon powder NCP-50.

[0063] A desulfurization experiment is performed by selecting simulated garbage gasification gas, wherein the simulated garbage gasification gas contains 0.2% of COS, 2.4% of H.sub.2S and the balance H.sub.2O and N.sub.2. The desulfurization experiment is performed with the COS introduction flow of 0.2 mL/min, the H.sub.2S introduction flow of 2.4 mL/min and carrier gas H.sub.2O and N.sub.2 flow of 97.4 mL/min. An experimental result shows that the desulfurization efficiency is 97% at 350° C.

[0064] It can be known from Embodiments 1, 4 and 5 that the catalyst of the disclosure has certain influence on desulfurization as different carriers are used, and the efficiency is also different as the channel structures of the carriers are different. The MCM-41 molecular sieve is low in price. But the channels of the molecular sieve are arranged hexagonally and orderly, and the pore diameters are 2.5-4 nm, so that the active components hardly enter the channels. Even if a part of active components enter the channels, as the molecular sieve is of a one-dimensional channel structure, toxic gas is in contact with the outer surface only if any position of the channels is blocked, such that the catalyst is poor in desulfurization efficiency. As the nano porous carbon powder NCP-50 is of a three-dimensional through nano channel structure, it is more favorable to diffuse substances and load other materials; the pore diameter is adjustable within a range of 10-50 nm, the active components can be limited in the channels and are unlikely to agglomerate, such that the efficiency of the catalyst is improved obviously. But the nano porous carbon powder NCP-50 is high in price and is not suitable for industrial production. Each pore of NCP-50 is connected to 12 peripheral holes, and the channels may have the defect of collapsing easily. Thus, the desulfurization efficiency is also affected by using different halogen atom modified molecular sieves.

Embodiment 6

[0065] Different from Embodiment 1,

[0066] pre-treatment on the SBA-15 molecular sieve with a templating agent unremoved: first, the SBA-15 molecular sieve is dissolved in ethanol to be subjected to reflux, the refluxed SBA-15 molecular sieve is washed and dried, the above operations are repeated twice, then the dried product is dissolved in ethanol and is dispersed ultrasonically, and tert-butyl bromoacetate is dropwise added to introduce halogenated bromine.

[0067] Other steps are same, and finally, the MnSnO.sub.x/SBA-15 catalyst is prepared.

[0068] A desulfurization experiment is performed by selecting simulated garbage gasification gas, wherein the simulated garbage gasification gas contains 0.2% of COS, 2.4% of H.sub.2S and the balance H.sub.2O and N.sub.2. The desulfurization experiment is performed with the COS introduction flow of 0.2 mL/min, the H.sub.2S introduction flow of 2.4 mL/min and carrier gas H.sub.2O and N.sub.2 flow of 97.4 mL/min. An experimental result shows that the desulfurization efficiency is 90% at 350° C.

Embodiment 7

[0069] Different from Embodiment 1,

[0070] pre-treatment on the SBA-15 molecular sieve with a templating agent unremoved: first, the SBA-15 molecular sieve is dissolved in ethanol to be subjected to reflux, the refluxed SBA-15 molecular sieve is washed and dried, the above operations are repeated twice, then the dried product is transferred into a water bath pot at 80° C. to be stirred, and hydroiodic acid is dropwise added to introduce halogenated iodine.

[0071] Other steps are same, and finally, the MnSnO.sub.x/SBA-15 catalyst is prepared.

[0072] A desulfurization experiment is performed by selecting simulated garbage gasification gas, wherein the simulated garbage gasification gas contains 0.2% of COS, 2.4% of H.sub.2S and the balance H.sub.2O and N.sub.2. The desulfurization experiment is performed with the COS introduction flow of 0.2 mL/min, the H.sub.2S introduction flow of 2.4 mL/min and carrier gas H.sub.2O and N.sub.2 flow of 97.4 mL/min. An experimental result shows that the desulfurization efficiency is 84% at 350° C.

[0073] It can be known from Embodiments 1, 6 and 7 that the catalyst of the disclosure has certain influence on desulfurization as different modification halogen atoms are used. Si—Cl is smaller than Si—Br and Si—I in bond energy in halogen family elements, such that the active components are more easily combined with the molecular sieve.

Comparative Example 1

[0074] Different from Embodiment 1,

[0075] the step S1 specifically includes the steps: removal of a templating agent for the molecular sieve: the SBA-15 molecular sieve is screened by a mesh sieve, is washed for several times with deionized water, and is evaporated, and finally, the SBA-15 molecular sieve is roasted at 550° C. for about 6 hours under the N.sub.2 atmosphere.

[0076] Other steps are same, and finally, the MnSnO.sub.x/SBA-15 catalyst is prepared.

[0077] A desulfurization experiment is performed on the MnSnO.sub.x/SBA-15 catalyst prepared in this comparative example, and the desulfurization experiment is performed by selecting simulated garbage gasification gas, wherein the simulated garbage gasification gas contains 0.2% of COS, 2.4% of H.sub.2S and the balance H.sub.2O and N.sub.2. The desulfurization experiment is performed with the COS introduction flow of 0.2 mL/min, the H.sub.2S introduction flow of 2.4 mL/min and carrier gas H.sub.2O and N.sub.2 flow of 97.4 mL/min. An experimental result shows that the desulfurization efficiency is 91% at 350° C.

Comparative Example 2

[0078] Different from Embodiment 1,

[0079] the step S1 specifically includes the steps: first, the SBA-15 molecular sieve is dissolved in ethanol to be subjected to reflux for 10-14 hours at 60-80° C., the refluxed SBA-15 molecular sieve is washed and dried, the above operations are repeated twice, then, the dried product is dissolved in normal hexane and is treated ultrasonically for 20-30 minutes, and a certain amount of 3-aminopropyltriethoxysilane is dropwise added, and ultrasonic treatment is performed for 30-40 minutes; and finally, the treated material is transferred into a water bath pot at 50-80° C. to be subjected to reflux condensation for 10-14 hours to introduce amino.

[0080] Other methods are same, and finally, the MnSnO.sub.x/SBA-15 catalyst is prepared.

[0081] A desulfurization experiment is performed on the MnSnO.sub.x/SBA-15 catalyst prepared in this comparative example, and the desulfurization experiment is performed by selecting simulated garbage gasification gas, wherein the simulated garbage gasification gas contains 0.2% of COS, 2.4% of H.sub.2S and the balance H.sub.2O and N.sub.2. The desulfurization experiment is performed with the COS introduction flow of 0.2 mL/min, the H.sub.2S introduction flow of 2.4 mL/min and carrier gas H.sub.2O and N.sub.2 flow of 97.4 mL/min. An experimental result shows that the desulfurization efficiency is 95% at 350° C.

[0082] It can be known from the comparative example 1 and the comparative example 2 that hydroxyl modification and amino modification are performed inside and outside the SBA-15 molecular sieve respectively. Hydroxyl is a hydrophilic group, and interaction between Si—OH and the active components is facilitated due to a hydrophilic behavior of Si—OH, such that the active components are loaded inside and outside the SBA-15, but interaction between the Si—OH and the active components is not as strong as that between the halogen atoms and the active components. Amino can fix atoms by coordinate bonds, and as nitrogen-hydrogen bonds are larger than silicon-chlorine bonds in bond energy, interaction with the active components is weak.

[0083] The part not described in the present disclosure can be realized with reference to the prior art.

[0084] It should be noted that any equivalent modes or obvious variations made by those skilled in the art shall fall within the scope of protection of the present disclosure under the teaching of the description.