MONOLITHIC ADSORBENT SHAPING METHOD AND APPLICATION

Abstract

A preparation method of a granular adsorbent is provided, including the following: adding a pyrrole monomer to an acidic solution, and adding an oxidant as an initiator to allow a polymerization reaction of the pyrrole monomer to produce polypyrrole (PPy), where an adsorption material powder is added to a reaction system before, during, or immediately after the polymerization reaction, and a resulting mixture is thoroughly stirred; after the polymerization reaction is completed, filtering a resulting reaction system to obtain a filter cake, which is the granular adsorbent; or subjecting the resulting reaction system to centrifugal sedimentation to obtain the monolithic adsorbent. In the present disclosure, the pyrrole monomer is subjected to a polymerization reaction to generate PPy; before being tightly stacked, network structures of PPy wrap the adsorption material powder; and the granular adsorbent is formed through sedimentation and stacking.

Claims

1. A preparation method of a granular adsorbent, comprising the steps of: adding a pyrrole monomer to an acidic solution, and adding an oxidant as an initiator to obtain a first reaction system and allow a polymerization reaction of the pyrrole monomer to produce polypyrrole (PPy); wherein an adsorption material powder is added to the first reaction system before, during, or immediately after the polymerization reaction, and uniformly stirred to obtain a second reaction system after the polymerization reaction is completed, filtering the second reaction system to obtain a filter cake, and molding the filter cake to obtain the granular adsorbent; or, subjecting the second reaction system to a centrifugal sedimentation and molding to obtain the monolithic adsorbent.

2. The preparation method of the granular adsorbent according to claim 1, wherein the adsorption material powder can be a metal-organic framework (MOF) powder, Zeolitic imidazolate framework (ZIF) powder, zeolite molecular sieve (ZMS) powder, or other powder.

3. The preparation method of the granular adsorbent according to claim 1, wherein the acidic solution is a concentrated hydrochloric acid solution with a pH<7.

4. The preparation method of the granular adsorbent according to claim 1, wherein the oxidant is a mixture of hydrogen peroxide and a ferric salt.

5. The preparation method of the granular adsorbent according to claim 4, wherein the oxidant is added at an amount such that: a molar ratio of the hydrogen peroxide to the pyrrole monomer is 4.6:1, and a molar ratio of iron ions in the ferric salt to the pyrrole monomer is 0.03:1.

6. The preparation method of the granular adsorbent according to claim 1, wherein the step of filtering is conducted using a mold with a filtering function; and after the second reaction system is added to the mold, a filtrate is filtered out, and the filter cake is formed in the mold such that the filter cake has a shape matching an inner chamber of the mold.

7. The preparation method of the granular adsorbent according to claim 2, wherein when the adsorption material powder is the MOF powder, the preparation method comprises the following steps: step 1: adding the pyrrole monomer to the acidic solution, and thoroughly stirring to obtain a first solution; step 2: adding the MOF powder to the first solution obtained in step 1, and thoroughly stirring to obtain a second solution; step 3: adding the oxidant to the second solution obtained in step 2, and stirring at room temperature to obtain the second reaction system, such that the oxidant initiates the polymerization reaction of the pyrrole monomer to produce the PPy; step 4: filtering the second reaction system obtained in step 3 to obtain the filter cake, molding the filter cake to obtain a granular MOF adsorbent; or, subjecting the second reaction system to a centrifugal sedimentation to obtain a solid residue, and molding the solid residue to obtain the monolithic MOF adsorbent.

8. The preparation method of the granular adsorbent according to claim 2, wherein when the adsorption material powder is the ZMS powder, the preparation method comprises the following steps: S1: adding the pyrrole monomer to the acidic solution, and thoroughly stirring to obtain a first solution; S2: adding the oxidant to the first solution obtained in S1, and stirring at room temperature to obtain the first reaction system, such that the oxidant initiates the polymerization reaction of the pyrrole monomer to produce the PPy; S3: washing the first reaction system obtained in S2 with water until the first reaction system is neutral, adding the ZMS powder to the first reaction system to obtain the second reaction system, and thoroughly stirring the second reaction system at room temperature; S4: filtering the second reaction system obtained in S3 to obtain the filter cake, molding the filer cake to obtain a granular ZMS adsorbent; or, subjecting the second reaction system to a centrifugal sedimentation obtain a solid residue, and molding the solid residue to obtain the monolithic ZMS adsorbent.

9. A granular adsorbent prepared by the preparation method according to claim 1.

10. The granular adsorbent according to claim 9, wherein the granular adsorbent is configured to be used as a gas adsorption material.

11. The granular adsorbent according to claim 9, wherein the adsorption material powder can be a metal-organic framework (MOF) powder, Zeolitic imidazolate framework (ZIF) powder, zeolite molecular sieve (ZMS) powder, or other powders.

12. The granular adsorbent according to claim 9, wherein the acidic solution is a concentrated hydrochloric acid solution with a pH<7.

13. The granular adsorbent according to claim 9, wherein the oxidant is a mixture of hydrogen peroxide and a ferric salt.

14. The granular adsorbent according to claim 13, wherein the oxidant is added at an amount such that: a molar ratio of the hydrogen peroxide to the pyrrole monomer is 4.6:1, and a molar ratio of iron ions in the ferric salt to the pyrrole monomer is 0.03:1.

15. The granular adsorbent according to claim 9, wherein the step of filtering is conducted using a mold with a filtering function; and after the second reaction system is added to the mold, a filtrate is filtered out, and the filter cake is formed in the mold such that the filter cake has a shape matching an inner chamber of the mold.

16. The granular adsorbent according to claim 11, wherein when the adsorption material powder is the MOF powder, the preparation method comprises the following steps: step 1: adding the pyrrole monomer to the acidic solution, and thoroughly stirring to obtain a first solution; step 2: adding the MOF powder to the first solution obtained in step 1, and thoroughly stirring to obtain a second solution; step 3: adding the oxidant to the second solution obtained in step 2, and stirring at room temperature to obtain the second reaction system, such that the oxidant initiates the polymerization reaction of the pyrrole monomer to produce the PPy; step 4: filtering the second reaction system obtained in step 3 to obtain the filter cake, molding the filter cake to obtain a granular MOF adsorbent; or, subjecting the second reaction system to a centrifugal sedimentation to obtain a solid residue, and molding the solid residue to obtain the monolithic MOF adsorbent.

17. The granular adsorbent according to claim 11, wherein when the adsorption material powder is the ZMS powder, the preparation method comprises the following steps: S1: adding the pyrrole monomer to the acidic solution, and thoroughly stirring to obtain a first solution; S2: adding the oxidant to the first solution obtained in S1, and stirring at room temperature to obtain the first reaction system, such that the oxidant initiates the polymerization reaction of the pyrrole monomer to produce the PPy; S3: washing the first reaction system obtained in S2 with water until the first reaction system is neutral, adding the ZMS powder to the first reaction system to obtain the second reaction system, and thoroughly stirring the second reaction system at room temperature; S4: filtering the second reaction system obtained in S3 to obtain the filter cake, molding the filer cake to obtain a granular ZMS adsorbent; or, subjecting the second reaction system to a centrifugal sedimentation obtain a solid residue, and molding the solid residue to obtain the monolithic ZMS adsorbent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1 is a schematic diagram of a mold with a filtering function to prepare the granular adsorbent.

[0038] FIG. 2 shows a CO.sub.2 adsorption isotherm of the granular MOF adsorbent with 20% PPy at 0° C.

[0039] FIG. 3 shows a CO.sub.2 adsorption isotherm of the granular MOF adsorbent with 15% PPy at 0° C.

[0040] FIG. 4 shows a CO.sub.2 adsorption isotherm of the granular MOF adsorbent with 10% PPy at 0° C.

[0041] FIG. 5 shows a CO.sub.2 adsorption isotherm of the granular MOF adsorbent with 5% PPy at 0° C.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] Main idea of the present disclosure: When a powder material is processed into a granular (large-particle), PPy is used to aggregate the powder material. Specifically, before, during, or immediately after the polymerization reaction of the pyrrole monomer to produce PPy, the adsorption material powder is added to a reaction system, and a resulting mixture is thoroughly stirred, such that the generated PPy agglomerates the adsorption material powder by wrapping and winding. It should be noted that, in the present disclosure, the PPy and the adsorption material powder are not simply mixed and stirred, but before the tight stacking of PPy, a loose network structure of PPy wraps and winds the adsorption material powder, and then the adsorption material powder is molded into the granular adsorbent through sedimentation and stacking.

[0043] In the prepared granular adsorbent, PPy plays the role of agglomerating an adsorption material powder (MOF, ZIF,, molecular sieve powder, etc.) by wrapping and winding, and the adsorption material powder (MOF, molecular sieve powder, etc.) is supported between a PPy molecular chain and a film layer, such that the PPy has large SSA and porosity and the PPy itself has adsorbability to some degree.

[0044] Specifically, based on the different characteristics of MOFs and zeolite molecules, the preparation method of a granular adsorbent of the present disclosure can be conducted as follows.

[0045] When a granular MOF adsorbent is prepared, the preparation method is as follows: a pyrrole monomer is added to an acidic solution, then a MOF powder is added, and a resulting mixture is thoroughly stirred; then an oxidant (hydrogen peroxide and ferric chloride) is added to a resulting solution, and a resulting mixture is thoroughly stirred until a polymerization reaction is completed to produce PPy; and a resulting reaction system is filtered, washed, and poured into a mold with a filtering function, and a filter cake is washed, and dried to obtain the monolithic MOF adsorbent.

[0046] When a granular ZMS adsorbent is prepared, the preparation method is as follows: a pyrrole monomer is added to an acidic solution, then an oxidant (hydrogen peroxide and ferric chloride) is added, and a resulting mixture is thoroughly stirred until a polymerization reaction is completed to produce PPy; a resulting reaction system is washed until neutral, and then a ZMS powder is added; and a resulting mixture is thoroughly stirred and then poured into a mold with a filtering function, and a filter cake is washed and dried to obtain the granular MOF adsorbent. Since the ZMS cannot exist in a strongly acidic environment, in the preparation of the granular ZMS adsorbent, the ZMS is added after the reaction to produce PPy is completed and the PPy is washed to remove the acid.

[0047] The method of the present disclosure involves rapid reaction, mild reaction conditions such as temperature and pressure, and no secondary pollution. A filtrate obtained after the filtration is collected to provide an acidic environment and an oxidant for the next preparation. The filtrate can be recycled many times to reduce costs. A final product of the preparation is a solid hard granule and can be directly put into an adsorption column for use.

[0048] In order to better explain the present disclosure, the present disclosure is described in detail below with reference to the accompanying drawings and specific examples.

Example 1 (20% PPy)

[0049] 1 mL of HCl was added to 55 mL of deionized water, and a resulting solution was thoroughly stirred on a magnetic stirrer; then 0.5 mL of a pyrrole monomer was added dropwise to the prepared acidic solution, and a resulting mixture was thoroughly stirred for 10 min; 2.4 g of a UiO-66 powder was added (a weight ratio of PPy to UiO-66: 1:4, namely, a UiO-66 weight proportion: 80 wt %), and a resulting mixture was thoroughly stirred for 30 min; an oxidant (2.5 mL of H.sub.2O.sub.2 and 0.08 g of FeCl.sub.3) was added, and a resulting mixture was thoroughly stirred for 6 h at room temperature until a polymerization reaction was completed; and a resulting reaction system was filtered using a device shown in FIG. 1 (PPy settled and stacked to wrap the UiO-66 powder to form a granule) to obtain a filter cake, and the filter cake was dried in a 90° C. drying oven to remove moisture to obtain a cylindrical UiO-66 granule. A mass of the PPy accounts for 20% of a mass of the cylindrical UiO-66 granule

[0050] The filter device 10 shown in FIG. 1 includes a mold 1 with a plurality of holes 11. A filter material 12 is provided at a bottom of the mold 1, and the holes 11 penetrate through the bottom of the mold 1. A joint 13 connected to a suction filtration pump is provided under the filter material 12.

[0051] In order to prevent a solid in a reaction mixture from flowing out through a bottom of the holes 11, a plastic gasket 14 can be provided. The plastic gasket is provided with a groove of a specific depth (0.5 cm), and the bottom of the mold 1 is embedded in the groove. The filter material 12 is arranged under the plastic gasket 14, and a bottom of each hole 11 is in contact with the filter material 12.

[0052] After the reaction mixture is poured into the pores 11 of the mold 1, the suction filtration pump starts to work, a filtrate is drained, and a filter cake is formed in the pores 11. The filter cake is a granular adsorbent, which has a shape matching the hole 11. According to shape and size requirements of the granular adsorbent, holes 11 of different shapes and sizes can be provided, or the formed adsorbent can be cut or broken for use.

Example 2 (15% PPy)

[0053] 1 mL of HCl was added to 55 mL of deionized water, and a resulting solution was thoroughly stirred on a magnetic stirrer; then 0.5 mL of a pyrrole monomer was added dropwise to the prepared acidic solution, and a resulting mixture was thoroughly stirred for 5 min to 15 min; 3.4 g of a UiO-66 powder was added (UiO-66 was a MOF material), and a resulting mixture was thoroughly stirred for 30 min; an oxidant (2.5 mL of H.sub.2O.sub.2 and 0.08 g of FeCl.sub.3) was added, and a resulting mixture was thoroughly stirred for 6 h at room temperature until a polymerization reaction was completed; and a resulting reaction system was filtered using a device shown in FIG. 1 (PPy settled and stacked to wrap the UiO-66 powder to form a granule) to obtain a filter cake, and the filter cake was dried in a 90° C. drying oven to remove moisture to obtain a cylindrical UiO-66 granule. A mass of the PPy accounts for 15% of a mass of the cylindrical UiO-66 granule.

Example 3 (10% PPy)

[0054] 1 mL of HCl was added to 55 mL of deionized water, and a resulting solution was thoroughly stirred on a magnetic stirrer; then 0.5 mL of a pyrrole monomer was added dropwise to the prepared acidic solution, and a resulting mixture was thoroughly stirred for 5 min to 15 min; 5.4 g of a UiO-66 powder was added (a UiO-66 weight proportion: 90 wt %), and a resulting mixture was thoroughly stirred for 30 min; an oxidant (2.5 mL of H.sub.2O.sub.2 and 0.08 g of FeCl.sub.3) was added, and a resulting mixture was thoroughly stirred for 6 h at room temperature until a polymerization reaction was completed; and a resulting reaction system was filtered using a device shown in FIG. 1 (PPy settled and stacked to wrap the UiO-66 powder to form a granule) to obtain a filter cake, and the filter cake was dried in a 90° C. drying oven to remove moisture to obtain a cylindrical UiO-66 granule. A mass of the PPy accounts for 10% of a mass of the cylindrical UiO-66 granule.

Example 4 (5% PPy)

[0055] 1 mL of HCl was added to 55 mL of deionized water, and a resulting solution was thoroughly stirred on a magnetic stirrer; then 0.5 mL of a pyrrole monomer was added dropwise to the prepared acidic solution, and a resulting mixture was thoroughly stirred for 5 min to 15 min; 11.4 g of a UiO-66 powder was added (a UiO-66 weight proportion: 95 wt %, which was a MOF material), and a resulting mixture was thoroughly stirred for 30 min; an oxidant (2.5 mL of H.sub.2O.sub.2 and 0.08 g of FeCl.sub.3) was added, and a resulting mixture was thoroughly stirred for 6 h at room temperature until a polymerization reaction was completed; and a resulting reaction system was filtered using a device shown in FIG. 1 (PPy settled and stacked to wrap the UiO-66 powder to form a granule) to obtain a filter cake, and the filter cake was dried in a 90° C. drying oven to remove moisture to obtain a cylindrical UiO-66 granule. A mass of the PPy accounts for 5% of a mass of the cylindrical UiO-66 granule.

[0056] In the cylindrical UiO-66 adsorbents prepared in Examples 1 to 4, a mass percentage of PPy is 20%, 15%, 10%, and 5%, respectively.

[0057] A physical adsorption instrument was used to conduct an adsorption test on the granular MOF adsorbents prepared in Examples 1 to 4 at 0° C. using a single-component CO.sub.2 gas, and an adsorption curve was plotted with an absolute pressure as the x-coordinate and an adsorption capacity as the y-coordinate, as shown in FIG. 2 to FIG. 5. Results show that a CO.sub.2 amount adsorbed by the sample with a UiO-66 weight proportion of 95 wt % at 0° C. is significantly higher than that adsorbed by the sample with a UiO-66 weight proportion of 100 wt % (as shown in FIG. 5), which increases the adsorption capacity and reduces the cost. As shown in FIG. 3 to FIG. 4, a CO.sub.2 amount adsorbed by the sample with a UiO-66 weight proportion of 90 wt % or 85 wt % at 0° C. is basically the same as that adsorbed by the sample with a UiO-66 weight proportion of 100 wt %, which reduces the cost. As shown in FIG. 2, a CO.sub.2 amount adsorbed by the sample with a UiO-66 weight proportion of 80 wt % at 0° C. is slightly lower than that adsorbed by the sample with a UiO-66 weight proportion of 100 wt %. Moreover, the present disclosure processes a powdery adsorbent into a bulky adsorbent, which improves the practical occasions of the adsorbent, prevents the powdery adsorbent from being taken away and lost in an airflow environment (flue or air duct) or due to water flushing, saves a lot of cost, and has very high cost performance in practical applications.

[0058] Similarly, the method of the present disclosure is also suitable for processing a ZMS powder into a granular adsorbent, as described in the following example.

Example 5

[0059] 1 mL of HCl was added to 55 mL of deionized water (with a pH of 0), and a resulting mixture was thoroughly stirred on a magnetic stirrer; 0.5 mL of a pyrrole monomer was added, and a resulting mixture was thoroughly stirred for 10 min (to produce 0.6 g of PPy); an oxidant (2.5 mL of H.sub.2O.sub.2 and 0.08 g of FeCl.sub.3) was added, and a resulting mixture was thoroughly stirred at room temperature for 6 h until a polymerization reaction was completed; the obtained PPy was washed with ultrapure water (UPW) to remove the acidic solution, and then 2.4 g of a NaY molecular sieve powder (a NaY weight proportion: 80 wt %) was added; and a resulting mixture was thoroughly stirred and then filtered using the device shown in FIG. 1 (PPy settled and stacked to wrap the molecular sieve powder to form a granule) to obtain a filter cake, and the filter cake was dried in a 90° C. drying oven to remove moisture to obtain a cylindrical NaY granular adsorbent. In the granular adsorbent, a PPy content is 20%.

[0060] Finally, it should be noted that the above examples are merely intended to describe the technical solutions of the present disclosure, rather than to limit the present disclosure. Although the present disclosure is described in detail with reference to the above examples, persons of ordinary skill in the art should understand that modifications may be made to the technical solutions described in the above examples or equivalent replacements may be made to some or all technical features thereof, which do not make the essence of corresponding technical solutions depart from the scope of the technical solutions in the examples of the present disclosure.