HIERARCHICAL POROUS ZSM-5 MOLECULAR SIEVE, PREPARATION METHOD THEREFOR, HZSM-5 MOLECULAR SIEVE PREPARED THEREFROM, AND USE OF MOLECULAR SIEVE

Abstract

Provided are a hierarchical porous ZSM-5 molecular sieve and a preparation method therefor. The molecular sieve comprises micropores and mesopores, wherein the pore size of the micropores is 0.5-1.8 nm, the pore size of the mesopores is 4-30 nm, and the particle size is 0.3-4 μm. The molecular sieve is prepared by using a hemicellulose as a hard template agent. Also provided are a hierarchical porous HZSM-5 molecular sieve, which is obtained by subjecting the ZSM-5 molecular sieve to ion exchange with an ammonium chloride solution, and the use of ZSM-5 and HZSM-5 molecular sieves in the preparation of a sound-absorbing material, the sound-absorbing material made from the molecular sieve, and a speaker loaded with the sound-absorbing material. After being prepared into sound-absorbing particles, the molecular sieve can more effectively improve the absorption and desorption performances of air molecules, improve the low-frequency response of a speaker, improve the acoustic performance of the speaker, and improve the acoustic improvement stability of sound-absorbing particles in the speaker.

Claims

1-33. (canceled)

34. A hierarchical porous ZSM-5 molecular sieve, comprising micropores having a pore size of 0.5-1.8 nm and mesopores having a pore size of 4-30 nm, and the molecular sieve having a particle size of 0.3-4 μm; wherein the hierarchical porous ZSM-5 molecular sieve has a total pore volume of 0.23-0.26 ml/g, and wherein the micropores have a pore volume of 0.12-0.16 ml/g.

35. The hierarchical porous ZSM-5 molecular sieve according to claim 34, wherein the micropores have a pore size of 0.6-1.5 nm, the mesopores have a pore size of 10-28 nm, and the hierarchical porous ZSM-5 molecular sieve has a particle size of 0.7-3 μm.

36. A method for producing the hierarchical porous ZSM-5 molecular sieve according to claim 35, comprising: dissolving a silicon source, an aluminum source and an organic template agent in water, adjusting the pH to 8-12 with an inorganic base, and stirring it well to form a gel; and adding hemicellulose into the gel and mixing it well, followed by aging at an elevated temperature, and then transferring it to a reaction kettle for crystallization; thereafter, subjecting the resultant to washing, drying and calcination to remove the organic template agent and the hemicellulose, to obtain the hierarchical porous ZSM-5 molecular sieve.

37. The method according to claim 36, wherein the silicon source comprises one of silica gel, silicic acid, ethyl orthosilicate, sodium silicate, and sodium metasilicate, or any combination thereof.

38. The method according to claim 36, wherein the aluminum source comprises one of aluminum nitrate, aluminum sulfate, aluminum chloride, and aluminum isopropoxide, or any combination thereof.

39. The method according to claim 36, wherein the organic template agent comprises one of tetrapropylammonium hydroxide, tetrapropylammonium bromide, tetrapropylammonium chloride, tetramethylammonium hydroxide and tetraethylammonium hydroxide, or any combination thereof.

40. The method according to claim 36, wherein the inorganic base comprises one of sodium hydroxide, potassium hydroxide and aqueous ammonia, or any combination thereof.

41. The method according to claim 36, wherein the molar ratio of the silicon source, the aluminum source, the organic template agent, the inorganic base and the water is100:(0.15-1):(7-20):(5-10):(500-1000).

42. The method according to claim 36, wherein the mass ratio of the gel to the hemicellulose is (50-100):1.5.

43. The method according to claim 36, wherein the aging at an elevated temperature is performed at a temperature of 60° C.-98° C. for 2-4 h.

44. The method according to claim 36, wherein the crystallization is performed at a temperature of 120° C.-200° C. for 36-72 h.

45. The method according to claim 36, wherein the calcination is performed at a temperature of 500° C.-600° C. for 4-12 h.

46. A hierarchical porous HZSM-5 molecular sieve obtained by subjecting the hierarchical porous ZSM-5 molecular sieve according to claim 34 to an ion exchange in a NH.sub.4Cl solution, and drying and calcining the product.

47. The hierarchical porous HZSM-5 molecular sieve according to claim 46, wherein the NH.sub.4Cl solution has a concentration of 1-2 mol/L.

48. The hierarchical porous HZSM-5 molecular sieve according to claim 46, wherein the ion exchange is repeated 1-3 times, and for 3-6 h each time.

49. The hierarchical porous HZSM-5 molecular sieve according to claim 46, wherein 5-10 g of the hierarchical porous ZSM-5 molecular sieve is used per 100 ml of the NH.sub.4Cl solution.

50. The hierarchical porous HZSM-5 molecular sieve according to claim 46, wherein the ion exchange is performed at a temperature of 60° C.-100° C.

51. The hierarchical porous HZSM-5 molecular sieve according to claim 46, wherein the calcination after the ion exchange is performed at a temperature of 500° C.-600° C. for 3-6 h.

52. A loudspeaker comprising a back cavity loaded with a hierarchical porous molecular sieve sound-absorbing material, wherein the hierarchical porous molecular sieve sound-absorbing material comprises the hierarchical porous ZSM-5 molecular sieve according to claim 34.

53. A loudspeaker comprising a back cavity loaded with a hierarchical porous molecular sieve sound-absorbing material, wherein the hierarchical porous molecular sieve sound-absorbing material comprises the hierarchical porous HZSM-5 molecular sieve according to claim 46.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG. 1 is an XRD pattern of the hierarchical porous HZSM-5 molecular sieve synthesized in Example 1 of the present invention.

[0041] FIG. 2 is a SEM image of the hierarchical porous HZSM-5 molecular sieve synthesized in Example 1 of the present invention.

[0042] FIG. 3 is a SEM image of the sound-absorbing particles produced in Example 1 of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0043] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solutions of the present invention are now described in detail below, which, however, should not be construed as limiting the scope of implementation of the present invention.

EXAMPLE 1

[0044] This example provides a hierarchical porous ZSM-5 molecular sieve and a hierarchical porous HZSM-5 molecular sieve and a production method thereof. The production method of the hierarchical porous ZSM-5 molecular sieve and the hierarchical porous HZSM-5 molecular sieve comprises the following steps.

[0045] Under stirring, 90 g of silica gel (30% content), 8.35 g of tetrapropylammonium hydroxide, and 0.5 g of aluminum nitrate nonahydrate were added to 55 g of deionized water in sequence, stirred continuously at room temperature, and 1.2 g of NaOH was added to adjust it to pH of 9-11, to prepare a homogeneous gel.

[0046] Subsequently, 2.5 g of hemicellulose was added to the gel and stirred well, followed by warming up to 80° C. and aging for 3 h. After the aging, it was transferred into a polytetrafluoroethylene liner for a high-temperature crystallization at 180° C. for 72 h.

[0047] After the crystallization, the product was filtered, washed, dried, and calcined at 550° C. for 6 h, to obtain a sodium-based hierarchical porous ZSM-5 molecular sieve. Then, an ion exchange was carried out at 90° C. for 6 h by using 2 mol/L of NH.sub.4Cl solution, according to a proportion of 10 g of molecular sieve per 100 ml of the solution. After repeating the ion exchange for three times, the product was filtered, washed, dried, and calcined at 550° C. for 4 h, to obtain the hierarchical porous HZSM-5 molecular sieve, of which the XRD pattern is shown in FIG. 1, and the SEM image is shown in FIG. 2.

EXAMPLE 2

[0048] This example provides a hierarchical porous ZSM-5 molecular sieve and a hierarchical porous HZSM-5 molecular sieve and a production method thereof. The production method of the hierarchical porous ZSM-5 molecular sieve and the hierarchical porous HZSM-5 molecular sieve comprises the following steps.

[0049] Under stirring, 72 g of silica gel (30% content), 8.35 g of tetrapropylammonium hydroxide, and 0.5 g of aluminum nitrate nonahydrate were added to 55 g of deionized water in sequence, stirred continuously at room temperature, and 1.2 g of NaOH was added to adjust it to pH of 9-11, to prepare a homogeneous gel.

[0050] Subsequently, 2.5 g of hemicellulose was added to the gel and stirred well, followed by warming up to 80° C. and aging for 3 h. After the aging, it was transferred into a polytetrafluoroethylene liner for a high-temperature crystallization at 180° C. for 72 h.

[0051] After the crystallization, the product was filtered, washed, dried, and calcined at 550° C. for 6 h, to obtain a sodium-based hierarchical porous ZSM-5 molecular sieve. Then, an ion exchange was carried out at 90° C. for 6 h by using 2 mol/L of NH.sub.4Cl solution, according to a proportion of 10 g of molecular sieve per 100 ml of the solution. After repeating the ion exchange for three times, the product was filtered, washed, dried, and calcined at 550° C. for 4 h, to obtain the hierarchical porous HZSM-5 molecular sieve.

EXAMPLE 3

[0052] This example provides a hierarchical porous ZSM-5 molecular sieve and a hierarchical porous HZSM-5 molecular sieve and a production method thereof. The production method of the hierarchical porous ZSM-5 molecular sieve and the hierarchical porous HZSM-5 molecular sieve comprises the following steps.

[0053] Under stirring, 72 g of silica gel (30% content), 8.35 g of tetrapropylammonium hydroxide, and 0.5 g of aluminum nitrate nonahydrate were added to 55 g of deionized water in sequence, stirred continuously at room temperature, and 1.2 g of NaOH was added to adjust it to pH of 9-11, to prepare a homogeneous gel.

[0054] Subsequently, 2.5 g of hemicellulose was added to the gel and stirred well, followed by warming up to 80° C. and aging for 3 h. After the aging, it was transferred into a polytetrafluoroethylene liner for a high-temperature crystallization at 150° C. for 72 h.

[0055] After the crystallization, the product was filtered, washed, dried, and calcined at 550° C. for 6 h, to obtain a sodium-based hierarchical porous ZSM-5 molecular sieve. Then, an ion exchange was carried out at 90° C. for 6 h by using 2 mol/L of NH.sub.4Cl solution, according to a proportion of 10 g of molecular sieve per 100 ml of the solution. After repeating the ion exchange for three times, the product was filtered, washed, dried, and calcined at 550° C. for 4 h, to obtain the hierarchical porous HZSM-5 molecular sieve.

EXAMPLE 4

[0056] This example provides a hierarchical porous ZSM-5 molecular sieve and a hierarchical porous HZSM-5 molecular sieve and a production method thereof. The production method of the hierarchical porous ZSM-5 molecular sieve and the hierarchical porous HZSM-5 molecular sieve comprises the following steps.

[0057] Under stirring, 105 g of silica gel (30% content), 8.35 g of tetrapropylammonium hydroxide, and 0.5 g of aluminum nitrate nonahydrate were added to 55 g of deionized water in sequence, stirred continuously at room temperature, and 1.2 g of NaOH was added to adjust it to pH of 9-11, to prepare a homogeneous gel.

[0058] Subsequently, 2.5 g of hemicellulose was added to the gel and stirred well, followed by warming up to 80° C. and aging for 3 h. After the aging, it was transferred into a polytetrafluoroethylene liner for a high-temperature crystallization at 150° C. for 72 h.

[0059] After the crystallization, the product was filtered, washed, dried, and calcined at 550° C. for 6 h, to obtain a sodium-based hierarchical porous ZSM-5 molecular sieve. Then, an ion exchange was carried out at 90° C. for 6 h by using 2 mol/L of NH.sub.4Cl solution, according to a proportion of 10 g of molecular sieve per 100 ml of the solution. After repeating the ion exchange three times, the product was filtered, washed, dried, and calcined at 550° C. for 4 h, to obtain the hierarchical porous HZSM-5 molecular sieve.

EXAMPLE 5

[0060] This example provides a hierarchical porous ZSM-5 molecular sieve and a hierarchical porous HZSM-5 molecular sieve and a production method thereof. The production method of the hierarchical porous ZSM-5 molecular sieve and the hierarchical porous HZSM-5 molecular sieve comprises the following steps.

[0061] Under stirring, 105 g of silica gel (30% content), 8.35 g of tetrapropylammonium hydroxide, and 0.5 g of aluminum nitrate nonahydrate were added to 55 g of deionized water in sequence, stirred continuously at room temperature, and 1.2 g of NaOH was added to adjust it to pH of 9-11, to prepare a homogeneous gel.

[0062] Subsequently, 2.5 g of hemicellulose was added to the gel and stirred well, followed by warming up to 80° C. and aging for 3 h. After the aging, it was transferred into a polytetrafluoroethylene liner for a high-temperature crystallization at 180° C. for 72 h.

[0063] After the crystallization, the product was filtered, washed, dried, and calcined at 550° C. for 6 h, to obtain a sodium-based hierarchical porous ZSM-5 molecular sieve. Then, an ion exchange was carried out at 90° C. for 6 h by using 2 mol/L of NH.sub.4Cl solution, according to a proportion of 10 g of molecular sieve per 100 ml of the solution. After repeating the ion exchange three times, the product was filtered, washed, dried, and calcined at 550° C. for 4 h, to obtain the hierarchical porous HZSM-5 molecular sieve.

COMPARATIVE EXAMPLE 1

[0064] This comparative example provides a ZSM-5 molecular sieve and HZSM-5 molecular sieve and a production method thereof. The production method of the ZSM-5 molecular sieve and the HZSM-5 molecular sieve comprises the following steps.

[0065] Under stirring, 0.5 g of aluminum nitrate nonahydrate, 70 g of deionized water, 72 g of silica sol, and 9.56 g of tetrapropylammonium hydroxide were added into a beaker in sequence, and stirred continuously at room temperature for 24 h.

[0066] Subsequently, the solution was transferred into a Teflon-lined reaction kettle for a high-temperature crystallization at 160° C. for 72 h.

[0067] After the crystallization, the product was filtered, washed, dried, and calcined at 550° C. for 6 h, to obtain a sodium-based ZSM-5 molecular sieve. Then, an ion exchange was carried out at 90° C. for 6 h by using 2 mol/L of NH.sub.4Cl solution, according to a proportion of 10 g of molecular sieve per 100 ml of the solution. After repeating the ion exchange for three times, the product was filtered, washed, dried, and calcined at 550° C. for 4 h, to obtain the HZSM-5 molecular sieve.

COMPARATIVE EXAMPLE 2

[0068] This comparative example provides a ZSM-5 molecular sieve and HZSM-5 molecular sieve and a production method thereof. The production method of the ZSM-5 molecular sieve and the HZSM-5 molecular sieve comprises the following steps.

[0069] Under stirring, 0.5 g of aluminum nitrate nonahydrate, 68 g of deionized water, 90 g of silica sol, and 10.56 g of tetrapropylammonium hydroxide were added into a beaker in sequence, followed by warming up to 45° C. and aging for 24 h. After the aging, it was transferred into a polytetrafluoroethylene liner for a high-temperature crystallization at 120° C. for 72 h.

[0070] After the crystallization, the product was filtered, washed, dried, and calcined at 550° C. for 6 h, to obtain a sodium-based ZSM-5 molecular sieve. Then, an ion exchange was carried out at 90° C. for 6 h by using 2 mol/L of NH.sub.4Cl solution, according to a proportion of 10 g of molecular sieve per 100 ml of the solution. After repeating the ion exchange three times, the product was filtered, washed, dried, and calcined at 550° C. for 4 h, to obtain the HZSM-5 molecular sieve.

EXPERIMENTAL EXAMPLE

[0071] The HZSM-5 molecular sieve samples of Examples 1-5 and Comparative Examples 1-2 as described above are subjected to molding and test by specific steps as follows:

[0072] 100 g of HZSM-5 molecular sieve sample and 100 g of pure water were stirred, and then 1 g of ethylene glycol was added as a dispersing aid. After stirring for 30 min, 15 g of polystyrene acrylate emulsion (45%) was added and stirred to form a uniform suspension. It was then spray-dried to form granules, and sieved to separate products of different particle sizes. The test results of product performance are shown in the following Table 1 and Table 2.

TABLE-US-00001 TABLE 1 HZSM-5 Initial ΔF0/Hz molecular Size range of Static of sound- sieve sound-absorbing electricity absorbing No. sample particles/μm Level particles Experimental Example 1 550-600 1 115 Example 1 Experimental Example 1 480-550 1 118 Example 2 Experimental Example 1 400-480 1 121 Example 3 Experimental Example 1 250-400 1 124 Example 4 Experimental Example 1 150-250 3 126 Example 5 Experimental Example 1  50-150 5 129 Example 6

TABLE-US-00002 TABLE 2 Average particle ΔF0/Hz after size of Initial ΔF0/Hz of VOCs of HZSM-5 molecular sound-absorbing sound-absorbing No. sieve/μm particles particles Example 1 1.4 124 96 Example 2 1.1 123 87 Example 3 0.79 125 76 Example 4 1.83 121 97 Example 5 2.35 117 95 Comparative 0.28 96 43 Example 1 Comparative 4.62 107 63 Example 2

[0073] It can be seen from the results in Tables 1 and 2 that the initial ΔF0 of the sound-absorbing particles increases with the decrease in particle size thereof. However, due to the physical and chemical properties of the powder itself, the smaller the particle size, the greater the static electricity on the particle surface, so the particles having a size range of 250-480 μm will have a suitable performance With the decrease of the particle size of HZSM-5 molecular sieve, the initial ΔF0 will increase to a certain extent, but the performance against VOCs will deteriorate accordingly. When the average particle size of HZSM-5 molecular sieve is less than 0.4 μm, due to the small particle size of HZSM-5 molecular sieve, the bulk density decreases accordingly, and the bulk density of the resulting sound-absorbing particles decreases, while the initial ΔF0 of the sound-absorbing particles decreases, and the performance against VOCs deteriorates. When the particle size is larger than 2μm, the initial ΔF0 will be deteriorated accordingly. When the particle size of HZSM-5 molecular sieve is larger than 4μm, the performance against VOCs will also be degraded. In the above, ΔF0 is difference of the F0 values in the impedance meter test, and the test for VOCs is carried out by subjecting a sample to a test for VOC adsorption at 120° C. for 4h in a 250 mL closed space).

EXAMPLE 6

[0074] This example provides a hierarchical porous ZSM-5 molecular sieve and a hierarchical porous HZSM-5 molecular sieve and a production method thereof. The production method of the hierarchical porous ZSM-5 molecular sieve and the hierarchical porous HZSM-5 molecular sieve comprises the following steps.

[0075] Under stirring, 90 g of silica gel (30% content), 10.15 g of tetrapropylammonium hydroxide, and 0.5 g of aluminum nitrate nonahydrate were added to 55 g of deionized water in sequence, stirred continuously at room temperature, and 1.2 g of NaOH was added to adjust it to pH of 9-11, to prepare a homogeneous gel.

[0076] Subsequently, 2.5 g of hemicellulose was added to the gel and stirred well, followed by warming up to 80° C. and aging for 3 h. After the aging, it was transferred into a polytetrafluoroethylene liner for a high-temperature crystallization at 180° C. for 72 h.

[0077] After the crystallization, the product was filtered, washed, dried, and calcined at 550° C. for 6 h, to obtain a sodium-based hierarchical porous ZSM-5 molecular sieve. Then, an ion exchange was carried out at 90° C. for 6 h by using 2 mol/L of NH.sub.4Cl solution, according to a proportion of 10 g of molecular sieve per 100 ml of the solution. After repeating the ion exchange for three times, the product was filtered, washed, dried, and calcined at 550° C. for 4 h, to obtain the hierarchical porous HZSM-5 molecular sieve.

EXAMPLE 7

[0078] This example provides a hierarchical porous ZSM-5 molecular sieve and a hierarchical porous HZSM-5 molecular sieve and a production method thereof. The production method of the hierarchical porous ZSM-5 molecular sieve and the hierarchical porous HZSM-5 molecular sieve comprises the following steps.

[0079] Under stirring, 90 g of silica gel (30% content), 12.6 g of tetrapropylammonium hydroxide, and 0.5 g of aluminum nitrate nonahydrate were added to 55 g of deionized water in sequence, stirred continuously at room temperature, and 1.2 g of NaOH was added to adjust it to pH of 9-11, to prepare a homogeneous gel.

[0080] Subsequently, 2.5 g of hemicellulose was added to the gel and stirred well, followed by warming up to 80° C. and aging for 3 h. After the aging, it was transferred into a polytetrafluoroethylene liner for a high-temperature crystallization at 180° C. for 72 h.

[0081] After the crystallization, the product was filtered, washed, dried, and calcined at 550° C. for 6 h, to obtain a sodium-based hierarchical porous ZSM-5 molecular sieve. Then, an ion exchange was carried out at 90° C. for 6 h by using 2 mol/L of NH.sub.4Cl solution, according to a proportion of 10 g of molecular sieve per 100 ml of the solution. After repeating the ion exchange for three times, the product was filtered, washed, dried, and calcined at 550° C. for 4 h, to obtain the hierarchical porous HZSM-5 molecular sieve.

EXAMPLE 8

[0082] This example provides a hierarchical porous ZSM-5 molecular sieve and a hierarchical porous HZSM-5 molecular sieve and a production method thereof. The production method of the hierarchical porous ZSM-5 molecular sieve and the hierarchical porous HZSM-5 molecular sieve comprises the following steps.

[0083] Under stirring, 90 g of silica gel (30% content), 10.15 g of tetrapropylammonium hydroxide, and 0.5 g of aluminum nitrate nonahydrate were added to 55 g of deionized water in sequence, stirred continuously at room temperature, and 1.2 g of NaOH was added to adjust it to pH of 9-11, to prepare a homogeneous gel.

[0084] Subsequently, 2.5 g of hemicellulose was added to the gel and stirred well, followed by warming up to 85° C. and aging for 3 h. After the aging, it was transferred into a polytetrafluoroethylene liner for a high-temperature crystallization at 180° C. for 72 h.

[0085] After the crystallization, the product was filtered, washed, dried, and calcined at 550° C. for 6 h, to obtain a sodium-based hierarchical porous ZSM-5 molecular sieve. Then, an ion exchange was carried out at 90° C. for 6 h by using 2 mol/L of NH.sub.4Cl solution, according to a proportion of 10 g of molecular sieve per 100 ml of the solution. After repeating the ion exchange for three times, the product was filtered, washed, dried, and calcined at 550° C. for 4 h, to obtain the hierarchical porous HZSM-5 molecular sieve.

EXAMPLE 9

[0086] This example provides a hierarchical porous ZSM-5 molecular sieve and a hierarchical porous HZSM-5 molecular sieve and a production method thereof. The production method of the hierarchical porous ZSM-5 molecular sieve and the hierarchical porous HZSM-5 molecular sieve comprises the following steps.

[0087] Under stirring, 90 g of silica gel (30% content), 10.15 g of tetrapropylammonium hydroxide, and 0.5 g of aluminum nitrate nonahydrate were added to 55 g of deionized water in sequence, stirred continuously at room temperature, and 1.2 g of NaOH was added to adjust it to pH of 9-11, to prepare a homogeneous gel.

[0088] Subsequently, 2.5 g of hemicellulose was added to the gel and stirred well, followed by warming up to 95° C. and aging for 3 h. After the aging, it was transferred into a polytetrafluoroethylene liner for a high-temperature crystallization at 180° C. for 72 h.

[0089] After the crystallization, the product was filtered, washed, dried, and calcined at 550° C. for 6 h, to obtain a sodium-based hierarchical porous ZSM-5 molecular sieve. Then, an ion exchange was carried out at 90° C. for 6 h by using 2 mol/L of NH.sub.4Cl solution, according to a proportion of 10 g of molecular sieve per 100 ml of the solution. After repeating the ion exchange for three times, the product was filtered, washed, dried, and calcined at 550° C. for 4 h, to obtain the hierarchical porous HZSM-5 molecular sieve.

EXAMPLE 10

[0090] This example provides a hierarchical porous ZSM-5 molecular sieve and a hierarchical porous HZSM-5 molecular sieve and a production method thereof. The production method of the hierarchical porous ZSM-5 molecular sieve and the hierarchical porous HZSM-5 molecular sieve comprises the following steps.

[0091] Under stirring, 90 g of silica gel (30% content), 10.15 g of tetrapropylammonium hydroxide, and 0.5 g of aluminum nitrate nonahydrate were added to 55 g of deionized water in sequence, stirred continuously at room temperature, and 1.2 g of NaOH was added to adjust it to pH of 9-11, to prepare a homogeneous gel.

[0092] Subsequently, 2 g of hemicellulose was added to the gel and stirred well, followed by warming up to 95° C. and aging for 3 h. After the aging, it was transferred into a polytetrafluoroethylene liner for a high-temperature crystallization at 180° C. for 72 h.

[0093] After the crystallization, the product was filtered, washed, dried, and calcined at 550° C. for 6 h, to obtain a sodium-based hierarchical porous ZSM-5 molecular sieve. Then, an ion exchange was carried out at 90° C. for 6 h by using 2 mol/L of NH.sub.4Cl solution, according to a proportion of 10 g of molecular sieve per 100 ml of the solution. After repeating the ion exchange for three times, the product was filtered, washed, dried, and calcined at 550° C. for 4 h, to obtain the hierarchical porous HZSM-5 molecular sieve.

EXAMPLE 11

[0094] This example provides a hierarchical porous ZSM-5 molecular sieve and a hierarchical porous HZSM-5 molecular sieve and a production method thereof. The production method of the hierarchical porous ZSM-5 molecular sieve and the hierarchical porous HZSM-5 molecular sieve comprises the following steps.

[0095] Under stirring, 90 g of silica gel (30% content), 10.15 g of tetrapropylammonium hydroxide, and 0.5 g of aluminum nitrate nonahydrate were added to 55 g of deionized water in sequence, stirred continuously at room temperature, and 1.2 g of NaOH was added to adjust it to pH of 9-11, to prepare a homogeneous gel.

[0096] Subsequently, 3 g of hemicellulose was added to the gel and stirred well, followed by warming up to 95° C. and aging for 3 h. After the aging, it was transferred into a polytetrafluoroethylene liner for a high-temperature crystallization at 180° C. for 72 h.

[0097] After the crystallization, the product was filtered, washed, dried, and calcined at 550° C. for 6 h, to obtain a sodium-based hierarchical porous ZSM-5 molecular sieve. Then, an ion exchange was carried out at 90° C. for 6 h by using 2 mol/L of NH.sub.4Cl solution, according to a proportion of 10 g of molecular sieve per 100 ml of the solution. After repeating the ion exchange for three times, the product was filtered, washed, dried, and calcined at 550° C. for 4 h, to obtain the hierarchical porous HZSM-5 molecular sieve.

COMPARATIVE EXAMPLE 3

[0098] This example provides a hierarchical porous ZSM-5 molecular sieve and a hierarchical porous HZSM-5 molecular sieve and a production method thereof in which no hemicellulose was added. The production method of the hierarchical porous ZSM-5 molecular sieve and the hierarchical porous HZSM-5 molecular sieve comprises the following steps.

[0099] Under stirring, 90 g of silica gel (30% content), 10.15 g of tetrapropylammonium hydroxide, and 0.5 g of aluminum nitrate nonahydrate were added to 55 g of deionized water in sequence, stirred continuously at room temperature, and 1.2 g of NaOH was added to adjust it to pH of 9-11, to prepare a homogeneous gel.

[0100] Subsequently, the temperature was raised to 95° C. and allowed to aging for 3 h. After the aging, it was transferred into a polytetrafluoroethylene liner for a high-temperature crystallization at 180° C. for 72 h.

[0101] After the crystallization, the product was filtered, washed, dried, and calcined at 550° C. for 6 h, to obtain a sodium-based hierarchical porous ZSM-5 molecular sieve. Then, an ion exchange was carried out at 90° C. for 6 h by using 2 mol/L of NH.sub.4Cl solution, according to a proportion of 10 g of molecular sieve per 100 ml of the solution. After repeating the ion exchange for three times, the product was filtered, washed, dried, and calcined at 550° C. for 4 h, to obtain the hierarchical porous HZSM-5 molecular sieve.

EXPERIMENTAL EXAMPLE

[0102] The HZSM-5 molecular sieve samples of Examples 1 and 6-11 and Comparative Example 3 as described above are subjected to molding and test by the specific steps as follows:

[0103] 100 g of HZSM-5 molecular sieve sample and 100 g of pure water were stirred, and then 1 g of ethylene glycol was added as a dispersing aid. After stirring for 30 min, 15 g of polystyrene acrylate emulsion (45%) was added and stirred to form a uniform suspension. It was then spray-dried to form granules, and sieved to separate products of suitable particle sizes. Here, since the particles formed by different HZSM-5 molecular sieves have substantially the same appearance, only the SEM image of Example 1 is shown, such as FIG. 3. Subsequently, they were loaded into a device for the acoustic performance test, and the results are shown in Tables 3 and 4.

TABLE-US-00003 TABLE 3 HZSM-5 Average pore Average pore Average molecular sieve size of size of pore No. sample/μm micropores/nm mesopores/nm size/nm Example 1 1.4 0.734 17.54 5.17 Example 6 1.37 0.734 17.19 5.12 Example 7 1.32 0.734 17.43 5.09 Example 8 1.39 0.734 17.74 5.51 Example 9 1.41 0.734 17.69 5.56 Example 10 1.43 0.734 17.77 5.55 Example 11 1.39 0.734 17.89 5.79 Comparative 1.56 0.734 8.43 3.15 Example 3

TABLE-US-00004 TABLE 4 Total Pore volume Initial ΔF0/Hz ΔF0/Hz after pore of of sound- VOCs of volume/ micropores/ absorbing sound-absorbing No. (ml/g) (ml/g) particles particles Example 1 0.237 0.137 121 96 Example 6 0.245 0.145 123 93 Example 7 0.242 0.147 124 87 Example 8 0.249 0.144 119 95 Example 9 0.253 0.141 120 102 Example 10 0.249 0.145 123 100 Example 11 0.251 0.139 122 105 Comparative 0.205 0.172 120 57 Example 3

[0104] As can be seen from the experimental results in Table 3, the particle size of the HZSM-5 molecular sieve will decrease with increasing the amount of tetrapropylammonium bromide as the template agent, the amount of which in Examples 1, 6, and 7 is gradually increased. This is because more templating agent favors nucleation and reduces the grain size. The average particle size of the HZSM-5 molecular sieve is gradually increased with the increase of the aging temperature, which is gradually increased in Examples 6, 8 and 9. In addition, the average particle size of HZSM-5 molecular sieve gradually decreases with the increase of the amount of hemicellulose, the amount of which in Examples 10, 9, and 11 is gradually increased. Meanwhile, since the micropores of molecular sieves are mainly determined by the template agent, the average pore sizes of the micropores in all Examples are more or less the same. Further, because the amount of template agent used, aging temperature, and amount of hemicellulose used will change the proportions of micropores and mesopores, the average pore size will be affected accordingly.

[0105] It can be seen from the experimental results in Tables 3 and 4 that the synthesized hierarchical porous HZSM-5 molecular sieve still has better acoustic improvement performance than the comparative sample after being tested by VOCs. In particular, by increasing the amount of tetrapropylammonium bromide, which is gradually increased in Examples 1, 6 and 7, the micropores of the synthesized HZSM-5 molecular sieves are increased while the mesopores are decreased, which will make the resistance against VOCs of the sound-absorbing particles degraded to a certain extent. In addition, by increasing the amount of hemicellulose, which is 0 in Comparative Example 3, and gradually increased in Examples 10, 9 and 11, the micropores of the synthesized HZSM-5 molecular sieves are reduced while the mesopores are increased, which will improve the resistance against VOCs of the sound-absorbing particles to a certain extent. Further, by increasing the aging temperature, which is gradually increased in Examples 6, 8 and 9, the micropores of the synthesized HZSM-5 molecular sieves are reduced while the mesopores are increased, which will improve the resistance against VOCs of the sound-absorbing particles to a certain extent. In addition, since the stability of the resistance against VOCs of the sound-absorbing particles is significantly improved by the prepared hierarchical porous HZSM-5 molecular sieve, the sound-absorbing particles can maintain an excellent acoustic low-frequency response.

[0106] The above descriptions are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Simple changes or replacements made by any person skilled in the art who is familiar with the technical field on basis of the technical solutions and concepts of the present invention should be included within the protection scope of the present invention.