CATALYST INCLUDING MOLECULAR SIEVE HAVING TOPOLOGICAL PORE STRUCTURE, PREPARATION METHOD THEREFOR AND USE THEREOF

Abstract

A catalyst contains a metal oxide, and a molecular sieve, in a crystal form, having a topological pore structure. The metal oxide is centrally distributed on the surface of the molecular sieve. Grains of the molecular sieve are exposed to at least three families of crystal planes. The family of crystal plane with the largest pore size in topology is occupied by the metal oxide by no more than 30%, preferably no more than 20%, or no more than 10%.

Claims

1. A catalyst comprising a molecular sieve having a topological pore structure, the catalyst comprising a metal oxide and the molecular sieve having a topological pore structure in a crystal form, the metal oxide being concentrated on the surface of the molecular sieve; wherein the crystal grains of the molecular sieve expose at least 3 families of crystal planes, and the 1 family with the relatively largest channel size in topology is occupied by the metal oxide by no more than 30%, preferably no more than 20%, or no more than 10%.

2. The catalyst according to claim 1, characterized in that at least 70%, preferably at least 80%, or at least 90%, of the metal oxide is distributed on the 2 families of crystal planes with the topologically relatively smallest channel size; or accounting the weight of metal oxide distributed per area on the crystal plane with the topologically largest channel size as 1, then the weight of metal oxide distributed per area on the crystal plane with the topologically smallest channel size is greater than 2, preferably greater than 3.

3. The catalyst according to claim 1, characterized in that at least 50% of the metal oxide is distributed on the surface of the molecular sieve, preferably at least 70% is distributed on the surface of the molecular sieve.

4. The catalyst according to claim 1, characterized in that at most 30% of the metal oxide is distributed in a range having a distance of more than 200 nm from the surface of the molecular sieve crystal grains; preferably at most 25% is distributed in a range having a distance of more than 100 nm from the surface of the molecular sieve crystal grains.

5. The catalyst according to claim 1, characterized in that the molecular sieve is selected from the group consisting of MFI, MEL, AEL, and TON; preferably, the molecular sieve is selected from MFI and MEL structural molecular sieves; and further preferably, the molecular sieve is selected from ZSM-5, ZSM-11, Silicalite-1 and Silicalite-2; and/or the metal component of the metal oxide is selected from the group consisting of rare earth metals, Group IVB, Group VIIB, Group VIII, Group IB, Group IIB, and Group IIIA elements; preferably, the metal component of the metal oxide is selected from Cr, Zr, Mn, Ce, La, In, Ga and Zn; more preferably, the metal oxide is Cr.sub.2O.sub.3, MnO, ZnMn.sub.20O.sub.x and CrMnO.sub.x; and/or in the catalyst, the weight ratio of the metal oxide to the molecular sieve is (0.2-5.0):1, and preferably (0.4-2.5): 1.

6. The catalyst according to claim 1, characterized in that the XRD spectrum of the catalyst is substantially free of characteristic diffraction peaks of amorphous silica and/or amorphous alumina.

7. The catalyst according to claim 1, characterized in that the catalyst particles have a particle size of from 0.1 mm to 10.0 mm, preferably from 1.0 to 5.0 mm.

8. The catalyst according to claim 1, characterized in that the molecular sieve is a ZSM-5 molecular sieve; and at least 70%, preferably 80%, of the metal oxide is distributed on the crystal plane (100) and the crystal plane (101) of the ZSM-5 molecular sieve; or, the molecular sieve is a ZSM-11 molecular sieve, and at least 50%, preferably 60%, of the metal oxide is distributed on the crystal plane (101) of the ZSM-11 molecular sieve.

9. A process for preparing the catalyst according to claim 1, comprising: mixing and shaping a metal oxide, a molecular sieve in the prepared form and a binder, carrying out a second crystallization treatment in a second template agent vapor atmosphere, and calcining to obtain the catalyst, wherein the molecular sieve in the prepared form is prepared with the aid of a first templating agent that is the same as or different from the second templating agent without calcination.

10. The process according to claim 9, characterized in that the preparation of the molecular sieve comprises the preparation of a crystallization mother liquor, and an ammonium based adjuvant is added during the preparation process of the mother liquor.

11. The process according to claim 10, characterized in that the ammonium based adjuvant is a substance capable of providing ammonium ions, and is preferably selected from ammonia, urea, ammonium carbonate and ammonium bicarbonate; wherein the molar ratio of the ammonium based adjuvant to the silicon source calculated as SiO.sub.2 in the molecular sieve is 0.2-5.0, preferably 0.5-3.0.

12. The process according to claim 9, characterized in that the second template is selected from aqueous ammonia, triethylamine, tetraethylammonium bromide, tetraethylammonium hydroxide, tetrapropylammonium bromide, tetrapropylammonium hydroxide, tetrabutylammonium bromide, and tetrabutylammonium hydroxide; and/or the second crystallization is carried out under conditions comprising: a crystallization temperature of 100-180 C.; and a crystallization duration of 12-100 hours, preferably, a crystallization temperature of 105-170 C.; and a crystallization duration of 24-96 hours; and/or, the calcination is carried out under conditions comprising: a calcining temperature of 500-700 C., and a calcining duration of 2-10 hours; preferably, a calcining temperature of 520-580 C., and a calcining duration of 5-8 hours.

13. The process according to claim 9, characterized in that the weight ratio of the metal oxide/molecular sieve/binder is (0.2-5.0): 1:(0.2-0.6), preferably (0.4-2.5): 1, (0.3-0.5).

14. A process for producing aromatic hydrocarbons and/or light hydrocarbons by conversion of synthesis gas, characterized in contacting and reacting a synthesis gas as raw material with the catalyst according to claim 1, to obtain a stream comprising aromatic hydrocarbons and/or light hydrocarbons.

Description

DESCRIPTION OF DRAWINGS

[0053] In FIG. 1, panels (1), (2) and (3) are XRD spectra of the catalysts obtained in Example 7, Comparative Example 2 and Comparative Example 1, respectively; In FIG. 2, panels (1), (2), (3), (4), (5) and (6) are XRD spectra of the molecular sieves in Examples b, f, g, h, i and j, respectively; In FIG. 3, panels (1) and (2) are SEM images of the catalysts obtained in Comparative Example 2 and Example 7, respectively; In FIG. 4, panels (1), (2) and (3) are respectively scanning photographs of the catalyst obtained in Example 7, and a nano-CT photographs of crystal planes (100) and (010) of the ZSM-5 molecular sieve; In FIG. 5, panels (1), (2) and (3) are respectively scanning photographs of the catalyst obtained in Comparative Example 2, and nano-CT photographs of crystal planes (100) and (010) of the ZSM-5 molecular sieve.

EMBODIMENTS OF THE INVENTION

[0054] Reference will now be made in detail to the embodiments of the present invention, but it should be understood that the scope of the invention is not limited by the embodiments, but is defined by the appended claims.

[0055] Instrument and conditions for the XRD test of the catalyst involved by the present invention are as follows: the phase analysis of the catalyst was carried out at room temperature using an X-ray diffractometer, model Bruker D8 Advance, using a Cu-K1 radiation source (=0.15405 nm) and a graphite monochromator at a tube pressure of 40 kV, a tube current of 50 mA and a scanning range of 5 to 90.

[0056] Instrument and conditions for the SEM test of the catalyst involved by the present invention are as follows: the morphology and structure of the catalyst were observed with a scanning electron microscope (Zeiss Merlin) at an acceleration voltage of 2.0 kV.

[0057] According to the invention, a BL07W beamlines station water window soft X-ray microscopy absorption 3D microscopy imaging (Nano-CT) from National Synchrotron Radiation Laboratory, Hefei, China, was used to characterize the distribution of metal oxides on the surface of a molecular sieve.

[0058] The present invention will be described in further detail with reference to Examples.

Example A

[0059] MnO was prepared by a precipitation process: a 50% manganese nitrate solution was used as a manganese source, and ammonium carbonate was used as a precipitator. 50.11 g of manganese nitrate solution was diluted with 50 mL of deionized water to obtain a uniform solution; 19.22 g of ammonium carbonate was dissolved in 100.0 mL of deionized water. The manganese nitrate solution was added dropwise cocurrently with the ammonium carbonate solution to 20 mL of deionized water in a 70 C. thermostatic water bath with vigorous stirring. After the precipitation was finished, the mother liquor was aged in a 70 C. thermostatic waterbath for 3 h, filtered and washed with deionized water until the filtrate was neutral, and the filter cake was dried in a 100 C. oven overnight, and calcined at 500 C. (with a temperature-rising rate of 2 C./min) for 1 h to obtain MnO.

Example B

[0060] A hydrothermal process was used to synthesize a ZSM-5 molecular sieve (marked as Z5 (50)-450 nm) with a Si/Al molar ratio of 50 and an average particle size of 450 nm, comprising the steps of:

[0061] 0.41 g of aluminum isopropoxide was added to a mixed solution of 24.67 g of tetrapropylammonium hydroxide solution (25 wt %) and 17.89 g of deionized water. The mixture was placed and stirred at room temperature for 12 h, then 21.06 g of ethyl orthosilicate was added dropwise. After stirring for 12 h, 10.63 g urea was added to the mixed system and stirring was continued for 1 h. The mother liquor was transferred to a PTFE lined autoclave and hydrothermally treated in a 180 C. oven for 48 h. The liquor was centrifugally separated and repeatedly washed with deionized water until the supernatant was neutral, and dried to obtain a solid product, namely an uncalcined ZSM-5 sample, wherein an XRD spectrum thereof was shown in FIG. 2.

Example C

[0062] Cr.sub.2O.sub.3 was prepared by a precipitation process: chromium nitrate nonahydrate was used as a chromium source, and ammonium carbonate was used as a precipitator. 56.02 g of chromic nitrate was dissolved in 75 mL of deionized water; and 21.19 g of ammonium carbonate was dissolved in 100.0 mL of deionized water. The chromic nitrate solution was added dropwise cocurrently with the ammonium carbonate solution to 20 ml mL of deionized water in a 70 C. thermostatic waterbath with vigorous stirring. After the precipitation was finished, the mother liquor was aged in a 70 C. thermostatic waterbath for 3 h, filtered and washed with deionized water until the filtrate was neutral, and the filter cake was dried in a 100 C. oven overnight, and calcined at 500 C. (with a temperature-rising rate of 2 C./min) for 1 h to obtain Cr.sub.2O.sub.3.

Example D

[0063] CrMnO.sub.x was prepared by a ball mill mixing-calcining process: chromium nitrate nonahydrate and a 50% manganous nitrate solution were respectively used as a chromium source and manganese source, and ammonium carbonate was used as a precipitator. 56.02 g of chromic nitrate was dissolved in 75 mL of deionized water; and 21.19 g of ammonium carbonate was dissolved in 100.0 mL of deionized water. The chromic nitrate solution was added dropwise cocurrently with the ammonium carbonate solution to 20 mL of deionized water in a 70 C. thermostatic waterbath with vigorous stirring. After the precipitation was finished, the mother liquor was aged in a 70 C. thermostatic waterbath for 3 h, filtered and washed with deionized water until the filtrate was neutral, and the filter cake was dried in a 100 C. oven overnight, to obtain a chromium precursor. 50.11 g of manganese nitrate solution was diluted with 50 mL of deionized water to obtain a uniform solution; 19.22 g of ammonium carbonate was dissolved in 100.0 mL of deionized water. The manganous nitrate solution was added dropwise cocurrently with the ammonium carbonate solution to 20 mL of deionized water in a 70 C. thermostatic waterbath with vigorous stirring. After the precipitation was finished, the mother liquor was aged in a 70 C. thermostatic waterbath for 3 h, filtered and washed with deionized water until neutral, and the filter cake was dried in a 100 C. oven overnight, to obtain a manganese precursor. The chromium precursor and manganese precursor were mixed by ball milling, and the mixture obtained was calcined further at 500 C. (a temperature-rising rate of 2 C./min), to obtain CrMnO.sub.x.

Example E

[0064] A hydrothermal process was used to synthesize a ZSM-11 molecular sieve (marked as Z11 (50)-450 nm) with a Si/Al molar ratio of 50 and an average particle size of 450 nm, comprising the steps of:

[0065] 0.41 g of aluminum isopropoxide was added to a mixed solution of 19.67 g of tetrabutylammonium hydroxide solution (40 wt %) and 17.89 g of deionized water. The mixture was placed and stirred at room temperature for 12 h, then 21.06 g of ethyl orthosilicate was added dropwise. After stirring for 12 h, 10.63 g urea was added to the mixed system and stirring was continued for 1 h. The mother liquor was transferred to a PTFE lined autoclave and hydrothermally treated in a 180 C. oven for 48 h. The liquor was centrifugally separated and repeatedly washed with deionized water until the supernatant was neutral, and dried to obtain a solid product, namely an uncalcined ZSM-11 sample.

Example F

[0066] A hydrothermal process was used to synthesize a ZSM-5 molecular sieve (marked as Z5 (50)-200 nm) with a Si/Al molar ratio of 50 and an average particle size of 200 nm, comprising the steps of:

[0067] 0.41 g of aluminum isopropoxide was added to a mixed solution of 24.67 g of tetrapropylammonium hydroxide solution (25 wt %) and 17.89 g of deionized water. The mixture was placed and stirred at room temperature for 12 h, then 21.06 g of ethyl orthosilicate was added dropwise. After stirring for 12 h, 3.04 g urea was added to the mixed system and stirring was continued for 1 h. The mother liquor was transferred to a PTFE lined autoclave and hydrothermally treated in a 180 C. oven for 48 h. The liquor was centrifugally separated and repeatedly washed with deionized water until the supernatant was neutral, and dried to obtain a solid product, namely an uncalcined ZSM-5 sample, wherein an XRD spectrum thereof was shown in FIG. 2.

Example G

[0068] A hydrothermal process was used to synthesize a ZSM-5 molecular sieve (marked as Z5 (50)-300 nm) with a Si/Al molar ratio of 50 and an average particle size of 300 nm, comprising the steps of:

[0069] 0.41 g of aluminum isopropoxide was added to a mixed solution of 24.67 g of tetrapropylammonium hydroxide solution (25 wt %) and 17.89 g of deionized water. The mixture was placed and stirred at room temperature for 12 h, then 21.06 g of ethyl orthosilicate was added dropwise. After stirring for 12 h, 7.59 g urea was added to the mixed system and stirring was continued for 1 h. The mother liquor was transferred to a PTFE lined autoclave and hydrothermally treated in a 180 C. oven for 48 h. The liquor was centrifugally separated and repeatedly washed with deionized water until the supernatant was neutral, and dried to obtain a solid product, namely an uncalcined ZSM-5 sample, wherein an XRD spectrum thereof was shown in FIG. 2.

Example H

[0070] A hydrothermal process was used to synthesize a ZSM-5 molecular sieve (marked as Z5 (50)-700 nm) with a Si/Al molar ratio of 50 and an average particle size of 700 nm, comprising the steps of:

[0071] 0.41 g of aluminum isopropoxide was added to a mixed solution of 24.67 g of tetrapropylammonium hydroxide solution (25 wt %) and 17.89 g of deionized water. The mixture was placed and stirred at room temperature for 12 h, then 21.06 g of ethyl orthosilicate was added dropwise. After stirring for 12 h, 15.18 g urea was added to the mixed system and stirring was continued for 1 h. The mother liquor was transferred to a PTFE lined autoclave and hydrothermally treated in a 180 C. oven for 48 h. The liquor was centrifugally separated and repeatedly washed with deionized water until the supernatant was neutral, and dried to obtain a solid product, namely an uncalcined ZSM-5 sample, wherein an XRD spectrum thereof was shown in FIG. 2.

Example i

[0072] A hydrothermal process was used to synthesize a ZSM-5 molecular sieve (marked as Z5 (50)-700 nm) with a Si/Al molar ratio of 50 and an average particle size of 700 nm, comprising the steps of:

[0073] 0.41 g of aluminum isopropoxide was added to a mixed solution of 24.67 g of tetrapropylammonium hydroxide solution (25 wt %) and 17.89 g of deionized water. The mixture was placed and stirred at room temperature for 12 h, then 21.06 g of ethyl orthosilicate was added dropwise. After stirring for 12 h, 24.30 g ammonium carbonate was added to the mixed system and stirring was continued for 1 h. The mother liquor was transferred to a PTFE lined autoclave and hydrothermally treated in a 180 C. oven for 48 h. The liquor was centrifugally separated and repeatedly washed with deionized water until the supernatant was neutral, and dried to obtain a solid product, namely an uncalcined ZSM-5 sample, wherein an XRD spectrum thereof was shown in FIG. 2.

Example J

[0074] A hydrothermal process was used to synthesize a ZSM-5 molecular sieve (marked as Z5 (50)-700 nm) with a Si/Al molar ratio of 50 and an average particle size of 700 nm, comprising the steps of:

[0075] 0.41 g of aluminum isopropoxide was added to a mixed solution of 39.96 g of tetrapropylammonium hydroxide solution (25 wt %) and 17.89 g of deionized water. The mixture was placed and stirred at room temperature for 12 h, then 21.06 g of ethyl orthosilicate was added dropwise. After stirring for 12 h, 27.99 g ammonium bicarbonate was added to the mixed system and stirring was continued for 1 h. The mother liquor was transferred to a PTFE lined autoclave and hydrothermally treated in a 180 C. oven for 48 h. The liquor was centrifugally separated and repeatedly washed with deionized water until the supernatant was neutral, and dried to obtain a solid product, namely an uncalcined ZSM-5 sample, wherein an XRD spectrum thereof was shown in FIG. 2.

Example 1

[0076] 10 g of MnO prepared in Example a, 10 g of Z5(50)-450 nm prepared in Example b and 10 g of silica sol (with 4 g of SiO.sub.2 contained) were mechanically mixed, extruded into a strip shape, and crystallized in tetrapropylammonium hydroxide vapor at 170 C. for 48 hours. The crystallized catalyst was calcined at 550 C. for 5 hours to obtain catalyst SSL-1.

Example 2

[0077] 10 g of Cr.sub.2O.sub.3 prepared in Example c, 10 g of Z5(50)-450 nm prepared in Example b and 10 g of silica sol (with 4 g of SiO.sub.2 contained) were mechanically mixed, extruded into a strip shape, and crystallized in tetrapropylammonium hydroxide vapor at 170 C. for 48 hours. The crystallized catalyst was calcined at 550 C. for 5 hours to obtain catalyst SSL-2.

Example 3

[0078] 10 g of CrMnO.sub.x prepared in Example d, 10 g of Z5(50)-450 nm prepared in Example b and 10 g of silica sol (with 4 g of SiO.sub.2 contained) were mechanically mixed, extruded into a strip shape, and crystallized in tetrapropylammonium hydroxide vapor at 170 C. for 48 hours. The crystallized catalyst was calcined at 550 C. for 5 hours to obtain catalyst SSL-3.

Example 4

[0079] 10 g of Cr.sub.2O.sub.3 prepared in Example c, 10 g of Z11(50)-450 nm prepared in Example e and 10 g of silica sol (with 4 g of SiO.sub.2 contained) were mechanically mixed, extruded into a strip shape, and crystallized in tetrapropylammonium hydroxide vapor at 170 C. for 48 hours. The crystallized catalyst was calcined at 550 C. for 5 hours to obtain catalyst SSL-4.

Example 5

[0080] 10 g of Cr.sub.2O.sub.3 prepared in Example c, 10 g of Z5(50)-200 nm prepared in Example f and 10 g of silica sol (with 4 g of SiO.sub.2 contained) were mechanically mixed, extruded into a strip shape, and crystallized in tetrapropylammonium hydroxide vapor at 170 C. for 48 hours. The crystallized catalyst was calcined at 550 C. for 5 hours to obtain catalyst SSL-5.

Example 6

[0081] 10 g of Cr.sub.2O.sub.3 prepared in Example c, 10 g of Z5(50)-300 nm prepared in Example g and 10 g of silica sol (with 4 g of SiO.sub.2 contained) were mechanically mixed, extruded into a strip shape, and crystallized in tetrapropylammonium hydroxide vapor at 170 C. for 48 hours. The crystallized catalyst was calcined at 550 C. for 5 hours to obtain catalyst SSL-6.

Example 7

[0082] 10 g of Cr.sub.2O.sub.3 prepared in Example c, 10 g of Z5(50)-700 nm prepared in Example h and 10 g of silica sol (with 4 g of SiO.sub.2 contained) were mechanically mixed, extruded into a strip shape, and crystallized in tetrapropylammonium hydroxide vapor at 170 C. for 48 hours. The crystallized catalyst was calcined at 550 C. for 5 hours to obtain catalyst SSL-7. For the catalyst SSL-7, the XRD spectrum was shown in FIG. 1, the SEM photograph was shown in FIG. 3, and the scanning photograph was shown in FIG. 4.

Example 8

[0083] 10 g of Cr.sub.2O.sub.3 prepared in Example c, 10 g of Z5(50)-700 nm prepared in Example h and, and a mixture of silica sol and aluminum nitrate (with an equivalent total weight of SiO.sub.2 and Al.sub.2O.sub.3 of 4 g, a Si/Al ratio of 100) were mechanically mixed, extruded into a strip shape, and crystallized in tetrapropylammonium hydroxide vapor at 170 C. for 48 hours. The crystallized catalyst was calcined at 550 C. for 5 hours to obtain catalyst SSL-8.

Example 9

[0084] 20 g of Cr.sub.2O.sub.3 prepared in Example c, 10 g of Z5(50)-700 nm prepared in Example h and 10 g of silica sol (with 4 g of SiO.sub.2 contained) were mechanically mixed, extruded into a strip shape, and crystallized in tetrapropylammonium hydroxide vapor at 170 C. for 48 hours. The crystallized catalyst was calcined at 550 C. for 5 hours to obtain catalyst SSL-9.

Example 10

[0085] 10 g of Cr.sub.2O.sub.3 prepared in Example c, 10 g of Z5(50)-700 nm prepared in Example i and 10 g of silica sol (with 4 g of SiO.sub.2 contained) were mechanically mixed, extruded into a strip shape, and crystallized in tetrabutylammonium hydroxide vapor at 170 C. for 48 hours. The crystallized catalyst was calcined at 550 C. for 5 hours to obtain catalyst SSL-10.

Example 11

[0086] 10 g of Cr.sub.2O.sub.3 prepared in Example c, 10 g of Z5(50)-700 nm prepared in Example j and 10 g of silica sol (with 4 g of SiO.sub.2 contained) were mechanically mixed, extruded into a strip shape, and crystallized in ammonia vapor at 170 C. for 72 hours. The crystallized catalyst was calcined at 550 C. for 5 hours to obtain catalyst SSL-11.

Comparative Example 1

[0087] 10 g of Cr.sub.2O.sub.3 prepared in Example c, 10 g of Z5(50)-700 nm prepared in Example h were mechanically mixed. The XRD spectrum of the catalyst was shown in FIG. 1. Catalyst particles of 20-40 mesh were obtained from granulating and crushing.

Comparative Example 2

[0088] 10 g of Cr.sub.2O.sub.3 prepared in Example c, 10 g of Z5(50)-700 nm prepared in Example h and 10 g of silica sol (with 4 g of SiO.sub.2 contained) were mechanically mixed, and extruded into a strip shape, to obtain catalysts. XRD spectrum and SEM photograph of the catalysts were shown in FIGS. 1 and 3, respectively, from which the presence of amorphous silica was observed. A scanning photograph of the catalysts was shown in FIG. 5.

Comparative Example 3

[0089] 10 g of Cr.sub.2O.sub.3 prepared in Example c, 10 g of Z5(50)-700 nm prepared in Example h and 10 g of silica sol (with 4 g of SiO.sub.2 contained) were mechanically mixed, extruded into a strip shape, and crystallized in water vapour at 170 C. for 48 hours. The crystallized catalyst was calcined at 550 C. for 5 hours to obtain catalysts.

Characterization Example

[0090] The catalysts of some of the Examples according to the present invention and Comparative Examples were characterized and the results were illustrated below referring to FIGS. 1-5:

[0091] The XRD spectra of the catalyst SSL-7, the catalyst obtained in the Comparative Example 2 and the catalyst obtained in the Comparative Example 1 were respectively shown as panels (1), (2) and (3) in FIG. 1, and all had obvious ZSM-5 characteristic peaks, wherein the XRD spectrum of the catalyst SSL-7 did not substantially comprise a characteristic diffraction peak of amorphous silica, while a characteristic diffraction peak of the amorphous silica could be obviously seen from the XRD spectrum of the catalyst obtained in the Comparative Example 2. Furthermore, the characteristic peak intensity of ZSM-5 of the catalyst SSL-7 was higher than that of the catalyst obtained in the Comparative Example 2 and the catalyst obtained in the Comparative Example 1;

[0092] The XRD spectra of the molecular sieves obtained in the Examples b, f, g, h, i and j were respectively shown in panels (1), (2), (3), (4), (5) and (6) in FIG. 2, and all had obvious ZSM-5 characteristic peaks;

[0093] The SEM images of the catalyst of Comparative Example 2 and catalyst SSL-7 were shown in panels (1) and (2) of FIG. 3, respectively, and it could be seen from FIG. 3 that the catalyst of Comparative Example 2 had oxide grains and smaller binder particles dispersed on the surface of the molecular sieve grains, while the binder particles disappeared on the surface of the molecular sieve in catalyst SSL-7 but molecular sieves were formed;

[0094] A scanning photograph of catalyst SSL-7 was shown in FIG. 4, panel (1), wherein about 75% of the oxide was distributed on the surface of the molecular sieve. Less than 25% of the oxide was distributed in a range having a distance of more than 100 nm from the surface of the molecular sieve crystal grains. The nano-CT photographs of the crystal planes (100) and (010) of the molecular sieve were shown in panels (2) and (3) in FIG. 4, respectively. As could be seen from FIG. 4, panel (2), the oxide was selectively distributed mainly on the crystal plane (100) and the adjacent crystal plane (101) of the molecular sieve, while as could be seen from FIG. 4, panel (3), the distribution on the crystal plane (010) was less. Specifically, about 80% of the oxide was distributed on the crystal planes (100) and (101), and about 20% was distributed on the crystal plane (010). Accounting the weight of the metal oxide distributed in unit area on the crystal plane (010) of the molecular sieve as 1, the weight of the metal oxide distributed in unit area on the crystal plane (101) was more than 3.

[0095] The scanning photograph of the catalyst of Comparative Example 2 was shown in FIG. 5, panel (1), wherein the nano-CT photographs of crystal plane (100) and crystal plane (010) were respectively shown in FIG. 5, panels (2) and (3), and the distribution of the metal oxide on the surface of the molecular sieve did not show any selectivity, without the characteristics of distribution on any specific crystal plane.

EVALUATION A OF CATALYST PERFORMANCE

[0096] The catalysts of Examples 1 to 11 and Comparative Examples 1 to 3 were used to evaluate the performance thereof by taking 1.5 g of each catalyst. The catalyst was evaluated as follows: respectively weighing 1.5 g of the SSL 1-SSL 11 catalysts prepared in the Examples 1-11 or 1.5 g of the catalysts prepared in the Comparative Examples 1-3, crushing the catalysts to 20-40 meshes, and filling the crushed catalysts into a reactor. The catalyst evaluation was carried out at a reaction temperature of 395 C., a pressure of 6.0 MPa, a feed gas H.sub.2/CO ratio of 1.0 and a volume space velocity of 2000 h.sup.1. The catalyst was pretreated with H.sub.2 at 395 C. for 2 h before reaction. The raw material gases H.sub.2/CO/N.sub.2, and product were analyzed on line by gas chromatography, wherein the quantitative analysis of the products was realized by taking N.sub.2 as an internal standard. The products were separated by using three columns, wherein one column was a hayesep-Q packed column, where the separated products were introduced into a thermal conductivity cell detector for detecting hydrogen, nitrogen, carbon monoxide, carbon dioxide, methane and the like. Aliphatic hydrocarbons and aromatic hydrocarbons were cut by using the dean switch technology of Agilent, and detected respectively by two sets of hydrogen flame detectors, wherein one column was an HP-PLOT Al.sub.2N.sub.3 capillary column, and the products were fed to the hydrogen flame detectors to detect aliphatic hydrocarbon products such as methane, ethane, ethylene, propane, propylene, butane, butylene and the like; and the other column was a DB-WAXetr capillary column, and the products were fed to a hydrogen flame detector to detect aromatic hydrocarbon products such as benzene, toluene, xylene, C.sub.9+ aromatic hydrocarbons and the like. The results of CO conversion, selectivity to aromatics, and selectivity to C.sub.6-C.sub.8 aromatics were shown in Table 1.

EVALUATION B OF CATALYST PERFORMANCE

[0097] 1.5 g of the catalyst of Example 7 was used for performance evaluation. The catalyst evaluation process was as follows: 1.5 g of SSL7 catalyst prepared in Example 7 was weighed, crushed to 20-40 mesh and loaded into a reactor. Different reaction temperatures, pressures, feed gas compositions and volume space velocities were set, and catalyst evaluation was carried out under different conditions. The catalyst was pretreated with H.sub.2 at 395 C. for 2 h before reaction. The reaction conditions and the evaluation results (CO conversion, selectivity to aromatics, and selectivity to C.sub.6-C.sub.5 aromatics) were shown in Table 2.

TABLE-US-00001 TABLE 1 Molecular Weight ratio Selectivity sieves (Si/Al of metal CO Selectivity to C.sub.6-C.sub.8 Metal ratio) and oxide:molecular Crystallization Conversion to aromatics aromatics Catalyst Oxide particle size Binder sieve:binder method (%) (%) (%) SSL1 MnO Z5(50) Silica 1:1:0.4 TPAOH, 45 71 58 450 nm sol 170 C., 48 h SSL2 Cr.sub.2O.sub.3 Z5(50) Silica 1:1:0.4 TPAOH, 42 75 54 450 nm sol 170 C., 48 h SSL3 CrMnO.sub.x Z5(100) Silica 1:1:0.4 TPAOH, 40 74 56 450 nm sol 170 C., 48 h SSL4 Cr.sub.2O.sub.3 Z11(50) Silica 1:1:0.4 TPAOH, 40 70 51 450 nm sol 170 C., 48 h SSL5 Cr.sub.2O.sub.3 Z5(50) Silica 1:1:0.4 TPAOH, 45 73 24 200 nm sol 170 C., 48 h SSL6 Cr.sub.2O.sub.3 Z5(50) Silica 1:1:0.4 TPAOH, 43 73 35 300 nm sol 170 C., 48 h SSL7 Cr.sub.2O.sub.3 Z5(50) Silica 1:1:0.4 TPAOH, 41 74 58 700 nm sol 170 C., 48 h SSL8 Cr.sub.2O.sub.3 Z5(50) Silica 1:1:0.4 TPAOH, 44 75 53 700 nm sol + 170 C., 48 h aluminum nitrate (100:1) SSL9 Cr.sub.2O.sub.3 Z5(50) Silica 2:1:0.4 TPAOH, 38 72 57 700 nm sol 170 C., 48 h SSL10 Cr.sub.2O.sub.3 Z5(50) Silica 1:1:0.4 TBAOH, 40 76 56 700 nm sol 170 C., 48 h SSL11 Cr.sub.2O.sub.3 Z5(50) Silica 1:1:0.4 NH.sub.3H.sub.2O, 33 73 53 700 nm sol 170 C., 72 h Comparative Cr.sub.2O.sub.3 Z5(50) / 1:1 / 23 81 46 example 1 700 nm Comparative Cr.sub.2O.sub.3 Z5(50) Silica 1:1:0.4 / 18 75 52 example 2 700 nm sol Comparative Cr.sub.2O.sub.3 Z5(50) Silica 1:1:0.4 H.sub.2O, 31 72 49 example 3 700 nm sol 170 C., 48 h

TABLE-US-00002 TABLE 2 Space CO Selectivity Selectivity to H.sub.2/CO Temperature Pressure velocity Conversion to aromatics C.sub.6-C.sub.8 aromatics (mol/mol) ( C.) (MPa) (h.sup.1) (mol %) (mol %) (mol %) 1.0 350 8.0 8000 43 73 52 0.5 395 8.0 10000 38 75 53 4.0 350 5.0 15000 36 70 58 1.0 395 5.0 15000 37 79 57 1.0 450 5.0 15000 42 71 60 0.5 395 4.0 5000 40 76 54

[0098] The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including various technical features being combined in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.