CN110237859B

CN110237859B - Catalyst, preparation method and application thereof, and preparation method of 1,3-butadiene

Info

Publication number: CN110237859B
Application number: CN201810187120.5A
Authority: CN
Inventors: 王永睿; 李江成; 孙明毅; 陈俊文; 慕旭宏; 舒兴田
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2018-03-07
Filing date: 2018-03-07
Publication date: 2021-11-12
Anticipated expiration: 2038-03-07
Also published as: CN110237859A

Abstract

The invention relates to the field of catalysts, and discloses a catalyst, a preparation method and application thereof, and a preparation method of 1,3-butadiene, wherein the catalyst contains an EWT structure molecular sieve and a metal oxide. The preparation method of the 1,3-butadiene comprises the following steps: in the presence of a catalyst, ethanol and acetaldehyde are subjected to contact reaction, wherein the catalyst is provided by the invention. The invention adopts the molecular sieve which contains metal oxide and has a topological structure of an EWT structure as an active component of the catalyst for the first time, and the molecular sieve shows excellent catalytic performance when being applied to the reaction of preparing 1,3-butadiene from ethanol.

Description

Catalyst, preparation method and application thereof, and preparation method of 1,3-butadiene

Technical Field

The invention relates to a catalyst, a preparation method and application thereof, and a preparation method of 1,3-butadiene, in particular to a catalyst containing an EWT structure molecular sieve for synthesizing 1,3-butadiene, a preparation method and application thereof, and a method for preparing 1,3-butadiene by adopting the catalyst containing the EWT structure molecular sieve.

Background

Molecular sieves have a wide range of applications, and different applications often have special requirements on the pore structure of the molecular sieve. The molecular sieve is one of important catalytic materials and has wide application in the fields of oil refining and chemical industry. Molecular sieves include small, medium, large and ultra large pore types: the small pore molecular sieve has

The pore diameter of (1) comprises CHA, LEV, SOD, LTA, ERI, KFI; the mesoporous molecular sieve has

Pore sizes of (4) including MFI, MEL, EUO, MWW, TON, MTT, MFS, AEL, AFO, HEU, FER; the macroporous molecular sieve has

Including FAU, BEA, MOR, LTL, VFI, MAZ;

the pore diameter of (a). The ultra-large pore molecular sieve breaks through the pore channel limitation of the molecular sieve, has advantages in the aspects of improving the macromolecular reaction activity, prolonging the service life of the molecular sieve, improving the product selectivity and the like, and is expected to show application prospects in heavy oil processing and organic chemical raw material production.

Among the 232 molecular sieve structures at present, the ultra-large pore molecular sieve has only more than 10. Mainly comprises three types, namely phosphorus aluminum/gallium, silicon germanium/gallium and silicon aluminum molecular sieves: the aluminophosphate/gallium molecular sieve has the structure of AlPO-8(AET,14-ring,

)、VPI-5(VFI,18-ring,

)、Cloverite(-CLO,20-ring,

)、JDF-20(20-ring)、ND-1(24-ring,

) (ii) a The silicon germanium and silicon gallium molecular sieve has the structure of OSB-1(OSO,14-ring, Si/Be ═ 2,

) ECR-34(ETR,18-ring,10.5A, Si/Ga ═ 3), ITQ-37(30-ring), ITQ-43(28-ring), ITQ-33(18-ring), ITQ-44(18-ring), ITQ-40(16-ring) SSZ-53(14-ring), SSZ-59(14-ring), and the like; the silicon-aluminum molecular sieves are few in types, including UTD-1(DON,14-ring, Si/Al)₂＝∞,

) And CIT-5(CFI,14-ring,

Si/Al₂190) and the like.

Chinese patent application CN103842294A discloses the synthesis and use of EMM-23 molecular sieve materials, which uses bis (N-propylpyrrolidinium) pentane dication or bis (N-propylpyrrolidinium) hexane dication as template agent to synthesize molecular sieve (EMM-23) with three-dimensional 21-membered ring and 10-membered ring channel structure. The synthesis condition of the molecular sieve is n (SiO)₂)/n(Al₂O₃)＝100～150，n(H₂O)/n(SiO₂)＝2～10，n(OH^-)/n(SiO₂)＝0.2～0.5，n(R)/n(SiO₂) 0.1-0.25, and crystallizing at 150 ℃ for 6-10 days. The EMM-23 molecular sieve still has high specific surface area and thermal stability after being calcined at 540 ℃, and can be used for processes such as catalytic cracking, hydrocracking, disproportionation, alkylation, oligomerization and isomerization.

1,3-butadiene is an important petrochemical raw material and has wide application in the fields of synthetic rubber, synthetic resin and the like. Wherein the content of the first and second substances,in the synthetic rubber industry, 1,3-butadiene consumption accounts for 80% of the total 1,3-butadiene consumption worldwide. In recent years, the bioethanol production technology is rapidly developed, the sources of ethanol are gradually enriched, and particularly the development and maturity of the ethanol production technology of non-grain raw materials enable a technical route for synthesizing 1,3-butadiene from ethanol to have wide prospects. The synthesis of 1,3-butadiene from ethanol is a reaction process of dehydrogenation and dehydration, and requires a catalyst to have double functions of an acid center and a basic center, and the acid-base property of the catalyst determines the catalytic activity and selectivity of the catalyst. The catalyst for synthesizing 1,3-butadiene from ethanol is mainly mixed oxide, and the one-step catalyst mainly comprises ZnO/Al₂O₃Sepiolite and MgO/SiO₂And the catalyst in the two-step method is mainly Ta₂O₅/SiO₂，ZnO/Al₂O₃And the like. At present, the main problems of the reaction for preparing 1,3-butadiene from ethanol are that side reactions are more and the yield of butadiene is lower. From the catalyst perspective: 1) the catalyst selectivity is low, and reaction products are complex; 2) the reaction temperature is high, and the energy consumption is high; 3) the catalyst is easy to deposit carbon and deactivate, and has higher requirement on the concentration of the raw material ethanol. After a large amount of comparative screening is carried out on the traditional oxide catalyst, the space for improving the selectivity of the butadiene is not large. Therefore, it is considered to develop a novel catalyst suitable for the reaction.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides a catalyst containing an EWT structure molecular sieve, a preparation method and application thereof, and a method for preparing 1,3-butadiene by using the catalyst containing the EWT structure molecular sieve, wherein the catalyst shows excellent catalytic performance when being applied to ethanol preparation of 1, 3-butadiene.

In order to achieve the above object, the first aspect of the present invention provides a catalyst, wherein the catalyst comprises an EWT-structure molecular sieve and a metal oxide.

The second aspect of the present invention provides a method for preparing a catalyst, wherein the method for preparing the catalyst comprises: converting the EWT structure molecular sieve into an H-EWT molecular sieve, preparing the H-EWT molecular sieve with framework vacancies, dispersing the H-EWT molecular sieve with the framework vacancies into a solution containing a precursor of a metal oxide, and then removing a solvent and roasting.

The third aspect of the present invention provides a method for preparing a catalyst, wherein the method for preparing the catalyst comprises: converting the molecular sieve with the EWT structure into an H-EWT molecular sieve, contacting a solution of a precursor of a metal oxide with the H-EWT molecular sieve, and drying and roasting the contacted H-EWT molecular sieve.

In a fourth aspect, the invention provides the use of a catalyst according to the invention in a hydrocarbon conversion reaction, preferably in the synthesis of 1,3-butadiene, more preferably in the synthesis of 1,3-butadiene from ethanol.

The fifth aspect of the present invention provides a method for preparing 1,3-butadiene, wherein the method comprises: in the presence of a catalyst, ethanol and acetaldehyde are subjected to contact reaction, wherein the catalyst is provided by the invention.

The invention adopts the molecular sieve with the topological structure of the EWT structure as the main active component of the catalyst for the first time, so that the prepared catalyst has a super-macroporous structure, strong carbon-containing capacity, good hydrothermal stability and a certain amount of B acid centers, shows excellent catalytic performance when being applied to hydrocarbon conversion reaction, particularly to the reaction of preparing 1,3-butadiene from ethanol, and can obviously improve the conversion rate of ethanol and the selectivity of 1, 3-butadiene.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a scanning electron micrograph of a molecular sieve prepared in preparation example 1 of the present invention;

FIG. 2 is an XRD pattern of the molecular sieve prepared in preparative example 1 of the present invention;

FIG. 3 is a scanning electron micrograph of a molecular sieve prepared in preparation example 2 of the present invention;

FIG. 4 is an XRD pattern of the molecular sieve prepared in preparative example 2 of the present invention;

FIG. 5 is a scanning electron micrograph of a molecular sieve prepared in preparation example 3 of the present invention;

figure 6 is an XRD pattern of the molecular sieve prepared in preparative example 3 of the present invention.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

Technical terms in the present invention are defined in the following, and terms not defined are understood in the ordinary sense in the art.

According to the invention, the catalyst contains an EWT-structured molecular sieve and a metal oxide.

The EWT-structure molecular sieve is the first ultra-large pore structure silico-aluminum molecular sieve synthesized by ExxonMobil in 2012 (US20140336394a1), the structure of which is resolved in 2015, and the international molecular sieve structure committee (IZA) has externally published the structure of three-dimensional 10-membered ring and 21-membered ring for the first time.

According to the invention, the catalyst takes an EWT structure molecular sieve as an active component. In order to further improve the catalytic activity of the catalyst, the catalyst comprises an EWT-structure molecular sieve and a metal oxide, which may be a metal oxide conventionally used in the art, preferably, the metal oxide is an oxide of at least one metal selected from the group consisting of tantalum, zirconium, zinc and magnesium. The content of the EWT-structure molecular sieve and the metal oxide in the catalyst is not particularly limited, and the content of the EWT-structure molecular sieve and the content of the metal oxide in the catalyst are based on the catalytic effect. More preferably, the content of the EWT-structured molecular sieve is 95 to 99.9 wt% and the content of the metal oxide is 0.1 to 5 wt%, based on the total weight of the catalyst, and still more preferably, the content of the EWT-structured molecular sieve is 96 to 99 wt% and the content of the metal oxide is 1 to 4 wt%.

According to the invention, the silicon-aluminum ratio of the raw powder of the EWT structure molecular sieve is 30-700:1, and more preferably 40-500: 1.

According to the invention, in order to further improve the catalytic activity and selectivity of the catalyst, the EWT structure molecular sieve is an H-EWT (hydrogen EWT structure molecular sieve) molecular sieve having framework vacancies. It is further preferred that the framework vacancies of the H-EWT allow the metal oxides to be attached to the molecular sieve framework, thereby further improving the catalytic activity and selectivity of the catalyst.

The catalyst with the topological structure of the EWT structure molecular sieve as the main active component of the catalyst has a super-macroporous structure, strong carbon capacity and good hydrothermal stability, and the BET total specific surface area of the catalyst is S_{General assembly}＝450-600m²Per g, total pore volume V_{General assembly}＝0.25-0.4cm³/g。

According to the invention, the active component of the catalyst is the combination of the EWT structure molecular sieve and the metal oxide, and the catalyst of the invention can be prepared by referring to the conventional method in the field, for example, the catalyst can be prepared by the conventional impregnation method, for example, the dry impregnation method (i.e., the equivalent volume impregnation method) can be selected for preparation, and for example, the incipient wetness impregnation method can be selected for preparation. According to one embodiment of the present invention, the preparation of the catalyst may be carried out as follows: converting the molecular sieve with the EWT structure into an H-EWT molecular sieve, contacting a solution of a precursor of a metal oxide with the H-EWT molecular sieve, and drying and roasting the contacted H-EWT molecular sieve.

When the metal in the metal oxide is a plurality of elements, the method for contacting the solution of the metal oxide precursor with the H-EWT molecular sieve can be carried out according to the following two methods: (1) the solution of a plurality of metal oxide precursors can be prepared into a mixed solution and then contacted with the H-EWT molecular sieve; (2) the H-EWT molecular sieve can also be contacted with solutions of the various metal oxide precursors sequentially (the order of contacting with the solutions of the various metal oxide precursors can be selected arbitrarily).

According to the present invention, the conditions for the contact generally include a temperature and a time, the contact temperature may be 20 to 150 ℃, preferably 30 to 100 ℃, and the contact time may be appropriately selected according to the degree of dispersion of the metal oxide precursor, and preferably, the contact time is 1 to 5 hours. Furthermore, the amount of solvent in the solution of the precursor containing the metal oxide is such that, on the one hand, the precursor of the metal oxide is sufficiently soluble in the solvent and, on the other hand, sufficient dispersion of the molecular sieve is ensured, preferably the amount of solvent in the solution of the precursor containing the metal oxide is from 1 to 400ml, preferably from 1 to 200ml, based on the weight of the 1g H-EWT molecular sieve. The solvent may be at least one of water, ethanol, and propanol (including n-propanol and its isomer, isopropanol).

According to the invention, the amount of H-EWT molecular sieve and the precursor of metal oxide can be selected from a wide range, preferably, in order to further improve the catalytic performance of the catalyst, the amount of H-EWT molecular sieve and the precursor of metal oxide is such that the content of EWT structural molecular sieve is 95-99.9 wt% and the content of metal oxide is 0.1-5 wt% based on the total weight of the catalyst, preferably, the content of EWT structural molecular sieve is 96-99 wt% and the content of metal oxide is 1-4 wt% based on the total weight of the catalyst.

According to the present invention, after the solution of the precursor of the metal oxide is contacted with the H-EWT molecular sieve, the conditions for drying the H-EWT molecular sieve may be conventional drying conditions, for example, the drying temperature may be 80 to 120 ℃, and the drying time may be 2 to 10 hours.

According to the present invention, preferably, in order to further improve the catalytic activity and selectivity of the catalyst, the preparation method of the catalyst comprises: converting the EWT structure molecular sieve into an H-EWT molecular sieve, preparing the H-EWT molecular sieve with framework vacancies, dispersing the H-EWT molecular sieve with the framework vacancies into a solution containing a precursor of a metal oxide, and then removing a solvent and roasting. By preparing the H-EWT molecular sieve with framework vacancies, the high-dispersity metal oxide is connected to the framework of the molecular sieve, so that the catalytic activity and the selectivity of the catalyst are further improved.

Among them, the method for converting the EWT structure molecular sieve into the H-EWT molecular sieve can be performed with reference to a conventional method in the art. For example: performing ammonium salt exchange and deamination roasting on a molecular sieve (comprising EWT structure molecular sieve raw powder or a roasted EWT structure molecular sieve). Wherein the ammonium salt exchange conditions comprise: the temperature can be 70-90 ℃, the water-soluble ammonium salt used for ammonium salt exchange can be one or more selected from ammonium nitrate, ammonium chloride and ammonium sulfate, and the concentration of the ammonium salt aqueous solution is generally 1-10 mol/L. In addition, the number and time of ammonia exchange depends on the degree of exchange of sodium ions in the molecular sieve during actual operation.

The conditions of the deammoniation calcination in the conversion of the EWT-structured molecular sieve to the H-EWT molecular sieve according to the present invention generally include a calcination temperature, which may be 500 to 600 ℃, and a calcination time, which may be selected depending on the calcination temperature, and may generally be 2 to 8 hours. The calcination is generally carried out in an air atmosphere, which includes both a flowing atmosphere and a static atmosphere.

The main process for the preparation of H-EWT molecular sieves with framework vacancies according to the present invention can be referred to the post-treatment process of acid dealumination, which is conventional in the art. Wherein, the acid can be selected from one or more of nitric acid, sulfuric acid, hydrochloric acid and hydrofluoric acid, and the concentration range of the acid is usually 1-15 mol/L. In addition, the treatment conditions for the acid dealumination generally include treatment temperature and treatment time, the treatment temperature can be selected according to different acid types, and is generally 10 ℃ to 120 ℃, and the treatment time can be 1 hour to 24 hours.

According to the present invention, the conditions for the dispersion generally include temperature and time, the dispersion temperature may be 20 to 150 ℃, preferably 30 to 100 ℃, and the dispersion time may be appropriately selected according to the degree of dispersion, and preferably, the dispersion time is 1 to 5 hours. Furthermore, the amount of solvent in the solution of the precursor containing the metal oxide is such that, on the one hand, the precursor of the metal oxide is sufficiently soluble in the solvent and, on the other hand, sufficient dispersion of the molecular sieve is ensured, preferably the amount of solvent in the solution of the precursor containing the metal oxide is from 20 to 400ml, preferably from 50 to 200ml, based on 1g of the weight of the H-EWT molecular sieve having framework vacancies. The solvent may be at least one of water, ethanol, and propanol (including n-propanol and its isomer, isopropanol).

According to the present invention, the amount of the H-EWT molecular sieve having framework vacancies and the precursor of the metal oxide can be selected from a wide range, and preferably, in order to further improve the catalytic performance of the catalyst, the amount of the H-EWT molecular sieve having framework vacancies and the precursor of the metal oxide is such that the content of the EWT structural molecular sieve is 95 to 99.9 wt% and the content of the metal oxide is 0.1 to 5 wt%, based on the total weight of the catalyst, and preferably, the content of the EWT structural molecular sieve is 96 to 99 wt% and the content of the metal oxide is 1 to 4 wt%, based on the total weight of the catalyst.

Further, in view of the catalytic activity of the catalyst, the pH of the suspension obtained by dispersing the H-EWT molecular sieve having framework vacancies in the solution of the precursor containing the metal oxide is preferably weakly acidic or neutral, preferably 5.5 to 7, and more preferably 6 to 7.

According to the present invention, a method of dispersing the H-EWT molecular sieve having framework vacancies in a solution of a precursor containing a metal oxide, and then removing the solvent from the solution is well known to those skilled in the art, for example, a method of evaporation and/or drying (for example, the drying temperature can be 80 to 120 ℃, and the drying time can be 2 to 12 hours) can be used, and details thereof will not be described.

According to the present invention, the metal oxide precursor may be selected from one or more of soluble metal compounds; in the invention, the metal oxide precursor is selected from one or more soluble metal compounds of tantalum, zirconium, zinc and magnesium, the soluble metal compounds generally comprise water-soluble metal compounds and alcohol-soluble metal compounds, and specifically, the soluble metal compounds of zirconium, zinc and magnesium can be one or more of nitrates, chlorides and acetates of the metal; preferably one or more selected from the group consisting of zirconium chloride, zirconium nitrate, zinc chloride, magnesium chloride and magnesium nitrate. The soluble metal compound of tantalum may be one or more selected from organic salt compounds and/or inorganic salt compounds of tantalum such as tantalum ethoxide and tantalum chloride.

According to the present invention, the conditions for contacting a solution of a precursor of a metal oxide with the H-EWT molecular sieve and calcining the dried H-EWT molecular sieve, and the conditions for dispersing the H-EWT molecular sieve having framework vacancies in a solution of a precursor containing a metal oxide and removing the solvent and then calcining typically include a calcination temperature, which may be 400-700 ℃, and a calcination time, which may be selected according to the calcination temperature, and typically may be 2-8H. The calcination is generally carried out in an air atmosphere, which includes both a flowing atmosphere and a static atmosphere. Preferably, the method further comprises washing the obtained product before roasting, and the specific washing method is well known to those skilled in the art and is not described in detail.

The invention adopts the molecular sieve with the topological structure of the EWT structure as the main active component of the catalyst for the first time, so that the prepared catalyst has a super-macroporous structure, strong carbon-containing capacity, good hydrothermal stability and a certain amount of B acid centers, and therefore, the invention also provides the application of the catalyst in hydrocarbon conversion reaction, in particular the application in the reaction for preparing 1,3-butadiene from ethanol. In the application, the catalyst shows excellent catalytic performance, and can remarkably improve the conversion rate of ethanol and the selectivity of 1, 3-butadiene.

According to the present invention, the method for preparing 1,3-butadiene comprises: in the presence of a catalyst, ethanol and acetaldehyde are subjected to contact reaction, wherein the catalyst is provided by the invention. In the preparation method of 1,3-butadiene, the catalyst is the catalyst of the EWT structure molecular sieve containing the metal oxide, and the 1,3-butadiene can be produced from ethanol with high yield and high selectivity by applying the catalyst to the preparation of the 1,3-butadiene from the ethanol.

Since the improvement of the method for preparing 1,3-butadiene according to the present invention lies in the catalyst, the conditions for preparing 1,3-butadiene can be performed with reference to the prior art, and it is subject to the ability to prepare 1,3-butadiene from ethanol.

According to the invention, the conditions for the contact reaction of ethanol and acetaldehyde generally comprise reaction temperature and reaction pressure, wherein the reaction temperature can be maintained at 250-450 ℃, preferably at 250-400 ℃; the reaction pressure may be maintained at 0.1 to 4MPa, preferably 0.1 to 1.5 MPa. The object of the present invention can be achieved by using the catalyst of the present invention, the amount of which is set based on the total amount of ethanol and acetaldehyde so that the gas hourly space velocity of the reactants is from 0.1 to 9 hours, from the viewpoint of further improving the catalytic activity of the catalyst^-1(h^-1) Preferably 0.1 to 6 hours^-1(h^-1). The molar ratio of ethanol to acetaldehyde in the feed may be in the range of from 1 to 12, preferably from 2 to 5.

In the process of the present invention, the reaction raw materials are ethanol and acetaldehyde, wherein the acetaldehyde comprises pure acetaldehyde or dilute acetaldehyde, the dilute acetaldehyde raw material is a raw material containing low concentration acetaldehyde, and the mass percentage of acetaldehyde is generally 40-85 wt%.

In the process of the present invention, the reaction for producing 1,3-butadiene from ethanol may be carried out in various reactors conventionally used in the art, for example, including, but not limited to, at least one of a fixed bubble bed reactor, a fixed trickle bed reactor, and a slurry bed reactor.

The present invention will be described in detail below by way of examples.

In the following preparation examples, the specific surface area of the EWT-structured molecular sieve was measured according to the following analytical method:

equipment: micromeritic ASAP2010 static nitrogen adsorption apparatus.

Measurement conditions were as follows: the sample was placed in a sample handling system and evacuated to 1.33X 10 at 350 deg.C^-2Pa, keeping the temperature and the pressure for 15h, and purifying the sample. Measuring the P/P ratio of the purified sample at different specific pressures at a liquid nitrogen temperature of-196 DEG C₀And obtaining an adsorption-desorption isothermal curve for the adsorption quantity and the desorption quantity of the nitrogen under the condition. Then, the total specific surface area is calculated by utilizing a two-parameter BET formula, and the total pore volume is calculated as P/P₀Calculated as 0.98 adsorption.

In the following examples, a model 3013X-ray fluorescence spectrometer, manufactured by Nippon chemical Motor Co., Ltd., was used. And (3) testing conditions are as follows: tungsten target, excitation voltage 40kV, excitation current 50 mA. The experimental process comprises the following steps: the catalyst sample is pressed into a tablet and then arranged on an X-ray fluorescence spectrometer, and the catalyst sample emits fluorescence under the irradiation of X-rays, wherein the following relationship exists between the fluorescence wavelength lambda and the atomic number Z of the element: k (Z-S)^-2K is a constant, and the element can be determined by measuring the wavelength λ of fluorescence. And measuring the intensity of each element characteristic spectral line by using a scintillation counter and a proportional counter, and carrying out element quantitative or semi-quantitative analysis.

In the following examples, all reagents and starting materials are either commercially available or prepared according to established methods.

In the experimental examples, a fixed bed reactor was used to perform the process for preparing 1,3-butadiene from ethanol. The reactor is a stainless steel tube type isothermal reaction tube, the inner diameter is 12mm, the catalyst loading is 4g, ethanol and acetaldehyde (including dilute acetaldehyde, the concentration is 40 weight percent) are introduced from the top of the reaction tube, the material balance of the device is carried out, and the liquid yield is over 95 percent.

For convenience of expression, the following abbreviations are labeled: ethanol (EtOH), acetaldehyde (AA), unreacted ethanol (unreacted-EtOH), and unreacted acetaldehyde (unreacted-AA).

The ethanol conversion and 1,3-butadiene selectivity were calculated from the following equations:

wherein n is the mass percentage of each component in the product.

Preparation example 1

0.268g of sodium metaaluminate is placed in a 45mL Teflon container and 15.5g of template R (1, 5-bis (N-propylpyrrolidinium) pentane dihydrogenhydride is addedOxide) (content of R is 30% by mass), stirred for 30 minutes until uniform, and then 6g of solid silica gel (SiO) was added₂Content 98.05 mass%) and 17.5g of deionized water, and stirring for 5 minutes to fully mix, wherein the molar ratio of each component is as follows: SiO 2₂/Al₂O₃＝60、H₂O/SiO ₂10, template agent R/SiO₂＝0.16、OH^-/SiO₂＝0.32。

The above mixture was charged into a 45mL Teflon-lined steel autoclave which was covered and sealed, and the autoclave was placed in a rotating convection oven set at 20rpm and reacted at 150 ℃ for 5 days. And taking out the high-pressure autoclave, rapidly cooling the high-pressure autoclave to room temperature, separating the mixture on a high-speed centrifuge with the rpm of 5000, collecting solids, fully washing the solids with deionized water, and drying the solids for 5 hours at the temperature of 100 ℃ to obtain the raw powder of the molecular sieve with the EWT structure. The scanning electron microscope image of the product is shown in figure 1, the XRD image is shown in figure 2, and the silicon-aluminum ratio of the raw powder sample obtained by adopting X-ray fluorescence spectrum analysis is 50. The total specific surface area of the EWT structure molecular sieve is S_{General assembly}＝525m²Per g, total pore volume V_{General assembly}＝0.352cm³/g。

Preparation example 2

The raw powder of the molecular sieve with the EWT structure is prepared according to the method of the preparation example 1, except that the feeding amount of sodium metaaluminate is 0.107g, the types and the feeding amounts of other materials are the same as the preparation example 1, wherein the molar ratio of each component is as follows: SiO 2₂/Al₂O₃＝120、H₂O/SiO ₂10, template agent R/SiO₂＝0.16、OH^-/SiO₂0.32. Finally, the raw powder of the molecular sieve with the EWT structure is prepared. The scanning electron microscope image of the product is shown in figure 3, the XRD image is shown in figure 4, and the silicon-aluminum ratio of the raw powder sample obtained by adopting X-ray fluorescence spectrum analysis is 98. The total specific surface area of the EWT structure molecular sieve is S_{General assembly}＝601m²Per g, total pore volume V_{General assembly}＝0.386cm³/g。

Preparation example 3

A raw powder of an EWT structure molecular sieve was prepared according to the method of preparation example 1, except that the amount of sodium metaaluminate charged was 0g, and the types and charges of other materialsThe amount is the same as that of preparation example 1, wherein the molar ratio of each component is as follows: h₂O/SiO ₂10, template agent R/SiO₂＝0.15、OH^-/SiO₂0.08. Finally, the raw powder of the molecular sieve with the EWT structure is prepared. The scanning electron microscope image of the product is shown in fig. 5, the XRD image is shown in fig. 6, and the silicon-aluminum ratio of the raw powder sample obtained by adopting X-ray fluorescence spectrum analysis is 530. The total specific surface area of the EWT structure molecular sieve is S_{General assembly}＝580m²Per g, total pore volume V_{General assembly}＝0.321cm³/g。

Example 1

This example illustrates the preparation of a Ta-EWT catalyst.

The raw powder (SiO) of the EWT structure molecular sieve synthesized in preparation example 1₂/Al₂O₃50) with 1.5mol/L NH at 80 ℃₄Mixing Cl solution, continuously stirring for 2 hours, filtering, washing by distilled water, drying for 24 hours at 100 ℃, roasting for 4 hours at 550 ℃, removing organic template agent and ammonia (ignition weight loss is 15.7 percent), reacting with 13mol/L HNO at 80 DEG C₃The solutions were mixed and treated for 4 hours. Recovering by filtration to obtain H-EWT (SiO) with framework vacancies₂/Al₂O₃150), washed with distilled water, and dried at 80 ℃ for 24 hours. To introduce metals into the framework vacancies of an EWT molecular sieve, 2.0g of H-EWT having framework vacancies was contacted with a solution containing 3.3X 10 at 80 deg.C^-3mol/L of Ta (OC)₂H₅)₅(Acros Organic, 99.99%) in 100mL of isopropanol and stirred continuously for 3 hours. The suspension (pH 6.8) was then evaporated on a rotary distiller for 2h until the isopropanol evaporation was complete. The resulting solid was washed three times in distilled water and dried in air at 80 ℃ for 24 hours, and finally calcined in flowing air at 450 ℃ for 3 hours. The sample was designated Ta-EWT-60. The content of the EWT-structure molecular sieve was 96.5%, and the content of tantalum pentoxide was 3.5% by weight. The total specific surface area of the Ta-EWT-60 structure molecular sieve is S_{General assembly}＝508m²Per g, total pore volume V_{General assembly}＝0.322cm³/g。

Example 2

This example illustrates the preparation of a Ta-EWT catalyst.

The raw powder (SiO) of the EWT molecular sieve synthesized in preparation example 2 was added₂/Al₂O₃98) with 1.5mol/L NH at 80 ℃₄Mixing Cl solution, continuously stirring for 2 hours, filtering, washing by distilled water, drying for 24 hours at 100 ℃, roasting for 4 hours at 550 ℃, removing organic template agent and ammonia (ignition weight loss is 16.2 percent), reacting with 13mol/L HNO at 80 DEG₃The solutions were mixed and treated for 4 hours. Recovering by filtration to obtain H-EWT (SiO) with framework vacancies₂/Al₂O₃1900), washed with distilled water and dried at 353K for 24 hours. To introduce metals into the framework vacancies of an EWT molecular sieve, 2.0g of H-EWT having framework vacancies was contacted with a solution containing 3.3X 10 at 80 deg.C^-3mol/L of Ta (OC)₂H₅)₅(Acros Organic, 99.99%) in 100mL of isopropanol and stirred continuously for 3 hours. The suspension (pH 6.8) was then evaporated in a rotary distiller until the isopropanol evaporation was complete. The resulting solid was washed three times in distilled water and dried in air at 80 ℃ for 24 hours, and finally calcined in flowing air at 450 ℃ for 3 hours. The sample was designated Ta-EWT-120. The content of the EWT-structure molecular sieve was 96.5 wt%, and the content of tantalum pentoxide was 3.5 wt%. The total specific surface area of the Ta-EWT-120 structure molecular sieve is S_{General assembly}＝560m²Per g, total pore volume V_{General assembly}＝0.310cm³/g。

Example 3

This example serves to illustrate the preparation of a Zr-EWT catalyst.

The raw powder (SiO) of the EWT molecular sieve synthesized in preparation example 2 was added₂/Al₂O₃98) with 1.5mol/L NH at 80 ℃₄Mixing Cl solution, continuously stirring for 2 hours, filtering, washing by distilled water, drying for 24 hours at 100 ℃, roasting for 4 hours at 550 ℃, removing organic template agent and ammonia (ignition weight loss is 16.2 percent), reacting with 13mol/L HNO at 80 DEG₃The solutions were mixed and treated for 4 hours. Recovering by filtration to obtain H-EWT (SiO) with framework vacancies₂/Al₂O₃1900), washed with distilled water, and dried at 80 ℃ for 24 hours. To introduce metal into the framework vacancies of the EWT molecular sieve, 2.0g of a zeolite havingH-EWT with framework vacancy at 80 ℃ and H-EWT with 3.3X 10^-3mol/L ZrCl₄(Alfa Aesar, 99.99%) in 100ml of ethanol, and the mixture was stirred continuously for 3 hours. The suspension (pH 6.8) was then evaporated in a rotary distiller until the ethanol evaporation was complete. The resulting solid was washed three times in distilled water and dried in air at 80 ℃ for 24 hours, and finally calcined in flowing air at 450 ℃ for 3 hours. The sample was designated as Zr-EWT-120. The content of the molecular sieve having an EWT structure was 96.0% by weight, and the content of zirconium dioxide was 4.0% by weight. The total specific surface area of the molecular sieve with the Zr-EWT-120 structure is S_{General assembly}＝556m²Per g, total pore volume V_{General assembly}＝0.305cm³/g。

Example 4

This example serves to illustrate the preparation of a Zr-EWT catalyst.

The raw powder (SiO) of the EWT molecular sieve synthesized in preparation example 3 was added₂/Al₂O₃530) at 80 ℃ with 1.5mol/LNH₄Mixing Cl solution, continuously stirring for 2 hours, filtering, washing by distilled water, drying for 24 hours at 100 ℃, roasting for 4 hours at 550 ℃, removing organic template agent and ammonia (ignition weight loss is 16.0 percent), reacting with 13mol/L HNO at 80 DEG₃The solutions were mixed and treated for 4 hours. Recovering by filtration to obtain H-EWT (SiO) with framework vacancies₂/Al₂O₃2300), washed with distilled water, and dried at 80 ℃ for 24 hours. To introduce metals into the framework vacancies of an EWT molecular sieve, 2.0g of H-EWT having framework vacancies was contacted with a solution containing 3.3X 10 at 80 deg.C^-3mol/L ZrCl₄(Alfa Aesar, 99.99%) was mixed with 100mL of an ethanol solution and stirred continuously for 3 hours. The suspension (pH 6.8) was then evaporated in a rotary distiller until the ethanol evaporation was complete. The resulting solid was washed three times in distilled water and dried in air at 80 ℃ for 24 hours, and finally calcined in flowing air at 450 ℃ for 3 hours. The sample was designated as Zr-EWT-600. The content of the molecular sieve having an EWT structure was 96.0% by weight, and the content of zirconium dioxide was 4.0% by weight. The total specific surface area of the molecular sieve with the Zr-EWT-600 structure is S_{General assembly}＝528m²Per g, total pore volume V_{General assembly}＝0.282cm³/g。

Example 5

This example illustrates the preparation of a Zn-EWT catalyst

The raw powder (SiO) of the EWT molecular sieve synthesized in preparation example 2 was added₂/Al₂O₃98) with 1.5mol/L NH at 80 ℃₄Mixing Cl solution, continuously stirring for 2 hours, filtering, washing by distilled water, drying for 24 hours at 100 ℃, roasting for 4 hours at 550 ℃, removing organic template agent and ammonia (ignition weight loss is 16.2 percent), reacting with 13mol/L HNO at 80 DEG₃The solutions were mixed and treated for 4 hours. Recovering by filtration to obtain H-EWT (SiO) with framework vacancies₂/Al₂O₃1900), washed with distilled water, and dried at 80 ℃ for 24 hours. To introduce metals into the framework vacancies of an EWT molecular sieve, 2.0g of H-EWT having framework vacancies was contacted with a solution containing 3.3X 10 at 80 deg.C^-3mol/L of Zn (NO)₃)₂(national chemical Co., Ltd., 99.0%) of 100ml of an ethanol solution were mixed and stirred continuously for 3 hours. The suspension (pH 6.8) was then evaporated in a rotary distiller until the ethanol evaporation was complete. The resulting solid was washed three times in distilled water and dried in air at 80 ℃ for 24 hours, and finally calcined in flowing air at 450 ℃ for 3 hours. The sample was designated as Zn-EWT-120. The content of the molecular sieve having an EWT structure was 96.1% by weight, and the content of zirconium dioxide was 3.9% by weight. The total specific surface area of the molecular sieve with the Zn-EWT-120 structure is S_{General assembly}＝532m²Per g, total pore volume V_{General assembly}＝0.294cm³/g。

Example 6

This example illustrates the preparation of a Zr-EWT catalyst using an isometric impregnation method.

The raw powder (SiO) of the EWT molecular sieve synthesized in preparation example 2 was added₂/Al₂O₃98)2.0g, at 80 ℃ with 1.5mol/LNH₄Cl solution is mixed, continuously stirred for 2 hours, filtered, washed by distilled water, dried for 24 hours at 100 ℃, roasted for 4 hours at 550 ℃, and removed organic template agent and ammonia (ignition weight loss 16.0 wt%). 2.0H-EWT was weighed at 25 ℃ together with 4.3ml of Zr (SO) containing 0.06g of Zr₄)₂(aladdin, 99.99%) aqueous solution for 2 hours, etcVolume impregnation, drying at constant temperature of 100 ℃ for 24 hours, and roasting in flowing air at 450 ℃ for 3 hours. The sample was designated as Zr-EWT-120-impregnation. The content of the molecular sieve having an EWT structure was 95.8% by weight, and the content of zirconium dioxide was 4.2% by weight. The total specific surface area of the Zr-EWT-120-impregnated structure molecular sieve is S_{General assembly}＝493m²Per g, total pore volume V_{General assembly}＝0.270cm³/g。

Example 7

This example illustrates the preparation of a low metal content Ta-EWT catalyst.

The raw powder (SiO) of the EWT molecular sieve synthesized in preparation example 2 was added₂/Al₂O₃98) with 1.5mol/L NH at 80 ℃₄Mixing Cl solution, continuously stirring for 2 hours, filtering, washing by distilled water, drying for 24 hours at 100 ℃, roasting for 4 hours at 550 ℃, removing organic template agent and ammonia (ignition weight loss is 16.2 percent), reacting with 13mol/L HNO at 80 DEG₃The solutions were mixed and treated for 4 hours. Recovering by filtration to obtain H-EWT (SiO) with framework vacancies₂/Al₂O₃1900), washed with distilled water and dried at 353K for 24 hours. To introduce metals into the framework vacancies of an EWT molecular sieve, 2.0g of H-EWT having framework vacancies was contacted with a solution containing 1.5X 10^-3mol/L of Ta (OC)₂H₅)₅(Acros Organic, 99.99%) in 100mL of isopropanol and stirred continuously for 3 hours. The suspension (pH 6.8) was then evaporated in a rotary distiller until the isopropanol evaporation was complete. The resulting solid was washed three times in distilled water and dried in air at 80 ℃ for 24 hours, and finally calcined in flowing air at 450 ℃ for 3 hours. Sample Ta_1.5-EWT-120. The content of the EWT-structure molecular sieve was 98.8 wt%, and the content of tantalum pentoxide was 1.2 wt%. Said Ta_1.5Total specific surface area of molecular sieve of structure-EWT-120 is S_{General assembly}＝570m²Per g, total pore volume V_{General assembly}＝0.318cm³/g。

Comparative example 1

This comparative example serves to illustrate the preparation of a Ta-ZSM-5 containing catalyst.

A catalyst was prepared in accordance with the procedure of example 1Except that ZSM-5 molecular sieve raw powder (SiO)₂/Al₂O₃30) with 1.5mol/L NH at 80 ℃₄Mixing Cl solution, continuously stirring for 2 hours, filtering, washing by distilled water, drying for 24 hours at 100 ℃, roasting for 4 hours at 550 ℃, removing organic template agent and ammonia (ignition weight loss is 18 weight percent), and reacting with 13mol/L HNO at 80 DEG C₃The solutions were mixed and treated for 4 hours. Recovering by filtration to obtain H-EWT (SiO) with framework vacancies₂/Al₂O₃500), washed with distilled water, and dried at 80 ℃ for 24 hours. To introduce metal into the framework vacancies of the ZSM-5 molecular sieve, 2.0g of H-ZSM-5 having framework vacancies was contacted at 80 ℃ with a catalyst containing 3.3X 10^-3mol/L of Ta (OC)₂H₅)₅(Acros Organic, 99.99%) in 100ml of isopropanol and stirring was continued for 3 hours. The suspension (pH 6.8) was then evaporated in a rotary distiller until the isopropanol evaporation was complete. The resulting solid was washed three times in distilled water and dried in air at 80 ℃ for 24 hours, and finally calcined in flowing air at 450 ℃ for 3 hours. The sample was designated Ta-ZSM-30.

Comparative example 2

This comparative example serves to illustrate the prior art MgO/SiO₂And (3) preparing a catalyst.

This comparative example is described in Kvisole S, Aguero A, Sneeden R P. transformation of ethanol endo 1,3-butadiene over magnesium oxide/silica catalysts [ J]Preparation of MgO/SiO by the method of Applied Catalysis,1988,43(1):117-₂A catalyst.

Comparative example 3

This comparative example serves to illustrate the preparation of a catalyst comprising H-EWT-120.

The raw powder of the EWT structure molecular sieve with the silicon-aluminum ratio of 98 is prepared according to the method of preparation example 2. Weighing 2.0g of molecular sieve raw powder with an EWT structure, adding 20mL of ammonium chloride solution (1.5mol/L), mixing and stirring for 2H, washing with distilled water, filtering, recovering, drying in air at 80 ℃ for 24H, and finally roasting the obtained solid in flowing air at 450 ℃ for 3H, wherein the sample is recorded as H-EWT-120.

Experimental examples

This experimental example is intended to illustrate the process for preparing 1,3-butadiene from ethanol according to the present invention.

The catalysts prepared in examples 1 to 7 and comparative examples 1 to 3 were used in the reaction for preparing 1,3-butadiene from ethanol, respectively, and the results of the catalytic performance are shown in table 1.

The evaluation device is a fixed bed reactor, and the evaluation conditions are as follows: based on ethanol and acetaldehyde mixture as reactants, gas hourly space velocity: 1.4h^-1(ii) a Carrier gas flow: 300ml/min, reaction temperature: 325 ℃, reaction pressure: 0.6MPa, catalyst loading: 4.0 g. Ethanol and 40 wt% acetaldehyde solution are used as raw materials, wherein the molar ratio of ethanol to acetaldehyde is 2: 1.

TABLE 1

As can be seen from the results in Table 1, when the catalyst prepared by using the EWT molecular sieve of the invention is applied to the reaction for preparing 1,3-butadiene from ethanol, the selectivity of butadiene is obviously better than that of the comparative example, although the ethanol-acetaldehyde conversion rate of the comparative example is higher, ethylene is converted, and the yield of butadiene is very low, thereby showing that the catalyst provided by the invention has good catalytic performance. The combination of the preferred metal oxide and the EWT structure molecular sieve is used as the active component of the catalyst, and the selectivity of butadiene is better. Furthermore, as can be seen from a comparison of example 6 with example 3, the framework vacancies of H-EWT enable the metal oxide to be highly dispersed and attached to the molecular sieve framework, thereby further improving the catalytic activity and selectivity of the catalyst, in the catalyst prepared by the preferred preparation method of the present invention.

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 combinations of various technical features 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.

Claims

1. A catalyst comprising a molecular sieve having an EWT structure and a metal oxide, wherein the metal oxide is an oxide of at least one metal selected from the group consisting of tantalum, zirconium, zinc and magnesium.

2. The catalyst of claim 1, wherein the metal oxide is an oxide of tantalum and/or zirconium.

3. The catalyst of claim 1, wherein the EWT structure molecular sieve raw powder has a silicon to aluminum ratio of 30-700: 1.

4. The catalyst of claim 3, wherein the raw powder of the EWT structured molecular sieve has a silicon to aluminum ratio of 40-500: 1.

5. The catalyst of claim 3, wherein the EWT structure molecular sieve is an H-EWT molecular sieve.

6. The catalyst of claim 5, wherein the EWT structure molecular sieve is an H-EWT molecular sieve having framework vacancies.

7. The catalyst of any one of claims 1 to 6, wherein the EWT structure molecular sieve is present in an amount of 95 to 99.9 wt% and the metal oxide is present in an amount of 0.1 to 5 wt%, based on the total weight of the catalyst.

8. The catalyst of claim 7, wherein the EWT structure molecular sieve is present in an amount of 96 to 99 wt% and the metal oxide is present in an amount of 1 to 4 wt%.

9. The catalyst according to any one of claims 1 to 6, wherein the catalyst has a BET total specific surface area of S_{General assembly}＝450-600m²Per g, total pore volume V_{General assembly}＝0.25-0.4cm³/g。

10. A method for preparing a catalyst, comprising: converting the EWT structure molecular sieve into an H-EWT molecular sieve, preparing the H-EWT molecular sieve with framework vacancies, dispersing the H-EWT molecular sieve with the framework vacancies into a solution containing a precursor of a metal oxide, and then removing a solvent and roasting;

the metal in the precursor of the metal oxide is selected from at least one of tantalum, zirconium, zinc and magnesium.

11. The production method according to claim 10, wherein the conditions for dispersion include: the temperature is 20-150 ℃, the time is 1-5 hours, the dosage of the solvent in the solution containing the precursor of the metal oxide is 20-400ml based on the weight of 1g of H-EWT molecular sieve with framework vacancy, and the solvent is at least one of water, ethanol and propanol.

12. The process of claim 11, wherein the solvent is used in an amount of 50 to 200ml in the solution containing the precursor of the metal oxide, based on 1g of the H-EWT molecular sieve having framework vacancies.

13. The production method according to claim 10, wherein a pH of a suspension obtained by dispersing the H-EWT molecular sieve having framework vacancies in a solution containing a precursor of a metal oxide is 5.5 to 7.

14. The production method according to claim 13, wherein a pH of a suspension obtained by dispersing the H-EWT molecular sieve having framework vacancies in a solution containing a precursor of a metal oxide is 6 to 7.

15. The preparation method of claim 10, wherein the H-EWT molecular sieve having framework vacancies and the precursor of the metal oxide are used in amounts such that the content of the EWT structural molecular sieve is 95 to 99.9 wt% and the content of the metal oxide is 0.1 to 5 wt%, based on the total weight of the catalyst.

16. The method of claim 15, wherein the EWT-structured molecular sieve is contained in an amount of 96 to 99 wt% and the metal oxide is contained in an amount of 1 to 4 wt%, based on the total weight of the catalyst.

17. A method for preparing a catalyst, comprising: converting an EWT structure molecular sieve into an H-EWT molecular sieve, contacting a solution of a precursor of a metal oxide with the H-EWT molecular sieve, and drying and roasting the contacted H-EWT molecular sieve;

18. The method of claim 17, wherein the contacting conditions comprise: the temperature is 20-150 ℃, the time is 1-5 hours, and the dosage of the solvent in the solution of the precursor containing the metal oxide is 1-400ml based on the weight of the 1g H-EWT molecular sieve; the solvent is at least one of water, ethanol and propanol.

19. The method of claim 17, wherein the solvent is used in an amount of 1 to 200ml based on the weight of 1g H-EWT molecular sieve in the solution containing the precursor of the metal oxide.

20. The method of claim 17, wherein the H-EWT molecular sieve and the metal oxide precursor are used in amounts such that the EWT structural molecular sieve is present in an amount of 95 to 99.9 wt% and the metal oxide is present in an amount of 0.1 to 5 wt%, based on the total weight of the catalyst.

21. The method of claim 20, wherein the EWT-structured molecular sieve is contained in an amount of 96 to 99 wt% and the metal oxide is contained in an amount of 1 to 4 wt%, based on the total weight of the catalyst.

22. The production method according to any one of claims 10 to 16 and 17 to 21, wherein the metal in the precursor of the metal oxide is tantalum and/or zirconium.

23. The method of claim 10 or 17, wherein the roasting temperature is 400-700 ℃ and the roasting time is 2-8 h.

24. Use of a catalyst according to any one of claims 1 to 9 or prepared according to the preparation process of any one of claims 10 to 23 in a hydrocarbon conversion reaction.

25. Use of a catalyst according to any one of claims 1 to 9 or prepared according to the preparation process of any one of claims 10 to 23 for the synthesis of 1, 3-butadiene.

26. Use of the catalyst according to any one of claims 1 to 9 or the catalyst prepared by the preparation method according to any one of claims 10 to 23 for the synthesis of 1,3-butadiene from ethanol.

27. A method for preparing 1,3-butadiene, which is characterized by comprising the following steps: contacting ethanol and acetaldehyde in the presence of a catalyst, wherein the catalyst is the catalyst as claimed in any one of claims 1 to 9 or the catalyst prepared by the preparation method as claimed in any one of claims 10 to 23.

28. The process of claim 27, wherein the conditions for contacting ethanol and acetaldehyde comprise: the reaction temperature is 250 ℃ and 450 ℃, and the reaction pressure is 0.1-4 MPa.

29. The method of claim 28, wherein the conditions for contacting ethanol and acetaldehyde comprise: the reaction temperature is 250-400 ℃; the reaction pressure is 0.1-1.5 MPa.

30. The production method according to any one of claims 27 to 29, wherein the molar ratio of ethanol to acetaldehyde is 1 to 12, and the amount of the catalyst is set based on the total amount of ethanol and acetaldehyde so that the gas hourly space velocity of the reactants is 0.1 to 9h^-1。

31. The method of claim 30, wherein the molar ratio of ethanol to acetaldehyde is 2-5; and the amount of the catalyst is set based on the total amount of ethanol and acetaldehyde so that the gas hourly space velocity of the reactants is from 0.1 to 6h^-1。