Catalyst for preparing alcohol by light-driven shale gas oxidation as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for preparing alcohol through light-driven shale gas oxidation and a preparation method and application of the catalyst, the catalyst comprises a carrier and nickel clusters loaded on the carrier, and the carrier is a zinc oxide nanometer net. According to the catalyst disclosed by the invention, Ni-O-Zn sites are introduced to an interface of a nickel cluster and a zinc oxide nano-net, so that strong metal-semiconductor interaction is formed, electron-rich nickel clusters and electron-deficient oxygen vacancies are induced to form, separation and migration of photon-generated carriers are promoted, methyl, ethyl and isopropyl intermediates in the reaction process are stabilized, and the reaction efficiency is improved. The photocatalytic activity is obviously enhanced; the catalyst provided by the invention has wide substrate applicability, and simultaneous photooxidation of methane, ethane and propane is realized for the first time; the catalyst provided by the invention can catalyze the photo-oxidation of methane, ethane, propane and shale gas under the mild conditions of normal temperature and low oxygen concentration, reduce the degree of peroxidation and improve the selectivity of a target product.

Description

Technical Field

[0001] The present application belongs to the field of catalyst technology, and specifically relates to a catalyst for light-driven shale gas oxidation to alcohol, and its preparation method and application. Background Art

[0002] As shale gas (a mixture of methane, ethane, and propane) extraction becomes a key resource development priority, the supply of hydrocarbon feedstocks has increased significantly. This makes it possible to produce high-value-added chemicals from non-petroleum feedstocks, effectively alleviating the current energy and environmental crises. Consequently, academic and industrial interest in converting shale gas into high-value-added liquid chemicals is growing. Currently, shale gas is primarily converted to high-value-added chemicals through indirect pathways. These pathways include steam reforming of methane to produce syngas or steam cracking of ethane / propane to produce olefins, followed by conversion of the syngas or olefins into liquid chemicals such as alcohols, acids, and aldehydes. However, these thermochemical processes are not only energy-intensive but also difficult to control in terms of selectivity. Furthermore, some reactions require the use of corrosive solvents and / or additional oxidants, inevitably increasing costs and safety concerns. Therefore, directly converting shale gas to high-value-added products under mild conditions is of great industrial significance. However, this process still faces significant chemical challenges.

[0003] Solar-driven photoactivation of alkanes offers a promising avenue for sustainable chemical production. Studies have demonstrated that excited electron-hole pairs can achieve CH functionalization. Furthermore, the low temperatures required for photoconversion prevent catalyst sintering and product overoxidation. Current research on photochemical alkane conversion primarily focuses on single alkanes such as methane, ethane, or propane. There are no reports on the photooxidation of multiple alkanes or multicomponent shale gas, which are closer to practical applications and more meaningful. The main challenges of this technology are: i) how to regulate the selectivity of diverse liquid chemicals (such as acids, alcohols, and aldehydes); ii) how to simultaneously control CH and CC activation; and iii) how to prevent overoxidation in highly oxidizing environments. To address this issue, it is crucial to develop a photocatalyst system that can efficiently photooxidize multiple light alkanes without or with minimal external oxidants. Summary of the Invention

[0004] The purpose of this application is to provide a catalyst for light-driven shale gas oxidation to alcohol, its preparation method and application, so as to solve the technical problem that the catalysts in the prior art can only catalyze the oxidation of a single alkane and cannot be applied to the photooxidation of multiple alkanes or multi-component shale gas.

[0005] In order to achieve the above-mentioned objectives, the first aspect of the present application provides a catalyst for light-driven shale gas oxidation to alcohol, comprising a carrier and nickel clusters supported on the carrier, wherein the carrier is a zinc oxide nanomesh.

[0006] In one or more embodiments, Ni—O—Zn bonds exist at the interface between the nickel clusters and the zinc oxide nanomesh.

[0007] In one or more embodiments, the atomic percentage of the nickel clusters in the catalyst is 1.4 to 1.8 at %.

[0008] Preferably, the atomic percentage of the nickel clusters in the catalyst is 1.6 at %.

[0009] In order to achieve the above object, the second aspect of the present application provides a method for preparing the catalyst described in any one of the above embodiments, comprising:

[0010] Dissolving zinc salt and nickel salt in water to obtain solution I;

[0011] Dissolve urea in water to obtain solution II;

[0012] The solution I is continuously stirred, and during the stirring process, the solution II is added dropwise to the solution I to obtain a mixed solution;

[0013] performing a hydrothermal reaction on the mixed solution, collecting the precipitate by filtration, and then washing and drying to obtain an intermediate product;

[0014] The intermediate product is calcined at high temperature to obtain the catalyst.

[0015] In one or more embodiments, the molar ratio of zinc ions to nickel ions in the solution I is 10:(0.09-0.11).

[0016] In one or more embodiments, the molar ratio of urea to nickel ions in the mixed solution is 35:(0.0875-0.1125).

[0017] In one or more embodiments, the zinc salt is zinc acetate, and the nickel salt is nickel acetate.

[0018] In one or more embodiments, the hydrothermal reaction temperature is 100-120° C., and the time is 10-14 hours.

[0019] In one or more embodiments, the high temperature calcination temperature is 480-520°C, the time is 10-14 hours, and the heating rate is 1-5°C min -1 .

[0020] In order to achieve the above objectives, the third aspect of the present application provides an application of a catalyst according to any of the above embodiments in the photocatalytic oxidation of alkane raw materials to produce alcohol, wherein the alkane raw materials are selected from one or more combinations of methane, ethane, propane and shale gas.

[0021] In one or more embodiments, the application includes:

[0022] Ultrasonic dispersion of the catalyst in water to obtain a dispersion, and then transfer the dispersion into a reactor;

[0023] Inert gas is introduced into the reactor to purge to expel part of the air in the reactor, and then the alkane raw material is added;

[0024] The dispersion is stirred to allow the catalyst to fully adsorb the alkane raw material, and then a xenon lamp is used to irradiate the interior of the reactor for a photocatalytic reaction. After the reaction is completed, gaseous products and liquid products are collected.

[0025] In one or more embodiments, the concentration of the catalyst in the dispersion is 0.07 to 0.09 g / L.

[0026] Preferably, the concentration of the catalyst in the dispersion is 0.08 g / L.

[0027] In one or more embodiments, the pressure of oxygen inside the reactor is 2.3×10 -4 ~13.4×10 - 4 MPa.

[0028] In one or more embodiments, the alkane feedstock is methane, ethane or propane, and the pressure of the alkane feedstock is 0.1 to 0.9 MPa.

[0029] In one or more embodiments, the alkane raw material is shale gas, the pressure of methane in the shale gas is 0.3-0.7 MPa, the pressure of ethane is 0.1-0.3 MPa, and the pressure of propane is 0.1-0.3 MPa.

[0030] In one or more embodiments, the illumination intensity of the xenon lamp is 300-500 mW cm -2 The reaction temperature of the photocatalytic reaction is room temperature, and the reaction time is 1 to 2 hours.

[0031] Different from the prior art, the present invention has the following advantages:

[0032] The catalyst of the present application uses an in-situ calcination method to introduce Ni-O-Zn sites at the interface of nickel clusters and zinc oxide nanomesh, forming a strong metal-semiconductor interaction and inducing the formation of electron-rich nickel clusters and electron-deficient oxygen vacancies. These structural features can serve as aggregation sites for photogenerated holes and electrons, respectively, promoting the separation and migration of photogenerated carriers. The electron-rich nickel clusters can also serve as adsorption and activation sites for methane, ethane, and propane molecules, and synergistically with the electron-deficient oxygen vacancies to stabilize the methyl, ethyl, and isopropyl intermediates in the reaction process, significantly enhancing the photocatalytic activity.

[0033] The catalyst of this application has a wide range of substrate applicability and has achieved the simultaneous photooxidation of methane, ethane, and propane for the first time. It also shows excellent activity for the more complex photooxidation of shale gas. The yield of alcohol produced is at the forefront of the world in both the field of photocatalysis and the field of thermocatalysis.

[0034] The catalyst of the present application can catalyze the photooxidation of methane, ethane, propane, and shale gas to produce methanol, ethanol, and isopropanol under mild conditions of room temperature and low oxygen concentration, thereby reducing the degree of peroxidation in the reaction and thus increasing the selectivity of the corresponding alcohols. This is conducive to the promotion of the catalyst to industrial applications and helps to prepare high-value-added chemical products from non-petroleum raw materials at low cost.

[0035] The catalyst of the present application has excellent photocatalytic oxidation performance and stability and is reusable, providing a new solution for the photocatalytic oxidation of methane, ethane, propane and shale gas to produce the corresponding alcohols. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 This is a schematic flow chart of an embodiment of a method for preparing a catalyst for light-driven oxidation of beige gas to alcohols according to the present invention;

[0038] Figure 2 This is a schematic flow chart of an embodiment of the method for preparing alcohols by photooxidation of alkanes using a catalyst according to the present application;

[0039] Figure 3 This is a characterization analysis diagram of the catalyst of Example 1 of the present application, wherein: Figure 3 a is a high-angle annular dark-field scanning transmission electron microscope image of the catalyst of Example 1, Figure 3 b is a statistical diagram of nickel cluster size of the catalyst of Example 1, Figure 3 c is the element distribution diagram of the catalyst of Example 1, Figure 3 d is a high-resolution transmission electron microscope image of the catalyst of Example 1, Figure 3 e and 3f are X-ray diffraction patterns of the catalyst of Example 1;

[0040] Figure 4 is an X-ray photoelectron spectrum of the catalyst of Example 1 of the present application, wherein, Figure 4 a is the Ni 2p X-ray photoelectron spectrum of the catalyst of Example 1, Figure 4 b is the Zn2p X-ray photoelectron spectrum of the catalyst of Example 1;

[0041] Figure 5 This is a data chart of the product yields and isopropanol selectivity of the catalysts of Example 1 and Comparative Examples 1 to 9 in Effect Example 2 of the present application, wherein: Figure 5 a is the data of Example 1 and Comparative Examples 1 to 4, Figure 5 b is the data of Example 1 and Comparative Examples 5 to 6, Figure 5 c is the data of Example 1 and Comparative Examples 7 to 9;

[0042] Figure 6 This is a stability test chart of 22 cycles of photocatalytic propane oxidation to produce isopropyl alcohol using the catalyst of Example 1 in Effect Example 2 of the present application;

[0043] Figure 7 2 is a data graph of the yield of each product and isopropyl alcohol selectivity of the catalysts of Example 1, Comparative Example 1, and Comparative Examples 10 to 20 in Effect Example 2 of the present application;

[0044] Figure 8 This is a data chart of the product yields and isopropanol selectivity of the catalyst in Example 3 of the present application, wherein: Figure 8 a is the data of Application Example 1 and Application Comparative Examples 1 to 2, Figure 8 b is the data of application examples 1, 4 to 6, Figure 8 c is the data of Application Examples 1, 7 to 8;

[0045] Figure 9 This is a data chart of the yield of each product and the selectivity of methanol or ethanol in Example 9 to 10 of the effect example 4 of the present application, wherein: Figure 9 a is the data of Application Example 9, Figure 9 b is the data of Application Example 10;

[0046] Figure 10 This is a stability test chart of 22 cycles of photocatalytic methane oxidation to methanol by the catalyst of Example 1 in Effect Example 4 of the present application;

[0047] Figure 11This is a stability test chart of 22 cycles of photocatalytic ethane oxidation to ethanol using the catalyst of Example 1 in Effect Example 4 of the present application;

[0048] Figure 12 This is a data chart of the yields of the products of Example 11 to 13 in Example 4 of the present application;

[0049] Figure 13 This is a stability test chart of 22 cycles of photocatalytic shale gas oxidation to alcohol using the catalyst of Example 1 in Effect Example 4 of the present application. DETAILED DESCRIPTION

[0050] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0051] Currently, research on photochemical alkane conversion mainly focuses on single alkanes such as methane, ethane or propane. There have been no reports on the photooxidation of multiple alkanes or multi-component shale gas. As a result, existing technologies cannot directly convert shale gas into high-value-added products under mild conditions.

[0052] Given that the C-H bond enthalpies of ethane and propane are lower than those of methane, noble metal / metal oxide composites, traditionally used for CH photooxidation research, show potential applications in the conversion of multi-carbon alkanes. More importantly, strong metal-support interactions (SMSIs) can further enhance interfacial charge transfer, accelerate adsorbate conversion, and weaken the oxidation potential. However, the use of noble metals may limit their potential industrial applications. From an economic perspective, an ideal catalyst should be able to use non-noble metals as catalysts and use inexpensive oxidants (such as oxygen) to simultaneously trigger the CH oxidation of methane, ethane, propane, and even shale gas.

[0053] To address the above-mentioned issues, the applicant has developed a novel light-driven shale gas oxidation to alcohol catalyst. This catalyst does not use precious metals as raw materials and can achieve the simultaneous oxidation of methane, ethane, propane, and shale gas, thereby improving conversion efficiency. It can also effectively reduce the occurrence of overoxidation reactions, thereby increasing the selectivity of the target products methanol, ethanol, and isopropanol.

[0054] Specifically, the catalyst of the present application includes a carrier and nickel clusters supported on the carrier, wherein the carrier is a zinc oxide nanomesh.

[0055] In one embodiment, Ni—O—Zn linkages exist at the interface between the nickel clusters of the catalyst and the zinc oxide nanomesh of the support.

[0056] In one embodiment, the atomic percentage of nickel clusters in the catalyst may be 1.4 to 1.8 at %.

[0057] More preferably, the atomic percentage of nickel clusters in the catalyst may be 1.6 at %.

[0058] The catalyst provided herein features close contact between its components. By introducing Ni-O-Zn sites at the interface between nickel clusters and zinc oxide nanomesh, a strong metal-semiconductor interaction (SMSI) is formed, inducing the formation of electron-rich nickel clusters and electron-deficient oxygen vacancies. These structural features serve as aggregation sites for photogenerated holes and electrons, respectively, promoting the separation and migration of photogenerated carriers.

[0059] In addition, the electron-rich nickel clusters can also serve as adsorption and activation sites for methane, ethane, and propane molecules, and synergistically act with the electron-deficient oxygen vacancies to stabilize the methyl, ethyl, and isopropyl intermediates in the reaction process, significantly enhancing the photocatalytic activity.

[0060] In addition, the catalyst of the present application has a wider substrate applicability, can achieve simultaneous photooxidation of methane, ethane and propane, and still shows excellent activity for the more complex shale gas photooxidation; in particular, the photocatalytic reaction of the catalyst of the present application can be carried out at room temperature and low oxygen concentration, thereby effectively avoiding peroxidation reactions and improving the selectivity of the target product alcohol, which is conducive to its promotion to industrial applications.

[0061] This application also provides a method for preparing the above catalyst, please refer to Figure 1 , Figure 1 It is a flow chart of one embodiment of the method for preparing a catalyst for light-driven oxidation of beryllium gas to alcohols according to the present application.

[0062] like Figure 1 As shown, the preparation method comprises:

[0063] S100, dissolving zinc salt and nickel salt in water to obtain solution I.

[0064] In one embodiment, the zinc salt may be zinc acetate, and the nickel salt may be nickel acetate; in other embodiments, the zinc salt and the nickel salt may also be any optional soluble salts, and the effects of this embodiment can be achieved.

[0065] In one embodiment, the molar ratio of zinc ions to nickel ions in solution I is 10:(0.09-0.11).

[0066] More preferably, the molar ratio of zinc ions to nickel ions in solution I may be 10:0.1.

[0067] S200, dissolving urea in water to obtain solution II.

[0068] In one embodiment, the molar ratio of urea to nickel ions may be 35:(0.0875-0.1125).

[0069] More preferably, the molar ratio of urea to nickel ions may be 35:0.1.

[0070] S300, subjecting the mixed solution to a hydrothermal reaction, collecting the precipitate by filtration, and then washing and drying to obtain an intermediate product.

[0071] In one embodiment, the temperature of the hydrothermal reaction may be 100-120° C., and the time may be 10-14 hours.

[0072] More preferably, the temperature of the hydrothermal reaction may be 100° C., and the time may be 12 h.

[0073] S400, calcining the intermediate product at high temperature to obtain a catalyst.

[0074] In one embodiment, the high temperature calcination temperature can be 480-520°C, the time can be 10-14 hours, and the high temperature calcination can be carried out in a muffle furnace, and the heating rate of the muffle furnace can be 1-5°C min -1 .

[0075] More preferably, the high temperature calcination temperature can be 500 ° C, the time is 12 hours, and the high temperature calcination can be carried out in a muffle furnace, and the heating rate of the muffle furnace can be 5 ° C min -1 .

[0076] The catalyst components prepared by the traditional two-step calcination method are not in close contact with each other, and the interaction between the components is weak, resulting in a large interface resistance for the migration and separation of photogenerated carriers. The present application adopts an in-situ calcination method to introduce Ni-O-Zn sites at the interface of nickel clusters and zinc oxide nanomesh to form a strong metal-semiconductor interaction (SMSI), inducing the formation of electron-rich nickel clusters and electron-deficient oxygen vacancies. These structural features can serve as aggregation sites for photogenerated holes and electrons, respectively, to promote the separation and migration of photogenerated carriers. In addition, the electron-rich nickel clusters can also serve as adsorption and activation sites for methane, ethane and propane molecules, and the synergistic effect with electron-deficient oxygen vacancies stabilizes the methyl, ethyl and isopropyl intermediates in the reaction process, significantly enhancing the photocatalytic activity.

[0077] This application also provides a method for photooxidation of alkanes to alcohols using any of the above-mentioned catalysts. Figure 2 , Figure 2 It is a schematic flow chart of one embodiment of the method for preparing alcohols by photooxidation of alkanes using a catalyst according to the present application.

[0078] like Figure 2 As shown, the method includes:

[0079] S10, ultrasonically dispersing the catalyst in water to obtain a dispersion, and then transferring the dispersion into a reactor.

[0080] In one embodiment, the concentration of the catalyst in the dispersion may be 0.057 to 0.133 g / L.

[0081] More preferably, in one embodiment, the concentration of the catalyst in the dispersion may be 0.08 g / L.

[0082] In one embodiment, the volume of the dispersion may be 15.0 to 35.0 mL.

[0083] S20, introducing an inert gas into the reactor to purge and expel part of the air in the reactor, and then adding an alkane.

[0084] The catalyst of the present application is used under low oxygen concentration, and part of the air in the kettle can be removed by purging with inert gas, thereby controlling the residual oxygen concentration in the kettle.

[0085] In one embodiment, the oxygen concentration in the kettle can be 2.3×10 -4 ~13.4×10 -4 MPa.

[0086] More preferably, the oxygen pressure inside the reactor is 6.0×10 -4 ~9.0×10 -4 MPa.

[0087] The alkane may be selected from one or more combinations of methane, ethane, propane and shale gas.

[0088] In one embodiment, when the alkane is methane, ethane or propane, the pressure of the alkane may be 0.1 to 0.9 MPa.

[0089] In another embodiment, when the alkane is shale gas, the pressure of methane in the shale gas is 0.3-0.7 MPa, the pressure of ethane is 0.1-0.3 MPa, and the pressure of propane is 0.1-0.3 MPa.

[0090] S30, stirring the dispersion to allow the catalyst to fully absorb the alkane raw material, then using a xenon lamp to irradiate the interior of the reactor for a photocatalytic reaction, and collecting gaseous and liquid products after the reaction is completed.

[0091] In one embodiment, the illumination intensity of the xenon lamp is 300-500 mW cm -2 .

[0092] In one embodiment, the reaction temperature of the photocatalytic reaction may be room temperature, and the reaction time may be 1 to 2 hours.

[0093] The effects of the technical solution of this application are further elaborated in detail below with reference to specific embodiments.

[0094] Example 1:

[0095] A catalyst comprises a zinc oxide nanomesh carrier and nickel clusters loaded on the zinc oxide nanomesh carrier, wherein the atomic percentage of the nickel clusters in the catalyst is 1.6 at%.

[0096] The preparation process of the catalyst of this embodiment is as follows:

[0097] Step 1: Dissolve 10.0 mmol Zn(CH3COO)2·2H2O and 0.1 mmol Ni(CH3COO)2·4H2O in 10.0 mL water to prepare Solution I. Simultaneously, dissolve 35.0 mmol urea in 10.0 mL water to prepare Solution II.

[0098] Step 2: Solution I was continuously stirred at 600 rpm, while solution II was added dropwise to the solution and stirring was continued for 10 min. Subsequently, the mixed solution was transferred to a 40.0 mL hydrothermal kettle and reacted at 100 ° C for 12 h. After the hydrothermal kettle was naturally cooled to room temperature, the precipitate was washed four times with deionized water and dried in an 80 ° C oven for 5 h to obtain product A.

[0099] Step 3: Place the product A powder in a muffle furnace and heat at 5°C min -1 The temperature was raised to 500°C at a heating rate of 1000 ℃ and calcined at this temperature for 12 hours. After cooling to room temperature in the furnace, nickel cluster / zinc oxide nanomesh catalyst powder was obtained, which was recorded as Ni / ZnO NM.

[0100] Examples 2 to 3:

[0101] The preparation methods of the catalysts of Examples 2 to 3 are substantially the same as those of Example 1, except that:

[0102] The amounts of Ni(CH3COO)2·4H2O used in the catalysts of Examples 2 to 3 were 0.09 and 0.11 mmol, respectively. Correspondingly, the atomic percentages of nickel clusters in the catalysts were 1.4 at% and 1.8 at%, respectively.

[0103] Examples 4 to 5:

[0104] The preparation methods of the catalysts of Examples 4 to 5 are substantially the same as those of Example 1, except that:

[0105] The calcination temperatures of the catalysts of Examples 4 and 5 were 480°C and 520°C, respectively.

[0106] Examples 6 to 7:

[0107] The preparation methods of the catalysts of Examples 6 to 7 are substantially the same as those of Example 1, except that:

[0108] The calcination times of the catalysts of Examples 6 and 7 were 10 h and 14 h, respectively.

[0109] Comparative Examples 1 to 4:

[0110] The preparation methods of the catalysts of Comparative Examples 1 to 4 are substantially the same as those of Example 1, except that:

[0111] The amounts of Ni(CH3COO)2·4H2O in the catalysts of Comparative Examples 1 to 4 were 0.00, 0.05, 0.15, and 0.20 mmol, respectively. Correspondingly, the atomic percentages of nickel clusters in the catalysts were 0.0 at%, 0.8 at%, 2.4 at%, and 3.2 at%, respectively.

[0112] Comparative Examples 5 to 6:

[0113] The preparation methods of the catalysts of Comparative Examples 5 to 6 are substantially the same as those of Example 1, except that:

[0114] The calcination temperatures of the catalysts of Comparative Examples 5 to 6 were 400°C and 600°C, respectively.

[0115] Comparative Examples 7 to 9:

[0116] The preparation methods of the catalysts of Comparative Examples 7 to 9 are substantially the same as those of Example 1, except that:

[0117] The calcination times of the catalysts of Comparative Examples 7 to 9 are 4 h, 8 h, and 16 h, respectively.

[0118] Comparative Examples 10 to 11:

[0119] The preparation methods of the catalysts of Comparative Examples 10 to 11 are substantially the same as those of Example 1, except that:

[0120] Comparative Examples 10 to 11 respectively use the same molar amounts of In(CH3COO)3·6H2O and Ga(CH3COO)3 to replace Zn(CH3COO)2·2H2O in Example 1. The catalysts of Comparative Examples 1 and 2 are denoted as Ni / In2O3NM and Ni / Ga2O3NM, respectively.

[0121] Comparative Examples 12 to 20:

[0122] The preparation methods of the catalysts of Comparative Examples 12 to 20 are substantially the same as those of Example 1, except that:

[0123] Comparative Examples 12 to 20 respectively used the same molar amounts of silver salt, gold salt, platinum salt, palladium salt, chromium salt, manganese salt, iron salt, copper salt, and cobalt salt to replace Ni(CH3COO)2·4H2O in Example 1. The catalysts of Comparative Examples 3 to 11 were respectively designated as: Ag / ZnO NM, Au / ZnO NM, Pt / ZnO NM, Pd / ZnO NM, Cr / ZnONM, Mn / ZnO NM, Fe / ZnO NM, Cu / ZnO NM, and Co / ZnONM.

[0124] The preparation parameters of the catalysts in the above examples and comparative examples are shown in the table below:

[0125]

[0126]

[0127] Effect Example 1: Characterization Analysis

[0128] The catalyst of Example 1 was characterized and analyzed. Specifically, the morphology, elemental composition and phase structure of the catalyst of Example 1 were analyzed by high-angle annular dark field imaging-scanning transmission electron microscopy (HAADF-STEM), element distribution mapping (EDS-mapping), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction imaging (XRD). Figure 3 , Figure 3 This is a characterization analysis diagram of the catalyst of Example 1 of the present application, wherein: Figure 3 a is a high-angle annular dark-field scanning transmission electron microscope image of the catalyst of Example 1, Figure 3 b is a statistical diagram of nickel cluster size of the catalyst of Example 1, Figure 3 c is the element distribution diagram of the catalyst of Example 1, Figure 3 d is a high-resolution transmission electron microscope image of the catalyst of Example 1, Figure 3 3e and 3f are X-ray diffraction patterns of the catalyst of Example 1.

[0129] exist Figure 3 As can be seen in a, zinc oxide presents a nano-network structure, and clusters exist at the edge of the zinc oxide nano-network; Figure 3 In b, it can be seen that the size of the cluster is about 8.4 nm; Figure 3 The EDS-mapping of c clearly shows that these clusters are nickel clusters; Figure 3In the HRTEM image (d), the interplanar spacing of 0.22 nm and 0.26 nm corresponds to the {002} planes of the nickel clusters and the {002} planes of the zinc oxide nanomesh, respectively. These results together indicate that the nickel clusters have been successfully loaded on the zinc oxide nanomesh support.

[0130] In addition, Figure 3 e and Figure 3 The XRD pattern of Figure 1 shows that the catalyst of Example 1 has a close-packed hexagonal zinc oxide phase. No diffraction peaks for nickel clusters are observed, likely due to a low nickel cluster loading or high dispersion. Furthermore, the introduction of nickel clusters does not shift the zinc oxide diffraction peaks, indicating that the nickel clusters are only loaded at the edges of the zinc oxide nanomesh and do not enter the zinc oxide lattice.

[0131] Furthermore, the surface chemical structure characteristics of the catalyst of Example 1 were analyzed by X-ray photoelectron spectroscopy (XPS), and the results were as follows: Figure 4 , Figure 4 is an X-ray photoelectron spectrum of the catalyst of Example 1 of the present application, wherein, Figure 4 a is the Ni 2p X-ray photoelectron spectrum of the catalyst of Example 1, Figure 4 b is the Zn 2p X-ray photoelectron spectrum of the catalyst of Example 1.

[0132] like Figure 4 As shown in a, the Ni 2p XPS spectrum shows that the nickel element in the catalyst is Ni 0 and Ni δ+ The formation of coexistence. Among them, Ni 0 From nickel clusters, and Ni δ+ It comes from the Ni-O-Zn interface formed by nickel clusters and zinc oxide nanonets. 0 The peak shifts to lower binding energy, indicating that electrons are transferred from ZnO nanonetworks to Ni clusters.

[0133] like Figure 4 As shown in (b), the Zn 2p XPS spectrum shows that the zinc element mainly exists in the form of zinc oxide, and its XPS peak shifts toward high binding energy, further proving that electrons are transferred from the zinc oxide nanonet to the nickel clusters.

[0134] The above results once again prove that nickel clusters are successfully loaded on the zinc oxide nanomesh carrier and there is a strong interaction between the two.

[0135] Effect Example 2: Catalytic Performance Analysis

[0136] The performance of the above catalysts for photocatalytic propane oxidation to isopropyl alcohol was evaluated in a 100 mL top-illuminated autoclave. Example 1 was selected as a representative example and compared with the comparative examples. The specific experimental steps are as follows:

[0137] S1. Disperse 2.0 mg of the catalyst in 25.0 mL of water and sonicate for 10 min to form a uniform dispersion. The dispersion is then transferred to an autoclave.

[0138] S2. Before the reaction, the autoclave was purged with argon for 15 minutes to expel some of the air in the autoclave and reduce the oxygen concentration to reduce the degree of product overoxidation. The residual oxygen pressure was 7.5×10 -4 MPa, and then filled with 0.9MPa propane gas.

[0139] S3. After stirring for 10 min to allow the catalyst to adsorb propane gas to saturation, a 300W xenon lamp (light intensity: 400mW cm -2 ) Irradiate the high-pressure reactor from the top. After 1 hour of reaction, collect the gaseous and liquid products for detection.

[0140] The gaseous product content was detected by gas chromatography (Agilent) equipped with a hydrogen flame ionization detector (FID) and a thermal conductivity detector (TCD); the liquid product content was detected by nuclear magnetic resonance spectroscopy, and dimethyl sulfoxide (DMSO, 100 ppm) was used as the internal standard for quantification. The product yields and isopropanol selectivity data of the catalyst were obtained and sorted out. Figures 5 to 7 .

[0141] in, Figure 5 This is a data chart of the product yields and isopropanol selectivity of the catalysts of Example 1 and Comparative Examples 1 to 9 in Effect Example 2 of the present application, wherein: Figure 5 a is the data of Example 1 and Comparative Examples 1 to 4, Figure 5 b is the data of Example 1 and Comparative Examples 5 to 6, Figure 5 c is the data of Example 1 and Comparative Examples 7 to 9.

[0142] First, see Figure 5 a. We selected the data of Example 1 and Comparative Examples 1 to 4 for comparison to study the effect of the atomic percentage of nickel clusters on the catalyst performance. The results showed that the catalyst of Example 1 with a nickel cluster atomic percentage of 1.6 at% had the best catalytic performance, and its photocatalytic propane oxidation yield to isopropanol was 7.1 mmol h -1 g -1, the selectivity is 83.5%, which is much greater than that of Comparative Examples 1 to 4. Therefore, it can be seen that too much or too little atomic percentage of nickel clusters in the catalyst of the present application will affect the photocatalytic oxidation performance of the catalyst and the selectivity to the target product.

[0143] See also Figure 5 b. We selected the data of Example 1 and Comparative Examples 5 to 6 for comparison to study the effect of the calcination temperature of the catalyst on the catalyst performance. The results showed that the catalytic performance and target product selectivity of the catalyst of Example 1 with a calcination temperature of 500°C were much better than those of Comparative Examples 5 to 6, which indicates that a suitable calcination temperature is crucial to the catalytic performance and selectivity of the catalyst of the present application, and that too high or too low a calcination temperature will affect the performance of the catalyst of the present application.

[0144] See also Figure 5 c. We selected the data of Example 1 and Comparative Examples 7 to 9 for comparison to study the effect of the calcination time of the catalyst at 500°C on the catalytic performance. The results showed that the catalytic performance and target product selectivity of the catalyst of Example 1 with a calcination time of 12h were far superior to those of other comparative examples. When the calcination time was 4 or 8h, the product yield was too low and the isopropanol selectivity was low; when the calcination time reached 16h, the product yield was high but the isopropanol selectivity was too low; therefore, the appropriate calcination time is very critical to the catalytic performance of the catalyst of the present application.

[0145] In order to verify the stability of the catalyst of Example 1, we repeated the above photocatalytic reaction for 22 cycles using the catalyst of Example 1 and obtained Figure 6 . Figure 6 This is a stability test chart of 22 cycles of photocatalytic propane oxidation to produce isopropyl alcohol by the catalyst of Example 1 in Effect Example 2 of this application.

[0146] like Figure 6 As shown, during the 22 consecutive cycles, there was no significant fluctuation in the yield and selectivity of isopropanol, indicating that the catalyst in Example 1 maintained high stability throughout the entire photocatalytic cycle reaction and could be reused.

[0147] In order to study the effect of the carrier metal elements and cluster metal elements in the catalyst on the catalytic performance, we selected the data of Example 1, Comparative Example 1, and Comparative Examples 10 to 20 for comparison. Figure 7 , Figure 7 This is a data graph showing the yield of each product and isopropanol selectivity of the catalysts of Example 1, Comparative Example 1, and Comparative Examples 10 to 20 in Effect Example 2 of the present application.

[0148] Figure 7 The catalysts in each group are represented by element abbreviations, and the relevant descriptions of Example 1 and Comparative Examples 10 to 20 can be found above. In addition, ZnO NM corresponds to Comparative Example 1. Figure 7 As shown, when nickel clusters are replaced with other metal elements (such as silver, gold, platinum, palladium, chromium, manganese, iron, copper, and cobalt), the yield and selectivity of isopropyl alcohol are significantly reduced. When zinc oxide nanomesh is replaced with other transition metal oxide nanomesh (such as indium oxide and gallium oxide), the yield and selectivity of isopropyl alcohol are also significantly reduced. In particular, the catalyst of Comparative Example 1, which lacks nickel clusters, has a lower yield and selectivity of isopropyl alcohol than Example 1.

[0149] The above data show that the nickel and zinc elements in the catalyst of this application have a synergistic effect, significantly improving the catalyst's photocatalytic oxidation performance and target product selectivity. The reason may be that the interface between the nickel clusters and the zinc oxide nanomesh introduces Ni-O-Zn sites, forming a strong metal-semiconductor interaction (SMSI), inducing the formation of electron-rich nickel clusters and electron-deficient oxygen vacancies. These structural features can serve as aggregation sites for photogenerated holes and electrons, respectively, promoting the separation and migration of photogenerated carriers.

[0150] In the above Effect Example 2, we proved that the catalyst of Example 1 has the best catalytic performance and product selectivity. In order to study the influence of catalyst concentration and reaction gas concentration on the catalytic performance, we also conducted the following application experiments.

[0151] Application Example 1:

[0152] The performance of the catalyst of Example 1 in photocatalytic propane oxidation to produce isopropanol was evaluated in a top-illuminated autoclave with a total volume of 100 mL. The experimental parameters were exactly the same as those of Example 2.

[0153] Application Examples 2 to 3:

[0154] The performance of the catalyst of Example 1 in photocatalytic propane oxidation to produce isopropanol was evaluated in a top-illuminated autoclave with a total volume of 100 mL. The experimental parameters were essentially the same as those of Example 2, except that:

[0155] The volumes of the dispersions in Application Examples 2 to 3 were 23.0 mL and 27.0 mL, respectively, and the corresponding catalyst concentrations were 0.09 g / L and 0.11 g / L, respectively.

[0156] Application Examples 4 to 6:

[0157] The performance of the catalyst of Example 1 in photocatalytic propane oxidation to produce isopropanol was evaluated in a top-illuminated autoclave with a total volume of 100 mL. The experimental parameters were essentially the same as those of Example 2, except that:

[0158] The propane pressures in Application Examples 4 to 6 are 0.1, 0.3, and 0.6 MPa, respectively.

[0159] Application Examples 7 to 8:

[0160] The performance of the catalyst of Example 1 in photocatalytic propane oxidation to produce isopropanol was evaluated in a top-illuminated autoclave with a total volume of 100 mL. The experimental parameters were essentially the same as those of Example 2, except that:

[0161] The oxygen pressures in Application Examples 7 and 8 were 13.4×10 -4 MPa, 2.3×10 -4 MPa.

[0162] Application Comparative Examples 1 to 2:

[0163] The performance of the catalyst of Example 1 in photocatalytic propane oxidation to produce isopropanol was evaluated in a top-illuminated autoclave with a total volume of 100 mL. The experimental parameters were essentially the same as those of Example 2, except that:

[0164] The volumes of the dispersions in Comparative Application Examples 1 and 2 were 15.0 mL and 35.0 mL, respectively, and the corresponding catalyst concentrations were 0.13 g / L and 0.06 g / L, respectively.

[0165] The parameters of the above application examples and comparative examples are shown in the table below:

[0166]

[0167] Effect example 3:

[0168] The products of the above application examples and comparative examples were tested, and the product yield and isopropyl alcohol selectivity were calculated to obtain Figure 8 , Figure 8 This is a data chart of the product yields and isopropanol selectivity of the catalyst in Example 3 of the present application, wherein: Figure 8 a is the data of Application Example 1 and Application Comparative Examples 1 to 2, Figure 8 b is the data of application examples 1, 4 to 6, Figure 8 c is the data of Application Examples 1, 7 to 8.

[0169] First, see Figure 8 a. The catalyst in Example 1 has the best isopropanol activity and selectivity when the amount of water is 25.0 mL. When the concentration of the catalyst changes, its catalytic performance is greatly affected. Too high or too low a catalyst concentration will lead to a significant decrease in catalytic performance.

[0170] See also Figure 8b. When the propane pressure is 0.9 MPa, the catalyst has the best isopropanol activity and selectivity. When the propane pressure gradually increases, the yield of the catalyst in photocatalytic propane oxidation to alcohol gradually increases, and the isopropanol selectivity also gradually increases. However, when the propane pressure is in the range of 0.1 to 0.9 MPa, the catalyst of Example 1 can effectively catalyze the oxidation of propane to produce isopropanol.

[0171] See also Figure 8 c, oxygen pressure is 7.5×10 -4 MPa, it has the best isopropanol activity and selectivity. Too high or too low oxygen pressure will inhibit the performance of the catalyst in photocatalytic oxidation of propane to alcohol. However, when the oxygen pressure is 2.3×10 -4 ~13.4×10 -4 MPa, the catalysts of Example 1 can effectively catalyze the oxidation of propane to produce isopropanol. From the above data, it can be seen that the catalysts of the present application can be used under low oxygen concentrations, thereby helping to reduce overoxidation reactions and improve the selectivity of the target product.

[0172] In the above examples, we have demonstrated that the catalyst of the present application has excellent performance in photocatalytic propane oxidation to alcohol and excellent isopropanol selectivity. In order to further verify the wide substrate applicability of the catalyst of the present application, we also conducted the following application experiments.

[0173] Application Example 9:

[0174] The performance of the catalysts of Comparative Example 1 and Example 1 in photocatalytic oxidation of methane to produce methanol was evaluated in a top-illuminated autoclave with a total volume of 100 mL. The experimental parameters were substantially the same as those of Example 1, except that:

[0175] Application Example 9 uses 0.9 MPa methane to replace the propane in Application Example 1.

[0176] Application Example 10:

[0177] The performance of the catalysts of Comparative Example 1 and Example 1 in photocatalytic oxidation of ethane to ethanol was evaluated in a top-illuminated autoclave with a total volume of 100 mL. The experimental parameters were substantially the same as those of Example 1, except that:

[0178] In Application Example 10, 0.9 MPa ethane is used to replace the propane in Application Example 1.

[0179] Application Example 11:

[0180] The performance of the catalyst of Example 1 in photocatalytic oxidation of shale gas to produce the corresponding alcohol was evaluated in a top-illuminated autoclave with a total volume of 100 mL. The experimental parameters were basically the same as those of Application Example 1, except that:

[0181] Application Example 11 uses 0.9 MPa shale gas to replace the propane in Application Example 1, wherein the shale gas includes 0.3 MPa methane, 0.3 MPa ethane, and 0.3 MPa propane.

[0182] Application Example 12:

[0183] The performance of the catalyst of Example 1 in photocatalytic oxidation of shale gas to produce the corresponding alcohol was evaluated in a top-illuminated autoclave with a total volume of 100 mL. The experimental parameters were basically the same as those of Application Example 1, except that:

[0184] Application Example 12 uses 0.9 MPa shale gas to replace the propane in Application Example 1, wherein the shale gas includes 0.5 MPa methane, 0.2 MPa ethane, and 0.2 MPa propane.

[0185] Application Example 13:

[0186] The performance of the catalyst of Example 1 in photocatalytic oxidation of shale gas to produce the corresponding alcohol was evaluated in a top-illuminated autoclave with a total volume of 100 mL. The experimental parameters were basically the same as those of Application Example 1, except that:

[0187] Application Example 13 uses 0.9 MPa shale gas to replace the propane in Application Example 1, wherein the shale gas includes 0.7 MPa methane, 0.1 MPa ethane, and 0.1 MPa propane.

[0188] Please refer to the table below for the parameters of the above application examples 9 to 13.

[0189]

[0190]

[0191] Effect Example 4:

[0192] The products of the above application examples 9 to 10 were tested, and the product yield and methanol or ethanol selectivity were calculated to obtain Figure 9 , Figure 9 This is a data chart of the yield of each product and the selectivity of methanol or ethanol in Example 9 to 10 of the effect example 4 of the present application, wherein: Figure 9 a is the data of Application Example 9, Figure 9 b is the data of Application Example 10.

[0193] like Figure 9 As shown in Figure 2, under optimized conditions, the catalyst in Example 1 can also achieve photocatalytic oxidation of methane and ethane to produce methanol and ethanol, respectively. Correspondingly, the methanol yield is 2.2 mmol g -1 h-1 , the selectivity was 92.1% and the ethanol yield was 2.8 mmol g -1 h -1 , with a selectivity of 91.8%.

[0194] However, the catalyst of Comparative Example 1 has a poor ability to catalyze methane and ethane under the optimized conditions, which is much lower than that of Example 1.

[0195] In order to verify the stability of the performance of the catalyst of Example 1 in photocatalytic oxidation of methane and ethane, we repeated the photocatalytic experiments of Application Example 9 and Application Example 10 for 22 cycles respectively using the catalyst of Example 1, and obtained Figure 10 and Figure 11 , Figure 10 This is a stability test chart of 22 cycles of photocatalytic methane oxidation to methanol by the catalyst of Example 1 in Effect Example 4 of this application. Figure 11 This is a stability test chart of 22 cycles of photocatalytic ethane oxidation to produce ethanol using the catalyst of Example 1 in Effect Example 4 of the present application.

[0196] like Figure 10 and Figure 11 As shown, during the 22 consecutive cycles, the yields and selectivities of methanol and ethanol did not fluctuate significantly, indicating that the catalyst in Example 1 maintained high stability throughout the entire photocatalytic cycle reaction and could be reused.

[0197] Furthermore, the products of the above application examples 11 to 13 were tested and the product yields were calculated to obtain Figure 12 , Figure 12 This is a data chart of the yield of each product of Example 11 to 13 in Example 4 of the present application.

[0198] like Figure 12 As shown in FIG1 , the catalyst of Example 1 can simultaneously catalyze the oxidation of methane, ethane, and propane in shale gas to produce the corresponding alcohols. When the pressure ratio of methane:ethane:propane in the shale gas is 0.3 MPa:0.3 MPa:0.3 MPa, the catalyst of Example 1 has the most optimized activity for the photooxidation of shale gas to produce the corresponding alcohols, and the total yield of methanol, ethanol, and isopropanol is 2.9 mmol g -1 h -1 .

[0199] In order to verify the stability of the performance of the catalyst in Example 1 for photocatalytic shale gas oxidation, we repeated the photocatalytic experiment of Example 11 for 22 cycles and obtained Figure 13 , Figure 13 This is a stability test chart of 22 cycles of photocatalytic shale gas oxidation to alcohol using the catalyst of Example 1 in Effect Example 4 of the present application.

[0200] like Figure 13 As shown, during the 22 consecutive cycles, the yields of methanol, ethanol and isopropanol did not fluctuate significantly, indicating that the catalyst in Example 1 maintained high stability throughout the entire photocatalytic cycle reaction and could be reused.

[0201] It will be apparent to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above, and that the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present application is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0202] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A catalyst for light-driven shale gas oxidation to alcohol, characterized in that: The invention comprises a carrier and nickel clusters loaded on the carrier, wherein the carrier is a zinc oxide nanonet.

2. The catalyst according to claim 1, characterized in that Ni—O—Zn connecting bonds exist at the interface between the nickel cluster and the zinc oxide nanonet.

3. The catalyst according to claim 1, characterized in that The atomic percentage of the nickel clusters in the catalyst is 1.4 to 1.8 at %; Preferably, the atomic percentage of the nickel clusters in the catalyst is 1.6 at %.

4. A method for preparing the catalyst according to any one of claims 1 to 3, characterized in that: include: Dissolving zinc salt and nickel salt in water to obtain solution I; Dissolve urea in water to obtain solution II; The solution I is continuously stirred, and during the stirring process, the solution II is added dropwise to the solution I to obtain a mixed solution; performing a hydrothermal reaction on the mixed solution, collecting the precipitate by filtration, and then washing and drying to obtain an intermediate product; The intermediate product is calcined at high temperature to obtain the catalyst.

5. The preparation method according to claim 4, characterized in that The molar ratio of zinc ions to nickel ions in the solution I is 10:(0.09-0.11); and / or, The molar ratio of urea to nickel ions in the mixed solution is 35:(0.0875-0.1125); and / or, The zinc salt is zinc acetate, and the nickel salt is nickel acetate.

6. The preparation method according to claim 4, characterized in that The hydrothermal reaction temperature is 100-120° C. and the reaction time is 10-14 hours; and / or, The calcination temperature of the high temperature calcination is 480-520°C, the time is 10-14h, and the heating rate is 1-5°C min -1 .

7. Use of the catalyst according to any one of claims 1 to 3 or the catalyst prepared by the preparation method according to any one of claims 4 to 6 in the photocatalytic oxidation of alkane feedstock to alcohol, wherein the alkane feedstock is selected from one or more combinations of methane, ethane, propane and shale gas.

8. The use according to claim 7, characterized in that include: Ultrasonic dispersion of the catalyst in water to obtain a dispersion, and then transfer the dispersion into a reactor; Inert gas is introduced into the reactor to purge to expel part of the air in the reactor, and then the alkane raw material is added; The dispersion is stirred to allow the catalyst to fully adsorb the alkane raw material, and then a xenon lamp is used to irradiate the interior of the reactor for a photocatalytic reaction. After the reaction is completed, gaseous products and liquid products are collected.

9. The use according to claim 8, characterized in that The concentration of the catalyst in the dispersion is 0.07 to 0.09 g / L; Preferably, the concentration of the catalyst in the dispersion is 0.08 g / L.

10. The use according to claim 8, characterized in that The pressure of oxygen inside the reactor is 2.3×10 -4 ~13.4×10 -4 MPa.

11. The use according to claim 8, characterized in that The alkane raw material is methane, ethane or propane, and the pressure of the alkane raw material is 0.1-0.9 MPa; and / or, The alkane raw material is shale gas, the pressure of methane in the shale gas is 0.3-0.7 MPa, the pressure of ethane is 0.1-0.3 MPa, and the pressure of propane is 0.1-0.3 MPa.

12. The use according to claim 8, characterized in that The illumination intensity of the xenon lamp is 300-500 mW cm -2 The reaction temperature of the photocatalytic reaction is room temperature, and the reaction time is 1 to 2 hours.

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