Oxide nanoparticle synergistic carbon-coated NiZn composite catalyst as well as preparation method and application thereof

Abstract

The invention discloses an oxide nanoparticle synergistic carbon-coated NiZn composite catalyst as well as a preparation method and application thereof. According to the technical scheme, the preparation method comprises the following steps: 1, dissolving nickel salt, zinc salt, nanoscale TiO2 and C6H8O7. H2O in deionized water, and continuously and uniformly stirring to form a colloidal solution; 2, stirring the colloidal solution prepared in the step 1 at 60-100 DEG C for 8-12 hours, and then drying to obtain a light green precursor; and step 3, calcining the precursor prepared in the step 2 in a nitrogen atmosphere at 400-600 DEG C for 1-3 hours to obtain the oxide nanoparticle synergistic carbon-coated NiZn composite catalyst. The catalyst catalyzes coupling of low-carbon alcohol to synthesize higher alcohol, so that the problem of mass transfer blockage caused by deep dehydrogenation of small-molecular alcohol in the process of preparing higher alcohol through bioethanol conversion is solved, and the product yield is increased; belongs to the technical field of catalysts.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and specifically relates to an oxide nanoparticle-coordinated carbon-coated NiZn composite catalyst and a preparation method and application thereof. Background Art

[0002] Higher alcohols are the main basic raw materials for the synthesis of various fine chemical products such as surfactants and detergents. In addition, due to its high calorific value, good hydrophobicity, and non-corrosiveness to engine pipes, it is considered to be an excellent liquid mixed fuel. There are many methods for preparing higher alcohols, such as the Ziegler process, the Fischer-Tropsch synthesis process, and the Guerbet process. Among the many methods for synthesizing higher alcohols, the catalytic conversion of bioethanol or small molecule alcohols from biomass fermentation into higher alcohols is more preferred.

[0003] The ethanol Guerbet coupling reaction has three steps, namely dehydrogenation, aldol condensation and hydrogenation. Among them, hydrogen transfer needs to be carried out on the metal active site, and the aldol condensation reaction is related to the alkaline site. The metal mostly uses transition metals, and the alkaline site is a solid base catalyst such as sodium hydroxide homogeneous base or hydrotalcite. Metal Ni shows good activity in the dehydrogenation-hydrogenation reaction, and it is a non-precious metal, so nickel is used as the metal active site. However, studies have found that the metal activity of nickel is too strong. When the CH bond is broken, the CC bond will also be broken. The breaking of the carbon-carbon bond is not conducive to the coupling of alcohols, resulting in the production of by-products. Therefore, in order to weaken the metal activity of nickel, a second metal Zn is added. The other two metals are simultaneously loaded on hydrophilic oxide nanoparticles and hydrophobic low-dimensional carbon nanomaterials, which can enhance the oil-water two-phase mass transfer characteristics and increase the yield of higher alcohols.

[0004] CN 117820077 A discloses a method for preparing diols by catalytic conversion of xylose. The catalyst active components Ni and Zn are from the corresponding non-precious metal salt solutions, and Ti is selected from oxides. The catalyst is prepared by a coprecipitation method. The method uses xylose, a biomass hydrolyzate, as a raw material, deionized water as a solvent, H2 as a hydrogen source, and a closed reaction is carried out at 200-270°C for 1-5 hours at a stirring rate of 800rpm, and then cooled to room temperature to obtain diols; however, the method exposes more metal active sites, resulting in too strong metal activity, which leads to the breaking of the CC bond of ethanol, making it difficult to achieve CC coupling in the reaction, and inhibiting the growth of the carbon chain. Summary of the invention

[0005] The first object of the present invention is to provide a method for synthesizing an oxide nanoparticle-coordinated carbon-coated NiZn composite catalyst NiZn@C-TiO2, wherein nickel salt, zinc salt, TiO2 and carbon source C6H8O7·H2O are combined by an impregnation method to form a mixed solution, which is then in situ reduced under high temperature calcination to form an oxide nanoparticle-coordinated carbon-coated NiZn composite catalyst.

[0006] The second purpose of the present invention is to provide an oxide nanoparticle-coated carbon-coated NiZn composite catalyst NiZn@C-TiO2, which is beneficial to solving the problem of mass transfer obstruction caused by deep dehydrogenation of small molecule alcohols in the process of bioethanol conversion to prepare higher alcohols, and improving the product yield.

[0007] The third purpose of the present invention is to provide an oxide nanoparticle-coated carbon-coated NiZn composite catalyst NiZn@C-TiO2 for use in the reaction of coupling low-carbon alcohols to synthesize higher alcohols, effectively solving the problem of low catalytic efficiency due to deep dehydrogenation of small molecule alcohols in the preparation of higher alcohols.

[0008] A method for preparing oxide nanoparticles and carbon-coated NiZn composite catalyst comprises the following steps:

[0009] Step 1: dissolve nickel salt, zinc salt, nano-TiO2 and C6H8O7·H2O in deionized water and stir continuously to form a colloidal solution;

[0010] Step 2: Stir the colloidal solution prepared in step 1 at 60-100° C. for 8-12 hours, and then dry to obtain a light green precursor;

[0011] Step 3: calcining the precursor prepared in step 2 at 400° C. to 600° C. for 1 to 3 h in a nitrogen atmosphere to obtain an oxide nanoparticle-coated carbon-encapsulated NiZn composite catalyst.

[0012] The molar ratio of Ni in the nickel salt, Zn in the zinc salt, C in C6H8O7·H2O, and Ti in TiO2 is 20:0.5-3:20-60:20-60.

[0013] Furthermore, in the above-mentioned method for preparing the oxide nanoparticle-carbon-coated NiZn composite catalyst, the nickel salt is Ni(NO3)2·6H2O.

[0014] Furthermore, in the above-mentioned method for preparing the oxide nanoparticle-carbon-coated NiZn composite catalyst, the zinc salt is Zn(NO3)2·6H2O.

[0015] Furthermore, in the above-mentioned method for preparing a composite catalyst of oxide nanoparticles and carbon-coated NiZn, the nickel salt, TiO 2、The molar ratio of C6H8O7·H2O is 1:2:2; the molar ratio of the nickel salt to the zinc salt is 20:1.

[0016] Furthermore, in the above-mentioned method for preparing the oxide nanoparticle-coated carbon-encapsulated NiZn composite catalyst, the stirring temperature in step 2 is 80° C. and the stirring time is 10 h.

[0017] Furthermore, in the above-mentioned method for preparing the oxide nanoparticle-carbon-coated NiZn composite catalyst, the calcination temperature in step 3 is 500° C. and the calcination time is 2 h.

[0018] The second technical solution of the present invention is to provide an oxide nanoparticle-coated carbon-coated NiZn composite catalyst, which is a NiZn@C-TiO2 catalyst prepared by the preparation method described in the first technical solution.

[0019] The third technical solution of the present invention is that the above-mentioned oxide nanoparticles cooperate with the carbon-coated NiZn composite catalyst to catalyze the coupling of low-carbon alcohols to synthesize higher alcohols.

[0020] Another technical solution of the present invention is a method for synthesizing higher alcohols by coupling low-carbon alcohols, which comprises the following steps in sequence:

[0021] 1) reducing the oxide nanoparticles and carbon-coated NiZn composite catalyst NiZn@C-TiO2 at 400-600°C for 1-3h in a N2 atmosphere;

[0022] 2) Then, in a stainless steel high-pressure slurry bed reactor, NaOH is added to catalyze ethanol CC coupling to synthesize higher alcohols, the reaction temperature is 150-220° C., the initial pressure is 0.1 MPa, the reaction time is 6-18 h, after the reaction is completed, the gas is collected and detected and analyzed by an Agilent gas chromatograph, and the liquid product is centrifuged and then detected and analyzed by gas chromatography.

[0023] Among them: the mass ratio of catalyst NiZn@C-TiO2:NaOH:ethanol:water is 0.3:0.8:5:5.

[0024] Compared with the prior art, the technical solution provided by the present invention has the following technical advantages:

[0025] 1. The technical solution provided by the present invention combines oxide nanoparticles TiO2 with carbon source C6H8O7·H2O, and fuses the precursor of active metal Ni Ni(NO3)2·6H2O and the precursor of metal Zn Zn(NO3)2·6H2O to form a colloidal emulsion, and then obtains oxide nanoparticles and carbon-coated NiZn composite catalysts through the in-situ reduction effect produced by high-temperature calcination and decomposition of C6H8O7·H2O, which is beneficial to solve the problem of mass transfer obstruction caused by deep dehydrogenation of small molecule alcohols in the process of converting bioethanol to prepare higher alcohols, and improves the product yield; it is also beneficial to solve the problem of low catalytic efficiency caused by two-phase separation in the reaction process of synthesizing high-carbon alcohols from low-carbon alcohols.

[0026] 2. The catalytic active centers of the carbon-coated catalyst provided by the present invention are highly dispersed and uniform, so that the catalyst has extremely high catalytic activity and selectivity. The coating effect of the carbon material can protect the metal atoms from the influence of the external environment and improve the stability and durability of the catalyst. In addition, the oxide nanoparticles cooperate with the carbon-coated catalyst to have amphiphilicity. During the reaction process, as the carbon chain grows, the phenomenon of water-oil separation will gradually appear. Generally, the catalyst will exist alone in the oil phase or the water phase, which is not conducive to the mass transfer of the reaction. The presence of the amphiphilic catalyst can strengthen the mass transfer between the two phases and improve the yield of high-carbon alcohols.

[0027] 3. The technical solution preparation method provided by the present invention adopts an impregnation method, the raw materials are widely available, simple and easy to obtain, do not contain precious metals, are inexpensive, and are economical and effective; the preparation process is simple, the operation is convenient, and it is conducive to industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the XRD pattern of the NiZn@C-TiO2 catalyst prepared in Example 1.

[0029] Figure 2 This is the TEM image of the NiZn@C-TiO2 catalyst prepared in Example 3.

[0030] Figure 3 The chromatogram of the liquid product. DETAILED DESCRIPTION

[0031] In order to make the purpose and advantages of the invention more obvious and easy to understand, the technical solutions in the embodiments of the invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the invention. Based on the embodiments of the invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the invention.

[0032] Example 1

[0033] (1) Preparation of Zn-doped NiZn@C-TiO2 catalyst.

[0034] 20mmol nickel nitrate hexahydrate, 1mmol zinc nitrate hexahydrate, 40mmol C6H8O7·H2O and 40mmol TiO2 were simultaneously added into 50ml deionized water and stirred to form a colloidal solution; the obtained colloidal solution was stirred at 80°C for 10h, placed in an oven at 80°C for 10h to obtain NiZn@C-TiO2 powder, and the NiZn@C-TiO2 powder was calcined and reduced at 500°C for 2h in a N2 atmosphere to obtain a highly dispersed Zn-doped NiZn@C-TiO2 catalyst.

[0035] Example 2

[0036] (1) Preparation of Zn-doped NiZn@C-TiO2 catalyst.

[0037] The difference between this embodiment and embodiment 1 is that in this embodiment, 20 mmol of nickel nitrate hexahydrate, 1 mmol of zinc nitrate hexahydrate, 20 mmol of C6H8O7·H2O and 40 mmol of TiO2 are used, and other reaction conditions and parameters are the same as those in embodiment 1.

[0038] Example 3

[0039] (1) Preparation of Zn-doped NiZn@C-TiO2 catalyst.

[0040] The difference between this embodiment and embodiment 1 is that in this embodiment, 20 mmol of nickel nitrate hexahydrate, 1 mmol of zinc nitrate hexahydrate, 60 mmol of C6H8O7·H2O and 40 mmol of TiO2 are used, and other reaction conditions and parameters are the same as those in embodiment 1.

[0041] Example 4

[0042] The difference between this embodiment and embodiment 1 is that in this embodiment, 20 mmol of nickel nitrate hexahydrate, 1 mmol of zinc nitrate hexahydrate, 40 mmol of C6H8O7·H2O and 20 mmol of TiO2 are used, and other reaction conditions and parameters are the same as those in embodiment 1.

[0043] Example 5

[0044] The difference between this embodiment and embodiment 1 is that in this embodiment, 20 mmol of nickel nitrate hexahydrate, 1 mmol of zinc nitrate hexahydrate, 40 mmol of C6H8O7·H2O and 60 mmol of TiO2 are used, and other reaction conditions and parameters are the same as those in embodiment 1.

[0045] Example 6

[0046] The difference between this embodiment and embodiment 1 is that in this embodiment, 20 mmol of nickel nitrate hexahydrate, 0.5 mmol of zinc nitrate hexahydrate, 40 mmol of C6H8O7·H2O and 40 mmol of TiO2 are used, and other reaction conditions and parameters are the same as those in embodiment 1.

[0047] Example 7

[0048] The difference between this embodiment and embodiment 1 is that in this embodiment, 20 mmol of nickel nitrate hexahydrate, 2 mmol of zinc nitrate hexahydrate, 40 mmol of C6H8O7·H2O and 40 mmol of TiO2 are used, and other reaction conditions and parameters are the same as those in embodiment 1.

[0049] Example 8

[0050] The difference between this embodiment and embodiment 1 is that in this embodiment, 20 mmol of nickel nitrate hexahydrate, 3 mmol of zinc nitrate hexahydrate, 40 mmol of C6H8O7·H2O and 40 mmol of TiO2 are used, and other reaction conditions and parameters are the same as those in embodiment 1.

[0051] Example 9

[0052] The difference between this embodiment and embodiment 1 is that in this embodiment, NiZn@C-TiO2 powder is calcined and reduced at 400°C in a N2 atmosphere for 2 hours.

[0053] Example 10

[0054] The difference between this embodiment and embodiment 1 is that in this embodiment, NiZn@C-TiO2 powder is calcined and reduced at 600°C in a N2 atmosphere for 2h.

[0055] Embodiment 11

[0056] The difference between this embodiment and embodiment 1 is that in this embodiment, NiZn@C-TiO2 powder is calcined and reduced at 500°C for 3 hours in a N2 atmosphere to obtain a highly dispersed Zn-doped NiZn@C-TiO2 catalyst.

[0057] In order to verify the catalyst provided by the present application, the applicant conducted XRD detection on the NiZn@C-TiO2 catalyst and Ni@C catalyst prepared in Example 1. The chromatograms thereof are shown in Figure 1 ,pass Figure 1 It can be seen that the XRD pattern of the NiZn@C-TiO2 catalyst has obvious diffraction peaks of TiO2 and nickel metal, among which the diffraction peaks at 44.5°, 51.8°, and 76.4° correspond to the Ni(111) crystal plane, Ni(200) crystal plane, and Ni(220) crystal plane of nickel metal, respectively. Due to the low doping amount of metal Zn, the diffraction peak of Zn could not be observed.

[0058] The NiZn@C-TiO2 catalyst prepared in Example 3 was subjected to TEM analysis. Figure 2 ,pass Figure 2 It can be seen that the carbon-coated metal particles are distributed on the TiO2 carrier to form oxide nanoparticles and carbon-coated NiZn composite catalysts.

[0059] Application Example 1

[0060] The highly dispersed Zn-doped NiZn@C-TiO2 catalyst prepared in Example 1 was reacted with a homogeneous base in a 70ml stainless steel high-pressure slurry bed reactor to catalyze the carbon-carbon coupling of ethanol to synthesize higher alcohols, wherein 0.3g of the NiZn@C-TiO2 catalyst prepared in Example 1, 0.8g of sodium hydroxide, 5g of ethanol, and 5g of water were reacted at a reaction temperature of 190°C, an initial pressure of 0.1MPa, and a reaction speed of 1000rpm. After the reaction, the gas and liquid products were collected until the reactor was cooled to room temperature, and the products were centrifuged to obtain a liquid phase and a solid phase, wherein the liquid phase product was centrifuged and allowed to stand for stratification to obtain an aqueous phase and an organic phase, and the main product of the organic phase was a higher alcohol, and its ethanol conversion rate, organic phase product yield, and C4+ higher alcohol carbon yield are shown in Table 1. The chromatogram of the liquid phase product is shown in Table 1. Figure 3 As shown, methanol is the solvent and C5-OH is the internal standard n-pentanol. It can be seen from the figure that C4+ high-carbon alcohols exist in the product, and the carbon number of the high-carbon alcohol can reach up to C18.

[0061] Application Example 2

[0062] The reaction conditions and parameters of this application example are consistent with those of Example 1, except that the catalyst provided in Example 2 is used. The ethanol conversion rate, organic phase product yield, and C4+ higher alcohol carbon yield are shown in Table 1.

[0063] Application Example 3

[0064] The reaction conditions and parameters of this application example are consistent with those of Example 1, except that the catalyst provided in Example 3 is used. The ethanol conversion rate, organic phase product yield, and C4+ higher alcohol carbon yield are shown in Table 1.

[0065] Application Example 4

[0066] The reaction conditions and parameters of this application example are consistent with those of Example 1, except that the catalyst provided in Example 4 is used. The ethanol conversion rate, organic phase product yield, and C4+ higher alcohol carbon yield are shown in Table 1.

[0067] Application Example 5

[0068] The reaction conditions and parameters of this application example are consistent with those of Example 1, except that the catalyst provided in Example 5 is used. The ethanol conversion rate, organic phase product yield, and C4+ higher alcohol carbon yield are shown in Table 1.

[0069] Application Example 6

[0070] The reaction conditions and parameters of this application example are consistent with those of Example 1, except that the catalyst provided in Example 6 is used. The ethanol conversion rate, organic phase product yield, and C4+ higher alcohol carbon yield are shown in Table 1.

[0071] Application Example 7

[0072] The reaction conditions and parameters of this application example are consistent with those of Example 1, except that the catalyst provided in Example 7 is used. The ethanol conversion rate, organic phase product yield, and C4+ higher alcohol carbon yield are shown in Table 1.

[0073] Application Example 8

[0074] The reaction conditions and parameters of this application example are consistent with those of Example 1, except that the catalyst provided in Example 8 is used. The ethanol conversion rate, organic phase product yield, and C4+ higher alcohol carbon yield are shown in Table 1.

[0075] Application Example 9

[0076] The reaction conditions and parameters of this application example are consistent with those of Example 1, except that the catalyst provided in Example 9 is used. The ethanol conversion rate, organic phase product yield, and C4+ higher alcohol carbon yield are shown in Table 1.

[0077] Application Example 10

[0078] The reaction conditions and parameters of this application example are consistent with those of Example 1, except that the catalyst provided in Example 10 is used. The ethanol conversion rate, organic phase product yield, and C4+ higher alcohol carbon yield are shown in Table 1.

[0079] Application Example 11

[0080] The reaction conditions and parameters of this application example are consistent with those of Example 1, except that the catalyst provided in Example 11 is used. The ethanol conversion rate, organic phase product yield, and C4+ higher alcohol carbon yield are shown in Table 1.

[0081] Comparative Example 1

[0082] (1) Preparation of Ni@C-TiO2 catalyst.

[0083] 20mmol nickel nitrate hexahydrate, 40mmol C6H8O7·H2O and 40mmol TiO2 are simultaneously added into 50ml deionized water and stirred to form a colloidal solution; the obtained colloidal solution is stirred at 80°C; after stirring for 10h, it is placed in an 80°C oven and dried to obtain Ni@C-TiO2 powder; the Ni@C-TiO2 powder is calcined and reduced at 500°C in a N2 atmosphere for 2h to obtain a Ni@C-TiO2 catalyst.

[0084] Comparative Example 2

[0085] (1) Preparation of Ni@C catalyst.

[0086] 20mmol nickel nitrate hexahydrate and 40mmol C6H8O7·H2O are simultaneously added into deionized water and stirred to form a colloidal solution; the obtained colloidal solution is stirred at 80°C; after stirring for 10 hours, it is placed in an 80°C oven for drying to obtain Ni@C powder, and the Ni@C powder is calcined and reduced at 500°C for 2 hours in a N2 atmosphere to obtain a highly dispersed Ni@C catalyst.

[0087] Comparative application example 1

[0088] The reaction conditions and parameters of this comparative application example are consistent with those of Example 1, except that the catalyst provided in Comparative Example 1 is used.

[0089] Comparative Application Example 2

[0090] The reaction conditions and parameters of this comparative application example are consistent with those of Example 1, except that the catalyst provided in Comparative Example 2 is used.

[0091] The gas products and liquid products of Example 1-11 and Comparative Example 1-2 were respectively detected and analyzed by gas chromatograph to obtain ethanol conversion rate, organic phase carbon yield, and C4+ alcohol selectivity. The results of Example 1-11 and Comparative Example 1-2 are shown in Table 1.

[0092] Table 1

[0093] Ethanol conversion (C-mol%) Organic phase product yield (C-mol%) C4+ higher alcohol carbon yield (C-mol%) Application Example 1 81.1 53.1 80.6 Application Example 2 69.4 42.6 69.2 Application Example 3 68.7 34.4 68.3 Application Example 4 66.0 40.5 66.3 Application Example 5 73.7 46.9 73.8 Application Example 6 79.7 53.3 79.6 Application Example 7 80.5 52.2 80.3 Application Example 8 72.6 48.5 72.5 Application Example 9 69.2 45.1 69.1 Application Example 10 78.2 51.0 77.9 Application Example 11 65.9 39.2 65.5 Comparative application example 1 68.5 40.2 68.1 Comparative Application Example 2 57.5 44.1 57.2

[0094] As can be seen from Table 1 above, the nickel-based catalysts prepared by different processes in Application Examples 1 to 11 and Comparative Application Examples 1 to 2 can all be used to catalyze the carbon-carbon coupling of ethanol to prepare higher alcohols, among which the catalyst prepared in Example 1 has the best catalytic performance, and the ethanol conversion rate, organic phase product yield, and C4+ higher alcohol yield in the liquid phase all reach a relatively high level.

Claims

1. A method for preparing oxide nanoparticles and carbon-coated NiZn composite catalyst, characterized in that: The following steps are involved: Step 1: dissolve nickel salt, zinc salt, nano-TiO2 and C6H8O7·H2O in deionized water and stir continuously to form a colloidal solution; Step 2: Stir the colloidal solution prepared in step 1 at 60-100° C. for 8-12 hours, and then dry to obtain a light green precursor; Step 3: calcining the precursor prepared in step 2 at 400° C. to 600° C. for 1 to 3 h in a nitrogen atmosphere to obtain an oxide nanoparticle-coated carbon-encapsulated NiZn composite catalyst. The molar ratio of Ni in the nickel salt, Zn in the zinc salt, C in C6H8O7·H2O, and Ti in TiO2 is 20:0.5-3:20-60:20-60.

2. The method for preparing a composite catalyst of oxide nanoparticles and carbon-coated NiZn according to claim 1, characterized in that: The nickel salt is Ni(NO3)2·6H2O.

3. The method for preparing a composite catalyst of oxide nanoparticles and carbon-coated NiZn according to claim 1, characterized in that: The zinc salt is Zn(NO3)2·6H2O.

4. The method for preparing a composite catalyst of oxide nanoparticles and carbon-coated NiZn according to claim 1, characterized in that: The nickel salt, TiO 2、 The molar ratio of C6H8O7·H2O is 1:2:2; the molar ratio of the nickel salt to the zinc salt is 20:

1.

5. The method for preparing a composite catalyst of oxide nanoparticles and carbon-coated NiZn according to claim 1, characterized in that: The stirring temperature in step 2 is 80° C. and the stirring time is 10 h.

6. The method for preparing a composite catalyst of oxide nanoparticles and carbon-coated NiZn according to claim 1, characterized in that: The calcination temperature in step 3 is 500° C. and the calcination time is 2 h.

7. An oxide nanoparticle-coated carbon-coated NiZn composite catalyst, characterized in that: The NiZn@C-TiO2 catalyst is prepared by the preparation method described in any one of claims 1-6.

8. The oxide nanoparticles according to claim 7 cooperate with the carbon-coated NiZn composite catalyst to catalyze the coupling of low-carbon alcohols to synthesize higher alcohols.

9. A method for synthesizing higher alcohols by coupling low-carbon alcohols, characterized in that: The steps are as follows: 1) reducing the oxide nanoparticles and carbon-coated NiZn composite catalyst NiZn@C-TiO2 according to claim 7 at 400-600° C. for 1-3 h in a N2 atmosphere; 2) Then, in a stainless steel high-pressure slurry bed reactor, NaOH is added to catalyze ethanol CC coupling to synthesize higher alcohols, the reaction temperature is 150-220° C., the initial pressure is 0.1 MPa, the reaction time is 6-18 hours, after the reaction is completed, the gas is collected and then detected and analyzed by gas chromatography, and the liquid product is centrifuged and then detected and analyzed by gas chromatography; Among them: Catalyst NiZn@C-TiO 2、 The mass ratio of NaOH, ethanol and water is 0.3:0.8:5:5.

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