High-dispersity copper-based composite catalyst for hydrogen production through methanol steam reforming and simple preparation method of high-dispersity copper-based composite catalyst

Abstract

The invention provides a high-dispersity copper-based composite catalyst for hydrogen production through methanol steam reforming and a simple preparation method of the high-dispersity copper-based composite catalyst, and relates to the technical field of catalysts. According to the preparation method provided by the invention, fatty acid, nitrate and melamine are mixed, ground and calcined in a high-temperature inert atmosphere, so that the fatty acid is carbonized to generate amorphous carbon, the nitrate is decomposed into metal oxide nanoparticles, and the metal oxide nanoparticles are interwoven and coated with g-C3N4 to prevent particle aggregation; the porous CuO-ZnO-Al2O3 composite catalyst has the advantages that the adsorption and diffusion capabilities of reactants are obviously improved, the methanol conversion rate reaches 95% or above (250 DEG C), the H2 selectivity exceeds 75%, and the efficient and low-cost simple preparation of the catalyst for hydrogen production by methanol steam reforming is realized.

Description

Technical Field

[0001] This application relates to the field of catalyst technology, and more specifically, to a highly dispersed copper-based composite catalyst for methanol steam reforming to produce hydrogen and a simple preparation method thereof. Background Technology

[0002] Today, finding clean and efficient energy alternatives has become a common pursuit of the scientific and industrial communities. Hydrogen, as a pollution-free, high-calorific-value energy carrier, is considered a key component of the future energy system, especially showing broad application prospects in the field of fuel cells.

[0003] Methanol steam reforming (MSR) technology has become a research hotspot in the field of hydrogen production due to its advantages such as the high hydrogen-to-carbon ratio of methanol, low energy density, and mild reaction conditions. The core of MSR technology lies in the development of highly efficient catalysts, which need to possess high activity, high selectivity, and high stability to meet the requirements of large-scale industrial applications.

[0004] However, the preparation of existing methanol steam reforming catalysts faces a contradiction between performance and process. Traditional methods, such as direct calcination, are simple but difficult to obtain high-performance, stable materials; while advanced nanosynthesis methods can prepare high-performance catalysts, they are often difficult to scale up industrially due to complex processes and high costs.

[0005] Therefore, developing a preparation method that can ensure high catalyst performance, is simple, controllable, low-cost, and easy to scale up is key to the development of MSR technology. Summary of the Invention

[0006] The purpose of this application is to provide a highly dispersed copper-based composite catalyst for methanol steam reforming to produce hydrogen and its simple preparation method. The catalyst is prepared by a simple solid-phase method with Al2O3 support supporting active components CuO and ZnO. The catalyst has excellent catalytic reforming performance and is suitable for methanol steam reforming to produce hydrogen.

[0007] This application provides a simplified method for preparing a highly dispersed copper-based composite catalyst for methanol steam reforming to produce hydrogen, comprising the following steps:

[0008] S1. Place measured amounts of Cu(NO3)2·3H2O, Zn(NO3)2·6H2O, Al(NO3)3·9H2O, melamine, and vegetable oil in a mortar and grind them evenly to form a mixture.

[0009] S2. Transfer the mixture obtained in step S1 into a ceramic boat, place it in a tube furnace, and calcine it under an inert atmosphere. After calcination, allow it to cool naturally to room temperature to obtain precursor powder.

[0010] S3. Place the precursor powder obtained in step S2 in a muffle furnace and calcine it in an air atmosphere. After calcination, allow it to cool naturally to room temperature to obtain a highly dispersed copper-based composite catalyst for methanol steam reforming to produce hydrogen.

[0011] Furthermore, in step S1, the amount of melamine added is 3g, and the amount of fatty acid added is 6g; the fatty acid is selected from one or a mixture of two of soybean oil, corn oil, and rapeseed oil.

[0012] Furthermore, in step S2, the calcination conditions are: heating at 2℃ / min to 600℃ and maintaining for 2 h under a N2 atmosphere.

[0013] Furthermore, in step S3, the calcination conditions are: heating to 600°C at a rate of 2°C / min under air atmosphere and maintaining the temperature for 6 hours.

[0014] Further, in step S3, the composite catalyst is composed of an active component and a support, wherein the active component is CuO-ZnO and the support is Al2O3, wherein the mass percentage of CuO:ZnO:Al2O3 is 44.78~65.00:25.17~45.09:9.83~10.13.

[0015] Based on the same inventive concept, this application also provides a highly dispersed copper-based composite catalyst for methanol steam reforming to produce hydrogen, prepared using the above-described preparation method.

[0016] The beneficial effects of this invention are:

[0017] The preparation method provided by this invention involves thoroughly grinding and mixing viscous fatty acids, nitrates, and melamine to form a uniform mixture. After high-temperature calcination, a composite catalyst with a large specific surface area and excellent dispersibility can be obtained. During the calcination process in an inert atmosphere, the fatty acids are carbonized at high temperature to generate amorphous carbon, while the nitrates are decomposed and reduced to metal and its oxide nanoparticles. Simultaneously, the amorphous carbon and g-C3N4 generated from the decomposition of melamine intertwine to form an effective coating on the metal and its oxide particles, preventing agglomeration and sintering at high temperatures and ensuring the stable dispersion of the catalyst precursor. Subsequently, calcination in an air atmosphere removes the amorphous carbon and g-C3N4, leaving a rich porous structure. At the same time, the metal and its oxide particles are completely oxidized to composite oxides such as CuO, ZnO, and Al2O3. This porous structure significantly promotes the adsorption and diffusion of reactants on the catalyst surface, thereby effectively improving the hydrogen production efficiency of the methanol steam reforming hydrogen production reaction. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The XRD patterns are of the catalysts prepared in Examples 1-6 of this invention.

[0020] Figure 2 The activity test graphs are for the catalysts prepared in Examples 1-6 and Comparative Examples 1-2 of the present invention.

[0021] Figure 3 The above are H2 selectivity test graphs of the catalysts prepared in Examples 1-6 and Comparative Examples 1-2 of the present invention;

[0022] Figure 4 These are CO selectivity test graphs for the catalysts prepared in Examples 1-6 and Comparative Examples 1-2 of the present invention;

[0023] Figure 5 This is a TEM image of the catalyst prepared in Representative Example 1 of the present invention;

[0024] Figure 6 The figures show the nitrogen adsorption-desorption curves and pore size distribution of the catalysts prepared in Examples 1-6 of this invention. Detailed Implementation

[0025] To facilitate understanding of the present invention, it will be described more fully below through embodiments, and preferred embodiments are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Any other implementation schemes obtained by modifying or equivalently substituting the technical solutions of the present invention without inventive step are all within the protection scope of the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0027] The numerical values ​​disclosed in the embodiments of this invention are approximate values, not definitive values. Where error or experimental conditions permit, all values ​​within the error range may be included, and the specific numerical values ​​disclosed in the embodiments of this invention are not limited to those specified.

[0028] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0029] In the following examples, the Cu source is copper nitrate, the Zn source is zinc nitrate, and the Al source is aluminum nitrate.

[0030] In the following examples and comparative examples, a fixed-bed reactor was used to test the catalyst performance, and the gas phase products were analyzed using a GC2060 gas chromatograph from Shanghai Minrui Instruments Co., Ltd. to obtain the conversion rate and selectivity.

[0031] The following is a specific example:

[0032] Example 1

[0033] This embodiment provides a method for preparing a highly dispersed copper-based composite catalyst for methanol steam reforming to produce hydrogen, comprising the following steps:

[0034] S1: Place 1.635 g Cu(NO3)2·3H2O, 0.757 g Zn(NO3)2·6H2O, 0.599 g Al(NO3)3·9H2O, 3 g melamine and 6 g soybean oil in an agate mortar and grind them evenly.

[0035] S2: Transfer the mixture obtained in step S1 into a ceramic boat, place the ceramic boat in a tube furnace under an inert atmosphere and heat it to 600℃ at a heating rate of 2℃ / min for 2 hours for pyrolysis and calcination. After calcination, allow it to cool naturally to room temperature to obtain precursor powder.

[0036] S3: Place the precursor powder obtained in step S2 in a muffle furnace and calcine it to 600℃ for 6 h at a heating rate of 2℃ / min under air atmosphere. After calcination, allow it to cool naturally to room temperature to obtain the methanol steam reforming hydrogen production catalyst.

[0037] The methanol steam reforming hydrogen production catalyst prepared in this embodiment is labeled as catalyst 1. The mass percentage (wt%) of CuO:ZnO:Al2O3 in this catalyst is 65.00:25.17:9.83.

[0038] Example 2

[0039] This embodiment provides a method for preparing a highly dispersed copper-based composite catalyst for methanol steam reforming to produce hydrogen. The difference between this method and Example 1 is that in step S1, 1.358 g Cu(NO3)2·3H2O, 1.043 g Zn(NO3)2·6H2O, 0.599 g Al(NO3)3·9H2O, 3 g melamine and 6 g soybean oil are ground evenly in an agate mortar.

[0040] The copper-based composite catalyst for methanol steam reforming to produce hydrogen prepared in this embodiment is labeled as catalyst 2. The mass percentage (wt%) of CuO:ZnO:Al2O3 in this catalyst is 54.81:35.20:9.99.

[0041] Example 3

[0042] This embodiment provides a method for preparing a highly dispersed copper-based composite catalyst for methanol steam reforming to produce hydrogen. The difference between this method and Example 1 is that in step S1, 1.094 g Cu(NO3)2·3H2O, 1.317 g Zn(NO3)2·6H2O, 0.599 g Al(NO3)3·9H2O, 3 g melamine and 6 g soybean oil are ground evenly in an agate mortar.

[0043] The copper-based composite catalyst for methanol steam reforming to produce hydrogen prepared in this embodiment is labeled as catalyst 3. The mass percentage (wt%) of CuO:ZnO:Al2O3 in this catalyst is 44.78:45.09:10.13.

[0044] Example 4

[0045] This embodiment provides a method for preparing a highly dispersed copper-based composite catalyst for methanol steam reforming to produce hydrogen. The difference between this method and Example 1 is that in step S1, 1.635 g Cu(NO3)2·3H2O, 0.757 g Zn(NO3)2·6H2O, 0.599 g Al(NO3)3·9H2O, 3 g melamine and 6 g corn oil are ground evenly in an agate mortar.

[0046] The copper-based composite catalyst for methanol steam reforming to produce hydrogen prepared in this embodiment is designated as catalyst 4. The mass percentage (wt%) of CuO:ZnO:Al2O3 in this catalyst is 65.00:25.17:9.83.

[0047] Example 5

[0048] This embodiment provides a method for preparing a highly dispersed copper-based composite catalyst for methanol steam reforming to produce hydrogen. The difference between this method and Example 1 is that in step S1, 1.358 g Cu(NO3)2·3H2O, 1.043 g Zn(NO3)2·6H2O, 0.599 g Al(NO3)3·9H2O, 3 g melamine and 6 g rapeseed oil are ground evenly in an agate mortar.

[0049] The copper-based composite catalyst for methanol steam reforming to produce hydrogen prepared in this embodiment is designated as catalyst 5. The mass percentage (wt%) of CuO:ZnO:Al2O3 in this catalyst is 54.81:35.20:9.99.

[0050] Example 6

[0051] This embodiment provides a method for preparing a highly dispersed copper-based composite catalyst for methanol steam reforming to produce hydrogen. The difference between this method and Example 1 is that in step S1, 1.094 g Cu(NO3)2·3H2O, 1.317 g Zn(NO3)2·6H2O, 0.599 g Al(NO3)3·9H2O, 3 g melamine, 3 g rapeseed oil and 3 g corn oil are ground evenly in an agate mortar.

[0052] In this embodiment, a copper-based composite catalyst 6 for methanol steam reforming to produce hydrogen was prepared. The mass percentage (wt%) of CuO:ZnO:Al2O3 in this catalyst is 44.78:45.09:10.13.

[0053] Comparative Example 1

[0054] This embodiment provides a method for preparing a copper-based composite catalyst for methanol steam reforming to produce hydrogen. The difference between this method and Example 1 is that in step S1, 1.635 g Cu(NO3)2·3H2O, 0.757 g Zn(NO3)2·6H2O, 0.599 g Al(NO3)3·9H2O and 3 g melamine are ground evenly in an agate mortar.

[0055] The copper-based composite catalyst for methanol steam reforming to produce hydrogen prepared in this comparative example is designated as Comparative Example 1. The mass percentage (wt%) of CuO:ZnO:Al2O3 in this catalyst is 65.00:25.17:9.83.

[0056] Comparative Example 2

[0057] This embodiment provides a method for preparing a highly dispersed copper-based composite catalyst for methanol steam reforming to produce hydrogen. The difference between this method and Example 1 is that in step S1, 1.358 g Cu(NO3)2·3H2O, 1.043 g Zn(NO3)2·6H2O, 0.599 g Al(NO3)3·9H2O and 6 g soybean oil are ground evenly in an agate mortar.

[0058] The catalyst prepared in this comparative example is a copper-based composite catalyst for methanol steam reforming to produce hydrogen, denoted as Comparative Example 2. The mass percentage (wt%) of CuO:ZnO:Al2O3 in this catalyst is 54.81:35.20:9.99.

[0059] The performance of the catalysts prepared in the above embodiments and comparative examples for hydrogen production via methanol steam reforming was tested using the following methods:

[0060] The MSR reaction was carried out in a fixed-bed quartz reactor (500 mm in length and 10 mm in inner diameter) at one atmosphere. Before the reaction, 200 mg of catalyst (40-60 mesh) and 800 mg of quartz sand were uniformly mixed and loaded into the reactor for pre-reduction. A H2 / Ar (H2: 9.74%) mixed gas was introduced, and the temperature was raised from room temperature to 300 °C for reduction, and held at this temperature for 90 min. After reduction and activation, the H2 / Ar mixed gas was cut off, the temperature was set to the sampling point, and a mixed gas of methanol vapor, water vapor, and nitrogen was introduced at a flow rate of 70 ml / min, with a molar ratio of methanol to water vapor of 1:1.05. Six temperature sampling points were set in the 200-300 °C range: 200 °C, 220 °C, 240 °C, 260 °C, 280 °C, and 300 °C. Data were collected four times at each sampling point, and each sampling point was maintained for approximately 60 min. The heating time between each sampling point was 8 minutes, i.e., the heating rate was 2.5℃ / min, to test the performance of the methanol steam reforming hydrogen production catalyst.

[0061] See Figure 1 The image shows the XRD patterns of the catalysts prepared in Examples 1-6. Figure 1 As can be seen above, the catalyst samples prepared in Examples 1-6 exhibit characteristic diffraction peaks completely corresponding to ZnO (PDF#48-1548) at 2θ = 31.8°, 34.4°, 36.3°, 47.5°, and 56.6°. Simultaneously, characteristic peaks matching CuO (PDF#89-0510) are observed at 2θ = 32.5°, 35.5°, 38.7°, 48.7°, and 58.3°. Since Al2O3 in the catalyst is amorphous, its diffraction peaks are not visible in the XRD pattern.

[0062] Figure 2 These are comparative activity graphs of the catalysts prepared in Examples 1-6 and Comparative Examples 1-2. The graphs show that the catalysts prepared in this invention (Examples 1-6) exhibit significantly higher methanol conversion rates than Comparative Examples 1 and 2. The activity curve of Example 1 maintains the highest level across the entire temperature range (200-300°C), particularly at the critical process point of 250°C, where its conversion rate (approximately 95%) reaches an extremely high level. Comparative Examples 1 and 2, at the same temperature, may only achieve conversion rates of 40-50%, a substantial difference.

[0063] from Figure 3The selectivity spectra of the catalytic product H2 show that the hydrogen yields of the catalysts prepared in all embodiments of this invention are high, all above 75%, and the selectivity of the byproduct CO is also very low (<2%). This can be seen from its... Figure 4 This can be seen in the selective spectrum.

[0064] Figure 6 The figures show the nitrogen adsorption-desorption curves and pore size distribution of the catalysts in Examples 1-6. The figures show that the catalysts exhibit typical Type IV isotherms accompanied by H3-type hysteresis loops, which are typical characteristics of mesoporous materials. BET test results show that the specific surface areas of the catalysts in Examples 1-6 are 23 m² / g, 21 m² / g, 30 m² / g, 23 m² / g, 25 m² / g, and 30 m² / g, respectively, indicating that the catalysts have high specific surface areas. The BJH pore size distribution of the catalysts in Examples 1-6 is concentrated in the 20-40 nm range, which is mainly due to particle packing. Figure 5 This is further confirmed by the TEM image of Representative Example 1. This concentrated and uniform mesoporous structure provides a more uniform reaction environment, optimal mass transfer efficiency, and facilitates the rapid diffusion of reactants.

[0065] In summary, the preparation method provided by this invention involves mixing and grinding biomass raw materials (fatty acids) with industrial chemicals (melamine, nitrates) to form a homogeneous mixture. This mixture is then subjected to a two-step high-temperature calcination process (inert atmosphere pre-calcination and air atmosphere oxidation calcination) to obtain a copper-based composite catalyst for methanol reforming to hydrogen production with a large specific surface area and excellent dispersibility. Under an inert atmosphere, fatty acids carbonize to generate amorphous carbon, and nitrates decompose and reduce to metal / oxide nanoparticles. These nanoparticles are then interwoven with g-C3N4 produced by melamine decomposition, effectively inhibiting high-temperature agglomeration. Subsequent air calcination removes the amorphous carbon and g-C3N4, forming a porous structure rich in mesopores, resulting in high dispersion of metal oxides (CuO, ZnO, Al2O3). This structure significantly improves the adsorption and diffusion efficiency of reactants, achieving a methanol conversion rate of over 95% (250℃), H2 selectivity exceeding 75%, and CO selectivity below 2%. This enables the simple industrial-scale preparation of a low-cost, high-efficiency methanol steam reforming catalyst for hydrogen production, better meeting the needs of low-cost, high-efficiency online hydrogen production.

[0066] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A simple preparation method of a high dispersibility copper-based composite catalyst for hydrogen production by methanol steam reforming, characterized by, The method comprises the following steps: S1. Put a measured amount of Cu(NO3)2·3H2O, Zn(NO3)2·6H2O, Al(NO3)3·9H2O, melamine and vegetable oil into a mortar and grind uniformly to form a mixture; S2. Transfer the mixture obtained in step S1 into a porcelain boat and place it in a tube furnace for calcination under an inert atmosphere. After calcination, naturally cool to room temperature to obtain a precursor powder; S3. Place the precursor powder obtained in step S2 in a muffle furnace for calcination under an air atmosphere. After calcination, naturally cool to room temperature to obtain a high-dispersity copper-based composite catalyst for hydrogen production by methanol steam reforming.

2. The simple preparation method of the high-dispersibility copper-based composite catalyst for hydrogen production by methanol steam reforming according to claim 1, characterized in that, In step S1, the amount of melamine added is 3 g, and the amount of fatty acid added is 6 g; the fatty acid is selected from one or a mixture of two of soybean oil, corn oil and rapeseed oil.

3. The simple preparation method of the high-dispersibility copper-based composite catalyst for hydrogen production by methanol steam reforming according to claim 1, characterized in that, In step S2, the calcination conditions are 2 ℃ / min heating to 600 ℃ under N2 atmosphere for 2 h.

4. The simple preparation method of the high-dispersibility copper-based composite catalyst for hydrogen production by methanol steam reforming according to claim 1, characterized in that, In step S3, the calcination conditions are 2 ℃ / min heating to 600 ℃ under air atmosphere for 6 h.

5. The simple preparation method of the high dispersion copper-based composite catalyst for hydrogen production by methanol steam reforming according to claim 1, characterized in that, In step S3, the composite catalyst prepared is composed of an active component and a carrier, the active component is CuO-ZnO, and the carrier is Al2O3, wherein the mass percentage of CuO:ZnO:Al2O3 is 44.78-65.00:25.17-45.09:9.83-10.

13.

6. A high-dispersity copper-based composite catalyst for hydrogen production by methanol steam reforming, prepared by the preparation method of any one of claims 1-5.

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