Bifunctional composites, methods of making and using the same

Abstract

The present application relates to the field of bifunctional materials, and particularly relates to a kind of bifunctional composite material and its preparation method and application, the bifunctional composite material includes porous adsorbent and metal oxide;The metal oxide is adsorbed in the surface and pore of the porous adsorbent;Wherein, the porous adsorbent includes calcium oxide;The metal oxide includes nickel oxide and the oxide of metal element M, the metal element M is selected from at least one element in Ru, Rh, Pd, Os, Ir, Pt, Au and Ag.The bifunctional composite material of the present application has significantly improved catalytic adsorption effect.

Description

Technical Field

[0001] This invention relates to the field of bifunctional materials, specifically to a bifunctional composite material, its preparation method, and its application. Background Technology

[0002] CO2 can be captured from the waste gases of most existing industrial processes and converted into useful products in the presence of appropriate catalysts. Traditional carbon dioxide capture and utilization (CCU) technologies mainly focus on carbon capture and CO2 catalytic conversion processes separately, with these two relatively independent processes combined through gas storage and transportation. However, processes such as CO2 adsorbent regeneration, gas cooling and compression storage and transportation, and reheating catalysis significantly reduce the overall energy efficiency, severely hindering the widespread adoption of CCU technology. Developing a CO2 capture and in-situ hydrogenation conversion technology route, coupling carbon capture and catalytic conversion into an integrated process, can directly eliminate intermediate steps such as temperature and pressure-switching storage and transportation, and achieve adsorbent regeneration and CO2 catalytic conversion in situ under isothermal conditions. Therefore, it is necessary to develop double-functional materials (DFMs) to couple CO2 capture with the direct catalytic conversion of captured CO2, thereby solving the problems associated with existing CCU technologies.

[0003] Distillation fuel cells (DFMs) contain a CO2 adsorbent and catalyst, capable of effectively adsorbing and converting CO2 from flue gas. Introducing hydrogen from renewable energy sources into CO2-saturated DFMs causes CO2 molecules to overflow to catalyst sites, where they are converted into value-added chemicals. CaO is widely used as an adsorbent in DFMs due to its high adsorption capacity, rapid adsorption kinetics, and readily available raw materials. Nickel-based catalysts, with their abundant reserves, low cost, and high activity, are commonly used at the catalytic active sites of DFMs.

[0004] Bifunctional materials are typically prepared using solvothermal, hydrothermal, sol-gel, and impregnation methods. However, all of these methods suffer from drawbacks such as high equipment requirements, cost, complex and time-consuming processes, difficulty in controlling product uniformity, and environmental impact. Solvothermal and hydrothermal synthesis require high-pressure sealed containers, resulting in high equipment costs and safety hazards. Crystallinity is significantly affected by temperature gradients, making product control difficult. Sol-gel methods use expensive precursors and have long aging periods. Impregnation methods often result in uneven distribution of active ingredients, require multiple impregnations, are time-consuming, have limited loading capacity, are prone to detachment, and exhibit poor process stability. Furthermore, in practical applications, Ni catalysts exposed to flue gas containing large amounts of oxygen and H2O undergo oxidation reactions. In ICCU (Integrated Carbon Dioxide Capture and Utilization) methanation processes, the reaction temperature is generally controlled below 400℃, preventing NiO from being reduced to its active state. Summary of the Invention

[0005] In view of this, the present invention aims to provide a bifunctional composite material, its preparation method and application, in order to solve the problems of high equipment requirements, cost, complex and time-consuming processes, and difficulty in controlling product uniformity in the existing bifunctional materials.

[0006] To solve the above-mentioned technical problems, the present invention is implemented as follows:

[0007] A first aspect of the present invention provides a bifunctional composite material comprising a porous adsorbent material and a metal oxide; wherein the metal oxide is adsorbed on the surface and within the pores of the porous adsorbent material;

[0008] The porous adsorbent material includes calcium oxide;

[0009] The metal oxide includes nickel oxide and an oxide of metal element M, wherein the metal element M is selected from at least one element selected from Ru, Rh, Pd, Os, Ir, Pt, Au, and Ag.

[0010] Optionally, the specific surface area of ​​the porous adsorbent material is 20~80m². 2 / g, preferably 45~75m 2 / g; the pore volume of the porous adsorbent material is 0.02~1cm³. 3 / g, preferably 0.05~1cm 3 / g; the pore size of the porous adsorbent material is 1~80nm, preferably 2~70nm; the Dv50 of the bifunctional composite material is 10~100 nm, preferably 20~80 nm.

[0011] Optionally, based on the molar amount of calcium in the porous adsorption material, the content of the oxide of the metal element M is ≤5 mol%, and the content of nickel oxide is 1~15 mol%.

[0012] Optionally, the metallic element M is Ru.

[0013] A second aspect of the present invention provides a method for preparing a bifunctional composite material, the method comprising:

[0014] S1. The first active precursor is calcined to obtain the first intermediate.

[0015] S2. The second active precursor is mixed with a dispersant to obtain the second intermediate;

[0016] S3. The first intermediate and the second intermediate are subjected to a first mixing treatment and a calcination treatment;

[0017] The first active precursor includes calcium carbonate and calcium hydroxide;

[0018] The second active precursor includes a nickel-containing compound and a compound containing a metal element M; the metal element M is selected from at least one element selected from Ru, Rh, Pd, Os, Ir, Pt, Au and Ag.

[0019] Optionally, in the first active precursor, the mass ratio of calcium carbonate to calcium hydroxide is 1:(0.066~1.06); based on the molar amount of Ca in the first intermediate, the content of the metal element M is ≤5 mol%; and the content of nickel in the nickel-containing compound is 1~15 mol.

[0020] Optionally, the dispersant includes ethylene glycol, ethanol, and polyvinylpyrrolidone; the nickel-containing compound includes at least one of nickel nitrate hexahydrate, nickel acetate, nickel chloride hexahydrate, nickel sulfate hexahydrate, and nickel ammonium sulfate; the compound containing metal element M includes at least one of the halides, nitrates, sulfates, and organic acid salts of metal element M; preferably, the metal element M is Ru; the compound containing metal element M includes at least one of ruthenium trichloride, ruthenium nitrate, ruthenium sulfate (Ru2(SO4)3), and ruthenium oxalate (RuC2O4).

[0021] Optionally, in step S1, the calcination conditions include: a calcination temperature of 500~900℃, a heating rate of 2~30℃ / min, and a calcination time of 1~4h; preferably, the calcination conditions include: a calcination temperature of 600~850℃, a heating rate of 5~15℃ / min, and a calcination time of 1~3h; in step S3, the first mixing treatment is a ball milling treatment, and the ball milling conditions include: a ball-to-material ratio of 2~0.1 and a rotation speed of 150~500 rpm; the calcination treatment is carried out in an aerobic atmosphere, and the calcination conditions include: a temperature of 300~800℃ and a time of 2~6h.

[0022] A third aspect of the present invention provides a method for catalytic adsorption of carbon dioxide, the method comprising:

[0023] Hydrogen gas is introduced into a reactor filled with catalytic adsorption material to reduce the catalytic adsorption material; after a first purging with inert gas, a first mixed gas is introduced into the reactor to carry out an adsorption reaction; after a second purging with the inert gas, hydrogen gas is introduced into the reactor to carry out a hydrogenation reaction.

[0024] The first mixed gas includes carbon dioxide and nitrogen.

[0025] The catalytic adsorption material includes the above-mentioned bifunctional composite material and / or the bifunctional composite material prepared according to the above-mentioned preparation method.

[0026] Optionally, the method includes one or more of the following features (1) to (5):

[0027] (1) The volume ratio of carbon dioxide to nitrogen in the first mixed gas is 1:(4~6.5);

[0028] (2) The conditions for the reduction reaction include: a temperature of 400~650℃, a time of 1~3h, and a gas flow rate of 40~60mL·min. -1 ;

[0029] (3) The inert gas includes at least one of nitrogen, argon, neon, helium, xenon and krypton;

[0030] (4) The conditions for the adsorption reaction include: a temperature of 500~650℃, a time of 10~60min, and a gas flow rate of 40~120mL·min. -1 ;

[0031] (5) The conditions for the hydrogenation reaction include: a temperature of 400~600℃, a time of 10~60min, and a gas flow rate of 40~60mL·min. -1 .

[0032] The beneficial technical effects of the present invention through the above technical solution are as follows:

[0033] (1) The bifunctional composite material of the present invention includes a porous adsorbent material and a metal oxide adsorbed on the surface and within the pores of the porous adsorbent material. The porous adsorbent material has a channel structure that facilitates the entry of active particles or ions into the channels and their stable existence within the channels. The incorporation of noble metal M can improve the low-temperature reactivity of the nickel-based material, increase Ni dispersion, or change the reaction pathway to improve reactivity, stability, and resistance to carbon deposition and deactivation. Specifically, after doping with noble metal M, the interaction between noble metal M and Ni may alter the electronic structure of Ni. This change in electronic structure may make Ni ions easier to reduce, thereby improving the reducibility of Ni.

[0034] (2) The preparation method of the present invention prepares a first intermediate with specific channels by calcining the first active precursor, thereby ensuring the stable existence of active particles or ions and facilitating the dispersion of atoms or ions to obtain higher reaction activity. The preparation method of the present invention uses a dispersant to highly disperse the metal element M in the bifunctional material, and achieves atomic diffusion and alloying reaction through a further first mixing treatment, promoting efficient Ni-M synergy and improving the adsorption and in-situ catalytic conversion performance of the bifunctional material. Compared with the traditional impregnation method, the present invention uses a first mixing treatment to mix the first intermediate with a compound of a low-melting-point catalytically active element. During the mixing treatment, the first intermediate (calcium source) and nickel are subjected to mechanical force, resulting in a slight adjustment or optimization of the pore structure of the calcium source. This adjustment can increase the dispersion and uniformity of the catalytically active metal inside the calcium source. This special preparation method improves the synergistic effect of adsorption sites and catalytic sites in the catalytic conversion process, and also avoids reactor corrosion and energy consumption in the high-temperature evaporation process during wet impregnation.

[0035] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0036] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof.

[0037] Figure 1 The diagram shown is a structural schematic of the bifunctional composite material of the present invention. Detailed Implementation

[0038] This invention discloses a bifunctional composite material, its preparation method, and its applications. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0039] In the description of this invention, the list of items connected by the term "at least one of" or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0040] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges or individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0041] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0042] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0043] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0044] To address the problems of high equipment requirements, high cost, complex and time-consuming processes, and difficulty in controlling product uniformity in existing bifunctional materials, this invention adopts the following technical solution:

[0045] The first aspect of the present invention provides a bifunctional composite material, such as Figure 1 As shown, the bifunctional composite material comprises a porous adsorbent material and a metal oxide; the metal oxide is adsorbed on the surface and within the pores of the porous adsorbent material.

[0046] The porous adsorbent material includes calcium oxide;

[0047] The metal oxide includes nickel oxide and an oxide of metal element M, wherein the metal element M is selected from at least one element selected from Ru, Rh, Pd, Os, Ir, Pt, Au, and Ag.

[0048] The bifunctional composite material of this invention comprises a porous adsorbent material and a metal oxide adsorbed on the surface and within the pores of the porous adsorbent material. The porous structure of the adsorbent material facilitates the entry and stable presence of active particles or ions within the pores. The incorporation of the noble metal M can enhance the low-temperature reactivity of the nickel-based material, increase Ni dispersion, or alter the reaction pathway to improve reactivity, stability, and resistance to carbon deposition and deactivation. Specifically, doping with the noble metal M may alter the electronic structure of Ni due to the interaction between M and Ni. This change in electronic structure may make Ni ions easier to reduce, thereby improving the reducibility of Ni.

[0049] In this invention, the porous adsorbent material has a significantly increased specific surface area, which enables it to have a higher adsorption capacity. In some embodiments, the specific surface area of ​​the porous adsorbent material can be 20-80 m². 2 / g. For example, the specific surface area of ​​the porous adsorbent material can be 25m². 2 / g、35m 2 / g、45m 2 / g、55m 2 / g、65m 2 / g and 75m 2 Any value in / g or any value within the range formed by any two of the above values. In a preferred embodiment, the specific surface area of ​​the porous adsorbent material is 45~75m². 2 / g.

[0050] According to the present invention, if the pore volume of the porous adsorbent material is too large, it may reduce the specific surface area of ​​the porous adsorbent material, leading to a decrease in the density of surface active sites. Studies have shown that adsorption performance is mainly contributed by micropores and mesopores, while macropores mainly serve as gas diffusion channels. If the pore volume is too large but the pore size distribution is unreasonable, it will weaken the adsorption capacity. If the pore volume of the porous adsorbent material is too small, it may lead to more particle agglomeration and sintering at high temperatures, resulting in pore closure and rapid decay of adsorption performance. In some embodiments, the pore volume of the porous adsorbent material can be 0.02~1 cm³. 3 / g. For example, the pore volume of the porous adsorbent material can be 0.025 cm³. 3 / g, 0.05cm 3 / g, 0.1cm 3 / g, 0.2cm 3 / g, 0.4cm 3 / g and 0.8cm 3 Any value in / g or any value within the range formed by any two of the above values. In a preferred embodiment, the pore volume of the porous adsorbent material is 0.05~0.1cm³.3 / g, the porous adsorbent material in this preferred embodiment has significantly improved anti-sintering and adsorption effects.

[0051] In some embodiments, the pore size of the porous adsorbent material can be 1-80 nm. Exemplarily, the pore size of the porous adsorbent material can be any value selected from 1 nm, 10 nm, 20 nm, 40 nm, 60 nm, and 80 nm, or any value within a range formed by any pair of the above values. In this invention, if the pore size of the porous adsorbent material is too large, it may sacrifice specific surface area and selectivity; if the pore size of the porous adsorbent material is too small, it may hinder the diffusion of CO2 molecules into the adsorbent, especially during high-temperature rapid adsorption, where the reaction rate is limited by diffusion. In a preferred embodiment, the pore size of the porous adsorbent material can be 2-70 nm.

[0052] In some embodiments, the Dv50 of the bifunctional composite material can be 10~100 nm. Exemplarily, the Dv50 of the bifunctional composite material can be any value selected from 10 nm, 20 nm, 40 nm, 60 nm, 80 nm, and 100 nm, or any value within the range formed by any pair of the aforementioned values. In a preferred embodiment, the Dv50 of the bifunctional composite material can be 20~80 nm.

[0053] According to the present invention, suitable porous adsorbent materials in bifunctional composite materials can achieve a balance between high specific surface area and low diffusion resistance. Micropores provide abundant surface active sites, significantly improving adsorption capacity; mesopores serve as gas diffusion channels, accelerating the transfer of CO2 molecules into the adsorbent. Furthermore, micropores and mesopores can achieve a synergistic effect, with micropores adsorbing gas molecules and mesopores promoting mass transfer. These features all help to avoid sintering of bifunctional materials at high temperatures due to excessively high local density and improve adsorption capacity.

[0054] In some embodiments, based on the molar amount of calcium in the porous adsorption material, the content of the oxide of the metal element M is ≤5 mol%. Exemplarily, based on the molar amount of calcium in the porous adsorption material, the content of the oxide of the metal element M can be any value from 0.01 mol%, 0.1 mol%, 1 mol%, 2 mol%, 4 mol%, and 5 mol%, or any value within the range of any pair of the above values. In this invention, if the content of the oxide of the metal element M is too high, it may cause the noble metal to cover the active sites of the Ca-Ni matrix, hindering the adsorption-activation of CO2 or reactant molecules; if the content of the oxide of the metal element M is too low, it may prevent the formation of a continuous catalytic network, thereby failing to improve catalytic conversion performance. In a preferred embodiment, based on the molar amount of calcium in the porous adsorption material, the content of the oxide of the metal element M is 0.5~4 mol%.

[0055] In some embodiments, the nickel oxide content is 1-15 mol%, based on the molar amount of calcium in the porous adsorbent material. Exemplarily, the nickel oxide content can be any value from 1 mol%, 3 mol%, 6 mol%, 9 mol%, 12 mol%, and 15 mol%, or any value within the range of any pair of values ​​mentioned above, based on the molar amount of calcium in the porous adsorbent material. In a preferred embodiment, the nickel oxide content is 1-10 mol%, based on the molar amount of calcium in the porous adsorbent material.

[0056] In a preferred embodiment of the present invention, the metal element M is Ru. Doping with the noble metal Ru can also increase the dispersion of Ni in the adsorbent. This is mainly because noble metal atoms can act as "anchors," helping Ni atoms to disperse better on the adsorbent support. Furthermore, doping with the noble metal Ru may also alter the chemical properties of the material surface, making it easier for Ni atoms to bind to the support, thereby further improving its dispersion. Highly dispersed Ni atoms can provide more active sites, which is beneficial for the catalytic reaction.

[0057] A second aspect of the present invention provides a method for preparing a bifunctional composite material, the method comprising:

[0058] S1. The first active precursor is calcined to obtain the first intermediate.

[0059] S2. The second active precursor is mixed with a dispersant to obtain the second intermediate;

[0060] S3. The first intermediate and the second intermediate are subjected to a first mixing treatment and a calcination treatment;

[0061] The first active precursor includes calcium carbonate and calcium hydroxide;

[0062] The second active precursor includes a nickel-containing compound and a compound containing a metal element M; the metal element M is selected from at least one element selected from Ru, Rh, Pd, Os, Ir, Pt, Au and Ag.

[0063] The preparation method of this invention involves calcining a first active precursor to obtain a first intermediate with specific pores, thereby ensuring the stable existence of active particles or ions (e.g., nickel and noble metals), facilitating the dispersion of atoms or ions to achieve higher reactivity. This method uses a dispersant to highly disperse the metal element M in the bifunctional material, and further employs a first mixing treatment to achieve atomic diffusion and alloying reactions, promoting efficient Ni-M synergy and improving the adsorption and in-situ catalytic conversion performance of the bifunctional material. Compared to the traditional impregnation method, this invention uses a first mixing treatment to mix the first intermediate with a compound of a low-melting-point catalytically active element. During the mixing process, the first intermediate (calcium source) and nickel are subjected to mechanical forces, resulting in a slight adjustment or optimization of the pore structure of the calcium source. This adjustment increases the dispersion and uniformity of the catalytically active metal within the calcium source. This unique preparation method improves the synergistic effect between adsorption and catalytic sites during catalytic conversion and avoids reactor corrosion and energy consumption during high-temperature evaporation in wet impregnation processes.

[0064] In this invention, a suitable ratio of calcium carbonate to calcium hydroxide in the first active precursor enables the prepared bifunctional composite material to possess a rich and suitable pore structure. If the calcium carbonate content in the first active precursor is too high, the violent gas escape during calcination and decomposition may lead to excessive pore expansion, forming a macroporous structure with uneven pore size distribution. Such loose pores are prone to collapse during subsequent use or recycling. If the calcium carbonate content in the first active precursor is too low, the amount of CO2 gas generated during decomposition may be insufficient, resulting in a dense pore structure with narrow pore size, which will hinder the diffusion of gas molecules and reduce reaction kinetics. In some embodiments, the mass ratio of calcium carbonate to calcium hydroxide in the first active precursor is 1:(0.066~1.06). Exemplarily, the mass ratio of calcium carbonate to calcium hydroxide in the first active precursor can be any value among 1:0.066, 1:0.133, 1:0.266, 1:0.532, and 1:1.06, or any value within the range of any two of the above values.

[0065] In some embodiments, based on the molar amount of Ca in the first intermediate, the content of the metal element M, in terms of elements, is ≤5 mol%; exemplarily, based on the molar amount of Ca in the first intermediate, the content of the metal element M, in terms of elements, can be any value among 0.01 mol%, 0.1 mol%, 1 mol%, 2 mol%, 4 mol%, and 5 mol%, or any value within the range of any pair of the above values.

[0066] In some embodiments, based on the molar amount of Ca in the first intermediate, the nickel content in the nickel-containing compound is 1 to 15 mol%. For example, based on the molar amount of Ca in the first intermediate, the nickel content in the nickel-containing compound can be any value from 0.01 mol%, 0.1 mol%, 1 mol%, 2 mol%, 4 mol%, and 5 mol%, or any value within the range of any pair of the above values.

[0067] For example, the dispersant may include ethylene glycol, ethanol, and polyvinylpyrrolidone.

[0068] For example, the nickel-containing compound may include at least one of nickel nitrate hexahydrate, nickel acetate, nickel chloride hexahydrate, nickel sulfate hexahydrate, and nickel ammonium sulfate.

[0069] For example, the compound containing metal element M may include at least one of the following: halide, nitrate, sulfate and organic acid salt of metal element M; preferably, metal element M is Ru.

[0070] For example, the compound containing the metal element M may include at least one of ruthenium trichloride, ruthenium nitrate, ruthenium sulfate (Ru2(SO4)3), and ruthenium oxalate (RuC2O4).

[0071] In step S1 of this invention, an excessively rapid heating rate during the calcination process may lead to pore collapse or local shrinkage, while an excessively slow rate may promote particle fusion and reduce the specific surface area. In an embodiment of this invention, the calcination process is carried out in an aerobic atmosphere; the conditions for the calcination process include: a calcination temperature of 500~900℃, a heating rate of 2~30℃ / min, and a calcination time of 1~4h; preferably, the conditions for the calcination process include: a temperature of 600~850℃, a heating rate of 5~15℃ / min, and a time of 1~3h.

[0072] In an embodiment of the present invention, in step S3, the first mixing treatment can be ball milling, and the conditions of the ball milling treatment can include: a ball-to-material ratio of 0.1 to 2 and a rotation speed of 150 to 500 rpm; the calcination treatment can be carried out in an aerobic atmosphere, and the conditions of the calcination treatment can include: a temperature of 300 to 800°C and a time of 2 to 6 hours.

[0073] The oxygen atmosphere involved in this invention can be at least one of air, nitrogen, carbon dioxide and hydrogen.

[0074] A third aspect of the present invention provides a method for catalytic adsorption of carbon dioxide, the method comprising:

[0075] Hydrogen gas is introduced into a reactor filled with catalytic adsorption material to reduce the catalytic adsorption material; after a first purging with inert gas, a first mixed gas is introduced into the reactor to carry out an adsorption reaction; after a second purging with the inert gas, hydrogen gas is introduced into the reactor to carry out a hydrogenation reaction.

[0076] The first mixed gas includes carbon dioxide and nitrogen.

[0077] The catalytic adsorption material includes the above-mentioned bifunctional composite material and / or the bifunctional composite material prepared according to the above-mentioned preparation method.

[0078] In some embodiments, the volume ratio of carbon dioxide to nitrogen in the first mixed gas can be 1:(4~6.5).

[0079] In some embodiments, the conditions for the reduction reaction may include: a temperature of 400–650 °C, a time of 1–3 h, and a gas flow rate of 40–60 mL / min. -1 .

[0080] In some embodiments, the inert gas may include at least one of nitrogen, argon, neon, helium, xenon, and krypton.

[0081] In some embodiments, the conditions for the adsorption reaction may include: a temperature of 500–650 °C, a time of 10–60 min, and a gas flow rate of 40–120 mL / min. -1 .

[0082] In some embodiments, the conditions for the hydrogenation reaction may include: a temperature of 400–600 °C, a time of 10–60 min, and a gas flow rate of 40–60 mL / min. -1 .

[0083] The present invention will be further described in detail below through examples. All raw materials used in the examples are commercially available.

[0084] Example 1

[0085] 15.8 g of calcium carbonate and 4.2 g of calcium hydroxide were weighed and placed in a muffle furnace for calcination to obtain the first intermediate. The calcination conditions included heating to 850 °C at a rate of 10 °C / min and holding at that temperature for 2 hours. 0.973 g of nickel nitrate hexahydrate and 0.156 g of ruthenium trichloride were dissolved in ethylene glycol to obtain the second intermediate.

[0086] The second intermediate was completely added to 5g of intermediate 1 and mixed, then ball-milled at a ball-to-material ratio of 0.5 and a rotation speed of 300 rpm. The ball-milled mixture was then placed in a muffle furnace for calcination to obtain the bifunctional composite material of this embodiment. The calcination conditions included heating to 600°C at a heating rate of 5°C / min and holding at that temperature for 5 hours.

[0087] Example 2

[0088] The preparation method of the bifunctional composite material in this embodiment is the same as that in Example 1, except that 0.973g of nickel nitrate hexahydrate and 0.078g of ruthenium trichloride are dissolved in ethylene glycol to obtain the second intermediate.

[0089] Example 3

[0090] The preparation method of the bifunctional composite material in this embodiment is the same as that in Example 1, except that the temperature is raised to 600°C at a heating rate of 20°C / min and then held for 5 hours.

[0091] Example 4

[0092] The preparation method of the bifunctional composite material in this embodiment is the same as that in Example 1, except that 0.973g of nickel nitrate hexahydrate and 0.148g of platinum tetrachloride are dissolved in ethylene glycol to obtain the second intermediate.

[0093] Example 5

[0094] The preparation method of the bifunctional composite material in this embodiment is the same as that in Embodiment 1, except that 4.2g of calcium carbonate and 15.8g of calcium hydroxide are weighed and placed in a muffle furnace for calcination to obtain the first intermediate.

[0095] Comparative Example 1

[0096] The preparation method of the bifunctional composite material in this comparative example is the same as that in Example 1, except that 20g of calcium carbonate is weighed and placed in a muffle furnace for calcination to obtain the first intermediate.

[0097] Comparative Example 2

[0098] The preparation method of the bifunctional composite material in this comparative example is the same as that in Example 1, except that 0.973g of nickel nitrate hexahydrate is dissolved in ethylene glycol to obtain the second intermediate.

[0099] Comparative Example 3

[0100] 15.8 g of calcium carbonate and 4.2 g of calcium hydroxide were weighed and placed in a muffle furnace for calcination to obtain the first intermediate. The calcination conditions included heating to 850 °C at a rate of 10 °C / min and holding at that temperature for 2 hours. 0.973 g of nickel nitrate hexahydrate and 0.078 g of ruthenium trichloride were dissolved in 16 mL of deionized water to obtain the first solution.

[0101] 5g of the first intermediate was mixed with the first solution to obtain the first material, wherein the mixing temperature was 25℃ and the mixing time was 12h. The first material was evaporated to dryness while stirring at 90℃, and then dried overnight in an oven at 130℃. The dried sample was ground into powder and calcined in a muffle furnace to obtain the bifunctional composite material of this comparative example. The calcination conditions included heating to 600℃ at a heating rate of 5℃ / min and holding at that temperature for 5h.

[0102] Test Example 1

[0103] The bifunctional composite materials prepared in Examples 1-5 and Comparative Examples 1-2 were analyzed, and the results are shown in Table 1. The specific surface area, pore volume, and pore size of the porous adsorbent were determined by BET specific surface area testing, and the Dv50 of the bifunctional composite material was determined by laser diffraction.

[0104] Table 1. Analytical results of bifunctional composite materials

[0105]

[0106] Test Example 2

[0107] The bifunctional composite materials prepared in Examples 1-5 and Comparative Examples 1-2 were molded using a tablet press and then subjected to performance tests on a fixed bed. The test results are shown in Table 2. The specific test methods are as follows:

[0108] Mix 0.5g of catalyst (40-60 mesh) with 0.5g of inert quartz sand, load the mixture into a reaction tube, and place it into the reactor. The reactor temperature is controlled by an intermediate thermocouple. The catalyst is incubated in H2 (50mL·min⁻¹). -1 In a gas at 550℃ (heating rate of 2℃·min) -1 Reduction was performed at a certain temperature. After reduction, the reactor was purged under an N2 atmosphere for 5 min, followed by the introduction of a mixed reaction gas of CO2 (15%, v / v) and N2 (85%, v / v) at a total flow rate of 100 mL / min. -1The reactor was introduced under the specified conditions and maintained for 30 min to carry out the adsorption phase reaction. After adsorption, the temperature was increased to 85 mL / min. -1 Purge under a pure N2 atmosphere for 5 min. After purging, switch the gas to H2 (50 mL / min). -1 Add hydrogen for 30 min. All the above product gases were collected by a gas bag and analyzed offline by gas chromatography (GC, Fuli Instruments, 9700) equipped with a thermal conductivity detector for H2, CO, CH4, and CO2.

[0109] Table 2 Performance test results of bifunctional composite materials

[0110]

[0111] As can be seen from Table 1, the bifunctional composite materials prepared in Examples 1-5 achieved improvements in adsorption capacity, conversion rate, and selectivity.

[0112] The pore structure results of Example 1 and Comparative Example 1 show that the specific surface area of ​​the first intermediate produced by calcining single calcium carbonate is smaller than that of Example 1, but the pore size of Comparative Example 1 is larger than that of Example 1. This is mainly because the release of CO2 during the decomposition of CaCO3 promotes the formation of macropores, but the specific surface area contributed by macropores is relatively low, resulting in a slightly lower overall specific surface area. Differences in pore structure affect the distribution of nickel and ruthenium catalytic sites, as well as the particle size of the final bifunctional material. A suitable pore structure can effectively disperse active sites, making them less prone to aggregation, thereby resulting in a smaller particle size of the final bifunctional material. Dispersed catalytic active sites and small particle size can both achieve high catalytic conversion performance, as shown in Example 1.

[0113] A comparison of the results of Example 1 and Comparative Example 2 shows that the catalytic conversion performance in the absence of ruthenium is much lower than that in the presence of ruthenium. This is mainly because Ru doping can increase the dispersion of Ni in the adsorbent, thereby improving the catalytic activity.

[0114] As shown in Example 1 and Comparative Example 3, the wet ball milling process is superior to the impregnation method. The bifunctional material prepared by the impregnation method has a very large particle size, indicating severe agglomeration. Particle agglomeration reduces the adsorption and catalytic conversion activity of the bifunctional material, therefore its adsorption capacity and catalytic conversion performance are not as good as those in Example 1.

[0115] The pore structure results of Examples 1 and 5 show that when the Ca(OH)₂ content is too high, the specific surface area, pore volume, and pore size are all smaller than in Example 1. This is mainly because the amount of gas released by water vapor is less than that from the decomposition of calcium carbonate, and the resulting pores are smaller and more dense. Similarly, the adsorption capacity and catalytic conversion performance of Example 5 are not as good as those of Example 1.

[0116] A comparison of the results from Examples 1 and 4 shows that, with the same adsorption site composition, changing the type of noble metal has little effect on the adsorption amount, but the catalytic conversion performance decreases. This is mainly because platinum is more prone to agglomeration into large particles than ruthenium, reducing dispersion.

[0117] A comparison of Example 1 and Example 3 shows that an excessively rapid heating rate leads to a decrease in specific surface area and an increase in pore volume. This is because the violent escape of gases (CO2 and H2O) easily forms large pores, thus increasing the total pore volume. Furthermore, the number of micropores and mesopores in the material decreases, resulting in a significant reduction in specific surface area. For adsorption sites, excessively large pore sizes are not conducive to adsorption, therefore the adsorption capacity is lower than in Example 1. In addition, large pore sizes cannot provide sufficient surface defects or chemical bonding sites to anchor metal particles, causing particles to tend to aggregate in low-curvature regions. Therefore, its catalytic conversion performance is also far inferior to that of Example 1.

[0118] A comparison of Example 1 and Example 2 shows that 1% RuO2 is the optimal loading. When the Ru content is too high, Ru particles migrate and agglomerate due to supersaturation, and the agglomerated nanoparticles block the CaO channels. Compared to a loading of 2% RuO2, 1% RuO2 promotes greater dispersion of nickel and ruthenium, resulting in higher catalytic conversion performance, and the dispersed metals do not block the pore structure; therefore, the adsorption capacity is also greater than in Example 1.

[0119] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A bifunctional composite material, characterized in that, The bifunctional composite material comprises a porous adsorbent material and a metal oxide; the metal oxide is adsorbed on the surface and in the pores of the porous adsorbent material; The porous adsorbent material comprises calcium oxide; The metal oxide comprises nickel oxide and an oxide of a metal element M, the metal element M being selected from at least one element of Ru, Rh, Pd, Os, Ir, Pt, Au and Ag; The porous adsorbent material has a pore volume of 0.53 to 1 cm 3 / g; The pore size of the porous adsorbent material is 20-80 nm; The preparation method of the bifunctional composite material comprises: S1, roasting a first active precursor to obtain a first intermediate; S2, mixing a second active precursor with a dispersant to obtain a second intermediate; S3, performing first mixing treatment and calcination treatment on the first intermediate and the second intermediate; The first active precursor comprises calcium carbonate and calcium hydroxide; the second active precursor comprises a nickel-containing compound and a compound containing a metal element M; In step S3, the first mixing treatment is ball milling treatment, the ball milling treatment conditions include: the ball-to-material ratio is 0.1-2, and the rotation speed is 150-500 rmp; the calcination treatment is performed in an oxygen atmosphere, and the calcination treatment conditions include: the temperature is 300-800 DEG C, and the time is 2-6 h.

2. The bifunctional composite material according to claim 1, characterized in that, The specific surface area of the porous adsorbent material is 20-80 m 2 / g; The Dv50 of the bifunctional composite material is 10-100 nm.

3. The bifunctional composite material of claim 1, wherein, The content of the oxide of the metal element M is ≤5 mol %, and the content of the nickel oxide is 1-15 mol %, based on the molar amount of calcium element in the porous adsorbent material.

4. The bifunctional composite material of claim 1, wherein, The metal element M is Ru.

5. A method for producing the bifunctional composite material according to any one of claims 1 to 4, characterized by, The preparation method comprises: S1, roasting a first active precursor to obtain a first intermediate; S2, mixing a second active precursor with a dispersant to obtain a second intermediate; S3, performing first mixing treatment and calcination treatment on the first intermediate and the second intermediate; The first active precursor comprises calcium carbonate and calcium hydroxide; The second active precursor comprises a nickel-containing compound and a compound containing a metal element M, the metal element M being selected from at least one element of Ru, Rh, Pd, Os, Ir, Pt, Au and Ag.

6. The production method according to claim 5, wherein In the first active precursor, the mass ratio of the calcium carbonate to the calcium hydroxide is 1: (0.066-1.06); The content of the metal element M is ≤5 mol %, and the content of the nickel element in the nickel-containing compound is 1-15 mol %, based on the molar amount of Ca in the first intermediate.

7. The preparation method according to claim 5, characterized in that, The dispersant comprises ethylene glycol, ethanol and polyvinylpyrrolidone; The nickel-containing compound comprises at least one of nickel nitrate hexahydrate, nickel acetate, nickel chloride hexahydrate, nickel sulfate hexahydrate and nickel ammonium sulfate; The compound containing the metal element M comprises at least one of a halide, a nitrate, a sulfate and an organic acid salt of the metal element M.

8. The preparation method according to claim 5, characterized in that, In step S1, the calcination treatment is performed in an oxygen atmosphere; the conditions of the calcination treatment include: a calcination temperature of 500-900℃, a temperature rising rate of 2-30℃ / min, and a calcination time of 1-4h; In step S3, the first mixing treatment is a ball milling treatment, the conditions of the ball milling treatment include: a ball-to-material ratio of 0.1-2 and a rotating speed of 150-500rmp; the calcination treatment is performed in an oxygen atmosphere, and the conditions of the calcination treatment include: a temperature of 300-800℃ and a time of 2-6h.

9. A method of carbon dioxide catalytic adsorption, characterized by, The method comprises: passing hydrogen into a reactor filled with the catalytic adsorption material to perform a reduction reaction on the catalytic adsorption material; after passing an inert gas into the reactor to perform a first purging, passing a first mixed gas into the reactor to perform an adsorption reaction; after passing the inert gas into the reactor to perform a second purging, passing hydrogen into the reactor to perform a hydrogenation reaction; wherein the first mixed gas comprises carbon dioxide and nitrogen; the catalytic adsorption material comprises the bifunctional composite material according to any one of claims 1-4 and / or the bifunctional composite material prepared according to the preparation method of any one of claims 5-8.

10. The method of claim 9, wherein, The method comprises one or more of the following features (1)-(5): (1) the volume ratio of carbon dioxide to nitrogen in the first mixed gas is 1:(4-6.5); (2) the conditions of the reduction reaction include: temperature is 400~650℃, time is 1~3h, gas flow rate is 40~60 mL·min -1 ; (3) the inert gas comprises at least one of nitrogen, argon, neon, helium, xenon and krypton; (4) The conditions of the adsorption reaction include: temperature of 500-650℃, time of 10-60 min, gas flow rate of 40-120 mL·min -1 ; (5) The conditions of the hydrogenation reaction include: temperature of 400-600℃, time of 10-60 min, gas flow rate of 40-60 mL·min -1 .

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