A NiO-Ca9Co 12 O 28 Catalytic oxygen carrier, its preparation and application in alcohol reforming for hydrogen production

Abstract

The present invention belongs to the field of alcohol reforming, and particularly relates to a NiO-Ca9Co 12 O 28 oxygen carrier catalyst, which comprises NiO and Ca9Co 12 O 28 . The present invention also includes a preparation method of the oxygen carrier and a method for alcohol reforming and cyclic chain preparation. This method can not only operate autothermally, but also efficiently capture carbon dioxide and inhibit the formation of CO, so as to obtain high-quality hydrogen in one step. The designed NiO-Ca9Co 12 O 28 oxygen carrier catalyst maintains high cyclic stability through phase separation and recombination.

Description

Technical Field

[0001] The present invention relates to the technical fields of functional materials, energy conversion, and environmental protection, and particularly relates to a method for lattice oxygen-induced adsorption-enhanced ethanol reforming for hydrogen production. Background Art

[0002] With the increasingly severe problems of global warming, air pollution, energy shortage, etc., it is urgent to develop clean and pollution-free new energy. Hydrogen energy is regarded as the "ultimate energy" in the 21st century due to its advantages such as high combustion calorific value, pollution-free, renewable, and wide sources. Hydrogen has a low volume energy density, high liquefaction energy consumption, and is volatile under standard conditions, making it difficult to store and transport. Currently, the mainstream mobile hydrogen storage technologies still have a certain gap from the commercialization goal in terms of mass energy density, volume energy density, safety, cost, etc.

[0003] To solve the problems of hydrogen storage and transportation, using high-energy-density liquid lower alcohols as hydrogen energy carriers can achieve real-time reforming for hydrogen production. Among various lower alcohols, ethanol is the most potential renewable hydrogen source material, manifested in: (1) It can be produced on a large scale through the fermentation of biomass such as starch or sugars, with very wide sources and low prices; (2) It is convenient for storage and transportation and has low toxicity (without elements such as S and N); (3) It has a high H / C molar ratio, and 1 mol of ethanol can produce 6 mol of hydrogen under ideal conditions, with a high energy density.

[0004] The existing ethanol reforming for hydrogen production processes mainly focus on adsorption-enhanced ethanol steam reforming (SE-SRE) technology and chemical looping reforming (CLR) technology. SE-SRE is to add a CO2 adsorbent into the reactor to in-situ remove CO2, making the equilibrium of the ethanol reforming reaction and the water gas shift reaction (WGS: CO → CO2) shift towards the direction of hydrogen production, which is beneficial to increasing the hydrogen concentration and reducing the concentration of other by-products, and thus achieving the purpose of producing high-purity hydrogen in one step. However, since the traditional ethanol reforming technology cannot be self-heating, an obvious disadvantage after introducing the adsorption-enhanced technology is the high temperature requirement for the desorption and regeneration stage of the adsorbent, resulting in problems such as high energy consumption and material deterioration.

[0005] The chemical looping reforming technology uses the lattice oxygen of the oxygen carrier (metal oxide) to participate in the partial oxidation of the fuel to produce hydrogen, and the reduced metal oxide is regenerated by air and recycled. Self-heating is achieved through the redox reaction, reducing the reaction temperature required, and effectively reducing the reaction energy consumption. However, the chemical looping reforming technology cannot produce high-purity hydrogen, and subsequent complex and expensive separation steps are required. Summary of the Invention

[0006] To solve the problem that the existing means of alcohol reforming for hydrogen production have unsatisfactory hydrogen production and regeneration effects, the first object of the present invention is to provide a new NiO-Ca9Co 12 O 28Catalytic oxygen carriers, aiming to provide a catalytic oxygen carrier with excellent performance in alcohol reforming for hydrogen production.

[0007] The second object of the present invention is to provide the described NiO-Ca9Co 12 O 28 Preparation method of the catalytic oxygen carrier.

[0008] The third object of the present invention is to provide the application of the described NiO-Ca9Co 12 O 28 Catalytic oxygen carrier in alcohol reforming for hydrogen production and regeneration.

[0009] The fourth object of the present invention is to provide a lattice oxygen-induced adsorption-enhanced alcohol reforming for hydrogen production method based on NiO-Ca9Co 12 O 28 Catalytic oxygen carrier, aiming to realize the chemical looping reaction of alcohol to hydrogen through the described NiO-Ca9Co 12 O 28 Catalytic oxygen carrier.

[0010] A NiO-Ca9Co 12 O 28 Catalytic oxygen carrier, including NiO and Ca9Co 12 O 28 .

[0011] The present invention studies and finds that the combination of NiO and Ca9Co 12 O 28 can induce the formation of Ni-Co alloy structure in the alcohol catalytic reforming stage. Thus, it can unexpectedly significantly improve the activation energy of alcohol reforming for hydrogen production, and can realize the effective hydrogen production of alcohol at a lower temperature, improve the hydrogen production efficiency and hydrogen production rate. In addition, it also helps to adsorb carbon dioxide in the hydrogen production stage, which is beneficial to obtaining high-purity hydrogen.

[0012] In the present invention, the described Ca9Co 12 O 28 is a lamellar structure material.

[0013] In the present invention, the described NiO is preferably nano-sized particles.

[0014] Preferably, in the NiO-Ca9Co 12 O 28 catalytic oxygen carrier, with Ca9Co 12 O 28 as the substrate, the described NiO is uniformly dispersed therein. The present invention studies and finds that loading NiO on Ca9Co 12 O 28In the substrate, it helps to further improve the synergy between the two and also helps to further improve its performance in alcohol reforming for hydrogen production and regeneration.

[0015] More preferably, the NiO is uniformly dispersed in the Ca9Co 12 O 28 substrate in situ;

[0016] The research of the present invention finds that further controlling the ratio of NiO-Ca9Co 12 O 28 helps to further synergistically improve its performance in alcohol reforming for hydrogen production and regeneration.

[0017] Preferably, in the NiO and Ca9Co 12 O 28 the percentage of Ni in the total molar amount of Ni, Co and Ca elements is greater than 0% and less than or equal to 20%; preferably 5-15%; more preferably 9-11%.

[0018] The present invention also provides a preparation method of the NiO-Ca9Co 12 O 28 catalytic oxygen carrier, which is obtained by compounding NiO and Ca9Co 12 O 28 .

[0019] A preferred preparation method of the NiO-Ca9Co 12 O 28 catalytic oxygen carrier of the present invention is obtained by carrying out a sol-gel reaction with a nickel source, a calcium source, a cobalt source and a complexing carbon source, drying the obtained gel to obtain a precursor, and then calcining the precursor.

[0020] Preferably, the nickel source, calcium source and cobalt source are at least one of water-soluble salts, oxides and hydroxides of their respective metal elements. The water-soluble salts are, for example, at least one of chlorides, sulfates and organic acid salts.

[0021] Preferably, the complexing carbon source is at least one of citric acid, citrate and ethylene glycol;

[0022] Preferably, in the nickel source, calcium source and cobalt source, the percentage of Ni in the total molar amount of Ni, Co and Ca elements is greater than 0% and less than or equal to 20%; preferably 5-15%.

[0023] Preferably, the ratio of the complexing carbon source to the total molar amount of Ni, Co and Ca elements in the raw materials is 1-1.5:1, and more preferably 1.1-1.3:1.

[0024] In the present invention, the solvent for the gel-sol reaction is, for example, water or a mixed solvent of water-organic solvent, and the organic solvent is, for example, a solvent miscible with water, such as ethanol, acetone, etc.

[0025] In the present invention, the obtained gel is dried to obtain a precursor. The drying temperature is, for example, 100-200 °C; the drying time is based on reaching constant weight. The drying temperature is 140-160 °C. In the present invention, the gel desolvates, foams and ages during the drying stage. Preferably, the drying time is 3-5 h. In the present invention, the drying stage can be carried out in a forced-air drying oven, and there is no special requirement for its atmosphere. For example, it can be an air atmosphere.

[0026] In the present invention, the precursor is calcined. Among them, the calcination atmosphere is an oxygen-containing atmosphere; for example, at least one of oxygen, air, oxygen-nitrogen mixture, oxygen-inert gas mixture.

[0027] Preferably, the temperature in the calcination stage is 750-900 °C, and more preferably 800-850 °C;

[0028] Preferably, the calcination time is 2-6 h, and more preferably 3-5 h.

[0029] The present invention also provides an application method of the NiO-Ca9Co 12 O 28 catalytic oxygen carrier, which is used as a catalyst for alcohol reforming to produce hydrogen.

[0030] The present invention studies and finds that using the NiO-Ca9Co 12 O 28 catalytic oxygen carrier as a catalyst for alcohol reforming to produce hydrogen can form a reduced Ni-Co alloy transition state during the catalytic process, so that the activation energy of alcohol reforming to produce hydrogen can be effectively reduced, and better hydrogen production effect can be obtained at a lower temperature. Moreover, it is beneficial to regenerate at a low temperature, and the reforming hydrogen production activity of the regenerated material is basically not lost, and the catalytic stability is excellent.

[0031] In the present invention, the NiO-Ca9Co 12 O 28 oxygen carrier realizes autothermal hydrogen production from ethanol through the bulk transfer of lattice oxygen and surface catalytic oxidation; at the same time, the functional NiO-Ca9Co 12 O 28 catalytic oxygen carrier fission products can be used as a CO2 adsorbent to in-situ adsorb CO2, thereby obtaining high-purity hydrogen;

[0032] In the application of the present invention, the NiO-Ca9Co 12 O 28The oxygen carrier catalyst contacts with alcohol and water to carry out a reforming reaction to produce hydrogen;

[0033] Preferably, the alcohol is an alcohol that is gaseous at 400-650 °C; preferably a C1-C10 mono- or polyol; more preferably at least one of ethanol, propanol, and isopropanol;

[0034] Preferably, the water / alcohol molar ratio has no particular requirement, for example, it can be 3-6, preferably 3-4.

[0035] The reforming reaction of the present invention can be carried out at a relatively low temperature. Preferably, the temperature of the reforming reaction is 400-650 °C, preferably 500-550 °C.

[0036] In a preferred application of the present invention, the solid product formed by the reforming reaction is contacted with an oxygen-containing atmosphere to carry out a regeneration reaction, and carbon dioxide-containing gas and the regenerated NiO-Ca9Co 12 O 28 oxygen carrier catalyst are collected.

[0037] In the present invention, the solid product of the reforming contains in-situ formed Ni-Co alloy and CaO.

[0038] Preferably, the temperature of the regeneration reaction is 700-900 °C, and the preferred range is 750-800 °C. In the present invention, regeneration can be achieved at a relatively low temperature. Moreover, the catalytic stability of the regenerated product is excellent.

[0039] In the present invention, the oxygen-containing atmosphere in the regeneration stage is, for example, pure oxygen or a mixture of oxygen and other gases. The mixture is, for example, at least one of air, oxygen-nitrogen mixture, and oxygen-inert gas mixture.

[0040] The present invention also provides a method for producing hydrogen by lattice oxygen-induced adsorption-enhanced alcohol reforming based on NiO-Ca9Co 12 O 28 oxygen carrier catalyst. The alcohol is subjected to reforming hydrogen production treatment by using the application method described in the present invention;

[0041] Subsequently, the solid product formed by reforming hydrogen production is regenerated by using the application described in the invention to obtain the regenerated NiO-Ca9Co 12 O 28 oxygen carrier catalyst and carbon dioxide gas;

[0042] The reforming hydrogen production treatment and the regeneration treatment are a chemical looping cycle. The chemical looping cycle is repeated, and the hydrogen generated in the reforming hydrogen production stage is collected, and the carbon dioxide generated in the regeneration stage is collected.

[0043] Preferably based on NiO-Ca9Co of the present invention12 O 28 Method for enhancing adsorption-induced hydrogen production from ethanol reforming by lattice oxygen of catalytic oxygen carrier, comprising the following steps:

[0044] 1) Reforming:

[0045] NiO-Ca9Co 12 O 28 react with ethanol and water vapor to carry out reforming hydrogen production reaction;

[0046] Ethanol first undergoes partial oxidation and reacts with NiO-Ca9Co 12 O 28 to generate H2 and CO2. At the same time, NiO-Ca9Co 12 O 28 is reduced to Ni-Co alloy and CaO. CaO in-situ absorbs CO2 to promote the forward movement of the reaction; NiO-Ca9Co 12 O 28 The percentage of Ni in the catalytic oxygen carrier in the total molar amount of Ni, Co and Ca elements is greater than 0% and less than or equal to 20%; preferably 5-15%; the reaction temperature range for reforming hydrogen production reaction is 450-550 °C. The water-to-ethanol ratio range is 3-4.

[0047] 2) The solid products (such as Ni-Co alloy and CaO) generated in the step 1) are subjected to a regeneration reaction in an oxygen-containing atmosphere to obtain regenerated NiO-Ca9Co 12 O 28 solid and by-product CO2; the temperature in the regeneration stage is 700-800 °C;

[0048] 3) Repeat step (1) and step (2) to realize the chemical looping treatment of alcohol.

[0049] In a preferred embodiment of the present invention, in the NiO-Ca9Co 12 O 28 oxygen carrier, the Ca9Co 12 O 28 is arranged in a layered manner, and the NiO is uniformly distributed in the form of nanoparticles on the Ca9Co 12 O 28 substrate. It is found that the lattice oxygen of NiO uniformly supported on the layered Ca9Co 12 O 28 substrate has appropriate ethanol partial oxidation activity, can selectively convert ethanol into CO2 and H2, and realize the ethanol partial oxidation reaction in a short time; at the same time, the NiO-Ca9Co 12 O 28After the oxygen carrier is reduced by ethanol, nickel-cobalt alloy and CaO are produced, and the catalyst is reorganized, thus maintaining the catalyst particle size and inhibiting the sintering and agglomeration of NiO-Ca9Co 12 O 28 During the ethanol reforming reaction stage, the nickel-cobalt alloy can catalyze the reforming of ethanol to produce hydrogen, obtaining hydrogen and by-product CO2. At the same time, CaO can be used as an adsorbent to in-situ adsorb CO2, thus realizing the one-step production of high-purity hydrogen.

[0050] Beneficial effects

[0051] (1): The present invention provides a brand-new NiO-Ca9Co 12 O 28 catalytic oxygen carrier, which has excellent alcohol reforming hydrogen production activity, can obtain better hydrogen production effect at lower temperature. Moreover, it is easy to regenerate, and the regenerated product has excellent catalytic stability; thus, it is beneficial to realize the chemical looping cycle of alcohol reforming hydrogen production.

[0052] For example, taking ethanol reforming as an example, the hydrogen concentration obtained by the existing ethanol steam reforming technology is not high, resulting in high subsequent separation costs. The method of the present invention induces the reduction of the catalytic oxygen carrier through lattice oxygen to generate CaO, which can in-situ adsorb the CO2 produced by the reforming reaction. Based on the LeChatelier principle, the equilibrium of the SRE and water gas shift reaction (WGS: CO→CO2) moves towards the direction of hydrogen production, which is beneficial to enhancing hydrogen selectivity, improving hydrogen atom utilization rate, reducing the concentration of other gases, and then obtaining high-quality hydrogen in one step. The ethanol conversion rate of the existing ethanol steam technology is not high, resulting in low ethanol utilization rate. The method of the present invention enables the basic complete conversion of ethanol through the alloying of metal active phases, effectively improving the ethanol conversion rate and the reforming reaction activity. The existing ethanol steam reforming technology cannot achieve autothermal, resulting in high energy consumption and material deterioration. The method of the present invention provides heat through the exothermic CO2 adsorption reaction and the oxygen carrier oxidation reaction, and transfers the heat to the endothermic reforming reaction and CO2 desorption reaction to achieve autothermal, reducing the reforming and regeneration reaction temperatures and reducing the reaction energy consumption. The existing ethanol steam reforming technology has the problem of catalyst deactivation, resulting in a decline in the adsorption performance of the adsorbent and poor cycle stability. The method of the present invention improves the catalyst deactivation and adsorbent agglomeration phenomena through the separation and reorganization of phases, making the adsorbent generated by the reforming reaction have high stability and maintaining good CO2 adsorption performance. At the same time, the alloying of the active phase improves the catalyst activity. The existing ethanol steam technology uses air and oxygen to achieve the oxidation reaction. The method of the present invention can produce hydrogen through the partial oxidation of fuel by the lattice oxygen of the oxygen carrier (metal oxide), directly supplying oxygen by lattice oxygen, avoiding the direct contact between ethanol and oxygen molecules, and realizing the in-situ separation of air at the same time. Enhancing the experimental safety.

[0053] (2) The NiO-Ca9Co described in the present invention 12 O 28 The oxygen carrier catalyst is easy to prepare and has a low preparation cost. Moreover, it can achieve efficient and highly stable chemical-looping preparation, with excellent performance and cost advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 Based on NiO-Ca9Co 12 O 28 Schematic diagram of the method for hydrogen production by ethanol reforming with enhanced adsorption induced by lattice oxygen of the oxygen carrier catalyst

[0055] Figure 2 Initial phase analysis of the oxygen carrier after calcination with different Ni addition amounts (Examples 1 / 2 and Comparative Examples 1 / 2)

[0056] Figure 3 Initial phase analysis of the oxygen carrier after calcination at different calcination temperatures (Examples 3 and 4)

[0057] Figure 4 Comparison of hydrogen concentration in the ethanol steam reforming reaction of oxygen carrier catalysts with different Ni element contents

[0058] Figure 5 Comparison of hydrogen production rate of oxygen carrier catalysts with different Ni element contents (Examples 1 and Comparative Example 2) in the ethanol steam reforming reaction (hydrogen production rate at 10 min);

[0059] Figure 6 Effect of different temperatures on hydrogen concentration in ethanol steam reforming in Application Example 2

[0060] Figure 7 Thermogravimetric analysis diagram of the reduction and regeneration process of the oxygen carrier catalyst at different regeneration temperatures in a nitrogen-air mixed atmosphere for Application Example 3

[0061] Figure 8 Thermogravimetric analysis diagram of the reduction and regeneration process of the oxygen carrier catalyst at different regeneration temperatures in a pure nitrogen atmosphere for Application Example 3

[0062] Figure 9 SEM and surface scan diagrams of the 10Ni-CCO oxygen carrier catalyst before the reforming reaction and after the reaction for Application Example 3

[0063] Figure 10 SEM and surface scan diagrams of the 10Ni-CCO oxygen carrier catalyst 4 min after the reforming reaction for Application Example 3

[0064] Figure 11 SEM and surface scan diagrams of the 10Ni-CCO oxygen carrier catalyst 10 min after the reforming reaction for Application Example 3

[0065] Figure 12Phase analysis of the 10Ni-CCO oxygen carrier at different cycle numbers for Application Example 4

[0066] Figure 13 Hydrogen concentration graph of the 10Ni-CCO oxygen carrier after 50 cycles for Application Example 4

[0067] Figure 14 Carbon dioxide adsorption kinetics analysis graph of 0Ni-CCO for Application Example 4

[0068] Figure 15 Carbon dioxide adsorption kinetics analysis graph of 10Ni-CCO for Application Example 4

[0069] Figure 16 Ni2p XPS spectrum of 10Ni-CCO before reaction for Application Example 4

[0070] Figure 17 Ni2p XPS spectrum of 10Ni-CCO after reaction for Application Example 4

[0071] Figure 18 Co2p XPS spectra of 0Ni-CCO and 10Ni-CCO before reaction for Application Example 4

[0072] Figure 19 Co2p XPS spectra of 0Ni-CCO and 10Ni-CCO after reaction for Application Example 4 Detailed implementation method

[0073] The present invention will be further described below in conjunction with the accompanying drawings of the specification and embodiments.

[0074] The overall schematic diagram of the method of the present invention is as shown in Figure 1 and is a schematic diagram of a method for hydrogen production by adsorption-enhanced ethanol reforming induced by lattice oxygen of a NiO-Ca9Co 12 O 28 oxygen carrier. The hydrogen production method provided by the present invention comprises the following steps: (1) Ethanol gas is introduced into an ethanol reforming reactor, and ethanol first undergoes partial oxidation and reacts with NiO-Ca9Co 12 O 28 to generate H2 and CO2. At the same time, NiO-Ca9Co 12 O 28 is reduced to a Ni-Co alloy and CaO; (2) The generated Ni-Co alloy catalyzes the steam reforming of ethanol to produce hydrogen, and at the same time, by-product CO2 is obtained, while CaO in-situ adsorbs the generated CO2 and is converted into CaCO3; (3) Air is introduced into the regeneration reactor and heated, and CaCO3 desorbs CO2 and is re-converted into CaO. The air reacts with CaO and the Ni-Co alloy to generate a NiO-Ca9Co 12 O 28 solid.

[0075] In the present invention, the water-alcohol ratio refers to the molar ratio of water to alcohol;

[0076] Example 1

[0077] A NiO-Ca9Co 12 O 28 oxygen carrier was prepared by the citric acid sol-gel method. The specific steps are as follows:

[0078] 6.577 g (0.023 mol) of nickel nitrate, cobalt nitrate and calcium nitrate (wherein Ca / Co is proportioned according to the stoichiometric ratio, and the molar percentage of Ni relative to (Ni + Ca + Co) is 10%) were dissolved in 55 mL of deionized water. The molar ratio of the addition amount of citric acid to the addition amount of cations (total amount of nickel, cobalt, and calcium) was 1.3. The solution was heated to 85 °C and continuously stirred for 3 h to form a polymerized gel, which was placed in a blast drying oven at 150 °C (T1) for 4 h for foaming and aging, and then ground evenly and placed in a muffle furnace for calcination at 800 °C (T2) in an air atmosphere for 4 h. The obtained solid powder was labeled 10Ni-CCO.

[0079] As Figure 2 shown, according to the X-ray diffraction (XRD) results, it can be found that the NiO-Ca9Co 12 O 28 oxygen carrier can obtain stable NiO and Ca9Co 12 O 28 phases respectively after calcination at 800 °C. Through the sol-gel method, Co element and Ca element can form a composite oxide Ca9Co 12 O 28 , and Ni element will not be doped into the lattice of the composite oxide Ca9Co 12 O 28 .

[0080] Example 2

[0081] Compared with Example 1, the difference is only that the molar percentage of Ni relative to (Ni + Ca + Co) is 20%, and other parameters are the same as those in Example 1; the steps are as follows:

[0082] Nickel nitrate, cobalt nitrate 6.577 g (0.023 mol), calcium nitrate (wherein, Ca / Co is formulated according to the stoichiometric ratio, and the molar percentage of Ni relative to (Ni + Ca + Co) is 20%) are dissolved in 55 mL of deionized water. The addition amount of citric acid and the addition amount of cations (total amount of nickel, cobalt, calcium) have a molar ratio of 1.3. The solution is heated to 85 °C and continuously stirred for 3 h to form a polymerized gel, which is placed in a blast drying oven at 150 °C for 4 h for foaming and aging, and then ground evenly and placed in a muffle furnace for calcination at 800 °C in an air atmosphere for 4 h. The obtained solid powder is marked as 20Ni-CCO, and its XRD results are as Figure 2 shown.

[0083] Comparative Example 1

[0084] Compared with Example 1, the difference is only that the molar percentage of Ni relative to (Ni + Ca + Co) is 30%, and other parameters are the same as those in Example 1; the steps are as follows:

[0085] Nickel nitrate, cobalt nitrate 6.577 g (0.023 mol), calcium nitrate (wherein, Ca / Co is formulated according to the stoichiometric ratio, and the molar percentage of Ni relative to (Ni + Ca + Co) is 30%) are dissolved in 55 mL of deionized water. The addition amount of citric acid and the addition amount of cations (total amount of nickel, cobalt, calcium) have a molar ratio of 1.3. The solution is heated to 85 °C and continuously stirred for 3 h to form a polymerized gel, which is placed in a blast drying oven at 150 °C for 4 h for foaming and aging, and then ground evenly and placed in a muffle furnace for calcination at 800 °C in an air atmosphere for 4 h. The obtained solid powder is marked as 30Ni-CCO, and its XRD results are as Figure 2 shown.

[0086] Comparative Example 2

[0087] Compared with Example 1, the difference is only that Ni is not added, and the steps are as follows:

[0088] A Ca9Co 12 O 28 catalytic oxygen carrier is prepared by the citric acid sol-gel method. The specific steps are as follows: Cobalt nitrate 6.577 g (0.023 mol) and calcium nitrate (wherein, Ca / Co is formulated according to the stoichiometric ratio) are dissolved in 55 mL of deionized water. The addition amount of citric acid and the addition amount of cations (total amount of cobalt, calcium) have a molar ratio of 1.3. The solution is heated to 85 °C and continuously stirred for 3 h to form a polymerized gel, which is placed in a blast drying oven at 150 °C for 4 h for foaming and aging, and then ground evenly and placed in a muffle furnace for calcination at 800 °C in an air atmosphere for 4 h. The obtained solid powder is marked as 0Ni-CCO, and its XRD results are as Figure 2 shown.

[0089] Example 3

[0090] Compared with Example 1, the only difference is that the calcination temperature T2 is changed to 750 °C; other parameters are the same as those in Example 1, and the XRD results are as Figure 3 shown.

[0091] Example 4

[0092] Compared with Example 1, the only difference is that the calcination temperature T2 is changed to 900 °C; other parameters are the same as those in Example 1, and the XRD results are as Figure 3 shown. NiO and Ca9Co 12 O 28 phases can be effectively synthesized within the range of 750-900 °C.

[0093] Application Example 1:

[0094] It includes the following steps:

[0095] 1) Use a heating tape to preheat an aqueous solution of ethanol, where the flow rate of the ethanol aqueous solution is 0.005 mL / min and the water-to-alcohol ratio is 3;

[0096] 2) Add 0.3 g of 10Ni-CCO oxygen carrier to a fuel reactor at 550 °C, and introduce a mixture of preheated ethanol and water vapor for 35 min. Under the action of the 10Ni-CCO oxygen carrier, ethanol is converted into H2 and CO2, and at the same time, NiO in the oxygen carrier is reduced to Ni, and Co is reduced to Co and CaO;

[0097] 3) The reduced metallic elements Ni and Co will form a Ni-Co alloy as a catalyst for the ethanol steam reforming reaction, continuously converting the ethanol and water vapor mixture into H2 and CO2, and the CaO reduced in step 2) will act as an adsorbent to in-situ adsorb the CO2 generated during the reaction and finally be converted into CaCO3;

[0098] 4) The oxygen carrier regeneration process is carried out in a regeneration reactor. At 800 °C, introduce a mixture of nitrogen and oxygen with a certain concentration (the oxygen content is 20 vol.%), and control the gas flow rate of the mixture to be 40 mL / min, and the cumulative gas introduction time is 15 min;

[0099] 5) Steps 2)-4) are cycled to realize the cyclic reduction and oxidation of the oxygen carrier, and continuously carry out the adsorption-enhanced ethanol reforming for hydrogen production induced by lattice oxygen.

[0100] Application Example 1-1

[0101] Compared with Application Example 1, the only difference is that an equal weight of 20Ni-CCO oxygen carrier, 30Ni-CCO oxygen carrier or 0Ni-CCO is used to replace the 10Ni-CCO oxygen carrier described above.

[0102] The reaction performances of each example and comparative example are as Figure 4 , 5 shown. The preferred 10Ni-CCO of the present invention has better hydrogen production performance.

[0103] Application Example 2 (Study on the Optimal Temperature for Reforming Hydrogen Production Reaction)

[0104] Compared with Application Example 1, the difference is only that the product 10Ni-CCO prepared in Example 1 is used as the catalyst, and the temperature in the steam reforming and hydrogen production stage (450 - 600 °C) is changed. Other operations are the same as those in Application Example 1. The results are shown in Figure 6 . It is found by fixed-bed experiments that when the reforming reaction temperature is 550 °C, it is the optimal catalytic ethanol steam reforming temperature, and the hydrogen concentration in its product can be as high as about 96%.

[0105] Application Example 3 (Study on the Optimal Temperature for Oxygen Carrier Regeneration)

[0106] It includes the following steps:

[0107] 1) Using the product 10Ni-Co / CaCO3 after the reaction in step 3) of Application Example 1 as a sample, putting it into a quartz crucible and placing it on the balance of a thermogravimetric analyzer (TGA);

[0108] 2) Passing 60 mL / min of pure nitrogen or a 50 vol.% nitrogen-air mixed atmosphere into the TGA, analyzing the CO2 desorption performance at different temperatures (650 - 800 °C) during the oxygen carrier regeneration stage. The results are as Figure 7 , 8 shown. It can be found that both conditions show similar rules. When the regeneration temperature is 800 °C, the mass reduction rate during the CO2 desorption process is the highest. Then 800 °C is the optimal regeneration reaction temperature to ensure the regeneration effect and cycle stability of the oxygen carrier.

[0109] Figures 9 - 11 The TEM-EDS surface scanning images of the 10Ni-CCO oxygen carrier after the reforming reaction at 550 °C (0 min, 4 min, 10 min) are shown. It can be found that only the lattice fringes of surface NiO can be found in the fresh 10Ni-CCO catalytic oxygen carrier, and the distributions of Ni and Co elements are uneven. After the oxygen carrier undergoes the reforming reaction for 4 min, the lattice fringes of the Ni-Co alloy can be found, but the crystal plane spacing is different from the standard value. After the oxygen carrier undergoes the reforming reaction for 10 min, it can be found that in some regions, only the Co and Ni elements are evenly distributed, without Ca element, and the crystal plane spacing of the Ni-Co alloy is in good agreement with the standard value, indicating that the Ni-Co alloy phase is formed during the reforming reaction.

[0110] Application Example 4: Chemical looping reaction

[0111] The chemical looping cycle in step 5) of Example 1 was analyzed. As Figure 12 、 Figure 13 shown, the cyclic stability of the 10Ni-CCO oxygen carrier catalyst was investigated, that is, the activity of the oxygen carrier after multiple redox cycles. It can be seen that the 10Ni-CCO oxygen carrier catalyst has a stable phase after 50 cycles, and the hydrogen concentration is guaranteed to be about 90%. Through the splitting and recombination of the carrier, sintering and agglomeration are greatly inhibited, and quite good cyclic stability performance is maintained, which has obvious advantages compared with conventional nickel-based catalysts.

[0112] The kinetic analysis of the carbon dioxide adsorption rate in the CO2 reforming reaction of 0Ni-CCO and 10Ni-CCO was carried out using a thermogravimetric analyzer. The specific fitting results are shown in Table 1. Among them, k1 and k2 are the exponential constants representing the kinetic control stage and the diffusion control stage. The k1 and k2 values of 10Ni-CCO are both higher than those of 0Ni-CCO, indicating that the addition of NiO can effectively improve the surface chemical adsorption process. Figure 14 、 Figure 15 are the carbon dioxide adsorption kinetic analysis diagrams of the two oxygen carriers. Among them, E represents the reaction activation energy. The larger the activation energy value, the stronger the dependence on the absorption temperature. The activation energy value of surface chemical adsorption of 10Ni-CCO is lower, indicating that the introduction of Ni element can reduce the temperature dependence of CO2 adsorption performance.

[0113] Table 1 Kinetic index parameters of the two oxygen carriers

[0114]

[0115] Figures 16 - 19 are the XPS spectra of 0Ni-CCO and 10Ni-CCO before and after the reaction. The Ni2p spectrum of 10Ni-CCO before the reaction shows obvious NiO characteristic peaks, mainly showing a double-peak structure. The binding energy difference between Ni2p 1 / 2 and Ni2p 3 / 2 is 18.4 eV. After the reaction, the NiO characteristic double-peak structure disappears, and at the same time, the generation of Ni-Co alloy peaks is observed. The Co2p spectra of 0Ni-CCO and 10Ni-CCO before the reaction both show three valence states, which is consistent with the composition of Ca9Co 12 O 28 . After introducing the Ni element, the content of Co 4+ becomes lower while the content of Co 4+ becomes higher, proving that Ni doping can enhance its reducibility. After the reaction, the characteristic peaks of Ni-Co alloy can be detected in both, which is consistent with the results of the Ni2p spectrum.

Claims

1. A method for hydrogen production by adsorption-enhanced alcohol reforming induced by lattice oxygen of a NiO-Ca9Co 12 O 28 catalytic oxygen carrier, characterized in that Using NiO-Ca9Co 12 O 28 as the catalytic oxygen carrier for alcohol reforming to produce hydrogen, contacting with alcohol and water, performing reforming to produce hydrogen treatment, and obtaining hydrogen; the NiO-Ca9Co 12 O 28 catalytic oxygen carrier comprises NiO and Ca9Co 12 O 28 ; Subsequently, the solid product formed by the reforming reaction is contacted with an oxygen-containing atmosphere for a regeneration reaction, and carbon dioxide gas and regenerated NiO-Ca9Co 12 O 28 catalytic oxygen carrier are collected; The reforming hydrogen production process and the regeneration process form a chemical looping cycle. By repeating the chemical looping cycle, hydrogen generated in the reforming hydrogen production stage is collected, and carbon dioxide generated in the regeneration stage is collected. The described NiO-Ca9Co 12 O 28 is obtained by carrying out a sol-gel reaction with a nickel source, a calcium source, a cobalt source, and a complexing carbon source, drying the resulting gel to obtain a precursor, and then subjecting the precursor to a calcination treatment; the complexing carbon source is at least one of citric acid, citrate, and ethylene glycol.

2. The method for hydrogen production by lattice oxygen-induced adsorption-enhanced alcohol reforming based on the NiO-Ca9Co 12 O 28 catalytic oxygen carrier, characterized in that The described Ca9Co 12 O 28 is a lamellar structure material.

3. The method for hydrogen production by adsorption-enhanced alcohol reforming induced by lattice oxygen of the NiO-Ca9Co 12 O 28 catalytic oxygen carrier, characterized in that The described NiO-Ca9Co 12 O 28 In, the percentage of Ni in the total molar amount of Ni, Co, and Ca elements is greater than 0% and less than or equal to 20%.

4. The method for hydrogen production by lattice oxygen-induced adsorption-enhanced alcohol reforming based on the NiO-Ca9Co 12 O 28 catalytic oxygen carrier, characterized in that The described NiO-Ca9Co 12 O 28 In it, the percentage of Ni in the total molar amount of Ni, Co and Ca elements is 5-15%.

5. The method for hydrogen production by adsorption-enhanced alcohol reforming induced by lattice oxygen of the NiO-Ca9Co 12 O 28 catalytic oxygen carrier, characterized in that The nickel source, calcium source, and cobalt source are at least one of water-soluble salts, oxides, and hydroxides of their respective metal elements. Among the nickel source, calcium source, and cobalt source, the percentage of Ni in the total molar amount of Ni, Co, and Ca elements is greater than 0% and less than or equal to 30%. The ratio of the complex carbon source to the total molar amount of Ni, Co, and Ca elements in the raw material is (1 - 1.5):

1. The calcination atmosphere is an oxygen-containing atmosphere. The temperature in the calcination stage is 750 - 900 °C. The calcination time is 2 - 6 h.

6. The method for hydrogen production by lattice oxygen-induced adsorption enhanced alcohol reforming based on the NiO-Ca9Co 12 O 28 catalytic oxygen carrier, characterized in that During the reforming hydrogen production process, the alcohol is an alcohol that is gaseous at 400 - 650 °C.

7. The method for hydrogen production by lattice oxygen-induced adsorption-enhanced alcohol reforming based on the NiO-Ca9Co 12 O 28 catalytic oxygen carrier, characterized in that In the reforming hydrogen production process, the alcohol is a C1-C 10 unit alcohol.

8. The method for hydrogen production by adsorption-enhanced alcohol reforming induced by lattice oxygen of the NiO-Ca9Co 12 O 28 catalytic oxygen carrier, characterized in that During the reforming hydrogen production process, the alcohol is at least one of ethanol, propanol, and isopropanol.

9. The method for hydrogen production by adsorption-enhanced alcohol reforming induced by lattice oxygen of a NiO-Ca9Co 12 O 28 catalytic oxygen carrier, characterized in that During the reforming hydrogen production process, the water / alcohol molar ratio is 3 - 6.

10. The method for hydrogen production by adsorption-enhanced alcohol reforming induced by lattice oxygen of the NiO-Ca9Co 12 O 28 catalytic oxygen carrier, characterized in that During the reforming hydrogen production process, the water / alcohol molar ratio is 3 - 4.

11. The method for hydrogen production by adsorption-enhanced alcohol reforming induced by lattice oxygen of the NiO-Ca9Co 12 O 28 catalytic oxygen carrier, characterized in that The temperature of the reforming hydrogen production reaction is 400 - 650 °C.

12. The method for hydrogen production by lattice oxygen-induced adsorption-enhanced alcohol reforming using the NiO-Ca9Co 12 O 28 catalytic oxygen carrier as claimed in claim 11, characterized in that The temperature of the reforming hydrogen production reaction is 450 - 550 °C.

13. The method for hydrogen production by adsorption-enhanced alcohol reforming induced by lattice oxygen of the NiO-Ca9Co 12 O 28 catalytic oxygen carrier, characterized in that The solid product contains in-situ formed Ni-Co alloy and CaO. The temperature of the regeneration reaction is 700 - 900 °C.

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