Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a composite oxygen carrier for chemical looping hydrogen production and a preparation method and application thereof. The oxygen carrier is simple to synthesize, and has high porosity and dispersity and excellent hydrogen production performance.
A method for preparing an oxygen carrier for chemical looping hydrogen production, the method comprising the steps of:
(1) mixing an organic ligand and a solvent, wherein the organic ligand comprises one or more of a carboxyl ligand, a ligand containing hetero nitrogen, a carboxylic acid nitrogen-containing mixed ligand, a phosphoric acid ligand, a sulfonic acid ligand and a porphyrin ligand; the solvent comprises one or more of alcohols, ketones, amides, aromatic hydrocarbons, chlorinated hydrocarbons and low-carbon hydrocarbons, and preferably one or more of ethanol, acetone and N, N-dimethylformamide;
(2) and (2) adding a Fe source, a Ti source and a Mn source into the material obtained in the step (1) for reaction, and drying and roasting the reacted material to obtain the oxygen carrier for chemical looping hydrogen production.
In the method, the organic ligands in the step (1) are terephthalic acid and trimesic acid, and the molar ratio of the terephthalic acid to the trimesic acid is (1-9): 1, preferably (2-7): 1, more preferably (3-6): 1.
in the method, the solvent in the step (1) is N, N-dimethylformamide and ethanol, and the molar ratio of the N, N-dimethylformamide to the ethanol is (1-100): 1: preferably (5-80): 1, and more preferably (10-60): 1.
in the above method, the Fe source in step (2) includes at least one of an oxide, a hydroxide, an inorganic acid salt, an organic acid salt, and a chloride of Fe, and also includes hydrates of these compounds, in which water-soluble inorganic acid salts and chlorides of Fe are preferred, and nitrates and chlorides of Fe are more preferred.
In the above method, the Ti source in step (2) includes at least one of an oxide, a hydroxide, an inorganic acid salt, an organic acid salt, and an organic metal compound of Ti, and also includes a hydrate of these compounds, among which a chloride and a titanium alkoxide of Ti are preferable, and a titanium alkoxide is more preferable.
In the above method, the Mn source in step (2) includes at least one of an oxide, a hydroxide, an inorganic acid salt, and an organic acid salt of Mn, and also includes a hydrate of these compounds, in which a water-soluble inorganic acid salt of Mn is preferable, and a nitrate of Mn is more preferable.
In the method, the mass ratio of the Fe source, the Ti source and the Mn source in the step (2) calculated by Fe, Ti and Mn element oxides is (1-9) to (1-5) to 1, preferably (3-7) to (2-4) to 1.
In the method, the Fe source, the Ti source and the Mn source in the step (2) are added into the material in the step (1) sequentially or simultaneously for reaction.
In the above process, the reaction in the step (2) is preferably carried out under stirring.
In the above method, the reaction conditions of the Fe source, the Ti source, and the Mn source during the reaction are generally: total metals: total organic ligand: the molar ratio of the total solvent is 1: 0.2-10: 100-.
In the above method, the oxygen carrier may be formed into a suitable particle form, such as a strip, a sheet, a column, a sphere, a zigzag, etc., according to the techniques known in the art, if necessary. For example, the chemical ring hydrogen-producing oxygen carrier is mixed with a binder (preferably pseudo-boehmite) and kneaded to form the required product.
In the above method, the drying may be performed according to a method known in the art, and examples thereof include a spray drying method, a vacuum drying method, a hot oven drying method, and the like. The drying conditions include, for example, a drying temperature of 60 to 150 ℃, preferably 100 ℃ to 120 ℃, and a drying time of 4 to 48 hours, preferably 6 to 36 hours, and more preferably 8 to 24 hours.
In the method, the dried material is completely converted into the chemical ring hydrogen production oxygen carrier through roasting. Examples of the conditions for the calcination include a calcination temperature of 400-1300 ℃, preferably 600-1200 ℃, more preferably 700-1000 ℃, and a calcination time of 3-10 hours, preferably 4-8 hours. The calcination may be carried out in an oxygen-containing atmosphere (such as air), as required.
The chemical ring hydrogen production oxygen carrier prepared by the method has the weight content of ferric oxide of 30-90%, preferably 40-80% and further preferably 50-75% based on the weight of the oxygen carrier; the weight content of titanium oxide is 40 to 80%, preferably 30 to 60%, and more preferably 20 to 40%; the content of manganese oxide is 1 to 20% by weight, preferably 3 to 15% by weight, and more preferably 5 to 10% by weight.
The oxygen carrier is applied by adopting a fixed bed reactor, taking methane, CO or synthetic gas as raw materials, controlling the reaction temperature to be 500-1200 ℃, the reaction pressure to be 0.1-5 Mpa and the airspeed to be 50-1000 h-1(ii) a Reacting with an oxygen carrier in a reactor to generate a reduction reaction; switching N when feedstock conversion drops significantly2Purging is carried out; introducing water vapor to perform steam reaction with the reduced oxygen carrier, and condensing the product gas to obtain H2(ii) a Switching N2Purging is carried out; and introducing air to fully oxidize the oxygen carrier to complete a cycle reaction.
In the application of the oxygen carrier, the flow rate of the raw material gas is 100-500 ml/min, and the reaction time is 0.2-2 h.
In the application of the oxygen carrier, the distilled water has the water inflow of 0.1-1.0 ml/min, is vaporized into steam through the vaporizing chamber, and has the reaction time of 0.2-2 h.
Compared with the traditional oxygen carrier, the composite oxygen carrier provided by the invention has the advantages of higher porosity, better dispersion and higher reaction efficiency.
Detailed Description
A preparation method of an oxygen carrier for chemical ring hydrogen production comprises the following steps: adding a certain amount of terephthalic acid and trimesic acid into the mixed solution of N, N-dimethylformamide and ethanol for dissolving,then FeCl is added3Stirring and dissolving tetrabutyl titanate and manganese nitrate continuously; transferring the mixed solution into a polytetrafluoroethylene reaction kettle, and putting the reaction kettle into a thermostat for reaction for a period of time at a certain temperature; and taking out the reactant, repeatedly washing with absolute ethyl alcohol, centrifuging and drying to obtain the multielement composite metal organic framework material, and roasting to obtain the target oxygen carrier.
The preparation method has the reaction temperature of 80-200 ℃, preferably 100-180 ℃, the reaction time of 4-72 hours, preferably 12-24 hours, and the rotation speed of 100-400 r/min.
In the above preparation method, the drying temperature is 60-150 ℃, preferably 100-120 ℃, and the drying time is 4-48 hours, preferably 6-36 hours, and more preferably 8-24 hours.
In the preparation method, the roasting condition is that the roasting temperature is 400-1300 ℃, preferably 600-1200 ℃, and more preferably 700-1000 ℃ in the air atmosphere; the roasting time is 1h-24h, preferably 4h-8 h.
In the method of the invention, the calculation formula of the methane conversion rate is as follows:
the calculation formula of the hydrogen production is as follows:
wherein F
N2As a carrier gas N
2Flow rate of S
N2As a carrier gas N
2Peak area of, S
H2Is H
2Peak area of (d), m
OCIs the oxygen carrier mass.
Example 1
Weighing raw materials according to the molar ratio of total metal, organic ligand and solvent of 1: 4.8: 625, wherein the molar ratio of terephthalic acid to trimesic acid is 7: 1, the solvent is a mixture of N, N-dimethylformamide and ethanol, the mass fraction of the ethanol in the total solvent is 28%, the mass ratio of Fe source, Ti source and Mn source calculated by Fe, Ti and Mn element oxides is 6.2: 2.8: 1, and the Fe source is FeCl3The Ti source is titanium isopropoxide, and the Mn source is manganese nitrate.
Firstly, evenly mixing N, N-dimethylformamide and ethanol, then sequentially adding terephthalic acid and trimesic acid, stirring to dissolve, and then sequentially adding FeCl3Continuously stirring and dissolving titanium isopropoxide and manganese nitrate, transferring the mixed solution into a reaction kettle lined with polytetrafluoroethylene after complete dissolution, and reacting for 18.5 hours at 162 ℃ under a sealed condition; and after the reaction is finished, obtaining the multi-element composite metal organic framework material, taking out the reactant, repeatedly washing the reactant by using absolute ethyl alcohol, centrifuging the reactant, drying the reactant for 16 hours at the temperature of 110 ℃, and finally roasting the reactant for 6 hours at the temperature of 900 ℃ to obtain the target oxygen carrier.
The chemical ring hydrogen production reaction is carried out on a fixed bed reactor, methane is used as a raw material, the reaction temperature is 800 ℃, the reaction pressure is 0.1Mpa, and the airspeed is 800h-1(ii) a Reacting with an oxygen carrier in a reactor to generate a reduction reaction; switching N when feedstock conversion drops significantly2Purging is carried out; introducing water vapor to perform steam reaction with the reduced oxygen carrier, and condensing the product gas to obtain H2Analysis by gas chromatography; switching N2Purging is carried out; and introducing air to fully oxidize the oxygen carrier. The conversion rate of methane reaches 99.8 percent, and the single hydrogen yield is 65 ml/g.
Example 2
Weighing raw materials according to the molar ratio of total metal, organic ligand and solvent of 1: 3: 700, wherein the molar ratio of terephthalic acid to trimesic acid is 7: 1, the solvent is a mixture of N, N-dimethylformamide and ethanol, the mass fraction of the ethanol in the total solvent is 28%, the mass ratio of Fe source, Ti source and Mn source in terms of Fe, Ti and Mn element oxides is 6.2: 2.8: 1, and the Fe source is FeCl3The Ti source is titanium isopropoxide, and the Mn source is manganese nitrate.
Firstly, evenly mixing N, N-dimethylformamide and ethanol, then sequentially adding terephthalic acid and trimesic acid, stirring to dissolve, and then sequentially adding FeCl3Continuously stirring and dissolving titanium isopropoxide and manganese nitrate, transferring the mixed solution into a reaction kettle lined with polytetrafluoroethylene after complete dissolution, and reacting for 18.5 hours at 130 ℃ under a closed condition; reaction ofAnd (3) obtaining the multi-element composite metal organic framework material after the reaction is finished, taking out the reactant, repeatedly washing the reactant by using absolute ethyl alcohol, centrifuging the reactant, drying the reactant for 16h at the temperature of 110 ℃, and finally roasting the reactant for 6h at the temperature of 800 ℃ to obtain the target oxygen carrier.
The chemical ring hydrogen production reaction is carried out on a fixed bed reactor, methane is used as a raw material, the reaction temperature is 700 ℃, the reaction pressure is 0.1Mpa, and the airspeed is 800h-1(ii) a Reacting with an oxygen carrier in a reactor to generate a reduction reaction; switching N when feedstock conversion drops significantly2Purging is carried out; introducing water vapor to perform steam reaction with the reduced oxygen carrier, and condensing the product gas to obtain H2Analysis by gas chromatography; switching N2Purging is carried out; and introducing air to fully oxidize the oxygen carrier. The conversion rate of methane reaches 99.8 percent, and the single hydrogen yield is 77 ml/g.
Example 3
Weighing raw materials according to the molar ratio of total metal, organic ligand and solvent of 1: 4.2: 730, wherein the molar ratio of terephthalic acid to trimesic acid is 6.5: 1, the solvent is a mixture of N, N-dimethylformamide and ethanol, the mass fraction of the ethanol in the total solvent is 28%, the mass ratio of Fe source, Ti source and Mn source in terms of Fe, Ti and Mn element oxides is 5.8: 1.8: 1, and the Fe source is FeCl3The Ti source is tetrabutyl titanate, and the Mn source is manganese nitrate.
Firstly, evenly mixing N, N-dimethylformamide and ethanol, then sequentially adding terephthalic acid and trimesic acid, stirring to dissolve, and then sequentially adding FeCl3Stirring and dissolving tetrabutyl titanate and manganese nitrate continuously, transferring the mixed solution into a reaction kettle lined with polytetrafluoroethylene after the mixed solution is completely dissolved, and reacting for 24 hours at 120 ℃ under a closed condition; and after the reaction is finished, obtaining the multi-element composite metal organic framework material, taking out the reactant, repeatedly washing the reactant by using absolute ethyl alcohol, centrifuging the reactant, drying the reactant for 16 hours at the temperature of 110 ℃, and finally roasting the reactant for 6 hours at the temperature of 500 ℃ to obtain the target oxygen carrier.
The chemical ring hydrogen production reaction is carried out on a fixed bed reactor, CO is used as a raw material, the reaction temperature is 500 ℃, the reaction pressure is 0.12Mpa, and the space velocity is 1000h-1(ii) a Reacting with oxygen carrier in reactor to generate reduction reaction(ii) a Switching N when feedstock conversion drops significantly2Purging is carried out; introducing water vapor to carry out steam reaction with the reduced oxygen carrier, and condensing the product gas to obtain H2Analysis by gas chromatography; switching N2Purging is carried out; and introducing air to fully oxidize the oxygen carrier. The CO conversion rate reaches 99.8 percent, and the single hydrogen yield is 88 ml/g.
Example 4
Weighing raw materials according to the molar ratio of total metal to organic ligand to solvent of 1: 5.4: 680, wherein the molar ratio of terephthalic acid to trimesic acid is 5: 1, the solvent is a mixture of N, N-dimethylformamide and ethanol, the mass fraction of the ethanol in the total solvent is 30%, the mass ratio of Fe source, Ti source and Mn source counted by Fe, Ti and Mn element oxides is 5.8: 1.9: 1, the Fe source is ferric nitrate, the Ti source is titanium isopropoxide, and the Mn source is manganese nitrate.
Uniformly mixing N, N-dimethylformamide and ethanol, sequentially adding terephthalic acid and trimesic acid, stirring for dissolving, sequentially adding ferric nitrate, titanium isopropoxide and manganese nitrate, continuously stirring for dissolving, transferring the mixed solution into a reaction kettle lined with polytetrafluoroethylene after complete dissolution, and reacting for 24 hours at 120 ℃ under a closed condition; and after the reaction is finished, obtaining the multi-element composite metal organic framework material, taking out the reactant, repeatedly washing the reactant by using absolute ethyl alcohol, centrifuging the reactant, drying the reactant for 24 hours at the temperature of 110 ℃, and finally roasting the reactant for 6 hours at the temperature of 550 ℃ to obtain the target oxygen carrier.
The chemical ring hydrogen production reaction is carried out on a fixed bed reactor, CO is used as a raw material, the reaction temperature is 550 ℃, the reaction pressure is 0.1Mpa, and the space velocity is 1200h-1(ii) a Reacting with an oxygen carrier in a reactor to generate a reduction reaction; switching N when feedstock conversion drops significantly2Purging is carried out; introducing water vapor to perform steam reaction with the reduced oxygen carrier, and condensing the product gas to obtain H2Analysis by gas chromatography; switching N2Purging is carried out; and introducing air to fully oxidize the oxygen carrier. The CO conversion rate reaches 99.9 percent, and the single hydrogen yield is 84 ml/g.
Example 5
According to the molar ratio of total metal, organic ligand and solventWeighing raw materials according to the ratio of 1: 3.8: 750, wherein the molar ratio of terephthalic acid to trimesic acid is 6.6: 1, the solvent is a mixture of N, N-dimethylformamide and ethanol, the mass fraction of the ethanol in the total solvent is 32%, the mass ratio of Fe source, Ti source and Mn source in terms of Fe, Ti and Mn element oxides is 7.2: 1.6: 1, and the Fe source is FeCl3The Ti source is titanium isopropoxide, the Mn source is MnCl2。
Firstly, evenly mixing N, N-dimethylformamide and ethanol, then sequentially adding terephthalic acid and trimesic acid, stirring to dissolve, and then sequentially adding FeCl3Titanium isopropoxide, MnCl2Continuously stirring and dissolving, after the mixed solution is completely dissolved, transferring the mixed solution into a reaction kettle lined with polytetrafluoroethylene, and reacting for 24 hours at 125 ℃ under a closed condition; and after the reaction is finished, obtaining the multi-element composite metal organic framework material, taking out the reactant, repeatedly washing the reactant by using absolute ethyl alcohol, centrifuging the reactant, drying the reactant for 16 hours at the temperature of 110 ℃, and finally roasting the reactant for 4 hours at the temperature of 600 ℃ to obtain the target oxygen carrier.
The chemical ring hydrogen production reaction is carried out on a fixed bed reactor, CO is used as a raw material, the reaction temperature is 600 ℃, the reaction pressure is 0.3Mpa, and the space velocity is 2000h-1(ii) a Reacting with an oxygen carrier in a reactor to generate a reduction reaction; switching N when feedstock conversion drops significantly2Purging is carried out; introducing water vapor to perform steam reaction with the reduced oxygen carrier, and condensing the product gas to obtain H2Analysis by gas chromatography; switching N2Purging is carried out; and introducing air to fully oxidize the oxygen carrier. The CO conversion rate reaches 99.8 percent, and the single hydrogen yield is 60 ml/g.
Example 6
Weighing raw materials according to the molar ratio of total metal, organic ligand and solvent of 1: 4.3: 650, wherein the molar ratio of terephthalic acid to trimesic acid is 4.2: 1, the solvent is a mixture of N, N-dimethylformamide and ethanol, the mass fraction of the ethanol in the total solvent is 20%, the mass ratio of Fe source, Ti source and Mn source in terms of Fe, Ti and Mn element oxides is 6.5: 2.2: 1, and the Fe source is FeCl3The Ti source is tetrabutyl titanate, and the Mn source is manganese nitrate.
Firstly, N-dimethyl methylAmide and ethanol are mixed evenly, then terephthalic acid and trimesic acid are added in sequence and stirred to be dissolved, and FeCl is added in sequence3Stirring and dissolving tetrabutyl titanate and manganese nitrate continuously, transferring the mixed solution into a reaction kettle lined with polytetrafluoroethylene after the mixed solution is completely dissolved, and reacting for 24 hours at 125 ℃ under a closed condition; and after the reaction is finished, obtaining the multi-element composite metal organic framework material, taking out the reactant, repeatedly washing the reactant by using absolute ethyl alcohol, centrifuging the reactant, drying the reactant for 16 hours at the temperature of 110 ℃, and finally roasting the reactant for 4 hours at the temperature of 550 ℃ to obtain the target oxygen carrier.
The chemical ring hydrogen production reaction is carried out on a fixed bed reactor, synthesis gas is used as a raw material, the reaction temperature is 550 ℃, the reaction pressure is 0.1Mpa, and the space velocity is 2200h-1(ii) a Reacting with an oxygen carrier in a reactor to generate a reduction reaction; switching N when feedstock conversion drops significantly2Purging is carried out; introducing water vapor to perform steam reaction with the reduced oxygen carrier, and condensing the product gas to obtain H2Analysis by gas chromatography; switching N2Purging is carried out; and introducing air to fully oxidize the oxygen carrier. The CO conversion rate reaches 99.9 percent, and the single hydrogen yield is 70 ml/g.
Example 7
Weighing raw materials according to the molar ratio of total metal to organic ligand to solvent of 1: 3.9: 680, wherein the molar ratio of terephthalic acid to trimesic acid is 5.8: 1, the solvent is a mixture of N, N-dimethylformamide and ethanol, the mass fraction of the ethanol in the total solvent is 25%, the mass ratio of Fe source, Ti source and Mn source counted by Fe, Ti and Mn element oxides is 5.5: 1.2: 1, and the Fe source is FeCl3The Ti source is tetrabutyl titanate, and the Mn source is manganese nitrate.
Firstly, evenly mixing N, N-dimethylformamide and ethanol, then sequentially adding terephthalic acid and trimesic acid, stirring to dissolve, and then sequentially adding FeCl3Stirring and dissolving tetrabutyl titanate and manganese nitrate continuously, transferring the mixed solution into a reaction kettle lined with polytetrafluoroethylene after the mixed solution is completely dissolved, and reacting for 24 hours at 125 ℃ under a closed condition; obtaining the multi-element composite metal organic framework material after the reaction is finished, taking out the reactant, repeatedly washing the reactant by absolute ethyl alcohol,centrifuging, drying at 110 ℃ for 16h, and finally roasting at 600 ℃ for 6h to obtain the target oxygen carrier.
The chemical ring hydrogen production reaction is carried out on a fixed bed reactor, synthesis gas is used as a raw material, the reaction temperature is 600 ℃, the reaction pressure is 0.1Mpa, and the space velocity is 2200h-1(ii) a Reacting with an oxygen carrier in a reactor to generate a reduction reaction; switching N when feedstock conversion drops significantly2Purging is carried out; introducing water vapor to perform steam reaction with the reduced oxygen carrier, and condensing the product gas to obtain H2Analysis by gas chromatography; switching N2Purging is carried out; and introducing air to fully oxidize the oxygen carrier. The CO conversion rate reaches 99.9 percent, and the single hydrogen production is 100 ml/g.
Example 8
Weighing raw materials according to the molar ratio of total metal, organic ligand and solvent of 1: 5.1: 710, wherein the molar ratio of terephthalic acid to trimesic acid is 7.3: 1, the solvent is a mixture of N, N-dimethylformamide and ethanol, the mass fraction of the ethanol in the total solvent is 32%, the mass ratio of Fe source, Ti source and Mn source in terms of Fe, Ti and Mn element oxides is 6.5: 1.8: 1, and the Fe source is FeCl3The Ti source is tetrabutyl titanate, and the Mn source is manganese nitrate.
Firstly, evenly mixing N, N-dimethylformamide and ethanol, then sequentially adding terephthalic acid and trimesic acid, stirring to dissolve, and then sequentially adding FeCl3Stirring and dissolving tetrabutyl titanate and manganese nitrate continuously, transferring the mixed solution into a reaction kettle lined with polytetrafluoroethylene after the mixed solution is completely dissolved, and reacting for 24 hours at 125 ℃ under a closed condition; and after the reaction is finished, obtaining the multi-element composite metal organic framework material, taking out the reactant, repeatedly washing the reactant by using absolute ethyl alcohol, centrifuging the reactant, drying the reactant for 16 hours at the temperature of 110 ℃, and finally roasting the reactant for 4 hours at the temperature of 700 ℃ to obtain the target oxygen carrier.
The chemical ring hydrogen production reaction is carried out on a fixed bed reactor, methane is used as a raw material, the reaction temperature is 700 ℃, the reaction pressure is 0.1Mpa, and the space velocity is 2400h-1(ii) a Reacting with an oxygen carrier in a reactor to generate a reduction reaction; switching N when feedstock conversion drops significantly2Purging is carried out; introducing water vapor and reducing carrierCarrying out steam reaction on the oxygen, and condensing the product gas to obtain H2Analysis by gas chromatography; switching N2Purging is carried out; and introducing air to fully oxidize the oxygen carrier. The conversion rate of methane reaches 99.9 percent, and the single hydrogen yield is 77 ml/g.