Disclosure of Invention
The invention aims to provide a nickel-hydrocalumite-based derivative catalyst, and the non-noble metal nickel-hydrocalumite-based derivative catalyst is mainly used for the reforming reaction of ethanol steam. The nickel-hydrocalumite-based derivative catalyst obtained after calcination has better activity and thermal stability, is a promising catalyst for reforming ethanol steam, and meanwhile, the use of non-noble metal nickel also has a promoting effect on the actual industrial conversion of the hydrogen production technology by reforming ethanol steam.
According to the hydrocalumite-based derivative catalyst provided by the invention, nickel is introduced into the catalyst by a coprecipitation method, the mass content of the nickel is controlled to be 5-15%, and the molar ratio of calcium ions to aluminum ions in the catalyst is 1-3.
The preparation method of the hydrocalumite-based derivative catalyst provided by the invention comprises the following steps:
(1) preparing a sodium hydroxide solution with the molar volume concentration of 1-2 mol/L;
(2) mixing nitrates corresponding to nickel, aluminum and calcium with deionized water, wherein the volume dosage of the deionized water is 10-12 times of the total mass of the prepared catalyst, and the dosages of the nickel nitrate, the aluminum nitrate and the calcium nitrate are as follows: the mass content of nickel is controlled to be 5-15%, and the molar ratio of calcium ions to aluminum ions in the catalyst is 1-3;
(3) and (3) synchronously dripping the solutions in the step (1) and the step (2) into a sodium carbonate solution in a dripping mode to form a suspension. Controlling the pH value of the suspension liquid to be 11-12, and controlling the temperature of the suspension liquid to be 40-80 ℃;
(4) after the dropwise addition is finished, continuously stirring for 2 hours, and standing the suspension in an oven at 80 ℃ for 10-14 hours;
(5) and (3) filtering the suspension liquid obtained in the step (4) by using deionized water, standing the filtrate in an oven at 80 ℃ for 12 hours, and finally calcining the filtrate at 300-650 ℃ for 4-5 hours to obtain the hydrocalumite-based derivative catalyst for reforming the ethanol steam.
The hydrocalumite-based derivative catalyst prepared by the invention is used for the reforming reaction of ethanol steam, and comprises the following components: the mixed solution of ethanol and water is used as feed liquid used in the reforming reaction of ethanol steam, and the feed liquid is vaporized; placing the hydrocalumite-based derivative catalyst prepared according to claim 1 in a reactor, wherein the reaction temperature is 400-800 ℃, and the reaction formula is as follows:
C2H5OH+3H2O→3CO2+6H2。
the nickel-hydrocalumite-based derivative catalyst, the preparation method and the application thereof provided by the invention have the advantages that:
according to the nickel-hydrocalumite-based derivative catalyst, non-noble metal nickel is used as a main active component during preparation, and the hydrocalumite-based derivative catalyst prepared by a coprecipitation method is matched, so that the cost of the catalyst is reduced, and meanwhile, better catalytic activity and thermal stability can be guaranteed. The nickel-hydrocalumite-based derivative catalyst is used for the ethanol steam reforming reaction, has good activity and thermal stability, has good catalytic activity in the ethanol steam reforming hydrogen production reaction, and almost completely converts ethanol; at a proper reaction temperature, the yield of hydrogen can reach 85%.
Detailed Description
According to the hydrocalumite-based derivative catalyst (Ni-CaAl-LDHs) provided by the invention, nickel is introduced into the catalyst by a coprecipitation method, the mass content of the nickel is controlled to be 5-15%, and the molar ratio of calcium ions to aluminum ions in the catalyst is 2.
The preparation method of the hydrocalumite-based derivative catalyst provided by the invention comprises the following steps:
(1) preparing a sodium hydroxide solution with the molar volume concentration of 1-2 mol/L;
(2) mixing nitrates corresponding to nickel, aluminum and calcium with deionized water, wherein the volume dosage (ml) of the deionized water is 10-12 times of the total mass of the catalyst to be prepared, and the dosages of the nickel nitrate, the aluminum nitrate and the calcium nitrate are as follows: the mass content of nickel is controlled to be 5-15% according to the total mass of the catalytic system required to be prepared, and the molar ratio of calcium ions to aluminum ions in the catalyst is 2;
(3) and (3) synchronously dripping the solutions in the step (1) and the step (2) into a sodium carbonate solution in a dripping mode to form a suspension. Controlling the pH value of the suspension liquid to be 11-12, and controlling the temperature of the suspension liquid to be 50-80 ℃;
(4) after the dropwise addition is finished, continuously stirring for 2 hours, and standing the suspension in an oven at 80 ℃ for 10-14 hours;
(5) and (3) filtering the suspension liquid obtained in the step (4) by using deionized water, standing the filtrate in an oven at 80 ℃ for 12 hours, and finally calcining the filtrate at 300-650 ℃ for 4-5 hours to obtain the hydrocalumite-based derivative catalyst for reforming the ethanol steam.
The invention provides a hydrocalumite-based derivative catalyst for an ethanol steam reforming reaction, which comprises the following components in percentage by weight: the mixed solution of ethanol and water is used as feed liquid used in the reforming reaction of ethanol steam, and the feed liquid is vaporized; placing the hydrocalumite-based derivative catalyst prepared by the method in claim 1 in a reactor, wherein the reaction temperature is 700-550 ℃, and the reaction formula is as follows:
C2H5OH+3H2O→3CO2+6H2。
the nickel-hydrocalumite derived catalyst for reforming the ethanol steam has the best catalytic effect when the mass ratio of nickel is 15 percent. Taking a mixed solution of ethanol and water as a feed solution used in the ethanol steam reforming reaction, wherein the feed solution needs to be vaporized before the reaction; the prepared hydrocalumite-based derivative catalyst is placed in a fixed linear reactor, and the usage amount of the catalyst is calculated according to the selected volume space velocity (GHSV) and the volume density of the catalyst. The reaction was carried out at 400-800 ℃.
The following describes embodiments of the method of the invention:
example 1
Preparation of hydrocalumite-based derivative catalyst with nickel content of 5% (5 Ni-CaAl):
the preparation process comprises the following steps:
(1) preparing 1.5mol/L sodium hydroxide solution;
(2) mixing nitrate corresponding to nickel, aluminum and calcium with deionized water. The mass content of nickel in the catalyst is controlled to be 5%, the molar ratio of calcium ions to aluminum ions is 2, namely if 10g of catalyst is prepared, the mass of nitrates corresponding to nickel, aluminum and calcium is about 2.4g, 13g and 17g respectively;
(3) and (3) slowly dripping the solutions in the step (1) and the step (2) into a sodium carbonate solution at the same time to form a suspension. Controlling the pH value to be 11-12 and controlling the suspension liquid to be 50-80 ℃;
(4) after the dripping process is finished, continuously stirring for 2 hours, and standing the suspension in an oven at 80 ℃ for 12 hours;
(5) taking out the suspension, filtering the suspension by using deionized water, continuously standing the suspension in an oven at the temperature of 80 ℃ for 12 hours, and calcining the catalyst at the temperature of 500 ℃ for 5 hours;
(6) as shown in FIG. 1, the diffraction peaks of the prepared 5Ni-CaAl catalyst have characteristic diffraction peaks corresponding to those of the hydrocalumite, indicating that the structure of the hydrocalumite is formed.
And (3) testing conditions are as follows: 0.7ml of 5Ni-CaAl prepared in example 1 was taken and placed in the middle of the reactor. The test was carried out at a molar ratio of ethanol to water of 1: 6. The catalyst is pre-reduced for 1 hour at 900 ℃ before reaction test, and then the reaction test is carried out in situ, wherein the reaction temperature is respectively 700 ℃,650 ℃,600 ℃ and 550 ℃. The activity evaluation of the catalyst is expressed in terms of ethanol conversion and hydrogen yield:
wherein n isi,inAnd ni,outRespectively representing the concentration of each substance at the inlet and outlet, and the concentration is measured by calibration of a gas chromatograph (FULI GC 9790). The results of the ethanol conversion and hydrogen yield calculations are shown in table 1.
Example 2
A hydrocalumite-based derivative catalyst (10Ni-CaAl) having a nickel content of 10% was prepared.
The preparation process comprises the following steps:
(1) preparing 2mol/L sodium hydroxide solution;
(2) mixing nitrate corresponding to nickel, aluminum and calcium with deionized water. The mass content of nickel in the catalyst is controlled to be 10%, and the molar ratio of calcium ions to aluminum ions in the catalyst is controlled to be 2, namely if 10g of catalyst is prepared, the mass of nitrates corresponding to nickel, aluminum and calcium is respectively about 5g, 12g and 15 g;
(3) and (3) slowly dripping the solutions in the step (1) and the step (2) into a sodium carbonate solution at the same time to form a suspension. Controlling the pH to be 11-12 and controlling the suspension to be about 50-80 ℃;
(4) after the dripping process is finished, continuously stirring for 2 hours, and standing the suspension in an oven at 80 ℃ for 12 hours;
(5) taking out the suspension, filtering the suspension by using deionized water, continuing to stand in an oven at 80 ℃ for 12 hours, and calcining the catalyst at 500-550 ℃ for 4-5 hours;
(6) as shown in FIG. 2, the diffraction peaks of the prepared 10Ni-CaAl catalyst existed corresponding to the characteristic diffraction peaks of hydrocalumite, indicating that a layered structure of hydrocalumite was formed.
And (3) testing conditions are as follows: 0.7ml of 10Ni-CaAl prepared in example 2 was taken and placed in the middle of the reactor. The test was carried out at a molar ratio of ethanol to water of 1: 6. The catalyst is pre-reduced for 1 hour at 900 ℃ before reaction test, and then the reaction test is carried out in situ, wherein the reaction temperature is respectively 700 ℃,650 ℃,600 ℃ and 550 ℃. The ethanol conversion and hydrogen yield were calculated in the same manner as in example 1, and the calculation results are shown in Table 1.
Example 3
A hydrocalumite-based derivative catalyst (15Ni-CaAl) having a nickel content of 15% was prepared.
The preparation process comprises the following steps:
(1) preparing 1mol/L sodium hydroxide solution;
(2) mixing nitrate corresponding to nickel, aluminum and calcium with deionized water. The mass content of nickel in the catalyst is controlled to be 15%, and the molar ratio of calcium ions to aluminum ions in the catalyst is controlled to be 2, namely if 10g of catalyst is prepared, the mass of nitrates corresponding to nickel, aluminum and calcium is respectively about 7.4g, 10g and 13 g;
(3) slowly dripping the solutions obtained in the step 1) and the step 2) into a sodium carbonate solution at the same time to form a suspension. Controlling the pH to be 11-12 and controlling the suspension to be about 50-80 ℃;
(4) after the dripping process is finished, continuously stirring for 2 hours, and standing the suspension in an oven at 80 ℃ for 12 hours;
(5) taking out the suspension, filtering the suspension by using deionized water, continuing to stand in an oven at 80 ℃ for 12 hours, and calcining the catalyst at 500-550 ℃ for 4-5 hours;
(6) as shown in FIG. 3, the diffraction peaks of the prepared 15Ni-CaAl catalyst are present corresponding to the characteristic diffraction peaks of hydrocalumite, indicating that a layered structure of hydrocalumite is formed.
And (3) testing conditions are as follows: 0.7ml of 15Ni-CaAl prepared in example 3 was weighed and placed in the middle of the reactor. The test was carried out at a molar ratio of ethanol to water of 1: 6. The catalyst is pre-reduced for 1 hour at 900 ℃ before reaction test, and then the reaction test is carried out in situ, wherein the reaction temperature is respectively 700 ℃,650 ℃,600 ℃ and 550 ℃. The ethanol conversion and hydrogen yield were calculated as in example 1, and the results are shown in Table 1.
TABLE 1 catalytic Effect of catalyst examples 1-3
The active ingredients in the preparation method of the present invention can be changed or modified in many ways by those skilled in the art, and all changes, substitutions and improvements made on the design and architecture of the present invention are included in the scope of protection of the present invention.