CN114660256B - Method for measuring content of copper in each valence state in copper-zinc catalyst - Google Patents

Method for measuring content of copper in each valence state in copper-zinc catalyst Download PDF

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CN114660256B
CN114660256B CN202210351653.9A CN202210351653A CN114660256B CN 114660256 B CN114660256 B CN 114660256B CN 202210351653 A CN202210351653 A CN 202210351653A CN 114660256 B CN114660256 B CN 114660256B
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copper
tpr
tpo
peak area
curve
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CN114660256A (en
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高文桂
冼俊杰
许云添
王宇宁
周嘉斌
陈志远
龚杰松
纳薇
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Kunming University of Science and Technology
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/20Metals
    • G01N33/202Constituents thereof
    • G01N33/2028Metallic constituents
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N31/00Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
    • G01N31/005Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods investigating the presence of an element by oxidation

Abstract

The invention relates to a method for measuring the content of copper in each valence state in a copper-zinc catalyst, belonging to the technical field of measuring the content of active ingredients of the catalyst. According to the difference of oxidation or reduction performances of copper with different valence states, the invention combines temperature programming reduction (H 2 TPR test and temperature programmed oxidation (O) 2 TPO) test to give H as catalyst 2 -TPR curve and O 2 TPO curve, at H due to the different degree of difficulty and variability of reduction or oxidation of copper of different valence 2 -TPR curve, O 2 The peak positions of hydrogen consumption peaks or oxygen consumption peaks corresponding to copper with different valence states on the TPO curve are different, and according to the peak positions and combined with the peak areas of the hydrogen consumption peaks or the oxygen consumption peaks, the hydrogen consumption peaks or the oxygen consumption peaks respectively pass through O 2 TPO in combination with H 2 TPR assay (TPO-TPR) and H 2 -TPR in combination with O 2 TPO assay (TPR-TPO) to give H 2 -TPR and O 2 And (3) carrying out peak integration treatment on the curve of TPO to obtain the corresponding hydrogen consumption peak area and oxygen consumption peak area, and calculating the mole ratio of zero-valent copper, cuprous oxide and cupric oxide in the copper-zinc catalyst and the mole ratio of copper and zinc in the catalyst. The method can conveniently measure the amounts of copper in different valence states and the proportion of copper and zinc in the copper-zinc catalyst.

Description

Method for measuring content of copper in each valence state in copper-zinc catalyst
Technical Field
The invention relates to a method for measuring the content of copper in each valence state in a copper-zinc catalyst, belonging to the technical field of measuring the content of active ingredients of the catalyst.
Background
The copper-based catalyst has better catalytic performance and is widely used in dehydrogenation, hydrogenation and oxidation reactions. In copper-based catalysts, the addition of ZnO can promote the dispersion and reduction of copper and enhance the stability of the catalyst, and the interaction between Cu-ZnO interfaces has an important influence on the activity of the catalyst. Copper zinc catalysts have been used in industry to catalyze synthesis gas to methanol, lower alcohols, water gas shift reactions, and the like. Copper zinc catalysts in CO in recent years 2 Hydrogenation becomes a research hot spot in C1 chemistry constructed by relying on CO 2 The method can reduce CO for synthesizing methanol, dimethyl ether, methane, low-carbon alcohol and the like as raw materials 2 Is significant for realizing carbon neutralization. Along with the deep research work of the copper-zinc catalyst, the catalyst synthesis method is more various, the application field is also continuously expanded, and a great deal of researches show that copper in the copper-zinc catalyst mainly exists in the form of zero-valent metal, +1-valent salt or +2-valent salt or oxide, and the requirements on the existence form of active copper in the catalyst are different for different catalytic reactions, so that the determination of copper in different valence states in the copper-zinc catalyst is particularly important.
At present, the measurement of copper in various valence states in the copper-zinc catalyst is mainly characterized by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy, the precision and the accuracy are reliable, and the ratio of each element or the same element in different valence states of the surface layer can be obtained by comparing the measured combination energy spectrum of each element with a standard energy spectrum and carrying out peak separation treatment calculation. However, XPS is limited by electron escape depth, and the measurement depth is generally only about 2 nm, so that the characteristics of the catalyst surface layer (or surface phase) are mainly measured, and quantitative analysis of the catalyst phase is dwarfed. The surface layer element content of the catalyst is not equivalent to the actual element content in the catalyst due to the surface aggregation effect, and is also expressed as bulk element content. At present, no convenient method is available for quantitatively determining the amounts of copper in different valence states in the copper-zinc catalyst.
Disclosure of Invention
Aiming at the problem of measuring copper with different valence states in the copper-zinc catalyst in the prior art, the invention provides a method for measuring the content of copper with different valence states in the copper-zinc catalyst, namely, according to the difference of oxidation or reduction performances of copper with different valence states, the method is combined with temperature programming reduction (H) 2 TPR test and temperature programmed oxidation (O) 2 TPO) test to give H as catalyst 2 -TPR curve and O 2 TPO curve, at H due to the different degree of difficulty and variability of reduction or oxidation of copper of different valence 2 -TPR curve, O 2 The peak positions of hydrogen consumption peaks or oxygen consumption peaks corresponding to copper with different valence states on the TPO curve are different, and according to the peak positions and combined with the peak areas of the hydrogen consumption peaks or the oxygen consumption peaks, the hydrogen consumption peaks or the oxygen consumption peaks respectively pass through O 2 TPO in combination with H 2 TPR assay (TPO-TPR) and H 2 -TPR in combination with O 2 TPO assay (TPR-TPO) to give H 2 -TPR and O 2 And (3) carrying out peak integration treatment on the curve of TPO to obtain the corresponding hydrogen consumption peak area and oxygen consumption peak area, and calculating the mole ratio of zero-valent copper, cuprous oxide and cupric oxide in the copper-zinc catalyst and the mole ratio of copper and zinc in the catalyst. The method can conveniently measure the amounts of copper in different valence states and the proportion of copper and zinc in the copper-zinc catalyst.
The invention reduces the temperature programmed (H) 2 TPR) and temperature programmed oxidation (O) 2 -TPO) quantitatively calculating the proportion of copper in each valence state in the catalyst according to the difference of oxidation or reduction performances of copper in different valence states and the relation of the hydrogen consumption or the oxygen consumption and the hydrogen consumption peak area or the oxygen consumption peak area in a fixed proportion;
H 2 TPR relates to the formulae (1) and (2), O 2 TPO relates to equations (3) and (4):
CuO+H 2 =Cu+H 2 O (1)
Cu 2 O+H 2 =2Cu+H 2 O (2)
2Cu+O 2 =2CuO (3)
2Cu 2 O+O 2 =4CuO (4)
a method for measuring the content of copper in each valence state in a copper-zinc catalyst comprises the following specific steps:
(1) Dividing the copper-zinc catalyst to be detected into a group A copper-zinc catalyst and a group B copper-zinc catalyst;
(2) Programmed temperature oxidation O by group A copper-zinc catalyst 2 TPO test to give O 2 -TPO curve a; then carrying out programmed temperature reduction H 2 TPR test to give H 2 -TPR curve a;
(3) Group B copper-zinc catalyst for programmed heating reduction H 2 TPR test gives H 2 -TPR curve B; then carrying out programmed temperature oxidation O 2 TPO test to give O 2 -TPO curve B;
(4) Temperature programming reduction H of pure CuO 2 TPR test gives H 2 -TPR curve C;
the temperature programmed oxidation O 2 TPO test and temperature programmed reduction H 2 The TPR test differs only in the type of process gas and in the end temperature of the test, the other process conditions being identical (for example, the start temperature, the rate of temperature change, the flow rate of process gas, the pressure of gas, etc. are all kept identical) to eliminate the effects of the inconsistency of the kinetic parameters; programmed temperature oxidation O 2 Treatment gas for TPO test was O-containing 2 Is used for reducing H by temperature programming 2 The treatment gas tested for TPR was H-containing 2 Is a reducing gas of (2);
(5) Setting the oxygen consumption peak area corresponding to the quantity of Cu simple substance in the catalyst sample as a 1 ,Cu 2 Oxygen consumption peak area corresponding to the amount of O substance is a 2 The method comprises the steps of carrying out a first treatment on the surface of the CuO is first at H 2 Reduction to Cu in TPR 0 Reo (r) 2 CuO is oxidized in TPO, and the corresponding oxygen consumption peak area is a 3
For O 2 The peak area of oxygen consumption peak corresponding to the amount of Cu simple substance obtained by carrying out peak separation and peak area integration treatment on the TPO curve A is a 1 And Cu 2 Oxygen consumption peak area corresponding to the amount of O substance is a 2
For O 2 The peak area integration treatment is carried out on the TPO curve B to obtain the total integrated area a 0 The method comprises the steps of carrying out a first treatment on the surface of the Reduction of H due to zinc oxide at elevated temperature 2 Partially reduced in the TPR test and in O 2 The reduced zinc of this part of the TPO process is oxidized, so a 0 Comprises oxygen consumption peak of the partial zinc oxidation, the zinc oxidation temperature is about 200 ℃, O 2 Integrating the zinc oxidation temperature (about 200 ℃) in the TPO curve B to obtain the oxygen consumption peak area a 4
Calculating the CuO first in H 2 Reduction to Cu in TPR 0 Reo (r) 2 CuO is oxidized in TPO, and the corresponding oxygen consumption peak area is a 3 The method comprises the steps of carrying out a first treatment on the surface of the Then according to the oxygen consumption peak area a 1 The oxygen consumption peak area is a 2 And oxygen consumption peak area a 3 Calculating the molar ratio of zero-valent copper, cuprous oxide and cupric oxide;
(6)H 2 the peak area integration treatment is carried out on the TPR curve A to obtain the total integrated area b of all hydrogen consumption peak fits 0 The method comprises the steps of carrying out a first treatment on the surface of the For H 2 The peak area integration treatment is carried out on the TPR curve C to obtain the hydrogen consumption peak area b of pure CuO 1
In the Cu-Zn catalyst, H 2 The reduction temperature in the TPR process is above 600 ℃, part of zinc oxide is reduced, and the hydrogen consumption peak needs to be corrected, namely H needs to be deducted 2 The hydrogen consumption peak generated by zinc oxide reduction in the TPR curve A is calculated, and the hydrogen consumption peak b 'corresponding to copper in the corrected catalyst sample is calculated' 0
The molar ratio of Cu to Zn in the Cu-Zn catalyst was calculated.
The CuO is first in H 2 Reduction to Cu in TPR 0 Reo (r) 2 CuO oxidation in TPO, corresponding oxygen consumption peak area a 3 The calculation formula of (2) is
a 3 =a 0 -a 1 -2a 2 -a 4
The mole ratio of zero-valent copper, cuprous oxide and cupric oxide is
Cu:Cu 2 O:CuO=a 1 :a 2 :a 3
Wherein a is 1 A is the oxygen consumption peak area corresponding to the quantity of Cu simple substance in the catalyst sample 2 Is Cu 2 Oxygen consumption peak area corresponding to the amount of O substance; a, a 3 First in H for CuO 2 Reduction to Cu in TPR 0 Reo (r) 2 Oxidation in TPOCuO, the corresponding oxygen consumption peak area; a, a 4 Oxygen consumption peak area at zinc oxidation temperature; a, a 0 Is O 2 The TPO curve B is subjected to a peak area integration process to obtain a total integrated area.
Further, the corrected catalyst sample has a hydrogen consumption peak b 'corresponding to copper' 0 The calculation formula of (2) is
The molar ratio of Cu to Zn in the Cu-Zn catalyst is
Cu∶Zn=b′ 0 :(b 1 -b′ 0 )
Wherein a is 0 Is O 2 The peak area integration treatment is carried out on the TPO curve B to obtain the total integrated area, a 4 Is the oxygen consumption peak area, H at the oxidation temperature of zinc 2 The peak area integration treatment is carried out on the TPR curve A to obtain the total integrated area b of all hydrogen consumption peak fits 0 ,b′ 0 B, in order to correct the hydrogen consumption peak corresponding to copper in the catalyst sample 1 Is H 2 And (3) carrying out peak area integration treatment on the TPR curve C to obtain the hydrogen consumption peak area of the pure CuO.
The O contains 2 Is O 2 /N 2 、O 2 Ar or O 2 He; containing H 2 Is H 2 /N 2 、H 2 Ar or H 2 /He。
Preferably, the specific method of the step (2) is that
1) Placing the group A copper-zinc catalyst in a sample tube of a chemical adsorption instrument, and purging the group A copper-zinc catalyst sample in a temperature zone with the temperature lower than 200 ℃ by adopting protective gas;
2) After the purging, the temperature programmed oxidation (O) 2 -TPO) test: introducing O-containing material into a sample tube of a chemisorber 2 The temperature of the A group copper-zinc catalyst sample is programmed at the temperature rising rate of 1-10K/min, a chemical adsorption instrument records signals, and O with the temperature as an abscissa and the signal value of the A group copper-zinc catalyst sample as an ordinate is obtained 2 -TPO curve a;
3) Ending the programmed temperature oxidation (O) 2 -TPO) test followed by temperature programmed reduction H 2 TPR test: introducing protective gas into a sample tube of the chemical adsorption instrument for purging, and switching the treatment gas to contain H when the temperature is reduced to below 50 DEG C 2 The temperature of the sample in the sample tube is programmed at the temperature rising rate of 1-10K/min, the signal is recorded by a chemical adsorption instrument, and the H with the temperature as the abscissa and the signal value of the sample as the ordinate is obtained 2 -TPR curve a;
preferably, the specific method of the step (3) is that
1) Placing the group B copper-zinc catalyst in a sample tube of a chemical adsorption instrument, and purging the group B copper-zinc catalyst sample in a temperature zone with the temperature lower than 200 ℃ by adopting protective gas;
2) After purging, temperature programming reduction H is carried out 2 TPR test-introduction of H-containing into a sample tube of a chemisorber 2 The temperature of the sample of the copper-zinc catalyst of the group B is programmed at the temperature rising rate of 1-10K/min, and a chemical adsorption instrument records signals to obtain H with the temperature as the abscissa and the signal value of the sample of the copper-zinc catalyst of the group B as the ordinate 2 -TPR curve B;
3) Ending the programmed temperature reduction H 2 After the TPR test, a temperature programmed oxidation (O) 2 -TPO) test: introducing protective gas into a sample tube of the chemical adsorption instrument for purging, and switching the treatment gas to be O-containing when the temperature is reduced to below 50 DEG C 2 The temperature of the sample in the sample tube is programmed at the temperature rising rate of 1-10K/min, and the signal is recorded by a chemical adsorption instrument to obtain O with the temperature as the abscissa and the signal value of the sample as the ordinate 2 -TPO curve B;
preferably, the specific method of the step (4) is that
1) Placing pure CuO in a sample tube of a chemical adsorption instrument, and purging a pure CuO catalyst sample in a temperature zone with a temperature lower than 200 ℃ by adopting protective gas;
2) After purging, temperature programming reduction H is carried out 2 TPR test-introduction of H-containing into a sample tube of a chemisorber 2 Is a reducing gas of (2)The temperature of a pure CuO catalyst sample is programmed at the temperature rising rate of 1-10K/min, a chemical adsorption instrument records signals, and H with the temperature as an abscissa and the signal value of the pure CuO catalyst sample as an ordinate is obtained 2 -TPR curve C.
The protective gas is N 2 Ar or He.
The beneficial effects of the invention are as follows:
(1) According to the difference of oxidation or reduction performances of copper with different valence states, the invention utilizes the temperature programming reduction/oxidation to measure the proportion of copper with different valence states in the copper-zinc catalyst, namely the combination of the temperature programming reduction (H) 2 TPR test and temperature programmed oxidation (O) 2 TPO) test to give H as catalyst 2 -TPR curve and O 2 TPO curve, for H 2 -TPR curve and O 2 Performing peak separation and peak integration treatment on the TPO curve to obtain corresponding hydrogen consumption peak area and oxygen consumption peak area, and conveniently calculating the mole ratio of zero-valent copper, cuprous oxide and cupric oxide in the copper-zinc catalyst and the mole ratio of copper and zinc in the catalyst;
(2) The method can conveniently and accurately measure the amounts of copper in different valence states and the proportion of copper and zinc in the copper-zinc catalyst.
Drawings
FIG. 1 is O of example 1 2 -TPO curve a;
FIG. 2 is H of example 1 2 -TPR curve a;
FIG. 3 is H of example 1 2 -TPR curve B;
FIG. 4 is O of example 1 2 -TPO curve B;
FIG. 5 is H of examples 1 and 2 2 -TPR curve C;
FIG. 6 is O of example 2 2 -TPO curve a;
FIG. 7 is a diagram of example 2H 2 -TPR curve a;
FIG. 8 is H of example 2 2 -TPR curve B;
FIG. 9 is O of example 2 2 TPO curve B.
Detailed Description
The invention will be described in further detail with reference to specific embodiments, but the scope of the invention is not limited to the description.
Example 1:
copper zinc catalyst a for preparing polyvalent copper: copper acetylacetonate and zinc acetylacetonate are used as precursors, after being prepared into aqueous solution, the aqueous solution is put into a hydrothermal reaction kettle, the aqueous reaction kettle reacts for 24 hours at the temperature of 180 ℃ to prepare a copper-zinc catalyst, wherein Cu is Zn=5:4 (molar ratio), the generated solid product is filtered, washed by deionized water and dried to obtain the copper-zinc catalyst A;
a method for measuring the content of copper in each valence state in a copper-zinc catalyst comprises the following specific steps:
(1) The copper-zinc catalyst A to be tested is divided into a copper-zinc catalyst A group (30 mg) and a copper-zinc catalyst B group (30 mg);
(2) Programmed temperature oxidation O by group A copper-zinc catalyst 2 TPO test to give O 2 -TPO curve a; then carrying out programmed temperature reduction H 2 TPR test to give H 2 -TPR curve a;
the specific method comprises the following steps of
1) Placing 30mg of the A-group copper-zinc catalyst in a sample tube of a chemical adsorption instrument, introducing protective gas He, heating to 50 ℃ at 10 ℃/min, and purging the A-group copper-zinc catalyst sample for 60min;
2) After the purging, the temperature programmed oxidation (O) 2 -TPO) test: introducing O-containing material into a sample tube of a chemisorber 2 Is an oxidizing gas (4%O) 2 -96% He), programming the temperature of the A group copper-zinc catalyst sample to 800 ℃ at a temperature rising rate of 10K/min, and recording signals by a chemical adsorption instrument to obtain O with the temperature as an abscissa and the signal value of the A group copper-zinc catalyst sample as an ordinate 2 -TPO curve a (see fig. 1);
3) Ending the programmed temperature oxidation (O) 2 -TPO) test followed by temperature programmed reduction H 2 TPR test: introducing protective gas He into a sample tube of the chemical adsorption instrument to purge for 60min and cooling to below 50 ℃, and switching the treatment gas to contain H 2 Reducing gas (10% H) 2 -90% Ar), the temperature of the sample in the sample tube is programmed to 1000 ℃ at a temperature rising rate of 10K/min, and the signal is recorded by a chemical adsorption instrumentObtaining H with temperature as abscissa and sample signal value as ordinate 2 -TPR curve a (see fig. 2);
the gas flow rate is 20mL/min in the test process, and other parameter settings are consistent except for different atmospheres;
(3) Group B copper-zinc catalyst for programmed heating reduction H 2 TPR test gives H 2 -TPR curve B; then carrying out programmed temperature oxidation O 2 TPO test to give O 2 -TPO curve B;
the specific method comprises the following steps of
1) Placing 30mg of the group B copper-zinc catalyst in a sample tube of a chemical adsorption instrument, introducing protective gas He, heating to 50 ℃ at 10 ℃/min, and purging a group B copper-zinc catalyst sample for 60min;
2) After purging, temperature programming reduction H is carried out 2 TPR test-introduction of H-containing into a sample tube of a chemisorber 2 Reducing gas (10% H) 2 -90% Ar), programming the temperature of the group B copper-zinc catalyst sample to 1000 ℃ at a temperature rising rate of 10K/min, and recording signals by a chemical adsorption instrument to obtain H with the temperature as an abscissa and the signal value of the group B copper-zinc catalyst sample as an ordinate 2 -TPR curve B (see fig. 3);
3) Ending the programmed temperature reduction H 2 After the TPR test, a temperature programmed oxidation (O) 2 -TPO) test: introducing protective gas He into a sample tube of the chemical adsorption instrument for purging for 60min, and switching the treatment gas to O-containing gas when the temperature is reduced to below 50 DEG C 2 Is an oxidizing gas (4%O) 2 -96% He), programming the temperature of the sample in the sample tube to 800 ℃ at a temperature rising rate of 10K/min, and recording signals by a chemical adsorption instrument to obtain O with the temperature as an abscissa and the signal value of the sample as an ordinate 2 -TPO curve B (see fig. 4);
(4) Temperature programming reduction H of pure CuO 2 TPR test gives H 2 -TPR curve C;
the specific method comprises the following steps of
1) Placing 30mg of pure CuO in a sample tube of a chemical adsorption instrument, introducing protective gas He, heating to 50 ℃ at 10 ℃/min, and purging a pure CuO catalyst sample for 60min;
2) After purging, temperature programming reduction H is carried out 2 TPR test-introduction of H-containing into a sample tube of a chemisorber 2 Reducing gas (10% H) 2 -90% Ar), programming the pure CuO catalyst sample to 1000 ℃ at a temperature rising rate of 10K/min, and recording signals by a chemical adsorption instrument to obtain H with the temperature as an abscissa and the signal value of the pure CuO catalyst sample as an ordinate 2 -TPR curve C (see fig. 5);
the temperature programmed oxidation O 2 TPO test and temperature programmed reduction H 2 The TPR test differs only in the type of process gas and in the end temperature of the test, the other process conditions being identical (for example, the start temperature, the rate of temperature change, the flow rate of process gas, the pressure of gas, etc. are all kept identical) to eliminate the effects of the inconsistency of the kinetic parameters; programmed temperature oxidation O 2 Treatment gas for TPO test was O-containing 2 Is used for reducing H by temperature programming 2 The treatment gas tested for TPR was H-containing 2 Is a reducing gas of (2);
(5) Setting the oxygen consumption peak area corresponding to the quantity of Cu simple substance in the catalyst sample as a 1 ,Cu 2 Oxygen consumption peak area corresponding to the amount of O substance is a 2 The method comprises the steps of carrying out a first treatment on the surface of the CuO is first at H 2 Reduction to Cu in TPR 0 Reo (r) 2 CuO is oxidized in TPO, and the corresponding oxygen consumption peak area is a 3
For O 2 The peak area of oxygen consumption peak corresponding to the amount of Cu simple substance obtained by carrying out peak separation and peak area integration treatment on the TPO curve A is a 1 And Cu 2 Oxygen consumption peak area corresponding to the amount of O substance is a 2
For O 2 The peak area integration treatment is carried out on the TPO curve B to obtain the total integrated area a 0 The method comprises the steps of carrying out a first treatment on the surface of the Reduction of H due to zinc oxide at elevated temperature 2 Partially reduced in the TPR test and in O 2 The reduced zinc of this part of the TPO process is oxidized, so a 0 Comprises oxygen consumption peak of the partial zinc oxidation, the zinc oxidation temperature is about 200 ℃, O 2 Integrating the zinc oxidation temperature (about 200 ℃) in the TPO curve B to obtain the oxygen consumption peak area a 4
CalculatingCuO is first at H 2 Reduction to Cu in TPR 0 Reo (r) 2 CuO is oxidized in TPO, and the corresponding oxygen consumption peak area is a 3 The method comprises the steps of carrying out a first treatment on the surface of the CuO is first at H 2 Reduction to Cu in TPR 0 Reo (r) 2 CuO oxidation in TPO, corresponding oxygen consumption peak area a 3 The calculation formula of (2) is
a 3 =a 0 -a 1 -2a 2 -a 4
Then according to the oxygen consumption peak area a 1 The oxygen consumption peak area is a 2 And oxygen consumption peak area a 3 Calculating the molar ratio of zero-valent copper, cuprous oxide and cupric oxide;
the mole ratio of zero-valent copper, cuprous oxide and cupric oxide is
Cu:Cu 2 O:CuO=a 1 :a 2 :a 3
Wherein a is 1 A is the oxygen consumption peak area corresponding to the quantity of Cu simple substance in the catalyst sample 2 Is Cu 2 Oxygen consumption peak area corresponding to the amount of O substance; a, a 3 First in H for CuO 2 Reduction to Cu in TPR 0 Reo (r) 2 -CuO oxidation in TPO, corresponding oxygen consumption peak area; a, a 4 Oxygen consumption peak area at zinc oxidation temperature; a, a 0 Is O 2 Performing peak area integration treatment on the TPO curve B to obtain a total integrated area;
(6)H 2 the peak area integration treatment is carried out on the TPR curve A to obtain the total integrated area b of all hydrogen consumption peak fits 0 The method comprises the steps of carrying out a first treatment on the surface of the For H 2 The peak area integration treatment is carried out on the TPR curve C to obtain the hydrogen consumption peak area b of pure CuO 1
In the Cu-Zn catalyst, H 2 The reduction temperature in the TPR process is above 600 ℃, part of zinc oxide is reduced, and the hydrogen consumption peak needs to be corrected, namely H needs to be deducted 2 The hydrogen consumption peak generated by zinc oxide reduction in the TPR curve A is calculated, and the hydrogen consumption peak b 'corresponding to copper in the corrected catalyst sample is calculated' 0 The method comprises the steps of carrying out a first treatment on the surface of the Corrected hydrogen consumption peak b 'corresponding to copper in catalyst sample' 0 The calculation formula of (2) is
Calculating the mole ratio of Cu to Zn in the Cu-Zn catalyst, wherein the mole ratio of Cu to Zn in the Cu-Zn catalyst is
Cu∶Zn=b′ 0 :(b 1 -b′ 0 )
A in the present embodiment 1 =72.57,a 2 =297.44,a 0 =1129.59,b 0 =17755.77,b 1 =31877.62,a 4 =15.83, calculate
Cu:Cu 2 O:CuO=8.721:35.744:55.536
Cu:Zn=0.5492:0.4508
The measurement result of the plasma emission spectrometer (ICP-AES) is Cu: zn=0.5479:0.4521, and the measurement result is basically consistent with the measurement result.
Example 2:
copper zinc catalyst B for preparing polyvalent copper: preparing an aqueous solution by taking copper acetylacetonate and zinc acetylacetonate as precursors, then placing the aqueous solution into a hydrothermal reaction kettle, reacting for 24 hours at 180 ℃ in the hydrothermal reaction kettle to prepare a copper-zinc catalyst, wherein Cu is Zn=4:5 (molar ratio), filtering the generated solid product, washing the solid product with deionized water, and drying to obtain a copper-zinc catalyst B;
a method for measuring the content of copper in each valence state in a copper-zinc catalyst comprises the following specific steps:
(1) The copper-zinc catalyst A to be tested is divided into a copper-zinc catalyst A group (50 mg) and a copper-zinc catalyst B group (50 mg);
(2) Programmed temperature oxidation O by group A copper-zinc catalyst 2 TPO test to give O 2 -TPO curve a; then carrying out programmed temperature reduction H 2 TPR test to give H 2 -TPR curve a;
the specific method comprises the following steps of
1) Placing 50mg of the A-group copper-zinc catalyst in a sample tube of a chemical adsorption instrument, introducing protective gas Ar, heating to 50 ℃ at 10 ℃/min, and purging the A-group copper-zinc catalyst sample for 60min;
2) After the purging, the temperature programmed oxidation (O) 2 -TPO) test: introducing the sample tube containing the chemical adsorption instrumentO 2 Is an oxidizing gas (4%O) 2 -96% Ar), programming the temperature of the A group copper-zinc catalyst sample to 800 ℃ at a temperature rising rate of 10K/min, and recording signals by a chemical adsorption instrument to obtain O with the temperature as an abscissa and the signal value of the A group copper-zinc catalyst sample as an ordinate 2 -TPO curve a (see fig. 6);
3) Ending the programmed temperature oxidation (O) 2 -TPO) test followed by temperature programmed reduction H 2 TPR test: introducing protective gas Ar into a sample tube of the chemical adsorption instrument to purge for 60min, and switching the treatment gas to contain H when the temperature is reduced to below 50 DEG C 2 Reducing gas (10% H) 2 -90% Ar), programming the temperature of the sample in the sample tube to 1000 ℃ at a temperature rising rate of 10K/min, and recording signals by a chemical adsorption instrument to obtain H with the temperature as an abscissa and the signal value of the sample as an ordinate 2 -TPR curve a (see fig. 7);
the gas flow rate is 20mL/min in the test process, and other parameter settings are consistent except for different atmospheres;
(3) Group B copper-zinc catalyst for programmed heating reduction H 2 TPR test gives H 2 -TPR curve B; then carrying out programmed temperature oxidation O 2 TPO test to give O 2 -TPO curve B;
the specific method comprises the following steps of
1) Placing 50mg of the group B copper-zinc catalyst in a sample tube of a chemical adsorption instrument, introducing protective gas Ar, heating to 50 ℃ at 10 ℃/min, and purging a group B copper-zinc catalyst sample for 60min;
2) After purging, temperature programming reduction H is carried out 2 TPR test-introduction of H-containing into a sample tube of a chemisorber 2 Reducing gas (10% H) 2 -90% Ar), programming the temperature of the group B copper-zinc catalyst sample to 1000 ℃ at a temperature rising rate of 10K/min, and recording signals by a chemical adsorption instrument to obtain H with the temperature as an abscissa and the signal value of the group B copper-zinc catalyst sample as an ordinate 2 -TPR curve B (see fig. 8);
3) Ending the programmed temperature reduction H 2 After the TPR test, a temperature programmed oxidation (O) 2 -TPO) test: introducing a shielding gas into a sample tube of a chemical adsorption instrumentPurging Ar for 60min, cooling to below 50deg.C, and switching the treatment gas to O-containing gas 2 Is an oxidizing gas (4%O) 2 -96% Ar), heating the sample in the sample tube to 800 ℃ at a heating rate of 10K/min, and recording signals by a chemical adsorption instrument to obtain O with the temperature as an abscissa and the signal value of the sample as an ordinate 2 -TPO curve B (see fig. 9);
(4) Temperature programming reduction H of pure CuO 2 TPR test gives H 2 -TPR curve C;
the specific method comprises the following steps of
1) Placing 50mg of pure CuO in a sample tube of a chemical adsorption instrument, introducing protective gas Ar, heating to 50 ℃ at 10 ℃/min, and purging a pure CuO catalyst sample for 60min;
2) After purging, temperature programming reduction H is carried out 2 TPR test-introduction of H-containing into a sample tube of a chemisorber 2 Reducing gas (10% H) 2 -90% Ar), programming the pure CuO catalyst sample to 1000 ℃ at a temperature rising rate of 10K/min, and recording signals by a chemical adsorption instrument to obtain H with the temperature as an abscissa and the signal value of the pure CuO catalyst sample as an ordinate 2 -TPR curve C (see fig. 5);
the temperature programmed oxidation O 2 TPO test and temperature programmed reduction H 2 The TPR test differs only in the type of process gas and in the end temperature of the test, the other process conditions being identical (for example, the start temperature, the rate of temperature change, the flow rate of process gas, the pressure of gas, etc. are all kept identical) to eliminate the effects of the inconsistency of the kinetic parameters; programmed temperature oxidation O 2 Treatment gas for TPO test was O-containing 2 Is used for reducing H by temperature programming 2 The treatment gas tested for TPR was H-containing 2 Is a reducing gas of (2);
(5) Setting the oxygen consumption peak area corresponding to the quantity of Cu simple substance in the catalyst sample as a 1 ,Cu 2 Oxygen consumption peak area corresponding to the amount of O substance is a 2 The method comprises the steps of carrying out a first treatment on the surface of the CuO is first at H 2 Reduction to Cu in TPR 0 Reo (r) 2 CuO is oxidized in TPO, and the corresponding oxygen consumption peak area is a 3
For O 2 TPO starterThe line A is subjected to peak separation and peak area integration treatment to obtain the oxygen consumption peak area a corresponding to the quantity of the Cu simple substance 1 And Cu 2 Oxygen consumption peak area corresponding to the amount of O substance is a 2
For O 2 The peak area integration treatment is carried out on the TPO curve B to obtain the total integrated area a 0 The method comprises the steps of carrying out a first treatment on the surface of the Reduction of H due to zinc oxide at elevated temperature 2 Partially reduced in the TPR test and in O 2 The reduced zinc of this part of the TPO process is oxidized, so a 0 Comprises oxygen consumption peak of the partial zinc oxidation, the zinc oxidation temperature is about 200 ℃, O 2 Integrating the zinc oxidation temperature (about 200 ℃) in the TPO curve B to obtain the oxygen consumption peak area a 4
Calculating the CuO first in H 2 Reduction to Cu in TPR 0 Reo (r) 2 CuO is oxidized in TPO, and the corresponding oxygen consumption peak area is a 3 The method comprises the steps of carrying out a first treatment on the surface of the CuO is first at H 2 Reduction to Cu in TPR 0 Reo (r) 2 CuO oxidation in TPO, corresponding oxygen consumption peak area a 3 The calculation formula of (2) is
a 3 =a 0 -a 1 -2a 2 -a 4
Then according to the oxygen consumption peak area a 1 The oxygen consumption peak area is a 2 And oxygen consumption peak area a 3 Calculating the molar ratio of zero-valent copper, cuprous oxide and cupric oxide;
the mole ratio of zero-valent copper, cuprous oxide and cupric oxide is
Cu:Cu 2 O:CuO=a 1 :a 2 :a 3
Wherein a is 1 A is the oxygen consumption peak area corresponding to the quantity of Cu simple substance in the catalyst sample 2 Is Cu 2 Oxygen consumption peak area corresponding to the amount of O substance; a, a 3 First in H for CuO 2 Reduction to Cu in TPR 0 Reo (r) 2 -CuO oxidation in TPO, corresponding oxygen consumption peak area; a, a 4 Oxygen consumption peak area at zinc oxidation temperature; a, a 0 Is O 2 Performing peak area integration treatment on the TPO curve B to obtain a total integrated area;
(6)H 2 the peak area integration treatment is carried out on the TPR curve A to obtainTotal integrated area b fitted to all hydrogen consumption peaks 0 The method comprises the steps of carrying out a first treatment on the surface of the For H 2 The peak area integration treatment is carried out on the TPR curve C to obtain the hydrogen consumption peak area b of pure CuO 1
In the Cu-Zn catalyst, H 2 The reduction temperature in the TPR process is above 600 ℃, part of zinc oxide is reduced, and the hydrogen consumption peak needs to be corrected, namely H needs to be deducted 2 The hydrogen consumption peak generated by zinc oxide reduction in the TPR curve A is calculated, and the hydrogen consumption peak b 'corresponding to copper in the corrected catalyst sample is calculated' 0 The method comprises the steps of carrying out a first treatment on the surface of the Corrected hydrogen consumption peak b 'corresponding to copper in catalyst sample' 0 The calculation formula of (2) is
Calculating the mole ratio of Cu to Zn in the Cu-Zn catalyst, wherein the mole ratio of Cu to Zn in the Cu-Zn catalyst is
Cu∶Zn=b′ 0 :(b 1 -b′ 0 )
A in the present embodiment 1 =223.52,a 2 =45.49,a 0 =780.43,b 0 =14787.41,b 1 =31877.62,a 4 =16.62, calculate
Cu:Cu 2 O:CuO=30.413:6.190:63.397
Cu:Zn=0.4540:0.5460
The measurement result of the plasma emission spectrometer (ICP-AES) is Cu: zn=0.4403:0.5597, and the measurement result is basically consistent with the measurement result.
While the specific embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various changes may be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.

Claims (4)

1. The method for measuring the content of copper in each valence state in the copper-zinc catalyst is characterized by comprising the following specific steps:
(1) Dividing the copper-zinc catalyst to be detected into a group A copper-zinc catalyst and a group B copper-zinc catalyst;
(2) Programmed temperature oxidation O by group A copper-zinc catalyst 2 TPO test to give O 2 -TPO curve a; then carrying out programmed temperature reduction H 2 TPR test to give H 2 -TPR curve a;
(3) Group B copper-zinc catalyst for programmed heating reduction H 2 TPR test gives H 2 -TPR curve B; then carrying out programmed temperature oxidation O 2 TPO test to give O 2 -TPO curve B;
(4) Temperature programming reduction H of pure CuO 2 TPR test gives H 2 -TPR curve C;
the temperature programmed oxidation O 2 TPO test and temperature programmed reduction H 2 In the TPR test, only the type of treatment gas and the end temperature of the test are different, other process conditions are the same, and the temperature programming oxidation O 2 Treatment gas for TPO test was O-containing 2 Is used for reducing H by temperature programming 2 The treatment gas tested for TPR was H-containing 2 Is a reducing gas of (2);
(5) Setting the oxygen consumption peak area corresponding to the quantity of Cu simple substance in the catalyst sample as a 1 ,Cu 2 Oxygen consumption peak area corresponding to the amount of O substance is a 2 The method comprises the steps of carrying out a first treatment on the surface of the CuO is first at H 2 Reduction to Cu in TPR 0 Reo (r) 2 CuO is oxidized in TPO, and the corresponding oxygen consumption peak area is a 3
For O 2 The peak area integration treatment is carried out on the TPO curve A to obtain the oxygen consumption peak area a corresponding to the quantity of the Cu simple substance 1 And Cu 2 Oxygen consumption peak area corresponding to the amount of O substance is a 2
For O 2 The peak area integration treatment is carried out on the TPO curve B to obtain the total integrated area a 0 And oxygen consumption peak area a at zinc oxidation temperature 4
Calculating the CuO first in H 2 Reduction to Cu in TPR 0 Reo (r) 2 CuO is oxidized in TPO, and the corresponding oxygen consumption peak area is a 3 The method comprises the steps of carrying out a first treatment on the surface of the Then according to the oxygen consumption peak area a 1 The oxygen consumption peak area is a 2 And oxygen consumption peak area a 3 Calculating the molar ratio of zero-valent copper, cuprous oxide and cupric oxide;
(6)H 2 the peak area integration treatment is carried out on the TPR curve A to obtain the total integrated area b of all hydrogen consumption peak fits 0 The method comprises the steps of carrying out a first treatment on the surface of the For H 2 The peak area integration treatment is carried out on the TPR curve C to obtain the hydrogen consumption peak area b of pure CuO 1
Calculating a hydrogen consumption peak b 'corresponding to copper in the corrected catalyst sample' 0 I.e. deducting H 2 -hydrogen consumption peaks from zinc oxide reduction in TPR curve a;
the molar ratio of Cu to Zn in the Cu-Zn catalyst was calculated.
2. The method for measuring the copper content of each valence state in the copper-zinc catalyst according to claim 1, wherein the method comprises the following steps: cuO is first at H 2 Reduction to Cu in TPR 0 Reo (r) 2 CuO oxidation in TPO, corresponding oxygen consumption peak area a 3 The calculation formula of (2) is
a 3 =a 0 -a 1 -2a 2 -a 4
The mole ratio of zero-valent copper, cuprous oxide and cupric oxide is
Cu:Cu 2 O:CuO=a 1 :a 2 :a 3
Wherein a is 1 A is the oxygen consumption peak area corresponding to the quantity of Cu simple substance in the catalyst sample 2 Is Cu 2 Oxygen consumption peak area corresponding to the amount of O substance; a, a 3 First in H for CuO 2 Reduction to Cu in TPR 0 Reo (r) 2 -CuO oxidation in TPO, corresponding oxygen consumption peak area; a, a 4 Oxygen consumption peak area at zinc oxidation temperature; a, a 0 Is O 2 The TPO curve B is subjected to a peak area integration process to obtain a total integrated area.
3. The method for measuring the copper content of each valence state in the copper-zinc catalyst according to claim 2, wherein the method comprises the following steps: corrected hydrogen consumption peak b 'corresponding to copper in catalyst sample' 0 The calculation formula of (2) is
The molar ratio of Cu to Zn in the Cu-Zn catalyst is
Cu∶Zn=b′ 0 :(b 1 -b′ 0 )
Wherein a is 0 Is O 2 The peak area integration treatment is carried out on the TPO curve B to obtain the total integrated area, a 4 Is the oxygen consumption peak area, H at the oxidation temperature of zinc 2 The peak area integration treatment is carried out on the TPR curve A to obtain the total integrated area b of all hydrogen consumption peak fits 0 ,b′ 0 B, in order to correct the hydrogen consumption peak corresponding to copper in the catalyst sample 1 Is H 2 And (3) carrying out peak area integration treatment on the TPR curve C to obtain the hydrogen consumption peak area of the pure CuO.
4. The method for measuring the copper content of each valence state in the copper-zinc catalyst according to claim 1, wherein the method comprises the following steps: containing O 2 Is O 2 /N 2 、O 2 Ar or O 2 He; containing H 2 Is H 2 /N 2 、H 2 Ar or H 2 /He。
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