HG/T 2781-1996 Determination of cobalt and molybdenum content in sulfur-tolerant carbon monoxide shift catalyst
Some standard content:
HG/T2781—1996
This standard is the main active component analysis method standard for the carbon monoxide sulfur-resistant shift catalyst series product standard. This standard adopts the nitroso-R-loaded spectrophotometric method to determine cobalt oxide and the cyanate spectrophotometric method to determine tantalum trioxide. These two methods have been widely used in enterprise standards. This standard formulation mainly studies and tests the influencing factors in the method. And improves and unifies the determination method.
This standard is proposed by the Technical Supervision Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the fertilizer catalyst standardization technical unit of the Ministry of Chemical Industry. This standard is drafted by the Research Institute of Nanjing Chemical Industry (Group) Corporation. The main drafters of this standard are Gu Junzhi and Pan Hongyue. This standard was issued in the first autumn of January 23, 1996. 19
1 Scope
Chemical Industry Standard of the People's Republic of China
Determination of cobalt content in sulfur-resistant carbon monoxide shift catalyst
HG/ T 2781 1996
This standard specifies and 301, B301Q, B Determination method of molybdenum trioxide and molybdenum oxide in 302Q, B303Q and other series carbon monoxide sulfur-resistant shift catalysts.
This standard is applicable to the determination of components of carbon monoxide sulfur-resistant shift catalysts with cobalt oxide and molybdenum trioxide as active components. 2 Reference standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised. All parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T602-88 Preparation of standard solutions for determination of impurities in chemical reagents (ne9ISO 6353/1:1982) GB/T603-88 Preparation of preparations and products used in chemical reagent test methods (neg ISO6353/1:1982) GB/T6682-92 Specifications and test methods for water used in analytical laboratories (eqv ISO3696:1987) 3 Basic requirements for reagents and materials
Unless otherwise specified, the reagents and water used in this standard refer to analytical pure reagents and grade 3 water specified in GB/T6682. Unless otherwise specified, the impurity standard solutions, preparations and products required in the test are prepared in accordance with the provisions of GB/T602 and GB/T603.
Among the listed reagents and materials, if the specific solvent is not specified, it refers to the aqueous solution 4 Preparation of test samples
Mix the laboratory samples evenly, take about 40g by quartering method, and grind them all in a porcelain mortar until the maximum particle size is less than 1mm. Then take about 20g with a quartering agent, continue to grind until it passes through a 150m standard sieve (in accordance with GB/T6003R40/3 series), and place it in a weighing bottle. Dry the sample in an oven at 105-110℃ for 2h, take it out and place it in a hand dryer. Cool to room temperature and set aside. 5 Preparation of test solution
Weigh 0.1g of sample (accurate to 0.0001g), place it in a 250mL beaker, moisten it with a small amount of water, add 10mL (1+t) sulfuric acid solution, cover it with surface blood, and slowly heat (keep it slightly boiling) until it is completely dissolved. Cool, blow water to wash the surface blood and the wall of the cup, transfer this solution to a 100mL volumetric flask, dilute it to the scale with water, and mix well. Dry filter when used. 6 Determination of the content of cobalt oxide Nitrosyl-R salt spectrophotometric method 6.1 Method summary
In a sodium acetate medium with a pH of 5.5 to 6.0, under heating conditions, cobalt (II) reacts with nitrosyl R salt to form a stable soluble red complex. The absorbance is measured at a wavelength of 530 mm to determine the content of cobalt oxide. Approved by the Ministry of Chemical Industry of the People's Republic of China on January 23, 1996, and implemented on January 1, 1997
HG/T 2781 -- 1996
The colored complex formed by iron and the color developer interferes with the determination, which can be eliminated by adding sulfuric acid. 62 Reagents and materials
6.2. 1 Sodium acetate solution: 500 g / L, filtered before use. 6 2. 2 Sulfuric acid solution: 1+3.
6.2.3 1-nitroso-2-naphthol-3,6-disulfonic acid sodium salt solution: 2g/L, filter and store in brown bottle, & 2. 4 Cobalt standard solution (1 mL of solution contains 500 g of Co): weigh 1.3150g of anhydrous cobalt sulfate (calculated with CaS0·7H2O at 500-550°C to constant weight) in a 250mL beaker, add water to dissolve, transfer to a 1000mL volumetric flask, dilute to scale with water, shake. 6.2.5 Cobalt standard solution (1mL solution contains 50 g of Co): transfer 25.0mL of cobalt standard solution (6.2.4) into a 250mL volumetric flask, dilute to scale with water, shake. 6.3. Instrument
Spectrophotometer: with 0.5cm absorption cell.
6.4 Analysis steps
6.4.1 Determination
64.1.1 According to the requirements of Table 1, transfer the test solution into a 100 mL beaker. Table 1 Amount of test solution to be transferred
Oxidation content, %
4.0~8.0
Volume of test solution to be transferred. mL
6.4.1.2 Add 5 mL of sodium acetate solution (6.2.1) to the transferred test solution, and slowly add 3 mL of nitroso-R salt solution (6.2.3) while stirring. Heat in a boiling water bath for about 2 min, take out, and immediately add 5 mL of tantalum solution (6.2.2), shake well. After cooling to room temperature, transfer the solution into a 50 mL volumetric flask, dilute to the mark, and shake well. 64.1.3 In a 50 mL volumetric flask, add 5 mL of sodium acetate solution (6.2.1), 5 mL of subunit-R salt (6.2.3), and 5 mL of sulfuric acid solution (6.2.2), dilute to the mark with water, and mix well. Use this solution as the reference solution. 6.4.1.4 After standing for 20 minutes, use a 0.5 cm absorption cell and the reference solution (6.4.1.3) as a reference to measure the absorbance at a wavelength of 53 nm on a spectrophotometer. Find the corresponding amount of cobalt in the color-developing solution from the working curve. 6.4.2 Drawing of the working curve
6.4.2.1 Transfer 0, 1.00, 2.00, -3.00, 4.00, and 5.00 mL of the cobalt standard solution (6.2.5) to six 100 mL beakers respectively. The rest is carried out according to 6.4.1.2, using the reference solution (6.4.1.3) as a reference. 6.4.2.2 After standing for 20 minutes, use a 0.5 cm absorption cell and measure the absorbance at a wavelength of 530 nm on a spectrophotometer, using the cobalt mass as the horizontal axis. The corresponding absorbance is the ordinate, and the working curve is drawn. 6.5 Expression of analysis results
The mass percentage of cobalt oxide (CoO) (X) is calculated according to formula (1): x,
Wherein: m
m,×V. ×1.271
m, ×K, ×10°
-The mass of cobalt found from the working curve, g:-The total volume of the test solution, mL;
The coefficient of cobalt conversion to cobalt oxide;
The mass of the sample, g;
-The volume of the test solution, mL,
6.6 Tolerance
HG / T 2781 1996
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.10%. 7 Determination of molybdenum trioxide content Thiocyanate spectrophotometric method 7.1 Method summarywwW.bzxz.Net
In sulfuric acid medium, hexavalent sawdust is reduced to pentavalent molybdenum with ascorbic acid. Pentavalent molybdenum and thiocyanate form an orange-red complex. Its absorbance is measured at a wavelength of 465nm on a spectrophotometer to calculate the aluminum trioxide content. Trivalent iron and thiocyanate form a blood-red complex. After adding a reducing agent, the reduction of trivalent iron to divalent iron no longer affects the determination. The presence of a certain amount of tin can make the color development complete quickly and help molybdenum maintain its pentavalent state. 7.2 Reagents and materials
7.2.1 Sulfuric acid solution: 1+1.
7.2.2 Sulfuric acid solution: 1+3.
7.2.3 Phosphoric acid solution: 1+1.
7.2.4 Ammonium ferric sulfate solution: 5g/L, each liter of solution contains 100mL of sulfuric acid solution (7.2.1) and 100mL of phosphoric acid solution (7.2.3)
7.2.5 Ascorbic acid solution: 50g/L. Store in a brown bottle or prepare it when needed. 7.2.6 Ammonium fluoride solution: 100g/L
7.2.7 Molybdenum trioxide standard solution (1nL contains 50μgMo0,) a) Weigh 0.0500g molybdenum trioxide (burn to constant weight at 500-550℃) and place it in a 250mL beaker. Add 10mL sulfuric acid solution (7.2.1) and heat to dissolve. Cool to room temperature and transfer to a 1000mL container bottle. Dilute to the mark with water and shake the spoon. b) Weigh 0.0.513g ammonium molybdate [(NH)Mo,O24·4H0)] is placed in a 250mL beaker, dissolved in water, transferred to a 1000mL volumetric flask, diluted to scale with water, shaken, 7.3 Instruments
Spectrophotometer: with 1 cm absorption cell
7.4 Analysis steps
7.4.1, Determination
7.4.1.1 According to the requirements of Table 2, transfer the test solution and place it in a 50mL volumetric flask that has been pre-added with 8mL of ammonium sulfate solution (7.2.4).
Table 2 Amount of test solution transferred
Trioxide content, %
6. 0 ~ 12. 5
12. 5 ~ 25. 0
Pipette the volume of the test solution, rαL
7.4.1.2 Add 6mL of sulfuric acid solution (7.2.1), 10mL of ammonium thiocyanate solution (7.2.6), and 10mL of ascorbic acid solution (7.2.5) to the transferred test solution, dilute to the mark with water, and shake the spoon.7.4. 1.3 at 50 In a 100 mL container bottle, add 8 mL of ammonium ferric sulfate solution (7.2.4), 6 mL of sulfuric acid solution (7.2.1), 10 mL of ammonium thiocyanate solution (7.2.6), and 10 mL of ascorbic acid solution (7.2.5), dilute to the scale with water, and use this solution as the reference solution.
7.4..4 After leaving it for 20 minutes, use a 1 cm absorption cell and the reference solution (7.4.1.3) as the reference to measure the absorbance at a wavelength of 465 nm on a spectrophotometer. Find the corresponding aluminum oxide content in the colorimetric solution from the working curve. 7.4.2 Drawing of working curve
7.4.2.1 Transfer 0, 1.00, 2.00, 3.00, 4.00 and 5.00 mL of trioxide standard solution (7.2.7) and place them respectively in six 50 mL volumetric flasks 23
HG/T2781—1996
pre-added with 8 mL of ammonium ferric sulfate solution (7.2.4). Proceed as in 7.4.1.2 for the rest. 7.4.2.2 After 20 minutes of placement, use a 1 cm absorption cell and the reference solution (7.4.1.3) as a reference to measure the absorbance at a wavelength of 465 nm on a spectrophotometer. Use the mass of aluminum oxide as the horizontal coordinate and the corresponding absorbance as the vertical coordinate to draw a working curve. 7.5 Expression of analysis results
The percentage content of molybdenum trioxide (x) is calculated according to formula (2): X, -
mg × y, × 10
In the formula: m is the mass of molybdenum trioxide obtained from the working curve, ug: V- the total volume of the test solution. mL;
mo- the mass of the sample weighed, g:
V, the volume of the test solution transferred, mL.
7.6 Allowable difference
Take the arithmetic mean of the parallel determination results as the determination result. The absolute difference of the parallel determination results shall not exceed 0.10%, 24
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