SH/T 0344-1992 Determination of molybdenum trioxide content in hydrorefining catalysts

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Card type: Test method

1. Method number / full title / English name / replacement relationship

• Standard number: SH/T 0344-92 (confirmed in 2004)
• Chinese title: Determination of molybdenum trioxide content in hydrorefining catalysts
• English title: not provided in the available source
• Replacement relationship: replaces SH/T 2776-75 (original text is "replaces sir 2776- 7s", requires confirmation against the source standard (source-text extraction))
• Approval/implementation: approved by China Petrochemical Corporation in 1992-05-20, implemented in 1992-05-20

2. Scope of application and non-applicability

• Scope of application: This standard specifies the method for determination of molybdenum trioxide content in hydrorefining catalysts; applicable to hydrorefining catalysts.
• Not applicable: not provided in the available source.

3. Method principle

Dissolve the sample with sulfuric acid, add thiourea (original text "sulfur-N [garbled reagent name]" "[garbled thiourea name]", requires confirmation against the source standard (source-text extraction)) to reduce hexavalent molybdenum in the solution to pentavalent, and the pentavalent molybdenum then forms a red complex in the form of Mo(CNS)5 with potassium thiocyanate, then determine by colorimetry.

4. Reagents and materials (purity / preparation)

• 4.1 Sulfuric acid: analytical grade, prepare as 1:1 (by volume ratio) solution.
• 4.2 Ammonium citrate (original text "citrate [garbled cation name]", requires confirmation against the source standard (source-text extraction)): analytical grade, prepare as 300 g/L solution.
• 4.3 Thiourea (original text "[garbled thiourea name]", requires confirmation against the source standard (source-text extraction)): analytical grade, prepare as 100 g/L solution.
• 4.4 Potassium thiocyanate: analytical grade, prepare as 500 g/L solution (original text "500[unreadable unit]L", requires confirmation against the source standard (source-text extraction)).
• 4.5 Nitric acid: analytical grade, prepare as 1:1 and 1:3 (by volume ratio) solutions.
• 4.6 Sodium hydroxide: analytical grade, prepare as 200 g/L solution (original text "200[unreadable unit]L", requires confirmation against the source standard (source-text extraction)).
• 4.7 Molybdenum trioxide: spectroscopically pure.
• 3.2 Materials: pH test paper pH 1—14 (original text "[garbled prefix]test paper:pHl[unreadable separator]140", requires confirmation against the source standard (source-text extraction)).

5. Instruments and equipment

• 3.1.1 Spectrophotometer: capable of absorbance measurement in the 460 nm wavelength region.
• 3.1.2 Cooler: temperature can be maintained at 10—15 ℃.
• 3.1.3 Burette: 5 mL.
• 3.1.4 Beaker: 250 mL.
• 3.1.5 Volumetric flask: 100, 250, 1000 mL.
• 3.1.6 Graduated cylinder: 10, 20 mL.
• 3.1.7 Thermometer: 0—50 ℃.
• 3.1.8 Watch glass.
• 3.1.9 Pipette: 5 mL.
• 3.1.10 Funnel: diameter 75 mm.
• 3.1.11 Wash bottle.

6. Recommended operating conditions

• Colorimetric wavelength: 460 nm.
• Cuvette: 1 cm.
• Cooling temperature: 10—15 ℃.
• Color development standing time: after adding thiourea, stand for 5 min; after adding potassium thiocyanate, stand for 15 min; after diluting to the mark, stand for 30 min.
• Sample drying: dry at 150—155 ℃ for 1 h.
• Sample particle size: grind to about 150 mesh.

7. Sampling and sample preparation

• 6.1 Grind a representative sample to about 150 mesh, place in a 150—155 ℃ oven and dry for 1 h, weigh about 0.1 g (to the nearest 0.0002 g) into a 250 mL beaker.
• Rinse the beaker wall, add sulfuric acid solution 10 mL, place in a glass rod, cover with a watch glass, place on an electric furnace and heat, stirring occasionally; when heated until white fumes just appear, remove the beaker, cool, rinse the watch glass and beaker wall with hot water until the volume of the solution in the beaker is about 50 mL, filter this solution into a 250 mL volumetric flask, rinse the filter paper with hot water until the filtrate is no longer acidic when tested with pH test paper. After the solution cools, dilute to the mark with water and shake well.

8. Analytical procedure

• 5.1 Preparation of molybdenum trioxide standard solution: accurately weigh molybdenum trioxide 0.1000 g into a 250 mL beaker, add 200 g/L sodium hydroxide solution 10—20 mL, place on a hot plate and heat until completely dissolved, after cooling dilute with water, then transfer to a 1 L volumetric flask, dilute to the mark, and shake well. This solution contains molybdenum trioxide 0.1 mg per milliliter. This standard solution can be kept for half a year; if turbidity or precipitate appears, it should be re-prepared.
• 5.2 Drawing of the working curve: use a 5 mL burette to accurately measure molybdenum trioxide standard solution 1.00, 2.00, 3.00, 4.00, 5.00 mL, place them respectively into 100 mL volumetric flasks, place the volumetric flasks in a 10—15 ℃ cooler, add nitric acid solution (1:3) 3 drops, 300 g/L ammonium citrate solution 10 mL, sulfuric acid solution 20 mL, 100 g/L thiourea solution 10 mL. After standing for 5 min, add potassium thiocyanate solution 20 mL, after standing for 15 min, dilute to the mark with water, then stand for 30 min. Carry out a blank test simultaneously with the same reagents. Use a 1 cm cuvette, measure the absorbance at the 460 nm wavelength of the spectrophotometer. Plot the working curve with absorbance as the ordinate and molybdenum trioxide content as the abscissa.
• 6.2 Use a pipette to accurately measure 6.1 aliquot of solution 5 mL into a 100 mL volumetric flask, place the volumetric flask into a 10—15 ℃ cooler, add reagents and operate according to clause 5.2, measure the absorbance of the solution, then find the milligrams of molybdenum trioxide in the solution from the working curve.

9. Qualitative and quantitative determination and calculation formula

The content of molybdenum trioxide in the sample X[% (m/m)] is calculated according to the following formula:

X = (S · D) / (m × 1000) × 100

Where:

• S—— milligrams of molybdenum trioxide found from the working curve;
• D—— dilution factor of the sample;
• m—— mass of the sample, g.

(The original formula layout is source-text extraction noise, the denominator "[unreadable symbol]L X 11[garbled symbols]" requires confirmation against the source standard (source-text extraction); inferred as the above formula by dimensions, requires confirmation against the source standard (source-text extraction).)

10. Precision

Repeatability: the difference between two results of repeated determinations by the same operator shall not exceed 10% of their arithmetic mean.

11. Report

Take the arithmetic mean of two results of repeated determinations as the determination result.

12. Referenced documents

not provided in the available source.

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick reference Q&A