NB/SH/T 0570-2017 Determination of platinum content in reforming catalysts - Spectrophotometric method

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Card type: Test method

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

• Standard number: NB/SH/T 0570—2017
• Chinese title: Determination of platinum content in reforming catalysts - Spectrophotometric method
• English title: Standard test method for pplatimum in reforming catalyst by spectrophotometry (as in the source text, suspected to be platinum spelling noise, requires confirmation against the source standard (source-text extraction))
• Replacement relationship: replaces SH/T 0570—1993 'Method for determination of platinum content in reforming catalysts'
• Adoption relationship: modified adoption using the redrafting method of ASTM D4642-04 (2016) 'Determination of platinum content in reforming catalysts - Wet chemical method'
• Publication/implementation: published on 2017-12-27, implemented on 2018-05-01
• Issuing authority: National Energy Administration

2. Scope of application and non-applicability

• This standard specifies the method for determination of platinum content in reforming catalysts.
• Applicable to fresh and used monometallic platinum, platinum-tin, and platinum-rhenium reforming catalysts with alumina as the carrier.
• The platinum mass fraction range is 0.200%~0.700%.
• When determining platinum-rhenium catalysts, the rhenium content in the platinum complex color-developing solution shall be controlled to not more than 15wg/mL (the unit is as in the source text, suspected to be μg/mL, requires confirmation against the source standard (source-text extraction)).
• The presence of palladium, ruthenium, and rhodium elements significantly interferes with the determination of platinum.
• As long as it is confirmed that the presence of metal elements in the catalyst does not interfere with the determination of platinum, this standard may also be applicable to other platinum-containing catalysts with activated alumina as the carrier.

3. Method principle

After the sample is subjected to high-temperature treatment at 550°C, it is dissolved with hydrochloric acid, phosphoric acid, and hydrogen peroxide. The tetravalent platinum in the solution reacts with the reducing agent stannous chloride under a certain hydrochloric acid acidity to form a yellow chloroplatinic acid tin complex (the extracted name of the complex is garbled; requires confirmation against the source standard (source-text extraction)). The absorbance of the color-developing solution of this complex is measured with a spectrophotometer, and the platinum content in the sample is calculated by converting the absorbance through the average conversion factor.

4. Reagents and materials (purity / preparation)

• 6.1 Hydrochloric acid: analytical grade, mass fraction 35%~38% (the source extraction contains an unreadable character before 35%~38%; requires confirmation against the source standard (source-text extraction))
• 6.2 Hydrochloric acid solution: hydrochloric acid (6.1) and water are mixed by volume ratio to prepare 1:1 hydrochloric acid solution
• 6.3 Phosphoric acid: analytical grade, mass fraction ≥85%
• 6.4 Nitric acid: analytical grade, mass fraction 65%~68%
• 6.5 Formic acid (HCOOH): analytical grade, mass fraction ≥88.0%
• 6.6 Stannous chloride (SnCl₂·2H₂O): analytical grade (source text 'SnCl•2H.0', requires confirmation against the source standard (source-text extraction))
• 6.7 Hydrogen peroxide: analytical grade, mass fraction ≥30%
• 6.8 Platinum wire: purity not less than 99.99%
• 6.9 Water: meets the requirements for grade three water in GB/T 6682—2008
• 7.1 280g/L Preparation of stannous chloride solution: weigh 280g stannous chloride (6.6), dissolve in 500mL hydrochloric acid (6.1), heat until completely dissolved, dilute with water to 1L, and shake well. This solution must be prepared on the same day.
• 7.2 1mg/mL Preparation of platinum standard stock solution: weigh about 1g (accurate to 0.1mg) platinum wire (6.8) into a 250mL beaker, add 7mL nitric acid (6.4), 21mL hydrochloric acid (6.1), cover the beaker with a watch glass, and heat slowly on an electric furnace at 85°C. When the solution becomes thick, add 7mL nitric acid (6.4) and 21mL hydrochloric acid (6.1) until the platinum wire is completely dissolved, then evaporate to near dryness. After cooling, add 20mL hydrochloric acid solution (6.2) to wash the watch glass and beaker walls, and evaporate to dryness again. After cooling, use about 20mL hydrochloric acid solution (6.2) to wash the watch glass and beaker walls, and dissolve the evaporated residue. Add a few drops of formic acid (6.5) to the solution to reduce the remaining nitric acid. Transfer the solution with water to a 1L volumetric flask, add 300mL hydrochloric acid (6.1), shake well, and dilute with water to near the mark. After the solution cools to room temperature, dilute with water to the mark and shake well. The platinum concentration of this stock solution is 1mg/mL.
• 7.3 0.1mg/mL Preparation of platinum standard working solution: accurately pipette the platinum standard stock solution (7.2) 10mL into a 100mL volumetric flask, add 30mL hydrochloric acid (6.1), shake well, and dilute with water to near the mark. After the solution cools to room temperature, dilute with water to the mark and shake well. The platinum concentration of this solution is 0.1mg/mL.

5. Instruments and equipment

• 5.1 Spectrophotometer: wavelength range 200nm~800nm; when the absorbance is 1.0, the repeatability is ±0.002
• 5.2 Cuvette: 1cm
• 5.3 Analytical balance: sensitivity 0.1mg
• 5.4 Muffle furnace: 1000°C±25°C (source text '1000C+25°', requires confirmation against the source standard (source-text extraction))
• 5.5 Porcelain crucible: 30mL
• 5.6 Vacuum desiccator: desiccant is 4A molecular sieve
• 5.7 Beaker: 200mL, 250mL
• 5.8 Watch glass: diameter 85mm
• 5.9 Volumetric flask: 100mL, 1000mL
• 5.10 Graduated measuring cup: 10mL, 50mL, 100mL
• 5.11 Burette: 25mL, graduation value 0.10mL
• 5.12 Pipette: 10mL (source text '10ml')
• 5.13 Weighing bottle: 25mm×40mm
• 5.14 Polyethylene wash bottle: 500mL (source text '500ml')
• 5.15 Porcelain evaporating dish: 250mL (source text '250ml')
• 5.16 Electric furnace

6. Recommended operating conditions

• High-temperature treatment temperature: 550°C±25°C (for fresh catalyst and used catalyst coke-burning treatment)
• Ignition basis determination temperature: 1000°C±25°C, constant temperature 3h
• Color development standing time: 1h
• Measurement wavelength: 403nm (monometallic platinum and platinum-tin reforming catalysts); 460nm (platinum-rhenium reforming catalyst)
• Cuvette: 1cm
• Total solution volume: not more than 60mL (before transferring to the 100mL volumetric flask after dissolution)
• Platinum content range: 0.5mg~1.5mg (according to clause 7.4)

7. Sampling and sample preparation

• 8.1.1 Fresh catalyst: requires high-temperature treatment at 550°C. Take 3g–5g catalyst sample into a 250mL porcelain evaporating dish, perform high-temperature treatment in a muffle furnace at 550°C±25°C (with the furnace door slightly open), shake the sample 1 times–2 times during the process, and after high-temperature treatment to above 2h, remove and cool. Grind to a particle size less than 0.104mm and mix well. Warning: Beware of high temperature.
• Sample weight is specified in Table 1:

Table 1 Sample weighing specification

Note: When the sample solution is also to be used for determination of other elements (such as rhenium) besides platinum content, the sample weight may be increased [for example, when the platinum mass fraction is 0.400%, weigh about 1g sample (accurate to 0.1mg)], dissolve the sample according to the dissolution method in 8.1.1, and transfer to a 100mL volumetric flask, dilute with water to the mark, and shake well. Pipette a portion of the solution into a 100mL volumetric flask so that the platinum content still complies with clause 7.4 within the range of 0.5mg~1.5mg, and dilute with water to not exceed 60mL. The remaining solution is for determination of other elements.

• 8.1.2 Used catalyst: if there is carbon deposit as above, coke-burning treatment is required first. Take about 10g catalyst sample free of other impurities into a 250mL porcelain evaporating dish, perform coke-burning treatment in a muffle furnace at 550°C±25°C (with the furnace door slightly open), shake the sample 1 times~2 times during the process, and after coke-burning treatment to above 2h, remove and cool. Warning: Beware of high temperature. For the sample after coke burning, the grinding particle size, sample amount, and requirements for platinum content are the same as 8.1.1.

8. Analytical procedure

• 7.4 Determination of conversion factor (K): Use a 25mL burette to accurately measure the platinum standard solution from clause 7.3, 5.00mL, 10.00mL, 15.00mL, and place them respectively into three 100mL volumetric flasks, then add 30mL hydrochloric acid (6.1) to each, then dilute with water to about 85mL. After cooling to room temperature, add 10mL stannous chloride solution (7.1), dilute with water to the mark, and shake well. Prepare a reagent blank solution at the same time. After standing for 1h, using the reagent blank solution as reference, use a 1cm cuvette to measure the absorbance at the wavelength of 403nm or 460nm on the spectrophotometer (403nm is the wavelength used for determination of platinum in monometallic platinum and platinum-tin reforming catalysts; 460nm is the wavelength used for determination of platinum in platinum-rhenium reforming catalysts), and calculate the ratio (K) of the platinum milligram amount (m₀) at each point to the corresponding absorbance (A). The average value is the average conversion factor K average. This factor represents the milligrams of platinum equivalent to unit absorbance. The absorbance measurement in this item and the sample measurement shall be carried out simultaneously.
• 8.1.1 Dissolution: Place the ground sample into a weighing bottle, weigh the sample (m₁) in the amount specified in Table 1 into a 200mL beaker, so that the platinum content is within the range of 0.5mg~1.5mg according to clause 7.4. Wash the beaker walls with about 15mL water and moisten the sample. First add 10mL phosphoric acid (6.3), cover with a watch glass, place on an electric furnace and heat slowly to dissolve until fumes appear and platinum black precipitates, then remove the beaker and allow to cool slightly, wash the watch glass and beaker walls with water, then add 10mL hydrochloric acid (6.1) and 1mL hydrogen peroxide (6.7), continue heating slowly until the platinum black dissolves, remove and allow to cool slightly, wash the watch glass and beaker walls with water, then gently boil on the electric furnace for 5min to remove excess hydrogen peroxide, after cooling, transfer the solution with water to a 100mL volumetric flask, the total volume of the solution must not exceed 60mL.
• 8.2 Determination of the sample: Add 25mL hydrochloric acid (6.1) to the sample solution from clause 8.1, shake well, after cooling to room temperature, add 10mL stannous chloride solution (7.1), dilute to the mark with water, shake well. Simultaneously prepare a reagent blank solution. Allow to stand for 1h, using the reagent blank solution as reference, for monoplatinum and platinum-tin reforming catalyst samples at wavelength 403nm; for platinum-rhenium reforming catalyst samples at wavelength 460nm, measure the absorbance (A) using a 1cm cuvette.
• 8.3 Determination of the ignition basis:
  • 8.3.1 The platinum content of reforming catalysts is calculated on a non-volatile basis. Usually, while weighing the sample, a portion of the sample is weighed out to determine the ignition basis.
  • 8.3.2 Weigh three portions of about 1g each (accurate to 0.1mg) of sample (m₂) into three constant-weight porcelain crucibles (m₃), cover with lids but leave a small gap, place in a muffle furnace, raise the temperature to 1000°C±25°C, hold at constant temperature for 3h, then remove, after slight cooling place in a vacuum desiccator to cool for 1h, then weigh (m₄), to obtain the ignition basis for each sample portion (B). Warning: Beware of high temperature.
  • 8.3.3 When used for calculating the platinum mass fraction, the average ignition basis (B average) is taken as the average of the ignition bases (B) of the three sample portions.

9. Qualitative and Quantitative and Calculation Formulas

• 9.1 The ignition basis of the sample is expressed as mass fraction B, the value expressed as a percentage, calculated according to formula (1): B = (m₄ − m₃) / m₂ × 100 Where:
  • m₄—total mass of sample and crucible after ignition, in grams (g)
  • m₃—mass of empty crucible, in grams (g)
  • m₂—mass of sample before ignition, in grams (g)
• 9.2 The platinum conversion factor is expressed as K, the value expressed as milligrams of platinum equivalent to unit absorbance, calculated according to formula (2): K = m₀ / A Where:
  • m₀—mass of platinum in the colored solution, in milligrams (mg)
  • A— absorbance of the colored solution
• 9.3 The mass fraction of platinum in the sample is expressed as X, the value expressed as a percentage, calculated according to formula (3): X = (A × K average) / (m₁ × B average × 1000) × 100 Where:
  • A— absorbance after platinum color development in the sample solution
  • K average—average conversion factor, milligrams of platinum equivalent to unit absorbance, in milligrams (mg)
  • m₁—mass of sample, in grams (g)
  • B average—average ignition basis

10. Precision

Judge the reliability of test results according to the following provisions (95% confidence level):

• 10.1 Repeatability: In the same laboratory, by the same operator, using the same instruments, the difference between two results of repeated determinations on the same sample shall not exceed 0.005%.
• 10.2 Reproducibility: In different laboratories, by different operators, using different instruments, the difference between the arithmetic means of two independent results obtained from determinations on the same sample shall not exceed 0.013%.

11. Report

Take the arithmetic mean of two repeated determination results as the determination result, and retain three decimal places.

12. Reference Documents

• GB/T 6682—2008 Water specifications and test methods for analytical laboratory use
• ASTM D4642-04 (2016) "Determination of Platinum Content in Reforming Catalysts - Wet Chemical Method" (modified adoption)

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 for Questions and Answers