SH/T 0342-1992 Method for determination of iron content in reforming catalysts

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Card type: Test method

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

• Standard number: SH/T 0342-92
• Full name: Method for determination of iron content in reforming catalysts
• English name: not provided in the available source
• Replacement relationship: replaces SY 2773-78
• Other: confirmed in the year 2004; approved by China Petrochemical Corporation 1992-05-20, implemented on 1992-05-20

2. Scope of application and non-applicability

• Scope of application: This standard applies to fresh reforming catalysts.
• Non-applicability: not provided in the available source.

3. Method principle

The sample is dissolved with sulfuric acid, hydrochloric acid, and hydrogen peroxide. Under the condition that the pH of the solution is pH to 4 to 5, trivalent iron in the solution is reduced to divalent iron by hydroxylamine hydrochloride, and then forms a red complex [Fe(C12H8N2)3]²⁺ with phenanthroline, and is determined by colorimetry.

4. Reagents and materials (purity / preparation)

• 4.1 Sulfuric acid: analytical grade, prepared as a 1:1 (by volume ratio) solution.
• 4.2 Hydrochloric acid: analytical grade, prepared as 1:1 and 1:9 (by volume ratio) solutions.
• 4.3 30% Hydrogen peroxide: analytical grade.
• 4.4 Sodium acetate: analytical grade, prepared as a 300 g/L solution.
• 4.5 Hydroxylamine hydrochloride: analytical grade, prepared as a 10 g/L solution.
• 4.6 Phenanthroline: analytical grade, prepared as a 1.5 g/L solution (the source text at source-text extraction reads “1.5[unreadable character]L”, requires confirmation against the source standard (source-text extraction)).
• 4.7 Glacial acetic acid: analytical grade.
• 4.8 Iron wire: purity of 99.9% or above (or spectrally pure iron powder).
• 4.9 Water: deionized water, conductivity not greater than 5 μS/cm (the source text at source-text extraction reads “5[6/cm”, requires confirmation against the source standard (source-text extraction)).

5. Instruments and equipment

• 3.1 Spectrophotometer: capable of measuring absorbance in the wavelength region of 490 nm.
• 3.2 Beaker: 250, 500 mL.
• 3.3 Volumetric flask: 100, 1000 mL.
• 3.4 Measuring cup: 25 mL.
• 3.5 Pipette: 10, 20 mL.
• 3.6 Burette: 10 mL (the source text at source-text extraction reads “l0, nLo”, requires confirmation against the source standard (source-text extraction)).
• 3.7 Dropping bottle.
• 3.8 Watch glass.
• 3.9 High-temperature furnace.

6. Recommended operating conditions

• Color development pH: 4 to 5.
• Measurement wavelength: 490 nm.
• Cuvette: 3 cm.
• Color development standing time: 30 min.
• Ignition basis measurement temperature: 850 ℃, constant temperature 1 h.

7. Sampling and sample preparation

• Grind the sample to about 150 mesh.
• Weigh about 0.5 g (to the nearest 0.0002 g) into a 250 mL beaker.
• Ignition basis measurement: while weighing the sample in 6.1, weigh 0.5 to 1 g (to the nearest 0.0002 g) of sample into a constant-weight covered porcelain crucible.

8. Analytical procedure

• 6.1 Sample dissolution: grind the sample to about 150 mesh, weigh about 0.5 g (to the nearest 0.0002 g) into a 250 mL beaker, rinse the beaker wall with a small amount of water, add 1:1 sulfuric acid solution 15 mL, cover with a watch glass, place on an electric furnace and heat, stirring occasionally, heat until sulfuric acid just emits white fumes, remove the beaker and cool. Then add 20 mL hydrochloric acid solution (1:1), 2 mL 30% hydrogen peroxide, until no more bubbles are emitted, then place on the electric furnace and heat over low heat until sulfuric acid white fumes appear, remove the beaker and cool. Rinse the watch glass and beaker wall with water until the solution volume in the beaker is about 50 mL. Place on the electric furnace and boil, then remove and cool, transfer to a 100 mL volumetric flask, dilute to the mark with water, and mix well. If the boiled solution has suspended matter, it must be filtered and washed with hot water.
• 6.2 Determination: use a pipette to accurately measure 6.1 of the solution from step 20 mL into a 100 mL volumetric flask, then add reagents according to step 5.3 (no need to add sulfuric acid) for determination. The measured absorbance is used to find the milligrams of iron in the test solution from the working curve.
• 6.3 Determination of ignition basis:
  • 6.3.1 While weighing the sample in step 6.1, weigh 0.5 to 1 g (to the nearest 0.0002 g) of sample into a constant-weight covered porcelain crucible, place in a high-temperature furnace, raise the temperature to 850 ℃, hold at constant temperature for 1 h, then remove, place in a desiccator to cool to room temperature (about 0.5 h), and weigh.
  • 6.3.2 Ignition basis B[%(m/m)] is calculated according to formula (1): B = (m2 − m0)/(m1 − m0) × 100 (the formula in the source text at source-text extraction is incomplete, requires confirmation against the source standard (source-text extraction)). Where: m0— mass of the crucible after constant weight, g; m1— mass of the sample before ignition, g; m2— total mass of the sample and crucible after ignition, g. Take the arithmetic mean of the results of repeated tests as the ignition basis.
• 5.3 Drawing of the working curve: use a 10 mL burette to accurately measure standard solution containing 0.01 mg of iron per milliliter, 1.00, 2.00, 3.00, 4.00, 5.00 mL, respectively, into 100 mL volumetric flasks, then respectively add sulfuric acid solution (1:1) 3 mL (the source text at source-text extraction reads “3.L”, requires confirmation against the source standard (source-text extraction)), 300 g/L sodium acetate 20 mL, 10 g/L hydroxylamine hydrochloride 10 mL, 1.5 g/L phenanthroline 15 mL, dilute to the mark with water, and mix well. After standing for 30 min, simultaneously carry out a blank test with the same reagents, use a 3 cm cuvette, and measure the absorbance at the wavelength of 490 nm on the spectrophotometer. Plot the working curve with absorbance as the ordinate and milligrams of iron as the abscissa.

9. Qualitative and quantitative determination and calculation formula

• Preparation of iron standard solution (5.2):
  • Accurately weigh 1.0000 g of iron wire (or iron powder) into a 250 mL beaker, add 25 mL hydrochloric acid solution (1:1), place on an electric furnace and heat to dissolve. After cooling, transfer to a 1 L volumetric flask, then dilute to the mark with water, and mix well. This solution contains 1 mg of iron per milliliter.
  • Accurately pipette 10 mL of the above solution into a 1 L volumetric flask, and dilute to the mark with water. This solution contains 0.01 mg of iron per milliliter.
  • Note: The iron standard solution may also be prepared from analytical grade ammonium ferrous sulfate. Accurately weigh 0.702 g of ammonium ferrous sulfate hexahydrate [(NH4)2Fe(SO4)2·6H2O] (the source text at source-text extraction reads “。.(Y702g[garbled reagent name](Nlia)2Fe[unreadable character])2.6112。”, requires confirmation against the source standard (source-text extraction)) into a 250 mL beaker, add a small amount of water and 100 mL hydrochloric acid solution (1:9), stir to dissolve, transfer to a 1 L volumetric flask, dilute to the mark with water, and mix well. This solution contains 0.01 mg of iron per milliliter.
  • The iron standard solution may be kept for half a year; if it becomes turbid or has precipitate during this period, it should be re-prepared.
• Preparation of phenanthroline solution (5.1): weigh 1.5 g of phenanthroline, add a small amount of water and 10 mL of glacial acetic acid, heat to dissolve, then cool, then transfer to a 1 L volumetric flask, and dilute to the mark with water.
• Calculation formula (7): The iron content in the sample x[%(m/m)] is calculated according to formula (2): x = (S × D)/(m × B × 1000) × 100 (the formula in the source text at source-text extraction is incomplete, requires confirmation against the source standard (source-text extraction)). Where: S— milligrams of iron found from the working curve; D— dilution factor of the sample; m— mass of the sample, g; B— ignition basis, %(m/m).

10. Precision

Repeatability: the difference between two results of repeated determinations by the same operator shall not be greater than 20% 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