SH/T 0571-1993 Determination of Zeolite Surface Area in Catalysts

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Card type: Test method

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

• Standard number: SH/T 0571-93
• Chinese name: Determination of Zeolite Surface Area in Catalysts
• English name: not provided in the available source
• Replacement relationship: not provided in the available source (the source notes "(confirmed in 2004)")
• Approval/implementation: approved by China Petrochemical Corporation in 1993-08-19, implemented in 1994-05-01
• Drafting unit: drafted under the responsibility of the Research Institute of Petroleum Processing; technical jurisdiction: Research Institute of Petroleum Processing
• Main drafters: Zhang Xizhi, Li Guoying
• Reference adoption: ASTM D4365-85 "Standard Method for Determination of Zeolite Surface Area in Catalysts"

2. Scope of application and non-applicability

• Applicable to catalysts containing large-pore zeolites, including cracking catalysts, hydrogenation catalysts, and isomerization catalysts.
• Not applicable: not provided in the available source.

3. Method principle

At liquid nitrogen temperature, measure the volume of nitrogen adsorbed by the catalyst at different low pressures. Determine according to GB/T 5816; from the measured nitrogen adsorption amount, calculate according to the BET formula to obtain the total surface area of the catalyst; by extending the pressure range (P/Po = measured 10-15 test points between 0.01 and 0.65) and using the V-t plotting method to calculate the matrix surface area, the zeolite surface area is the difference between the catalyst surface area and the matrix surface area.

4. Reagents and materials (purity / preparation)

• 6.1 Nitrogen: cylinder nitrogen, purity not lower than 99.9%.
• 6.2 Helium: cylinder helium, purity not lower than 99.9%.
• 6.3 Liquid nitrogen: the saturated vapor pressure (Po) value is required to be not higher than the atmospheric pressure of the day 5.3 kPa.
• Preparation method: not provided in the available source.

5. Instruments and equipment

• 5.1 Fully automatic physical adsorption instrument: such as the ASAP-2400 or ASAP-2000 series as well as the classical static nitrogen adsorption volumetric apparatus may all be used as the measuring instrument for this standard, but the vacuum degree of the vacuum system is required to be higher than 1.33 Pa.
  • Note ①: The following test steps are mainly described according to the operating contents of the ASAP-2400 instrument.
  • Note ②: 1 in = 7.5 mm (the source writes "IN two 7.5mtw", requires confirmation against the source standard (source-text extraction)).
• 5.2 Analytical balance: sensitivity 0.1 mg.
• 5.3 High-temperature furnace.

6. Recommended operating conditions

• Degassing conditions: system pressure not greater than 1.33 Pa, temperature 300～350 ℃, heat for 4 h, then cool to room temperature and refill with helium to atmospheric pressure; for catalysts with high zeolite content, degassing overnight is allowed (7.1.4).
• Sample pretreatment: after heating pretreatment in a high-temperature furnace at 300 ℃, 1 h, cool to room temperature in a desiccator (7.1.1).
• BET Linear range: P/Po = 0.05～0.25, take at least four test points; when the zeolite content increases, the BET linear range may use P/Po = 0.01～0.09 (7.2.3).
• V-t Plotting linear range: the t value is preferably taken as 0.4～0.6 (P/Po = 0.15～0.44) (7.2.4).
• Sample amount: it is preferable to provide a total sample surface area of 20～100 m² (7.1.3).
• Amount of liquid nitrogen added: liquid level to the bottle mouth about 60 mm (the source writes "60nuu", requires confirmation against the source standard (source-text extraction)) (7.2.1).

7. Sampling and sample preparation

• 7.1.1 Place the sample in a high-temperature furnace and after heating pretreatment at 300 ℃, 1 h, cool to room temperature in a desiccator.
• 7.1.2 Place clean blank sample tubes at each degassing station port of the instrument, evacuate, then fill with helium to atmospheric pressure, and accurately weigh.
• 7.1.3 Roughly weigh the catalyst sample, place it into a sample tube already filled with helium, and select the sample amount so as to provide a total sample surface area of preferably 20～100 m².
• 7.1.4 Place the sample tube containing the sample at each degassing station port of the instrument, heat under conditions of system pressure not greater than 1.33 Pa and 300～350 ℃ for 4 h, then cool to room temperature and refill with helium to atmospheric pressure. Note: for catalysts with high zeolite content, degassing overnight is allowed.
• 7.1.5 Accurately weigh the degassed sample and sample tube mass to obtain the sample mass.

8. Analysis steps

• 7.2.1 Add liquid nitrogen to each sample Dewar flask (liquid level to the bottle mouth about 60 mm).
• 7.2.2 Transfer the sample tube fitted with the liquid nitrogen isothermal jacket to each analysis station port of the instrument.
• 7.2.3 Through the numeric keys on the computer keyboard, execute and control the entire test process in a window menu manner, and within the BET linear range (P/Po = 0.05～0.25) take at least four test points; within the V-t plotting linear range, at least four test points must also fall on the line. Note: when the zeolite content increases, the BET linear range may use the range P/Po = 0.01～0.09.
• 7.2.4 For selection of the V-t plotting linear range, the t value is preferably taken as 0.4～0.6 (P/Po = 0.15～0.44).

9. Qualitative and quantitative determination and calculation formulas

• 8.1 BET Surface area S_BET (m²/g) is calculated according to GB/T 5816.

• 8.2 Adsorbed layer thickness t value (nm) is calculated according to the Harkins-Jura formula, i.e., formula (1):

  t = [ 13.99 / (0.034 - log(P/Po)) ]^(1/2) × 10^(-1) (formula 1, the source is typeset as a fraction, requires confirmation against the source standard (source-text extraction))

  Where: P— adsorption equilibrium pressure, Pa; Po— saturated vapor pressure, Pa; P/Po— relative pressure.

• 8.3 Plot t against adsorption amount as a V-t graph, and use the least squares method or graphical method to obtain the slope S₁ and intercept of the straight line in the V-t graph (the intercept symbol is missing here in the source, requires confirmation against the source standard (source-text extraction)).

• 8.4 Matrix surface area S_M (m²/g) is calculated according to formula (2):

  S_M = S₁ × [ 15.47 / 0.975 ] (formula 2, the source is typeset as a fraction, requires confirmation against the source standard (source-text extraction))

  Note: 0.975— correction coefficient, applicable to oxide-type catalysts.

• 8.5 Zeolite surface area S_Z (m²/g) is calculated according to formula (3):

  S_Z = S_BET - S_M (formula 3)

• Zeolite micropore volume V_mp (μL/g) is calculated according to formula (4):

  V_mp = t₁ × 0.001547 (formula 4, the source symbol is "l,", requires confirmation against the source standard (source-text extraction))

10. Precision

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

• 9.1 Repeatability: the difference between two results of repeated determination of the same sample by the same laboratory shall not be greater than the value specified in the table below.
• 9.2 Reproducibility: for determination of the same sample by different laboratories, the difference between the results submitted by each shall not be greater than the value specified in the table below.

Precision table:

Note:

• When the zeolite surface area is between 87.2～136 m²/g and 136～174 m²/g, the precision shall be adopted by interpolation according to the table above.
• When the zeolite surface area is between 50.0～87.2 m²/g, the repeatability is 5.4% and the reproducibility is 36.5%.
• When the zeolite surface area is between 174～220 m²/g, the repeatability is 5.0% and the reproducibility is 14.5%.

11. Report

• 10.1 Take the arithmetic mean of two results of repeated determination as the zeolite surface area determination result, and take three significant figures.
• 10.2 The report shall give the sample pretreatment and degassing conditions.

12. Referenced documents

• GB/T 5816 Determination of Surface Area of Catalysts and Adsorbents

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 Q&A