Scope

1.1 This test method covers the determination of the pore volume distributions of catalysts and catalyst carriers by the method of mercury intrusion porosimetry. The range of apparent diameters of pores for which it is applicable is fixed by the operant pressure range of the testing instrument. This range is typically between apparent pore entrance diameters of about 100 and 0.003 μm (3 nm).

1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.3 WARNING—Mercury has been designated by many regulatory agencies as a hazardous material that can cause central nervous system, kidney and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury containing products. See the applicable product Material Safety Data Sheet (MSDS) for details and EPA’s website—epa.gov/mercury/faq.htm—for additional information. Users should be aware that selling mercury and/or mercury containing products into your state or country may be prohibited by law.

1.4 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific hazard information is given in Section 8.

Terminology

3.1 Definitions of Terms Specific to This Standard:

3.1.1 apparent pore diameter—the diameter of a pore, assumed to be cylindrical, that is intruded at a pressure, P, and is calculated with Eq 1.

3.1.2 interparticle pores—those pores that occur between particles when they are packed together and that are intruded during the test.

3.1.3 intraparticle pores—those pores lying within the envelopes of the individual catalyst particles and that are intruded during the test.

3.1.4 intruded pore volume—the volume of mercury that is intruding into the pores during the test after this volume has been corrected, if necessary, per 13.3.2.

Significance and Use

5.1 This test method is intended to determine the volume distribution of pores in catalysts and catalyst carriers with respect to the apparent diameter of the entrances to the pores. In general, both the size and volume of pores in a catalyst affect its performance. Thus, the pore volume distribution is useful in understanding a catalyst’s performance and in specifying a catalyst that can be expected to perform in a desired manner.

Apparatus

7.1 Mercury Intrusion Porosimeter, equipped with a sample holder capable of containing one or several catalyst or catalyst carrier particles. This holder is frequently called a penetrometer. The porosimeter shall have a means of surrounding the test specimen with mercury at a low pressure, a pressure generator to cause intrusion, pressure transducers capable of measuring the intruding pressure with an accuracy of at least 61 % throughout the range of pressures over which the pores of interest are being intruded, and a means of measuring the intruded mercury volumes with an accuracy of at least 61 mm3 (610−3 cm3).

7.2 Vacuum Pump, if not part of the porosimeter, to evacuate the sample holder.

7.3 Analytical Balance capable of measuring the sample’s mass with an accuracy of at least 60.1 %. This usually means that the balance must be sensitive to 610−7 kg (60.1 mg).

7.4 Mercury, with a purity equal to, or better than, double distilled.

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