71.040.30 (Chemical reagents) 标准查询与下载

ASTM D4058-96(2006) 催化剂及其载体磨损的标准试验方法

This test method is considered to be a measure of the propensity of a catalyst to produce fines in the course of transportation, handling, and use. However, there is no absolute level of acceptability. The values obtained are significant principally in relation to values for other materials (or other samples of the same material) of comparable size.1.1 This test method covers the determination of the attrition and abrasion resistance of catalysts and catalyst carriers. It is applicable to tablets, extrudate, spheres, and irregularly shaped particles larger than about 1/16 in. (1.6 mm) and smaller than about 3/4 in. (19 mm). The materials used in developing the method exhibited losses on attrition less than 7 %; however, the method should be applicable to materials giving much higher attritions.1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.This standard does not purport to address all of the safety concerns, 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.

Standard Test Method for Attrition and Abrasion of Catalysts and Catalyst Carriers

ASTM D4463/D4463M-96(2012)e1 淡水分裂催化剂的金属自由蒸汽去活化作用的标准指南

In general, steam treatment of FCC catalyst can be used either to compare a series of cracking catalysts at a simulated equilibrium condition or conditions, or to simulate the equilibrium condition of a specific cracking unit and a specific catalyst. This guide gives an example for the first purpose and an approach for the latter purpose.1.1 This guide covers the deactivation of fresh fluid catalytic cracking (FCC) catalyst by hydrothermal treatment prior to the determination of the catalytic cracking activity in the microactivity test (MAT). 1.2 The hydrothermal treatment of fresh FCC catalyst, prior to the MAT, is important because the catalytic activity of the catalyst in its fresh state is an inadequate measure of its true commercial performance. During operation in a commercial cracking unit, the catalyst is deactivated by thermal, hydrothermal and chemical degradation. Therefore, to maintain catalytic activity, fresh catalyst is added (semi) continuously to the cracking unit, to replace catalyst lost through the stack or by withdrawal, or both. Under steady state conditions, the catalyst inventory of the unit is called equilibrium catalyst. This catalyst has an activity level substantially below that of fresh catalyst. Therefore, artificially deactivating a fresh catalyst prior to determination of its cracking activity should provide more meaningful catalyst performance data. 1.3 Due to the large variations in properties among fresh FCC catalyst types as well as between commercial cracking unit designs or operating conditions, or both, no single set of steam deactivation conditions is adequate to artificially simulate the equilibrium catalyst for all purposes. 1.3.1 In addition, there are many other factors that will influence the properties and performance of the equilibrium catalyst. These include, but are not limited to: deposition of heavy metals such as Ni, V, Cu; deposition of light metals such as Na; contamination from attrited refractory linings of vessel walls. Furthermore, commercially derived equilibrium catalyst represents a distribution of catalysts of different ages (from fresh to >300 days). Despite these apparent problems, it is possible to obtain reasonably close agreement between the performances of steam deactivated and equilibrium catalysts. It is also recognized that it is possible to steam deactivate a catalyst so that its properties and performance poorly represent the equilibrium. It is therefore recommended that when assessing the performance of different catalyst types, a common steaming condition be used. Catalyst deactivation by metals deposition is not addressed in this guide. 1.4 This guide offers two approaches to steam deactivate fresh catalysts. The first part provides specific sets of conditions (time, temperature and steam pressure) that can be used as general pre-treatments prior to comparison of fresh FCC catalyst MAT activities (Test Method D3907) or activities plus selectivities (Test Method D5154). 1.4.1 The second part provides guidance on how to pretreat catalysts to simulate their deactivation in a specific FCCU and suggests catalyst properties which can be used to judge adequacy of the simulation. This technique is especially useful when examining how different types of catalyst may perform in a specific FCCU, provided no other changes (catalyst addition rate, regenerator temperature, contaminant metals levels, etc.) occur. This approach covers catalyst physical properties that can be used as monitors to indicate the closeness to equilibrium catalyst properties. 1.5 The values stated in either SI units or inch-pound units are to be regarded separately as stand......

Standard Guide for Metals Free Steam Deactivation of Fresh Fluid Cracking Catalysts

ASTM D4937-96(2006)e1 用气相色谱法测试p-苯二胺抗降解剂纯度的标准试验方法

This test method is designed to assess the relative purity of production PPDs. These additives are primarily used as antiozonants for tires and other rubber or polymeric products. Since the results of this test method are based on area normalization, it assumes that all components are eluted from the column and each component has the same detector response. Although this is not strictly true, the errors introduced are relatively small and much the same for all samples; thus, they can be ignored since the intent of the test method is to establish relative purity. Although trace amounts of “low boilers” are present in production samples, they are disguised by the solvent peak when using packed columns (Procedure A).1.1 This test method covers the determination of the purity of Class I, II, and III p-phenylenediamine (PPD) antidegradants as described in Classification D 4676 by gas chromatography (GC) detection and area normalization for data reduction. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.This standard does not purport to address all of the safety concerns, 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.

Standard Test Method forp-Phenylenediamine Antidegradants Purity by Gas Chromatography

ASTM D4058-96(2001) 催化剂及其载体磨损的标准试验方法

1.1 This test method covers the determination of the attrition and abrasion resistance of catalysts and catalyst carriers. It is applicable to tablets, extrudate, spheres, and irregularly shaped particles larger than about 1/16 in. (1.6 mm) and smaller than about 3/4 in. (19 mm). The materials used in developing the method exhibited losses on attrition less than 7%; however, the method should be applicable to materials giving much higher attritions. 1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, 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.

Standard Test Method for Attrition and Abrasion of Catalysts and Catalyst Carriers

ASTM D2854-96(2004) 活性碳的表面密度的标准试验方法

This test method provides a method for determining the packed density of a bed of granular activated carbon. Determination of the packed density is essential when designing vessels to hold the material and for ordering purposes when procuring materials to fill existing vessels. FIG. 1 Assembly of Apparatus1.1 This test method covers the determination of the apparent density of granular activated carbon. For purposes of this test method, granular activated carbon is defined as a minimum of 90% being larger than 80 mesh. 1.2 This standard does not purport to address all of the safety concerns, 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.

Standard Test Method for Apparent Density of Activated Carbon

ASTM D2854-96(2000) 活性碳的表面密度的标准试验方法

1.1 This test method covers the determination of the apparent density of granular activated carbon. For purposes of this test method, granular activated carbon is defined as a minimum of 90% being larger than 80 mesh. 1.2 This standard does not purport to address all of the safety concerns, 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.

Standard Test Method for Apparent Density of Activated Carbon

ASTM D4069-95(2008) 从气流中除去气态放射性碘用的浸渍活性炭的标准规范

Activated carbons used in containment systems for nuclear reactors must be capable of functioning under both normal operating conditions and those conditions which may exist following a design basis accident (DBA). Adsorbent beds that are part of recirculatory systems inside containment may be exposed to the peak pressure, temperature, and steam content of a post-DBA condition. Carbon beds outside containment will be protected by fast-acting shutoff valves from the sudden rise in pressure, temperature, and humidity of the containment atmosphere which would exist following a DBA. However, some rise in temperature and humidity will be experienced even by beds outside containment if they are reconnected to containment after the initial pressure rise (due to escape of steam into the containment volume) has been reduced by containment coolers. The amount of radioactivity that can reach either type of adsorption system is conceivably quite high; hence, there is a possibility of a bed temperature rise due to decay heating. The gaseous radioactive contaminants of most interest are organic iodides. In this test, CH3I is used to typify the performance of the carbon on organic iodine compounds in general. The test described here provide a reasonable picture of the effectiveness of an activated carbon for organic iodides under normal and post-DBA conditions. The equipment and methods described can be used, with discretion, for similar tests at different gas flow conditions and, to some extent, on different gaseous radioactive contaminants and other adsorbents. 1.1 This standard covers the specifications for physical properties and performance requirements of virgin impregnated activated carbon to be used for the removal of gaseous radioiodine species from gas streams. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

Standard Specification for Impregnated Activated Carbon Used to Remove Gaseous Radio-Iodines from Gas Streams

ASTM D5160-95(2008) 活性碳气相吸收检验的标准指南

Activated carbon is used extensively for removing gases and vapors from air or other gas streams. The physical and chemical characteristics of an activated carbon can strongly influence its suitability for a given application. The procedure in this guide allows the evaluation of the dynamic adsorption characteristics of an activated carbon for a particular adsorbate under conditions chosen by the user. It is necessary that the user choose test conditions that are meaningful for the application (see Section 9). This guide can also be used to evaluate activated carbons that have been impregnated with materials to enhance their effectiveness at removing gases otherwise poorly adsorbed on activated carbon. The procedure given in this guide is not generally applicable for evaluation of carbons used as catalysts for such purposes as decomposition of low levels of ozone or oxidation of SO2 to SO 3. The procedure given in this guide can be applied to reactivated or regenerated activated carbons. Fig. 1 shows the adsorbate concentration profile in an activated carbon bed at breakthrough. The bed has a zone at the inlet in which the adsorbate concentration is equal to the influent concentration. In this region the carbon is at equilibrium with adsorbate. The adsorbate concentration in the remainder of the bed drops until at the outlet it is equal to the breakthrough concentration. The shorter the length of this mass transfer zone (adsorption zone), the more effectively the carbon in the bed is utilized. A bed whose depth is less than the length of this zone will show immediate appearance of adsorbate in the effluent (breakpoint). From the standpoint of best carbon utilization it is desirable to choose a carbon which will give as short a mass transfer zone as possible under use conditions. However, in many applications, high adsorptive capacity is more important than a short mass transfer zone. In almost every application, bed pressure drop is also a primary consideration. In a few situations such as respiratory protection against low levels of extremely toxic gases such as radioactive methyl iodide, a short mass transfer zone (that is, high adsorption rate coefficient) is more important than ultimate capacity. In other cases such as solvent recovery, a high dynamic capacity is more important. Although the design of adsorber beds is beyond the scope of this guide, the following points should be considered. The bed diameter should be as large as possible in order to lower the pressure drop and to maximize the amount of carbon in the bed. Subject to pressure drop constraints, the deepest possible carbon bed should be used. All else being equal, the use of smaller particle size carbon will shorten the mass transfer zone and improve bed efficiency at the expense of higher pressure drop. If pressure drop considerations are critical, some particle morphologies offer less resistance to flow than others. The two parameters obtained by the procedure in this guide can be used as an aid in selecting an activated carbon and in sizing the adsorption bed in which this carbon will be used. The best carbon for most applications should have a high dynamic capacity for the adsorbate No coupled with a short mass transfer zone (small dc) when evaluated under the operating conditions anticipated for the adsorber. FIG. 1 Concentration Profile of an Activated Carbon Bed at Breakthrough1.1 This guide covers the evaluation of activated carbons for gas-phase adsorption. It presents a procedure for determining the dynamic adsorption capacity, N

Standard Guide for Gas-Phase Adsorption Testing of Activated Carbon

ASTM D4365-95(2008) 测定催化剂微孔体积和沸石面积的标准试验方法

This gas adsorption method complements the X-ray procedure of Test Method D 3906. This test method will be useful to laboratories that do not have X-ray diffractometers. Each test method can be calibrated by use of an appropriate series of mechanical mixtures to provide what may be termed percent zeolite. If there is disorder in the zeolite, the adsorption method will yield higher values than the X-ray method. The reverse will be true if some zeolite pores (micropores) are blocked or filled.1.1 This test method covers the determination of total surface area and mesopore area. From these results are calculated the zeolite area and micropore volume of a zeolite containing catalyst. The micropore volume is related to the percent zeolite in the catalyst. The zeolite area, a number related to the surface area within the zeolite pores, may also be calculated. Zeolite area, however, is difficult to intepret in physical terms because of the manner in which nitrogen molecules pack within the zeolite. 1.2 This standard does not purport to address all of the safety concerns, 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. For a specific precautionary statement, see Note 3.

Standard Test Method for Determining Micropore Volume and Zeolite Area of a Catalyst

ASTM D4365-95(2001) 测定催化剂微孔体积和沸石区域的标准试验方法

1.1 This test method covers the determination of total surface area and mesopore area. From these results are calculated the zeolite area and micropore volume of a zeolite containing catalyst. The micropore volume is related to the percent zeolite in the catalyst. The zeolite area, a number related to the surface area within the zeolite pores, may also be calculated. Zeolite area, however, is difficult to intepret in physical terms because of the manner in which nitrogen molecules pack within the zeolite. 1.2 This standard does not purport to address all of the safety concerns, 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. For specific precautionary statement, see Note 2.

Standard Test Method for Determining Micropore Volume and Zeolite Area of a Catalyst

ASTM D4780-95(2007) 用多点氪吸附法测定催化剂的低表面面积的标准试验方法

This test method has been found useful for the determination of the specific surface area of catalysts and catalyst carriers in the range from 0.05 to 10 m2/g for materials specification, manufacturing control, and research and development in the evaluation of catalysts. The determination of surface area of catalysts and catalyst carriers above 10 m2/g is addressed in Test Method D 3663.1.1 This test method covers the determination of the specific surface area of catalysts and catalyst carriers in the range from 0.05 to 10 m2/g. A volumetric measuring system is used to obtain at least three data points which fall within the linear BET region.1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.This standard does not purport to address all of the safety concerns, 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.

Standard Test Method for Determination of Low Surface Area of Catalysts by Multipoint Krypton Adsorption

ASTM D4365-95(2007)e1 测定催化剂微孔体积和沸石区域的标准试验方法

This gas adsorption method complements the X-ray procedure of Test Method D 3906. This test method will be useful to laboratories that do not have X-ray diffractometers. Each test method can be calibrated by use of an appropriate series of mechanical mixtures to provide what may be termed percent zeolite. If there is disorder in the zeolite, the adsorption method will yield higher values than the X-ray method. The reverse will be true if some zeolite pores (micropores) are blocked or filled.1.1 This test method covers the determination of total surface area and mesopore area. From these results are calculated the zeolite area and micropore volume of a zeolite containing catalyst. The micropore volume is related to the percent zeolite in the catalyst. The zeolite area, a number related to the surface area within the zeolite pores, may also be calculated. Zeolite area, however, is difficult to intepret in physical terms because of the manner in which nitrogen molecules pack within the zeolite.1.2 This standard does not purport to address all of the safety concerns, 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. For a specific precautionary statement, see Note 3.

Standard Test Method for Determining Micropore Volume and Zeolite Area of a Catalyst

ASTM D5160-95(2014) 活性炭气相吸附试验的标准指南

5.1 Activated carbon is used extensively for removing gases and vapors from air or other gas streams. The physical and chemical characteristics of an activated carbon can strongly influence its suitability for a given application. The procedure in this guide allows the evaluation of the dynamic adsorption characteristics of an activated carbon for a particular adsorbate under conditions chosen by the user. It is necessary that the user choose test conditions that are meaningful for the application (see Section 9). 5.2 This guide can also be used to evaluate activated carbons that have been impregnated with materials to enhance their effectiveness at removing gases otherwise poorly adsorbed on activated carbon. 5.3 The procedure given in this guide is not generally applicable for evaluation of carbons used as catalysts for such purposes as decomposition of low levels of ozone or oxidation of SO2 to SO3. 5.4 The procedure given in this guide can be applied to reactivated or regenerated activated carbons. 5.5 Fig. 1 shows the adsorbate concentration profile in an activated carbon bed at breakthrough. The bed has a zone at the inlet in which the adsorbate concentration is equal to the influent concentration. In this region the carbon is at equilibrium with adsorbate. The adsorbate concentration in the remainder of the bed drops until at the outlet it is equal to the breakthrough concentration. The shorter the length of this mass transfer zone (adsorption zone), the more effectively the carbon in the bed is utilized. A bed whose depth is less than the length of this zone will show immediate appearance of adsorbate in the effluent (breakpoint). FIG. 1 Concentration Profile of an Activated Carbon Bed at Breakthrough 5.6 From the standpoint of best carbon utilization it is desirable to choose a carbon which will give as short a mass transfer zone as possible under use conditions. However, in many applications, high adsorptive capacity is more important than a short mass transfer zone. In almost every application, bed pressure drop is also a primary consideration. 5.7 In a few situations such as respiratory protection against low levels of extremely toxic gases such as radioactive methyl iodide, a short mass transfer zone (that is, high adsorption rate coefficient) is more important than ultimate capacity. In other cases such as solvent recovery, a high dynamic capacity is more important. 5.8 Although the design of adsorber beds is beyond the scope of this guide, the following points should be considered. The bed diameter s......

Standard Guide for Gas-Phase Adsorption Testing of Activated Carbon

ASTM D4641-94(2006) 由氮解吸等温线计算催化剂孔隙尺寸分布的标准实施规程

Pore volume distribution curves obtained from nitrogen sorption isotherms provide one of the best means of characterizing the pore structure in porous catalysts, provided that the limitations of the method are kept in mind. Used in conjunction with the BET treatment for surface area determination (4), these methods provide an indispensable means for studying the structure associated with pores usually important in catalysts. This practice is particularly useful in studying changes in a series of closely related samples caused by treatments, such as heat, compression, or extrusion often used in catalyst manufacturing. Pore volume distribution curves can often provide valuable information during mechanistic studies dealing with catalyst deactivation.1.1 This practice covers the calculation of pore size distributions for catalysts and catalyst carriers from nitrogen desorption isotherms. The computational procedure is particularly useful for determining how the pore volume is distributed in catalyst samples containing pores whose sizes range from approximately 1.5 to 100 nm (15 to 1000 ) in radius. It should be used with caution when applied to isotherms for samples containing pores both within this size range and pores larger than 100 nm (1000 ) in radius. In such instances the isotherms rise steeply near P/Po = 1 and the total pore volume cannot be well defined. The calculations should be begun at a point on the isotherm near saturation preferably in a region near P/Po = 0.99, establishing an upper limit on the pore size distribution range to be studied. Simplifications are necessary regarding pore shape. A cylindrical pore model is assumed, and the method treats the pores as non-intersecting, open-ended capillaries which are assumed to function independently of each other during the adsorption or desorption of nitrogen. Note 1 - This practice is designed primarily for manual computation and a few simplifications have been made for this purpose. For computer computation, the simplified expressions may be replaced by exact expressions.This standard does not purport to address all of the safety concerns, 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.

Standard Practice for Calculation of Pore Size Distributions of Catalysts from Nitrogen Desorption Isotherms

ASTM D4607-94(2011) 测定活性碳碘值的标准试验方法

The iodine number is a relative indicator of porosity in an activated carbon. It does not necessarily provide a measure of the carbon''s ability to absorb other species. Iodine number may be used as an approximation of surface area for some types of activated carbons (see Test Method ). However, it must be realized that any relationship between surface area and iodine number cannot be generalized. It varies with changes in carbon raw material, processing conditions, and pore volume distribution (see Definitions D2652). The presence of adsorbed volatiles, sulfur; and water extractables may affect the measured iodine number of an activated carbon. 1.1 This test method covers the determination of the relative activation level of unused or reactivated carbons by adsorption of iodine from aqueous solution. The amount of iodine absorbed (in milligrams) by 1 g of carbon using test conditions listed herein is called the iodine number. 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 This standard does not purport to address all of the safety concerns, 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 statements are given in Section 7.

Standard Test Method for Determination of Iodine Number of Activated Carbon

ASTM D4607-94(1999) 活性碳碘值测定的标准试验方法

1.1 This test method covers the determination of the relative activation level of unused or reactivated carbons by adsorption of iodine from aqueous solution. The amount of iodine absorbed (in milligrams) by 1 g of carbon using test conditions listed herein is called the iodine number. 1.2 This standard does not purport to address all of the safety concerns, 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 statements are given in Section 7.

Standard Test Method for Determination of Iodine Number of Activated Carbon

ASTM D4607-94(2006) 活性碳碘值测定的标准试验方法

The iodine number is a relative indicator of porosity in an activated carbon. It does not necessarily provide a measure of the carbonrsquo; ability to absorb other species. Iodine number may be used as an approximation of surface area for some types of activated carbons (see Test Method C 819). However, it must be realized that any relationship between surface area and iodine number cannot be generalized. It varies with changes in carbon raw material, processing conditions, and pore volume distribution (see Definitions D 2652). The presence of adsorbed volatiles, sulfur; and water extractables may affect the measured iodine number of an activated carbon. 1.1 This test method covers the determination of the relative activation level of unused or reactivated carbons by adsorption of iodine from aqueous solution. The amount of iodine absorbed (in milligrams) by 1 g of carbon using test conditions listed herein is called the iodine number.1.2 This standard does not purport to address all of the safety concerns, 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 statements are given in Section 7.

Standard Test Method for Determination of Iodine Number of Activated Carbon

ASTM D2866-94(2004) 活性碳的总灰分含量的标准试验方法

In specific end uses, the amount and composition of the ash may influence the capabilities and certain desired properties of activated carbon. 1.1 This test method describes a procedure for the determination of total ash content of activated carbon.1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and deterrmine the applicability of regulatory limitations prior to use.

Standard Test Method for Total Ash Content of Activated Carbon

ASTM D5542-94(1999)e1 使用离子色谱法测定高纯度水中痕量阴离子的标准试验方法

1.1 These test methods cover the determination of trace ([mu]g/L) levels of fluoride, acetate, formate, chloride, phosphate, and sulfate in high purity water using ion chromatography in combination with sample preconcentration. Other anions, such as bromide, nitrite, nitrate, sulfite, and iodide can be determined by this method. However, since they are rarely present in significant concentrations in high purity water, they are not included in this test method. Two test methods are presented and their ranges of application, as determined by a collaborative study, are as follows: 1.2 It is the user''s responsibility to ensure the validity of these test methods for waters of untested matrices. 1.3 The common practical range of Test Method A is as follows: chloride, 1 to 100 [mu]g/L, phosphate, 3 to 100 [mu]g/L, and sulfate, 2 to 100 [mu]g/L. 1.4 The common practical range of Test Method B is as follows: fluoride, 1 to 100 [mu]g/L, acetate, 10 to 200 [mu]g/L, and formate, 5 to 200 [mu]g/L. 1.5 The values stated in SI units are to be regarded as the standard. 1.6 This standard does not purport to address all of the safety concerns, 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.

Standard Test Methods for Trace Anions in High Purity Water by Ion Chromatography

ASTM D4641-94(1999)e1 由氮解吸等温线计算催化剂孔隙尺寸分布的标准实施规程

1.1 This practice covers the calculation of pore size distributions for catalysts and catalyst carriers from nitrogen desorption isotherms. The computational procedure is particularly useful for determining how the pore volume is distributed in catalyst samples containing pores whose sizes range from approximately 15 to 1000 \A (10 \A-1 nm) in radius. It should be used with caution when applied to isotherms for samples containing pores both within this size range and pores larger than 1000 \A in radius. In such instances the isotherms rise steeply near / Po = 1 and the total pore volume cannot be well defined. The calculations should be begun at a point on the isotherm near saturation preferably in a region near / Po = 0.99, establishing an upper limit on the pore size distribution range to be studied. Simplifications are necessary regarding pore shape. A cylindrical pore model is assumed, and the method treats the pores as non-intersecting, open-ended capillaries which are assumed to function independently of each other during the adsorption or desorption of nitrogen. Note 1-This practice is designed primarily for manual computation and a few simplifications have been made for this purpose. For computer computation the simplified expressions may be replaced by exact expressions. 1.2 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.

Standard Practice for Calculation of Pore Size Distributions of Catalysts from Nitrogen Desorption Isotherms