1.1 本规程包括根据氮气脱附等温线计算催化剂和催化剂载体的孔径分布。该计算程序对于确定孔径范围约为1.5至100 nm（15至1000Å）的孔在催化剂样品中的分布特别有用。当将其应用于含有该尺寸范围内的孔和半径大于100 nm（1000Å）的孔的样品的等温线时，应小心使用。在这种情况下，等温线在附近急剧上升 P / P o = 1和总孔隙体积无法很好地定义。计算应从等温线上接近饱和的点开始，最好是在接近饱和的区域 P / P o = 0.99，建立待研究孔径分布范围的上限。 有必要对孔隙形状进行简化。假设为圆柱形孔隙模型，该方法将孔隙视为非相交的开口毛细管，假设其在氮气吸附或解吸过程中相互独立发挥作用。 注1: 本实践主要用于手动计算，并为此进行了一些简化。对于计算机计算，可以用精确表达式代替简化表达式。 1.2 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.3 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全和健康实践，并确定监管限制的适用性。 ====意义和用途====== 5.1 从氮吸附等温线获得的孔体积分布曲线提供了表征多孔催化剂孔结构的最佳方法之一，前提是牢记该方法的局限性。与BET处理一起用于测定表面积 ( 5. ) 这些方法为研究通常在催化剂中很重要的孔的结构提供了不可或缺的手段。这种做法在研究由处理引起的一系列密切相关样品的变化时特别有用，例如催化剂制造中经常使用的加热、压缩或挤压。在处理催化剂失活的机理研究中，孔体积分布曲线通常可以提供有价值的信息。

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 Å) 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 Å) in radius. In such instances the isotherms rise steeply near P / P o = 1 and the total pore volume cannot be well defined. The calculations should begin at a point on the isotherm near saturation preferably in a region near P / P o = 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 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. ====== Significance And Use ====== 5.1 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 ( 5 ) , 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.