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    What is pore size distribution measurement?

    作者:管理員       發布日期: 2015-08-12      點擊: 2902
         What is pore size distribution measurement? 

     For many fine powders, their surface is not smooth, some powder are designed that way on purpose. Pore size, shape and quantity strongly relate to its other properties, such as catalyst and adsorbent. So its important to measure pore volume, pore size distribution. Pore volume and pore size distribution are the change ratio of pore volume to pore size for different pore sizes. Normally pores are divided into three categories: micro-pore, size≤2nm; mid-pore, size 2-50nm; large-pore, size≥50nm, in which mid-pore is the main group.

        Nitrogen adsorption measurement method for mid- and micro-pores is a mature and popular technique. It is derived from BET surface area measurement by nitrogen adsorption method, both of which use nitrogen isotherm curves: at liquid nitrogen temperature, nitrogen adsorption volume on solid surface is determined by relative pressure(P/P0),P nitrogen partial pressure, P0 nitrogen saturation vapor pressure at liquid nitrogen temperature; when P/P0 is in the range of 0.05-0.35, adsorption behavior can be described by BET equation properly; when P/P0≥0.4, condensation will occur due to capillary, e.g. nitrogen starts to condense at pores, through experiments and theoretic analysis, pore volume and size can be obtained.

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