CHARACTERIZATION OF POROUS SOLIDS BY NMR

A new simple and rapid method to determine pore size distributions is described which employs a simple nuclear magnetic resonance (NMR) appa ratus. The method exploits the depression of the melting point of a cr ystalline solid confined within a pore, which is dependent on the pore diameter. The melting point distribution is determined by analyzing t he NMR signal as a function of temperature. The technique is demonstra ted by application to porous silicas and is shown to give pore size di stributions comparable to those obtained by the conventional gas desor ption method for pore sizes in the range 5 to 50 nm.