Determination method of angstrom pore size distribution with molecular statistical method

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The micropore structures of noncrystalline carbons were examined by high resolution molecular adsorption. In particular ultramicropore-range structures were studied carefully. The nitrogen and argon adsorption isotherms were measured over a wide relative pressure range of 10^<-9> to 1 by construction of a new adsorption equipment from ultrahigh vacuum level and high sensitive weight change system with the aid of a laser detector. This wide pressure adsorption equipment can measure the nitrogen adsorption isotherm of even ultramicroporous carbon at 77 K.We are trying to develop a new theory for analysis of these wide pressure range adsorption isotherms.A new analytical method of a density functional theory (DFT) for calculation. of the micropore size distribution of activated carbon from the high resolution nitrogen adsorption isotherms at 77 K was developed. The DFT can give the micropore size distribution from 0.5 to several nm. Also grand canonical Monte Carlo simulation (GCMC) simulation was applied to determine the micropore size distribution of activated carbon fiber using nitroged adsorption isotherm at 77 K.In this case, the selection of the weight function still gave a serious influence on the pore size distribution and thereby the method must be improved.The nitrogen and argon adsorption isotherms at 303 K was used for determination of ultramicropores of molecular sieve carbons with the aid of GCMC simulation. The micropore volume was determined by water vapor adsorption. The comparison of the experimental adsorption isotherm at 303 K with the GCMC simulated isotherm provides the exact ultramicropore size. This method can determine the ultramicropore size with the accuracy of 0.02 nm.