Determination method of angstrom pore size distribution with molecular statistical method

用高分辨分子吸附技术研究了非晶碳的微孔结构。特别是对超微孔结构进行了详细的研究。利用激光探测器，从超高真空度和高灵敏度的重量变化系统中建立了一套新的吸附装置，在10^~(-9)~1的较宽的相对压力范围内测量了氮气和Ar的吸附等温线。该宽压吸附装置可以测量77K下均匀超微孔碳的氮吸附等温线。我们正在尝试发展一种新的理论来分析这些宽压范围的吸附等温线。利用高分辨率氮气吸附等温线，得到了77K下的微孔孔径分布。用密度泛函方法可以得到0.5~几nm的微孔尺寸分布。并用宏正则蒙特卡罗模拟(GCMC)模拟了77K下氮化吸附等温线对活性碳纤维微孔尺寸分布的影响，但权函数的选取对孔径分布的影响很大，因此需要改进。用水蒸气吸附法测定了微孔体积。将303K下的实验吸附等温线与GCMC模拟的吸附等温线进行比较，得到了准确的超微孔尺寸。该方法可测定超微孔尺寸，测量精度可达0.02 nm。

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.