Diffusion Coefficient in Heteropoly Acid Catalyst Measured by Piezoelectric Quartz Crystal Microbalance

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN

Hiroo Niiyama²  Noriko Sugiura¹  Taku Utada¹  Ryuichi Nakamura¹ 

[1] Department of Chemical Engineering, Tokyo Institute of Technology;International Cooperation Center for Science and Technology, Tokyo Institute of Technology

关键词: Mass Transfer;    Diffusion Coefficient;    Quartz Crystal Microbalance;    Mass Loading Effect;    Heteropoly Acid;    12-Tungstophosphoric Acid;    Pseudo-Liquid Phase;    Catalysis;    Isotope Replacement;    Molecular Selective Sensor;   

DOI  :  10.1252/jcej.24.417

来源: Maruzen Company Ltd

【 摘 要 】

References(17)Cited-By(1)A piezoelectric quartz crystal microbalance was used to measure the diffusion coefficient of water in 12-tungstophosphoric acid catalyst. The catalyst was coated on the electrode surface of the quartz resonator and the time course of weight change caused by sorption/desorption could be followed in the nanogram range by measuring the frequency change. It was found that the diffusion rate increased with concentration of water absorbed and the response curve was successfully analyzed by assuming a diffusion coefficient as a function of concentration. This concentration dependency indicates that the diffusion process of water in a heteropoly acid is affected by the interaction with active sites. Isotope replacement studies using the same detection method revealed that the concentration dependency of diffusion coefficient disappeared. The obtained values of diffusion coefficients showed the same order as that by the unsteady method and lay in a reasonable order of magnitude.

【 授权许可】

Unknown