Abstract
A transient response method using the isotope replacement technique was used to verify “pseudo-liquid phase” behavior of 12-tungstophosphoric acid and to investigate the solubility and mobility of polar substances such as alcohols and ethers. The relationship between the concentration of labeled molecules in gas phase and that in bulk phase can reasonably be assumed as linear in this technique, regardless of intrinsic non-linear relationships of diffusion and absorption. It was found that the polar molecules can be absorbed into the bulk phase of catalyst under these experimental conditions. The small values of effective diffusivities, which are on the order of 10–10 m2s–1, are observed to be close to that in liquid-filled pores. The amount of absorbed molecules of alcohols, determined by polarity, tend to have a unique stoichiometry corresponding to the number of protons in H3PW12O40, and the mobility depends on either polarity or molecular size.
