AVS 53rd International Symposium
    Surface Science Thursday Sessions
       Session SS-ThP

Paper SS-ThP20
Purification of Otho-Hydrogen by Adsorption Separation Method Combined with Thermal Desorption Process

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: Surface Science Poster Session
Presenter: K. Niki, The University of Tokyo, Japan
Authors: K. Niki, The University of Tokyo, Japan
T. Kawauchi, The University of Tokyo, Japan
M. Matsumoto, The University of Tokyo, Japan
K. Fukutani, The University of Tokyo, Japan
T. Okano, The University of Tokyo, Japan
Correspondent: Click to Email
Separation of ortho-hydrogen from normal hydrogen, a mixture of ortho H@sub 2@ (o-H@sub 2@) and para-H2 (p-H@sub 2@), has been carried out by using an adsorption separation method, which exploits the difference between the activation energies of desorption of o-H@sub 2@ and p-H@sub 2@. @footnote 1@ The optimum value of the separation coefficient S was empirically determined and analyzed based on adsorption equilibrium data of o-H@sub 2@ and p-H@sub 2@. Recently, we developed rotational state-selective thermal desorption spectroscopy (TDS) for hydrogen molecules. Grains of activated alumina were contained in a sample cell attached to the cold head of a mechanical refrigerator. After the activated alumina was exposed to normal hydrogen for a certain time, it was heated at a constant rate. The desorbing hydrogen molecules were ionized from selected rotational quantum status by resonant-enhanced multiphoton ionization (REMPI). The TDS peak temperatures were measured as 18K and 16 K for o-H@sub 2@ and p-H@sub 2@, respectively. In previous reports on the adsorption separation process, the molecular process during the desorption period was not well-analyzed. Based on our state-selective TDS data, we calculated the enhancement of the separation coefficient by sampling the desorbing hydrogen molecules at an intermediate temperature during the TDS measurement. To prove this estimation of the enhancement of the separation coefficient, we constructed an o-H@sub 2@ purifier. The apparatus consists of two parts: an adsorption separation cell system and a REMPI detector system. Details of the experimental results of o-H@sub 2@ purification and the comparison with the calculation is to be presented. @FootnoteText@ @footnote 1@ C. M. Cunningham et al., J. Am. Chem. Soc. 80, 2382 (1957).