The overall mass-transfer process of methane decomposition on Ni surfaces and hydrogen permeation through a Ni tube was experimentally investigated to design a catalytic-permeable Ni tube reactor. This is a basic study of an impurity detritiation system to decompose tritiated methane and continuously recover tritium in a gas mixture exhausted from fusion plasma. The mass-transfer process was comparatively studied under the two conditions of an open Ni tube without any packing and a Ni tube packed with 200-240 mesh Ni particles. Results were discussed in terms of a CH4 decomposition ratio ηdecomp and a H2 permeation ratio η perm. The ηdecomp values depended on temperature and were almost independent of the flow rate. The ηdecomp value was correlated to the first-order reaction-rate constant. On the contrary, the ηperm values were in reverse proportion to the flow rate and were almost independent of temperature. The ηperm value was related to diffusion through a H2 concentration boundary layer formed in the vicinity of the Ni tube wall. The degradation of catalytic performance due to carbon deposition on Ni was discussed based on our experiments.
All Science Journal Classification (ASJC) codes
- Civil and Structural Engineering
- Nuclear and High Energy Physics
- Nuclear Energy and Engineering
- General Materials Science
- Mechanical Engineering