High-temperature solar heat, created by solar concentrator, can drive thermochemical splitting of CO2. The chemical process normally consists of two step reaction: reduction of reactive material to release O2 at the high temperature beyond 1200 ℃ and oxidation of the material in the presence of CO2 at the relatively low temperature below 1200 ℃. The overall reaction corresponds to decomposition of CO2 to (1/2) O2 and CO. This study conducted experiment of thermochemical CO2 splitting using vertical tubular furnace with ceria foam device and system analysis for demonstration and commercial plant. The experiment revealed that the generation of CO became 50 % larger as the temperature at reduction increases from 1500 ℃ to 1600 ℃. Also, it was revealed that the effects from temperature at oxidation is not essential when the temperature is 1000 ℃ or higher. The highest level of generation of CO reached 7.0 mL/gceria at 1600 ℃ of reduction temperature. As to the gas concentration, percentage of CO increased to 45 % when the experiment used three pieces of the foam device with micropore which total weight was 145.63 g. The experimental result was compared with and was found to agree with the equilibrium theory where the partial pressure of oxygen at the reduction step was assigned at 1.0 x 10-4 atm. This quantity was cited at the numerical condition for the system analysis of demonstration plant. The analysis indicated that the overall efficiency from solar to the combustion heat of CO can be higher than 10 % with the recuperation of exhaust heat of released gas and reactive material.

Masashi Suzuki

Mr.