First insights for hydrogen production using an alkaline ceramic through the water-gas shift reaction

Hydrogen production was successfully obtained and enriched using lithium cuprate (Li2CuO2) as a multifunctional material during the water-gas shift reaction (WGSR). For this propose, water vapor and carbon monoxide reacted consecutively (C-WGSR) or simultaneously (S-WGSR) over the Li2CuO2 particle surface. In both cases, Li2CuO2 functioned as a catalyst, producing H-2 and CO2 in a moderate temperature range (250-450 degrees C). In addition, lithium cuprate was able to capture the CO2 produced in WGSR, enhancing the H-2 purity in the final gas flow. When the consecutive procedure (C-WGSR, first water vapor and then CO) was employee, the best H-2 formation (75%) was obtained at around 250 degrees C. However, it was limited by the amount of H2O previously sorbed on Li2CuO2 surface, proceeding the reaction only in a short period of time (t < 1 min). In the second case S-WGSR, H2O vapor and CO were flowed simultaneously at 300 degrees C, resulting in lower amounts of H-2 (between 30 and 50 %) than in C-WGSR. However, hydrogen production was maintained for longer times (0 < t < 120 min), presenting an important advantage over the consecutive procedure. It must be mentioned that in S-WGSR, the CO2 chemisorption on the ceramic tended to diminish the H-2 production as Li2CuO2 produced through the capture process blocking the H2O sorption sites, although the CO continued being totally converted. Further cyclic experiments showed that it was possible to maintain H-2 formation during several consecutive cycles when lithium cuprate regeneration was performed under an oxygen flow at 700 degrees C. Finally, this work is the first experimental evidence that an alkaline ceramic can act as a functional material to produce a clean energy source, such as hydrogen through the WGSR process at low and moderate temperatures.