Ateş, Ayten2022-05-112022-05-116 Januaryhttps://www.sciencedirect.com/science/article/pii/S0360319920338696https://hdl.handle.net/20.500.12418/12757TiO2 samples with different crystal sizes and compositions were synthesized using a sol-gel method at different calcination temperatures (350–900 °C). The activity and stability of TiO2 samples were determined by the gasification of formaldehyde in supercritical water (SCW) and by treatment in SCW. Increasing calcination temperature and SCW gasification (SCWG)/SCW treatment decreased the surface area of anatase TiO2 samples due to growing crystallite size via agglomeration and sintering. Among anatase TiO2 samples, the TiO2 calcinated at 450 °C was found as the most suitable material under SCW conditions. However, the surface area of rutile TiO2 slightly increased from 17.2 m2 g−1 to 19.8 m2 g−1 with the weakly crumbling of particles during SCWG. The highest hydrogen formation (63%) from formaldehyde in the SCW was obtained in the presence of anatase TiO2 calcined at 350 °C and rutile TiO2 calcined at 800 °C. CO2 formation in the presence of anatase TiO2 is higher than rutile TiO2 because of the presence of active lattice oxygen species (O−, O2−) based on O2-TPD.en10.1016/j.ijhydene.2020.10.072info:eu-repo/semantics/closedAccessStability; TiO2; Sol-gel; SCWG; FormaldehydeArticle462185618422-s2.0-85095757226N/AWOS:000605147300034Q2