CO methanation over TiO2-supported nickel catalysts: A carbon formation study

[Display omitted] •A carbon formation study was performed on titania-supported nickel catalysts.•The rate of carbon formation decreases with increasing syngas partial pressure.•Carbon formation increases with increasing temperature.•Water reduces the rate of carbon formation but accelerates catalyst deactivation.•Water can lead to a progressive destruction of strong metal-support interactions. A systematic study on titania-supported nickel catalysts was performed in order to evaluate the effect of different process conditions on catalyst stability. Reaction tests and temperature-programmed-hydrogenation analyses were used in order to evaluate the effect of temperature, feed composition, water and reduction conditions on catalyst deactivation and carbon deposition. It was shown that high H2/CO ratios and syngas partial pressures decrease the rate of carbon formation. Moreover, increasing temperature enhanced the formation of more stable carbon species and thus catalyst deactivation. The temperature-programmed hydrogenation analyses also revealed that water reduces the rate of carbon deposition. However, water enhanced catalyst deactivation when the catalysts were reduced at high temperatures. This negative effect of water is probably due to a progressive destruction of the strong-metal-support interaction characteristic of titania-supported nickel catalysts reduced at high temperatures.