Preparation and evaluation of sol-gel made nickel catalysts for carbon dioxide reforming of methane

Abstract

Sol-gel (solution-gelation) method was used to prepare Ni-Ti and Ni-Ti-Al catalysts for reforming of methane with carbon dioxide. This method, after optimizing the parameters such as hydrolysis and acid/alkoxide ratio, is able to make a Ni-Ti catalyst with a surface area as high as 426m2/g when calcined at 473K; but calcination at higher temperature lead to dramatic decrease in surface area. XRD, XPS, TEM and SEM were used to understand this change.

Using a packed bed reactor, the catalysts were evaluated with the reforming reaction. It was found that the activity of the Ni-Ti catalyst increases with the Ni loading in the range of 1-10wt%. The reduction temperature has strong effect on activity of the reduced catalyst. Up to 973K, the activity increases with the reduction temperature; but after 973K, the activity decreases and become 0 when the temperature is over 1023K. The Ni-Ti catalyst also deactivated as 15% after 4h of time on stream. The XRD analysis shows that Ti3O5 formed in the catalyst after higher-temperature reduction as well as after the reaction for a period of time. The formation of Ti3O5 may render the catalyst to loss its activity. However, further study is expected to understand the mechanism. TG/DTA analysis shows that both Ni-Ti and Ni-Ti-Al catalysts had carbon deposition; but the latter maintained higher activity in a longer period of time.