New insight and countermeasure for sulfur poisoning on nickel-based catalysts during dry reforming of methane.

[Display omitted] • A mechanism for sulfur poisoning the Ni/Al 2 O 3 catalyst was proposed. • The main factor accelerating catalyst poisoning is the migration of elemental S. • The catalyst adding 1.0% SiO 2 exhibits improved sulfur tolerance. • Smaller Ni particles are more sulfur-tolerant than larger ones. Dry reforming of methane (DRM) is the method to convert two greenhouse gases to synthesis gas. The nickel-based catalysts used in the DRM are extremely easily poisoned by H 2 S in the feed gas, however, the associated poisoning process is not clear. In this work, a mechanism for poisoning the Ni/Al 2 O 3 catalyst by elemental sulfur migration was proposed, and silica was added to the catalyst to prolong the sulfur tolerance of the catalyst. From the characterizations of the catalyst with different methods, it was noted that the main factor accelerating catalyst poisoning was the formation and migration of elemental sulfur. The catalyst Ni/Al 2 O 3 with 1.0 % SiO 2 exhibited improved sulfur tolerance. The addition of SiO 2 inhibits the growth of Ni particles during the reduction process, and the smaller Ni particles lead to less coke and a longer period of sulfur tolerance. [ABSTRACT FROM AUTHOR]