Impact of Promoter Addition on the Regeneration of Ni/Al<sub>2</sub>O<sub>3</sub> Dry Reforming Catalysts
Robert Franz, Donato Pinto, Evgeny A. Uslamin, Atsushi Urakawa, Evgeny A. Pidko
Abstract
Abstract Industrial‐scale reforming of methane is typically carried out with an excess of oxidant to suppress coking of the catalyst. On the other hand, many academic studies on dry reforming employ a CO 2 /CH 4 ratio of unity to quickly observe coking which can be reduced by adding a catalyst promoter. In this work, Ni/Al 2 O 3 catalysts were tested for dry reforming of methane (CO 2 /CH 4 =1) with additional regeneration steps to test the resistance against an oxidation treatment. Thereby, we wanted to evaluate catalyst stability for industrial relevance. The effects of three promoters, Cr, Mn and Fe, that differ in their degree of CO 2 interaction, are compared. A higher iron loading on Ni/Al 2 O 3 leads to higher stability in dry reforming with lower coke formation. However, the higher the concentration of a promoter with high CO 2 affinity, the quicker the catalyst is oxidized during regeneration with CO 2 . Subsequent reduction of a catalyst oxidized with CO 2 leads to considerable sintering in all cases. This sintering induces formation of more coke during dry reforming. On such sintered samples only highly effective promoters in large concentrations still have a noticeable effect compared to unpromoted Ni/Al 2 O 3 .