Go and Ni supported on CeO_2 as selective bimetallic catalyst for dry reforming of methane

摘要

Co/CeO_2 (Co 7.5 wt.%), Ni/CeO_2 (Ni 7.5 wt.%) and Co-Ni/CeO_2 (Co 3.75 wt.%, Ni 3.75 wt.%) catalysts were prepared by surfactant assisted co-precipitation method. Samples were characterized by X-Ray diffraction, BET surface areas measurements, temperature programmed reduction and tested for the dry reforming of methane CH_4 + CO_2 → 2CO + 2H_2 in the temperature range 600-800 ℃ with a CH_4:CO_2:Ar 20:20:60 vol.% feed mixture and a total flow rate of 50 cm~3 min~(-1) (GHSW = 30,000 mL g~(-1)h~(-1)). The bimetallic Co-Ni/CeO_2 catalyst showed higher CH_4 conversion in comparison with monometallic systems in the whole temperature range, being 50% at 600 ℃ and 97% at 800 ℃. H_2/CO selectivity decreased in the following order: Co-Ni/CeO_2 > Ni/CeO_2 > Co/CeO_2. Carbon deposition on spent catalysts was analyzed by thermal analysis (TG-DTA). After 20 h under stream at 750 ℃, cobalt-containing catalysts, Co/CeO_2 and Co-Ni/CeO_2, showed a stable operation in presence of a deposited amorphous carbon of 6 wt.%, whereas Ni/CeO_2 showed an 8% decrease of catalytic activity due to a massive presence of amorphous and graphitic carbon (25 wt.%).