Authors: Ram Prasad, Suverna Trivedi
The deep oxidation of CO-CH4 mixture was investigated over NiCo2O4, K-NiCo2O4, Pd-NiCo2O4 and K-Pd- NiCo2O4 catalysts. The promoters doping in the spinel catalyst was optimized which revealed 2wt % K and 0.1 wt % Pd were the best compositions for the oxidation reaction. The catalysts were prepared by co-precipitation of basic carbonates of Ni and Co followed by doping of the promoters and reactive calcination in 4.5% CO-air environment. The catalysts were characterized by XRD, TPR, XPS, BET, and SEM-EDX. The oxidation of said mixture was performed in a fixed-bed-tubular-reactor under following conditions: 500mg catalyst, 1.5%CO, 1.5%CH4, 100ml/min. total gas flow-rate and at atmospheric pressure. The catalysts were highly selective for CO2 formation as no other byproduct of the oxidation reaction was detected under the conditions studied. The characterization demonstrated that doping of promoters improved the catalyst reducibility and changed redox properties, resulting in a higher catalytic performance. The performance of K-Pd-NiCo2O4 catalyst was the best for total oxidation of CO-CH4 mixture at ~320oC. The performance of K-doped catalyst (342oC) for the complete combustion of the mixture was within Pd-doped (335 oC) and undoped (350oC) catalysts. The activity order of the catalysts was as follows: K-Pd-NiCo2O4 > Pd-NiCo2O4 > K-NiCo2O4> NiCo2O4.
Keywords: CO-CH4 emissions; NiCo2O4 catalysts; K-Pd promoters; catalyst characterization; deep oxidation