Suppression of carbon formation in steam reforming of methane by addition of Co into Ni/ZrO₂ catalysts

We investigated the steam reforming of methane (SRM) over various NiCo bimetallic catalysts supported on ZrO₂ to determine whether the addition of Co on the Ni catalyst suppressed carbon formation. The effect of metal loading on SRM reaction was evaluated in a downflow tubular fixed-bed reactor under various steam-to-carbon (S/C) ratios and temperatures. For monitoring changes in the catalysts before and after the SRM reactions, several techniques (BET, XRD, TEM, and CHN analysis) were used. The effects of reaction temperature, gas hourly space velocity (GHSV), and molar S/C ratios were studied in detail over the various catalyst combinations. It was found that an Ni- to-Co ratio of 50: 50 supported on ZrO₂ provided the best catalytic activity, along with an absence of coking, when operated at a temperature of 1,073 K, a GHSV of 24 L g^-1 h^-1, and an S/C ratio of 3: 1.