Simultaneous Coke Reduction with Improved Syngas Production during Propane Steam Reforming using Forced CO2 Cycling

Abstract

Carbon deposition during hydrocarbon steam reforming is often a major cause of pathological reactor performance and catalyst deactivation. In this paper, we report the effect of forced periodic cycling between propane-steam reforming feed and a carbon gasifying agent (CO2) as a novel reactor strategy to both improve product yield (H2 and CO) and catalyst longevity. Experiments were carried out over Co-Ni/Al2O3 catalyst in a fluidized bed reactor. Cycle period, ?, was varied between 5 to 20 mins at 5 different cycle splits, (0.1 ? s ? 0.9). Both H2 and CO formation rates were higher (up to 5-fold and more than 10-fold, respectively) than that attainable under steady-state operation at all periods investigated. In particular, the time-average H2:CO ratio was lower (< 3.0) than the steady-state equivalent for the pure propane steam reforming (14.0), although it increased monotonically with cycle split. Composition cycling with CO2 also improved catalyst stability and longevity compared to steady-state performance at the cycle periods examined. This strategic reactor operation is therefore a potentially useful key to green process engineering in the overall petrochemical plant design to effect greenhouse gas emission reduction.