Steam Reforming of Tar Derived from Walnut Shell and Almond Shell Gasification on Red Mud and Iron-Ceria Catalysts

Catalytic steam gasification of shells (almond and walnut) was carried out in a flow-type double-bed microreactor. Temperature-programmed thermal steam gasification of shells was performed at 200-850 degrees C, followed by the catalytic gasification of volatiles (including tar) at different temperatures. The iron-ceria catalyst and red mud (as the iron oxide catalyst) were used as a catalytic bed material. Effects of the catalyst on tar decomposition and tar gasification were investigated. The iron-ceria catalyst enhanced both tar degradation and hydrogen production via the water-gas shift reaction. The tar conversions of 94% (for almond shell) and 100% (for walnut shell) were achieved at a very low temperature (600 degrees C). The red mud was found less active in tar decomposition because of the inhibition of sodium aluminum silicate hydrate to the activity of iron oxide.