Fe and CaO promoted Ni catalyst on gasifier bed material for tar removal from producer gas

A new Ni-based mixed oxide material (Ni-Fe-CaO) for catalyzing Carbo HSP gasifier bed material was prepared and characterized by XRD, TPR, TEM, and SEM techniques. The catalyst performance for tar removal from a simulated producer gas mixture via steam reforming was tested in a laboratory-scale fixed-bed reactor between 700 and 800 degrees C, using toluene and ethylene as tar surrogates. Ni-Fe-CaO catalysts had significantly higher activity and deactivation resistance for toluene removal compared to either Ni-Fe or Ni catalysts. Keeping CaO loading similar in the catalysts, the Ni:Fe ratio was varied and the optimum tar conversion and highest COx selectivity were obtained with ratios of 3:1 and 2:1. The turn over frequency (TOF) on Ni in the Ni-Fe-CaO mixed oxides were higher compared to pure Ni or Ni-CaO combinations and increased with lowering Ni/Fe ratio. High tar removal activity (80% vs 68%) and COx selectivity (96% vs 98%) at 750 degrees C were obtained for 1.6% (Ni45Fe15Ca40)/Carbo HSP and 1.6% (Ni40Fe20Ca40)/Carbo HSP compositions, respectively. Deactivation occurred mainly due to sintering of the 1.6% (Ni45Fe15Ca40) composition reducing conversion efficiency by 17% (from 99.7% to 83%) after 48 h in time-on-stream at 800 degrees C. After regeneration with a O-2/H-2 sequence, the conversion was reduced from 98% to 80% after 24 h in time-on-stream. Similarly, 1.6% (Ni40Fe20Ca40) composition shows a stable conversion of similar to 80% at the end of 50 h, which was much superior compared to the 1% (Ni65Fe35)/Carbo HSP catalyst. The individual role of Fe and CaO in promoting Ni for improving catalytic activity and stability in Ni-Fe-CaO was investigated (C) 2015 Elsevier B.V. All rights reserved.