Preparation of Ni-based catalyst from incineration bottom ash for steam reforming of toluene as a model tar compound

Abstract

Ni-based catalysts are anticipated to emerge as the promising candidates for the reforming of biomass tar, owing to their commendable combination of high activity and low cost. However, waste-derived Ni-based catalysts exhibit inadequate stability in high-temperature reactions due to the sintering of catalyst. In this work, therefore, CaO was extracted from municipal solid waste (MSW) incineration bottom ash (IBA) as the support and the slag was prepared by melting the residues (molten slag, MS) as an inert stabilizer to enhanced the stability of catalysts. Toluene was chosen as the model compound for biomass tar to evaluate the performance of IBA-derived Ni-based catalyst in the steam reforming process. The toluene conversion of catalysts exhibited a volcano-type variation as the MS addition increased from 5 % to 20 %. Ni/MS15Ca85 exhibited excellent activity (83.87 %) at 850 °C, steam-to-carbon ratio (S/C) of 3, and gas hourly space velocity (GHSV) of 23040 h−1, and displayed no significant deactivation after 24 h (GHSV of 45700 h−1). The introduction of MS promoted the reduction of NiO, which improved the catalyst activity by forming the Ni-rich Ni-Fe alloy. Meanwhile, MS promoted the increase of lattice oxygen species (OL) content to enhance the oxidation of carbon. Furthermore, Ca2SiO4 and Ca12Al14O33 formed by the reaction of SiO2 and Al2O3 in MS with CaO contributed to mitigating the aggregation of CaO particles and maintaining the porous structure of catalysts. This work provides a novel approach to improve the catalytic performance of IBA-derived Ni-based catalyst for steam reforming of toluene (SRT) by realizing the precise regulation of each component in IBA and elimination of secondary residue disposal that was rarely considered in previous studies.