Tunable syngas production from biomass: Synergistic effect of steam, Ni–CaO catalyst, and biochar

The production of tunable syngas from biomass will further establish the role of biomass-derived syngas as a versatile platform for liquid fuels and value-added chemical synthesis. This study introduced steam, Ni–CaO catalyst, and biochar into a proposed two-stage sorption-enhanced catalytical thermochemical conversion process, aiming to obtain the tunable syngas through the in-situ stepwise generation of high purity H₂ and CO. The presence of steam and Ni–CaO catalyst shows unprecedented performance in enhancing the H₂ generation due to the promotional tar steam reforming/cracking and water-gas shift reactions at the first stage, and the control experiments indicate that the steam performs a higher selectivity to H₂ than the Ni–CaO catalyst. The introduction of biochar with a supplementary carbon source, remarkably promotes the CO generation at the second stage, which could be further pronounced by the addition of Ni–CaO catalyst. A synergistic effect of steam, Ni–CaO catalyst, and biochar contributes to a significant enhancement in H₂ and CO generation with an inherently separated generation of H₂ (88.2 ± 2.3 vol% of purity) and CO (55.6 ± 1.3 vol% of purity). And the combined use of steam, Ni–CaO catalyst, and biochar could lead to a superior syngas quality with high LHV_syngas and energy recovery efficiency.