Direct reduction of iron oxides based on steam reforming of bio-oil : a highly efficient approach for production of DRI from bio-oil and iron ores

Production of direct reduced iron (DRI) was performed by a novel and environmentally friendly approach through a systematic experimental process development and process integration study on bio-oil reforming and iron ores reduction. The Ni-Cu-Zn-Al₂O₃ catalyst is one of most suitable candidates for bio-oil reforming because this non-noble metal catalyst can efficiently reform the bio-oil to H₂ and CO₂ at a lower operating temperature (450-500 °C) with a longer lifetime. The catalytic activities of the Ni-Cu-Zn-Al₂O₃ catalyst for different processes, including the reforming of the oxygenated organic compounds in the bio-oil, the water-gas shift reaction and the decomposition of organic compounds, have been investigated. A hydrogen yield of 87.4% with a carbon conversion of 91.8% was obtained at T = 500 °C and S/C = 6.1. The hydrogen content reached about 94.6 vol% after simple purification by removing CO₂. Furthermore, direct reduction of iron oxides at different reduction temperatures was investigated using on-line rich-hydrogen reducing gases. The metallization for production of DRI from three ore powders (limonite, hematite and magnetite) and hematite pellets ranges from 93 to 97% at 850 °C for 1 h reduction. The reduction process from the oxidized iron to metallic iron and the intermediate phases were investigated via chemical analysis, X-ray diffraction and X-ray fluorescence analyses. The green DRI process with high reduction efficiency and real environmental benefits would, potentially, be a useful route to produce DRI from bio-oil or biomass.12 page(s

High efficient production of hydrogen from crude bio-oil via an integrative process between gasification and current-enhanced catalytic steam reforming

High efficient production of hydrogen from the crude bio-oil was performed in the gasification-reforming dual beds. A recently developed electrochemical catalytic reforming method was applied in the downstream reforming bed using NiCuZnAl catalyst. Production of hydrogen from the crude bio-oil through both the single gasification and integrative gasification-reforming processes was investigated. The maximum hydrogen yield of 81.4% with carbon conversion of 87.6% was obtained through the integrative process. Hydrogen is a major product (∼73 vol%) together with by-products of CO₂ (∼26 vol%) as well as very low content of CO (<1%) and a trace amount of CH₄ through the integrative route. In particular, the deactivation of the catalyst was significantly depressed by using the integrative gasification-reforming method, comparing to the direct reforming of the crude bio-oil. The mechanism and evaluation for the downstream electrochemical catalytic reforming were also discussed. The integrative process with higher hydrogen yield and carbon conversion, potentially, would be a useful route to produce hydrogen from the crude bio-oil.15 page(s

High efficient production of hydrogen from bio-oil using low-temperature electrochemical catalytic reforming approach over NiCuZn-Al₂O₃ catalyst

High-efficient production of hydrogen from bio-oil was performed by a novel electrochemical catalytic reforming method over the NiCuZn-Al₂O₃catalyst. The influences of current on the hydrogen yield, carbon conversion and products' distribution were investigated. Both the hydrogen yield and carbon conversion were remarkably enhanced by the current through the catalyst, reaching nearly complete conversion with a hydrogen yield of 93.5% even at low reforming temperature of 400 °C. The thermal electrons would play important roles in promoting the reforming reactions of the oxygenated-organic compounds in bio-oil, molecular dissociation and the catalyst reduction.11 page(s