In a significant stride towards enhancing biomass chemical looping gasification (BCLG), researchers have unveiled a novel approach to improve the performance of oxygen carriers, potentially revolutionizing the energy sector’s green transition. The study, led by Haochen Sun from Tampere University in Finland, focuses on the pivotal role of nickel (Ni) doping in ilmenite, an abundant and cost-effective mineral, to boost oxygen release and inhibit phase segregation during the chemical looping process.
BCLG has emerged as a promising technology for green energy production, offering a cleaner alternative to traditional methods. However, challenges such as methane (CH4) and tar generation have hindered its commercialization. Sun and his team addressed these issues by developing a Ni-modified ilmenite oxygen carrier, significantly reducing CH4 content and increasing syngas generation.
The researchers screened several industrial wastes for their syngas and CH4 reactivity, finding that ilmenite exhibited excellent syngas selectivity and potential reactivity with CH4. However, the reaction proceeded slowly due to the phase transformation process of TiFe2O5 – TiFeO3 – Fe, which is the rate-limiting step. To overcome this, the team applied various metallic dopants, including Ni, Co, and Ca, to reinforce ilmenite’s CH4 reactivity.
“Interestingly, Ni exhibited a higher promoting effect than Ca, whereas Co had little promotion on ilmenite reactivity,” Sun explained. The superior performance of Ni doping was attributed to the incorporation of Ni2+ in the Fe-O-Ti structure, rather than Ni0. This was validated through pre-activation and cyclic experiments, as well as density functional theory calculations.
The modulated electronic structure by Ni2+ in the Fe-O-Ti lattice significantly enhanced oxygen release capacity and Fe/Ti interactions. This activation of ilmenite’s reactivity with CH4 suppressed Ti/Fe phase segregation, making the as-prepared 5Ni-ilmenite a promising cost-effective oxygen carrier for high-quality syngas production in BCLG.
The implications of this research are substantial for the energy sector. By improving the efficiency and reducing the costs of BCLG, this innovation could accelerate the adoption of cleaner energy technologies, contributing to global efforts to tackle climate change. As Sun noted, “This study not only advances our understanding of oxygen carriers in chemical looping processes but also opens up new possibilities for utilizing industrial wastes in green energy production.”
Published in the journal *Carbon Capture Science and Technology*, this research highlights the potential of Ni-doped ilmenite to enhance the performance of chemical looping gasification, paving the way for more sustainable and efficient energy solutions. The findings could inspire further developments in the field, driving innovation and shaping the future of green energy technologies.