(278b) Chemical Looping for Low Carbon Energy and Chemical Production

The high thermodynamic efficiency and inherent gas separation enabled by the chemical looping strategy offer significant opportunities for decarbonization of energy and chemical production. Historically, chemical looping research has focused on fossil fuel combustion, allowing for easy CO₂ capture and sequestration. In the past few years, we have studied chemical looping for a wide variety of chemical and energy production/conversion applications. For example, we have previously shown that chemical looping-based oxidative dehydrogenation can offer a 62 - 87% reduction in carbon emissions for the production of ethylene due to the high exergy efficiency and high single pass ethane conversions. In this work, we focus on two chemical looping pathways for decarbonization: Chemical Looping Air Separation (CLAS) and Chemical Looping H₂O/CO₂ Splitting. In CLAS, a mixed metal oxide is cyclically reduced in steam to give off gaseous oxygen and then oxidized in air to regenerate the oxide. We have shown that small-scale systems have the potential to produce oxygen at costs and energy demands comparable to or lower than large cryogenic air separation plants, greatly reducing parasitic losses for oxycombustion relative to pressure swing adsorption.

In chemical looping H₂O/CO₂ splitting, the mixed metal oxide catalyst is reduced by a fuel-rich gas stream and subsequently used to split either water into hydrogen or CO₂ into CO. This results in high-purity CO or H₂ without the use of extensive syngas conditioning and gas separation, allowing the production of low-cost hydrogen or conversion of captured CO₂ into a valuable chemical precursor. The fuel source for the reduction step can either be natural gas, which will produce high-quality syngas with a 2:1 H₂ to CO ratio, or an inexpensive, low-quality fuel gas stream from an industrial process. We present a detailed techno-economic analysis (TEA) and carbon emissions analysis of a system for the production of acetic acid from natural gas and CO₂. The potential integration of renewable energy to achieve negative net emissions of CO₂ is also discussed.