Solar Reactor Demonstration of Efficient and Selective Syngas Production via Chemical‐Looping Dry Reforming of Methane over Ceria

Abstract

Technologies that facilitate the conversion of CH4 and/or CO2 with concentrated sunlight provide a viable strategy for storing solar energy in the form of liquid fuels and reducing anthropogenic greenhouse gas emissions. Herein, a scalable prototype receiver‐reactor is developed to experimentally demonstrate the chemical‐looping, dry reforming of methane over ceria with simulated concentrated solar radiation. Optimal operating conditions are identified by investigating wide ranges of parameters like temperature, gas flowrate, inlet CH4 concentration, initial oxygen nonstoichiometry, and particle size. Ultimately, a selectivity to H2 and CO of greater than 0.93 is observed at reactant conversions of 0.69 and 0.88 for CH4 and CO2, respectively. As a result, the calorific value of the products relative to the reactants is upgraded, and a solar‐to‐fuel conversion efficiency of 10.06% is attained, higher than the previously reported record of 7%. Near‐perfect selectivity to syngas is achieved by operating with low reactant residence times, and if reactions were initiated over oxygen‐deficient ceria. Reactant conversion is enhanced through a reduction in particle size, which enables more rapid kinetics via an increase in surface oxygen availability. Stable performance is demonstrated over 10 consecutive redox cycles under conditions that maximized efficiency for the system presented herein.

High-Purity and Clean Syngas and Hydrogen Production From Two-Step CH4 Reforming and H2O Splitting Through Isothermal Ceria Redox Cycle Using Concentrated Sunlight

“…This is because the rate of CH 4 supply was higher than the rate of oxygen discharged by ceria reduction reaction. The X CH4 values reported here were comparable with those of previous studies [16−44% (Warren et al, 2020) and 13-60% (Krenzke et al, 2016)]. In addition, X CH4 was found to be dependent on the inlet methane flow rate.…”

“…Warren et al (2017) investigated the cycle thermodynamics in comparison with the experimental investigation of the partial oxidation of methane over ceria. A theoretical solar-to-fuel conversion efficiency over 45% (with no heat recuperation) was claimed, while experimental solar-to-fuel conversion efficiencies of 9.82% (Warren et al, 2017) and later 10.6% (Warren et al, 2020) were obtained in a packed-bed-type solar reactor using solar simulator as heat source. The same research group also explored the kinetics of the partial oxidation of methane over ceria as performed under atmospheric pressure between 750 and 1,100 • C using a thermogravimetric analyzer Scheffe, 2018, 2019).…”

“…However, the reported performance was dependent on the reactor concept, design, and technology. Most of previous studies were likewise focused on thermodynamics (Krenzke and Davidson, 2014;Warren et al, 2017) and experiments (Krenzke et al, 2016;Warren et al, 2020) in small-scale reactors using electrical furnaces or solar simulators as the external heat source instead of real concentrated sunlight. Therefore, this present study aims to further examine the isothermal CLRM and H 2 O splitting over tailor-made ceria porous foams in a scalable prototype solar reactor (1.5 kW th ) using a real solar concentrating system.…”

Boosting methane partial oxidation on ceria through exsolution of robust Ru nanoparticles

“…Secondly, carbon depositions caused by methane cracking in the first step could be transformed into CO during the second step by the Boudouard reaction. 9 To guarantee the feasibility of the process, it is key to find stable redox materials that could withstand repeated high-temperature thermochemical cycling. In this respect, ceria has been widely studied due to its high structural stability at high temperatures and fast CO 2 splitting kinetics 6,10 ; being its performance tested in solar-driven reactors 9,[11][12][13] .…”

Synthesizing High‐Volume Chemicals from CO2 without Direct H2 Input

“…In the context of CCU, the use of renewable energy heating, in the form of solar thermal heating or resistive heating by renewable electricity, could further increase the CO 2 abatement potential of the processes discussed above. Indeed, the concepts of solar membrane reactor, [177,201] solar chemical looping reactor, [202][203][204][205][206] and solar fixed-bed reactor [207][208][209] have been adopted by many as the basis for achieving zero-emission dehydrogenation [210] and syngas production. [207,208] Owing to the high endothermicity, solar thermal dry reforming is also regarded as a form of solar energy storage, in which CO 2 acts as a thermochemical storage medium.…”