Chemical looping processes for CO2 capture and carbonaceous fuel conversion – prospect and opportunity

Abstract

Chemical looping processes offer a compelling way for effective and viable carbonaceous fuel conversion into clean energy carriers. The uniqueness of chemical looping processes includes their capability of low cost in situ carbon capture, high efficiency energy conversion scheme, and advanced compatibility with state-of-the-art technologies. Based on the different functions of looping particles, two types of chemical looping technologies and associated processes have been developed. Type I chemical looping systems utilize oxygen carrier particles to perform the reduction-oxidation cycles, while Type II chemical looping systems utilize CO 2 carrier particles to conduct carbonation-calcination cycles. The exergy analysis indicates that the chemical looping strategy has the potential to improve fossil fuel conversion schemes. Chemical looping particle performance and looping reactor engineering are the key drivers to the success of chemical looping process development. In this work, the desired particle characterization and recent progress in mechanism studies are generalized, which is followed by a discussion on the looping reactor design. This perspective also illustrates various chemical looping processes for combustion and gasification applications. It shows that both Type I and Type II looping processes have great potentials for flexible and efficient production of electricity, hydrogen and liquid fuels.

Syngas/H2 production from bioethanol in a continuous chemical-looping reforming prototype

“…A dry syngas composed by ≈59-62 vol.% H 2 , ≈36-27 vol.% CO, ≈1-10 vol.% CO 2 , and ≈1-3 vol.% CH 4 was experimentally obtained in the CLR unit using ethanol as fuel for both oxygen carriers at these operating conditions. The syngas composition was quite similar in comparison to that obtained using CH 4 as fuel [9]. If we consider that the syngas produced is further associated with a WGS and a H 2 /CO 2 separation unit, a final amount of ≈4.8 moles of H 2 could be finally obtained per mol of ethanol fed.…”

“…Table 1 The gases were fed by means of specific mass-flow controllers. The ethanol and water were injected to a heater (10) using two peristaltic pumps (9). The liquids were evaporated and then fed into the FR mixed with N 2 .…”

“…Among them, chemical looping is considered as the highest technology regarding cost reduction benefit among all available options although the time to commercialization is expected to be large [8,9].…”

Chemical looping combustion process in fixed-bed reactors using ilmenite as oxygen carrier: Conceptual design and operation strategy

“…Furthermore, rapid mixing of the solids ensures an adequate control of the temperature, which is of fundamental importance in the energy-intense reactions characteristic of CLC processes. The application of the CLC concept in fluidized-beds has been widely studied in recent years in several experimental units at different pilot scales [13][14][15][16][17][18][19][20]. However, the use of interconnected fluidized-beds in CLC has several drawbacks.…”

“…CLC was firstly conceived in the 1950s [5], but it was not until the 1990s when it was proposed as a CO 2 capture system [6]. Most of the CLC configurations proposed consist of interconnected fluidized-bed reactors, where the oxygen carrier is reduced in the fuel reactor and rapidly transported to the air reactor to be regenerated [7][8][9][10][11][12][13][14]. The small size of the particles used in fluidized beds ensures that there is good contact between the gas and solids, as a result of which the kinetics of the reactions involved in the process are considerably enhanced.…”