Looping Cycles for Low Carbon Technologies

In the last decades a potpourri of looping processes for clean utilization of fossil sources has been proposed and studied as a transient solution towards zero-emission energy. The present paper examines looping processes recently proposed and developed for both carbon oxidation/gasification and CO2 capture and transformation. Selected scientific issues associated to dynamic operation are also investigated by means of an innovative experimental technique based on a twin-bed reactor. Combustion and gasification: Chemical looping with oxygen uncoupling (CLOU) and CarboLoop processes accomplish combustion or gasification of coal and more generally of solid fuels through reiterated alternation of oxidation and desorption steps. The literature on carbon combustion generally refers to continuous operating conditions, whereas dynamical effects have not been deeply investigated. The aim of the present study is to contribute to a better understanding of the mechanism and chemistry of carbon oxidation throughout dynamic oxidizing/reducing cycles. CO2 capture: Calcium Looping (CaL) provides a feasible and robust path to accomplish carbon capture from CO2-bearing exhaust [2]. Efficiency of CaL is affected by sorbent thermal sintering (deactivation) upon iterated looping and by particle attrition/fragmentation. A less scrutinized issue is the concurrent effect of steam and SO2 in terms of sorbent availability and selective uptake. This study aims at a deeper investigation of the performance of Ca-based sorbents in ternary CO2-SO2-H2O systems. CO2 transformation: In Sorption-Enhanced Methanation the steam generated by methanation is removed from the gas phase in a catalytic bed by adding a sorbent material. CO2 methanation in combination with chemical storage, solar fuels and CO2 utilization [3] is particularly interesting. In this work an innovative configuration, based on two interconnected fluidized beds, is investigated.