11CO2 positron emission imaging reveals the in-situ gas concentration profile as function of time and position in opaque gas-solid contacting systems.

• In situ analysis of an industrial process by positron emission tomography (PET) • The 3D-PET gives insight into the adsorption of 11CO 2 tracer gas on zeolite and activated carbon. • It is demonstrated that PET can determine the kinetics of high-pressure CO 2 adsorption. • This work fosters further studies of systems where the gas–solid interaction is of primary importance. The in situ analysis of industrial processes, mostly conducted in opaque equipment is difficult. Whereas previously the positron emission technique was successfully applied to study the flow and mixing in gas–solid and liquid–solid systems using radio-active tracer particles, research on imaging a radio- active tracer gas is scarce. The present paper demonstrates the use of a fully three-dimensional (3D) Positron Emission Tomography (PET) in imaging the adsorption of 11CO 2 tracer gas, while validating the measurement by conventional exit gas analysis. It will be demonstrated that PET can be used to measure the kinetics of high-pressure CO 2 adsorption in situ , including the essential breakthrough and mass transfer zone characteristics. Such high-pressure operation is characteristic of pre-combustion CO 2 capturing processes. It is expected that this work will foster further studies of gas–solid systems of adsorption, gas–solid catalysis, gas–solid hydrodynamics, and processes where the gas–solid interaction is of primary importance. [ABSTRACT FROM AUTHOR]