Analytical Sciences

Simultaneous Online Measurement of H₂O and CO₂ in the Humid CO₂ Adsorption/Desorption Process

Qingni YU,*,** Sha YE,* Jingke ZHU,* Lecheng LEI,* and Bin YANG*

*Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, P. R. China
**China Astronaut Research and Training Center, Beijing 100094, P. R. China

A dew point meter (DP) and an infrared (IR) CO₂ analyzer were assembled in a humid CO₂ adsorption/desorption system in series for simultaneous online measurements of H₂O and CO₂, respectively. The humidifier, by using surface-flushing on a saturated brine solution was self-made for the generation of humid air flow. It was found that by this method it became relatively easy to obtain a low H₂O content in air flow and that its fluctuation could be reduced compared to the bubbling method. Water calibration for the DP-IR detector is necessary to be conducted for minimizing the measurement error of H₂O. It demonstrated that the relative error (RA) for simultaneous online measurements H₂O and CO₂ in the desorption process is lower than 0.1%. The high RA in the adsorption of H₂O is attributed to H₂O adsorption on the transfer pipe and amplification of the measurement error. The high accuracy of simultaneous online measurements of H₂O and CO₂ is promising for investigating their co-adsorption/desorption behaviors, especially for direct CO₂ capture from ambient air.

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