CO₂ Capture Using Calcium Oxide Applicable to In-Situ Separation of CO₂ From H₂ Production Processes

A lab-scale CO₂ capture system is designed, fabricated, and tested for performing CO₂ capture via carbonation of very fine calcium oxide (CaO) with particle size in micrometers. This system includes a fixed-bed reactor made of stainless steel (12.7 mm in diameter and 76.2 mm long) packed with calcium oxide particles dispersed in sand particles; heated and maintained at a certain temperature (500–550°C) during each experiment. The pressure along the reactor can be kept constant using a back pressure regulator. The conditions of the tests are relevant to separation of CO₂ from combustion/gasification flue gases and in-situ CO₂ capture process. The inlet flow, 1% CO₂ and 99% N₂, goes through the reactor at the flow rate of 150 mL/min (at standard conditions). The CO₂ percentage of the outlet gas is monitored and recorded by a portable CO₂ analyzer. Using the outlet composition, the conversion of calcium oxide is figured and employed to develop the kinetics model. The results indicate that the rates of carbonation reactions considerably increase with raising the temperature from 500°C to 550°C. The conversion rates of CaO-carbonation are well fitted to a shrinking core model which combines chemical reaction controlled and diffusion controlled models.