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

Abstract

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.