Capture of carbon dioxide from flue/fuel gas using dolomite under microwave irradiation

• We develop microwave heating system to capture CO2 by a packed bed of dolomite.
• Dolomite shows consistent CaO conversion of 90% within 15 cycles in TGA tests.
• We capture CO2 from producer gas using a packed bed of dolomite heating under microwave.
• We find that carbonation kinetics is governed by both chemical reaction and diffusion.

Naturally occurring dolomite is a low cost CO2 sorbent with superior performance to well known limestone. In this work, a microwave heating system was developed to carry out the CO2 capture experiment using a packed bed of calcined dolomite. Preliminary tests were performed in thermogravimetric analyzer (TGA) from which the calcination–carbonation temperatures of 750–700 °C were found as the suitable condition to obtain a conversion of 90% that could be sustained during 15 cycles of CO2 capture and release. Dynamic breakthrough curves of CO2 capture were developed by introducing different concentrations of CO2 (10–50 vol% in N2) into a packed bed of calcined dolomite heating under microwave irradiation. The appropriateness of the developed system was further examined through its implementation for CO2 capture from a gas stream simulating air gasification producer gas. The regenerability of the bed was assessed in three cycles of calcination–carbonation (750–700 °C) in microwave where the sorbent revealed a high and relatively sustainable performance for CO2 capture. Kinetic studies based on shrinking core model deduced that the carbonation reaction mechanism in the packed bed was governed by a combination of chemical reaction and CO2 diffusion.

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