Author: Jie YuPublisher:
ISBN:
Category : Carbon dioxide mitigation
Languages : en
Pages : 213
Book Description
CO2 capture and sequestration from coal-fired power plant flue gas is an attractive technique to control CO2 emissions. Polyamine-based sorbent is considered as a promising sorbent for CO2 capture due to its low equipment corrosion and regeneration energy penalty. One critical aspect of development of polyamine-based CO2 capture process is to understand the nature of the adsorbed species with amine and their evolution in adsorption / desorption process. Fourier transform infrared (FTIR) spectroscopy is a powerful and versatile tool that can provide the insights from molecular level to address these scientific issues. This dissertation is focusing on using in-situ FTIR spectroscopy to discuss several important topics in CO2 capture and utilization processes, including (i) the structure and binding energy of adsorbed CO2/H2O on solid amine sorbent, (ii) the role of H2O in CO2 adsorption/desorption on liquid amine films, (iii) mechanism of water-enhancement on CO2 capture by amine, and (iv) photoelectrocatalytic reduction of CO2 on polyamine/TiO2 thin film.H2O vapor in flue gas has dramatic effects on polyamine-based sorbent. H2O could affect CO2 capture capacity, regeneration energy, and degradation kinetics of the sorbents. This in situ IR study investigated these various effects on polyamine-based sorbents. The results revealed that CO2 adsorbed on primary amine as ammonium carbamate while H2O adsorbed on secondary amine and promoted the formation of carbamic acid. Adsorbed H2O increases the binding strength of CO2 with amine and protects sorbent from SO2 poisoning. The results of this study clarify the role of H2O in polyamine-based sorbent for CO2 capture and provide a molecular basis for the design and operation of polyamine-based CO2 capture processes. The use of FTIR spectroscopy in the investigation of role of water on CO2 capture by amine has enabled us to verify the reaction processes. The results unraveled that adsorption of CO2 on the 20 μm tetraethylenepentamine (TEPA) film at 50 °C followed a zwitterion-intermediate pathway: zwitterion ¿ ammonium carbamate. H2O in the mixed TEPA/H2O (5:1) film decreased the rate of CO2 adsorption, but increased the amine efficiency. The presence of H2O promotes the formation of carbamic acid and produces a broad IR band centered at 2535 cm-1, which can be assigned to (O-H) of hydronium carbamate, -NCOO-···H-OH2+. The broadness of this 2535 cm-1 band ranging from 2100 cm-1 to 2800 cm-1 persists at 120 °C. These broad components of the band can be ascribed to ¿(N-H) in hydrogen-bonded ammonium carbamate, a R-NH3+/R1R2-NH2+···-NCOO- moiety. The binding strength of adsorbed species on the TEPA film increases in the order: adsorbed H2O
