Heat of absorption and specific heat of carbon dioxide in aqueous solutions of monoethanolamine,3-piperidinemethanol and their blends

Abstract

In this work the thermodynamic properties of monoethanlonamine (MEA), 3-piperidinemethanol (3PM) and their blends were measured and evaluated. The heat of absorption of the solution of CO2 in the aqueous solution of single amines (5 M MEA,3 M MEA, 2 M MEA, 2 M 3PM and 3 M 3PM) and aqueous amine blends (2 M MEA+ 3 M 3PM, 3 M MEA + 2 M 3PM, 3 M MEA + 3 M 3PM) were measured isothermally using a commercially available micro-reaction calorimeter (μRC) at three different temperatures (313.15, 333.15 and 353.15) K and at different CO2 loading capacity. The vapour liquid equilibrium apparatus was also used to obtain different samples of loaded CO2 molCO2/molamine and their corresponding heat of absorption was measured using the micro-reaction calorimeter. In addition, the heat capacities of the above amines were also measured from 303.15 K to 353.15 K at an interval of 5 K. The calorimetric measurements of the heat of absorption at temperature (313.15 oK) indicated that the (3 M MEA + 2 M 3PM) blend has the lowest absorption enthalpy with 75.58 kJ/mol CO2 at 0.56 molCO2/molamine (max loading capacity) than (5M-MEA) with a reported value of 87.827 kJ/molCO2 at 0.51 molCO2/molamine which corresponds the maximum loading capacity of (5M-MEA). The (3 M MEA + 3 M 3PM) exhibited the lowest heat capacities among the measured blends of MEA and 3PM. 5 M MEA was used as a base case for all the experimental measurements for the heat of absorption.