The Enhancement of the Ammonium Bicarbonate Synthesis Using Non-Thermal Plasma

Abstract
A kinetic study of carbon dioxide activated by non-thermal plasma (NTP), injected as a fine bubbles, to produce highly energetic species is shown to enhance reaction yield. The study shows the yield of the reaction of CO2 and aqueous ammonia to produce ammonium bicarbonate is enhanced by 36% relative to the conventional staging process i.e. in absence of non-thermal plasma. The ratio of captured CO2 by the reaction estimated to be better than that reported (15-20 %) by Mani et al. (2006).
A chemical kinetics model for NTP to activate CO2 molecules is developed using the fine element method, implemented in the Comsol Multiphysics software package. The model dynamically evaluates vibrationally excited levels and associated species concentrations evolution. Furthermore, thermogravimetric analysis (TGA) study is conducted to determine kinetic parameters of thermal decomposition under non-isothermal conditions for three ammonium solid salts. The TGA data is combined with pseudo-inverse method (PIM) to infer the composition of an unknown binary mixture of ammonium salts, in order to develop a reliable estimate of the composition of ammonium salts. Results of the PIM for the bicarbonate /carbamate characterization show a good agreement between the modelling and experimental data, while other mixtures results are not sufficiently well inferred from the approach.
The influence of operating parameters of the reaction CO2 with aqueous ammonia solution are studied. Empirical models based on the process operating parameters are developed to show the significance of the parameters through the response surface methodology. At an applied voltage of 3.5 kV, CO2 flow rate of 0.8 LPM with 3.4 M. NH3 (aq.) concentration, and reaction time of 40 minutes, the maximum electrical conductivity of 167 mS and 60 % process yield are achieved.
The difference between the theoretical value of liberated heat during the reaction and the experimental value in this study is about 1.6 kJ that can represent a temperature range of 2-3 °C. This indicates negligible losses are incurred by plasma joule heating and sensible heating.