In-situ ATR-IR monitoring of hydrothermal carbonation of wollastonite

In-situ reaction monitoring allows for the development of reaction models for hydrothermal carbonation reactions, which have recently gained attention due to their importance in CO2 sequestration and utilization. Here, we measured the carbonation kinetics of wollastonite (beta- CaSiO3) powder compacts under hydrothermal conditions (90 degrees C and 2.4 atm) with the help of optical fiber-based attenuated total reflectance infrared spectroscopy (ATR-IR). The fiber probe was positioned at the target area to study the reaction chemistry at the desired region of the powder compact. Absorbances of solid reactants and products were monitored throughout the entire reaction in the 1000-1600 cm(-1) spectral range. ATR-IR enabled the detection of amorphous silica, which allowed all solid reactants (beta-CaSiO3) and products (CaCO3 and SiO2) to be monitored independently and simultaneously. A linear proportionality constant between absorbance and CaCO3 phase concentration was determined and used to construct a reaction kinetics profile for carbonate formation, which revealed a rapid reaction onset, followed by two distinct slower decaying regimes.

Automated summary

In-situ reaction monitoring using ATR-IR was employed to investigate the carbonation kinetics of wollastonite powder compacts under hydrothermal conditions. The study revealed a rapid reaction onset followed by two distinct slower decaying regimes for carbonate formation.