In the offshore oil and gas industry an aqueous scavenger solution of triazine is often used to remove the toxic gas H2S. Though triazine has been used for decades in the industry, only limited kinetics data is available for the scavenging reaction.
In this project it was attempted to develop a methodology and experimental setup for obtain-ing kinetics data with the help of Raman spectroscopy and check feasibility of both for online monitoring of the aqueous phase reaction between 1,3,5-tri-(2-hydroxyethyl)-hexahydro-s-triazine (HET) and HS-, and a setup for obtaining kinetics data is attempted developed.
Raman spectroscopy demonstrated development of specific peaks in the spectra indicating the reaction. Relating the intensity of the peaks to a concentration of HET and HS-, it was possible to quantify the consumption of reactants over time. Experiments in the pH range of 10.3 and 8.5 was conducted and indicated that the scavenging reaction is pH dependent and is faster at lower pH. At pH 11 no reaction was observed within two hours. HS-/HET conver-sion ratios between 1 and 2 indicate that a second scavenging reaction is occurring, which was found to be the reaction between thiadiazine and HS-.
Four different setups were tested, varying how the acid was added to the system. None of the tested setups proved adequate, as they all had insurmountable disadvantages. Based on the experimental data a kinetics expression dependent on concentration of H+ and HET is proposed.