| Our goal is to measure the kinetics of TiCl4 oxidation at high temperatures using a rapid compression piston system (RCM). The reactor is a piston/cylinder containing gas mixtures (typically 1% O2 + 0.3% TiCl4 in Ar). The mixture is rapidly compressed, causing temperatures of the gas to rise, resulting in reaction. We have designed our compression method so that the piston bounces at the end of its stroke, causing a relatively narrow temperature peak. Depending on operating conditions, this temperature peak is two to five times the initial temperature, which allows us to reach maximum peak temperatures of 1800–2000 K when the initial temperature is 400 K.; In order to determine kinetic parameters accurately, it is essential to have an accurate estimate of the temperature variation during the course of compression. We find that at any instant, there is a spatial non-uniformity in the temperature distribution in our reactor. However, a simple hot-core model describes this variation satisfactorily. Therefore, by measuring the volume (V(t)) and pressure (P( t)) instantaneously during compression, we can estimate the temperature of the hot core (T(t)) inside the reactor. A simple batch reactor model uses this time varying temperature to determine the conversion in the piston reactor.; The gas is compressed at different conditions resulting in peak temperatures ranging between 800 K to 2100 K with reaction times of 20–80 ms. We analyze the gas mixture before and after compression using Fourier transform infrared (FTIR) spectroscopy to determine the fractional conversion of the TiCl4 reagent. Using first order reaction kinetics, a model for predicting the fractional conversion of TiCl4 is developed. Regressing the data to the model yields an activation energy of 108.8 kJ/mole and an Arrhenius pre-exponential, A, of 4.4 × 105 s−1. The activation energy measured in our RCM is consistent with measurements in the literature. However, the rate constant measured in our RCM is a factor of five higher than those reported by other authors. (Abstract shortened by UMI.)... |
