High-temperature and high-pressure cell for kinetic measurements of supercritical fluids reactions with the use of ultraviolet-visible spectroscopy

A high-temperature high-pressure ultraviolet-visible (UV-Vis) cell is described. The cell has been designed specifically for use with the UV spectrophotometer Hewlett–Packard 8453 but it could work up to 780 K at 100 MPa with any other UV-Vis spectrophotometer, as well as for near infrared (NIR) experiments. Three features of the cell make it convenient for experiments with supercritical fluids: the possibility to choose an optimal path length, the presence of three interchangeable ports into the cell, and a movable thermocouple in the working zone of the cell. The cell has been used to study a range of chemical reactions in water under near-critical and supercritical conditions, as well as for measuring the kinetics of such reactions. Some examples illustrating the performance of the cell are given.