Pulsed Breakdown and Plasma-Aided Phenol Polymerization in Supercritical Carbon Dioxide and Sub-Critical Water

This paper deals with two fundamental experimental studies with respect to plasma processes in highly pressurized carbon dioxide (CO2) and water: pulsed discharge phenomena in CO2 up to supercritical condition as a basic study of plasma production and polymerization of phenol with a pulsed discharge plasma in sub-critical water as an application of a discharge plasma for chemical reactions. The experiments showed that: 1) the measured electrical breakdown voltage in supercritical CO2 had a relatively large dispersion compared with that in the gas and liquid phases, and was almost independent of the CO2 density, 2) the delay time for breakdown increased gradually with increasing density, and there was a large fluctuation around the sub-critical phase or high-pressure gas phase, 3) the highest conversion of phenol into products in the water experiments under temperatures of 301 to 525 K and pressures of 0.1 to 20 MPa was about 17% under the experimental condition of 52 3 K, 20 MPa and 4 000 pulsed discharge shots and 4) phenol synthesis could only be obtained at higher temperatures in pulsed discharge plasma.