Chemical processing in high-pressure aqueous environments. 1. Historical perspective and continuing developments

Abstract

Use of high-temperature pressurized liquid water has been investigated as a reaction medium for conducting chemical reactions and conversion. Results of these studies have demonstrated that high-temperature pressurized liquid water, especially in the presence of suitable catalysts, has unique chemical and physical properties. An overview of fundamental investigations and processing considerations in this environment is presented including details regarding the effects of temperature, pressure, and catalysis. The reactivities of various feedstocks tested are discussed along with the development and scale-up of high-pressure reactor systems used to investigate the process chemistry and engineering. Several new processing concepts were developed for gasification, destruction, and gas processing based on these findings. Most of the research has centered on catalytic processing for the production of liquid and gaseous fuels from biomass and wastes at lower temperatures and higher pressures than conventionally used. Other studies have investigated new methods for carrying out chemical reactions, separations, and the destruction of hazardous organic materials. All of this research has in common the use of high-pressure, water systems operating at below and above critical conditions.