Mass spectrometer sampling of supercritical water-oxidation reactions
- Univ. of California, San Diego, La Jolla, CA (United States)
Supercritical water is a useful medium for oxidation of toxic hydrocarbons because under such conditions hydrocarbons and oxidizers are dissolved into a single phase, diffusivities are high, the combustion is complete, and it occurs at relatively low temperatures. There is a large literature on the thermodynamics, kinetics, and applications of supercritical water oxidation. Supercritical fluids have also been used as solvent carriers in chromatography and the interface of the column output to mass spectrometers has been investigated by many researchers. In the present investigation the authors seek to operate a micro-reactor in which supercritical water oxidation kinetics can be examined and for which the output flow can be injected directly into a mass spectrometer system. The motivation for this approach was the microjet burner utilized by Groeger and Fenn for combustion studies. Water is one of the more difficult supercritical solvents to interface with the mass spectrometer, compared with CO{sub 2} for example, because the pressures and temperatures are of order 30MPa and 500{degrees}C, and because the large water throughput must be removed by the vacuum pumps. They have fabricated supercritical nozzles from both stainless steel and from quartz capillary tubing. Despite the fact that supercritical water can dissolve quartz in the ppm range they have been able to operate quartz capillary reactors and nozzles in excess of 20hrs without any measurable degradation in performance. Because these nozzles are much easier to fabricate, especially to diameters below 0.004cm, they have been recently using them exclusively. This variable nozzle diameter is important because it permits us to vary the range of residence times in the reactor. The converging nozzle length is less than two capillary diameters, so the flow time through the nozzle is very short compared with the residence time in the reactor.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- OSTI ID:
- 110835
- Report Number(s):
- NREL/CP-433-7748; CONF-9410343-; ON: DE95004052; TRN: 95:005145-0010
- Resource Relation:
- Conference: Applications of free-jet, molecular beam, mass spectrometric sampling conference, Estes Park, CO (United States), 11-14 Oct 1994; Other Information: PBD: Mar 1995; Related Information: Is Part Of Applications of free-jet, molecular beam, mass spectrometric sampling: Proceedings; Milne, T. [ed.]; PB: 305 p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Novel technique for coal pyrolysis and hydrogenation product analysis
Novel technique for coal pyrolysis and hydrogenation product analysis. Final technical report