Overview:
Molecular beam mass spectrometer (MBMS) systems developed at the National Laboratory of the Rockies (NLR) provide analysis of harsh environments that are problematic
for other techniques. These systems can be coupled to various reactors for pulsed
(1-2 minutes per sample) or continuous product monitoring, and have been used for
laboratory studies of a variety of ambient-pressure, high-temperature, reactive systems,
including catalytic pyrolysis vapor upgrading, cracking and steam reforming of gasifier
tars, analytical pyrolysis of biomass feedstocks and products for rapid screening
of composition, and measurements of alkali metal release during biomass combustion,
co-firing, and gasification. In the MBMS system, sampled gases/vapors are first extracted
through a 300-μm critical-flow orifice and the resulting free-jet expansion causes
an abrupt transition to collision-less flow that quenches chemical reactions and inhibits
condensation. The analyte is thus preserved in its original state, allowing light
gases to be sampled simultaneously with heavier condensable and reactive species.
The resulting molecular beam is intercepted by low-energy electrons (<25 eV), and
mass spectra are generated approximately once per second so that the time-resolved
behavior of the system under study can be observed. Because the sample is introduced
continuously by this technique, with proper calibration quantitative measurement of
constituents can potentially be done once per second.
Additional Information:
NREL Molecular Beam Mass Spectrometry Fact Sheet
National Laboratory:
NLR
