Molecular Beam Mass Spectrometry for Analysis of ... - EVUR

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Molecular Beam Mass Spectrometry for Analysis of ... - EVUR

Molecular Beam Mass Spectrometry for

Analysis of Condensable Gas Components

Tar Analysis Workshop

19 th EU Biomass Conference

Berlin

Daniel Carpenter

June 8 th 2011

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.


Background

MBMS analysis technique developed and

used by NREL for >30 years (originally to

study prompt thermochemical phenomena):

1. Line-of-sight extraction of vapor-phase sample from

high T, ambient P environment into mass

spectrometer (P source/P Stage1 ≥ 10 4 )

2. Supersonic expansion,

rapid cooling/rarefaction

preserves sample

without condensation or

reaction

3. Mass analysis provides

instantaneous chemical

fingerprint of sample

4. Useful for tar and alkali

metal vapor analysis

NATIONAL RENEWABLE ENERGY LABORATORY

0.30 mm

orifice

Stage 1 Stage 2 Stage 3

10

1.0 mm

skimmer

-5 Torr 10-7 10 Torr

-3 Torr

440 L/s 520 L/s 260 L/s

Formation of molecular beam

2


Transportable instrument for process monitoring

•Constructed field-deployable MBMS

(~1995)

Mass spectrometer cart: ~1 m 2 , 300 kg

•On-board, PC-based sample handling and

calibration control (temperature, pressure,

flow control, gas & liquid standards)

= 450°C

NATIONAL RENEWABLE ENERGY LABORATORY

1

filters liquid standard

mass

spectrometer

3

4

P

dP

2

dilution gas, calibration

gas, scrubbed gas

5 6

7

9

8

vent

1. Sample

manifold

2.Flow control

valve

3.Orifice plate

flow meter

4.Sampling

orifice

5.Condenser

6.Coalescing

filter

7.Pressure

control valve

8.Sample pump

9.Dry test meter

3


Results and experience

•Provides real-time, continuous, and robust

process monitoring of hot, untreated process gas

•Near-universal detection (typical sensitivity ~1

ppmv)

•Reproducible and stable with routine

maintenance

•Learning curve is steep, complex system

•Quantitation is somewhat cumbersome (requires

careful injection of liquid standard for each

species of interest and good measurement of wet

volumetric flow)

•Compares well with EU Tar Protocol, but

estimations of “gravimetric” tar difficult with limited

standard set (injection of heavy tar standards into

hot oven problematic due to solvent vaporization

and capillary plugging)

•Expensive (approx. $300K U.S.)

•Most valuable during plant startup and initial

product gas characterization, less valuable for

routine analysis

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Intensity (arb.)

Intensity (arb.)

1.5e+8

1.0e+8

5.0e+7

2.5e+8

2.0e+8

1.5e+8

1.0e+8

5.0e+7

16 (methane)

40 (argon)

78 94 108

3.0e+7

2.0e+7

1.0e+7

108

110

122

132

144 158

100 150 200 250 300

0 50 100 150 200 250 300 350 400

16 (methane)

40 (argon)

78

8.0e+7

6.0e+7

4.0e+7

2.0e+7

104

116

128

m/z

m/z

160

650 C

0.0

100 150 200 250 300

128

178

142

0 50 100 150 200 250 300 350 400

152

166

178

202

216

228

875 C

Mass spectra observed with MBMS during

wood gasification at 650° C and 875°C

252

4

276

290


Current status and future work

•System works, but can be made smaller, lighter, more energy efficient

with recent equipment advancements (vacuum pumps, electronics)

•Phase-sensitive detection (molecular beam chopper) could be added to

increase sensitivity by >100x

•Commercial MBMS systems are now available (Extrel CMS, Hiden

Analytical) that could easily be outfitted for the field

References:

•Evans, R.J., Milne, T.A., “Molecular Characterization of the Pyrolysis of Biomass. 1. Fundamentals” Energy & Fuels 1987, 1 (2), 123-137.

•Carpenter, D.L., Deutch, S.P., French, R.J. “Quantitative Measurement of Biomass Gasifier Tars Using a Molecular-Beam Mass

Spectrometer: Comparison with Traditional Impinger Sampling” Energy & Fuels 2007, 21, 3036-3043.

•Dayton, D.C., French, R.J., Milne, T.A., “Direct Observation of Alkali Vapor Release during Biomass Combustion and Gasification. 1.

Application of Molecular Beam/Mass Spectrometry to Switchgrass Combustion” Energy &Fuels 1995, 9 (5), 855-865.

•Carpenter, D.L., Bain, R.L., Davis, R.E., Dutta, A., Feik, C.J., Gaston, K.R., Jablonski, W., Phillips, S.D., Nimlos, M.R., “Pilot-Scale

Gasification of Corn Stover, Switchgrass, Wheat Straw, and Wood: 1. Parametric Study and Comparison with Literature” Ind. Eng. Chem.

Res. 2010, 49 (4), 1859-1871.

NREL/National Bioenergy Center: http://www.nrel.gov/biomass

DOE Biomass Program: http://www.eere.energy.gov/biomass

NATIONAL RENEWABLE ENERGY LABORATORY

5


Supplemental Slides

Additional syngas analysis methods

under development at NREL

•High-resolution mass spectrometry

•Diode laser spectroscopy

•Laser ablation, REMPI/TOF

•Advanced gas chromatography

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6


High-resolution mass spectrometry

JMS-GCmate II (JEOL Ltd., Japan) high-resolution

magnetic sector mass spectrometer installed in

TCPDU

•Motivation: analysis of very low levels of DOEtargeted

syngas impurities, e.g. NH 3, HCl, H 2S

•Modified inlet system for continuous

monitoring of syngas (still working on heated

capillary inlet for tars)

•Can resolve at m/z… 16: NH 2 + /CH4 + /O +

17: OH + /NH 3 + / 13 CH4 +

27: 13 C 2H 2 + /HCN + /C2H 3 +

28: CO + /N 2 + /C2H 4 +

NATIONAL RENEWABLE ENERGY LABORATORY

•Resolution of 5000

(m/ m) enables “accurate

mass” measurements

(elemental compositions)

Mass range: 1-3000 amu

•Sensitivity: 30 pg/ L (ppt)

•Capable of CI and direct

insertion probe operation

Relative Intensity (%)

80

44-CO2 60

100 16.0239-CH +

4

15.8 16.0 16.2 16.4 16.6 16.8 17.0

m/z

40

20

15.9877-O +

16.9957-OH +

Limitations:

•Capillary inlet may limit

throughput of high-mass

compounds

•Magnet stability vs.

ambient temperature

•Ion source robustness?

16.9957-NH 3 + 27.9912-CO + 28.0024-N 2 +

27.96 27.98 28.00

m/z

28.02 28.04

0

0 20 40 60 80 100

m/z

28.0276-C 2H 4 +

Mass spectrum of scrubbed, wood-derived syngas observed

with high-resolution mass spectrometer

7


Diode laser spectroscopy

Ramp

generator

oscilloscope

DFB-DL

BD

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Herriott cell

Photograph showing Herriott cell (top) and schematic of diode

laser spectrometer. BD – balanced detector, DFB-DL – distributed

feedback diode laser

•Based on near-IR absorption spectroscopy

• Detection limit: 0.1 ppmv

•Response time ~ 2 sec

•Expandable to multispecies detection at

roughly $5000/component

Limitations:

•Susceptible to absorption interferences,

especially water vapor

•High resolution spectroscopy unknown for

most species

Multipass pattern

observed on 2” mirror

using 660 nm alignment

laser. Effective pathlength

~ 49 meters.

Contact: David Robichaud (david.robichaud@nrel.gov)

8


Laser ablation, REMPI/TOF

• Laboratory unit for fundamental

studies

• Highly selective towards lignin

pyrolysis products (see below)

•Screening of catalysts for biomass

pyrolysis

•Study effects of mineral salts on

pyrolysis of lignin

•Classification of lignin form different

biomass feedstocks

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Sample inlet

Linear

translator Biomass

vapor

Biomass sample (wood

section/leaf/disk)

Rev. Sci. Instrum. 82, 033104 (2011)

355 nm Laser Ablation Beam

REMPI: λ = 278 nm

(4.46 eV)

He Carrier Gas

Under Free Jet

Expansion

Contact: Calvin Mukarakate (calvin.mukarakate@nrel.gov)

9


Advanced gas chromatography

•Customized Agilent 6890N & 7890A

gas chromatographs

•Accepts heated sample to 325°C

•Dual FID detectors (hydrocarbons

through C 20)

•Dual TCD detectors (permanent gases,

tracer gases)

•Nitrogen chemiluminescence detector

– NCD (9 N compounds, including NH 3,

HCN, pyrrole, pyridine at 0.05 ppmv)

•Sulfur chemiluminescence detector –

SCD (16 S compounds, including H 2S,

mercaptans, thiophene at 0.1 ppmv)

Limitations:

•Some compounds not detectable at

325°C

Analysis time – fast analysis: 8 min.,

detailed analysis: 40 min.

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sample oven

auxiliary isothermal ovens

Isothermal injector ovens

heater/valve control

NCD & SCD

Wasson-ECE Instrumentation (Ft. Collins, CO) customized GC

system for analysis of hot syngas up to 325°C.

10

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