Investigation of Gas-Phase Pentane Pyrolysis
Kinetics over an Extended Pressure range
Gregory Bogin Jr
Assistant Professor
Mechanical Engineering
Colorado School of Mines
Golden, CO
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Goal is to characterize gas-phase pyrolysis
kinetics of pentane over wide T and P ranges
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HPFR objectives:
• Quantitatively characterize the
conversion and product distribution of
pentane at elevated temperatures (>
500°C) and pressures (1.8 -10.8 bar)
• Investigate molecular weight growth
(MWG) pathways that could lead to
deposits
Colorado School of Mines
Exhaust cooling
Reactor section
Pre-heater section
CSM-HPFR:
• Fast residence times (~ 30 ms)
• Elevated pressures (~ 30 atm)
• Elevated temperatures (~ 1100°C)
• High flow rates (500 LPM at 850°C)
• Liquid and gaseous fuels
• Water-cooled gas sampling probe
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Process flow schematic for the High
Pressure Flow Reactor (HPFR)
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Colorado School of Mines
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Mixer designed for homogeneous mixture formation
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Heated N2 and fuel mixer upstream of reactor
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Turbulent flow with reactor to
provide “plug-flow like” conditions
Uniform temperature profile
Uniform velocity profile
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Pentane conversion and ethylene production
more sensitive to temperature than pressure
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Colorado School of Mines
Ethylene is a major product of pentane pyrolysis and is desirable from an
endothermic process but has the potential to lead to soot
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Alkane production more sensitive to
temperature and pressure
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Colorado School of Mines
• For the 500°C conditions C1-C2 nalkanes had moderate increases in
production with no production of ≥C4
n-alkanes
• For 650°C conditions the production
of butane was observed in small
concentrations.
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Propylene and 1,3-butadiene are strongly
affected by both pressure and temperature
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Colorado School of Mines
• For temperatures ranging from 500°C
to 750°C, isobutylene and cis-2butene were all at the 0-2 ppm level
• Increasing pressure at 500°C had no
measureable affect on 1,3-butadiene,
1-butene, and isobutylene
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2-Pentene favored over other isomers
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Colorado School of Mines
• 1-pentene, trans-2-pentene, cis-2-pentene, and 2-methyl-2-butene
were all below 5 ppm at 1.8 bar with 5% fuel over the temperature
range 600°C - 750°C
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Acetylene and propadiene appear along with
benzene at 750°C
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Colorado School of Mines
• Very strong temperature dependence observed
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At higher temperatures also observe higher
alkanes
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Colorado School of Mines
1.8 bar
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Butadiene and benzene production begin at
lower temperature at higher pressure
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Benzene production occurs after an increase in 1,3-butadiene with an
increase in temperatures and pressures
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Conclusions/Next Steps
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Colorado School of Mines

Molecular weight growth products increase significantly at increased
pressure and temperature

Next steps:
– Lower fuel dilution and/or longer residence times will be selected to
allow higher conversion of pentane
– Continue validation of pentane cracking mechanisms and resulting
products leading to coke formation for a wide range of pressures (≥
30 bar) and temperatures (500- 900°C)
– Investigate the impact of adding light olefins (e.g. ethylene ) and
hydrogen to parent fuel to simulate the impact of catalytic reactions
– Contrast gas-phase results with those when reactor lined with
catalyst
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