(478b) Decomposition of H2S and CH4 in Pulsed Corona Discharge Reactors | AIChE

(478b) Decomposition of H2S and CH4 in Pulsed Corona Discharge Reactors


John, S. - Presenter, University of Wyoming
Zhao, G. - Presenter, University of Wyoming
Zhang, J. - Presenter, University of Wyoming
Wang, L. - Presenter, University of Wyoming
Muknahallipatna, S. S. - Presenter, University of Wyoming
Hamann, J. C. - Presenter, University of Wyoming
Ackerman, J. F. - Presenter, University of Wyoming
Plumb, O. A. - Presenter, University of Wyoming

Decomposition of H2S and CH4 in
Pulsed Corona Discharge Reactors


Natural gas typically contains
70-90% methane (CH4) and 0-5% hydrogen sulfide (H2S). The
conversion of CH4 to hydrogen and more valuable hydrocarbons, like ethylene,
is of great importance to the petrochemical industry.  Direct decomposition of
H2S to yield hydrogen and sulfur is desirable compared to the
conventional Claus process, which converts H2S into sulfur and water.
 CH4 and H2S have been separately decomposed in our
experiments in a wire-in-tube pulsed corona discharge reactor.  The pulsed
corona discharge is a good source for generating chemically active species at
room temperature, which initiate chemical reactions leading to CH4 and
H2S conversion.


A corona discharge was achieved
with our present reactor configuration after pure H2S was diluted
with argon.  The effects of charge voltage, capacitance and frequency on
reaction rate and energy efficiency were studied for different concentrations
of H2S in argon.  At constant power input (100 W), low capacitance
(720 pF) operation gave the highest conversion and lowest energy consumption
for H2S decomposition.  The effect of mixed argon-nitrogen diluents
on H2S conversion is being studied.


The effect of capacitance,
cathode material, gas flow rate and specific energy input on conversion, energy
efficiency, and product selectivity on CH4 decomposition was also
studied.  Ethane and acetylene appear to be formed from dimerization of CH3
radicals and CH radicals, respectively, while ethylene is formed mainly from
the dehydrogenation of ethane.  At a given power input, low capacitance (1280
pF) with high pulse frequency (1000 Hz) results in higher CH4
conversion and energy efficiency than operation at high capacitance (1920 pF)
with low pulse frequency (200 Hz).  Platinum coated stainless steel cathodes
slightly enhance CH4 conversion relative to stainless steel
cathodes, perhaps due to a weak catalytic effect.  As specific energy input
increases, energy efficiency for CH4 conversion goes through a
minimum, while the selectivity of acetylene has a maximum value.