Chemical Engineering Science 64 (2009) 4826--4834 Contents lists available at ScienceDirect Chemical Engineering Science journal homepage: www.elsevier.com/locate/ces Energy efficiency of hydrogen sulfide decomposition in a pulsed corona discharge reactor Sanil John a , Jerry C. Hamann b , Suresh S. Muknahallipatna b , Stanislaw Legowski b , John F. Ackerman a , Morris D. Argyle a, ∗ a Department of Chemical and Petroleum Engineering, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA b Department of Electrical and Computer Engineering, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA ARTICLE INFO ABSTRACT Article history: Received 17 February 2009 Received in revised form 8 July 2009 Accepted 24 July 2009 Available online 14 August 2009 Keywords: Hydrogen sulfide dissociation Pulsed corona discharge plasma Energy Fuel Reaction engineering Kinetics A novel pulsed corona wire-in-tube reactor with quartz view-ports allowed visual observation of the effect of charge voltage and gas composition on the corona distribution. The H 2 S conversion and energy efficiency of H 2 S decomposition in this pulsed corona discharge reactor varied at constant power (100 W) due to the selected values of the electrical parameters of pulse forming capacitance (720–2880 pF), charge voltage (11–21 kV), and pulse frequency (157–961 Hz). Low pulse forming capacitance, low charge voltage, and high pulse frequency operation produces the highest energy efficiency for H 2 S conversion at constant power. H 2 S conversion is more efficient in Ar–N 2 gas mixtures than in Ar or N 2 . These results can be explained by corona discharge observations, the electron attachment reactions of H 2 S at the streamer energies, and a proposed reaction mechanism of H 2 S dissociation in the Ar–N 2 gas mixture. The energy consumption per molecule of converted H 2 S in an equimolar mixture of Ar and N 2 (4.9 eV/H 2 S) is the lowest that has been reported for any plasma reactor operated at non-vacuum pressures. The results reveal the potential for energy efficient H 2 S decomposition in pulsed corona discharge reactors. © 2009 Elsevier Ltd. All rights reserved. 1. Introduction The annual demand for hydrogen in the US chemical and re- fining industries for 2007 was about 8.9 million metric tonn- es (www.epa.gov/climatechange/emissions/downloads/tsd/TSD%20 HydrogenProduction%20EPA_2-02-09.pdf, 2008), mainly for use as a reactant in the synthesis of ammonia and methanol and in petroleum hydrodesulfurization, hydrocracking, and upgrad- ing processes. Merchant hydrogen production for use in refiner- ies and chemical plants was about 2.0 million metric tonnes per year (www.epa.gov/climatechange/emissions/downloads/tsd/TSD% 20HydrogenProduction%20EPA_2-02-09.pdf, 2008). Although the to- tal hydrogen consumption is growing at about 4% annually, growth in the merchant hydrogen business is higher, estimated to be about 10%, as refineries shift away from captive hydrogen product- ion (http://www.the-innovation-group.com/ChemProfiles/Hydrogen. htm, 2008). With the cost of sweet crude oil increasing, refineries are processing more heavy sour crude, which requires additional hydrogen for sulfur removal. Legislation limiting sulfur content in gasoline and diesel require more hydrotreating process ∗ Corresponding author. Tel.: +1 307 766 2973; fax: +1 307 766 6777. E-mail address: mdargyle@uwyo.edu (M.D. Argyle). 0009-2509/$ - see front matter © 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.ces.2009.07.034 steps in refineries. In addition, as hydrogen is being developed as an energy carrier, the predominant hydrogen production method, steam reforming of natural gas, may be insufficient for future needs. For example, by 2040, the use of hydrogen in fuel cell powered cars and light trucks is anticipated to require annual production of approximately 136 million metric tonnes of hydrogen (Dresselhaus et al., 2004). Hydrogen sulfide (H 2 S) is a common contaminant (from ppm con- centrations to 90% by volume) in many of the world's natural gas wells. In natural gas processing, it is viewed as a pollutant because it corrodes pipelines and deactivates metal-based catalysts used in steam methane reformation (Huang and T-Raissi, 2008). Tradition- ally, H 2 S is converted via the Claus process to sulfur and water, re- sulting in a loss of the hydrogen content of the H 2 S as low-grade steam. H 2 S would be more economically valuable if both hydrogen and sulfur could be recovered. We estimate the US H 2 S production rate from natural gas plants and oil refineries to be on order of 10 million metric tonnes per year. The theoretical energy required to produce hydrogen from H 2 S is only 20.63 kJ/mol H 2 as compared to 63.17 kJ/mol H 2 for steam methane reforming and 285.83 kJ/mol H 2 for water electrolysis, all calculated from standard heats of forma- tion at 298 K (Smith and Van Ness, 1987). Therefore, H 2 S represents a significant potential future source of low-cost hydrogen, if efficient processes are developed to extract and recover the H 2 .