Low-Temperature H₂S Removal from Steam-Containing Gas Mixtures with ZnO for Fuel Cell Application. 2. Wash-Coated Monolith

Abstract

This work is part of our efforts to explore more-effective ways to remove hydrogen sulfide (H 2 S) for fuel cell applications. Various absorbents (ZnO, SnO 2 , coprecipitated NiO-MoO 3 , supported CuO-ZnO, V 2 O 5 -ZnO, and ZnO supported on γ-alumina) were tested for H 2 S removal. The absorbents that were wash-coated onto the monolith were compared with particulate traps in the inlet H 2 S concentration range of 0.5-8 parts per million by volume (ppmv). The monolith provides much-higher dynamic capacity (the amount of H 2 S trapped before breakthrough) under the same conditions. The ZnO-based monolith demonstrated the best performance. An extremely low H 2 S outlet concentration (as low as 20 parts per billion, by volume (20 ppbv)) was observed over ZnO-based monolith samples for extended periods of time, under various conditions relevant for the desulfurization of gas products from the autothermal reforming of hydrocarbon fuels for a proton-exchange membrane fuel cell. The capacity of the H 2 S trap is dependent on the monolith characteristics (active component loading per cubic inch, and the number of cells per square inch) and operating conditions (including inlet H 2 S concentration, space velocity, and temperature). Wash-coating of ZnO that was chemically modified by an ammonium carbonate treatment onto a monolith with 400 cells per square inch gave the best H 2 S absorbence with higher dynamic capacity.

Effects of coal syngas impurities on anodes of solid oxide fuel cells

“…Sulfur-containing compounds, which are primarily, present as H 2 S in the coal syngas have received most attention [10][11][12][18][19][20] since they are known to have a significant impact on SOFC anode performance [10]. Several possible mechanisms may account for the performance degradation of the Ni-YSZ anode due to presence of H 2 S in the fuel.…”

Design of a Sorbent to Enhance Reactive Adsorption of Hydrogen Sulfide

“…6,7 Furthermore, hydrogen sulfide can convert to SO 2 during combustion, which is also corrosive and causes acid rain. 8 With increasingly environmental regulations, the emission of sulfur compounds is limited greatly. 9 Therefore, searching for various materials with excellent desulfurization performance is urgent and very meaningful.…”

H2S removal with ZnO during fuel processing for PEM fuel cell applications

“…In this work, we have measured the performance of a commercial H 2 S absorbent, ZnO, as a desulfurizer for this system. Although ZnO has been well-studied with hydrodesulfurized feedstocks [3][4][5], the performance of ZnO in removing sulfur from steam reformate in small on-board units at high space velocities does not appear to have been studied in detail.…”