(186b) Cleanup of Coal Gases by Removing Hydrogen Sulfide in the Form of Liquid Element Sulfur
AIChE Annual Meeting
2006
2006 Annual Meeting
Catalysis and Reaction Engineering Division
Fundamentals of Environmental Catalysis I
Tuesday, November 14, 2006 - 8:50am to 9:10am
Removal of hydrogen sulfide (H2S) from coal gases and sulfur
recovery as elemental sulfur are key steps in the development of advanced power
plants that employ coal and natural gas, and produce electric power and clean
transportation fuels. The conventional method of sulfur removal and
recovery employing amine scrubbing, Claus, and tail-gas treatment involves a
number of steps and is energy intensive. A novel process called
Single-Step Sulfur Recovery Process (SSRP) is under development at various
research groups. In this process, the H2S in the coal gas is
selectively oxidized in a single step to elemental sulfur using sulfur dioxide
(SO2) or oxygen (O2) in the presence of
alumina-or-carbon-based catalyst pellets in a packed/fluidized bed.
A monolithic catalyst reactor (MCR) for the development of a single-step
sulfur recovery process is used to remove H2S from a simulated coal
gas in this study. Sulfur dioxide is used as an oxidizer to convert H2S
into liquid element sulfur at 125 to 155oC. The monolith
catalyst is wash-coated with gamma alumina oxide. A performance of the
monolithic catalyst is presented in terms of H2S removal capacity,
deactivation, and selectivity of COS with various catalyst promoters at various
reactor operation conditions.
The objectives
of this research are to formulate monolithic catalysts for removal of H2S from coal gases and
minimum formation of COS with monolithic catalyst supports, gamma-alumina wash,
and catalytic metals, to develop a catalytic regeneration method for a
deactivated monolithic catalyst, to
measure kinetics of both direct oxidation of H2S to elemental sulfur with SO2 as an oxidizer and selective formation of COSin the presence of a simulated coal gas mixture containing H2, CO, CO2, and moisture, using a monolithic
catalyst reactor. This heterogeneous catalytic reaction has gaseous reactants
such as H2S and SO2. However, this heterogeneous catalytic reaction has
heterogeneous products such as liquid elemental sulfur and steam. The molar
ratio of H2S to SO2 in the monolithic
catalyst reactor is maintained at 2 for all the reaction experiment runs.
Experiments on
conversion of hydrogen sulfide into elemental sulfur and selective formation of
COS are carried out for the space time range
of 90 ? 560 seconds at 125 - 155oC and 40 ? 200 psia to evaluate effects
of reaction temperature, moisture concentration, space time, pressure, and
catalyst age on conversion of hydrogen sulfide into elemental sulfur and selective
formation of COS.