Low temperature catalytic oxidation of H
2
S over
V
2
O
5
/CeO
2
catalysts
V. Palma
*
, D. Barba
Department of Industrial Engineering of the University of Salerno, Via Giovanni Paolo II, 132, Fisciano, SA, Italy
article info
Article history:
Received 15 July 2014
Received in revised form
15 September 2014
Accepted 22 September 2014
Available online 17 October 2014
Keywords:
Biogas clean-up
H
2
S selective catalytic oxidation
Vanadium-based catalysts
Sulfur
abstract
CeO
2
supported vanadium catalysts at different V
2
O
5
loads (2.55e20.00 wt%) were tested for
the selective catalytic H
2
S oxidation to sulfur at low temperature.
The aim of the work is to investigate the effect of temperature and contact time in order
to realize in one step a very high H
2
S conversion, minimizing SO
2
formation.
Catalytic activity tests showed in the range 2.55e20.00 wt% the effect of the vanadium
loading plays a major role on sulfur selectivity. In particular, the 20.00 wt% V
2
O
5
/CeO
2
catalyst was the most interesting sample with a selectivity to sulfur of 99%. The H
2
S
conversion calculated experimentally at 150
C is 98.7%, very close to that obtained by
thermodynamic equilibrium calculations, corresponding to 99%.
Interesting results were also obtained from the preliminary tests on the effect of the
contact time, suggesting information relating to the reaction behavior as well as helping to
identify the optimal operating conditions capable of minimizing SO
2
selectivity.
Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights
reserved.
Introduction
Hydrogen sulfide (H
2
S) is one of the most toxic compounds
usually present in fuels, oil and gas refinery processes. In
particular, even if in little amount, it's also present in biogas,
that is a renewable energy carrier, with it being produced from
the anaerobic digestion of the organic substrates of biomass,
agricultural and industrial waste or sewage sludge. It can be
used for energy production and may be applied in direct
combustion systems (boilers, turbines) to produce space and
water heating as well as drying and steam production.
The composition of biogas varies depending on the origin
of the anaerobic digestion process. The main compounds are
CH
4
, CO
2
but they are also sulfur compounds such as H
2
S, COS
present.
For this reason, in order to increase the practical use of
biogas, H
2
S must be economically removed [1]. There are
several methods for H
2
S removal currently available,
including physical-chemical treatments that have been used
to treat tail gases containing low concentrations (<5 vol%); the
main problem of these purification processes is linked to the
high costs and limited efficiency [2].
Along with traditional catalytic oxidation processes such
as the Claus process used for the abatement of H
2
S, an inter-
esting one-step solution for the clean-up of biogas from H
2
S
could be, for small plants, selective catalytic H
2
S oxidation to
sulfur at low temperatures according to the reaction H
2
S þ 1/
2O
2
¼ 1/n S
n
þ H
2
O [3].
Unfortunately, undesired reactions may also occur such as
other oxidation reactions (Eqs. (1)e(2)) and the Claus reaction
(Eq. (3)):
* Corresponding author. Tel.: þ39 089964147; fax: þ39 089964057.
E-mail address: vpalma@unisa.it (V. Palma).
Available online at www.sciencedirect.com
ScienceDirect
journal homepage: www.elsevier.com/locate/he
international journal of hydrogen energy 39 (2014) 21524 e21530
http://dx.doi.org/10.1016/j.ijhydene.2014.09.120
0360-3199/Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.