Preparation of mw-assisted n-modified palm shell activated carbon for h2s removal from simulated pome biogas
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Date
2016-01-01
Authors
Norhusna Mohamad Nor
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Abstract
The presence of H2S in biogas could disturb the conversion of methane
(CH4) to renewable energy due to its corrosive effect to equipment and its toxicity to
human health. The main objective of this study is to develop a nitrogen-modified
palm shell activated carbon (N-PSAC) via microwave (MW) heating method for H2S
removal from simulated POME biogas. A preliminary study on choosing preferable
method of producing high performance of sorbent was done and MW heating method
was selected compared to conventional heating method. The preparation of a high
quality of N-PSAC sorbent was done under MW heating variables; 900 °C of MW
heating temperature, 400 ml/min of N2 flow rate, 10 minute of MW heating time and
3 g of sample amount. MW heating method provides better incorporation of nitrogen
functional groups in the N-PSAC carbon’s matrix and well-developed surface and
porous structures are believed to be predominant factors that contribute in high H2S
sorption capacity. The details characterizations of the N-PSAC sorbent before and
after H2S sorption concluded that both physical and chemical sorptions were taken
place during the sorption process. A complete breakthrough analysis of various
operating conditions namely relative humidity, operating temperature, amount of
sorbent, biogas feed flow rate and H2S feed concentration were influencing the
sorption capacity of H2S onto N-PSAC sorbent. It can be concluded that the existing
settings in Felda Besout palm oil mill (i.e. 35 °C, 45% RH and 3000 ppm H2S) are
favorable for H2S sorption by using the N-PSAC sorbent without altering the
operating parameters. The MW dry-regeneration method is proven to regenerate H2S
saturated N-PSAC sorbent up to 100% regeneration efficiency and was tested for 20
regeneration cycles. The predictions of H2S sorption equilibrium showed that
Freundlich isotherm model fitted well with the experimental data. The
thermodynamic properties evaluates the H2S sorption using N-PSAC sorbent as an
exothermic process with spontaneous and randomly distributed. The activation
energy and frequency factor for H2S sorption were found to be 15.60 kJ/mole and
3.90 x 102 cm3/g.min, respectively. The deactivation kinetic model was found to give
a very good agreement with the experimental data of H2S sorption.