II International Symposium on Carbon for Catalysis ABSTRACTS

PP-I-33
HYDROGEN PRODUCTION BY THERMOCATALYTIC DECOMPOSITION OF
NATURAL GAS: REGENERATION OF CARBONACEOUS CATALYSTS
Pinilla J.L., Gálvez M.E., Lázaro M.J., Suelves I., Moliner R.
Instituto de Carboquímica (CSIC). C/ Miguel Luesma Castán, 4. 50015 Zaragoza, Spain
e-mail: mlazaro@icb.csic.es
Conventional hydrogen production processes (e.g. steam methane reforming) produce large
amount of CO 2 emission. One alternative to conventional processes is single-step
thermocatalytic decomposition (TCD) of natural gas (NG) into hydrogen and carbon. Due to
the absence of oxidants (e.g., H 2 O and/or O 2 ), no carbon oxides are formed during the
process, thus obviating the need for water gas shift and CO 2 removal stages, which
significantly simplifies the process. Pure carbon is produced as a valuable by-product that can
be marketed, thus reducing hydrogen production cost.
The use of carbon-based catalyst for thermal decomposition of natural gas offers several
advantages over metallic catalysts: (i) higher fuel flexibility and no sulphur poisoning; (ii)
lower price; (iii) the carbon formed can be used as catalyst precursor, so that, the process is
self-consistent. One of the main drawbacks for the use of these materials is catalyst
deactivation mainly as a consequence of the drastic reduction in catalyst surface area during
methane decomposition due to carbon deposition. In principle, the surface area of carbon
particulates can be regenerated via their surface treatment with activating agents at elevated
temperature. High temperature steam, CO 2 or their mixtures are the most common activating
agents in the production of activating carbons from a variety of carbonaceous materials.
The objective of this work is to study the regeneration of the carbonaceous catalysts for the
TCD of methane, using CO 2 as activating agent. In previous works (1, 2), different kinds of
activated carbons (AC) and carbon blacks (CB) have been studied in the TCD of CH 4 . Among
them, a commercial AC –CG NORIT- and a CB –FLUKA 05120, have been selected for the
regeneration tests. AC showed an acceptable initial reaction rate but they become rapidly
deactivated, while CB with high surface area provided more stable and sustainable hydrogen
production.
The optimum operation conditions for the catalysts regeneration have been studied, attending
to the burn off of the catalysts during the regeneration, which is important for the self-
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