This work was focused on the possibility of applying the same
concept in catalyst design to be implemented in two thermal
processes involved in sewage treatments plants for energy
valorisation for hydrogen production: biogas direct reforming
(carbon dioxide methane reforming) and tar conversion in
sewage sludge gasification. The catalyst deactivation phenomena
in both processes was coke deposition on catalyst
surface, and the strategy to overcome it proposed in this work
was the same.
Catalyst designed and synthesized achieved equilibrium
values predicted by thermodynamic equilibrium for direct
carbon dioxide methane reforming. The catalyst tested in
long-term experiments up to 95 h demonstrated total stability
in methane and carbon dioxide conversion as well as products
distribution.
On the other hand, catalyst tests in model gasification
streams showed total toluene and methane conversion
without by-products (tar) formation, levels maintained in the
long-term experiments.
Post-reaction catalyst samples characterisation by
SEM, TPO and XPS demonstrated the lack of carbon
deposits responsible of catalyst deactivation which corroborates
the stability of the reaction tests. The results obtained
allow the scale up of both processes to have and
integral solution for hydrogen production from sewage
treatment plants