Hydrogen Generation by Ammonia Decomposition over Co/CeO2 Catalyst:
Influence of Support Morphologies
Abstract
Three morphology CeO2 supports with three-dimensionally ordered
mesoporous structure (3DOM), nanotubes (NT) and nanocubes (NC) were
synthesized by nanocasting of a mesoporous silica KIT-6 template with
cubic Ia3d symmetries, hydrothermal method with and without urea,
respectively, and supported cobalt catalysts were investigated on the
production of COx-free hydrogen from ammonia decomposition for
300-600ºC. Morphological structure of CeO2 significantly influenced the
catalytic activities in the ammonia decomposition, and the Co/CeO2-3DOM
catalyst had a higher catalytic performance than Co/CeO2-NC and
Co/CeO2-NT. It was elucidated by the formation of smaller particles size
and more oxygen vacancies. The Co/CeO2-3DOM catalyst exhibited good
stability and reusability at 600ºC for ammonia decomposition due to the
three-dimensionally ordered mesoporous structure as anchoring cobalt
active sites and prevention from active site aggregation. A mechanistic
insight has been presented to understand the structure-activity
relationship based on the structure of the CeO2 supports.