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Synthesis of a Highly Stable Pd@CeO2 Catalyst for Methane Combustion with the Synergistic Effect of Urea and Citric Acid
journal contribution
posted on 2018-12-06, 09:14 authored by Guohui Cai, Wei Luo, Yihong Xiao, Yong Zheng, Fulan Zhong, Yingying Zhan, Lilong JiangMaking use of synergy between urea
and citric acid, a core–shell
Pd@CeO2 catalyst with spherical morphology was facilely
synthesized by a hydrothermal method. The formation mechanism of the
core–shell structure in the presence of citric acid and hydrogen
peroxide was studied. Results showed that the Pd@CeO2 catalyst
exhibited high catalytic activity in methane oxidation. Pd nanoparticles
were well stabilized by CeO2 shell encapsulation, resulting
in high stability of the catalyst. A high CH4 conversion
of 99% was retained after 50 h on-stream reaction at 500 °C.
Additionally, many tiny pores on the CeO2 shell surface
were beneficial for the full contact between reactants and active
components. Pd nanoparticles were highly dispersed inside the shell,
improving the utilization efficiency of active components. The results
also demonstrated that the Pd species in the catalyst existed in the
form of oxidation state, mainly in PdO (ca. 66.6%), which played an
essential part in methane combustion.