Hydrothermal Fabrication and Catalytic Properties
of YBa
2
Cu
3
O
7
Single Crystallites for Methane Combustion
Yue Zhang
•
Lei Zhang
•
Jiguang Deng
•
Hongxing Dai
•
Hong He
Received: 23 October 2009 / Accepted: 29 November 2009 / Published online: 5 January 2010
Ó Springer Science+Business Media, LLC 2009
Abstract The YBa
2
Cu
3
O
7
nano/microsized single crys-
tallites with spherical and rod-like morphologies were fab-
ricated hydrothermally. The catalytic performance of the
materials was evaluated for methane combustion. It is shown
that there was a clear relationship between the a-oxygen
desorption or initial H
2
consumption rate and catalytic
activity. The single-crystalline perovskite-like cuprate cat-
alysts outperformed the polycrystalline counterpart. The
good catalytic performance of the hydrothermally derived
YBa
2
Cu
3
O
7
single crystallites is associated with more
a-oxygen adspecies, better low-temperature reducibility,
high-quality single crystallinity, and unique morphology.
Keywords Perovskite-like oxide catalyst Á
Single crystalline YBa
2
Cu
3
O
7
Á Hydrothermal synthesis Á
Specific morphologies Á Methane combustion
1 Introduction
In the past decades, a large number of materials, such as
noble metals, transition metal oxides, and mixed oxides
(e.g., perovskite-type oxides, perovskite-like oxides, and
hexaaluminate [1–3]), have been tested as catalyst for the
combustion of light hydrocarbons. Although supported
PdO catalysts have been believed to perform the best for
methane combustion [4], such materials are expensive and
suffer from drastic deactivation at high temperatures
([700 °C) due to sintering [3], hence limiting their
extensive applications. Among the base metal-based cata-
lysts, perovskite-type and perovskite-like oxides show
promising performance in catalyzing the oxidation of
methane. The latter possesses higher thermal stability than
former [5, 6], and show good catalytic activities for the
total oxidation of carbon monoxide [7, 8], propane [7], and
methane [9].
YBa
2
Cu
3
O
7
(YBCO) is a high temperature supercon-
ductor with an orthorhombic triple-layered perovskite-type
structure. Various methods, such as the precursor com-
bustion [10], sol–gel [11], biopolymer templating [12], and
anodic aluminum oxide (AAO) templating techniques [13,
14], have been adopted to prepare YBCO superconductors.
This perovskite-like oxide shows good catalytic perfor-
mance for the hydrogenation of CO or CO
2
to methanol
[15–17], the oxidation of methane [18, 19], and the
decomposition of N
2
O[20]. The perovskite-type and
perovskite-like oxides prepared by means of the above
methods are usually polycrystalline. In recent years, single
crystalline perovskite-type and perovskite-like oxides have
been fabricated using hydrothermal treatment strategies,
and applied for the catalysis of carbon monoxide and
methane [21]. The catalytic performance of these single
crystallites is proven to be superior to that of their poly-
crystalline counterparts [22]. Therefore, it is highly desired
to investigate the fabrication and catalytic properties of
perovskite-related oxides with single crystalline structures
for the combustion of hydrocarbons.
Hydrothermal synthesis is a recently developed effec-
tive technique for the preparation of nano/micrometer
multi-component oxides at low temperatures [23]. The
hydrothermal conditions, such as precursor nature and
concentration, pH value, temperature, and time, have sub-
stantial effects on the crystal structure and morphology of
Y. Zhang Á L. Zhang Á J. Deng Á H. Dai (&) Á H. He
Laboratory of Catalysis Chemistry and Nanoscience,
Department of Chemistry and Chemical Engineering, College of
Environmental and Energy Engineering, Beijing University of
Technology, 100124 Beijing, People’s Republic of China
e-mail: hxdai@bjut.edu.cn
123
Catal Lett (2010) 135:126–134
DOI 10.1007/s10562-009-0245-z