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Cu–Zn–Al hydrotalcites as precursors of catalysts for the production of hydrogen from methanol
The possibility of a wide use of hydrogen as fuel of proton exchange membrane fuel-cells forces to the development of selective catalytic materials for the oxidative steam reforming of methanol (OSRM) to produce H 2 essentially free from CO. Cu/ZnO/Al 2O 3 catalysts of OSRM process have been obtaine...
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Published in: | Solid state ionics 2005-12, Vol.176 (39), p.2917-2922 |
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Main Authors: | , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that cite this one |
Online Access: | Get full text |
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Summary: | The possibility of a wide use of hydrogen as fuel of proton exchange membrane fuel-cells forces to the development of selective catalytic materials for the oxidative steam reforming of methanol (OSRM) to produce H
2 essentially free from CO. Cu/ZnO/Al
2O
3 catalysts of OSRM process have been obtained from hydrotalcite-like precursors with nominal formula Cu
1−
x−
y
Zn
y
Al
x
(OH)
2(CO
3)
x/2
(
x
=
0.23–0.42,
y
=
0.31–0.58) and prepared by homogeneous precipitation from metal chlorides solutions in the presence of urea. The catalysts were obtained after thermal decomposition of the hydrotalcites at 450 °C, followed by in situ reduction with H
2. X-ray powder diffraction (XRPD) patterns of the precursors showed the presence of the hydrotalcite phase with minor amounts of a Zn-rich paratacamite phase (Cu
2−
x
Zn
x
(OH)
3Cl) whose amount increases with increasing Cu content. XRPD patterns of thermally treated samples show only the lines of CuO and ZnO phases; Al
2O
3 and/or aluminates may be present as amorphous phases. The BET surface areas of the samples are in the range 110–220 m
2 g
−
1
and increase with increasing Al content. The catalytic activity in the OSRM process is appreciable from about 200–250 °C and methanol conversions up to 90–95% are obtained at temperatures of 300–400 °C. Hydrogen is the main product, and its yield reaches values up to 2.7 mol/mol of methanol. Carbon monoxide content is under the detection limit (500 ppm) of the detector. |
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ISSN: | 0167-2738 1872-7689 |
DOI: | 10.1016/j.ssi.2005.09.051 |