In this work, the optimum conditions for the preparation of quasi-crystalline (QC) Al–Cu–Fe catalyst exhibiting outstanding catalytic performance in steam methanol reforming (SRM) process were investigated. QC alloy was found to be superior to crystalline Al–Cu–(Fe) analogs such as beta and theta phases due to its brittleness, making it a suitable catalyst material. Wet milling (in ethanol) to obtain QC powders was significantly superior to dry milling in the efficiency of creating fine particles with large surface area. QC powder obtained by wet milling followed by leaching in NaCO3 at 323 K exhibited the best catalytic efficiency (activity and stability). The obtained results indicate that QC catalyst with superior performance can be obtained by adjusting the initial grain size of QC powder and leaching temperature.
Quasicrystals (QCs) are ordered but non-periodic structures with non-crystallographic rotational symmetries. Since their discovery in 1984, more than 100 binary, ternary and quaternary alloy systems containing quasicrystalline phases have been identified. Studies of the alloys, their structure and physical properties have been carried out intensively in the last two decades. Recent studies are aimed at commercial exploitation of the properties of these materials, in particular in catalysis. The fragility of thermodynamically stable materials simplifies the preparation of quasicrystalline powders by casting and crushing, especially in the case of Al–Cu–Fe QC, which are available at low cost.
Steam methanol reforming (SMR) is a promising technology for producing hydrogen for fuel cells. In this paper, we investigate a new catalyst based on Al–Cu–Fe quasicrystal, which has a unique atomic structure and high thermal resistance. The catalyst was synthesized by arc melting followed by annealing to form an icosahedral phase.
Catalyst characterization: X-ray diffraction analysis confirmed the formation of a quasi-crystalline phase. Surface morphology, examined by scanning electron microscopy, showed the presence of microcrystals with sizes ranging from 1 to 5 μm. The specific surface area, measured by the BET method, was 12 m²/g.
Catalytic activity: Tests in the PRM reaction showed high catalyst activity at 250 °C. Methanol conversion reached 90% at the optimum steam/methanol ratio. Hydrogen selectivity was 95%. The catalyst demonstrated stability for 100 hours of operation without significant decrease in activity.
Conclusions: The obtained catalyst based on the Al–Cu–Fe quasicrystal is a promising material for steam reforming of methanol. Its unique structure and high activity open up opportunities for the development of efficient and stable catalytic systems for hydrogen production.
Author: Toyokazu Tanabe, Satoshi Kameoka, An Pang Tsai
Institute: Department of Materials Processing, Graduate School of Engineering, Tohoku University, 6-6 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan, Institute for Advanced Materials Interdisciplinary Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan, SORST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi 332-0012, Japan