Heusler Alloys: A Group of Novel Catalysts

Abstract

In this study, we investigated the catalytic properties of various Heusler alloys for the hydrogenation of propyne and the oxidation of carbon monoxide. For propyne hydrogenation, Co 2 FeGe alloy showed a higher activity than that of elemental Co, where neither Fe nor Ge showed any activity. This clearly indicates an alloying effect. For the oxidation of carbon monoxide, although most alloys showed a significant change in catalytic activity during measurement due to an irreversible oxidation of the alloy, Co 2 TiSn alloy showed a very small change. The results indicate that the catalytic activity and stability of a Heusler alloy can be tuned by employing an appropriate set of elements.

The emergence of Heusler alloy catalysts

“…These results indicate that we can control an activity by choosing X and a durability by Y and Z. [11,12] The alloys listed in Table 1 were investigated for the hydrogenation of propyne (C 3 H 4 ) using a reactant of [1%C 3 H 4 /55%H 2 /He balance]. Figure 6 shows conversions of C 3 H 4 for catalysts with a total surface area of 0.027 m 2 .…”

“…3.1. Oxidation of carbon monoxide [11,12] The 12 Heusler alloys listed in Table 1 were investigated for the oxidation of carbon monoxide using a reactant of [1.2%CO/0.4%O 2 /He balance], the concentration of which was CO rich to suppress an irreversible oxidation of catalysts. Figure 4 shows conversions of CO during continuous heating by 2.5°C min -1 .…”

“…Horizontal line at 66.7% is a guide for describing the maximum conversion calculated from the CO:O 2 ratio. After Ref [11], reproduced with permission by ACS, https://pubs.acs. org/doi/10.1021/acsomega.6b00299.…”

“…Details are described in the previous papers [5,11,12]. Alloy ingots were prepared by arcmelting from pure metallic pieces (purity ≥ 99.9%).…”

“…Especially, they have attracted attention of magnetic researchers since the discovery of Cu 2 MnAl over a century ago [9,10] because they display ferromagnetism without ferromagnetic elements. Focusing on these features, we started a study on Heusler alloys as new catalysts, and experimentally investigated their catalytic properties [11,12]. In this study, we roughly revealed the catalytic properties of Heusler alloys by investigating 12 alloys for the hydrogenation of propyne and the oxidation of carbon monoxide.…”