Addition of Zn into NiOx nanocluster supported on Al₂O₃ and its activity toward aerobic oxidation of 1-phenylethanol.

抄録

The oxidation of alcohols to aldehydes or ketones is an essential chemical process. For this reaction, noble metals such as Au [1] and Pd [2] have been reported as highly efficient catalysts. However, noble metals are expensive and not abundant. To solve these problems, development of noble metal substitute catalyst is strongly desired. In this work, Ni, which has advantages of costs and availability over noble metals, is focused on as an active component. To improve the catalytic activity of Ni, two techniques were introduced, the one is nanoclusterization and the other is addition of second element. Zn modified NiOx nanocluster was prepared by colloidal method using polyvinylpyrrolidone (PVP) and NaBH₄ as a stabilizer and reducing agent, respectively. Obtained colloid was poured into Al₂O₃ support under N₂ atmosphere to support it. After immersing it, washed by distilled water to form NiOx nanoclusters on Al₂O₃. Prepared NiOx nanocluster catalyst showed extremely high catalytic activity compared to bulk Ni(OH)₂ as shown in Table 1. Addition of Zn into NiOx nanoclusters improved the catalytic activity. Only addition of 5.3% Zn relative to Ni improved the acetophenone yield from 40% to 53%. X-ray absorption fine structure (XAFS) analysis revealed that the Ni species with high oxidation state was generated in the catalyst matrix by the addition of Zn as shown in Fig. 1. Catalysis will be explained in terms of Zn and Ni local structure.

References

[1] E. Pakrieva et al., Nanomaterials 10, 151 (2020).[

2] Y. Lu, H. Zhu, J. Liu and S. Yu, ChemCatChem 7, 4131 (2015).