Cation distribution in Zn–Cr spinel structure and its effects on synthesis of isobutanol from syngas: Structure–activity relationship

• The change of cation distribution of catalyst is investigated in quantitatively.
• The cation distribution of catalyst depends on annealed temperature and Zn/Cr molar ratio.
• The isobutanol productivity is related to the level of cation distribution of catalyst.

A series of Zn–Cr oxides nanoparticles with different degrees of cation disorder distribution were obtained by a coprecipitation and postcalcined method. Some qualitative analysis, such as Transmission Electron Microscope (TEM), Powder X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were used to confirm the structure of Zn–Cr oxides and the existence of cation disorder distribution. Meanwhile, the Rietveld method was used to quantitatively investigate the changes of cation distribution between tetrahedral and octahedral vacancies of different catalysts. The results demonstrated that the degree of cation disorder distribution became higher with decreasing annealing temperature and increasing the molar ratio of Zn–Cr. Furthermore, the level of cation disorder distribution in Zn–Cr spinel structure affects tremendously both texture parameters and acid–base properties of catalysts which make isobutanol generation more effectively. Most importantly, we first discover that the isobutanol productivity presents approximately linear relationship to the level of cation disorder distribution of Zn–Cr spinel in quantitatively, unambiguously revealing the structure–activity relationship between the activity of isobutanol and the structure of Zn–Cr spinel.

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