Optimization of the performance of bulk NiO catalyst in the oxidative dehydrogenation of ethane by tuning the synthesis parameters

Highly stable and selective bulk NiO catalysts have been synthesized for the oxidative dehydrogenation (ODH) of ethane to ethylene. Interestingly, by optimizing synthesis parameters such as the amount of oxalic acid in the synthesis gel and the calcination temperature, undoped NiO catalysts have shown a consistent selectivity to ethylene of ca. 75%. The optimal catalyst requires the presence of a certain amount of oxalic acid in the synthesis gel and a final calcination at low temperatures (i.e. 350 degrees C). These catalysts have been deeply characterized by means of XRD, TPR, HRTEM, Raman and UV-vis diffuse reflectance spectroscopies, XPS and Electrochemical Impedance Spectroscopy measurements and tested in the ethane ODH. A novel electrochemical study has been undertaken, showing the p-character of all the NiO catalysts synthesized but differing in their capacitance values and density of cationic vacancies. The catalytic performance of NiO catalysts has been explained in terms of the different physicochemical properties (including changes in the number of vacancies) of the samples and the isolation of electrophilic oxygen species.

Automated summary

Highly stable and selective bulk NiO catalysts have been synthesized for the oxidative dehydrogenation of ethane to ethylene. The optimal catalyst requires the presence of oxalic acid in the synthesis gel and calcination at low temperatures. The catalytic performance has been explained by the different physicochemical properties and isolation of oxygen species.