NASICON Catalysts with Composition Na(Cs)1 – 2xMxZr2(PO4)3 for Transformations of Aliphatic Alcohols

Abstract: The activity of solid electrolytes from the family of Na(Cs)–Mx–Zr phosphates (NZP and CZP) with dopant ions M+2 = Co+2 and Ni+2 synthesized by the sol–gel method is studied in the gas-phase transformations of isopropanol and isobutanol. It is found that the amount of M+2 and its nature, as well as the direction of a change in the catalyst temperature (heating or cooling in the range of 473−693 K), affects the activity of M-NZP and M-CZP. In the transformation of isopropanol, hysteresis of the acetone yield, counter-clockwise (type I) for Co-NZP and clockwise (type II) for Ni-NZP, is observed in the heating–cooling cycles. An increase in the activity of Co-NZP in the cooling mode (type I) is related to a rise in the apparent activation energy of alcohol dehydrogenation under conditions of the formation of new catalytically active sites in the form of a Co+2−Zr+4 → Co+3−Zr+3 ion pair with the oxidized form of M and the reduced form of Zr. Type I hysteresis of the total alcohol conversion is observed in the transformations of isobutanol to olefin and aldehyde over Co(Ni)-CZP. The hysteresis is associated with a decrease in the activation energy of alcohol dehydrogenation. The main reaction over the Co(Ni)-CZP catalysts is the dehydration of alcohol with an increase in the activation energy of the reaction upon cooling, for example, by 53 kJ/mol for Ni0.25-CZP. © 2020, Pleiades Publishing, Ltd.

Журнал
Номер выпуска
10
Язык
Английский
Страницы
1176-1183
Статус
Опубликовано
Том
60
Год
2020
Организации
  • 1 Peoples’ Friendship University of Russia, Moscow, 117198, Russian Federation
Ключевые слова
catalytic activity; cobalt; complex zirconium orthophosphates; dehydrogenation and dehydration of alcohol; dopant cations; isobutanol; isopropanol; nickel; sol–gel synthesis; thermal hysteresis
Дата создания
02.11.2020
Дата изменения
02.11.2020
Постоянная ссылка
https://repository.rudn.ru/ru/records/article/record/64344/