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Impact of the Oxygen Defects and the Hydrogen Concentration on the Surface of Tetragonal and Monoclinic ZrO 2 on the Reduction Rates of Stearic Acid on Ni/ZrO 2
Author(s) -
Foraita Sebastian,
Fulton John L.,
Chase Zizwe A.,
Vjunov Aleksei,
Xu Pinghong,
Baráth Eszter,
Camaioni Donald M.,
Zhao Chen,
Lercher Johannes A.
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201405312
Subject(s) - stearic acid , catalysis , hydrodeoxygenation , chemistry , hydrogen , oxygen , reactivity (psychology) , adsorption , inorganic chemistry , monoclinic crystal system , hydrogen atom abstraction , decarbonylation , medicinal chemistry , organic chemistry , crystal structure , medicine , alternative medicine , pathology , selectivity
The role of the specific physicochemical properties of ZrO 2 phases on Ni/ZrO 2 has been explored with respect to the reduction of stearic acid. Conversion on pure m ‐ZrO 2 is 1.3 times more active than on t ‐ZrO 2 , whereas Ni/ m‐ ZrO 2 is three times more active than Ni/ t‐ ZrO 2 . Although the hydrodeoxygenation of stearic acid can be catalyzed solely by Ni, the synergistic interaction between Ni and the ZrO 2 support causes the variations in the reaction rates. Adsorption of the carboxylic acid group on an oxygen vacancy of ZrO 2 and the abstraction of the α‐hydrogen atom with the elimination of the oxygen atom to produce a ketene is the key to enhance the overall rate. The hydrogenated intermediate 1‐octadecanol is in turn decarbonylated to heptadecane with identical rates on all catalysts. Decarbonylation of 1‐octadecanol is concluded to be limited by the competitive adsorption of reactants and intermediate. The substantially higher adsorption of propionic acid demonstrated by IR spectroscopy and the higher reactivity to O 2 exchange reactions with the more active catalyst indicate that the higher concentration of active oxygen defects on m ‐ZrO 2 compared to t ‐ZrO 2 causes the higher activity of Ni/ m ‐ZrO 2 .