Discerning the Metal Doping Effect on Surface Redox and Acidic Properties in a MoVTeNbO x for Propa(e)ne Oxidation

• Published in: ACS omega 2021-06, Vol.6 (23), p.15279-15291
• Main Authors: Quintana-Solórzano, Roberto, Mejía-Centeno, Isidro, Armendáriz-Herrera, Hector, Ramírez-Salgado, Joel, Rodríguez-Hernandez, Andrea, Guzmán-Castillo, Maria de Lourdes, Lopez Nieto, Jose M, Valente, Jaime S
• Format: Article
• Language: English
• ISSN: 2470-1343; 2470-1343
• DOI: 10.1021/acsomega.1c01591

Adding a small quantity of K or Bi to a MoVTeNbO x via impregnation with inorganic solutions modifies its surface acid and redox properties and its catalytic performance in propa­(e)­ne partial oxidation to acrylic acid (AA) without detriment to its pristine crystalline structure. Bi-doping encourages propane oxydehydrogenation to propene, thus enlarging the net production rate of AA up to 35% more. The easier propane activation/higher AA production over the Bi-doped catalyst is ascribed to its higher content of surface V leading to a larger amount of total V5+ species, the isolation site effect of NbO x species on V, and its higher Lewis acidity. K-doping does not affect propane oxydehydrogenation to propene but mainly acts over propene once formed, also increasing AA to a similar extent as Bi-doping. Although K-doping lowers propene conversion, it is converted more selectively to acrylic acid owing to its reduced Brønsted acidity and the presence of more Mo6+ species, thereby favoring propene transformation via the π-allylic species route producing acrylic acid over that forming acetic acid and CO x via acetone oxidation and that yielding directly CO x .