Strategies for improving the activity of catalysts based on vanadium oxides prepared by various methods for application in oxidation reactions

• Grant number: 19/17156-0
• Support Opportunities: Regular Research Grants
• Start date: July 01, 2020
• End date: December 31, 2022
• Field of knowledge: Engineering - Chemical Engineering - Chemical Technology
• Principal Investigator: Leandro Pierroni Martins
• Grantee: Leandro Pierroni Martins
• Host Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

Mixed oxides based on vanadium and molybdenum are prominent catalysts for performing oxidation reactions due to the oxidative potential of vanadium in these structures. Catalytic oxidation is under constant study and the mechanism is primarily due to the redox cycle: creation of surface vacancies of oxygen and consequent rearrangement of oxygen atoms through the oxide structure to provide the active site of the catalyst. In spite of the exceptional industrial application in oxidation reactions, these catalysts have very low textural properties, such as low specific areas and low porosity and instability of the mixed oxide phases under reaction conditions, with the transformation of active phases to other structures and morphologies that are less active. These transformations, with consequent deactivation of the catalyst, can occur when the catalysts are applied in systems with high temperatures and oxidizing atmospheres. In this case the formation of monocomponent metal oxides and/or migration of active species to amorphous phase occurs. In order to be more efficiently used in oxidation reactions, the properties of such catalysts need to be improved, not only the stability of phases but also the enhancement of the redox cycle that can be tuned by changes in the morphology and porous structure of the material (meso/macropores) with increasing active surface area. We conducted a preliminary appraisal by synthesizing MoxVyOz oxides using sodium dodecylsulfate as a surfactant in the hydrothermal treatment; it was generated significant transformations in the morphology, crystalline structure, and surface area that lead to an increased catalytic activity and stabilization of a few active phases, a behavior not reported before. Due to the potential of these catalysts, it is important to establish the structure-activity relationship of these new catalysts with the modifications in their structural and textural properties (porosity and surface area) induced by organic structure directing agents (SDA). Syntheses procedures under different conditions and using diverse SDA shall be investigated. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

VIEIRA, LUIZ H.; LOPEZ-CASTILLO, ALEJANDRO; JONES, CHRISTOPHER W.; MARTINS, LEANDRO. Exploring the multifunctionality and accessibility of vanadosilicates to produce acrylic acid in one-pot glycerol oxydehydration. APPLIED CATALYSIS A-GENERAL, v. 602, JUL 25 2020. (18/01258-5, 17/00860-0, 19/12501-0, 19/17156-0, 14/20116-6)