Efficient and Selective Oxidation of Aromatic Amines to Azoxy Derivatives over Aluminium and Gallium Oxide Catalysts with Nanorod Morphology

Author(s)

Singh, Bhawan ^{[1, 2, 3]} ; Mandelli, Dalmo ^[1] ; Pescarmona, Paolo P. ^[2]

Affiliation

^[1] Fed Univ ABC, Ctr Nat & Human Sci, 5001 Av Estados Bangu, BR-09210580 Santo Andre, SP - Brazil

^[2] Univ Groningen, Engn & Technol Inst Groningen ENTEG, Chem Engn Grp, Nijenborgh 4, NL-9747 AG Groningen - Netherlands

^[3] Katholieke Univ Leuven, Ctr Surface Chem & Catalysis, Celestijnenlaan 200F, B-3001 Heverlee - Belgium

• Document type: Journal article
• Source: CHEMCATCHEM; v. 12, n. 2 OCT 2019.
• Web of Science Citations: 0

Abstract

Aluminium oxide and gallium oxide nanorods were identified as highly efficient heterogeneous catalysts for the selective oxidation of aromatic amines to azoxy compounds using hydrogen peroxide as environmentally friendly oxidant. This is the first report of the selective oxidation of aromatic amines to their azoxy derivatives without using transition metal catalysts. Among the tested transition-metal-free oxides, gallium oxide nanorods with small dimensions (9-52 nm length and 3-5 nm width) and fully accessible, high surface area (225 m(2) g(-1)) displayed the best catalytic performance in terms of substrate versatility, activity and azoxybenzene selectivity. Furthermore, the catalyst loading, hydrogen peroxide type (aqueous or anhydrous), and the amount of solvent were tuned to optimise the catalytic performance, which allowed reaching almost full selectivity (98 %) towards azoxybenzene at high aniline conversion (94 %). Reusability tests showed that the gallium oxide nanorod catalyst can be recycled in consecutive runs with complete retention of the original activity and selectivity. (AU)

• FAPESP's process: 18/01258-5 - Novel chemical catalytic and photocatalytic processes for the direct conversion of methane and CO2 to products
• Grantee: José Maria Correa Bueno
• Support Opportunities: Research Projects - Thematic Grants