Synergy between NiWO4 and chitosan for the development of catalysts for sulfide oxidation

Author(s)

Grasser, Giovanna A. ; Ribeiro, Lara K. ; Longo, Elson ; Assis, Marcelo

• Document type: Journal article
• Source: CATALYSIS TODAY; v. 444, p. 12-pg., 2025-01-15.

Abstract

In this work, catalysts based on composite films composed by chitosan with disordered NiWO4 (10, 20, and 40 % w/w) were synthesized for their application in the oxidation of sulfides to sulfones. The catalysts were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), optical profilometry, and contact angle measurements. Optimization of the catalytic conditions was performed using thioanisole as the standard molecule, resulting in optimal conditions of 50 degrees C, 1 h, 10 mg catalyst loading, 8 equivalents of H2O2 as oxidant, and acetonitrile as solvent. The results obtained were superior to those with crystalline NiWO4 (highly ordered), highlighting the crystallinity of the system as a key factor in the development of new catalysts. The catalyst exhibited high stability over successive catalytic cycles, and scaling up to 50 times was achieved. Additionally, the reaction scope showed good conversion for a variety of different sulfides, indicating the robustness of the catalyst. Analysis of the catalytic mechanism through scavenger tests and spectroscopic probes revealed that reactive oxygen species (ROS) are responsible for the oxidation of sulfides to sulfones. Furthermore, it was observed that the synergy between NiWO4 and chitosan is crucial for the effective generation of ROS in this reaction. (AU)

• FAPESP's process: 23/12399-7 - Influence of rare-earth doping on the BiVO4 photoanode structure for biomass degradation and fuel cells
• Grantee: Lara Kelly Ribeiro da Silva
• Support Opportunities: Scholarships in Brazil - Support Program for Fixating Young Doctors
• FAPESP's process: 22/09715-1 - Sulfide oxidation via chitosan-supported g-C3N4/NiWO4 composites
• Grantee: Giovanna de Amorim Grasser
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 13/07296-2 - CDMF - Center for the Development of Functional Materials
• Grantee: Elson Longo da Silva
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC