Palladium Decorated, Amine Functionalized Ni-, Cd- and Co-Ferrite Nanospheres as Novel and Effective Catalysts for 2,4-Dinitrotoluene Hydrogenation

• Published in: International journal of molecular sciences Vol. 23; no. 21; p. 13197
• Main Authors: Hajdu, Viktória, Sikora, Emőke, Kristály, Ferenc, Muránszky, Gábor, Fiser, Béla, Viskolcz, Béla, Nagy, Miklós, Vanyorek, László
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-11-2022; MDPI
• Subjects: 2,4-Diaminotoluene; Aqueous solutions; Cadmium; Carbon; Catalysis; Catalysts; Catalytic activity; Cobalt; Cobalt ferrites; ferrite; Heavy metals; Hydrogenation; Industrial applications; Leaching; magnetic catalyst; Metal oxides; Nanoparticles; Nanospheres; nanostructure; Nickel ferrites; Noble metals; Palladium; Particle size; Polyurethane; Polyurethane resins; Precious metals; Selectivity; Separation; Sonochemical reactions; TDA
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms232113197

2,4-diaminotoluene (TDA) is one of the most important polyurethane precursors produced in large quantities by the hydrogenation of 2,4-dinitrotoluene using catalysts. Any improvement during the catalysis reaction is therefore of significant importance. Separation of the catalysts by filtration is cumbersome and causes catalyst loss. To solve this problem, we have developed magnetizable, amine functionalized ferrite supported palladium catalysts. Cobalt ferrite (CoFe2O4-NH2), nickel ferrite (NiFe2O4-NH2), and cadmium ferrite (CdFe2O4-NH2) magnetic catalyst supports were produced by a simple coprecipitation/sonochemical method. The nanospheres formed contain only magnetic (spinel) phases and show catalytic activity even without noble metals (palladium, platinum, rhodium, etc.) during the hydrogenation of 2,4-dinitrotoluene, 63% (n/n) conversion is also possible. By decorating the supports with palladium, almost 100% TDA selectivity and yield were ensured by using Pd/CoFe2O4-NH2 and Pd/NiFe2O4-NH2 catalysts. These catalysts possess highly favorable properties for industrial applications, such as easy separation from the reaction medium without loss by means of a magnetic field, enhanced reusability, and good dispersibility in aqueous medium. Contrary to non-functionalized supports, no significant leaching of precious metals could be detected even after four cycles.