Humic Acid Modified Applied Palladium Catalysts for Nitro Compounds Reduction
Abstract
In this study, the feasibility of employing humic acids (HA) as natural polymer modifiers for palladium catalysts in practical applications was investigated. Furthermore, we synthesized novel catalysts comprising palladium-HA complexes immobilized on bauxite-094 (B-094) carriers and examined their catalytic capabilities in the reduction of p-nitrodiethylaniline (PNDA) and potassium o-nitrophinolate (PtONPh). Humic acid, a non-toxic, cost-effective, and readily available high-molecular-weight polymer, emerged as an attractive candidate for modifying applied palladium catalysts in nitro compound hydrogenation processes. This article presents research findings on the preparation of polymer-metal catalysts through various methods. Our investigations revealed that HA possesses enhanced acidity and sorption properties, as well as greater macromolecular branching and asymmetry. Additionally, we observed that the activity and stability of polymer-metallic complexes (PMCs)-based catalysts depend on the sequence of active phase application onto the carrier. Notably, the catalyst denoted as 1.0% Pd-HA (1.0%)/B-094 exhibited the largest specific surface area and demonstrated superior activity and stability in the reduction reactions of PNDA and PtONPh. Given that both HA (a polymer) and bauxite-094 (the carrier) are natural materials, the development of such catalysts is characterized by minimal economic costs, aligning with one of the primary requisites for modern catalysts.