Palladium Nanoparticle-Loaded Cellulose Paper: A Highly Efficient, Robust, and Recyclable Self-Assembled Composite Catalytic System

Abstract

We present a novel strategy based on the immobilization of palladium nanoparticles (Pd NPs) on filter paper for development of a catalytic system with high efficiency and recyclability. Oleylamine-capped Pd nanoparticles, dispersed in an organic solvent, strongly adsorb on cellulose filter paper, which shows a great ability to wick fluids due to its microfiber structure. Strong van der Waals forces and hydrophobic interactions between the particles and the substrate lead to nanoparticle immobilization, with no desorption upon further immersion in any solvent. The prepared Pd NP-loaded paper substrates were tested for several model reactions such as the oxidative homocoupling of arylboronic acids, the Suzuki cross-coupling reaction, and nitro-to-amine reduction, and they display efficient catalytic activity and excellent recyclability and reusability. This approach of using NP-loaded paper substrates as reusable catalysts is expected to open doors for new types of catalytic support for practical applications.

Halide-Enhanced Catalytic Activity of Palladium Nanoparticles Comes at the Expense of Catalyst Recovery

“…Shao et al [60] also describe a surface-based process, but one which depends on the palladium dynamics. We have similarly shown that cellulose paper-immobilised Pd NPs form a catalyst for C-C bond-forming reactions providing outstanding catalyst recovery and no detectable (by ICP MS) Pd leaching [26]. These findings similarly suggest that the reaction occurs on the nanoparticle surface.…”

“…reactions, the typically lower aqueous solubility of products compared to reactants can be used as an advantage, which we have shown for the SMXR where we achieved a pure product which crystallized directly from the predominantly aqueous reaction medium [26].…”

“…The challenge with using water as a solvent for palladium-catalysed reactions is that many palladium compounds and NPs are insoluble in water. For cross-coupling reactions, the typically lower aqueous solubility of products compared to reactants can be used as an advantage, which we have shown for the SMXR where we achieved a pure product which crystallized directly from the predominantly aqueous reaction medium [26].…”

“…The main concern with immobilised nanoparticles in catalysis is whether the nanoparticles remain bound to the support under reaction conditions, since any particles, ions, or atoms detached from the surface will not be recovered. We have previously demonstrated how palladium nanoparticles can be immobilized on polystyrene microspheres [25] and on cellulose paper [26].…”

Palladium Nanoparticles within Core-Cross-Linked Polymer Gels for Suzuki Coupling Reactions: from Monomers to Ready-to-Use Catalysts in Two-Steps

“…Considering this fact, we decided to test the possibility of catalyst recycling by applying the so-called "dip catalyst" strategy. [46][47][48][49] The dip catalyst preparation was carried out following a procedure adapted from the recent work of Zheng et al, 49 who used cellulose paper as substrate. In our study, the composite catalytic system was prepared by immersion of cellulose filter paper pieces (15 × 15 mm) in 6@PdNPs solutions (prepared as described in the Nanoparticle synthesis section), followed by vacuum drying for at least 24 h. This process was repeated three times.…”