Highly dispersive palladium nanoparticle in nanoconfined spaces for heterogeneous catalytic reduction of anthropogenic pollutants

Abstract

Pd-containing catalysts are highly promising in catalytic reactions, and their activity severely dependent on the dispersion extent of Pd nanoparticles (Pd NPs) . However, the regulation of Pd NPs size and dispersion degree are now pretty much the agendas. Here we report a facile solid-state fabrication strategy (SSFS) to promote Pd NPs dispersion in the nano environment of as made mesoporous silica KIT-6 (AK) by taking advantage of three critical factors, namely (i) the confined spaces where Pd precursor locate during fabrication, (ii) the interaction between Pd and supports, and (iii) the 3-dimentional (3D) structure of AK. First, AK presents 3D confined spaces between silica walls and template P123. Second, both silica walls and template P123 in AK offer interaction with Pd precursor. Third, the 3D structure provides more easy access for Pd insertion than linear channels structure without any pore blockage. The characterization results revealed that AK give better dispersion with smaller size of (3.9 nm) Pd than its counterpart (16 nm) prepared from template-free KIT-6 (CK). Moreover, the synthesized catalysts exhibit excellent activity and stability in catalytic conversion of p-nitrophenol (p-NP) and Methylene blue (MB). For a typical PdAK-1.0 catalyst, the complete conversion of P-NP and MB was achieved in less than 10 min with a reaction rate constant (k) of 0.3106 and 0.345 min^-1, respectively. It is superior to that on PdCK-1.0 prepared from template free KIT-6 and several reported catalysts. Furthermore, the PdAK-1.0 catalyst presents pretty good stability in catalytic reduction and is apparently better than PdCK-1.0.

Keywords: 3-D nano environment; Catalytic reactions; KIT-6; Pd nanoparticles; Solid-state fabrication strategy.