Abstract
In this study, the authors rationally designed a high-performance catalytic filter for continuous flow catalysis. The catalytic filter consisted of ligand-free nanoscale gold (nano-Au) catalysts and nitrogen-doped graphene (N-rGO). The Au catalyst was fabricated in situ onto a pre-formed N-rGO support by the NaBH4 reduction of the Au precursor, and the size of the nano-Au was fine-tuned. A hydrothermal pretreatment of graphene oxide enriched nitrogen-containing species on the surface of two-dimensional graphene supports and enhanced the affinity of Au precursors onto the support via electrocatalytic attraction. The nano-Au catalysts acted as high-performance catalysts, and the N-rGO acted as ideal filter materials to anchor the catalysts. The catalytic activity of the as-designed catalytic filter was evaluated using 4-nitrophenol (4-NP) hydrogenation as a model catalytic reaction. The catalytic filters demonstrated superior catalytic activity and excellent stability, where a complete 4-nitrophenol conversion was readily achieved via a single pass through the catalytic filter. The as-fabricated catalytic filter outperformed the conventional batch reactors due to evidently improved mass transport. Some key operational parameters impacting the catalytic performance were identified and optimized. A similar catalytic performance was also observed for three 4-nitrophenol spiked real water samples (e.g., surface water, tap water, and industrial dyeing wastewater). The excellent catalytic activity of the nano-Au catalysts combined with the two-dimensional and mechanically stable graphene allowed for the rational design of various continuous flow catalytic membranes for potential industrial applications.
Highlights
Noble metal nanoparticles have been extensively explored for application in catalysis [1,2,3,4,5]
Transforming the unique characteristics of individual nanoscale components into macroscopic materials such as membranes or sheets remains a challenge, as the engineering of these structures often compromises their intrinsic properties [32]. For this contribution to research, ligand-free nanoscale gold catalysts with a tunable size were grown in situ onto a nitrogen-doped graphene (N-rGO) support membrane for continuous flow catalysis applications
The Au/N-rGO catalytic filters were fabricated by the in situ reduction of gold salt
Summary
Noble metal nanoparticles have been extensively explored for application in catalysis [1,2,3,4,5]. A more promising design is to construct a catalytic membrane reactor by integrating the catalytic nanoparticles with a desirable membrane material [29] These nanoscale catalysts can be effectively immobilized onto or into a support matrix without inhibiting access to catalytic sites [30]. Transforming the unique characteristics of individual nanoscale components into macroscopic materials such as membranes or sheets remains a challenge, as the engineering of these structures often compromises their intrinsic properties [32] For this contribution to research, ligand-free nanoscale gold (nano-Au) catalysts with a tunable size were grown in situ onto a nitrogen-doped graphene (N-rGO) support membrane for continuous flow catalysis applications. A few 4-NP spiked real water samples were challenged with the catalytic filter
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