Flow-Through PolyHIPE Silver-Based Catalytic Reactor

Abstract

Catalytic reactors performing continuously are an important step towards more efficient and controllable processes compared to the batch operation mode. For this purpose, homogenous high internal phase emulsion polymer materials with an immobilized silver catalyst were prepared and used as a continuous plug flow reactor. Porous material with epoxide groups was functionalized to bear aldehyde groups which were used to reduce silver ions using Tollens reagent. Investigation of various parameters revealed that the mass of deposited silver depends on the aldehyde concentration as well as the composition of Tollens reagent. Nanoparticles formed on the pore surface showed high crystallinity with a cuboctahedra crystal shape and highly uniform surface coverage. The example of the 4-nitrophenol catalytic reduction in a continuous process was studied and demonstrated to be dependent on the mass of deposited silver. Furthermore, productivity increased with the volumetric silver density and flow rate, and it was preserved during prolonged usage and storage.

Emulsion Templated Porous Poly(thiol-enes): Influence of Photopolymerisation, Emulsion Composition, and Phase Behaviour on the Porous Structure and Morphology

“…The most commonly utilised methods of stabilisation include surfactants, usually non-ionic ones and particles. The porous, cellular topology of polyHIPEs is advantageous for many applications of the materials, e.g., biomedical applications [ 5 , 6 ], as catalytic support [ 7 , 8 ], or separation and purification [ 9 ].…”

Tubular Catalytic Polyhipe Reactor with Deposited Silver Nanoplate Nanoparticles

“…PolyHIPE monoliths with a matrix volume of approximately 0.5 ml were prepared and characterized for permeability and open porosity as described elsewhere [11,21]. Briefly, the epoxy groups of the polyHIPE polymer were converted to quaternary amine (QA) ionizable functional groups with a basic aqueous solution of TMAHC [71].…”

“…The catalytic activity of the deposited silver nanoplates was determined according to the literature [11]. Briefly, a solution of 0.4 mM 4-NP, 60 mM NaBH 4 and 0.1 M NaOH with pH 13 to prevent NaBH 4 decomposition [82] and degassed to prevent oxidation of the intermediates [83].…”

“…The combination of catalyst nanoparticles with an inert porous matrix seems to be the method of choice to prepare highly permeable catalytic reactors while minimizing the amount of required catalyst. There are several approaches to construct such catalytic reactors, either by in situ catalyst synthesis [5][6][7][8][9][10][11][12] or by depositing already pre-synthesized NP and stabilizing them by various interactions [13][14][15].…”

“…Most of the polyHIPE pore surface area suitable for catalyst deposition is located within the large void pores [1,19,20], while the pressure drop has been shown to be mainly governed by the smaller interconnecting pores [21]. During in situ synthesis, silver nanoparticles (AgNP) are uniformly formed over the entire pore surface [11], including the interconnecting pores. Therefore, deposition of nanoparticles appears to be a better option, especially when loaded in a flow-through manner.…”