One-Pot Aqueous and Template-Free Synthesis of Mesoporous Polymeric Resins

Mahboubeh Nabavinia,Peter Kerns,Philip Wall,Joseph Stanzione,Alireza Shirazi Amin,Iman Noshadi,Fujian Liu,Baishali Kanjilal,Alexander Hesketh,Steven Suib

doi:10.3390/catal9090782

Mahboubeh Nabavinia, Peter Kerns + Show 8 more

Open Access

https://doi.org/10.3390/catal9090782

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Abstract

This work explores the novel one-pot aqueous phase synthesis of mesoporous phenolic-hyperbranched polyethyleneimine resins without the use of a template, and their utility as heterogeneous catalysts in batch reactors and continuous microreactors. Catalyst surface areas of up to 432 m2/g were achieved with a uniform Pd distribution and an interconnected, highly porous, network structure, confirmed through Brunauer–Emmett–Teller (BET) surface area measurements, scanning electron microscopes (SEM), X-Ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), and Energy-dispersive X-ray spectroscopy (EDS). The heterogeneous catalysts achieved a maximum 98.98 ± 1% conversion in batch Suzuki couplings, with conversions being dependent upon reaction conditions, reactant chemistries, Pd loading and catalyst surface area. The catalysts were shown to be recyclable with only a marginal loss in conversion achieved after five runs. Up to 62 ± 5% and 46.5 ± 8% conversions at 0.2 mL/s and 0.4 mL/s flow rates, respectively, were achieved in a continuous microreactor. Understanding the mechanism of action of this mesoporous resin is a future research area, which could help expand the application vistas for this catalyst platform.

Highlights

Research interest in the subject of mesoporous polymeric resins (MPRs) is ongoing and extensive, with their applications spanning selective adsorption and water treatment, separation and insulation, and the field of heterogeneous catalysis [1,2,3,4,5,6,7,8,9,10,11,12]
The Brunauer–Emmett–Teller (BET) surface area was calculated based on N2 adsorption isotherms (Table 1)
We evaluated the effect of palladium concentration on the surface area of the Pd-MPRs (Figure 1b)

Summary

Introduction

Research interest in the subject of mesoporous polymeric resins (MPRs) is ongoing and extensive, with their applications spanning selective adsorption and water treatment, separation and insulation, and the field of heterogeneous catalysis [1,2,3,4,5,6,7,8,9,10,11,12]. MPRs proffer intrinsic characteristics such as tunable structures with tailorable mesopores size (2–30 nm) [13,14,15,16,17,18,19,20,21]. These are distinct advantages when compared to porous organic polymers entailing crystalline covalent organic or aromatic frameworks, conjugated microporous polymers or mesoporous polydivinylbenzene. Structures are more accessible to substrates and provide superior catalytic activity. MPRs can be directly carbonized to ordered mesoporous carbons in a cost-effective manner [1,2,3,11,21,22,23,24].

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