Porous
poly(ionic liquid)s (PPILs) combine the features of porous materials,
polymers, and ionic liquids (ILs) or their derivatives, but they are
normally of amorphous structure with disordered pores. Here, we report
the facile synthesis of ordered porous poly(ionic liquid) crystallines
(OPICs, specialized as a kind of PPIL analogues) with diverse and
adjustable framework IL moieties through the Schiff base condensation
of IL-derived ionic salts and neutral monomers. Ternary monomer mixtures
are employed to artistically control the chemical composition and
pore configurations. Compact atomic packing was achieved to give spacing
confined ionic surface with strong CO2 affinity. Through
monomer control, OPICs exhibit high CO2 uptakes with excellent
CO2/N2(CH4) selectivities and efficiently
implement CO2 fixation through catalyzing epoxides cycloaddition
under down to ambient conditions.
Carbon materials are promising environmentally-benign heterogeneous catalysts but design of effective carbon catalysts with comparable or even superior performance to metal-based ones is highly challengeable. Herein, N-doped mesoporous carbons with the surface enriched with abundant oxygen species were synthesized by a facile hydrothermal doping strategy in the self-assembly of phenolic resin, followed with a carbonization process. Direct hydroxylation of benzene to phenol with O 2 as the sole oxidant was effectively catalyzed by these carbons, affording a yield superior or comparable to previous efficient transition metal and even noble metal-based catalysts. The catalyst is facilely recovered and stably reused. The surface carbonyl groups are the active sites for O 2 activation (rate determining step) to generate hydroxyl radicals, which are the reactive oxygen species to oxidize the benzene. This methodology is readily extendable to the oxidation of various other benzene derivatives.[a] W.
Carbon-supported ferric oxide nanoparticles
(Fe2O3 NPs) were constructed via directly carbonizing
mesoporous
poly(ionic liquid) with [Fe(CN)6]3– anions,
which was prepared through the free-radical self-polymerization of
ionic liquid monomer 1-allyl-3-vinylimidazolium chloride in a soft-template
route and successive ion exchange with potassium ferricyanide. The
unique mesoporous ionic networks enabled the molecular dispersion
of ferric precursors and therefore resulted in highly dispersed Fe2O3 NPs on carbon. The catalyst exhibited high yield,
remarkable turnover number, and good reusability in the reductant-free
aerobic oxidation of benzene to phenol with O2. The synergistic
effect of Fe2O3 NPs and carbon accounted for
the high performance. This work delivered the first efficient and
environmentally friendly heterogeneous catalyst for reductant-free
benzene hydroxylation with O2.
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