Nitrogen-Rich Porous Organic Polymers with Supported Ag Nanoparticles for Efficient CO2 Conversion

Abstract

As CO2 emissions increase and the global climate deteriorates, converting CO2 into valuable chemicals has become a topic of wide concern. The development of multifunctional catalysts for efficient CO2 conversion remains a major challenge. Herein, two porous organic polymers (NPOPs) functionalized with covalent triazine and triazole N-heterocycles are synthesized through the copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) reaction. The NPOPs have an abundant microporous content and high specific surface area, which confer them excellent CO2 affinities with a CO2 adsorption capacity of 84.0 mg g−1 and 63.7 mg g−1, respectively, at 273 K and 0.1 MPa. After wet impregnation and in situ reductions, Ag nanoparticles were supported in the NPOPs to obtain Ag@NPOPs with high dispersion and small particle size. The Ag@NPOPs were applied to high-value conversion reactions of CO2 with propargylic amines and terminal alkynes under mild reaction conditions. The carboxylative cyclization transformation of propargylic amine into 2-oxazolidinone and the carboxylation transformation of terminal alkynes into phenylpropiolic acid had the highest TOF values of 1125.1 and 90.9 h−1, respectively. The Ag@NPOP-1 was recycled and used five times without any significant decrease in catalytic activity, showing excellent catalytic stability and durability.

Effective CO2 Catalytic Conversion by Nitrogen-Rich Covalent Organic Framework-Immobilized Ag Nanoparticles

“…The Ag content in Ag/Aza-COF was then detected by inductively coupled plasma (ICP) spectroscopy analysis, and the result is 2.5%. Thus, the turn over frequency (TOF) value of Ag/Aza-COF is 24.2 h –1 , which is comparable with some reported Ag-based catalysts, , while the TOF value of Ag/CTAB is only about 0.48 h –1 . SEM and TEM measurements were also employed to detect the morphology of the prepared Ag/CTAB composite for analyzing the cause.…”

“…In order to reduce such an aggregation, surfactants, such as hexadecyl trimethylammonium bromide (CTAB) and polyvinylpyrrolidone (PVP), have been widely used in reactions involving nanometal catalysts, but their effectiveness is always unsatisfactory due to often raising suspicions of leaching . Porous materials have also been emerging as a group of nanocatalyst carriers not only because their cavities limit the aggregation of nanocatalysts but also because their porosity allows substrates to reach catalytic sites effectively. – Recently, covalent organic frameworks (COFs), a class of porous organic polymers with crystalline and periodic structures, have displayed as a group of very promising porous materials in wide applications. , As porous materials composed of organic components with light elements, such as C, H, O, and N, though covalent bonds, COF materials not only show low density and relatively high stability but also possess chemical tenability, i.e., can be covalently decorated by functional groups. – Therefore, selecting or constructing a COF with functionalized groups to embed an effective nanocatalyst has become a feasible way to fabricate efficient nanocatalyst composites for CO 2 conversion.…”

Conjugated Microporous Polymers for Catalytic CO2 Conversion

“…Moreover, the availability of commercially accessible alkynyl carboxylic acids is limited, thus novel approaches to synthesizing these compounds, such as the chemical conversion of CO 2 , have garnered significant interest. [116] In a recent investigation carried out by Wu et al, [103] two materials were designed and synthesized that exhibited catalytic performance in both the carboxylation of terminal alkynes (Table 3, Entry 3, up to 94% yield) and the carboxylative cyclization of propargylic amines with CO 2 with yields of up to 97% (Table 3, Entry 4; Scheme 4-B1). The catalytic efficacy can be attributed to several factors: a) Ag@NPOPs incorporates two distinct types of nitrogen heterocycles, specifically triazine and triazole rings.…”

A Triazole‐Based Covalent Gel Loaded with Cu/Pd Bimetallic Nanoparticles for Efficient Catalytic Cross‐Coupling Reactions

“…[21] Compared with homogeneous catalytic reactions which are difficult to separate residue catalysts, heterogeneous catalytic reactions are more environmentally friendly and resourceefficient with easy separation and fast reaction kinetics and mass transfer processes. [22] Various porous materials with specific structures have been used as supports, including carbon material, [23,24] silicon dioxide, [25,26] zeolites, [27,28] MOFs, [29,30] COFs, [31,32] POPs, [33,34] and gels. [35][36][37] Gels possess hierarchical pore structure, providing micropores for anchoring the catalytic center and macropores for efficient mass transfer.…”