Metal nanoparticle–carbon nanotubes hybrid catalysts immobilized in a polymeric membrane for the reduction of 4-nitrophenol

Abstract

In this work, the synthesis of silver and copper nanoparticles and bimetallic silver-platinum and copper-platinum nanoparticles, in previously functionalized multi-walled carbon nanotubes (MWCNT), was carried out using the intermatrix synthesis for the charge of the first metal, and a galvanic replacement for the deposition of a second metal to form the bimetallic NPs. Well-controlled small size NPs were obtained as demonstrated by TEM, with a homogeneous distribution and mean particle diameters of ca. 2.9 nm. The hybrid MNPs/MWCNTs catalysts were characterized by FTIR, TEM and XPS. The metal content was determined by TGA and validated via FAAS. Thereupon, the metal-MWCNTs hybrid catalysts were incorporated into a polymeric membrane (PM) and characterized by SEM. The effects of the hybrid catalyst-polymeric support interactions and the role of the MNPs/MWCNTs/PM materials as heterogeneous catalysts were evaluated from the catalytic performance on the reduction of 4-nitrophenol as a model reaction. An apparent rate constant normalized by the metal content of 1706.7 s −1 mol −1 was achieved for the best system (Ag-PtNPs/MWCNTs/PMR) along with a decrease in the percentage of conversion from 95% (first cycle) to 80% (third cycle). Results indicated that the catalytic activity depends mainly on the MNPs size and the metal content in the catalyst. The catalytic activity of the MNPs/MWCNTs was only 3 times higher than for the MNPs/MWCNTs/PMs catalysts, with the former presenting the advantage of being easily recovered from the reaction medium, thus, demonstrating the capability to perform an efficient and sustainable process.

Bimetallic Fe–Cu metal organic frameworks for room temperature catalysis

“…However, increasing the amounts of NaBH 4 and time led to the exclusive formation of only o-, m-, p-phenylenediamine product in excellent yields. The rates of the catalytic reduction for the three isomers of o-, m-, p-nitroaniline were also tested (Table 2, entries [12][13][14]. Results showed that the following rate order was 3-nitroaniline > 4-nitroaniline > 2-nitroaniline.…”

“…industrial formulations including pharmaceuticals, leather, dying, insecticides, plastic, fungicides, pesticides and paper industries, [6][7][8][9][10][11][12][13][14][15][16] are potentially toxic, mutagenic, teratogenic, carcinogenic, [17][18][19] and dangerous to human health. Among them, nitrophenols (NP) are considered as hazardous organic contaminants that have gradually increased in wastewater as manufactured from agricultural and industrial products, [20][21][22][23] and because of their great bioaccumulation and stability, they are stored for a long time in an environment with high carcinogenicity and toxicity.…”

Enhanced performance of glycerol electro-oxidation in alkaline media using bimetallic Au–Cu NPs supported by MWCNTs and reducible metal oxides

“…To increase the efficiency of CNTs as support, strategies based on the functionalization of the external surface area have been implemented. These strategies primarily consist of the introduction of oxygenated functionalities, mostly carboxylic, nitro, and sulfonic groups, in the walls of CNTs ( Wang et al, 2010 ; Esquivel-Peña et al, 2019 ). The second most studied supports are metal oxides because of their ability to provide oxygenated species to oxidize adsorbed intermediates.…”

Porous carbon‐supported CoPd nanoparticles: High‐performance reduction reaction of nitrophenol

“…[ 20–23 ] Therefore, several catalysts, which offer high efficiency and recyclability, have been designed for this proper transformation. [ 1–3,5,6b,7,24,25 ] Recently, new types of heterogeneous catalysts for reducing NP reactions have received considerable attention because of their useful and unique catalytic performance, high stability and reusability, and mild reaction conditions. Compared with conventional and widely used Pd homogeneous catalysts, Pd‐doped heterogeneous catalysts come to the fore much more in terms of the benefits and efficiency they provide.…”