Synergistic Catalysis of Co‐Zr/CN_x Bimetallic Nanoparticles Enables Reductive Amination of Biobased Levulinic Acid

Abstract

Bimetallic synergy and carbon–nitrogen doping can contribute to enhanced catalytic activity due to the strong electronic state and unique geometrical structure. In this work, a series of biomass‐derived Co‐M bimetallic CN doped catalysts (Co‐M@Chitosan‐X; M = Zr, Ni, Fe, Cu, In; X denotes the molar percentage of M) are prepared via simple oil bath reflow and annealing. The Co‐Zr@Chitosan‐X catalysts are determined to contain alloys (Co‐Zr), metal‐carbon bonds (Co‐C, Zr‐C), metal‐nitrogen bonds (Co‐N, Zr‐N), and metal oxides (Co3O4, ZrO2) through a series of characterizations, in which graphite‐coated alloys and metal oxides are found to be the catalytically active species. The doping of the second metal results in a significant enhancement for the number of active sites in the catalyst, and the d‐band center is shifted toward a deviation from the Fermi energy level. Among the tested catalysts, Co‐Zr@Chitosan‐20 exhibits superior catalytic activity for the reductive amination of biobased levulinic acid to 5‐methyl‐2‐pyrrolidone in 99.3% selectivity and 92.8% yield. This non‐noble metal bimetallic synergistic catalytic protocol opens an avenue for efficiently producing biomass‐derived nitrogenous chemicals.

Highly Efficient and Recyclable Nitrogen-Doped Mesoporous Carbon-Supported Ru Catalyst for the Reductive Amination of Levulinic Acid/Esters to Pyrrolidones

“…N-doped mesoporous carbon (NMC) has attracted a lot of attention and is used as a catalyst carrier due to its adjustable pore size and functionalization, high surface area, good hydrothermal stability, and electron conduction. Moreover, the replacement of the C atom by a N atom can lower the valence band, increase the chemical stability of the material, and increase the electron density at the Fermi energy level. ,− According to our previous study, NMC-embedded Ru showed excellent catalytic performance for the hydrogenolysis of LA to GVL, where the weak basicity of the N dopant may promote the adsorption of acidic LA and consequently accelerate the following hydrogenolysis reaction. This inspired us to design and develop a novel NMC-supported Ru multifunctional catalyst for the reductive amination of LA/esters with amines.…”

“…Currently, pyrrolidones are industrially produced by the reaction of γ-butyrolactone with the corresponding amines or by the dehydrogenation–amination of butanediol with suitable amines under harsh reaction conditions (>200 °C) . In contrast to these industrial methods using fossil resources, reductive amination of the renewable, readily available, and biomass-derived platform molecule LA with amines offers a sustainable production route for N -substituted 5-methyl-2-pyrrolidones. ,, In general, there are two common reaction pathways (Scheme ). In one pathway (path 1), initially, the intermediate imine a was easily generated through the nucleophilic attack of the −NH 2 group to the CO group of LA/esters.…”

“…11 In contrast to these industrial methods using fossil resources, reductive amination of the renewable, readily available, and biomass-derived platform molecule LA with amines offers a sustainable production route for N-substituted 5-methyl-2pyrrolidones. 10,13,14 In general, there are two common reaction pathways (Scheme 1). In one pathway (path 1), initially, the intermediate imine a was easily generated through the nucleophilic attack of the −NH 2 group to the C�O group of LA/esters.…”

Polymers without Petrochemicals: Sustainable Routes to Conventional Monomers

“…An excellent heterogenous catalytic system was developed by Shimizu and co-workers, where they demonstrated the amination with a wide range of amines with generally high yields and no solvent . Another example used Zr-Co catalysts prepared using chitosan as a carbon and nitrogen source to generate 5-methyl-2-pyrrolidone with a 93% yield . Homogenous catalysts were first reported in 2011 with the use of a ruthenium catalyst and formic acid .…”

Sustainable Efficient Synthesis of Pyrrolidones from Levulinic Acid over Pd/C Catalyst

“…For example, 5‐methyl‐2‐pyrrolidone (MPD) can be obtained by reductive amination of LA/ester in H 2 and ammonia gas or NH 3 ⋅H 2 O [10] . However, an excessive hydrogen pressure (30‐50 bar) is required in this process [10a,11] . To avoid high H 2 pressure, one synthesis technique of MPD is by using HCOOH as H source.…”