Enhanced Catalytic Transfer Hydrogenation of Ethyl Levulinate to γ-Valerolactone over a Robust Cu–Ni Bimetallic Catalyst

Abstract

An efficient and robust bimetallic catalyst has been developed for the transfer hydrogenation of biomass derived ethyl levulinate to γ-valerolactone with 2-butanol as the hydrogen donor. Several bimetallic catalysts were prepared and characterized by Brunauer−Emmett−Teller, transmission electron microscopy, X-ray power diffraction and X-ray photoelectron spectrometry. They exhibited different catalytic activities in the catalytic transfer hydrogenation (CTH) reaction. Results showed that 10Cu-5Ni/Al 2 O 3 had the highest activity, providing a 97% yield of GVL product in 12 h at 150 °C. The reaction temperature, reaction time and catalyst loading were also investigated and found to affect the product yield. The catalyst was also successfully applied to the CTH of various levulinate esters with different secondary alcohols. Comparing experiments between Cu−Ni and Cu catalysts and the poisoning experiments revealed that the introduction of Ni to Cu remarkably enhanced the catalyst's activity and stability, showing an outstanding recycling ability in the 10 runs recycling experiments without notable loss in the activity.

xNi–yCu–ZrO2 catalysts for the hydrogenation of levulinic acid to gamma valorlactone

“…In general hydrogenation catalysis studies have either relied on the traditional precious metals or applied the same impregnation/deposition methods used to form metal nanoparticles for those catalysts to the synthesis of materials with copper as the active component. For example, Cu-Ni/Al 2 O 3 , with Ni the minor component, prepared by incipient impregnation has been reported [18] and showed 50% GVL yield after 2 h of reaction at 150 °C for the catalytic transfer hydrogenation of ethyl levulinate.…”

Design of Efficient Noble Metal Free Copper‐Promoted Nickel‐Ceria‐Zirconia Nanocatalyst for Bio‐Fuel Upgrading

“…In the control experiment, single metal catalysts of Ni and Cu could be recycled only for two times, because of accumulation of carbonaceous species on the catalyst surface which blocked active sites and detached metals from the supports. On the contrary, the bimetallic catalyst attained modulated electron properties by alloying ,. When Cu−Ni/CeO 2 and Cu−Ni/ZrO 2 catalysts was tested up to 6 th runs (Figure c), the conversion and 2‐methoxy‐4‐methylphenol selectivity were dropped from 78.3 to 60.5% and from 85.6 to 75.3% after 6 th runs, respectively.…”

Efficient Ni‐Cu/AC Bimetal Catalyst for Hydrogenolysis of Lignin to Produce High‐Value‐Added Chemicals

“…However, the results of the catalyst with different Ni/Cu ratio shows that both the yield of bio‐oil and the conversion of lignin decreased with the increase of Cu content in the Ni−Cu/AC. Many studies on bimetallic catalyst have found that the synergistic effect of the two metals would increase the active site on metal catalyst, reduce the size of the metal particle, and improve the dispersion of the metal, which in turn increase the catalytic activity of the bimetallic catalyst . It has also been reported that the presence of Cu could lower the reduction temperature of Ni species and provided more reduced Ni sites for the hydrogenation reaction.…”

“…Toledano et al used Ni/Al‐SBA‐15 catalyst to depolymerize lignin, and 30% yield of bio‐oil with the products distribution of phenols, aromatic aldehydes, ketones and esters was achieved. According to our previous reports, the Ni−Cu bimetallic catalyst has high catalytic activity in the synthesis of ethyl levulinate to γ‐amyl ester. The metal Cu in catalyst is easy to lose the peripheral electrons during the hydrogenation reaction, resulting in a decrease in catalytic activity.…”