Rational design for the fabrication of bulk Ni3Sn2 alloy catalysts for the synthesis of 1,4-pentanediol from biomass-derived furfural without acidic co-catalysts

This study describes the rational design for the fabrication of bulk Ni₃Sn₂ alloy catalysts for the de/hydration-hydrogenation of biomass-derived furfural (FFald) to 1,4-pentanediol (1,4-PeD) without the acidic co-catalyst. The presence of both hydration active sites (Brønsted acid sites (Ni-SnO_x)) and hydrogenation active sites (Ni⁰ or Ni-Sn alloy) in Ni₃Sn₂ alloy could be controlled by changing the pH of Ni-Sn solution during the preparation. Both active sites acted synergistically to catalyse the de/hydration-hydrogenation reactions of FFald to produce a high yield of 1,4-PeD in a batch reaction system at 433 K, 3.0 MPa H₂ after 12 h. Bulk Ni₃Sn₂ obtained at pH of Ni-Sn solution of 8-10, hydrothermal temperature of 423 K for 24 h, and reduction with H₂ at 673 K for 1.5 h demonstrated a high yield of 1,4-PeD (81-87%), which is comparable with that from previous work. A 76% yield of 1,4-PeD was also obtained when the reaction was carried out in a fixed-bed reaction system at 433 K, flow rate 0.065 mL min^-1, H₂ flow rate 70 mL min^-1, and 3.29 wt% FFald in H₂O/ethanol solution for 12 h. The activity of bulk Ni₃Sn₂ was maintained with 66% yield of 1,4-PeD even after 52 h reaction on stream. The fabricated bulk Ni₃Sn₂ alloy catalysts could be the promising heterogeneous Ni-Sn alloy-based catalysts for the catalytic conversion of biomass-derived-furanic compounds (e.g., FFald, furfuryl alcohol (FFalc), and 2-methylfuran (2-MeF)).

Effect of Precursor and Temperature Annealing on the Catalytic Activity of Intermetallic Ni3Sn2 Alloy

The effect of nickel precursors and the temperature annealing to obtain intermetallic Ni3Sn2 alloy catalysts on its activity and selectivity in the selective hydrogenation of biomass-derived furfural (FFald) were investigated. Two types of nickel precursors (c.a., i) nickel metal (Ni°) derived from Raney®nickel and ii) nickel ion (Ni2+) derived from nickel chloride) were employed as the starting materials via hydrothermal at 423 K for 24 h followed by reduction with H2 at the elevated temperature of 573-873 K for 1.5 h. The physico-chemical properties of the intermetallic Ni3Sn2 were characterized by XRD, N2-, and H2-adsorption, ICP-AES, and NH3-TPD. The intermetallic Ni3Sn2 alloy catalysts, both bulk and supported, demonstrated high activity and selectivity towards hydrogenation of FFald. The activity and selectivity of g-Al2O3 and AA-supported Ni3Sn2 alloy catalysts in the hydrogenation of FFald to furfuryl alcohol (FFalc) were maintained even after annealing at up to 873 K, but that of bulk Ni3Sn2 drastically dropped. Ni-Sn alloy catalysts which were obtained from Raney®Ni precursor showed more stable than that of nickel salts during hydrogenation of furfural to furfuryl alcohol. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Sustainable Routes for the Synthesis of Renewable Adipic Acid from Biomass Derivatives

Adipic acid (AA) is a key industrial dicarboxylic acid intermediate used in nylon manufacturing. Unfortunately, the traditional process technology is accompanied by serious environmental pollution. Given the growing demand for adipic acid and the desire to reduce its negative impact on the environment, considerable efforts have been devoted to developing more green and friendly routes. This Review is focused on the latest advances in the sustainable preparation of AA from biomass-based platform molecules, including 5-hydroxymethylfufural, glucose, γ-valerolactone, and phenolic compounds, through biocatalysis, chemocatalysis, and the combination of both. Additionally, the development of state-of-the-art catalysts for different catalytic systems systematically is discussed and summarized, as well as their reaction mechanisms. Finally, the prospects for all preparation routes are critically evaluated and key technical challenges in the development of green and sustainable processes for the manufacture of AA are highlighted. It is hoped that the green adipic acid synthesis pathways presented can provide insights and guidance for further research into other industrial processes for the production of nylon precursors in the future.

Unravelling the one-pot conversion of biomass-derived furfural and levulinic acid to 1,4-pentanediol catalysed by supported RANEY® Ni-Sn alloy catalysts

Bimetallic Ni–Sn alloys have been recognised as promising catalysts for the transformation of furanic compounds and their derivatives into valuable chemicals. Herein, we report the utilisation of a supported bimetallic RANEY® nickel–tin alloy supported on aluminium hydroxide (RNi–Sn(x)/AlOH; x is Ni/Sn molar ratio) catalysts for the one-pot conversion of biomass-derived furfural and levulinic acid to 1,4-pentanediol (1,4-PeD). The as prepared RNi–Sn(1.4)/AlOH catalyst exhibited the highest yield of 1,4-PeD (78%). The reduction of RNi–Sn(x)/AlOH with H₂ at 673–873 K for 1.5 h resulted in the formation of Ni–Sn alloy phases (e.g., Ni₃Sn and Ni₃Sn₂) and caused the transformation of aluminium hydroxide (AlOH) to amorphous alumina (AA). The RNi–Sn(1.4)/AA 673 K/H₂ catalyst contained a Ni₃Sn₂ alloy as the major phase, which exhibited the best yield of 1,4-PeD from furfural (87%) at 433 K, H₂ 3.0 MPa for 12 h and from levulinic acid (up to 90%) at 503 K, H₂ 4.0 MPa, for 12 h. Supported RANEY® Ni–Sn(1.5)/AC and three types of supported Ni–Sn(1.5) alloy (e.g., Ni–Sn(1.5)/AC, Ni–Sn(1.5)/c-AlOH, and Ni–Sn(1.5)/γ-Al₂O₃) catalysts afforded high yields of 1,4-PeD (65–87%) both from furfural and levulinic acid under the optimised reaction conditions.

The RANEY® Ni–Sn(x) alloy catalysed the one-pot conversion of biomass-derived furfural and levulinic acid to allow remarkable yield of 1,4-pentanediol (up to 90%) under the mild reaction conditions.