Selective aqueous phase hydrogenation of xylose to xylitol over SiO2-supported Ni and Ni-Fe catalysts: Benefits of promotion by Fe

Abstract

A monometallic Ni and a bimetallic Ni-Fe catalyst were used in the aqueous phase hydrogenation of xylose in batch conditions (T = 50 -150 °C, PH2 = 10 -30 bar, xylose mass fraction in water = 3.7 -11.0 wt.%) to evidence the benefits of promoting Ni by Fe. The activity of the catalysts increased with temperature, but a temperature of 80 °C allowed minimizing nickel leaching at full conversion. The presence of reduced Fe at the surface of the bimetallic nanoparticles increased both the first-order apparent rate constant and the adsorption constant of xylose. The catalytic activity of Ni/SiO2 strongly declined and no deactivation was found for the Ni-Fe catalyst. A restructuring of the bimetallic nanoparticles took place, as the size of the metal particles and the Fe proportion in the surface layers increased, suggesting a flattening and coalescing of the particles over the silica surface.

Ni-Fe alloying enhances the efficiency of the maltose hydrogenation process: The role of surface species and kinetic study

“…[28] In a few works, the advantages of adding iron to Ni for the aqueous phase hydrogenation of monosaccharides (xylose and glucose) have been reported and it was demonstrated that both the activity and stability of the catalysts were enhanced by Fe addition. [29][30][31] The objective of the present paper is to determine for the first time, through a kinetic study, to what extent a Ni-Fe/SiO 2 bimetallic catalyst would outperform a Ni/SiO 2 catalyst in the aqueous phase hydrogenation of maltose, as they have been reported to do for monosaccharides. [29][30][31] The effect of reaction parameters (e.g., temperature, maltose concentration, hydrogen pressure) on catalytic activity, selectivity, and stability will be examined.…”

Strengthening the Connection between Science, Society and Environment to Develop Future French and European Bioeconomies: Cutting-Edge Research of VAALBIO Team at UCCS

“…The Ni-Fe alloy is a good option to replace nickel catalysts. A Ni 62 Fe 38 /SiO 2 bimetallic catalyst prepared by deposition-precipitation with urea (DPU) showed high activity in the hydrogenation of xylose and maltose in water [49,50]. We showed that the temperatures of 50-80 • C are most favored due to the limitation of the metal leaching and the presence of a kinetic regime even for high masses of the catalyst.…”

“…The hydrogenation of the carbonyl groups of carbohydrates leads to the formation of polyols. Industrially, the three most important polyols are: sorbitol (from glucose) [47,48], xylitol (from xylose) [49] and maltitol (from maltose) [50]. In the case of xylitol, for example, the global industrial production is estimated to be about around 200 kt/year.…”

“…The selectivity to xylitol and maltitol (in the case of maltose hydrogenation) remained optimal and constant (~100%), even after three consecutive runs. The stability of the bimetallic catalysts was also better as compared to the Ni 100 /SiO 2 catalyst (Figure 7), which showed a decrease in the catalytic activity after the first catalytic test, which is associated with a more pronounced formation of the initial Ni 2+ -phyllosilicate phase [49]. In the case of the glucose hydrogenation, we applied the high-throughput (HT) methodology for each step of the process: synthesis, characterization and catalytic testing.…”

Exploring the Zn-regulated function in Co–Zn catalysts for efficient hydrogenation of ethyl levulinate to γ-valerolactone

“…It can change the electronic structure of the active metal, as well as its spatial structure and surrounding catalytic environment. [18][19][20] The doping of low boiling point Zn can not only improve the dispersibility and porosity of the metal catalyst through the volatilization of Zn at high temperature, but also improve the electronic environment and acidic sites of the metal active center, thereby improving the activity and stability of the catalyst. 21 The pore structure of the support and uniformity of the doping metal are important factors that affect the catalytic performance.…”