Influence of Highly Stable Ni²⁺ Species in Ni Phyllosilicate Catalysts on Selective Hydrogenation of Furfural to Furfuryl Alcohol

Abstract

Enhancing the catalytic performance of non-noble Ni catalysts in the selective hydrogenation of furfural to furfuryl alcohol (FA) in terms of furfural conversion, selectivity, and good recyclability is challenging. Here, spherical nickel phyllosilicate catalysts (Ni_PS) with fibrous-like structures are prepared via a modified sol–gel method with Ni loadings of 2–30 wt %. Upon exposure to air, all the reduced Ni_PS catalysts exhibit more than 80% Ni0/Niphyllosilicate species on the surface, whereas a large portion of Ni oxide species (>55%) is presented on the impregnated catalyst. The Ni2+ species in nickel phyllosilicate catalysts are active and highly stable during reduction, reaction, and regeneration, yielding stable catalytic performance for multiple recycle tests in furfural hydrogenation to FA. Furfural conversion over the Ni_PS catalysts increased monotonically with increasing Ni loading without an FA selectivity drop. The presence of both metallic Ni0 and Niphyllosilicate also produces a synergistic promotional effect for FA formation.

Ru Supported on Ni Phyllosilicate-Modified MCF as a Novel Nanocatalyst for Selective Hydrogenation of Biobased Citronellal to Citronellol

“…These peaks can be ascribed to the existence of Ni-PS with formula Ni 3 Si 2 O 5 (OH) 4 , which indicates the Ni:Silicate in 1:1 form. 32,33 The binding energies for Si 2p, Si 2s, and O 1s elemental states show similar results as given in the literature for the MCF support. 46 3.4.…”

“…Ni 2p XPS spectrum produced strong peaks at around 856.74 and 874.19 eV, corresponding to the Ni 2p3/2 and Ni 2p1/2 orbitals along with their respective satellite peaks for Ni 2+ species. These peaks can be ascribed to the existence of Ni-PS with formula Ni 3 Si 2 O 5 (OH) 4 , which indicates the Ni:Silicate in 1:1 form. , The binding energies for Si 2p, Si 2s, and O 1s elemental states show similar results as given in the literature for the MCF support …”

“…The formation of Ni-phyllosilicate (Ni-PS) on MCF was obtained by addition of aqueous ammonia during metal loading, which further helped in the controlled hydrogenation of citronellal successfully. Earlier studies report Ni-PS formation on silica and SBA-15 support for different applications. − Whereas, we report the novel Ni-PS formation on the MCF support.…”

In Situ TEM Study of the Genesis of Supported Nickel Catalysts

“…The chosen temperature of 500 °C represents the center of the reduction peak for nickel phyllosilicates (Figure E) and is a temperature at which there is enough thermal energy delivered to the sample to render the energy contribution of the electron beam insignificant. Additionally, the use of lower reduction temperatures is often preferable in an industrial context for reasons of safety and cost, and has been known to increase the activity of such catalysts . The experiments presented show that reduction at 500 °C compared to 600 °C increases the time of particle nucleation and growth from 25 to 180 s. This increase in particle growth time is insignificant when considering that reduction of this material in the literature is usually performed for lengths of time consisting of hours rather than minutes .…”

“…Additionally, the use of lower reduction temperatures is often preferable in an industrial context for reasons of safety and cost, and has been known to increase the activity of such catalysts. 32 The experiments presented show that reduction at 500 °C compared to 600 °C increases the time of particle nucleation and growth from 25 to 180 s. This increase in particle growth time is insignificant when considering that reduction of this material in the literature is usually performed for lengths of time consisting of hours rather than minutes. 33 As such, we believe that this choice of temperature remains relevant and has the potential to guide others in the choices of temperatures and lengths of time needed to reduce such catalyst precursors.…”