Unmodified Maghemite from River Sand as a Selective Catalyst for Base-Free Transfer Hydrogenation of Furfural, Levulinic Acid, and o-Vanillin: A Pathway for Sustainable Biomass Conversions

Abstract

Iron is one of the cheapest and abundant metals on the earth’s crust. Both its oxides and metallic form are highly active as oxidation and reduction catalysts. Its oxide forms such as Fe2O3 and Fe3O4 are magnetically active at room temperature, making them easy for separation and reuse. Fe2O3 exists in 14 different phases; among them, α, β, and γ are well known. We have separated phase-pure γ-Fe2O3 from the river sand and confirmed it by X-ray diffraction and selected area electron diffraction analyses. Its morphology was understood by scanning electron microscopy and high-resolution transmission electron microscopy analyses. The unmodified γ-Fe2O3 obtained from the natural source was employed as a catalyst for the transfer hydrogenation of carbonyl and nitro compounds and biomass derivatives such as levulinic acid, furfural, and vanillin, without using a base. Further, to understand the advantage of γ-Fe2O3 recovered from the natural source, phase-pure α-, β-, and γ-Fe2O3 were synthesized and characterized and their catalytic activity was studied under identical conditions. To our delight, γ-Fe2O3 recovered from the natural source exhibited superior activity under base-free conditions.

A Numerical Simulation and Experimental Study of Fluidization Characteristics of a Bubbling Fluidized Bed in Biomass Gasification

“…The CO origi Compared to QS samples, the WH samples showed significantly higher syngas yield and carbon conversion efficiency. The main component of hematite was Fe 2 O 3 , which precipitated lattice oxygen during gasification to promote rapid gasification reactions [44][45][46]. Researchers had found that the Fe-O bonds in the Fe 2 O 3 became weaken and break, which precipitated the lattice oxygen in the biomass gasification process [47,48].…”

Catalytic Transfer Hydrogenation of Lignocellulosic Biomass Model Compounds Furfural and Vanillin with Ethanol by an Air‐stable Iron(II) Complex

“…Heterogeneous catalysts also dominate the reduction of vanillin to vanillyl alcohol which is performed under harsh conditions. [12] Hence, there is a genuine need for the development homogeneous catalyst that can selectively reduce the aldehyde functionalities in furfural and vanillin under mild conditions maintaining the green sustainable aspects. The reduction of carbonyl compounds is one of the frequently used fundamental transformations in chemical syntheses.…”

“…Few catalysts with base metals such as Fe, [9] Co [10] and Cu [11] were also used. Heterogeneous catalysts also dominate the reduction of vanillin to vanillyl alcohol which is performed under harsh conditions [12] . Hence, there is a genuine need for the development homogeneous catalyst that can selectively reduce the aldehyde functionalities in furfural and vanillin under mild conditions maintaining the green sustainable aspects.…”