Ni Supported on Natural Clays as a Catalyst for the Transformation of Levulinic Acid into γ-Valerolactone without the Addition of Molecular Hydrogen

Abstract

<jats:p>γ-Valerolactone (GVL) is a valuable chemical that can be used as a clean additive for automotive fuels. This compound can be produced from biomass-derived compounds. Levulinic acid (LA) is a compound that can be obtained easily from biomass and it can be transformed into GVL by dehydration and hydrogenation using metallic catalysts. In this work, catalysts of Ni (a non-noble metal) supported on a series of natural and low-cost clay-materials have been tested in the transformation of LA into GVL. Catalysts were prepared by a modified wet impregnation method using oxalic acid trying to facilitate a suitable metal dispersion. The supports employed are attapulgite and two sepiolites with different surface areas. Reaction tests have been undertaken using an aqueous medium at moderate reaction temperatures of 120 and 180 °C. Three types of experiments were undertaken: (i) without H2 source, (ii) using formic acid (FA) as hydrogen source and (iii) using Zn in order to transform water in hydrogen through the reaction Zn + H2O → ZnO + H2. The best results have been obtained combining Zn (which plays a double role as a reactant for hydrogen formation and as a catalyst) and Ni/attapulgite. Yields to GVL higher than 98% have been obtained at 180 °C in the best cases. The best catalytic performance has been related to the presence of tiny Ni particles as nickel crystallites larger than 4 nm were not present in the most efficient catalysts.</jats:p>

Zr supported on non-acidic sepiolite for the efficient one-pot transformation of furfural into γ-valerolactone

“…After calcination, sepiolite suffers a modification in its structure due to the loss of water. A phase change occurs due to the loss of the bound of H 2 O, which produces a rotation of the phyllosilicate ribbons [52]. This leads to a change in the XRD pattern of sepiolite (Fig.…”

Electrodeposited Ni-Rich Ni–Pt Mesoporous Nanowires for Selective and Efficient Formic Acid-Assisted Hydrogenation of Levulinic Acid to γ-Valerolactone

“…The high energy consumption required to vaporize LA makes this approach less attractive compared to the liquid-phase hydrogenation. Typically, the conversion of LA to GVL can be performed using three different hydrogen sources: (i) molecular hydrogen from an external source, (ii) hydrogen generated in situ from the decomposition of formic acid (FA), or (iii) by the Meerwein–Ponndorf–Verley reaction using alcohols. − Further, to exploit the facile separation of the liquid products upon hydrogenation, the conversion of LA to GVL has been extensively studied using molecular hydrogen under heterogeneous catalysis. − …”

Clays and the Origin of Life: The Experiments

“…Clay minerals can be employed as solid acids for several reactions typically catalyzed by mineral acids in aqueous solutions, e.g., the esterification of carboxylic acids [176][177][178][179][180][181] (Scheme 3), lactone production [182][183][184], and the formation of amines, amides, enamines, and amino acids [185][186][187][188][189][190] (Scheme 4). Clay minerals can be employed as solid acids for several reactions typically catalyzed by mineral acids in aqueous solutions, e.g., the esterification of carboxylic acids [177][178][179][180][181][182] (Scheme 3), lactone production [183][184][185], and the formation of amines, amides, enamines, and amino acids [186][187][188][189][190][191] (Scheme 4). Adsorption on the different surfaces of a clay mineral lowers the dimensionality of the reaction space from 3 to 2.…”

“…Several Diels-Alder cycloadditions are catalyzed by Lewis acids and are sensitive to clay mineral catalysts [168,174,192,193] (Scheme 5). Clay minerals can be employed as solid acids for several reactions typically catal by mineral acids in aqueous solutions, e.g., the esterification of carboxylic acids [177-(Scheme 3), lactone production [183][184][185], and the formation of amines, amides, enam and amino acids [186][187][188][189][190][191] (Scheme 4). Scheme 3.…”