Chlorine Influence on Palladium Doped Nickel Catalysts in Levulinic Acid Hydrogenation with Formic Acid as Hydrogen Source

Abstract

Levulinic acid (LA) is a platform molecule, and its valorization toward biofuel additives like γ-valerolactone or tetrahydrofuran is considered as an important step in planning future biorefinery schemes. In this study, various Ni based catalysts were studied for the LA hydrogenation with formic acid (FA) used as a hydrogen source. Two different ways of catalytic activity improvement are discussed (nickel loading vs addition of dopants). The influence of Ni doping by small amount of noble metals (Pt, Pd, Ru, Rh) showed that Ni−Pd is the most active catalyst. Its high catalytic performance is attributed to the synergic effect between two metals and interaction with chlorine. The effect of chlorine on catalytic performance and properties of the catalysts was evaluated by variety of surface and bulk-sensitive characterization methods. It was shown that addition of chlorine is one of the key factors required for high catalytic performance. Chlorine influences distribution of metals on the surface of the catalyst, their interaction with support and facilitates the formation of small crystallites, which is beneficial for reaching high catalytic activity.

Ni-Pd/γ-Al2O3 Catalysts in the Hydrogenation of Levulinic Acid and Hydroxymethylfurfural towards Value Added Chemicals

“…Furthermore, the presence of chlorine derived from the palladium precursor may facilitate the reduction of NiO x and inhibit the formation of the interfacial NiAl x O y spinel [18]. For the 4%Ni-1%Pd catalyst, a high-temperature effect was observed in the temperature range 220-350 • C associated with the reduction of NiO x species [20,21,32], so that modifying the Ni catalyst with Pd as dopant facilitated the reduction of nickel.…”

“…Monometallic Ni catalyst can be, however, modified by the addition of a second metal, that can result in the formation of new active sites and can increase the catalyst stability due to the establishment of intermetallic interactions and the modification of Ni interaction with the support. In particular, Ni-Pd catalysts showed higher activity and selectivity as compared to their single counterparts in the hydrogenation of both HMF [17] and LA substrates [18]. Mihet et al [19,20] showed that the introduction of small amounts (0.5%) of Pd and Rh noble metals to the 10% Ni/Al 2 O 3 catalyst reduces the crystallite size, with higher activity following in both NO reduction and CO 2 methanation.…”

“…Total hydrogenation of unsaturated compounds like HMF and furfural was achieved over the bimetallic Ni-Pd/SiO 2 catalyst, and the key role played by the alloy was hypothesized. When it comes to LA hydrogenation with FA as a hydrogen source reaction, we demonstrated recently that among the noble metal dopants (Pt, Pd, Ru, Rh) of Ni catalyst, Pd was the most active, and preliminary results showed that the activity of the bimetallic Ni−Pd catalysts could be tuned depending on the preparation method [18].…”

Catalyst Stability—Bottleneck of Efficient Catalytic Pyrolysis

“…On the other hand, its positive effect is recognized. Chlorine presence during the catalyst's synthesis can enhance the reducibility of Ni and improve its dispersion in the final catalyst [82]. On the other hand, the presence of chlorine in the reaction feed during the upgrade of pyrolysis products enhanced the sintering of nickel nanoparticles on the catalyst, which, in consequence, contributed to the activity decrease [62].…”

Solvothermal hydrodeoxygenation of hydroxymethylfurfural derived from biomass towards added value chemicals on Ni/TiO2 catalysts

“…Lignocellulosic biomass is one of the most abundant renewable source of commodity chemicals [1,2] 5-(hydroxymethyl)furfural (HMF) that can be obtained via cellulose hydrolysis has been identified as valuable fuel, polymer, or chemical precursor. [3][4][5] Depending on the catalysts and reaction conditions HMF can be transformed towards a large variety of chemicals including 2,5-dimethylfuran (DMF), 5-methylfurfural (5-MF) or 2,5-bishydroxymethyltetrahydrofuran (BHMTHF) through hydrodeoxygenation (HDO) reaction (scheme 1).…”