Phase‐Dependent Stability and Substrate‐Induced Deactivation by Strong Metal‐Support Interaction of Ru/TiO₂ Catalysts for the Hydrogenation of Levulinic Acid

Abstract

The choice of support type has a profound influence on catalyst performance in liquid phase hydrogenation reactions, including the catalytic hydrogenation of biomass‐derived levulinic acid (LA) to γ‐valerolactone (GVL). Catalytic performance, including stability, of three Ru/TiO2 catalysts, having a similar mean Ru metal nanoparticle size but supported on three types of TiO2, namely P25, rutile and anatase, is evaluated by multiple reuse under batch reactor conditions. T3he catalysts’ physicochemical properties before and after recycling are characterized by XRD, STEM, TGA and FT‐IR after CO stepwise adsorption. The results show that the deactivation seen for (mixed) anatase‐supported catalysts in dioxane can be attributed to strong metal‐support interaction (SMSI) rather than coke formation or metal sintering, with the rutile‐based catalyst being more resistant against such support reduction. Notably, SMSI formation under the applied, relatively mild conditions only occurs in the presence of organic acids, such as LA or valeric acid.

TiO2 supported Ru catalysts for the hydrogenation of succinic acid: influence of the support

“…32 The group of Weckhuysen have further reported the absence of any sintering when Ru was supported on a mixed phase as well as on pure rutile supports, while Ru sintering was observed on pure anatase phase. 33 Further, Sassoye et al indicated that the migration of RuO2 can be observed from the anatase to the rutile phase when the TiO2 support contains both polymorphs. 34 This confirmed the existence of weaker interactions of the supported Ru species with the anatase phase than with the rutile phase.…”

“…34 The group of Weckhuysen also evidenced that the Ru catalyst stability depended on the crystallographic nature of the titania support, strong sintering being observed on pure anatase, while an irreversible reduction of the anatase support caused by strong levulinic acid adsorption induced the SMSI effect. 33…”

Unexpected reactivity related to support effects during xylose hydrogenation over ruthenium catalysts

“…For example, Zhang et al observed smaller ruthenium nanoparticles on TiO 2 anatase than on TiO 2 rutile, 24 whereas other authors observed smaller ruthenium nanoparticles and a more homogeneous repartition of nanoparticles on TiO 2 rutile. [27][28][29][30] In this paper, the impact of TiO 2 support on the reactivity of ruthenium catalysts in xylose hydrogenation was investigated with a focus on the differences in reactivity observed when different supports are used. Two catalysts with two different commercial TiO 2 , anatase and rutile, were prepared, characterized and tested for xylose hydrogenation.…”

Correlation between the TiO2 encapsulation layer on Pt and its electrochemical behavior

“…[6,7] Yet, impermeable and thick support layers over the catalysts can also lead to a decrease in performance by blocking active sites. [8,9] Therefore, probing the existence and specific role of the encapsulation layer of SMSI materials is crucial to understand their performance in catalytic reactions. Although the existence of thin encapsulation layers on metal catalysts was recently proved by electron microscopy, [10][11][12][13][14] structure-property relationships were rarely investigated, especially in the case of electrochemical properties.…”