Solvent Additive-Induced Deactivation of the Cu–ZnO(Al₂O₃)-Catalyzed γ-Butyrolactone Hydrogenolysis: A Rare Deactivation Process

Abstract

This work reports initial results on the effect of low concentrations (ppm level) of a stabilizing agent (2,6-di- tert -butyl-4-methylphenol, BHT) present in an off-the-shelf solvent on the catalyst performance for the hydrogenolysis of γ-butyrolactone over Cu–ZnO-based catalysts. Tetrahydrofuran (THF) was employed as an alternative solvent in the hydrogenolysis of γ-butyrolactone. It was found that the Cu–ZnO catalyst performance using a reference solvent (1,4-dioxane) was good, meaning that the equilibrium conversion was achieved in 240 min, while a zero conversion was found when employing tetrahydrofuran. The deactivation was studied in more detail, arriving at the preliminary conclusion that one phenomenon seems to play a role: the poisoning effect of a solvent additive present at the ppm level (BHT) that appears to inhibit the reaction completely over a Cu–ZnO catalyst. The BHT effect was also visible over a commercial Cu–ZnO–MgO–Al 2 O 3 catalyst but less severe than that over the Cu–ZnO catalyst. Hence, the commercial catalyst is more tolerant to the solvent additive, probably due to the higher surface area. The study illustrates the importance of solvent choice and purification for applications such as three-phase-catalyzed reactions to achieve optimal performance.

Copper-doped activated carbon from amorphous cellulose for hydrogen, methane and carbon dioxide storage

“…of 933.1 eV (marked in blue in Fig. 5B) is assigned to Cu 0 /Cu þ species, while the component at about 934.6 eV (red) corresponds to Cu 2þ species [87,88]. The additional peak at about a 936.1 eV (dark yellow) can be ascribed to copper hydroxide (Cu(OH) 2 ) [89,90].…”

Synergistic Catalysis for Promoting Ring-Opening Hydrogenation of Biomass-Derived Cyclic Oxygenates

“…In the Cu−ZnO catalyzed γ-butyrolactone hydrogenation system, the ppm level of a stabilizing agent (2,6-di-tert-butyl-4-methylphenol, BHT) in solvent THF could poison the interfacial Cu−ZnO sites, leading to the deactivation of Cu−ZnO-catalyzed γ-butyrolactone hydrogenation. 151 Although Cu-based catalysts showed high efficiency in the hydrogenation of γ-valerolactone or γ-butyrolactone, Huber et al found the reaction rate of γ-butyrolactone hydrogenation to 1,4-butanediol upon Co/TiO 2 -R is >8 times more active than Cu/TiO 2 -R. 152 Introducing 5−25 mol % of Cu to the Co/TiO 2 -R could further increase the production rate of 1,4-butanediol by 2.1−2.5 times. The formation of a CuCo alloy with a Co-rich core and Cu-rich shell is responsible for the high reaction rate and 1,4-butanediol selectivity.…”

“…In addition, the introduction of LaO x suppresses the oxidation of Cu during the reaction, ensuring the catalyst stability during multiple recycles. In the Cu–ZnO catalyzed γ-butyrolactone hydrogenation system, the ppm level of a stabilizing agent (2,6-di- tert -butyl-4-methylphenol, BHT) in solvent THF could poison the interfacial Cu–ZnO sites, leading to the deactivation of Cu–ZnO-catalyzed γ-butyrolactone hydrogenation …”