CO2 hydrogenation to methanol can play an important role in meeting the sustainability goals of the chemical industry. In this study, we investigated in detail the role of the Cu–CeO2 interactions for methanol synthesis, emphasizing the role of the copper surface and interface sites between copper and ceria for the hydrogenation of CO2 and CO. A combined CO2–N2O titration approach was developed to quantify the exposed metallic copper sites and ceria oxygen vacancies in reduced Cu/CeO2 catalysts. Extensive characterization shows that copper dispersion is strongly enhanced by strong Cu–CeO2 interactions in comparison to Cu/SiO2. CO2 hydrogenation activity data show that the Cu/CeO2 catalysts displayed higher methanol selectivity compared to a reference Cu/SiO2 catalyst. The improved methanol selectivity stems from inhibition of the reverse water-gas-shift activity. The role of CO in CO2-to-methanol conversion was studied by steady-state and transient cofeeding activity measurements together with (quasi) in situ characterization (TPH, XPS, SSITKA, and IR spectroscopy). The Cu–CeO2 interface provides active sites for the direct hydrogenation of CO to methanol via a formyl intermediate. Cofeeding of small amounts of CO2 to a CO/H2 mixture poisons these interfacial sites due to the formation of carbonate-like species. Methanol synthesis proceeds mainly via CO2 hydrogenation in which the metallic Cu surface provides the active sites.

New understanding on reaction mechanism of cellulose hydrogenolysis to ethylene glycol over WO3–ZrO2 catalyst combined with Ru/C.

An unprecedented 80.2% yield of alkyl levulinate was obtained via one-pot conversion of furfural with 2-propanol over Au-H4SiW12O40/ZrO2.

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Biomass-derived ethyl levulinate can flexibly convert to GVL, EHP, 1,4-PDO and 2-MTHF with excellent selectivity on a supported cobalt catalyst.

Glycols are accessible via metal-catalyzed hydrogenolysis of sugar alcohols such as xylitol obtained from hemicellulose. Rubased catalysts are highly active but also catalyze side-reactions such as decarbonylation and deoxygenation. To achieve high selectivity, these reactions need to be suppressed. In our study, we introduce heteroatom doped carbon materials as catalyst supports providing high selectivity. Heteroatom doping with nitrogen and oxygen was achieved by treating activated carbon with HNO 3 , NH 3 and H 2 or carbonization of organic precursors.For all N-doped materials a high glycol selectivity of �80 % for sorbitol and xylitol and 44 % for xylose and glucose was reached. XPS analysis confirms the presence of different nitrogen species at the carbon surface and varying ligand effects for oxygen and nitrogen. Oxygen has an electron withdrawing effect on ruthenium and leads to a decreased activity. Nitrogen has weaker electron withdrawing properties, resulting in an enhanced selectivity.

The kinetics of the transformation of metallic Fe to the active Fe carbide phase at the start of the Fischer–Tropsch (FT) reaction were studied. The diffusion rates of C atoms going in or out of the lattice were determined using 13C-labeled synthesis gas in combination with measurements of the transient 12C and 13C contents in the carbide by temperature-programmed hydrogenation. In the initial 20 min, C diffuses rapidly into the lattice occupying thermodynamically very stable interstitial sites. The FT reaction starts already during these early stages of carburization. When reaching steady state, the diffusion rates of C in and out of the lattice converge and the FT reaction continues via two parallel reaction mechanisms. It appears that the two outer layers of the Fe carbide are involved in hydrocarbon formation via a slow Mars–Van Krevelen-like reaction contributing to ∼10% of the total activity, while the remainder of the activity stems from a fast Langmuir–Hinshelwood reaction occurring over a minor part of the catalyst surface.