The hydrogenolysis and the aqueous phase reforming of glycerol have been investigated under mild reaction conditions, using water as the reaction medium and Pd/Fe as the catalyst. The experiments, in the presence of added H 2 or under inert atmosphere, clearly show that the dehydration/hydrogenation route is the key step in the case of C-O bond cleavage (hydrogenolysis) while dehydrogenation is a prerequisite for C-C bond breaking (APR), with the latter favoured at higher reaction temperatures. The temperature dependence of the C-C and C-O bond rupture is discussed by taking into account the bond energies involved in the competitive hydrogenolysis and APR reactions. Finally, the Pd/Fe catalyst was also tested in the hydrogenolysis and APR of ethylene glycol in the same temperature range, with the aim of clarifying the selective cleavage of C-O and C-C bonds in biomass derived C 2 -C 3 polyols.Catal. Sci. Technol. This journal is

The ready availability of esters from natural sources makes them promising substrates for the sustainable production of key intermediates of the chemical industry. In this context, methods to selectively cleave the alkoxy or ester C−O bond to obtain either alkane+acid or alcohol+aldehyde were investigated. Using Pd/Fe3O4(r) [(r)=reduced] as the catalyst of choice and either 2‐propanol—as indirect H source—or molecular hydrogen—as ample H source—the hydrogen coverage on the surface of the catalyst was controlled. This enabled selective cleavage of either the alkoxy C−O bond or the ester C−O bond in aromatic esters as shown for the hydrogenolysis of 2‐phenylethylacetate as model substrate. Noteworthy, hydrogenation of the aromatic ring was not observed. Thus, an exceptionally high chemoselectivity of Pd/Fe3O4(r) to hydrogenolysis of the ester group is combined with the option to readily direct the regioselectivity.

This paper describes a two-step process for hydrogen generation consisting of low-temperature (573 K) dehydrogenation of ethanol over copper chromite, followed by steam reforming (SR) over Ni/MgO at higher temperature (923 K). Advantages compared to direct SR of ethanol comprise suppression of coke formation. Water also moderates the rate of reduction of copper and promotes the stability of copper chromite at temperatures below 673 K. The two-step process requires a quantity of catalyst for the low-temperature step in excess of that for the high-temperature SR catalyst in order to ensure adequate conversion levels of ethanol in the first step.

The Cover shows how the selective hydrogenolysis of the alkoxy or ester C−O bond in 2‐phenylethylacetate to obtain either ethylbenzene+acetic acid or 2‐phenylethanol+ethanol was investigated. In their Full Paper, D. Cozzula et al. demonstrate how the alkoxy C−O bond was cleaved preferentially in the presence of 2‐propanol an as indirect H‐source, whereas cleavage of the ester C−O bond was favored in the presence of molecular hydrogen. In contrast, hydrogenation of the aromatic ring was not observed independent of the choice of the H‐source or the reaction conditions adopted. More information can be found in the Full Paper by D. Cozzula et al. on page 1515 in Issue 8, 2016 (DOI: 10.1002/cctc.201501414).