No abstract

We have investigated a series of supported and unsupported nickel and cobalt catalysts, principally using neutron vibrational spectroscopy (inelastic neutron scattering, INS). For an alumina supported Ni catalyst we are able to detect hydrogen on the metal for the first time, all previous work has used Raney Ni. For an unsupported Ni foam catalyst, which has similar behaviour to Raney Ni but with a much lower density, the spectra show that there are approximately equal numbers of (100) and (111) sites, in contrast to Raney Ni that shows largely (111) sites. The observation of hydrogen on cobalt catalysts proved to be extremely challenging. In order to generate a cobalt metal surface, reduction in hydrogen at 250–300 °C is required. Lower temperatures result in a largely hydroxylated surface. The spectra show that on Raney Co (and probably also on a Co foam catalyst), hydrogen occupies a threefold hollow site, similar to that found on Co($$10\bar{1}0$$ 10 1 ¯ 0 ). The reduced surface is highly reactive: transfers between cells in a high quality glovebox were sufficient to re-hydroxylate the surface.

No abstract

Cu‐Co‐based catalysts provide promising systems for higher alcohol synthesis (HAS) due to a synergistic dual‐site mechanism. Bimetallic Cu‐Co (alloy) nanoparticles are assumed to be the active sites, but cobalt carbide (Co2C) forming under reaction conditions also seems to influence the formation of C2+OH. Na‐doped Co‐modified Cu/ZnO/Al2O3 is applied as benchmark catalyst within the Carbon2Chem® subproject L4 providing suitable performance in terms of CO conversion and C2+OH selectivity. However, further optimization is required in order to develop an economically viable HAS process.

The deactivation of a heterogeneous Cu/Ni/Cr‐Al2O3 aldehyde hydrogenation catalyst was studied using n‐nonyl aldehyde as model reactant. The reaction network was experimentally determined in batch experiments at 180 °C and 25 bar with either fresh or spent catalyst and also w/o the presence of the catalyst. Accelerated aging was applied to stress the fresh catalyst under model reaction conditions for characterization and comparison to a spent catalyst from an industrial plant. The catalyst structure and morphology were studied by XRD and TEM/EDX. The carbon residues that strongly adsorb on the catalyst surface during hydrogenation were analyzed by BET, TGA, extraction, and chemical disintegration. The amount of strongly adsorbed heavy hydrocarbons was 10 w % for the spent catalyst, causing a decrease in pore volume by 30 %. Regeneration of the catalyst was successfully conducted via oxidation of the carbon residues.