Understanding the Role of Metal-Modified Mo(110) Bimetallic Surfaces for C–O/C═O and C–C Bond Scission in C3 Oxygenates

Abstract

Bond scission of C−O/CO, C−C, and C−H from oxygenates on Mo(110), Ni/Mo(110), and Co/ Mo(110) has been investigated via density functional theory (DFT) calculations, temperature-programmed desorption (TPD), and high-resolution electron energy loss spectroscopy (HREELS). Propanal and 1-propanol are used as probe molecules for biomass-derived oxygenates due to their relatively high vapor pressures, allowing their easy introduction into UHV systems. DFT results predict that the binding energy trend of propanal and 1-propanol is Mo(110) > Co/ Mo(110) > Ni/Mo(110), which suggests that binding energies are reduced by the modification of Mo(110) with Ni and Co admetals. TPD and HREELS results show that bond scission activity and selectivity can be tuned upon admetal modification of Mo(110). For both molecules, Mo(110) shows a highly selective deoxygenation pathway toward C−O/CO bond scission to produce propene, while bimetallic surfaces instead exhibit a higher activity for C−C and C−H bond scission. Among the three surfaces, Ni modification leads to the highest selectivity for decarbonylation to produce ethylene and Co modification results in the highest selectivity for reforming to produce syngas.

Trends in the Surface and Catalytic Chemistry of Transition-Metal Ceramics in the Deoxygenation of a Woody Biomass Pyrolysis Model Compound

“…In contrast, an appreciable body of literature concerning the catalytic deoxygenation over TM ceramics indicates that these materials have the potential to exhibit the special and appropriate level of oxophilicity, carbon affinity, and atomic H reactivity necessary to efficiently drive oxygen removal without hydrogenating valuable unsaturated products. ,,, For example, propanal deoxygenation to propylene over NiMo and CoMo alloys and Mo 2 C and WC ceramics showed a stark contrast in product distributions. , The metal alloys yielded CO and ethylene as major products, yet the TM ceramics produced propylene with moderate selectivity (selectivity 60%). This trend continues in the study of suites of transition-metal phosphides by Oyama and co-workers .…”

Conjugation-Driven “Reverse Mars–van Krevelen”-Type Radical Mechanism for Low-Temperature C–O Bond Activation

“…8,9 Experimental studies of ethanol conversion on group 8−11 transition metal catalysts of varying oxophilicity (Cu, Pt, Pd, Ir, Rh, Ru) confirm that reforming reactions are dominant and the yield to hydro-carbons (ethylene and ethane) is negligible. 10 Similarly, UHV experiments indicate that the rates of 1-propanol and ethylene glycol selective deoxygenation on oxophilic Mo(110) 11 and Mo 2 C 12 surfaces are lower than that of C−C bond scission over reforming catalysts Ni(111) and Fe/Ni(111). 13 Late transition metals are deemed ineffective for C−O scission due to poisoning by the CO byproduct and requirement of large metal clusters.…”

Selective hydrogenation of biomass-derived 2(5H)-furanone over Pt-Ni and Pt-Co bimetallic catalysts: From model surfaces to supported catalysts

“…Vorotnikov et al [24] preformed DFT calculations to investigate the reaction mechanisms and reaction barriers for the hydrogenation of furfural to 2-methyfuran, furfuryl alcohol and furan on Pd(111). Myint et al [25,26] compared the adsorption and reaction pathways of propanal and 1-propanol on Ni/Fe(111), Cu/Ni(111) and Ni/Mo(110) bimetallic surfaces using DFT calculations and temperature-programmed desorption (TPD). Similar theoretical and experimental studies have been carried out to study the hydrogenation of C=C bonds in a variety of molecules over the 3d/Pt(111) model surfaces and supported Pt-3d bimetallic catalysts [27][28][29].…”