Catalytic Pathways for Deoxygenation and Carbon-Carbon Formation on Supported Metal Clusters

MARÍA EUGENIA SAD; DE CHEN; ENRIQUE IGLESIA

San Francisco, CA , Estados Unidos

Congreso; 239th ACS National Meeting San Francisco, CA; 2010

ACS

Propanediol, propanol and propanal are used as reactants to probe oxygen removal pathways involving intramolecular decarbonylation, direct reactions with CO, and hydrodeoxygenation and hydrogenolysis using H2 formed in situ from CO-H2O mixtures on supported metal clusters.   Group VIII and Ib metals catalyze these reactions, as well as the aldol condensation and esterification of reactants and intermediates and form larger molecules (C4+ alkanes, alkenes, and oxygenates) with fewer O-atoms than oxygenate reactants.  Specifically, these C3 oxygenates form C-C bonds on metal clusters and 3-pentanone as the initial product via aldol-type condensation steps that remove O-atoms as CO and preserve valuable H-atoms within reaction products.  CO reacts directly with alkanols via steps analogous to those involved in water-gas shift to form alkanes at rates much higher that for alkanol hydrogenolysis with H2 as co-reactant.  These C-C and C-O activation reactions occur predominantly via monofunctional pathways on metal surfaces; rates and selectivities are influenced by the size of metal clusters but not by the identity of the support.