title: Kinetic modeling of Pt-catalyzed glycolaldehyde decomposition to syngas.
abstract: Fundamental knowledge of the elementary reaction mechanisms involved in oxygenate decomposition on transition metal catalysts can facilitate the optimization of future catalyst and reactor systems for biomass upgrade to fuels and chemicals. Pt-catalyzed decomposition of glycolaldehyde, as the smallest oxygenate with alcohol and aldehyde functionality, was studied via a DFT-based microkinetic model. It was found that two decomposition pathways exist. Under conditions of low hydrogen surface coverage, the initial C-H bond breaking reaction to HOCH(2)CO* is prevalent, while under conditions of high hydrogen coverage, the rather unexpected O-H bond forming reaction to HOCH(2)CHOH* is more active (subsequent decomposition is energetically favorable from HOCH(2)CHOH*). Our results indicate the possibility that (de)hydrogenation chemistry is rate-controlling in many small polyoxygenate biomass derivatives, and suitable catalysts are needed. Finally, DFT was used to understand the increased decomposition activity observed on the surface segregated Ni-Pt-Pt bimetallic catalyst. It was found that the initial O-H bond breaking of glycolaldehyde to OCH(2)CHO* has an activation barrier of just 0.21 eV. This barrier is lower than that of any glycolaldehyde consuming reaction on Pt. These computational predictions are in qualitative agreement with experimental results.
authors.affiliation: Department of Chemical Engineering, Catalysis Center for Energy Innovation and Center for Catalytic Science and Technology, University of Delaware, Newark, Delaware 19716-3110, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Salciccioli
authors.forename: Dionisios G
authors.initials: DG
authors.lastname: Vlachos
mesh_terms: D000079:Acetaldehyde / Q000031:analogs & derivatives* / Q000737:chemistry; D018533:Biomass; D002248:Carbon Monoxide / Q000737:chemistry*; D002384:Catalysis; D006859:Hydrogen / Q000737:chemistry*; D006865:Hydrogenation; D007700:Kinetics; D008956:Models, Chemical; D009532:Nickel / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D010313:Partial Pressure; D010984:Platinum / Q000737:chemistry*; D011789:Quantum Theory; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D010984:Platinum; D009532:Nickel; D002248:Carbon Monoxide; D006859:Hydrogen; D000079:Acetaldehyde; D010100:Oxygen; C010972:glycolaldehyde