Unraveling Unique Surface Chemistry of Transition Metal Nitrides in Controlling Selective C–O Bond Scission Pathways of Glycerol

Abstract

Controlled C–O bond scission is an important step for upgrading glycerol, a major byproduct from the continuously increasing biodiesel production. Transition metal nitride catalysts have been identified as promising hydrodeoxygenation (HDO) catalysts, but fundamental understanding regarding the active sites of the catalysts and reaction mechanism remains unclear. This work demonstrates a fundamental surface science study of Mo 2 N and Cu/Mo 2 N for the selective HDO reaction of glycerol, using a combination of model surface experiments and first-principles calculations. Temperature-programmed desorption (TPD) experiments showed that clean Mo 2 N cleaved two or three C–O bonds of glycerol to produce allyl alcohol, propanal, and propylene. The addition of Cu to Mo 2 N changed the reaction pathway to one C–O bond scission to produce acetol. High-resolution electron energy loss spectroscopy (HREELS) results identified the surface intermediates, showing a facile C–H bond activation on Mo 2 N. Density functional theory (DFT) calculations revealed that the surface N on Mo 2 N interacted with the H atoms in glycerol and blocked some Mo sites to enable selective C–O bond scission. This work shows that Mo 2 N and Cu/Mo 2 N are active and selective for the controlled C–O bond scission of glycerol and in turn provides insights into the rational catalyst design for selective oxygen removal of relevant biomass-derived oxygenates.

Pt- and Pd-modified transition metal nitride catalysts for the hydrogen evolution reaction

“…TMCs and TMNs typically exist in two common crystal phases: a face centered cubic rocksalt and a hexagonal close pack (HCP). 72,[76][77][78][79][80][81] In particular, many of these TMNs (e. g. NbN, VN, ZrN, RuN, TiN, CrN, and CoN) in rocksalt structures have been synthesized in previous experimental studies. [82][83][84][85][86][87] Therefore, we focus on the HER activity of 3d-5d TMNs in the rocksalt phase.…”

Electrochemical Surface-Enhanced Raman Spectroscopy (EC-SERS) Study of C3 Polyalcohols Oxidation Catalyzed by a Ag Roughened Electrode with Low Platinum Content

“…In the case of 1,3-PPD, steric hindrance causes the molecule to adsorb on the electrode surface through the end carbons, , leading to the fast formation of C1 species via C–C bond cleavage and Pt–CO formation. Our data shows that the presence of large quantities of Ag atoms and low Pt coverage prevents C1 product formation on alcohols with vicinal OH during the positive scan, with Ag and Pt mainly producing C3 and C2 species.…”

Kinetic Study of Liquid-Phase Glycerol Hydrodeoxygenation into 1,2-Propanediol over CuPd/TiO2-Na

“…In this way, Cu-based catalysts have been found to achieve high selectivity, but they are generally unstable. 3 , 7 − 11 On the other side, catalysts with Pt-, Ru-, Au-, Ni-, or Rh-containing materials are also active catalysts for this process, but their selectivity toward 1,2-PDO is not good enough. 10 , 12 , 13 …”

“…The current industrial synthesis of 1,2-PDO involves hydrolysis of propylene oxide with water at temperatures between 125 and 200 °C and 2 MPa pressure. , In the last few years, there have been many efforts aimed at the conversion of glycerol into 1,2-PDO by catalytic hydrodeoxygenation (HDO). In this way, Cu-based catalysts have been found to achieve high selectivity, but they are generally unstable. ,− On the other side, catalysts with Pt-, Ru-, Au-, Ni-, or Rh-containing materials are also active catalysts for this process, but their selectivity toward 1,2-PDO is not good enough. ,, …”