Herein, the development of an improved Pd on carbon nitride catalyst for direct H2O2 synthesis from the elements is reported. Microcalorimetric CO chemisorption is used to characterize the chemical speciation of the Pd-selective and -unselective sites. Selectivity trends among the samples suggest that a bare metal surface with a differential heat of CO chemisorption ranging between 140 and 120 kJ mol-1 is responsible for the total O2 hydrogenation, while a maximum threshold value of differential heat of CO chemisorption of approximately 70 kJ mol-1 is necessary for the partial hydrogenation of O2 to H2O2. Such a low differential heat of CO chemisorption indicates a low exposed metallic Pd surface subjected to electron withdrawal from the surrounding ligands: i.e., the N functional groups on the carbon support. With respect to N-containing carbon nanotubes, carbon nitrides provide the following: a higher concentration of N sites, a flexible network of π-conjugated polymeric subunits with sp3 linking subunits, and a flakelike morphology with high exposure of reactive C edge terminations. This results in a more effective kinetic stabilization of the electronically modified Pd species.

Pd Supported on Carbon Nitride Boosts the Direct Hydrogen Peroxide Synthesis

Salvatore, Abate;Gianfranco, Giorgianni;Gabriele, Centi;Siglinda, Perathoner;
2016-01-01

Abstract

Herein, the development of an improved Pd on carbon nitride catalyst for direct H2O2 synthesis from the elements is reported. Microcalorimetric CO chemisorption is used to characterize the chemical speciation of the Pd-selective and -unselective sites. Selectivity trends among the samples suggest that a bare metal surface with a differential heat of CO chemisorption ranging between 140 and 120 kJ mol-1 is responsible for the total O2 hydrogenation, while a maximum threshold value of differential heat of CO chemisorption of approximately 70 kJ mol-1 is necessary for the partial hydrogenation of O2 to H2O2. Such a low differential heat of CO chemisorption indicates a low exposed metallic Pd surface subjected to electron withdrawal from the surrounding ligands: i.e., the N functional groups on the carbon support. With respect to N-containing carbon nanotubes, carbon nitrides provide the following: a higher concentration of N sites, a flexible network of π-conjugated polymeric subunits with sp3 linking subunits, and a flakelike morphology with high exposure of reactive C edge terminations. This results in a more effective kinetic stabilization of the electronically modified Pd species.
2016
File in questo prodotto:
File Dimensione Formato  
acscatal.6b01889.pdf

solo utenti autorizzati

Descrizione: Articolo principale
Tipologia: Versione Editoriale (PDF)
Licenza: Tutti i diritti riservati (All rights reserved)
Dimensione 2.91 MB
Formato Adobe PDF
2.91 MB Adobe PDF   Visualizza/Apri   Richiedi una copia
Pd Supported on Carbon Nitride Boosts ... (Supporting information).pdf

solo utenti autorizzati

Descrizione: Supporting information
Tipologia: Versione Editoriale (PDF)
Licenza: Tutti i diritti riservati (All rights reserved)
Dimensione 1.31 MB
Formato Adobe PDF
1.31 MB Adobe PDF   Visualizza/Apri   Richiedi una copia
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/3100391
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 88
  • ???jsp.display-item.citation.isi??? 82
social impact