Stepwise methane to methanol conversion: Effect of copper loading on the formation of active species in copper-exchanged mordenite

Author(s)

Mizuno, Stefanie C. M. ^[1] ; Dulnee, Siriwan ^[1] ; Pereira, Tassia C. P. ^[1] ; Passini, Ricardo J. ^[1] ; Urquieta-Gonzalez, Ernesto A. ^[1] ; Gallo, Jean Marcel R. ^[2] ; Santos, Joao B. O. ^[1] ; Bueno, Jose M. C. ^[1]

Affiliation

^[1] Univ Fed Sao Carlos, Dept Chem Engn, Rod Washington Luis, Km 235, CP 676, BR-13565905 Sao Carlos, SP - Brazil

^[2] Univ Fed Sao Carlos, Dept Chem, Renewable Energy Nanotechnol & Catalysis Grp Gree, Rod Washington Luis, Km 235, CP 676, BR-13565905 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: CATALYSIS TODAY; v. 381, p. 13-25, DEC 1 2021.
• Web of Science Citations: 0

Abstract

This work investigates the influences of Cu content, Si/Al ratio, and sample preparation method on the active Cu species in mordenite (MOR). The Cu/MOR prepared by multiple Cu-exchange procedures showed an optimum Cu/Al ratio for the formation of the most active species for methanol formation. XANES spectra indicated that isolated Cu+ species were formed after CH4 interaction and were re-oxidized under a flow of water steam. The Cu-MOR samples obtained by ion-exchange method presented well-dispersed CuO in the zeolite pores, while samples obtained by impregnation method presented segregated CuO and were inactive for CH4 activation. The methodology used for in situ UV-vis spectra analyses indicated that different Cu species were active for CH4 oxidation. Isolated Cu2+ species were not involved in CH4 activation at temperatures lower than 300 degrees C. The isolated Cu2+ species were partially hydrolyzed by O-2 treatment and species like {[}CuOH](+) and {[}CuOx](n) or polynuclear Cu2+-oxyhydroxide were formed. The formation of polynuclear species in substitution of di-copper would impact the specific activity with the Cu content and decrease the activity for methanol production. (AU)

• FAPESP's process: 16/02128-2 - Design of new catalytic systems for the biorefinery
• Grantee: Jean Marcel Ribeiro Gallo
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 18/26459-3 - Zeolites exchanged with CuxOy single sites for the methane partial oxidation to methanol: the effect of zeolite structure and other metal oxides in the single site activity
• Grantee: Tássia Caroline Passos Pereira
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 18/01258-5 - Novel chemical catalytic and photocatalytic processes for the direct conversion of methane and CO2 to products
• Grantee: José Maria Correa Bueno
• Support Opportunities: Research Projects - Thematic Grants