[EN] Tungsten oxide bronze-based materials show extremely adaptive structural and compositional features that make them suitable for functional properties modulation. Herein we report the preparation of a series of ...[+]
[EN] Tungsten oxide bronze-based materials show extremely adaptive structural and compositional features that make them suitable for functional properties modulation. Herein we report the preparation of a series of Ti-containing tungsten oxide catalysts presenting a hexagonal tungsten bronze-type structure. The insertion of Ti4+ within the structure (likely in the octahedral framework of the hexagonal tungsten bronze) leads to an increase in the number of strong acid sites, and the disappearance of W5+ surface species found in the undoped tungsten oxide. With the aim of studying the acid-redox properties of the titled catalysts, the catalytic transformation of methanol has been carried out in the presence and the absence of O-2 in the feed. Both catalytic activity and the acid-redox properties of these catalysts are highly dependent on catalyst composition and reaction conditions applied (i.e. in the presence or in the absence O-2 in the feed). Aerobic experiments show the depletion of the redox functionality (i.e. no formaldehyde detected in the products) when Ti4+ is incorporated in the framework (i.e. 100% selectivity to dimethyl ether). On the other hand, all the catalysts show the loss of the redox function and a decrease in the catalytic activity when anaerobic conditions are used. In the absence of oxygen, the catalysts are still active in the dehydration of methanol to dimethyl ether, i.e. they maintain their acid functionality even when oxygen is not present in the feed. The results are discussed in terms of the available surface active sites present in each case.[-]
MINECO/SVP-2014-068669 MINECO/MAT2017-84118-C2-1-R Ministerio de Economia y Competitividad/CTQ2015-68951-C3-1-R Comisión Interministerial de Ciencia y Tecnología /RTI2018-099668-B-C21 MINECO/SEV-2016-0683
Thanks:
Authors would like to thank DGICYT in Spain for RTI2018-099668-B-C21, CTQ2015-68951-C3-1-R and MAT2017-84118-C2-1-R projects. Authors from ITQ also thank Project SEV-2016-0683 for supporting this research. D.D. thanks ...[+]
Authors would like to thank DGICYT in Spain for RTI2018-099668-B-C21, CTQ2015-68951-C3-1-R and MAT2017-84118-C2-1-R projects. Authors from ITQ also thank Project SEV-2016-0683 for supporting this research. D.D. thanks MINECO and Severo Ochoa Excellence Program for his fellowship (SVP-2014-068669). Finally, authors thank the Electron Microscopy Service of SCSIE of Universitat de Valencia for their support.[-]