What is the role of Mn/Al/Pt for ZSM-11 being a good catalytic oxidation catalyst?

Catalytic combustion is one of the most effective technologies applied to volatile organic compounds (VOCs) emission control, in which zeolites have been regarded as a unique support or even a catalyst due to their unique shape & size features as well as the interaction between the zeolitic structural groups and the extraneous metal species. Particularly, Mn-based zeolites have attracted great attention as a promising catalyst for their superior redox ability on account of mixed valent properties. In this work, a series of Mn-contained samples with different compositions were synthesized to investigate the role of Al and Mn in zeolite for catalytically combusting VOCs. As redox active sites, Mn is well dispersed in the form of oligomeric Mn oxide clusters on the surface to optimize catalysis. With Al and Mn introduced into zeolite simultaneously, more defects for the activation of adsorbed oxygen appeared on superficial MnO x , but Al prevented Mn being incorporated in ZSM-11(MEL) distinctly, which is a principal factor affecting the catalytic activity . Additionally, Pt was introduced to further enhance the catalytic performance, whose function in Mn-MEL was also clarified in detail via XPS and other characterization techniques. Results demonstrated that appropriate Mn/Pt ratio could create suitable surface morphology (the interface of Pt-MnO x ) for the adsorption of oxygen species via the synergistic catalytic effect caused by Pt and Mn.