Mesoporous MnO<inf>2</inf> hollow spheres for enhanced catalytic oxidation of formaldehyde
MetadataShow full item record
© 2018 In this work, hollow MnO2 spheres were synthesized via a sacrificial templating method using SiO2 nanospheres as hard templates. The MnO2 coating on SiO2 was achieved by a newly devised low-temperature, controlled precipitation by redox (CPR) method which is based on the controlled redox reaction between KMnO4 and Mn(NO3)2 at 30 °C. After calcination of the SiO2@MnO2 core shell spheres at 300 °C, hollow spheres were obtained following template removal by NaOH etching. The hollow spheres were characterized by XRD, Raman spectroscopy, TEM, HRTEM, N2 adsorption, XPS and H2-TPR. Two different MnO2 crystal phases (?- and d-MnO2) could be obtained by making simple changes in the precursor addition protocols during synthesis. All the samples had high BET surface areas between 104 m2 g-1 and 236 m2 g-1, hierarchical pore size distribution with high mesoporosity and the presence of oxygen vacancies for high mobility of oxygen species on the catalyst surface. The catalysts were used for the complete catalytic oxidation of formaldehyde in dry air (100 ppmv; GHSV: 30,000 h-1). Long-term stability tests showed that ?-MnO2 deactivated gradually with time potentially due to structural collapse of the hollow spheres. The interlayer spacing in the d-MnO2 sample, however, was responsible for increasing the expected conversion due to the regeneration of oxygen/hydroxyl species from adsorbed water formed from the oxidation of formaldehyde on the catalyst surface.
Showing items related by title, author, creator and subject.
Zhang, X.; Liu, T.; Sun, W.; Liu, Jian (2013)Hierarchical mesoporous organosilicas with hollow structures have been readily synthesized from one template approach by using Pluronic P123 as a surfactant and 1,2-bis(trimethoxysilyl)ethane as precursor in mild HAc-NaAc ...
Insight into the mechanism of photocatalytic degradation of gaseous o-dichlorobenzene over flower-type V2O5 hollow spheresLiu, B.; Li, Xin Yong; Zhao, Q.; Liu, J.; Liu, Shaomin; Wang, S.; Tadé, M. (2015)This work aims to explore the mechanism of photocatalytic degradation of gaseous 1,2-dichlorobenzene (o-DCB) over vanadium pentoxide (V2O5) hollow spheres. To this end, flower-type V2O5 hollow microspheres with diameters ...
Synthesis and characterisation of silica-polymer hybrid core-shell and hollow spheres for drug delivery applicationsLou, Xia; Schumacher, T.; Yang, H.; Ding, Ailin (2011)Silica-polymer hybrid core-shell structures and nano-hollow spheres with chemically immobilized hydrophobic, hydrophilic, and thermal sensitive functional groups on the surfaces were prepared through a simple synthetic ...