Exploring the Multifunctionality of Mechanochemically Synthesized γ-Alumina with Incorporated Selected Metal Oxide Species

Rabindra Dubadi; Ewelina Weidner; Bogdan Samojeden; Teofil Jesionowski; Filip Ciesielczyk; Songping Huang; Mietek Jaroniec

doi:10.3390/molecules28052002

Exploring the Multifunctionality of Mechanochemically Synthesized γ-Alumina with Incorporated Selected Metal Oxide Species

Molecules. 2023 Feb 21;28(5):2002. doi: 10.3390/molecules28052002.

Authors

Rabindra Dubadi¹, Ewelina Weidner², Bogdan Samojeden³, Teofil Jesionowski², Filip Ciesielczyk², Songping Huang¹, Mietek Jaroniec¹

Affiliations

¹ Department of Chemistry and Biochemistry, Kent State University, Kent, OH 44242, USA.
² Institute of Chemical Technology and Engineering, Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, PL-60965 Poznan, Poland.
³ Department of Fuel Technology, Faculty of Energy and Fuels, AGH-University of Science and Technology, Al. A. Mickiewicza 30, PL-30059 Krakow, Poland.

Abstract

γ-Alumina with incorporated metal oxide species (including Fe, Cu, Zn, Bi, and Ga) was synthesized by liquid-assisted grinding-mechanochemical synthesis, applying boehmite as the alumina precursor and suitable metal salts. Various contents of metal elements (5 wt.%, 10 wt.%, and 20 wt.%) were used to tune the composition of the resulting hybrid materials. The different milling time was tested to find the most suitable procedure that allowed the preparation of porous alumina incorporated with selected metal oxide species. The block copolymer, Pluronic P123, was used as a pore-generating agent. Commercial γ-alumina (S_BET = 96 m²·g^-1), and the sample fabricated after two hours of initial grinding of boehmite (S_BET = 266 m²·g^-1), were used as references. Analysis of another sample of γ-alumina prepared within 3 h of one-pot milling revealed a higher surface area (S_BET = 320 m²·g^-1) that did not increase with a further increase in the milling time. So, three hours of grinding time were set as optimal for this material. The synthesized samples were characterized by low-temperature N₂ sorption, TGA/DTG, XRD, TEM, EDX, elemental mapping, and XRF techniques. The higher loading of metal oxide into the alumina structure was confirmed by the higher intensity of the XRF peaks. Samples synthesized with the lowest metal oxide content (5 wt.%) were tested for selective catalytic reduction of NO with NH₃ (NH₃-SCR). Among all tested samples, besides pristine Al₂O₃ and alumina incorporated with gallium oxide, the increase in reaction temperature accelerated the NO conversion. The highest NO conversion rate was observed for Fe₂O₃-incorporated alumina (70%) at 450 °C and CuO-incorporated alumina (71%) at 300 °C. The CO₂ capture was also studied for synthesized samples and the sample of alumina with incorporated Bi₂O₃ (10 wt.%) gave the best result (1.16 mmol·g^-1) at 25 °C, while alumina alone could adsorb only 0.85 mmol·g^-1 of CO₂. Furthermore, the synthesized samples were tested for antimicrobial properties and found to be quite active against Gram-negative bacteria, P. aeruginosa (PA). The measured Minimum Inhibitory Concentration (MIC) values for the alumina samples with incorporated Fe, Cu, and Bi oxide (10 wt.%) were found to be 4 µg·mL^-1, while 8 µg·mL^-1 was obtained for pure alumina.

Keywords: CO2 capture; NO conversion; antimicrobial properties; mechanochemical synthesis; metal oxide incorporation; γ-alumina.

Grants and funding

This research received no external funding.