Total oxidation of benzene over cerium oxide-impregnated two-dimensional MWW zeolites obtained by environmental synthesis using Brazilian rice husk silica agro-industrial waste

• Published in: Molecular catalysis 2022-08, Vol.529, p.112529, Article 112529
• Main Authors: Schwanke, Anderson J., Maffi, Gabriela M., Sachse, Alexander, Radtke, Cláudio, Bernardo-Gusmão, Katia, Balzer, Rosana
• Format: Article
• Language: English
• Subjects: Catalysis; Cerium-oxide; Chemical Sciences; Environmental Engineering; Environmental Sciences; ITQ-2; MCM-22; Rice husk silica; Zeolites
• ISSN: 2468-8231; 2468-8231
• DOI: 10.1016/j.mcat.2022.112529

•Sustainable delaminated ITQ-2 zeolite was obtained from rice husk silica (R) for the first time.•At the same Ce content (5%), silica from rice husks (R), MCM-22 and ITQ-2 exhibited cerium oxide NPs size of 7.3, 6.5 and 5.7 nm, respectively.•The ITQ-2 with 5 and 10% of Ce reached higher benzene oxidation (84 and 91%) than MCM-22 (70 and 79%).•The catalytic stability of ITQ-2 and MCM-22 with 10% of Ce was maintained up to the studied period (16 h at 350 °C). This work aimed to obtain sustainable catalysts for environmental catalysis. The ITQ-2 and MCM-22 layered zeolites impregnated with cerium (5 and 10%) were synthesized from a sustainable approach employing silica (R) from low-cost and abundant Brazilian agro-industrial waste, rice husks. The results indicate the type of support, porosity, surface defects and concentration of Ce influenced the size and dispersion of cerium oxide-nanoparticles (NPs). At the same Ce loading (5%), the porosity and surface defects followed the order R (46 m² g−1) < MCM-22 (341 m² g−1) < ITQ-2 (475) m² g−1) and resulted the decrease of NPs size (7.3 > 6.5 > 5.7 nm). The ITQ-2 and MCM-22 containing 10% of Ce resulted in the decrease of porosity of 422 and 329 m² g−1 and the increase of NPs size (7.5 and 8.3 nm), respectively. The DRS UV-Vis and XPS results indicated that Ce4+ and Ce3+species were present in all synthesized materials. The materials were evaluated for the gas-phase total oxidation of volatile organic compound (benzene) as a model reaction to reduce atmospheric pollutants. The best oxidation results were achieved at 350 °C for the Ce-impregnated ITQ-2 (5 and 10% of Ce) reaching benzene conversions of 84 and 91%, respectively, and followed by Ce-impregnated MCM-22 (5 and 10% of Ce) with 70 and 79%, respectively. No loss of activity was observed after 16 h of reaction for both Ce-impregnated ITQ-2 and MCM-22 with 10% of Ce. [Display omitted]