Properties and bifunctional catalytic activity of niobium-doped silica-titania: effect of phosphoric acid treatment

• Main Authors: Lee, Siew Ling, Mohd. Ekhsan, Jamilah, Ling, Chui Min
• Format: Article
• Language: English
• Published: Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya 2022
• Subjects: QD Chemistry
• Online Access: http://eprints.utm.my/id/eprint/98798/1/LeeSiewLing2022_PropertiesandBifunctionalCatalyticActivity.pdf; http://eprints.utm.my/id/eprint/98798/; http://dx.doi.org/10.26554/sti.2022.7.4.455-460
• Institution: Universiti Teknologi Malaysia

The effect of phosphoric acid treatment on the physical-chemical properties and catalytic activity of the niobium-doped silica-titania bifunctional catalyst was investigated. As part of the synthesis procedure to produce xPO4−/Nb/TiO2-SiO2, different concentrations of phosphoric acid (H3PO4) were used (x= 0, 0.05, 0.10, 0.15, 0.20, 0.25 M). As shown by XRD analysis, the samples synthesized using 0–0.20 M H3PO4 were in amorphous form, as featureless diffractograms were obtained, indicating the PO4− groups were dispersed homogeneously on the surface of Nb doped SiO2-TiO2 . Due to the increased concentration of acid, other compounds were formed in the samples by reactions between PO4− and Nb and/or Ti. Additionally, UV-Vis DRS results indicated that the presence of the PO4− group accelerated the transformation of hydrated tetrahedral Ti species into isolated tetrahedral Ti species. An experimental investigation of the catalytic performance of the catalyst was conducted using 1,2-epoxyoctane as an oxidant for the epoxidation of 1-octene to 1,2-octanediol. It has been demonstrated that H3PO4 treatment was essential for oxidative and acidity active site formation. The current research findings strongly suggested that Nb-doped TiO2-SiO2 treated with 0.2 M H3PO4 was the most effective bifunctional catalyst in generating 1,2-octanediol.