SYNTHESIS AND CHARACTERIZATION OF BI2MOO6 NANOPARTICLES AS PHOTOCATALYST FOR TOLUENE OXIDATION TO BENZALDEHYDE

• Main Author: Indra Christianto, Jonathan
• Format: Final Project
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/54788
• Institution: Institut Teknologi Bandung

Toluene is the organic compund that has been widely used as precursor to produce another aromatic compounds, one of them is benzaldehyde. Besides benzaldehyde, oxidation of toluene will produce benzyl alcohol and benzoic acid. Oxidation of toluene to benzaldehyde with conventional methods have some drawbacks, such as unavoidable over-oxidation, formation of pollutants, low selectivity, and more complex synthesis processes. Therefore, photocatalyst is needed to overcome these drawbacks. Bi2MoO6 (bismuth molybdate) is considered as the promising photocatalyst, because the CBM and VBM values are suitable for oxidation of toluene to benzaldehyde without further oxidation to produce benzoic acid. Besides Bi2MoO6, there are two other main phases of bismuth molybdate: Bi2Mo2O9 and Bi2Mo3O12. Bi2MoO6 could be synthesized by hydrothermal/solvothermal method to obtain Bi2MoO6 with desired morphology. From the study of Bi2MoO6 crystal structure, it is known that Bi2MoO6 adopts Aurivillius structure with distorted MoO6 octahedral layer. Octahedral layer distortion may be caused by the octahedral rotation or tilting of O atoms at the apices of the octahedra, due to the formation of O atoms of octahedral apices with Bi atom. These distortions will cause the formation of VO•• crystal defect, which acts as electron trap. From the study of morphology of Bi2MoO6, it is known that morphology of as-synthesized Bi2MoO6 is affected by pH, solvent, reaction temperature and time. Bi2MoO6 with 2- dimension morphology and exposed [010] facet is the desired form of photocatalyst. From the study of reaction mechanism of oxidation of toluene to benzaldehyde, it is known that oxidation of toluene to benzaldehyde will involve electron and hole. Hole will act as main active species. Hole will either react directly with toluene or react with water to produce •OH. Water presence in reaction system will give a positive effect as source of •OH and negative one since it competes with toluene adsorption on Bi2MoO6 surface. Bi2MoO6 synthesis has been carried out with Bi/Mo molar ratio of 1/1, 2/1, 3/1, and 4/1. The obtained products are then characerized by XRD (X-ray diffaction). Rietveld refinement analysis shows that sample with Bi/Mo molar ratio of 2/1 contains Bi2MoO6 with the highest mass fraction. Crystallinity and particles size analysis shows that crystallinity and particles size of the samples increase as Bi/Mo molar ratio increases up to 3/1 ratio.