THE DEVELOPMENT OF CU/TIO2/ZSM-5 CATALYSTS FOR PHOTOCATALYTIC CO2 REDUCTION TO METHANOL

• Main Author: Satriyatama, Adhi
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/66192
• Institution: Institut Teknologi Bandung

Titanium dioxide (TiO2) is currently the most widely investigated material as a photocatalyst because of its high stability, low cost, and good photocatalytic capabilities. However, limitations in low light absorption on visible light and high bandgap energy (~3.2 eV) make modification strategies should be employed to improve photocatalytic activity. This study examined the effects of calcination temperature and copper doping of TiO2/ZSM-5 for photocatalytic CO2 reduction to methanol. The catalyst synthesis approach comprised four key stages: (a) wet-impregnation synthesis of titanium-impregnated ZSM-5, (b) air-calcining titanium-impregnated ZSM- 5 which was varied from 400 – 800 oC to produce TiO2/ZSM-5, (c) wet-impregnation synthesis of Cu-impregnated TiO2/ZSM-5, (d) air calcination to produce CuO/TiO2/ZSM-5 or Cu reduction using NaBH4 and followed by air calcination to produce Cu/TiO2/ZSM-5. The calcination temperature was varied from 400 – 800 oC.. This method produced TiO2/ZSM-5 particles with a high (~19 wt. %) Ti loading, which confirmed from XRF analysis. Based on XRD spectra, the presence of rutile (~44 wt. %) was found under temperature of 800 oC, indicating that anatase-to-rutile transition occurred at above 600 oC. However, UV-vis analysis reveals that band gap value was extended due to the small-scale effects of Ti nanomaterials. Textural analysis that was done using N2 adsorption/desorption isotherm highlights the type-IV isotherm with high surface area (~305 m2/g). All TiO2-introduced ZSM-5 samples were shown 3-fold higher of methanol yield (~0.3 mmol/g.cat). After Cu was introduced to TiO2/ZSM-5, methanol yield increased significantly to 0.55 mmol/g.cat, which achieved by CuO/TiO2/ZSM-5. These results indicated that depositing copper to the catalyst increases the visible light absorption, as evidenced by UV-vis DRS spectra. In addition, the presence of copper can be confirmed via SEM-EDX mapping and XRF, showing the Cu concentration was around 2 wt.% with homogeneous dispersion in the surface, although it cannot be determined from XRD pattern.