Use of molecular sieves in photocatalytic conversion of CO2 and water to oxygenated organic compounds

Author(s)

Eliane Ribeiro Januario

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Química
• Defense date: 2018-03-09

Examining board members

Heloise de Oliveira Pastore; Dilson Cardoso; Leandro Martínez; Daniela Zanchet; Celso Aparecido Bertran

• Advisor: Heloise de Oliveira Pastore

Abstract

This study aimed at the use of molecular sieves as support for semiconductor nanoparticles to convert CO2 and water into oxygenated molecules using only solar irradiation. Molecular sieves as MCM-41, MCM-48, SBA-15 were used; Mesoporous Carbon Ceramic (CCM¿s)-based on molecular sieves and microporous titanosilicate ETS-10 as supports. The materials were decorated with TiO2, CdS, CuO and Cu2O nanoparticles and applied as photocatalysts. ETS-10 had the pores impregnated with amorphous carbon in order to improve the electron-transfer to the products. The composites were used in photocatalytic reactions of water and CO2 under irradiation for 20 h. The gas and liquid phases were analyzed by different gas chromatography techniques. The following products were observed: oxygen, acetic acid, formaldehyde and methanol. On MCM-41-based materials a higher CO2 conversion was obtained, a fact associated with the higher surface area values that promote better nanoparticles dispersion. MCM-41/CuO 5% showed the highest conversion of CO2 into methanol (5.02%) associated also with the optimal composite band gap for promoting the formation of methanol. In another way, CCM¿s-based materials showed a higher conversion of CO2 into acetic acid and formaldehyde, due to the fact that graphite surface contains a large number of functional groups capable of retaining the products thus avoiding further transformations, as shown by XPS tecnique. ETS-10 based materials showed lower conversion of CO2 than molecular sieves, probably because these materials had lower surface area values. It is noteworthy that the interaction between CuO/Cu2O nanoparticles and TiO2 wires present in ETS-10 structure, proven by spectroscopic techniques. The results showed that the conversion of CO2 and water into oxygenated molecules using irradiation is possible only in the length of sunlight (AU)

• FAPESP's process: 12/08904-3 - Use of molecular sieves in photocatalytic conversion of CO2 and water in hydrocarbon fuels
• Grantee: Eliane Ribeiro Januário
• Support Opportunities: Scholarships in Brazil - Doctorate