Enhancing the stability of Cu-SiO2 catalysts prepared by aerosol-assisted sol-gel for ethanol dehydrogenation to acetaldehyde reaction

Details

Supervisors

Debecker, Damien P.

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en chimie et bioindustries, à finalité spécialisée

Abstract

The increasing global energy demand, coupled with the depletion of fossil resources, necessitates a transition towards renewable sources to produce essential chemicals. Bioethanol, derived from biomass fermentation, emerges as a significant sustainable chemical platform. This thesis focuses on the non-oxidative dehydrogenation of ethanol to acetaldehyde, an industrially crucial reaction that produces acetaldehyde and hydrogen, resulting in significant economic and environmental benefits. The primary objective of this research is to enhance the stability of Cu-SiO₂ catalysts prepared by the aerosol-assisted sol-gel (AASG) process for the ethanol dehydrogenation reaction. The main challenge addressed is the deactivation of the catalysts due to sintering and coking. To mitigate these issues, the study explores the integration of (3 Mercaptopropyl)trimethoxysilane (MPTMS), a stabilizer, into the catalyst synthesis. The Cu-SiO₂ catalysts were prepared in a single step using the aerosol-assisted sol-gel technique, varying the Cu/MPTMS molar ratio (1:0, 2:1, 1:1, 1:2). The catalysts were characterized using several techniques, including nitrogen physisorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR), UV-visible spectroscopy, inductively coupled plasma atomic emission spectroscopy (ICP-AES), and X-ray photoelectron spectroscopy (XPS). Catalytic tests revealed that MPTMS-containing catalysts exhibited better stability and increased resistance to deactivation compared to catalysts without MPTMS. Notably, the molar ratio (1:1) catalyst demonstrated higher ethanol conversion rates with great acetaldehyde selectivities over extended periods, effectively reducing sintering. This enhanced stability is attributed to the partial embedding of copper particles within the silica matrix, which protects the particles from sintering when adding MPTMS. Long-term stability tests confirmed that catalysts containing MPTMS deactivated less than those without, even at high temperatures. In conclusion, incorporating MPTMS during the synthesis of Cu/SiO₂ catalysts via the AASG method significantly enhances their stability, promising a more sustainable production of acetaldehyde from ethanol. Future research should address identified limitations and explore further improvements to ensure industrial viability and large-scale application.