Ethanol oxidation on modified clays supported vanadium catalysts

CASUSCELLI, SANDRA GRACIELA; SABRE, EMA VIRGINIA; CORTÉS CORBERÁN, VICENTE; CÁNEPA, ANALÍA LAURA

Cadiff

Congreso; 9th World Congress on Oxidation Catalysis: Oxidation for a Sustainable Future and Clean Environment; 2022

Vanadium catalysts (0.25-2 wt.% V) were prepared by wet impregnation of Ti-pillared clay (Ti-PILC) prepared from a bentonite with an acid Ti(OBu)4 pillaring solution, and tested for EtOH selective oxidation at 250-400 ºC using EtOH:O2 ratios 0.5-1.5 in a continuous flow packed reactor with on line analysis of reactants and products by GC. All their XRD patterns showed no peaks related to V2O5 phase, indicating high V dispersion, and the loss of regularity of the laminated structure of the Ti-PILC during impregnation. However, though specific surface area (SSA) of the starting Ti-PILC (183 m2/g) decreased with increasing V content, all the catalysts kept high SSAs (145-89 m2/g). All catalysts were active and highly selective to AcH (85-93%) in the whole temperature range explored. Despite the SSA decrease, EtOH conversion increased with increasing V content up to 1 wt.% with just a slight further change increasing it up to 2 wt.%, which agrees with a high V dispersion. Conversion increased markedly with increasing temperature and using EtOH:O2=1 the maximum (87%) was observed at 350ºC on 2%V/Ti-PILC, with 82% AcH selectivity (SAcH). On this catalyst we studied the effect of oxygen content in the feed. Though stoichiometric ratio is EtOH:O2=0.5, increasing this ratio up to 1 increased activity by 20% while decreasing SAcH only 4 percentage points. Further increase of oxygen up to EtOH:O2=1.5 had little effect on conversion and SAcH at 300 ºC but decreased slightly SAcH at 350ºC. Optimizing the contact time, a maximum AcH yield of 74% with SAcH = 85% was reached at 350ºC. These results show the feasibility of using easily available clays as sustainable support precursors for efficient vanadium catalysts.