Influence of acid-metal functions on product distribution in valorization of biomass-derived acetone and catalysts’ deactivation behaviour

Abstract

Availability of acetone from processes such as phenol manufacturing and that from biomass fermentation offers an impetus to look for ways out to value added chemicals as acetone as such on its own little profit. The techniques towards this include its hydrogenation/aldolization, alkylation, etc. In this work, the former is dealt with. To exploit previously established enhanced hydrogen spillover on multi-walled carbon nanotubes (MWCNT), 0.5 wt% Pd was impregnated on MWCNT. This afforded chiefly hydrogenation product iso-propyl alcohol, and very little of methyl isobutyl ketone (MIBK) was observed. A product of successive aldolization, diiso butyl ketone (DIBK), was totally absent. This catalyst afforded higher acetone conversions at higher operating pressures. Also, there was no sign of catalyst deactivation with time-on-stream. However, when this catalyst was physically mixed with an acid catalyst HZSM-5 in equal mass proportion (thus, reducing Pd content to 0.25 wt%), acetone aldolization reaction took over its hydrogenation, and MIBK and DIBK were the main products. This catalyst showed a slow rate of deactivation. Further, when this latter catalyst was modified by impregnating it with 5 wt% Cu to provide a synergistic effect for hydrogenation reaction, as reported in the literature, this modification afforded 10 wt% point enhancement of IPA+MIBK+DIBK yields over the previous catalyst thanks to higher acetone conversions. It also showed slightly less rate of deactivation over the previous catalyst. It is proposed that the rate of deactivation can be reduced employing higher hydrogen to acetone molar ratio in the feed and fine-tuning the acidity of zeolites.