Insight into reaction pathways in CO hydrogenation reactions over K/MoS₂ supported catalysts via alcohol/olefin co-feed experiments

Abstract

Reaction pathways for higher alcohol synthesis from syngas are studied over K/MoS2 domains supported on mesoporous carbon (C) and mixed MgAl oxide (MMO) via addition of methanol, ethanol, and ethylene co-feeds.

Assessing C3–C4 alcohol synthesis pathways over a MgAl oxide supported K/MoS2 catalyst via 13C2-ethanol and 13C2-ethylene co-feeds

“…The XRD patterns of the reaction-aged catalysts are shown in Table S2 shows the BET surface areas calculated from N 2 physisorption data (P/P 0 of 0.06-0.2) for the reaction-aged catalysts studied. The BET surface areas for the reaction-aged MoKMMO catalysts vary between 48 m 2 g -1 -63 m 2 g -1 for co-feed experiments, similar to the reaction-aged catalysts without exposure to a co-feed [38]. As observed in previous work, the reaction-aged K/bulk-MoS 2 catalysts did not exhibit measurable porosity [38].…”

“…S4), suggesting that the co-feeds did not cause any significant change in the catalysts. It is important to note that 13 C co-feed experiments led similar product distributions to those obtained with unlabeled co-feed experiments, as previously reported [38].…”

“…K/bulk-MoS 2 was used as a control catalyst subject to 13 C 2 -ethylene co-feed, with an emphasis on understanding the role of K/MoS 2 and K/MoS 2 -MMO sites on higher alcohol formation pathways. The K/bulk-MoS 2 catalyst was not subjected to reactions with 13 C 2 -ethanol, as the ethanol co-feed was found to be largely unreactive previously [38]. This study provides an unprecedented level of insight into the reaction pathways to higher alcohols from syngas over MMO supported K/MoS 2 catalysts.…”

“…However, limited understanding of reaction pathways over supported K/MoS 2 catalysts is available due to the complexity of the catalyst and reaction mechanism(s). Previous work in our group showed that Mo-support interactions directly affect the higher alcohol product distribution [35][36][37][38], with hydrotalcite-derived mixed MgAl oxide (MMO) supports containing small K/MoS 2 domains (predominantly double MoS 2 layers) yielding high C 2+ OH selectivity. Changes in product distribution over the MMO supported K/MoS 2 catalyst via ethanol and ethylene co-feeds provided insight into reaction pathways.…”

“…Changes in product distribution over the MMO supported K/MoS 2 catalyst via ethanol and ethylene co-feeds provided insight into reaction pathways. [38] CO insertion was hypothesized to be the primary pathway to higher alcohols over the MMO supported catalyst. Similar C 3+ OH production rates over the MMO supported catalyst with ethanol and ethylene co-feed experiments indicated that alcohol formation with ethanol co-feed likely proceeded via the same acyl intermediate as olefin carbonylation.…”