Unravelling the K-promotion effect in a highly active and stable Fe5C2 nanoparticle for catalytic linear alpha-olefin production

C5−C13 linear alpha() olefins (LAOs) are high-value-added chemicals acknowledged by industry. However, using catalysts to elevate the activity and selectivity of LAOs remains a major challenge for Fischer–Tropsch synthesis (FTS)....

Impact of Small Promoter Amounts on Coke Structure in Dry Reforming over Ni/ ZrO2

Coke deposition is one of the main challenges in the commercialization of dry reforming of methane over supported Ni catalysts. Besides the coke quantity, the structure of the deposits is also essential for the catalyst lifetime. Accordingly, in this study, we analysed the effect of different metal promoters on both these variables over Ni/ ZrO₂ catalysts. Alkali metals are known to block the most active coke forming sites already at low loading, leading to an investigation of Na, K and Cs. To analyse the possible contributions of coke gasification activity of the alkali metals, Mn was additionally used as a comparison. While the conversion is barely affected by the type of promoter, it has profound effect on the amount and the composition of carbon deposits formed during reaction: Addition of K or Mn reduces the coke content to a similar degree but with less carbon fibres observed in the case of K. Promotion by Cs and Na results in the lowest coke content, which is attributed to enhanced coke gasification via carbonate species

Resonance in orbits of plane partitions

International audience We introduce a new concept of resonance on discrete dynamical systems. Our main result is an equivariant bijection between plane partitions in a box under rowmotion and increasing tableaux under K-promotion, using a generalization of the equivariance of promotion and rowmotion [J. Striker–N. Williams '12] to higher dimensional lattices. This theorem implies new results for K-promotion and new proofs of previous results on plane partitions.

Promotion of Increasing Tableaux: Frames and Homomesies

A key fact about M.-P. Schützenberger's (1972) promotion operator on rectangular standard Young tableaux is that iterating promotion once per entry recovers the original tableau. For tableaux with strictly increasing rows and columns, H. Thomas and A. Yong (2009) introduced a theory of $K$-jeu de taquin with applications to $K$-theoretic Schubert calculus. The author (2014) studied a $K$-promotion operator $\mathcal{P}$ derived from this theory, but observed that this key fact does not generally extend to $K$-promotion of such increasing tableaux. Here, we show that the key fact holds for labels on the boundary of the rectangle. That is, for $T$ a rectangular increasing tableau with entries bounded by $q$, we have $\mathsf{Frame}(\mathcal{P}^q(T)) = \mathsf{Frame}(T)$, where $\mathsf{Frame}(U)$ denotes the restriction of $U$ to its first and last row and column. Using this fact, we obtain a family of homomesy results on the average value of certain statistics over $K$-promotion orbits, extending a $2$-row theorem of J. Bloom, D. Saracino, and the author (2016) to arbitrary rectangular shapes.