Single Atom Catalysis for Improved Hydrogenation Selectivity

In heterogeneous catalysis, selectivity has become the most important issue because undesired or even harmful by-products and energy-consuming separation processes have to be avoided. 1-butene is a major feedstock for producing a variety of polymers, but the industry feed usually contains small amounts of 1 - butyne, poisoning the polymerization process. Selective hydrogenation of 1-butyne to 1-butene, avoiding isomerization to trans-2-butene and cis-2-butene as well as hydrogenation to n-butane, is key. Derivatives of aminoalkylfuran make up a large class of biologically active compounds and are widely used as pharmaceuticals. Therefore, the development of efficient and ecologically sound methods of aminoalkylfuran production is of great interest. 5-hydroxymethylfurfurol obtained from the generally available non-edible lignocellulosic biomass is a perfect initial material for synthesis of this class of compounds by selective reductive amination. However, for both applications highly selective hydrogenation catalysts are required. Heterogeneous catalytic systems, in which all active sites are identical and have equal energy, are so- called single atom (single-site) heterogeneous catalysts. The equivalence of the active sites leads to significantly higher selectivity of catalytic transformations. In this collaborative project between TU Wien (TUW) and Boreskov Institute of Catalysis (BIC), we will utilize single atom catalysts, specifically single Pd (or Pt) atoms surrounded by less active Au (or Ag) atoms, for the selective isomerization and hydrogenation of 1-butyne and 1-butene, as well as for aminoalkylfuran production. The site is olation of single Pd (Pt) atoms (avoiding larger Pd (Pt) ensembles) is expected to influence strongly the intermediates and thus the selectivity and coking resistance of the active sites. Note that typically active sites comprising two or more neighboring Pd (Pt) atoms are required for C-C bond cleavage. The des ired cataysts will be realized by growing bimetallic PdAu (PtAu) or PdAg (PtAg) nanoparticles (clusters) on alumina supports, and characterized by various physical and theoretical surface science methods. We will employ a three-fold approach, using (i) surface science based model catalysts, (ii) industrial grade high surface area catalysts and (iii) computational modeling. Both research groups are well-experienced in these fields but the group at TUW will focus on model catalysts, while the group at BIC will address industrial catalysts. Similarly, this complementary experimental approach will be paralleled by complementary computational modeling (DFT), focusing on single crystals (slab models) in Vienna and on clusters and nanoparticles in Novosibirsk. Only this joint effort will deliver fundamental insight on the structure and properties of single atom catalysts with improved stability and selectivity, enabling us to transfer the new knowledge to industrial applications faster.

TU Vienna press release: https://www.tuwien.at/en/tu-wien/news/news-articles/news/zweihundertfach-bessere-katalysatoren-durch-kohlenstoff