Multifunctional Carbon‐Nanotube Supported Catalyst for Efficient Glycerol Hydrogenolysis to 1,2‐propanediol

ABSTRACT Multiwall carbon nanotube (NC7000) supported mono‐, bi‐, and trimetallic catalysts were synthesized and tested in a multi‐batch reactor setup supported by data‐driven modeling for the chemical hydrogenolysis of glycerol to 1,2‐Propanediol (1,2‐PDO) at 220°C under 30 bar hydrogen pressure in aqueous solution. ICP‐OES, N 2 ‐physisorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive x‐ray spectroscopy (EDX), powder x‐ray diffraction (XRD) and x‐ray photoelectron spectroscopy (XPS) were used to investigate the physico‐chemical properties of the synthesized catalysts. Interesting structure‐activity‐selectivity correlations could be deduced from the different metal ratios and combinations. While Ru was by far the most active monometallic species ( X = 100%), followed by Pt ( X = 80%) and Ir ( X = 65%), it suffered from a very low 1,2‐PDO selectivity ( S < 10%). Combining Ru with the more selective transition‐metals RuX 2 ( X = Fe, Co, or Ni) maintained the high activity ( X > 95%) but only moderately increased 1,2‐PDO selectivity ( S = 20%–30%). Interestingly, combining Ru with Cu in a bimetallic RuCu 2 catalyst slightly decreased activity ( X = 81%) but drastically improved 1,2‐PDO selectivity ( S = 58%). Moreover, a trimetallic combination of RuMCu 2 (M = Pt, Pd, Ir) did not further increase activity ( X = 50%–70%) but could push 1,2‐PDO selectivity up to 79% for the trimetallic RuIrCu 2 catalyst. Most prominently, a final metal ratio variation for the RuCu x catalyst was derived with the help of the data‐driven models producing the most promising RuCu 3 /NC7000) catalyst combining both high activity ( X = 78%) with a very high 1,2‐PDO selectivity ( S = 79%) resulting in the highest 1,2‐PDO yield of 58% in a nearly closed carbon balance ( C > 95%). This lays the foundation for implementing this highly active and selective catalyst in a future SMART reactor for glycerol valorization.