A synergistic catalyst system comprising PtPdCoNiCu/C High-Entropy alloy and H4SiW12O40 for Low-Temperature hydrogenolysis of C–O bonds in Coal-Derived compounds

Abstract

The development of directed hydrogenolysis of coal under mild conditions to yield aromatic compounds signifies a pioneering approach for the non-energy utilization of coal, effectively augmenting the added value of coal-derived products. In this work, a synergistic catalyst system composed of PtPdCoNiCu/C high-entropy alloy (HEA) and H₄SiW₁₂O₄₀ has been formulated for the catalytic hydrogenolysis of C–O bonds in coal-derived compounds and low-rank coal. Due to the high-entropy effect, the PtPdCoNiCu/C catalyst exhibits markedly enhanced catalytic activity in comparison to its monometallic counterparts. The conversion of benzyl phenyl ether achieves an impressive 99.8 %, with yields of toluene (99.8 %) and phenol (99.2 %) at 50 °C and 0.1 MPa H₂ for 2 h. The apparent activation energy (Ea) for this synergistic catalyst system is merely 31.6 kJ/mol, significantly lower than that of the PtPdCoNiCu/C catalyst alone (86.4 kJ/mol), suggesting that hydrogen spillover facilitates the surface hydrogenolysis of C–O bonds. Furthermore, for the hydrogenolysis of benzyl ether and phenoxy ethylbenzene, the synergistic catalyst system demonstrates remarkable efficiency, with Ea values of 58.6 kJ/mol and 100.0 kJ/mol, respectively. The products formed are aromatic compounds, devoid of any over-hydrogenated derivatives. Notably, the cleavage barrier of the aryl C–O bonds is profoundly influenced by the energy associated with the C–O bonds. Additionally, the synergistic catalyst system comprising PtPdCoNiCu/C and H₄SiW₁₂O₄₀ represents a promising catalyst for the hydrogenolysis of Naomaohu coal under mild conditions. This study will establish a foundation for the directed pyrolysis of coal under mild conditions to generate high-end fine chemicals, providing a novel pathway for the clean, low-carbon, and high-value utilization of coal resources.