Ptpdconicu/Tio2 High-Entropy Alloy Catalyst for Synthesis of Γ-Butyrolactone by Selective Hydrogenation/Hydrogenolysis of Maleic Anhydride

Abstract

The continuous flow selective hydrogenation of maleic anhydride (MA) to γ-butyrolactone (GBL) over highly efficient and long-term stable catalysts is a considerable promising strategy for both lab-scale as well as industrial application. In this work, a PtPdCoNiCu/TiO2 high-entropy alloy (HEA) catalyst is developed by the colloidal impregnation method, in which the HEA colloids are synthesized by lithium naphthalenide-driven reduction at mild conditions according to the redox potential of the various metals. The PtPdCoNiCu/TiO2 catalyst exhibits highly efficient in the selective hydrogenation of MA with 91% selectivity to GBL at full conversion of MA under the weighted hourly space velocity of 1.14 h-1, 3 MPa, and 260 oC. Due to the present of oxygen vacancy in the TiO2 support and the hydrogen spillover, the PtPdCoNiCu/TiO2 HEA catalyst presents a low apparent activation energy (75 kJ mol−1), boosting the hydrogenolysis of C=O bonds for generating of GBL. The cocktail effect is presented in the PtPdCoNiCu/TiO2 catalyst, and its catalytic activity is much better than that of corresponding monometallic and bimetallic catalysts. It realizes the reduction and substitution of precious metal catalysts. In addition, the PtPdCoNiCu/TiO2 catalyst with sintering resistance and acid resistance shows excellent long-term stability within 132 h. This work is of great significance for understanding HEA catalysis at the atomic level and provides the possibility for developing low-cost and efficient precious metal industrial catalysts.

Keywords: High-entropy alloy, Hydrogenation, Hydrogenolysis, Hydrogen spillover, Maleic anhydride, γ-Butyrolactone