Role of a Doped Support Strategy for Maintaining Stable Cuⁿ⁺ Sites in Acetylene Hydrochlorination

A Cu-based catalyst, a developable catalyst in the acetylene hydrochlorination reaction, suffers from severe insufficient activity due to the reduction of Cuⁿ⁺ sites under a C₂H₂ atmosphere. In this work, we have developed a doped support strategy to maintain more than 90% of Cuⁿ⁺ sites during the reaction via simply treating the mixture of melamine pyrophosphate and pristine activated carbon. Doped engineering for support plays dual positive roles in the acetylene hydrochlorination reaction: due to the interaction between Cu and doped sites, reduced C₂H₂ molecules are easily desorbed at lower temperatures on the Cu sites to inhibit the reduction from Cuⁿ⁺ to Cu⁰ during the reaction. Besides, element-doped sites also provide more adsorption sites for reactant molecules to decrease the internal diffusion distance. Based on the above benefits, the optimal catalyst (Cu/N,P_1/2-AC) achieved an initial C₂H₂ conversion of 97.8%, and the activity loss of the catalyst was only 14.2% in the long-term stability test at 200 h. Finally, this strategy is extended by other two doped precursors with obvious catalytic performance enhancement. This designed strategy for Cu-based catalysts provides a new appreciation for the acetylene hydrochlorination reaction.