Regulating the location relationship between Cu nanoparticles and Pt atoms to enhance the catalytic hydroisomerization performance: Together or apart?

Abstract

Single atom catalysts have been recently reported as the efficient catalysts for hydroisomerization compared to the conventional nanoparticle catalyst. Despite the fascinating advantage in enhancing the metal activity or reducing the catalyst cost, the long-term stability of the single atom catalyst seemed not that satisfactory, especially when reacting under atmospheric pressure. Herein, Pt single atom catalysts were combined with Cu nanoparticles by different means to explore a new way to improve the catalytic performance. Cu nanoparticles were located away from Pt sites to form a binary catalyst, or acted as the support of Pt atoms to form a single atom alloy (SAA) catalyst. With the binary catalyst Pt₁–0.1Cu@CS, the conversion of the n-heptane after time on stream of 50 h increased to 70.3 %, higher than Pt₁@CS (47.3 %). Besides, excessive Cu nanoparticles in the binary catalyst were found rather harmful to the catalysis instead. However, the SAA catalyst Pt₁Cu@SAPO-11 showed a poor activity in hydroisomerization compared to Pt₁@CS, indicating that the alloy structure should go against the activation of reactant. The roles of Pt atoms and Cu nanoparticles in different catalysts were discussed in detail. The reaction mechanism of hydroisomerization was refined with the different functions of the dual metal sites. This work might be instructive for the design of single atom catalysts combined with metal nanoparticles.