USTC develops high-entropy-alloy catalyst to boost propane dehydrogenation efficiency

Recently, a research team from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences has developed a Pt-based high-entropy-alloy (HEA) catalyst that significantly enhances the efficiency of propane dehydrogenation (PDH), a critical process for producing propylene, a major chemical building block. The study was published in Angewandte Chemie International Edition.

Propane dehydrogenation is an essential route for propylene production, which is a key feedstock in the chemical industry. However, the process requires high temperatures that often lead to catalyst deactivation due to sintering and coke formation. Traditional Pt-based catalysts, while effective, can promote side reactions, reducing selectivity and stability. The quest for a catalyst that can withstand these harsh conditions and maintain high performance has been a significant challenge in the field.

Therefore, high-entropy alloys (HEAs), composed of five or more principal metals in a solid solution, have emerged as a potential solution due to their broad compositional space and adaptable electronic states. However, the exploration of HEA catalysts has been dominated by time-consuming and labor-intensive trial-and-error approaches, highlighting the need for a more rational design strategy.

To address the time-consuming challenge, the research team employed a fast-moving tube furnace for catalyst preparation to synthesize HEA nanoparticles with a uniform and stable structure. Metal precursors were loaded onto a fumed silica support and then rapidly reduced in the preheated furnace. This fast process, completed within 1 second, bypassed the temperature-rising stage and enabled the simultaneous decomposition and reduction of all precursors, effectively avoiding potential phase separation.

Moreover, to improve traditional trial-and-error methods, the research team embarked on a progressive approach to design and fabricate HEA catalysts guided by alloying effects. They selected Cu, Sn, Au, and Pd to induce specific effects on Pt, such as dilution, encapsulation, surface enrichment, and inhomogeneity, respectively. This strategic selection and combination of metals allowed them to manipulate the geometric and electronic properties of the catalyst, thereby enhancing its performance in PDH.

By leveraging and balancing these alloying effects, the research team successfully fabricated the PtCuSnAuPd/SiO₂ HEA catalyst. This catalyst demonstrated outstanding catalytic performance in PDH. At a weight hourly space velocity (WHSV) of 354 h⁻¹, it achieved propylene formation rates of 256 and 390 mol C₃H₆ gₚₜ⁻¹ h⁻¹ at 550 °C and 600 °C, respectively, significantly outperforming many other reported multimetallic alloys. The catalyst also exhibited high selectivity for propylene, with selectivity remaining above 97% in a 220-hour long-term stability test.

The novel catalyst offers a combination of high activity, selectivity, and stability, which could have a significant impact on the production of propylene in the chemical industry. The rational design strategy based on understanding alloying effects provides a new approach for the development of advanced catalysts for other reactions as well.