Professors Wang Ye and Fu Gang from the State Key Laboratory of Physical Chemistry of Solid Surfaces at Xiamen University, together with Professor Jiang Zheng from the University of Science and Technology of China, have developed an ultra-high stability In/Rh@S-1 catalyst with a lifespan exceeding 5500 hours. This catalyst can highly selectively catalyze the direct dehydrogenation of low-carbon alkanes such as propane to produce corresponding olefins under near thermodynamic equilibrium yield conditions. On March 1st, their groundbreaking research was published in the journal Science.
Major Breakthrough: Construction of High-Stability Rh Single-Atom Alkane Dehydrogenation Catalysts through In Situ Dynamic Migration. Provided by the research team.
Low-carbon olefins are essential raw materials for synthesizing fibers, rubbers, plastics, and many other bulk chemical products, with a global annual demand exceeding 300 million tons. Direct dehydrogenation of alkanes is a significant industrial route to produce olefins, currently dominated by Western companies. Due to the harsh high-temperature conditions required for the reaction, commercial alkane dehydrogenation catalysts still face challenges such as easy sintering, carbon build-up, frequent need for catalyst regeneration, along with associated high energy consumption and emissions.
Constructing metal catalysts that are stable under harsh high-temperature conditions, while also being highly active and selective, is a recognized major challenge in the field of catalysis. Although significant progress has been made in enhancing the stability of propane dehydrogenation catalysts both domestically and internationally in recent years, the performance degradation due to metal migration at high temperatures has made it difficult to achieve continuous stable operation for more than 500 hours under near-industrial conditions. The team led by Professor Wang Ye at our school has taken a novel approach, proposing the concept of "in situ dynamic construction of active sites." Leveraging the oxygen affinity and dynamic migration characteristics of In, they designed an In/Rh@S-1 catalyst with dynamically formed and highly stable active sites under reaction conditions. In this catalyst, single-atom Rh is located inside the pores of S-1 (Silicalite-1) zeolite, while In species, which spontaneously migrate into the pores and interact with the zeolite's silanol groups, stabilize the Rh single atoms through In-Rh bonds, forming a zeolite-confined RhInx active center that is anchored to the zeolite framework via In-O bonds. This method offers a new approach to the design and synthesis of ultra-stable, efficient single-atom catalysts.
The significant breakthrough of this work is that the novel In/Rh@S-1 catalyst effectively avoids carbon build-up without the need for adding hydrogen to suppress carbon formation like in commercial alkane dehydrogenation processes, nor does it require frequent regeneration through air burning, making the process simpler and greener. Using pure propane as the feedstock, this catalyst maintained stable activity and selectivity for up to 5500 hours of continuous testing under near-industrial reaction conditions at 550 oC. At a high propane conversion rate (>60%) at 600 oC, the In/Rh@S-1 catalyst could operate continuously and stably for more than 1200 hours. Additionally, the single-atom Rh exhibited exceptional C-H bond activation performance, with a propylene production rate per unit of precious metal mass that is one to two orders of magnitude higher than current Pt-based catalysts. This work paves the way for a new system of alkane dehydrogenation catalysts that do not require frequent regeneration beyond Pt and Cr-based systems, promising the development of clean production technologies with independent intellectual property rights and contributing to the goal of carbon neutrality.
Related paper information: https://www.science.org/doi/10.1126/science.adk5195
