Solve catalytic puzzles with mathematical thinking! The “degree of isolation” descriptor design unit point alloy catalyst

On March 27, 2023, Professor Gong Jinlong’s research team of Tianjin University published the research results entitled “Designing single-site alloy catalysts using a degree-of-isolation descriptor” in the journal Nature Nanotechnology.

Starting from theoretical calculations, this study comprehensively considers the electronic and geometric regulation of alloys, successfully quantifies the repulsion between the active site and the adsorbate in both electronic and geometric aspects, and constructs the microenvironmental descriptor “degree-of-isolation”. The “degree of isolation” can directly predict the selectivity of propylene in propane dehydrogenation, which provides a good demonstration for the rational design of catalysts.

The corresponding author of the paper is Professor Gong Jinlong, and the first authors are Professor Chang Xin and Professor Zhao Zhijian.

Propylene is an important chemical raw material, not only has diversified production processes, but also has a rich downstream industrial chain, and plays a huge role in industrial production. Propane dehydrogenation (PDH) is currently one of the most promising propylene production technologies and has attracted widespread attention in recent years. However, China’s existing PDH process mainly relies on high-priced imported mature process packages, and the catalyst as the core of the process is firmly controlled by developed countries. Although a large number of propane dehydrogenation catalysts have been developed in current research, their performance still needs to be improved. Compared with the traditional experimental trial and error method, the computational condensation of predictive descriptors through density functional theory (DFT) can accelerate the design process of catalysts. However, how to reasonably interpret the microenvironment of the catalytic site in the alloy and extract the direct relationship between the descriptor and the catalytic performance is still a great challenge.

Professor Gong Jinlong’s team of Tianjin University proposed a research strategy of “catalytic microenvironment prediction of catalytic performance”. At the heart of this approach is the quantitative interpretation of the catalytic microenvironment, which is clearly correlated with changes in catalytic performance. Considering that the catalytic environment is affected by geometry and electronic structure, this study specifically adopts the idea of “decoupling the two and quantifying them separately”, and couples the quantitative description of the two in a simple mathematical form with “repulsion of adsorbate and active site” as the link, so as to condense the “isolation” of the micro-environment descriptor. By simply entering the electronic and geometric parameters of the catalyst, the value of “isolation” can be calculated, which directly predicts the olefin selectivity and accelerates the selection of catalytic materials with excellent performance. In theoretical calculations and experiments, both “isolation” and propylene selectivity show a “volcanic type” relationship, revealing the Sabatier principle of unit point alloy catalyst design. This shows that the repulsion of the site to the adsorbate should not be too strong or too weak, and the catalyst with moderate “isolation” will show the best catalytic performance.

Figure 1: Electronic regulation of the active site

Figure 2: Geometric regulation of the active site

Figure 3: “Isolation” vs. “volcanic type” of propylene selectivity

Figure 4: Experimental validation

This work emphasizes the importance of describing and regulating the catalytic microenvironment, which is of great significance for promoting the transition of catalysts from experimental trial and error to rational design. (Source: Science Network)

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