Propylene oxide (PO) is a valuable chemical intermediate, and the direct epoxidation of propylene with H2 and O2 has gained interest as a green and efficient method of production. However, the current catalyst used in this process, Au, is expensive and in limited supply. As a result, there is a need for highly-active non-noble catalysts for propylene epoxidation. In response to this challenge, a research team led by Prof. Chen Xinqing from the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences has proposed the use of non-noble nickel catalysts supported on titanium silicate-1 (TS-1) zeolite.
The researchers synthesized a series of non-noble Ni/TS-1 catalysts using the deposition precipitation method. They observed that the strong interaction between the nickel nanoparticles and TS-1 was the key to their excellent catalytic performance in the gas-phase epoxidation of propylene. Among the catalysts prepared, the 2% Ni/TS-1 catalyst stood out with a high PO selectivity of 76.8% and a PO production rate of 151.9 g PO/(h·Kgcat). Furthermore, this catalyst exhibited long-term stability at 200 °C, exceeding 20 hours.
To gain a deeper understanding of the catalyst’s performance, the researchers conducted various characterizations and utilized in-situ technologies. Through these investigations, they discovered that metallic nickel played a crucial role in promoting the reaction between hydrogen and oxygen, leading to the in-situ synthesis of H2O2. This H2O2 then oxidized propylene to produce PO. Theoretical calculations also provided insights into the passivation layer on the nickel surface, which facilitated the production of H2O2.
The development of non-noble nickel catalysts supported on TS-1 zeolite for propylene epoxidation is a significant step towards a more sustainable and cost-effective process. By reducing reliance on expensive and limited noble metals like gold, the researchers have opened up new possibilities for large-scale production of propylene oxide. This discovery not only contributes to the field of catalysis but also aligns with the goal of creating greener and more efficient chemical processes.
Moving forward, further research can be conducted to optimize the performance of the non-noble Ni/TS-1 catalyst. By exploring different synthesis methods and catalyst compositions, it may be possible to enhance catalytic activity, selectivity, and stability even further. Additionally, understanding the reaction mechanism at a molecular level could provide valuable insights for the design of novel catalysts for other chemical transformations.
The research led by Prof. Chen Xinqing and his team has demonstrated the potential of non-noble nickel catalysts supported on TS-1 zeolite for propylene epoxidation. This breakthrough offers a more sustainable and economically viable solution for the production of propylene oxide. As the field of catalysis continues to evolve, it is exciting to see how these advancements will shape the future of chemical manufacturing.