麻豆淫院

Light alkanes are relatively simple molecules made entirely of carbon and hydrogen, arranged in linear or branching structures. Their oxidized counterparts, which include alcohols, epoxides, ketones, and aldehydes, are ubiquitous in the chemical industry, as they serve as essential starting materials in the synthesis of commodity substances, fine chemicals, agrochemicals, and pharmaceuticals. However, the selective oxidation of light alkanes remains a significant challenge.

To date, scientists have explored various types of catalysts for this task. Although some offer decent performance in gas-phase reactions, there are inherent advantages to developing catalysts applicable to liquid-phase selective oxidation. However, such catalysts often suffer from poor reusability, require extreme reaction conditions, or can only operate in the presence of heavy oxidants or photoirradiation.

Fortunately, a research team from the Institute of Science Tokyo, Japan, is on track to find a solution to these problems. Led by Professor Keigo Kamata, they have been investigating various iron-oxide-based perovskites as catalysts for years. In a recent study in ACS Applied Materials & Interfaces on November 1, 2024, the team successfully developed a promising catalyst that could revolutionize the selective oxidation of alkanes.

The researchers focused on the oxidation of isobutane, a simple four-carbon alkane, into tert-butyl alcohol as a representative reaction with multiple applications.

"In our preliminary examinations of the oxidation of isobutane, we found that high-valent iron-based perovskite oxides like BaFeO_3鈭捨� and SrFeO_3鈭捨�, on the one hand, and LaFeO₃, on the other, have drawbacks in terms of reusability and C鈭扝 bond activation," explains Kamata.

"In this work, we focused on the partial substitution of La鲁鈦� in LaFeO₃ with Sr虏鈦� to achieve both stability and reactivity simultaneously."

In this way, seeking to obtain the best of both worlds through a multi-element approach, the team synthesized La_1-xSr_xFeO_3鈭捨� nanoparticles of various compositions and tested them. Through a series of experiments, they observed that La_0.8Sr_0.2FeO_3鈭捨� was the composition with the best performance in terms of yield. With this catalyst, tert-butyl alcohol could be obtained as the main product with high selectivity under an oxygen atmosphere, with small quantities of byproducts.

Notably, this perovskite functioned properly under mild reaction conditions. Kamata remarks, "La_0.8Sr_0.2FeO_3鈭捨� efficiently catalyzed the oxidation of isobutane even at 60 掳C with good selectivity for tert-butyl alcohol. In contrast, high reaction temperatures of about 130 掳C, excess amounts of specific additives or oxidants, and high oxygen pressures of 3.5 MPa were typically required for previously reported homogeneously catalyzed systems."

These features, coupled with its outstanding stability and reusability, make La_0.8Sr_0.2FeO_3鈭捨� an important achievement in perovskite catalyst design.

The research team also conducted mechanistic studies to understand the origin of the material's notable properties. The insights obtained in this work will hopefully guide and inspire the development of solid perovskite catalysts made from earth-abundant elements. Ultimately, this could pave the way for more efficient and less costly synthesis of various useful chemicals, supporting worldwide sustainability goals.