Key Lab of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.
Key Lab of Applied Chemistry of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou 310028, China.
J Am Chem Soc. 2020 Sep 23;142(38):16429-16436. doi: 10.1021/jacs.0c07792. Epub 2020 Sep 11.
Nonoxidative dehydrogenation is promising for production of light olefins from shale gas, but current technology relies on precious Pt or toxic Cr catalysts and suffers from thermodynamically oriented coke formation. To solve these issues, the earth-abundant iron catalyst is employed, where Fe species are effectively modulated by siliceous zeolite, which is realized by the synthesis of Fe-containing MFI siliceous zeolite in the presence of ethylenediaminetetraacetic sodium (FeS-1-EDTA). Catalytic tests in ethane dehydrogenation show that this catalyst has a superior coke resistance in a 200 h run without any deactivation with extremely high activity and selectivity (e.g., 26.3% conversion and over 97.5% selectivity to ethene in at 873 K, close to the thermodynamic equilibrium limitation). Multiple characterizations demonstrate that the catalyst has uniformly and stably isolated Fe sites, which improves ethane dehydrogenation to facilitate the fast desorption of hydrogen and olefin products in the zeolite micropores and hinders the coke formation, as also identified by density functional calculations.
非氧化脱氢是从页岩气中生产轻烯烃的一种很有前途的方法，但目前的技术依赖于贵金属 Pt 或有毒的 Cr 催化剂，并且存在受热力学控制的积碳问题。为了解决这些问题，采用了丰富的铁催化剂，其中硅沸石有效地调节了铁物种，这是通过在乙二胺四乙酸钠（FeS-1-EDTA）存在下合成含铁 MFI 硅沸石来实现的。在乙烷脱氢反应的催化测试中，该催化剂在 200 小时的运行中具有出色的抗积碳能力，没有任何失活现象，并且具有极高的活性和选择性（例如，在 873 K 时转化率为 26.3%，乙烯选择性超过 97.5%，接近热力学平衡限制）。多种表征表明，该催化剂具有均匀且稳定的孤立铁位，这促进了乙烷脱氢反应，有利于沸石微孔中氢气和烯烃产物的快速脱附，并阻碍了积碳的形成，这也通过密度泛函计算得到了证实。
