Acid-durable electride with layered ruthenium for ammonia synthesis: boosting the activity via selective etching. Issue 22 (9th May 2019)

• Record Type: Journal Article
• Authors: Li, Jiang; Wu, Jiazhen; Wang, Haiyun; Lu, Yangfan; Ye, Tiannan; Sasase, Masato; Wu, Xiaojun; Kitano, Masaaki; Inoshita, Takeshi; Hosono, Hideo
• Is Part Of: Chemical science. Volume 10:Issue 22(2019)
• Page Start: 5712
• Page End: 5718
• Publication Date: 2019-05-09
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c9sc01539f
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : We reported LnRuSi as a B5 -site-free Ru catalyst for ammonia synthesis, and its activity enhanced 2–4-fold by selective etching with EDTA-2Na. Abstract : Ruthenium (Ru) loaded catalysts are of significant interest for ammonia synthesis under mild reaction conditions. The B5 sites have been reported as the active sites for ammonia formation, i.e., Ru with other coordinations were inactive, which has limited the utilization efficiency of Ru metal. The implantation of Ru into intermetallic compounds is considered to be a promising approach to tune the catalytic activity and utilization efficiency of Ru. Here we report an acid-durable electride, LnRuSi (Ln = La, Ce, Pr and Nd), as a B5 -site-free Ru catalyst. The active Ru plane with a negative charge is selectively exposed by chemical etching using disodium dihydrogen ethylenediaminetetraacetate (EDTA-2Na) acid, which leads to 2–4-fold enhancement in the ammonia formation rate compared with that of the original catalyst. The turnover frequency (TOF) of LnRuSi is estimated to be approximately 0.06 s −1, which is 600 times higher than that of pure Ru powder. Density functional theory (DFT) calculations revealed that the dissociation of N2 occurs easily on the exposed Ru plane of LaRuSi. This systematic study provides firm evidence that layered Ru with a negative charge in LnRuSi is a new type of active site that differs significantly from B5 sites.