Influence of the Rare Earth (R) Element in Ru‐supported RScSi Electride‐like Intermetallic Catalysts for Ammonia Synthesis at Low Pressure: Insight into NH3 Formation Mechanism. Issue 3 (9th January 2023)

• Record Type: Journal Article
• Authors: Croisé, Charlotte; Alabd, Khaled; Tencé, Sophie; Gaudin, Etienne; Villesuzanne, Antoine; Courtois, Xavier; Bion, Nicolas; Can, Fabien
• Is Part Of: ChemCatChem. Volume 15:Issue 3(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-01-09
• Subjects: intermetallic -- hydride -- NH3 -- ruthenium -- transient experiments; Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.202201172
• Languages: English
• ISSNs: 1867-3880

Abstract

Abstract: This study investigates the influence of the rare‐earth ( R ) element in Ru/ R ScSi electride‐like intermetallic catalysts for ammonia synthesis under mild conditions (300–450 °C; 1–5 bar). All materials present poor specific surface area and the grain size impacts the ammonia yield. The catalytic performances follow the La to Gd lanthanides series (Ru1.7 /LaScSi=Ru1.7 /CeScSi=Ru1.7 /PrScSi>Ru1.7 /NdScSi>Ru1.5 /SmScSi>Ru1.3 /GdScSi) and appear correlated with the formation of the hydride phase. Ru1.7 /CeScSi shows remarkable catalytic activity under moderate condition (0.58 mmolNH3 /h/g at 300 °C, 1 bar) associated with its reversible hydrogen storage–release properties. It is evidenced that R ScSi materials assist the N2 dissociation in agreement with their electride character and that the hydrogen for NH3 formation mainly comes from gaseous hydrogen and not primarily from the hydride phase. It is suggested that NHX formation could be the rate determining step rather than the N2 cleavage over these catalysts. Abstract : The activity in ammonia synthesis follows the La to Gd lanthanides series. Electride behaviors helps to N2 dissociation. Reversible hydrogen storage‐release properties impact NH3 production. Hydrogen in the formed NH3 mainly comes from gaseous hydrogen. Ru supported CeScSi electride shows remarkable activity at low temperature and pressure (300 °C, 1 bar).