Metal–support interactions on Ru/CaAlO_x catalysts derived from structural reconstruction of Ca–Al layered double hydroxides for ammonia decomposition

Abstract

Strong metal–support interaction (SMSI) over Ru/CaAlOx was constructed by utilizing the surface structural reconstruction of Ca–Al layered double hydroxides (LDHs) in aqueous solution and their subsequent hydroxide-to-oxide transformations.

Review of the Decomposition of Ammonia to Generate Hydrogen

“…The Ru supported on a layered oxide composed of Ca and Al (CaAlO x ) was compared with other types of supports widely used in the literature, carbon nanotubes and SiO 2 , obtaining a higher conversion (78 vs 21 and 62% at 450 °C, respectively). 212 In a similar way, Hayashi et al 213 4 showed the highest conversion. Barium has also shown to be a catalyst promoter when used to modify an alumina support.…”

“…Comparing catalysts based on Ru promoted with K supported on different materials (CNTs, MgO, sepiolite, and CaO), Sayas et al obtained the highest catalytic activity with CaO, which is the most basic support of those used. The Ru supported on a layered oxide composed of Ca and Al (CaAlO x ) was compared with other types of supports widely used in the literature, carbon nanotubes and SiO 2 , obtaining a higher conversion (78 vs 21 and 62% at 450 °C, respectively) . In a similar way, Hayashi et al tested as supports an electride, [Ca 24 Al 28 O 64 ] 4+ (e – ) 4 , where electrons work as anions, and mayenite oxide [Ca 24 Al 28 O 64 ] 4+ (O 2– ) 2 , and compared the results with conventional catalysts of Ru supported on CaO, Al 2 O 3 , MgO.…”

Strong Metal–Support Interaction for 2D Materials: Application in Noble Metal/TiB2 Heterointerfaces and their Enhanced Catalytic Performance for Formic Acid Dehydrogenation

“…This overlayer serves as a continuous physical barrier hindering the sintering of metal nanoparticles. Besides the well‐known occurrences at metal/reducible oxide interfaces, recent studies have also reported SMSI on nonoxidic supports, such as hydroxyapatite, [ 8 ] boron nitride, [ 9 ] layered double hydroxides, [ 10 ] and carbides. [ 11 ] These new discoveries motivate the exploration of SMSI beyond the classical metal/oxide catalyst structure.…”

Ru-Based Catalysts for Ammonia Decomposition: A Mini-Review

“…Hence, good catalytic activity in the mid-to low-temperature region at high GHSV was reported (Table 4) for Ru/MgO catalysts. 35,59,71,72 Fujitani et al 71 found that the interaction between Ru and MgO was highly dependent on the methods of catalyst preparation. As depicted in Figure 7, NH 3 conversions at 673 K over the Ru/MgO catalysts prepared by coprecipitation (CPT) and deposition precipitation (DP) were almost 3 times that over the Ru/MgO prepared by the incipient wetness impregnation (IWI) method.…”

“…The use of metal amides and imides for ammonia decomposition has also been reviewed by Gao et al and Mukherjee et al, and the metal amides and imides work as N carriers for chemical looping ammonia decomposition. As one of the most promising candidates for ammonia decomposition, Ru-based catalysts have been widely researched in the past decade. ,− Many novel synthesis techniques have been employed for fabricating Ru catalysts, and some new materials have been applied for supporting Ru; moreover, advanced characterization techniques and theoretical methods have been employed to study the structure–activity relationship and reaction mechanism.…”