Amine-functionalized MIL-53(Al) with embedded ruthenium nanoparticles as a highly efficient catalyst for the hydrolytic dehydrogenation of ammonia borane

Abstract

Well-dispersed ruthenium nanoparticles (Ru NPs) are immobilized within the pores of amine-functionalized MIL-53 via an in situ impregnation-reduction method. The resulting Ru/MIL-53(Al)-NH 2 catalyst exhibits superior catalytic performance for the dehydrogenation of ammonia borane (AB) at ambient temperature relative to the Ru/MIL-53(Al) catalyst; it has a turnover frequency (TOF) of 287 mol H 2 min À1 (mol Ru) À1and an activation energy (E a ) of 30.5 kJ mol À1 . The amine groups present in the MIL-53(Al)-NH 2 framework facilitate the formation and stabilization of ultra-small Ru NPs by preventing their aggregation. Additionally, the Ru/MIL-53(Al)-NH 2 catalyst exhibits satisfactory durability and reusability:72.4% and 86.3% of the initial catalytic activity was maintained after the fifth successive cycle of the hydrolytic dehydrogenation of AB in the two respective tests.

The Hydrogen‐Storage Challenge: Nanoparticles for Metal‐Catalyzed Ammonia Borane Dehydrogenation

“…The same range of activity was achieved from MOF supported ruthenium catalysts Ru/MIL-53(Al)-NH 2 (Ru 18.10 wt%), which exhibited a TOF = 287 min -1 in hydrolytic AB dehydrogenation. 123,64 The MOF was believed to insure the formation and stabilization of ultra-small Ru NPs by preventing their aggregation (with a mean diameter of 1.2 and a size distribution ranging from 0.3 nm to 2.4 nm). The Ru/MIL-53(Al)-NH 2 retained ca 80% of its initial catalytic activity in fifth successive cycles of the hydrolytic dehydrogenation of AB.…”

“…274 heterogeneous catalysts for AB hydrolysis. This transition from ultra-small nanoparticles to nearly atomically dispersed, 43,100,123,145,155,252 down to single-atom catalysts (SACs) is thus a challenge for the future of such hydrogen production reactions which already started to be addressed.…”

“…These catalytic performances were attributed to the nearly atomically dispersed Co and Ni atoms, which interestingly opens to the question of cooperative two-single-atom heterogeneous catalysts for AB hydrolysis. This transition from ultra-small nanoparticles to nearly atomically dispersed, [43,100,123,145,155,251] down to single-atom catalysts (SACs) is thus a challenge for the future of such hydrogen production reactions which already started to be addressed.…”

Nanopore‐Supported Metal Nanocatalysts for Efficient Hydrogen Generation from Liquid‐Phase Chemical Hydrogen Storage Materials

“…After that, the double solvents method and/or overwhelming reduction approach were widely employed for the synthesis of MOF-supported metal nanocatalysts, [97][98][99]105,107,115] and the MIL-101 was used as a popular support and widely applied to immobilizing small metal NPs for AB solvolysis reactions. [94][95][96][97][98][99][100][101][102][103][105][106][107][108][109][110]183] Apart from the MIL-101, other types of MOFs, such as ZIF-8, [13b,c,111,112] UIO-66, [113][114][115]184] MIL-96, [119,120] MIL-53, [116][117][118] MIL-125, [121] and ZIF-67, [122] were also employed as supports to immobilize small metal NPs for the H 2 generation from AB solvolysis reactions. In general, the AB solvolysis reactions were catalyzed by noble metal catalysts, such as Pt, Rh, and Ru and these catalysts exhibited an excellent H 2 generation rate with high TOF values of above 100 min −1 .…”

Hydrolytic Dehydrogenation of Ammonia Borane Attained by Ru-Based Catalysts: An Auspicious Option to Produce Hydrogen from a Solid Hydrogen Carrier Molecule

“…They have been shown to be suitable to embed metal NPs as well as to stabilize them by incorporating additional functionalization. This was the case of Chen et al, who achieved well-dispersed Ru NPs immobilized within the pores of amine-functionalized MIL-53 by using an in-situ impregnation-reduction method [94]. It was claimed that the amino groups were located at the acid linkers in MIL-53(Al)-NH 2 , and served as Lewis bases, thus stabilizing the Ru precursor (i.e., RuCl 3 ) during the impregnation step.…”