High Recyclability Magnetic Iron Oxide‐Supported Ruthenium Nanocatalyst for H₂ Release from Ammonia‐Borane Solvolysis

Abstract

We report the high capacity of recycling of a technologically simple, easily recoverable, Ru@Fe3O4 magnetic nanocatalyst, efficient in the release of H2 from ammonia-borane (AB) solvolysis, using H2O or methanol at room temperature (25 °C). The initially oxidized Ru small nanoparticles (2-4 nm) are well-dispersed on an iron oxide support (i. e. super paramagnetic iron oxide of spinel structure, SPIO, as aggregates of 20 nm to a few m). As nanocatalyst, this composite achieved short-time (<10 min) AB full hydrolysis (3 equiv H2, no NH3, [AB] = 0.1 mol L -1 ) with a turnover frequency (TOF) of ca 20 min -1 (86 min -1 at 50°C). The post-catalysis characterization of the composite showed the formation of well-defined crystalline hcp Ru(0) dispersed on the SPIO. The activity for full H2 release from AB is conserved over ten cycles, which is among the most effective recycling processes reported to date (a magnetic recycling is achieved in <2 min). Pleasingly, an even superior activity was found in the more challenging AB methanolysis, with a TOF up to ca 30 min -1 for full H2 release, achieved in a recycling process repeated over 8 cycles.

Spontaneous Emulsification of Organometallic Complexes Applied to the Synthesis of Nanocapsules Active for H2 Release from Ammonia-Borane

“…The activity of the colloidal species toward hydrogen (H 2 ) release from the hydrolysis of ammonia-borane (NH 3 BH 3 , AB) is reported. , Transition metal-catalyzed hydrolysis of materials having a high gravimetric content of H 2 , like ammonia-borane (19 wt %), has been envisaged as a solid safe hydrogen storage (avoiding high-pressure gas or cold liquid storage) . While some dispersed colloids and many heterogeneous catalysts of the platinum group metals have been investigated, − the performances of nano-objects obtained from the reduction of such spontaneous emulsions remained to be tested.…”

Exposed Facet Tailoring of Ni/Cu Catalysts for Boosting Dehydrogenation of Ammonia Borane

“…Effective catalysts are required to lower the energy barriers of the dehydrogenation process and, thereby, render it more efficient . Despite the fact that precious metals such as Pt, Ru, Rh, and Pd are among the most active catalysts for AB hydrolysis, the high cost and low abundance of these compounds in the earth’s crust hinders their widespread application. As a result, there is an extreme urge to seek inexpensive catalysts with appreciable catalytic activity, thereby improving the performance of AB hydrolysis for hydrogen production .…”