Hydrotalcite framework stabilized ruthenium nanoparticles (Ru/HTaL): efficient heterogeneous catalyst for the methanolysis of ammonia-borane

İsmail Burak Bağuç,Ahmet Bulut,Mehmet Yurderi̇,Gülşah Saydan Kanberoğlu

doi:10.3906/kim-1910-44

İsmail Burak Bağuç, Ahmet Bulut + Show 2 more

Open Access

https://doi.org/10.3906/kim-1910-44

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Abstract

Ruthenium nanoparticles stabilized by a hydrotalcite framework (Ru/HTaL) were prepared by following a 2-step procedure comprising a wet-impregnation of ruthenium(III) chloride precatalyst on the surface of HTaL followed by an ammonia-borane (NH3BH3) reduction of precatalyst on the HTaL surface all at room temperature. The characterization of Ru/HTaL was done by using various spectroscopic and visualization methods including ICP-OES, P-XRD, FTIR, 11B NMR, XPS, BFTEM, and HRTEM. The sum of the results gained from these analyses has revealed the formation of well-dispersed and highly crystalline ruthenium nanoparticles with a mean diameter of 1.27 ±0.8 nm on HTaL surface. The catalytic performance of Ru/HTaL in terms of activity, selectivity, and stability was investigated in the methanolysis of ammonia-borane (NH3BH3 , AB), which has been considered as one of the most promising chemical hydrogen storage materials. It was found that Ru/HTaL can catalyse methanolysis of AB effectively with an initial turnover frequency (TOF) value of 392.77 min-1 at conversion (>95%) even at room temperature. Moreover, the catalytic stability tests of Ru/HTaL in AB methanolysis showed that Ru/HTaL acts as a highly stable and reusable heterogeneous catalyst in this reaction by preserving more than 95% of its initial activity even at the 5th recycle.

Highlights

One of the most critical obstacles in ‘hydrogen economy’ is the safe and efficient storage and release of hydrogen under mild conditions [1,2]
To determine the amount of ruthenium loading in the Ruthenium nanoparticles stabilized by a hydrotalcite framework (Ru/HTaL) sample, inductively coupled plasma optical emission spectroscopy (ICP-OES) analyses were carried out, which showed that the Ru/HTaL sample prepared with our protocol contains 1.12 wt% ruthenium
The comparison of these 2 powder X-ray diffraction (P-XRD) patterns clearly shows that the crystallinity of the host material (HTaL) was retained at the end of the synthesis protocol as the definite Bragg peaks of HTaL are seen in the P-XRD pattern of the Ru/HTaL material

Summary

Introduction

One of the most critical obstacles in ‘hydrogen economy’ is the safe and efficient storage and release of hydrogen under mild conditions [1,2]. At this concern, the recent studies performed in this field have revealed that ammonia-borane (NH 3 BH 3 , AB) needs serious consideration as one of the most promising solid materials in chemical hydrogen storage owing to its high hydrogen content (19.6 wt%), stability, and nontoxicity [3,4,5]. Various catalytic systems such as polymer stabilized-nickel(0) [17], Ru/MMT [18], PVP-stabilized Ru(0) [19], Co 48 Pd 52 /C [20], Cu-Cu 2 OCuO/C [21], mesoporous CuO [22], Rh(0)/nano-SiO 2 [23], and copper nanoparticles [24] have been designed and tested in this important catalytic transformation, but the development of highly active and stable catalytic material is still one of the most important goals for this important catalytic transformation.

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