Transition metal nanoparticles supported La-promoted MgO as catalysts for hydrogen production via catalytic decomposition of ammonia

The uniformly dispersed transition metal(Co, Ni and Fe) nanoparticles supported on the surface of La-promoted Mg O were prepared via a deposition-precipitation method for hydrogen production from catalytic decomposition of ammonia. X-ray diffraction, N2 adsorption-desorption, transmission electron microscopy, temperature-programmed reduction and temperature-programmed desorption were used to investigate the structure-activity relation of catalysts in NH3 decomposition. The results show that the strong interaction between active species and support can effectively prevent the active species from agglomerating during ammonia decomposition reaction. In addition, the introduction of La species not only facilitates the adsorption and decomposition of NH3 and desorption of N2, but also benefits the better dispersion of the active species. The prepared catalysts showed very high catalytic activity for ammonia decomposition compared with the same active composition samples that reported previously. Meanwhile, the catalysts showed excellent high-temperature stability and no any deactivation was observed, which are very promising candidates for the decomposition of ammonia to hydrogen.

Hydrogen production via catalytic decomposition of NH3 using promoted MgO-supported ruthenium catalysts

Catalytic decomposition of NH3 to high purity hydrogen offers a promising strategy for fuel cells,but presents challenges for high hydrogen yields at comparatively low temperatures due to the lack of efficient catalysts.Here,we report the facile preparation of ultra-fine ruthenium(Ru)species dispersed on MgO,which show excellent activity and high temperature stability for NH3 decomposition reaction.The hydrogen yield of the prepared Ru/MgO catalysts reaches ca.2,092 mmol H2 gRu^-1 min^-1 at 450℃,far exceeding that of the previously reported most reactive Ru・based catalysts and the same chemical composition samples prepared by other approaches.Various characterization techniques containing X-ray absorption fine structure(XAFS),in-situ diffuse reflectance infrared Fourier transform spectroscopy(in-situ DRTFTS)and temperature-programmed reduction/desorption(TPR/TPD)were carried out to explore the structure-function relation of the prepared Ru/MgO catalysts.We found that the Ru species interact strongly with the MgO support,which can efficiently protect the Ru species and MgO support from agglomerating during NH3 decomposition test,maintaining the stability of the catalysts.