Combined “Gateway” and “Spillover” effects originated from a CeNi_(5) alloy catalyst for hydrogen storage of MgH_(2)

Efficient catalysts enable MgH2 with superior hydrogen storage performance.Herein,we successfully synthesized a catalyst composed of Ce and Ni (i.e.CeNi_(5) alloy) with splendid catalytic action for boosting the hydrogen storage property of magnesium hydride (MgH_(2))The MgH2–5wt%CeNi_(5) composite’s initial hydrogen release temperature was reduced to 174℃ and approximately 6.4wt%H_(2) was released at 275℃ within 10 min.Besides,the dehydrogenation enthalpy of MgH_(2) was slightly decreased by adding CeNi_(5).For hydrogenation,the fully dehydrogenated sample absorbed 4.8wt%H_(2) at a low temperature of 175℃.The hydrogenation apparent activation energy was decreased from(73.60±1.79) to (46.12±7.33) kJ/mol.Microstructure analysis revealed that Mg_(2)Ni/Mg_(2)NiH_(4) and CeH_(2.73) were formed during the process of hydrogen absorption and desorption,exerted combined“Gateway”and“Spillover”effects to reduce the operating temperature and improve the hydrogen storage kinetics of MgH_(2).Our work provides an example of merging“Gateway”and“Spillover”effects in one catalyst and may shed light on designing novel highly-effective catalysts for MgH_(2) in near future.

FeCoNiCrMo high entropy alloy nanosheets catalyzed magnesium hydride for solid-state hydrogen storage

The catalytic effect of FeCoNiCrMo high entropy alloy nanosheets on the hydrogen storage performance of magnesium hydride(MgH_(2))was investigated for the first time in this paper.Experimental results demonstrated that 9wt%FeCoNiCrMo doped MgH_(2)started to dehydrogenate at 200℃and discharged up to 5.89wt%hydrogen within 60 min at 325℃.The fully dehydrogenated composite could absorb3.23wt%hydrogen in 50 min at a temperature as low as 100℃.The calculated de/hydrogenation activation energy values decreased by44.21%/55.22%compared with MgH_(2),respectively.Moreover,the composite’s hydrogen capacity dropped only 0.28wt%after 20 cycles,demonstrating remarkable cycling stability.The microstructure analysis verified that the five elements,Fe,Co,Ni,Cr,and Mo,remained stable in the form of high entropy alloy during the cycling process,and synergistically serving as a catalytic union to boost the de/hydrogenation reactions of MgH_(2).Besides,the FeCoNiCrMo nanosheets had close contact with MgH_(2),providing numerous non-homogeneous activation sites and diffusion channels for the rapid transfer of hydrogen,thus obtaining a superior catalytic effect.

Boosting low-temperature selective catalytic reduction of NO_(x)with NH_(3)of V_(2)O_(5)/TiO_(2)catalyst via B-doping

A series of B-doped V_(2)O_(5)/TiO_(2) catalysts has been prepared the by sol-gel and impregnation methods to investigate the influence of B-doping on the selective catalytic reduction(SCR)of NOxwith NH_(3).X-ray diffraction,Brunauer-Emmett-Teller specific surface area,scanning electron microscope,X-ray photoelectron spectroscopy,temperature-programmed reduction of H_(2) and temperature-programmed desorption of NH_(3)technology were used to study the effect of the B-doping on the structure and NH_(3)-SCR activity of V_(2)O_(5)/TiO_(2) catalysts.The experimental results demonstrated that the introduction of B not only improved the low-temperature SCR activity of the catalysts,but also broadened the activity temperature window.The best SCR activity in the entire test temperature range is obtained for VTiB_(2.0) with 2.0%doping amount of B and the NO_(x) conversion rate is up to 94.3%at 210℃.The crystal phase,specific surface area,valence state reducibility and surface acidity of the active components for the as-prepared catalysts are significantly affected by the B-doping,resulting in an improved NH_(3)-SCR performance.These results suggest that the V_(2)O_(5)/TiO_(2) catalysts with an appropriate B content afford good candidates for SCR in the low temperature window.