Plasma-Induced Chemisorption of Nitrogen and Its Chemical Reactivity on Alumina

Abstract

Nitrogen was chemisorbed on an alumina ( Al2O3) surface by plasma discharge of N2, and the chemical behavior of chemisorbed nitrogen was studied by temperature-programmed desorption (TPD) and infrared (IR) spectroscopy. Molecular nitrogen N2(ad) chemisorbed on an Al2O3 surface showed a high reactivity with hydrogen even at room temperature, if Pt is present on the Al2O3 surface. Hydrogenated species, NH x (ad) (x=1 or 2) and NH3(ad), were formed on the Al2O3 surface, as evidenced by IR spectroscopy. It is suggested that hydrogen spill-over from the Pt surface onto the Al2O3 catalyst plays an important role in the mechanism of hydrogenation reaction.

Catalytic Effects of Metal-loaded Membrane-like Alumina Tubes on Ammonia Synthesis in Atmospheric Pressure Plasma by Dielectric Barrier Discharge

“…When plasma was generated through MA in N 2 for 2 h, two small absorption bands appeared approximately at 2238 and 2210 cm -1 in Spectrum a3. These are assigned to N-N stretching modes of molecular N 2 (a) chemisorbed on different sites of MA with an end-on configuration according to Kameoka et al [16][17][18] who observed two peaks at about 2260 and 2230 cm -1 in the IR spectrum of Al 2 O 3 exposed to plasma-excited N 2 . The smaller Similar IR peaks due to N 2 (a) species were also detected in Spectrum b3 for Ru/MA, but they were approximately 7 times as intense as those for MA, implying the presence of other adsorption sites.…”

“…Kameoka et al [16][17][18] observed IR bands approximately at 2260 and 2230 cm -1 after a N 2 -plasma treatment of Al 2 O 3 and assigned them to the N-N stretching of N 2 (a) molecules strongly chemisorbed on the Al 2 O 3 surface with an end-on configuration. They also found that when Pt was present on Al 2 O 3 , the N 2 (a) molecules reacted with H 2 at room temperature to form NH x (x = 1-3) species.…”

Tubular membrane-like catalyst for reactor with dielectric-barrier-discharge plasma and its performance in ammonia synthesis

“…An interaction of nitrogen plasma with alumina has been studied by Kunimori et al [32], who found from IR and TPD measurements that N 2 molecules were strongly chemisorbed on the Al 2 O 3 surface without dissociation by the plasma excitation. It was also confirmed that the molecular N 2 (ad) was hydrogenated to NH x (ad) (x = 1-3) species by hydrogen exposure at room temperature when platinum was present on Al 2 O 3 .…”

Inelastic Neutron Scattering Observation of Plasma-Promoted Nitrogen Reduction Intermediates on Ni/γ-Al2O3

“…Nonthermal plasmas can activate nitrogen (e.g., vibrationally, electronically, or via dissociation pathways) to facilitate adsorption on the catalyst surface as shown in Scheme a . It should be noted that the plasma is fairly indiscriminate in its ability to promote adsorption, and thus it is likely that both the metal surface and the alumina support uptake nitrogen. , Following nitrogen adsorption, hydrogen can be introduced either as a plasma or thermally to hydrogenate the surface bound N species. In the case of thermal hydrogenation (Scheme b), hydrogen can only dissociatively adsorb on the metal surface before hydrogenating surface nitrogen.…”