No abstract

No abstract

NO 2 and dimethylether (DME) adsorption as well as DME and NO 2 co-adsorption on a transition metal-free g-alumina catalyst were investigated via in-situ transmission Fourier transform infrared spectroscopy (in-situ FTIR), residual gas analysis (RGA) and temperature programmed desorption (TPD) techniques. NO 2 adsorption at room temperature leads to the formation of surface nitrates and nitrites. DME adsorption on the alumina surface at 300 K leads to molecularly adsorbed DME, molecularly adsorbed methanol and surface methoxides. Upon heating the DME-exposed alumina to 500-600 K the surface is dominated by methoxide groups. At higher temperatures methoxide groups are converted into formates. At T > 510 K, formate decomposition takes place to form H 2 O(g) and CO(g). DME and NO 2 co-adsorption at 423 K does not indicate a significant reaction between DME and NO 2 . However, in similar experiments at 573 K, fast reaction occurs and the methoxides present at 573 K before the NO 2 adsorption are converted into formates, simultaneously with the formation of isocyanates. Under these conditions, NCO can further be hydrolyzed into isocyanic acid or ammonia with the help of water which is generated during the formate formation, decomposition and/or NCO formation steps. #

No abstract

No abstract