The catalytic reduction of nitric oxide in automobile exhause gases--I. Tests of iron-containing materials.
Abstract The efficiencies of iron-containing catalysts for the reduction of nitric oxide in simulated and real exhaust gases are reported. The catalyst bed was seven times the swept volume of the engine. The best results were obtained when the engines were run about 10 per cent rich of stoicheiometric. The rate at which the catalyst was poisoned by conventional fuel additives was shown to be reduced by raising the working temperature of the reactor.
Micro and Macro Changes in a Stainless Steel Catalyst during Reduction of NO
A newly constructed 304 stainless steel recycle batch reactor was found to be significantly reactive to NO above 250°C. The extent of reactivity depended upon pretreatment schedules used and whether the reactor surfaces were in ah oxidized or reduced state. This work suggests that a breakdown of the protective chromium oxide surface caused by cyclic oxidizing and reducing atmospheres leads to the development of a large surface roughness. Further work with supported iron and chromium oxides substantiates this mechanism.
Enhancement of surface properties on Low Density Polyethylene packaging films using various fluorination routes
Nowadays, packaging market deployment requires an important attention. Influence of treatment with molecular (F2) or atomic (Fradical dot) fluorine on properties of Low Density Polyethylene (LDPE) films was investigated. The films were treated using direct fluorination conditions with F2 or a specific reagent XeF2, which releases atomic fluorine Fradical dot. Changes of LDPE chemical composition were investigated by FTIR and solid state NMR. Surface morphology was studied by several microscopy techniques (SEM and AFM). Finally to further characterize film properties after treatments, surface energy measurements and electron paramagnetic resonance (EPR) analyses were also carried out. An upper fluorinated layer, which contains mainly high amount of single bondCF2single bond, was formed during the direct fluorination conditions (F2). For the process performed with XeF2, specific groups single bondCHFsingle bond were detected not only on the polymer surface but also in the bulk. The final CHF/CF2 ratio depended on the fluorination route. Treatment with Fradical dot (originated from XeF2 decomposition) resulted in single bondCHFsingle bond groups in bulk prevailing formation whereas F2 formed mainly single bondCF2single bond groups. Regardless to the reactive species, radicals (dangling bonds) appeared during the fluorination and reacted with oxygen during the exposition to air after the treatment. Such a process resulted in oxygenated polar groups formation and consequently in the surface energy increase.