Active nitrogen with hydrocarbons

Chemiluminescent Reactions of Active Nitrogen with Hydrocarbons... 

Figure 6 CN(B2X+ —> X2T ) emission in the reaction of active nitrogen with hydrocarbons. (Reprinted with permission from Ref. 58. Copyright 1979 American Chemical Society.)...

Perhaps the best-known example of chemiluminescence is the emission of the red (A2U.-X2H+) and violet (B2E+-Ar22+) systems of CN from mixtures of active nitrogen with hydrocarbons, halogenated hydrocarbons, or molecules containing a CN group. Almost certainly, all three types of excitation mechanism operate. 

The relative intensities of the CN bands depend strongly on the nature of the species added to active nitrogen [145, 146], With halogenated hydrocarbons, red emission from the A 2II state predominates this was classified by Bayes [146] as the P2 emission. The v distribution is broad, peaking at v = 7, and the red system is accompanied by bands from B 2S+ v = 0) that is populated via A 2II (y = 10) because of perturbations and collision-induced transitions. The Pa emission from mixtures of active nitrogen with halogen-containing compounds is quite different, and the relative band intensities in the red system show that v = 0 is now the most populated level. 

In addition to the ability to react nonspecifically with hydrocarbons, active nitrogen can readily participate in energy transfer reactions with volatile organometal-lic compounds, leading to atomic emission from the metal atom. By use of appropriate optical filters, selective detection of elements such as aluminum, lead, tin, and mercury has been achieved in the presence of large excesses of organics [58],... 

The reactions of fluorine atoms with hydrocarbons are similar to those of active nitrogen in that they provide an essentially universal response. Fluorine atoms abstract H atoms from hydrocarbons at near-collisional reaction rates. Reactions with fluorine are highly exothermic, forming strong H—F (=570 kJ mol-1) and C—F (=485 kJ mol-1) bonds while breaking much weaker C—H (=414 kJ mor1) and C—C (=368 kJ mol-1) bonds. The hydrogen abstraction reaction... 

The polymer, in spherical form with particle size ranging from approximately 0.5 mm to 3 mm, is then discharged in a receiver recovering the resultant gas (6) and to a proprietary unit for monomer stripping and neutralization of any remaining catalyst activity (7). Residual hydrocarbons in the polymer are stripped out and recycled back to reaction. The polymer is dried by a closed-loop nitrogen system (8) and with no volatile substances, is sent to liquid and/or solid additives incorporation step before extrusion (9). 

Zeolites have also proven applicable for removal of nitrogen oxides (NO ) from wet nitric acid plant tail gas (59) by the UOP PURASIV N process (54). The removal of NO from flue gases can also be accomplished by adsorption. The Unitaka process utilizes activated carbon with a catalyst for reaction of NO, with ammonia, and activated carbon has been used to convert NO to N02, which is removed by scrubbing (58). Mercury is another pollutant that can be removed and recovered by TSA. Activated carbon impregnated with elemental sulfur is effective for removing Hg vapor from air and other gas streams the Hg can be recovered by ex situ thermal oxidation in a retort (60). The UOP PURASIV Hg process recovers Hg from clilor-alkali plant vent streams using more conventional TSA regeneration (54). Mordenite and clinoptilolite zeolites are used to remove HQ from Q2, clilorinated hydrocarbons, and reformer catalyst gas streams (61). Activated aluminas are also used for such applications, and for the adsorption of fluorine and boron—fluorine compounds from alkylation (qv) processes (50). 

Positive effects of phosphorus have been reported primarily for HDN reactions for converting both model compounds and industrial feeds. Tops0e et al (98) indicated that indole HDN is enhanced by phosphorus addition. Similarly. Eijsbouts et al (37, 94) reported that quinoline HDN activity increases with the addition of phosphorus, especially to Ni—Mo —P/Al catalysts. They also observed that phosphorus addition increases the selectivity for the production of unsaturated nitrogen-free hydrocarbons (e.g., propylbenzene). On the other hand, Poulet et al (79, 95), Jian and Prins (81) and Rico Cerda and Prins (130) reported that phosphorus has a negative influence on pyridine HDN catalyzed by MoP/ Al. The apparently contradictory nature of these results leaves the... 

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