Propene-oxygen-nitrogen

Fig. 2.9-1 Explosion diagram for propene-oxygen-nitrogen [Fehlings 1998].

Tanaka, T Okuhara, T Misono, M. Intermediacy of organic nitro and nitrite surface species in selective reduction of nitrogen monoxide by propene in the presence of excess oxygen over silica-supported platinum. Appl. Catal, B Environmental, 1994, Volume 4, Issue 1, L1-L9. 

Yokoyama, C. and Misono, M. Catalytic reduction of nitrogen oxides by propene in the presence of oxygen over cerium ion-exchanged zeolites II. Mechanistic study of roles of oxygen and doped metals. J. Catal, 1994, Volume 150,9-17. 

The hypothesis of a bifunctional mechanism involving allyl radical formation and oxygen incorporation on distinct sites is advocated by Haber et al. [147,152], This hypothesis is particularly based on experiments with Mo03, Bi203 and mechanical mixtures of these oxides, which are compared with bismuth molybdate catalysts. The reaction was carried out in cyclic operation (alternating feeds of oxygen and of propene diluted with nitrogen). The results are collected in Table 5. The authors con-... 

Wise [350] investigated the parallel between ammoxidation and oxidation of ammonia over bismuth molybdates. It was shown that the rate of conversion to nitrogen is first order in NH3 and independent of oxygen concentration, analogous to the selective oxidation of propene. Under conditions in which propene combusts, NH3 is converted to nitrogen oxides. 

Figure 14.7 Typical chromatogram obtained by using the refinery analyser system shown in Figure 14.6. Peak identification is as follows 1, hydrogen 2, C6+, 3, propane 4, acetylene 5, propene 6, hydrogen sulfide 6, iso-butane 8, propadiene 9, n-butane, 10. iso-butene 11, 1-butene 12, trans-2-b itene 13, cw-2-butene 14, 1,3-butadiene 15, iso-pentane 16, n-pentane 17,1-pentene 18, fram -pentene 19, cw-2-pentene 20, 2-methyl-2-butene 21, carbon dioxide 22, ethene 23, ethane 24, oxygen + argon, 25, nitrogen, 26, carbon monoxide.

The effect of nitric oxide or oxygen on the photolysis of cis- or trflnj-butene-2 was quite striking The yields of ethane, propene, -butane, butene-1, isobutane and Cj to Cg compounds were reduced sharply to levels well below those from corresponding runs with nitrogen. In contrast, allene, methane, ethylene, acetylene, butene-2 and butadiene were affected only to the same extent as the runs with nitrogen. It is concluded that the products in the latter group are primary while those of the former group are secondary and arise from free radicals produced in primary steps. 

A kinetic model [15], with adapted kinetic parameters [25], was used, which accounts for oxidation by oxygen of carbon monoxide, propene, methane, and hydrogen, and also includes inhibition effects caused by nitrogen oxide. The following net production rates were applied in Eq. (26) ... 

Intramolecular vinylation of Lewis acid-activated carbon electrophiles with vinylsilanes is very valuable for construction of carbocycles and oxygen- or nitrogen-containing heterocycles [4]. In contrast, fhere are few reports of intermolecular vinylation [525]. Schaumann et al. recently reported TiCl4-promoted vinylation of epoxides wifh l,3-bis(trimethylsilyl)-l-propene (Scheme 10.200) [526]. 

Plant design for the direct oxidation of propene would most likely be based on pure oxygen feed, rather than air, to gain yield advantage and lower capital costs. The minimal purge gas flow in an oxygen-based process makes it economically feasible to use a ballast gas (diluent) other than nitrogen. 

Prior to each reaction test and spectroscopic measurement, the sample was treated with 100 Torr oxygen (1 Torr = 133.3 N m ) at 673 K for 1 h, followed by evacuation at 673 K for 1 h. The photooxidation of propene was performed with a conventional closed system (123 cm ). The sample (200 mg) was spread on the flat bottom (12.6 cm ) of the quartz vessel. Propene (100 pmol, 15 Torr) and oxygen (200 pmol, 30 Torr) were introduced into the vessel, and the sample was irradiated by a 200 W Xe lamp. After collecting the products in gas phase, the catalyst bed was heated at 573 K in vacuo to collect the products adsorbed on the catalyst by a liquid nitrogen trap. These products were separately analyzed by GC. The results presented here are the sum of each product yield. 

---