Oxygen propene

A silica-supported Sn—V—P—O catalyst (Sn/V/P = 1/9/3) was investigated by Onsan and Trimm [244]. Working with a flow reactor at about 520°C, a maximum selectivity of 75% to acrylonitrile was reached at a contact time of ca. 230 g sec l-1 and an oxygen/propene/ammonia ratio of 2/1/1.75. The authors assume that the six principal products (acrylonitrile, acetonitrile, HCN, CO, C02, N2) are formed by six parallel reactions and in the first instance apply power rate equations. A more detailed analysis reveals that a Langmuir—Hinshelwood type rate equation, surface reaction being rate-determining, properly describes the production of acrolein plus acrylonitrile from propene, viz. 

In the case of alumina (or other simple oxides), the reaction occurs at high temperatures and under low space velocity conditions. The activity was found to be improved by the addition of platinum group metals [13, 14] and of transition metal oxides [15], especially copper [16, 17, 18]. For alumina-supported copper oxide catalysts a maximum effect has been found by the addition of 0.3 wt % Cu and it has been considered that, for higher copper contents, the formation of cupric oxide would give a solid selective for the oxidation of the hydrocarbon by oxygen [16]. In the case of alumina-supported Cu-Cs oxide catalysts the formation of an isocyanate species has been evidenced by exposition to mixtures "nitric oxide/oxygen/propene (or acetylene)" but not with propane [18, 19], In fact the mechanism of the reaction and the nature of the active sites are still unknown. 

What goes on in this conversion is that the p-Nitropropene undergoes a catalytic reduction whereby it loses its propene double bond, and the nitro s oxygens get replaced with hydrogens. All this happens in one pot with, usually, just one reaction. 

Many of the reactions we ve already encountered can yield a chiral product from an achi ral starting material Epoxidation of propene for example creates a chirality center by adding oxygen to the double bond... 

Figure 7 7 shows why equal amounts of (R) and (5) 1 2 epoxypropane are formed m the epoxidation of propene There is no difference between the top face of the dou ble bond and the bottom face Peroxyacetic acid can transfer oxygen to either face with equal facility the rates of formation of the R and S enantiomers of the product are the same and the product is racemic... 

An important nitrile is acrylonitrile H2C=CHCN It is prepared industrially from propene ammonia and oxygen m the presence of a special catalyst Polymers of acryl omtrile have many applications the most prominent being their use m the preparation of acrylic fibers... 

Typical isobutylene, as suppHed to the butyl mbber process, has a purity in the range of 95—99%, and includes varying amounts of propene, 1-butene, 2-butene, isobutylene dimer, and tert-huty alcohol, and trace quantities of a variety of oxygen-containing compounds, depending on the process employed. 

The important hydrocarbon classes are alkanes, alkenes, aromatics, and oxygenates. The first three classes are generally released to the atmosphere, whereas the fourth class, the oxygenates, is generally formed in the atmosphere. Propene will be used to illustrate the types of reactions that take place with alkenes. Propene reactions are initiated by a chemical reaction of OH or O3 with the carbon-carbon double bond. The chemical steps that follow result in the formation of free radicals of several different types which can undergo reaction with O2, NO, SO2, and NO2 to promote the formation of photochemical smog products. 

Examine the geometry and electrostatic potential map for acetone enolate. Are the CC and CO bonds in the enolate more similar to those in acetone or propen-2-ol precursors Is the negative charge primarily located on oxygen or on carbon Assuming this enolate is a hybrid of the two resonance contributors as shown above, which, if either, appears to be the major contributor ... 

Figure 14.7 Typical clnomatogram obtained by using the refinery analyser system shown in Figure 14.6. Peak identification is as follows 1, hydrogen 2, Cg+, 3, propane 4, acetylene 5, propene 6, hydrogen sulfide 6, iso-butane 8, propadiene 9, n-butane, 10. iso-butene 11, 1-butene 12, traw-2-butene 13, cw-2-butene 14, 1,3-butadiene 15, iso-pentane 16, w-pen-tane 17, 1-pentene 18, tro 5-2-pentene 19, cw-2-pentene 20, 2-inethyl-2-butene 21, carbon dioxide 22, ethene 23, ethane 24, oxygen + argon, 25, niti Ogen, 26, carbon monoxide.

The oxidation of propene on Pt/YSZ was studied28 at temperatures 350° to 500°C. Figure 8.19 shows SEMs of the porous Pt/YSZ film which has a surface area corresponding to a reactive oxygen uptake NG=6.8-10 7 mol O. 

Reduced nicotinamide-adenine dinucleotide (NADH) plays a vital role in the reduction of oxygen in the respiratory chain [139]. The biological activity of NADH and oxidized nicotinamideadenine dinucleotide (NAD ) is based on the ability of the nicotinamide group to undergo reversible oxidation-reduction reactions, where a hydride equivalent transfers between a pyridine nucleus in the coenzymes and a substrate (Scheme 29a). The prototype of the reaction is formulated by a simple process where a hydride equivalent transfers from an allylic position to an unsaturated bond (Scheme 29b). No bonds form between the n bonds where electrons delocalize or where the frontier orbitals localize. The simplified formula can be compared with the ene reaction of propene (Scheme 29c), where a bond forms between the n bonds. 

As is outlined for ene reactions of singlet oxygen in Scheme 15, the prototypical ene reaction starts with the electron delocalization from the HOMO of propene to the LUMO of X=Y. The delocalization from the HOMO, a combined n and orbital with larger amplitude on n, leads to a bond formation between the C=C and X=Y bonds. Concurrent elongation of the bond enables a six-membered ring transition stracture, where partial electron density is back-donated from the LUMO of X=Y having accepted the density, to an unoccupied orbital of propene localized on the bond. As a result, the partial electron density is promoted (pseudoex-cited) from the HOMO (it) to an unoccupied orbital (ct n ) of alkenes. This is a reaction in the pseudoexcitation band. 

For the analysis of the chemical structure of flames, laser methods will typically provide temperature measurement and concentration profiles of some readily detectable radicals. The following two examples compare selected LIF and CRDS results. Figure 2.1 presents the temperature profile in a fuel-rich (C/O = 0.6) propene-oxygen-argon flame at 50 mbar [42]. For the LIF measurements, 1% NO was added. OH-LIF thermometry would also be possible, but regarding the rather low OH concentrations in fuel-rich flames, especially at low temperatures, this approach does not capture the temperature rise in the flame front [43]. The sensitivity of the CRDS technique, however, is superior, and the OH mole fraction is sufficient to follow the entire temperature profile. Both measurements are in excellent agreement. For all flames studied here, the temperature profile has been measured by LIF and/or CRDS. 

Kohse-Hoinghaus, K. et al.. The influence of ethanol addition on premixed fuel-rich propene-oxygen-argon flames, Proc. Combust. Inst., 31,1119, 2007. 

As a new kind of carbon materials, carbon nanofilaments (tubes and fibers) have been studied in different fields [1]. But, until now far less work has been devoted to the catalytic application of carbon nanofilaments [2] and most researches in this field are focused on using them as catalyst supports. When most of the problems related to the synthesis of large amount of these nanostructures are solved or almost solved, a large field of research is expected to open to these materials [3]. In this paper, CNF is tested as a catalyst for oxidative dehydrogenation of propane (ODP), which is an attractive method to improve propene productivity [4]. The role of surface oxygen annplexes in catalyzing ODP is also addressed. 

It is found that the CNF-HT has not catalytic activity for ODP. After oxidation, all the three samples show hi ly catalytic performances, which are shown in Fig.3. CNF-HL has the longest induction period among the three samples, and it has relatively low activity and propene selectivity at the beginning of the test. During the induction periods, the carbon balance exceeds 105% and then fall into 100 5%, which implies the CNF structure is stable and the surface chemistry of CNF reaches a dynamic equilibrium eventually. These results indicate that the catalytic activity of ODP can be attributed to the existence of surface oxygen complexes which are produced by oxidation. The highest propene yield(lS.96%) is achieve on CNF-HL at a 52.97% propane conversion. 

C04-0004. Acrylonitrile is used to make s Tithetic fibers such as Orion. About t.5 billion kg of acrylonitrile are produced each year. Balance the following chemical equation, which shows how acrylonitrile is made from propene, ammonia, and oxygen ... 

Acrylonitrile Is produced from propene, ammonia, and oxygen by the following balanced equation (see Example 14-5) 2 C3 Hg + 2 NH3 + 3 O2 2 CH2 CHCN -1- 6 H2 O Relate the rates of reaction of starting materials and products. 

The balanced equation shows that three molecules of oxygen are consumed for every two molecules of propene and two molecules of ammonia. Thus, the rate of C3 Hg and NH3 consumption is only two-thirds the rate of O2 consumption. Those seven molecules of starting materials produce two molecules of CH2 CHCN and six molecules of H2 O. Thus, CH2 CHCN is produced at the same rate as C3 Hg is consumed, whereas H2 O is produced three times as fast as CH2 CHCN is. The link between relative reaction rates and reaction stoichiometry is Equation. Therefore,... 

However, in the same temperature range and O2 partial pressure total oxidation of acrolein and propene largely predominates. This can be taken as a further support that on transition metal oxide catalysts the same oxygen species (lattice oxygen) are involved in both partial and total oxidation. 

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