Ethane utilization

Oxygen incorporation in methyl ketones does not imply that this is the sole entry of O2 during the metabolism of the gaseous alkanes. On the contrary, Oj incorporation occurs during methane or ethane utilization where methyl ketone formation is impossible. Also, methyl ketone formation has not been detected during utilization of longer chain alkanes. Furthermore, as will be seen below, O2 incorporation in the terminal carbon of long-chain alkanes has been demonstrated. 

Essentially all of the methane [74-82-8] is removed ia the demethanizer overhead gas product. High recovery of ethane and heavier components as demethanizer bottoms products is commonplace. The work that is generated by expanding the gas ia the turboexpander is utilized to compress the residue gas from the demethanizer after it is warmed by heat exchange with the inlet gas. Recompression and deUvery to a natural gas pipeline is performed downstream of the plant. A propane recovery of 99% can be expected when ethane recoveries are ia excess of 65%. 

The only method utilized commercially is vapor-phase nitration of propane, although methane (70), ethane, and butane also can be nitrated quite readily. The data in Table 5 show the typical distribution of nitroparaffins obtained from the nitration of propane with nitric acid at different temperatures (71). Nitrogen dioxide can be used for nitration, but its low boiling point (21°C) limits its effectiveness, except at increased pressure. Nitrogen pentoxide is a powerful nitrating agent for alkanes however, it is expensive and often gives polynitrated products. 

The high T] values above conflict with the common behef that distillation is always inherendy inefficient. This behef arises mainly because past distillation practices utilized such high driving forces for pressure drop, tedux ratio, and temperature differentials in teboilets and condensers. A teal example utilizing an ethane—ethylene sphtter follows, in which the relative number for the theoretical work of separation is 1.0, and that for the net work potential used before considering driving forces is 1.4. 

Other Reactions. Comprehensive discussions of the foUowiag reactions, which are primarily of academic iaterest, are provided ia various refereaces (10,17). Ethyleae may be hydrogeaated to ethane under a variety of conditions. Eor example, hydrogenation is feasible for systems utilizing finely... 

Vinyl chloride is an important monomer for polyvinyl chloride (PVC). The main route for obtaining this monomer, however, is via ethylene (Chapter 7). A new approach to utilize ethane as an inexpensive chemical intermediate is to ammoxidize it to acetonitrile. The reaction takes place in presence of a cobalt-B-zeolite. 

Direct conversion of methane to ethane and ethylene (C2 hydrocarbons) has a large implication towards the utilization of natural gas in the gas-based petrochemical and liquid fuels industries [ 1 ]. CO2 OCM process provides an alternative route to produce useful chemicals and materials where the process utilizes CO2 as the feedstock in an environmentally-benefiting chemical process. Carbon dioxide rather than oxygen seems to be an alternative oxidant as methyl radicals are induced in the presence of oxygen. Basicity, reducibility, and ability of catalyst to form oxygen vacancies are some of the physico-chemical criteria that are essential in designing a suitable catalyst for the CO2 OCM process [2]. The synergism between catalyst reducibility and basicity was reported to play an important role in the activation of the carbon dioxide and methane reaction [2]. 

Hydrolysis to the diol followed by dehydration to the aldehyde and oxidation to the carboxylic acid is used by a propene-utilizing species of Nocardia (de Bont et al. 1982). Although an ethene-utilizing strain of Mycobacterium sp. strain E44 degrades ethane-l,2-diol by this route, the diol is not an intermediate in the metabolism of the epoxide (Wiegant and de Bont 1980). 

Fig. 2.12. Enthalpy, entropy, and free energy differences for the ethane —> ethane zero-sum alchemical transformation in water. The molecular dynamics simulations are similar to those described in Fig. (2.7). 120 windows (thin lines) and 32 windows (thick lines) of uneven widths were utilized to switch between the alternate topologies, with, respectively, 20 and lOOps of equilibration and 100 and 500 ps of data collection, making a total of 14.4 and 19.2 ns. The enthalpy (dashed lines) and entropy (dotted lines) difference amount to, respectively, —0.1 and +1.1 kcalmol-1, and —0.5 and +4.1 calmol-1 K For comparison purposes, the free energy difference is equal to, respectively, +0.02 and —0.07kcalmol I, significantly closer to the target value. Inset Convergence of the different thermodynamic quantities...

Double hydrophilic star-block (PEO-fo-PAA)3 copolymers were prepared by a combination of anionic and ATRP of EO and fBuA [150]. Three-arm PEO stars, with terminal - OH groups were prepared by anionic polymerization, using l,l,l-tris(hydroxymethyl)ethane, activated with DPMK as a trifunctional initiator. The hydroxyl functions were subsequently transformed to three bromo-ester groups, which were utilized to initiate the polymerization of f-butyl acrylate by ATRP in the presence of CuBr/PMDETA. Subsequent hydrolysis of the f-butyl groups yielded the desired products (Scheme 74). 

The transfer reaction utilizes a sacrificial alkene to remove the dihydrogen from the pincer or anthraphos complex first, before the oxidative addition of the target alkane. The elementary reaction steps are slightly different from the thermal reaction, which is discussed in the next section, both in their order and their direction. For simplicity, we describe the symmetric reaction where the sacrificial alkene is ethylene and the reactant is ethane (21b). The elementary reaction steps for the mechanism of this transfer reaction involve IVR, IIIR, VIR, VI, III and IV, where the superscript R stands for the reverse of the elementary steps listed in Section III. These reverse steps (IVR, IIIR, and VIR) involve the sacrificial alkene extracting dihydride from the metal to create the Ir(I) species 8, while steps VI, III and IV involve oxidative addition of target alkane, p-H transfer and olefin loss. 

The first report of rhodium catalysts for aldehyde reduction came from Marko who reported the use of RhCl3 3H20 under hydroformylation conditions [9]. It was suggested that the active species were rhodium carbonyls, and the catalyst system was successfully utilized in the hydrogenation of ethanal, propanal, and benzalde-... 

As discussed in Section 3.3.2, Corey demonstrated the utility of compound 55, prepared from 1,2-diphenyl-1,2-diamino ethane 54, as a chiral auxiliary for asymmetric aldol reaction. In a similar manner, his group utilized this compound 55 in both (R,R)- and (A,A)-forms for allylation reactions. Treatment of 55 with allyltributyltin in dry CH2CI2 at 0°C and then 23°C for 2 hours gives chiral allyl-borane 135. In this process, both the (R,R)- and (A,A)-forms can be obtained and applied in asymmetric allylation reactions. Thus, treatment of... 

The static system studies carried out by Lambert47 utilized Zn(CH3)2, Zn(CD3)2, C6H12 and C6D12. The decomposition of Zn(CH3)2 in the presence of C6D12 was studied with C6D12/Zn(CH3)2 ratios of 0-17. At 348 °C using a ratio of 13, the gaseous products contained 97.5 % methane, 1.6 % ethane plus ethylene... 

Maymo-Gatell, X., Tandoi, V., Gossette, J., and Zinder, S. H., 1997, Characterization of an H2-utilizing emichment culture that reductively dechlorinates tetrachloroethene to vinyl chloride and ethane in the absence of methanogenesis and acetogenesis, Appl. Environ. 

Barnett and co-workers recently reported that it might be possible to utilize hydrocarbons directly in SOFC with Ni-based anodes. " ° First, with methane. they observed that there is a narrow temperature window, between 550 and 650 °C. in which carbon is not as stable. The equilibrium constant for methane dissociation to carbon and Hz is strongly shifted to methane below 650 °C. and the equilibrium constant for the Boudouard reaction, the disproportionation of CO to carbon and COz, is shifted to CO above 550 °C. Therefore, in this temperature range, they reported that it is possible to operate the cell in a stable manner. (However, a subsequent report by this group showed that there is no stable operating window for ethane due to the fact that carbon formation from ethane is shifted to lower temperatures. ) In more recent work, this group has suggested that, even when carbon does form on Ni-based anodes, it may be possible to remove this carbon as fast as it forms if the flux from the electrolyte is sufficient to remove carbon faster than it is formed.Observations by Weber et al. have confirmed the possibility of stable operation in methane. Similarly, Kendall et al. showed that dilution of methane with COz caused a shift in the reaction mechanism that allowed for more stable operation. 

The synthesis and characterization of the complexes [RuL(H20)] and [Ru2L(H20)2] in which H4L is ethane-1,T,2,2 -tetra(thioglycolic acid) have been reported. It is proposed from spectroscopic data that each complex contains five-coordinate Ru and that H2L acts as an S202-donoi, while L utilizes eight donor atoms. [RuL(H20)] and [Ru2L(H20)2] react with CO, PPhs, or NO, and the site of addition is proposed to be trans to the aqua ligand in each case. ... 

Tsuji, H. Kobayashi, T. Ohmura, R. Mori, Y.H. (2005a). Hydrate Formation by Water Spraying in a Methane + Ethane + Propane Gas Mixture An Attempt at Promoting Hydrate Formation Utilizing LMGS for sH Hydrates. Energy and Fuel, 19, 869-876. 

We developed a method for the synthesis of a variety of cyclic acetals that utilizes bismuth triflate as a catalyst and does not require the use of a Dean-Stark trap for removal of water [102]. In this method, an aldehyde or ketone is treated with 1,2-bis (trimethylsiloxy)ethane in the presence of bismuth triflate. A comparison study using o-chlorobenzaldehyde showed that with ethylene glycol a low conversion to the dioxolane was observed after 2 h whereas the use of the 1,2-bis(trimethylsiloxy) ethane afforded the corresponding dioxolane in good yields. (Scheme 9). 

---