Hydrocarbon higher

All these fuel gases contain more than 50 % hydrogen and 10-30% methane, the other main components being CO, higher hydrocarbons, CO2 and Nj. In many parts of the world natural gas of calorific value of approximately 38MJ/m has become the widely-used gaseous fuel. 

One can effectively reduce the tliree components to two with quasibinary mixtures in which the second component is a mixture of very similar higher hydrocarbons. Figure A2.5.31 shows a phase diagram [40] calculated from a generalized van der Waals equation for mixtures of ethane n = 2) with nomial hydrocarbons of different carbon number n.2 (treated as continuous). It is evident that, for some values of the parameter n, those to the left of the tricritical point at = 16.48, all that will be observed with increasing... 

Figure A2.5.31. Calculated TIT, 0 2 phase diagram in the vicmity of the tricritical point for binary mixtures of ethane n = 2) witii a higher hydrocarbon of contmuous n. The system is in a sealed tube at fixed tricritical density and composition. The tricritical point is at the confluence of the four lines. Because of the fixing of the density and the composition, the system does not pass tiirough critical end points if the critical end-point lines were shown, the three-phase region would be larger. An experiment increasing the temperature in a closed tube would be represented by a vertical line on this diagram. Reproduced from [40], figure 8, by pennission of the American Institute of Physics.

Elimination of halogen by sodium (Wurtz s reaction) gives a higher hydrocarbon. 

Aliphatic hydrocarbons can be prepared by the reduction of the readily accessible ketones with amalgamated zinc and concentrated hydrochloric acid (Clemmensen method of reduction). This procedure is particularly valuable for the prep>aration of hydrocarbons wdth an odd number of carbon atoms where the Wurtz reaction cannot be applied with the higher hydrocarbons some secondary alcohol is produced, which must be removed by repeated distillation from sodium. 

Shake 1 ml. of anhydrous methyl alcohol with 1 ml. of paraffin oil. Repeat the experiment with 1 ml. of n butyl alcohol. From your results state which is the better solvent for paraffin oil (a mixture of higher hydrocarbons) and thus explain why n-butanol and higher alcohols are incorporated in pyroxylin lacquers in preference to methyl and ethyl alcohols. 

Liquid fuels methanol, ethanol, higher hydrocarbons, oils Chemicals... 

The direct methane conversion technology, which has received the most research attention, involves the oxidative coupling of methane to produce higher hydrocarbons (qv) such as ethylene (qv). These olefinic products may be upgraded to Hquid fuels via catalytic oligomerization processes. 

In the classical normal pressure synthesis (16), higher hydrocarbons are produced by net reactions similar to those observed in the eady 1900s, but at temperatures below the level at which methane is formed ... 

Liquid Fuels via Methanol Synthesis and Conversion. Methanol is produced catalyticaHy from synthesis gas. By-products such as ethers, formates, and higher hydrocarbons are formed in side reactions and are found in the cmde methanol product. Whereas for many years methanol was produced from coal, after World War II low cost natural gas and light petroleum fractions replaced coal as the feedstock. 

Generally, the most developed processes involve oxidative coupling of methane to higher hydrocarbons. Oxidative coupling converts methane to ethane and ethylene by... 

Ethane. Ethane VPO occurs at lower temperatures than methane oxidation but requires higher temperatures than the higher hydrocarbons (121). This is a transition case with mixed characteristics. Low temperature VPO, cool flames, oscillations, and a NTC region do occur. At low temperatures and pressures, the main products are formaldehyde, acetaldehyde (HCHOiCH CHO ca 5) (121—123), and carbon monoxide. These products arise mainly through ethylperoxy and ethoxy radicals (see eqs. 2 and 12—16 and Fig. 1). 

Higher Hydrocarbons. The VPO of higher hydrocarbons is similar to that of the lower members of the series with two significant additional comphcations (/) the back-bitiag reactions of alkylperoxy radicals (eq. 32), particularly at positions 2 or 3 carbons removed from the peroxy position, and (2) above the NTC region, radical fragmentation (eq. 28). 

Acetone is a coproduct of butane LPO. Some of this is produced from isobutane, an impurity present in all commercial butane (by reactions 2, 13, 14, and 16). However, it is likely that much of it is produced through the back-biting mechanisms responsible for methyl ketone formation in the LPO of higher hydrocarbons (216). 

Synthesis gas is used in the production of substitute natural gas (SNG), ie, methane, and higher hydrocarbons. 

The impurities usually found in raw hydrogen are CO2, CO, N2, H2O, CH, and higher hydrocarbons. Removal of these impurities by shift catalysis, H2S and CO2 removal, and the pressure-swing adsorption (PSA) process have been described (vide supra). Traces of oxygen in electrolytic hydrogen are usually removed on a palladium or platinum catalyst at room temperature. 

Potential Processes. Sulfur vapor reacts with other hydrocarbon gases, such as acetjiene [74-86-2] (94) or ethylene [74-85-1] (95), to form carbon disulfide. Higher hydrocarbons can produce mercaptan, sulfide, and thiophene intermediates along with carbon disulfide, and the quantity of intermediates increases if insufficient sulfur is added (96). Light gas oil was reported to be successflil on a semiworks scale (97). In the reaction with hydrocarbons or carbon, pyrites can be the sulfur source. With methane and iron pyrite the reaction products are carbon disulfide, hydrogen sulfide, and iron or iron sulfide. Pyrite can be reduced with carbon monoxide to produce carbon disulfide. 

Higher hydrocarbons are formed by the polymerisation of ethylene. Any higher unsaturated hydrocarbons present are converted to the corresponding alcohols by hydration. 

Activated alumina and phosphoric acid on a suitable support have become the choices for an iadustrial process. Ziac oxide with alumina has also been claimed to be a good catalyst. The actual mechanism of dehydration is not known. In iadustrial production, the ethylene yield is 94 to 99% of the theoretical value depending on the processiag scheme. Traces of aldehyde, acids, higher hydrocarbons, and carbon oxides, as well as water, have to be removed. Fixed-bed processes developed at the beginning of this century have been commercialized in many countries, and small-scale industries are still in operation in Brazil and India. New fluid-bed processes have been developed to reduce the plant investment and operating costs (102,103). Commercially available processes include the Lummus processes (fixed and fluidized-bed processes), Halcon/Scientific Design process, NIKK/JGC process, and the Petrobras process. In all these processes, typical ethylene yield is between 94 and 99%. 

The oxidation of hydrocarbons involves the sequential formation of a number of similar reactions in which various intermediate radicals which are combinations of carbon, hydrogen and oxygen are formed. In the simplest case, the oxidation of medrane, the methyl radical CH3 plays an important part both in direct oxidation to CO(g) and in indirect oxidation duough the formation of higher hydrocarbons such as CaHe before CO is formed. The chain reactions include... 

Similar expressions have been found to be applicable to the steam reforming of higher hydrocarbons. For example, it has been shown that if it is assumed that ethane, CaHg is adsorbed on two neighbouring sites, the overall reaction rate can be expressed by the equation... 

The characteristic magnitudes of detonation cells for various fuel-air mixtures (Table 3.2) show that these restrictive boundary conditions for detonation play only a minor role in full-scale vapor cloud explosion incidents. Only pure methane-air may be an exception in this regard, because its characteristic cell size is so large (approximately 0.3 m) that the restrictive conditions, summarized above, may become significant. In practice, however, methane is often mixed with higher hydrocarbons which substantially augment the reactivity of the mixture and reduce its characteristic-cell size. 

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