Nitrogen from methane

A membrane separator is to be used for separating nitrogen from methane as specified below ... 

The separation of nitrogen from natural gas reHes on the differences between the boiling points of nitrogen (77.4 K) and methane (91.7 K) and involves the cryogenic distillation of a feed stream that has been preconditioned to very low levels of carbon dioxide, water vapor, and other constituents that would form soHds at the low processing temperatures. 

A flow diagram for the system is shown in Figure 5. Feed gas is dried, and ammonia and sulfur compounds are removed to prevent the irreversible buildup of insoluble salts in the system. Water and soHds formed by trace ammonia and sulfur compounds are removed in the solvent maintenance section (96). The pretreated carbon monoxide feed gas enters the absorber where it is selectively absorbed by a countercurrent flow of solvent to form a carbon monoxide complex with the active copper salt. The carbon monoxide-rich solution flows from the bottom of the absorber to a flash vessel where physically absorbed gas species such as hydrogen, nitrogen, and methane are removed. The solution is then sent to the stripper where the carbon monoxide is released from the complex by heating and pressure reduction to about 0.15 MPa (1.5 atm). The solvent is stripped of residual carbon monoxide, heat-exchanged with the stripper feed, and pumped to the top of the absorber to complete the cycle. 

A low calorific value gas, which includes nitrogen from air, could be produced for boiler or turbine use in electric power production, or an intermediate calorific value gas containing no nitrogen for an industrial fuel gas, or synthesis gas for chemical and methane production could be provided. This approach which has been studied in Russia, Europe, Japan, and the United States, is stiU noncommercial in part because it is not economically competitive. 

In the BMA process, methane (natural gas) and ammonia are reacted without air being present (44). The reaction is carried out in tubes that are heated externally to supply the endothermic heat of reaction very similar to a reformer. Yield from ammonia and methane is above 90%. The off-gas from the converter contains more than 20 mol % hydrogen cyanide, about 70 mol % hydrogen, 3 mol % ammonia, 1 mol % methane, and about 1 mol % nitrogen from ammonia decomposition. 

The first clearly authenticated preparation of an isoindole was reported by Wittig et in 1951. It was found that elimination from isoindolinium bromides and iodides with bases such as aryl- and alkyllithium afforded 2-substituted isoindoles in variable yields. For instance, 2,2-dimethylisoindolinium bromide (5) on treatment with one equivalent of phenyllithium in ether under nitrogen, evolved methane and gave 2-mcthylisoindole (6) in 74% yield. With methyl-lithium as base, a slightly lower yield was obtained. 

In gas separation with membranes, a gas mixture at an elevated pressure is passed across the surface of a membrane that is selectively permeable to one component of the mixture. The basic process is illustrated in Figure 16.4. Major current applications of gas separation membranes include the separation of hydrogen from nitrogen, argon and methane in ammonia plants the production of nitrogen from ah and the separation of carbon dioxide from methane in natural gas operations. Membrane gas separation is an area of considerable research interest and the number of applications is expanding rapidly. 

C16-0020. Chemists are optimistic that a catalyst will be found for the production of ammonia from hydrogen and nitrogen under standard conditions. In contrast, no hope exists of developing a catalyst for the production of hydrogen from methane and steam under standard conditions. Explain. 

Studies carried out on Earth, for example, by the NASA infrared telescope on Mauna Kea (Hawaii), showed albedo variations which indicated the presence of holes in the Titanian cloud formations (Griffith, 1993). It is, however, still unclear as to whether these inhomogeneities result from differences in the surface composition. Lorenz et al. (1997) reported large variations in Titan s atmosphere due to photochemical processes. The methane contained in the dense nitrogen atmosphere is decomposed by solar and thermal radiation, and its content may be replenished from methane lakes or from clathrates. 

Rate Nitrogen from air by PSA using carbon molecular sieve Nitrogen and methane using titanosilicate ETS-4... 

NITECH A cryogenic process for removing nitrogen from natural gas, mainly methane. The high-pressure gas is liquified by expansion and then fractionated. The essential feature is the use of an internal reflux condenser within the fractionating column. Developed by BCCK Engineering and demonstrated on a full-scale plant in Oregon in 1994. 

But the plots in Figure 2.9 are not horizontal. The deviation of a trace from the y = 1 line quantifies the extent to which a gas deviates from the ideal-gas equation the magnitude of the deviation depends on pressure. The deviations for ammonia and ethene are clearly greater than for nitrogen or methane we say that ammonia deviates from ideality more than does nitrogen. Notice how the deviations are worse at high pressure, leading to the empirical observation that a real gas behaves more like an ideal gas at lower pressures. 

Measurements have so far been made on mixtures of steam + hydrogen, nitrogen, argon, methane, carbon-dioxide, n-hexane, n-heptane, benzene and cyclohexane. The measurements cover the range 373 to 698 K at pressures from 0.1 MPa to saturation or 12.5 MPa. The only exception to this is steam + carbon dioxide for which the measurements extend up to 5.5 MPa. The accuracy of the measurements is around 2 percent. 

It might also be argued that ammonia and its derivatives are all petrochemicals since the hydrogen is derived from methane or natural gas. Many ammonia plants are near oil refineries. Urea even contains carbon and is considered an organic chemical. But because all these nitrogen... 

A VaporSep system was installed at a polyethylene plant to recover 290 lb of ethylene per hour (Ib/hr) from a gas stream consisting of 18% hydrogen, 22% nitrogen, 30% methane, and 30% ethylene. The capital costs for the system were 200,000. Based on an ethylene value of 300 per ton, the plant would save 370,000 per year using the VaporSep system to purify and recycle the ethylene (D205549, p. 5). 

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