Natural gas and methane

The most common fuels were divided into three groups according to reactivity. The low-reactivity group included ammonia, methane, and natural gas hydrogen, acetylene, and ethylene oxide were classified as highly reactive. Those within these extremes, for example, ethane, ethylene, propane, propylene, butane, and isobutane, were classified as medium-reactivity fuels. 

Many detailed reaction mechanisms are available from the Internet. GRI-Mech (www.me.berkeley.edu/gri-mech/) is an optimized detailed chemical reaction mechanism developed for describing methane and natural gas flames and ignition. The last release is GRI-Mech 3.0, which was preceded by versions 1.2 and 2.11. The conditions for which GRI-Mech was optimized are roughly 1000-2500K, lOTorr to lOatm, and equivalence ratios from 0.1 to 5 for premixed systems. 

A.S. Pedersen, B. Larsen, Adsorption of methane and natural gas on six carbons, Rap. Riso-M-2781, Riso National Laboratory, Denmark, 1989. 

The two prevailing concepts on the origin and sources of natural gas and methane, its major constituent, are based on either biological or nonbiological reactions and mechanisms. Both address petroleum and, coincidentally, natural gas because the methane and other light hydrocarbons in natural gas are also constituents of most petroleum as produced. The mounting evidence for nonbiological methane and natural gas is briefly discussed below. 

Of particular note is that methane, and natural gas, if from great depths, should contain He from radioactive decay of the very dense uranium and thorium in the lower crust and mantle domains. This has been documented in most of the above instances. Natural gas reservoirs producing gas containing over 5%, sometimes as much as 10%, helium are long known, and they provide this purified gas for many industrial uses and lighter-than-air transportation craft. 

Following the invention of the high intensity electric arc several attempts have been made to convert methane and natural gas to acetylene. Unlike solids, gaseous reactants induce instability in the arc column by appreciable forced convection56. ... 

At present, the most known and widely used kinetic model for light hydrocarbon oxidation and combustion is GRI-Mech (Smith et al.), which has been developed since the 1990s by the Gas Research Institute. The project was aimed at the development of the detailed micro-chemical mechanism that can be used for simulations of natural gas ignition and combustion. Now the model is optimized for two fuels, methane and natural gas. Recommended temperature and pressure ranges are 1,000-2,500 K and 1.3 x 10 3-1 MPa, respectively the fuel-to-oxidant equivalence ratio in premixed compositions is 0.1-5. Although the scheme includes some reactions of C2-C3 hydrocarbons and oxygenates participating in methane (natural gas) combustion, it is not recommended to use GRI-Mech for simulations of their oxidation (combustion) as the main initial fuels, since the model is not optimized for these purposes. 

Scientists are now exploring other uses for methane and natural gas with the hope that they might eventually become the most important fuels used by humans. Methane has some advantages over petroleum and coal as a fuel. It... 

J. Liu and S. A. Barnett. Operation of anode-supported solid oxide fuel cells on methane and natural gas. Solid State Ionics 158, (2003) 11-16. 

Internal reforming of methane and natural gas in SOFCs has been demonstrated, both with and without partial pre-reforming [12, 28-30]. External pre-reforming of natural gas is used to... 

Gupta GK, Hecht ES, Zhu H, Dean AM, Kee RJ (2006) Gas-phase reactions of methane and natural-gas with air and steam in non-catalytic regions of a solid-oxide fuel cell. J Power... 

A mixture of the two reactants carbon monoxide and hydrogen is called synthesis gas and IS prepared by several processes The most widely used route to synthesis gas employs methane (from natural gas) and gives a 3 1 hydrogen to carbon monoxide ratio... 

Chemical Use. Both natural gas and natural gas Hquids are used as feedstocks in the chemical industry. The largest chemical use of methane is through its reactions with steam to produce mixtures of carbon monoxide and hydrogen (qv). This overall endothermic reaction is represented as... 

Chemical Processing. The use of oxygen in large-volume chemical and petrochemical manufacture is weU-estabHshed as a result of advantages 3) and 4). Most oxidation reactions are catalytic many begin with a feedstock initially made catalyticaHy from methane or natural gas. 

Hydrocarbon—Sulfur Process. The principal commercial hydrocarbon is methane from natural gas, although ethane, and olefins such as propylene (45,46), have also been used. 

Helium and Natural-Gas Systems Separation Helium is produced primarily by separation of hehum-rich natural gas. The hemim content of the natural gas from plants operated by the U.S. Bureau of Mines normally has varied from 1 to 2 percent while the nitrogen content of the natural gas has varied from 12 to 80 percent. The remainder of the natural gas is methane, ethane, and heavier hydrocarbons. 

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. 

This reaction is of great technological interest in the area of solid oxide fuel cells (SOFC) since it is catalyzed by the Ni surface of the Ni-stabilized Zr02 cermet used as the anode material in power-producing SOFC units.60,61 The ability of SOFC units to reform methane "internally", i.e. in the anode compartment, permits the direct use of methane or natural gas as the fuel, without a separate external reformer, and thus constitutes a significant advantage of SOFC in relation to low temperature fuel cells. 

The increase in the price of oil and natural gas motivates the chemical industry to develop processes that use alternative raw materials and to develop efficient and economical processes for liquid fuels synthesis from coal and natural gas. An innovative promising approach for producing gasoline from methane is presented in [5]. Other important tasks are development of efficient methods for producing liquid fuels from unconventional sources such as oil shale, tar sands, and deep-sea methane hydrates. 

This technology uses C02 as a feed gas for the production of carbon products with Etogas methanation plant (Figure 20), which are reactor systems for conversion of H2 and C02 to methane (synthetic natural gas). The produced gas is DVGW- and DIN-compliant synthetic natural gas and can be used directly, e.g., as a fuel for a CNG vehicle. 

Selectivity for C02 it represents the C02 uptake ratio to the adsorption of any other gas (typically nitrogen for post-combustion capture, and methane for natural gas). It is an essential evaluation criterion, and affects the purity of the adsorbed gas, which will significantly influence the sequestration of C02. The simplest method to estimate the selectivity factor is to use single-component adsorption isotherms of C02 and nitrogen. 

Ammonia is synthesised from its elements nitrogen and hydrogen. The nitrogen is obtained by the fractional distillation of liquid air. The hydrogen is obtained by the reaction of methane (from natural gas) with steam. 

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