Petroleum from methane

Dibenzoylmcthanc (l,3-diphcnyl-l,3-propanedione) [120-46-7] methane from petroleum ether or MeOH. [Beilstein 7 IV 2512.]... 

Relatively small amounts of methane, ethane, and propane also are produced as by-products from petroleum processes, but these usually are consumed as process or chemical feedstock fuel within the refineries. Some propane is recovered and marketed as LPG. 

Chlorination of Methane. Methane can be chlorinated thermally, photochemicaHy, or catalyticaHy. Thermal chlorination, the most difficult method, may be carried out in the absence of light or catalysts. It is a free-radical chain reaction limited by the presence of oxygen and other free-radical inhibitors. The first step in the reaction is the thermal dissociation of the chlorine molecules for which the activation energy is about 84 kj/mol (20 kcal/mol), which is 33 kJ (8 kcal) higher than for catalytic chlorination. This dissociation occurs sufficiendy rapidly in the 400 to 500°C temperature range. The chlorine atoms react with methane to form hydrogen chloride and a methyl radical. The methyl radical in turn reacts with a chlorine molecule to form methyl chloride and another chlorine atom that can continue the reaction. The methane raw material may be natural gas, coke oven gas, or gas from petroleum refining. 

A mixture of gaseous hydrocarbons, principally methane, which issues from the earth in certain areas, particularly near petroleum wells. Natural gas was the main source of carbon black until some 50 years ago when it was found more economic to use the gas for heating and produce carbon black from petroleum residues by the more efficient furnace process. 

Synthesis gas can easily be confused with the oxymoron synthetic natural gas, SNG. Both are sometimes called "syngas." But SNG is basically methane made from petroleum products, like naphtha or propane, or from coal. It s used as a substitute for or supplement to natural gas. 

The olefins—ethylene, propylene, and the butylenes—are derived from natural gas and petroleum. Methane is the major constituent in natural gas. The aromatics— benzene, toluene, and the xylenes— are derived from petroleum. About 90% by weight of the organic chemicals in the world comes from natural gas and petroleum. But actually only 3% of this crude oil and 6% of refinery output in the U.S. is processed into chemicals, with the rest going as various fuels. Although we are a small user of the petroleum industry, this 3-6% going to petrochemical feedstock is important to us ... 

Chemicals obtained from jjetroleum having four carbons are manufactured at a considerably lower scale than ethylene or propylene derivatives. Only five C4 compounds— butadiene, acetic acid, vinyl acetate, isobutylene, and methyl /-butyl ether (MTBE)— appear in the top 50. The manufacture of butadiene and isobutylene, as well as the separation of other C4 compounds from petroleum, is described in Chapter 8, Sections 3-5. Acetic acid was discussed as a derivative of ethylene in Chapter 9, Section 3 and is discussed as a derivative of methane in Chapter 12, Section 3. Vinyl acetate was discussed in Chapter 9, Section 4. A few important derivatives of C4 chemistiy will be briefly mentioned here as well as MTBE. 

Methanation, that is, the transformation of CO to methane222 270-272 [Eq. (3.1), reverse process], was developed in the 1950s as a purification method in ammonia synthesis. To prevent poisoning of the catalyst, even low levels of residual CO must be removed from hydrogen. This is done by methanation combined with the water-gas shift reaction.214,273,274 In the 1970s the oil crises spurred research efforts to develop methods for substitute natural-gas production from petroleum or coal via the methanation of synthesis gas. ... 

In 1946, the problem was demonstrating that the most fundamental assumptions did in fact hold. Initially, this meant obtaining measurements of the natural radiocarbon concentrations in living organics to see if it occurred in the amount expected and if the worldwide distribution of radiocarbon was essentially constant. An experiment was devised whereby biological methane gas derived from the sewage disposal plant at Baltimore, MD and petroleum methane from the Sun Oil Co. refinery were each enriched by a similar factor in a thermal diffusion column. It was assumed that the petroleum methane contained no because of its age in excess of many tens of millions of years whereas the biological methane contained about 17-18 dpm radiocarbon per g of carbon. The experiment was conducted, and the results confirmed the calculations (26). 

Reaction of Steam on Hydrocarbons. The catalytic interaction of steam and hydrocarbons has been used commercially on a large scale. The thermal cracking of hydrocarbons is an important part of petroleum refining and produces a large amount of hydrogen. The reaction of steam on methane from natural gas at about 1100 °C is... 

The following summarizes the yields estimated in this way for Paraho shale oil (in wt % ) olefins (ethylene, propylene, butadiene, 12.2 BTX, 23.5 fuels (including methane), 39.8 coke, 18.3 and hydrogen consumption (net), 0.9. No internal fuel requirements are reflected in these yields. The 36% yield to olefins and BTX could probably be increased significantly by further work, especially on steam pyrolysis to olefins. A bench mark is given in Ref. 8 for a hypothetical petrochemical refinery operated to obtain a 60% yield of BTX and olefins from petroleum. 

As stated above, some of the chemicals and compounds produced in a refinery are destined for further processing and as raw material feedstocks for the fast growing petrochemical industry. Such nonfuel uses of crude oil products are sometimes referred to as its nonenergy uses. Petroleum products and natural gas provide two of the basic starting points for this industry methane from natural gas, and naphtha and refinery gases. 

Gaseous fuels Principally natural gas (80% to 95% methane, the balance ethane, propane, and small quantities of other gases) also light hydrocarbons obtained from petroleum or coal treatment, acetylene, and hydrogen (the latter two are relatively expensive to produce). 

Methane from Carbides.—Another method of preparation is of interest and importance because of its connection with theories as to the formation of methane and other hydrocarbons in petroleum. With some metals carbon forms compounds which are very stable at high temperatures, and which have been artificially produced in the electric furnace (about 35O0°C.) by Moissan. These metallic carbon compounds, known as carbides, are, most of them, easily decomposed by water at ordinary temperatures, and when so decomposed they yield various members of the hydrocarbon group of compounds. A familiar example of this class of reactions is the one by which acetylene gas is made by the action of water on calcium carbide. The carbide of aluminium decomposes with water and yields methane according to the foUowing reaction ... 

Methane from Sodium Acetate.— Acetic acid, as we shall understand before we have proceeded far in our study, is a compound related to methane. When the sodium salt of this acid, i.e., sodium acetate, is heated it loses carbon dioxide, CO2, and methane is produced. In practice this heating is carried out in the presence of an alkali, e.g., calcium or sodium hydroxide, which absorbs the carbon dioxide, and in this way assists in the reaction. In order that we may not be troubled by the presence of water, dry materials are used, the sodium acetate being fused to obtain it free of water. When this dry sodium acetate is heated with a mixture of sodium and calcium hydroxides, known as soda-lime, a gas is produced which may be collected over water. The gas so made is methane and is identical with that found naturally as marsh gas and as a constituent of fire damp, natural gas, coal gas and petroleum. 

Petroleum chemicals fulfill two functions. They provide alternative and more economic routes to existing chemicals already made from other raw materials, and they lead to new industrial chemicals. The reactions of and outlets for chemicals more economically synthesized from petroleum have already been worked out, although perhaps not completely, in connection with the older routes. Those countries not favored with petroleum as an economic raw material have had to make use of alternative sources for these chemicals. In surveying the literature, it is, therefore, necessary to take account of the history of those petroleum chemicals which have been made from alternative sources. The reactions of methane are the same whether it is obtained from natural gas or as a by-product of the hydrogenation of coal or as a fraction in the liquefaction of coke oven gas depending on the source, the economics may be quite different. 

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