Ethane from natural gas

Ethylene is the cornerstone of the world s mam moth petrochemical industry and is produced in vast quantities In a typical year the amount of ethylene produced in the United States (5 x 10 ° lb) exceeds the combined weight of all of its people In one process ethane from natural gas is heated to bring about its dissociation into ethylene and hydrogen... 

Adsorption. Adsorption processes have been used to recover hydrocarbons that are heavier than ethane from natural gas. Although the adsorption process has appHcations for the recovery of pentane and heavier hydrocarbons from lean gas, the percentage recovery of LPG components in these plants usually is low compared to the normal recovery of LPG in modem turboexpander or oil-absorption plants. 

Separation of pure methane and ethane from natural gas... 

HYPERSORPTION. Process in w-hiclt activated car lion selectively absorbs the less-volatile components from a gaseous mix. while the more-volatile components pass on unaffected. Particularly applicable to separations of low-boiling mixtures such as hydrogen and methane, ethane from natural gas, ethylene from refinery gas, etc. 

Methane-based commercial production of ethylene via oxidative coupling has been investigated, but to date the lower per pass conversions required for acceptable ethylene selectivities combined with purified oxygen costs make this process noncompetitive with thermal cracking of ethane from natural gas liquids. 

From the above, the lighter the feedstock the poorer the thermal efficiency and therefore the higher the carbon emissions. This is counter to the move to increase ethylene production from ethane from natural gas operations. 

If all these proposals were to be implemented, then Malaysia is poised to become one of the major petrochemical producers in tlie region. There is a possibility that two ethylene crackers will be established. The one by Kellog-Thyssen will be based on naphtha fron crude oil, while the other by a Petronas joint-venture will be based on ethane from natural gas. Also Petronas, Neste Oy and Idemitsu Petrochemical will have a dehydrogenation facility in Kuantan, Pahang to produce propylene and isobutylene. The facilities described above will have the combined potential capacity to produce approximately 550,000 mt of ethylene,... 

In some markets availability of fossil feedstock like ethane from natural gas starts to become a limiting factor for the industry. In the USA some petroleum refineries (crackers) have been closed down due to expected shortage of feedstock. In other areas the reverse situation is at hand. For instance, in the Middle East the potential supply from flare gas is enormous. If not used for chemical production these volatiles are just flared and therefore the price is much lower than in Europe, USA or Japan. It is thus not surprising that a large part of the new investments in the petrochemical industry are in countries like Saudi Arabia, Kuwait and The Emirates. It is expected that this new capacity will mainly be directed towards the expanding economies in the East such as China and India. From the CO2 perspective it is also better that the flare gas is used to produce polymer instead of being directly burnt without producing any benefits. 

Olefins are produced primarily by thermal cracking of a hydrocarbon feedstock which takes place at low residence time in the presence of steam in the tubes of a furnace. In the United States, natural gas Hquids derived from natural gas processing, primarily ethane [74-84-0] and propane [74-98-6] have been the dominant feedstock for olefins plants, accounting for about 50 to 70% of ethylene production. Most of the remainder has been based on cracking naphtha or gas oil hydrocarbon streams which are derived from cmde oil. Naphtha is a hydrocarbon fraction boiling between 40 and 170°C, whereas the gas oil fraction bods between about 310 and 490°C. These feedstocks, which have been used primarily by producers with refinery affiliations, account for most of the remainder of olefins production. In addition a substantial amount of propylene and a small amount of ethylene ate recovered from waste gases produced in petroleum refineries. 

Natural gas Hquids represent a significant source of feedstocks for the production of important chemical building blocks that form the basis for many commercial and iadustrial products. Ethyleae (qv) is produced by steam-crackiag the ethane and propane fractions obtained from natural gas, and the butane fraction can be catalyticaHy dehydrogenated to yield 1,3-butadiene, a compound used ia the preparatioa of many polymers (see Butadiene). The / -butane fractioa can also be used as a feedstock ia the manufacture of MTBE. 

Condensable hydrocarbons are removed from natural gas by cooling the gas to a low temperature and then by washing it with a cold hydrocarbon hquid to absorb the condensables. The uncondensed gas (mainly methane with a small amount of ethane) is classified as natural gas. The condensable hydrocarbons (ethane and heavier hydrocarbons) are stripped from the solvent and are separated into two streams. The heavier stream, which largely contains propane with some ethane and butane, can be Hquefied and is marketed as Hquefied petroleum gas (LPG) (qv). The heavier fractions, which consist of and heavier hydrocarbons, are added to gasoline to control volatihty (see Gasoline and other motor fuels). 

The most important commercial use of ethane and propane is in the production of ethylene (qv) by way of high temperature (ca 1000 K) thermal cracking. In the United States, ca 60% of the ethylene is produced by thermal cracking of ethane or ethane/propane mixtures. Large ethylene plants have been built in Saudi Arabia, Iran, and England based on ethane recovery from natural gas in these locations. Ethane cracking units have been installed in AustraHa, Qatar, Romania, and Erance, among others. 

LPG is recovered from natural gas principally by one of four extraction methods turboexpander, absorption (qv), compression, and adsorption (qv). Selection of the process is dependent on the gas composition and the degree of recovery of ethane and LPG, particularly from large volumes of lean natural gas. 

Aliphatics. Methane, obtained from cmde oil or natural gas, or as a product from various conversion (cracking) processes, is an important source of raw materials for aliphatic petrochemicals (Fig. 10) (see Hydrocarbons). Ethane, also available from natural gas and cracking processes, is an important source of ethylene, which, in turn, provides more valuable routes to petrochemical products (Fig. 11). 

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. 

Probably the largest natural gas proeessing straddle plant in North Ameriea is BP-Amoeo s Empress, Alberta faeility. Here, EPBC (ethane, propane, butanes, and eondensate) are extraeted as liquids from natural gas before the gas is delivered to the TransCanada and Foothills (Saskatehewan) pipelines (Figure 8-5). The term straddle plant refers to the faet that the plant straddles the natural gas pipeline and extraets liquid eomponents before passing the natural gas further along the pipeline. 

Secondary raw materials, or intermediates, are obtained from natural gas and crude oils through different processing schemes. The intermediates may be light hydrocarbon compounds such as methane and ethane, or heavier hydrocarbon mixtures such as naphtha or gas oil. Both naphtha and gas oil are crude oil fractions with different boiling ranges. The properties of these intermediates are discussed in Chapter 2. 

Higher molecular weight hydrocarbons present in natural gases are important fuels as well as chemical feedstocks and are normally recovered as natural gas liquids. For example, ethane may be separated for use as a feedstock for steam cracking for the production of ethylene. Propane and butane are recovered from natural gas and sold as liquefied petroleum gas (LPG). Before natural gas is used it must be processed or treated to remove the impurities and to recover the heavier hydrocarbons (heavier than methane). The 1998 U.S. gas consumption was approximately 22.5 trillion ft. ... 

Natural gas and crude oils are the main sources for hydrocarbon intermediates or secondary raw materials for the production of petrochemicals. From natural gas, ethane and LPG are recovered for use as intermediates in the production of olefins and diolefms. Important chemicals such as methanol and ammonia are also based on methane via synthesis gas. On the other hand, refinery gases from different crude oil processing schemes are important sources for olefins and LPG. Crude oil distillates and residues are precursors for olefins and aromatics via cracking and reforming processes. This chapter reviews the properties of the different hydrocarbon intermediates—paraffins, olefins, diolefms, and aromatics. Petroleum fractions and residues as mixtures of different hydrocarbon classes and hydrocarbon derivatives are discussed separately at the end of the chapter. 

Ethane is an important paraffinic hydrocarbon intermediate for the production of olefins, especially ethylene. It is the second member of the alkanes and is mainly recovered from natural gas liquids. 

Propane is a more reactive paraffin than ethane and methane. This is due to the presence of two secondary hydrogens that could be easily substituted (Chapter 6). Propane is obtained from natural gas liquids or from refinery gas streams. Liquefied petroleum gas (LPG) is a mixture of propane and butane and is mainly used as a fuel. The heating value of propane is 2,300 Btu/ft. LPG is currently an important feedstock for the production of olefins for petrochemical use. 

The simplest paraffin (alkane) and the most widely used feedstock for producing ethylene is ethane. As mentioned earlier, ethane is obtained from natural gas liquids. Cracking ethane can be visualized as a free radical dehydrogenation reaction, where hydrogen is a coproduct ... 

A major use of propane recovered from natural gas is the production of light olefins by steam cracking processes. However, more chemicals can be obtained directly from propane by reaction with other reagents than from ethane. This may be attributed to the relatively higher reactivity of propane than ethane due to presence of two secondary hydrogens, which are easily substituted. 

In order to generate the starting material for a polymer that is used in water bottles, hydrogen is removed from the ethane in natural gas to produce ethene in the catalyzed reaction C,H6(g) H,(g) + C,ll4(g). Use the information in Appendix 2A to calculate the equilibrium constant for the reaction at 298 K. (a) If the reaction is begun by adding the catalyst to a flask containing C,H6 at 10.0 bar, what will be the partial pressure of the C,H4 at equilibrium (b) Identify three steps the manufacturer can take to increase the yield of product,... 

The principal source of alkanes is petroleum and natural gas, which contain only the more volatile alkanes. Therefore, low molecular weight alkanes, e.g. methane and small amounts of ethane, propane and other higher alkanes can be obtained directly from natural gas. Another fossil fuel, coal, is a potential second source of alkanes. Usually alkanes are obtained through refinement or hydrogenation of petroleum and coal. 

To limit the scope of this paper we may define natural gas liquids as liquid hydrocarbons normally recovered and recoverable from natural gas by physical processes only. Customarily these include propane, butane, and heavier hydrocarbons, but to a limited extent ethane is also recovered as a natural gas liquid. 

Ethylene is the basis for a large number of chemical reactions leading to styrene, acrylonitrile, Orion, and other synthetic fibers. Large scale production of ethylene for chemical raw material has recently been announced by one major oil company. Part will be made from natural gas ethane. 

The U.S. ethylene industry has been based primarily on the cracking of ethane and propane derived from natural gas. The quantities and liquid contents of U.S. natural gases have been such as to permit substantial quantities of these light hydrocarbons to be recovered for use as economically attractive ethylene feedstocks. In Europe and Japan, however, naphthas have been generally the available and preferred feeds to pyrolysis. 

United States. The U.S. ethylene industry has been based mainly on pyrolysis of light hydrocarbons, predominately ethane and propane recovered from natural gas. Essentially all the ethane recovered is used as pyrolysis feed, whereas only about one quarter of the propane is used for this purpose. The remainder is mostly consumed in the LPG market. 

Almost any naphthenic or parallflnic hydrocarbon heavier then methane can he steam-cracked to yield elhylene. The preferred feedstock in the United Slates has been ethane and/or propane recovered from natural gas. or from the volatile fractions of petroleum. However, because of longterm uncertainties pertaining to natural gas, many producers have been turning to heavier petroleum fractions, such as gas oils, as feedstock. The consumption of ethylene throughout the free world is estimated to be about 40 x 10 pounds per year,... 

Propane is a colorless, easily liquefied, gaseous hydrocarbon, the third member of the paraffin series following methane and ethane. The chemical formula for propane is CH3CH2CPI3. It is separated in large quantities from natural gas,... 

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