Butane vs Methane - Difference and Comparison | Diffen Butane vs. Methane Butane and methane are hydrocarbons from the same chemical family compounds known as alkanes. They are components of natural gas and extraction of oil.

Comparison chart Butane versus Methane comparison chart Butane 2.48 kg/m3, gas (15 °C, 1 atm) 600 kg/m3, liquid (0 °C, 1 atm) 0.717 kg/m3, gas 415 kg/m3 liquid Melting point -182.5 °C, 91 K, -297 °F Boiling point -161.6 °C, 112 K, -259 °F Solubility in water 6.1 mg/100 ml (20 °C) 35 mg/L (17 °C) Methanol, chloromethane, formic acid, formaldehyde, silane Structure and properties Phase behaviour Solid, liquid, gas Phase behaviour Solid, liquid, gas Spectral data Butane is used in refrigeration, cigarette lighters, heating as LPG or liquefied petroleum gas. Methane is an energy source used for heating purposes. Harmful effects Butane can cause asphyxiation and ventricular fibrillation. Methane is a potent greenhouse gas. It can form explosive mixtures with air.

Sources Natural gas fields, biogas production, atmospheric methane, extra terrestrial methane. Contents: Butane vs Methane 7 References Chemical formula and Molecular structure of methane vs butane Butane is C4H10 while methane has the chemical formula – CH4. Thus there are four hydrogen atoms in a methane molecule while there ten hydrogen atoms in a butane molecule. The molecule of methane forms a tetrahedral structure while butane is a linear structure. Methane molecule - 3D rendering Methane molecule - structural formula determined using microwave spectroscopy Butane molecule - 3-dimensional rendering Butane molecule - chemical formula Chemical Reactions of methane and butane Butane reacts with oxygen to form carbon dioxide and water vapor. Under conditions of limited oxygen, butane can form carbon monoxide or charred carbon. It reacts with chlorine to give chlorobutanes and other derivatives. Methane undergoes combustion to give formaldehyde, carbon monoxide and finally carbon dioxide and water vapor. The process is known as pyrolysis. Ease in Handling Both methane and butane are odorless gases at room temperatures. Butane can be easily liquefied hence it is sold as fuel for camping and cooking.

It is mixed with propane and other hydrocarbons to from LPG which is commercially used for heating and cooking purposes. Methane is difficult to transport and is transported by pipelines and LNG carriers. Unlike methane which is a stubborn gas in normal pressure and temperature, butane turns into a liquid when compressed. This property is attributed to the weak central carbon atom bonds. As soon as this liquefied gas comes in contact with air, it reacts with ignition source and become inflammable. Isomers Butane exhibits structural isomerism unlike methane and has two isomers, n-butane and iso-butane. Methane does not exhibit isomerism. Uses of methane vs butane Butane is used in deodorants, cigarette lighters, cooking and heating gas cylinders, propellant in aerosol sprays and refrigerants etc. Methane also known as marsh or swamp gas is used for firing electrical generation stations, power automobiles etc. Sources Methane is found in wetlands and oceans, atmosphere, human sources like burning fuel, raising livestock, fermentation of organic matter etc. Butane can be obtained as a byproduct during extraction of crude oil and is a component of natural gas .

References Oil and Gas Industry Overview Next Page Crude Oil and Natural Gas: From Source to Final Products Crude oil and natural gas are mixtures of hydrocarbons-chemical molecules that contain only hydrogen and carbon. Crude oil is a liquid both underground and at normal surface conditions. Natural gas is a vapor at normal surface conditions; underground, it can exist either as a vapor or something like a bottle of carbonated soda-"in solution" with crude oil until the pressure is reduced. The term "petroleum" collectively refers to crude oil, natural gas and solid hydrocarbon mixtures like tar and asphalt. In addition to hydrocarbons, petroleum may contain impurities such as water, sulfur compounds, oxygen, nitrogen, carbon dioxide and traces of metals. Chemistry of Hydrocarbons The smallest unit of a hydrocarbon compound is a molecule consisting of hydrogen and carbon atoms. The physical properties of a hydrocarbon mixture - whether it exists as a solid, liquid or gas under a given set of conditions, how much energy it contains, what products can be derived from it and so on - are determined by the numbers and configurations of atoms contained within each of its molecules, and how much these molecules weigh. The simplest hydrocarbon molecule is methane.

It is the essential ingredient of natural gas, and the source of the "blue flame" that we see when we turn on a gas stove or furnace (Figure 7). Methane consists of one carbon (C) atom and four hydrogen (H) atoms. Thus, its chemical formula is CH4 or, in abbreviated form, C1. Figure 7: The familiar blue flame that characterizes the combustion of methane, the key component of natural gas. The molecular weight of a molecule is equal to the total weight of its constituent atoms. Hydrogen, the smallest atom, has an atomic weight of 1 by definition. Carbon has an atomic weight of 12. Thus, we can determine the molecular weight of methane as follows: Total atomic weight of carbon atoms: 1 x 12 = 12 Total atomic weight of hydrogen atoms: 4 x 1 = 4 Total molecular weight = 12 + 4 = 16 Figure 8 shows the names, chemical formulas, molecular weights, structures and key physical properties of the "lighter" hydrocarbons C1 through C4. Note that: The more atoms a molecule contains, the heavier it is.

The molecular weight of ethane (C2) is 30, while that of propane (C3) is 44 and that of butane (C4) is 58. The heavier a molecule, the more likely it is to exist as a liquid at normal surface conditions. This is based on its higher boiling point (i.e., the temperature above which it changes from a liquid to a gas at atmospheric pressure). It is also more likely to have a higher energy content or heating value per unit volume. Methane, ethane and propane each have a single molecular configuration. Butane (C4H10), however, shows two possible arrangements (normal butane and iso-butane), and each arrangement has unique physical properties. Because a simple, heavy hydrocarbon molecule can contain as many as 66 or more carbon atoms, the variety of molecular arrangements that can be present in a mixture and therefore, the range of physical characteristics is immense. Figure 8: Atomic structure, chemical name and potential uses of the hydrocarbon molecules methane (C1) through normal and iso-butane (n-C4 and i-C4).

Natural gas mixtures fall into two general categories: dry or lean natural gas has high concentrations of methane and ethane (typically 95 percent or more), while wet, or rich, gases have higher concentrations of propane, butane and the intermediate-weight hydrocarbons pentane (C5) through heptane (C7). As the proportions of heavier molecules in a hydrocarbon mixture increase, it is more likely to exist as a liquid at atmospheric conditions. Origins of Crude Oil and Natural Gas Naturally occurring hydrocarbons come from the decomposed remains of ancient plants and animals. Through a sequence of geologic events that occurred over millions of years, organic material was deposited on the Earth's surface and then transported to depressions or basins, where it accumulated and gradually became buried at great depths under layers and layers of sediments. There, in what geologists refer to as source rocks, it was subjected to much higher pressures and temperatures. Over time, and through a series of intermediate chemical reactions, some of this material eventually turned into petroleum. In general, the deeper a rock formation is located in the Earth's crust, the higher its temperature will be.

Thus, the type of petroleum that formed through these processes depended largely on the depth of the source rocks. In relatively shallow source rocks, where temperatures ranged from about 60 to 80°C [140 -176°F], the organic matter was converted into heavy oil. At lower depths and higher temperatures, from about 80°C to 175°C [176°F to 347°F], the heavier, long-chain organic molecules began to break up into shorter molecules and form medium and light oil. Where temperatures exceeded 175°C [347°F], the molecules became even shorter and lighter, with more and more matter transformed to rich gas until, by the time it had reached 600°F [315°C], all of it had been transformed to dry gas (methane). Figure 9 shows the wide diversity that exists among petroleum fluids discovered worldwide. Figure 9: Selection of petroleum samples ranging from a heavy black oil on the right to a light condensate on the left. Petroleum Migration and Accumulation The source rocks in which petroleum formed millions of years ago are not the same rocks in which it is found today.

Rather, oil and gas, being lighter than the water normally contained in rock formations, moved upward by gravity forces from the source beds along permeable migration paths. Eventually, it accumulated in reservoirs contained within geologic traps, surrounded by impermeable cap rocks or seals that keep it from traveling any farther (Figure 10). Figure 10: Cross section showing source rocks, migration paths and reservoirs in a sedimentary basin similar to the North Sea basin. After oil and gas form in the source rocks, gravity causes them to migrate upward until they are trapped in a reservoir waiting for discovery. Petroleum Reservoirs The term "reservoir" brings to mind the image of a large pond or lake, so it is natural to hear the term petroleum reservoir and picture a huge underground "pool" of oil. In reality, a petroleum reservoir is a porous, permeable rock formation, in which oil and gas are contained in the empty spaces between the rock grains. These spaces are interconnected, thereby forming channels or conduits through which fluids can flow to a well, and from there to the surface.

Separation and Treatment of Produced Oil and Gas The fluid that comes out of a typical oil well is actually a combination of crude oil and natural gas, often mixed with water, non-hydrocarbon gases and other impurities. That is the reason why the volume of crude oil and natural gas is so different from the reservoir conditions and surface conditions, as shown in Figure 11. Figure 11: Hydrocarbon fluids change state as they travel from the reservoir to the surface. The first step in processing this fluid is to route it to centralized surface handling facilities, where carefully designed vessels are used to separate the oil, water and gas into individual streams. The water is pumped back into the reservoir or otherwise disposed of in an environmentally friendly manner. The oil is metered and stored in tanks to await pipeline or tanker transport to the point of sale, and the gas is treated or conditioned to remove water vapor and other impurities and processed to recover gas liquids before being metered and sold. Figure 12 shows the representative compositions of various produced fluids after separation at the surface, including a crude oil with associated gas, a wet (rich) gas and a dry (lean) gas. Figure 12: Representative compositions of various produced fluids after separation at the surface.

Note that C7+ refers to the composition of C7 plus all the heavier hydrocarbons. Gas Handling and Processing If the treated gas is dry or lean (i.e., contains mostly methane), it may either be compressed and sent directly to its point of sale through high-pressure pipelines, or it may be turned into liquefied natural gas (LNG) by cooling it to temperatures as low as -160ºC [-258ºF]. LNG occupies only about 1/625 of the volume of dry gas, allowing it to be transported to distant markets in specially designed ships. If the gas is wet or rich (i.e., has substantial amounts of ethane or heavier hydrocarbons), one post-treatment option might be to send it to a gas processing plant. There, it may be cooled to around -150ºF [-101ºC], causing these hydrocarbons to condense to NGL (natural gas liquids). The NGL is then sold to a refinery or petrochemical plant. If sufficient NGL is available, it may be economical to separate it further into its constituent hydrocarbons.

This involves a process called fractionation in a series of columns, where the NGL is sequentially warmed to higher temperatures, causing the individual hydrocarbons-ethane first, then propane, then butanes-to boil off and then condense. Propane, butanes and their mixtures are referred to as liquefied petroleum gases (LPGs).This leaves a residual, Natural Gasoline, which can be stored at atmospheric conditions (Figure 13). Natural gas, LNG, NGL, LPGs and the hydrocarbons that come from them all have individual markets, and all of them are in their final form to be used as fuels or for manufacturing petrochemicals. Figure 13: Rich gas is separated by gas processing into dry gas and NGLs. The NGLs may be sold to a refinery or petrochemical complex, or separated by fractionation into individual hydrocarbon liquids. Crude Oil Refining Except for a few special power generation applications, most crude oils are not suitable for use as finished products. In nearly all cases, they must be refined to satisfy specific markets. Figure 14 illustrates, from left to right, the basic processes involved in refining crude oil.

Initially, products may range from light gasoline vapors and LPG to heavy residuals ("residuum"). Depending on market demand, these first "cuts" will proceed to more complex processing into final product blends (e.g., seasonal transportation fuels, heating fuels and special products like lubricating oils and asphalt). The refiner's ultimate goal is to maximize the crack spread-the per-unit difference between the product revenue and the cost of the crude oil. If the products sell for $52 per barrel, for example, and the cost of crude is $47 per barrel, then the crack spread is ($52-$47), or $5 per barrel. Figure 14: Simplified schematic of a refinery showing how a crude oil turned into an initial "cut" of refined products. Petrochemicals Natural gas, natural gas liquids (including LPG) and the various refinery cuts may also be used as raw materials or feedstocks for manufacturing petrochemicals. For example, methane can be used to make ammonia for fertilizer, and ethane can be used to make ethylene, the first step in making plastics. Table 1 lists some of the major categories of products that come from petrochemicals.

Consider which of these products you use daily, and what would you do or what would be your alternatives if these products did not exist. Some Major Categories of Petrochemical Products Plastics Patent WO2011053745A1 - Process for the conversion of propane and butane to aromatic hydrocarbons - Google Patents Process for the conversion of propane and butane to aromatic hydrocarbons WO 2011053745 A1 Abstract A process for the conversion of propane and/or butane into aromatics which comprises first reacting a propane and/or butane feed in the presence of an aromatization catalyst under reaction conditions which maximize the conversion of propane and/or butane into first stage aromatic reaction products, separating ethane produced in the first stage reaction from the first stage aromatic reaction products, reacting ethane in the presence of an aromatization catalyst under reaction conditions which maximize the conversion of ethane into second stage aromatic reaction products, and optionally separating ethane from the second stage aromatic reaction products. Claims (OCR text may contain errors) C L A I M S 1.

A process for the conversion of butane and/or propane into aromatics which comprises first reacting a butane and/or propane feed in the presence of an aromatization catalyst under first stage reaction conditions which maximize the conversion of propane and/or butane into first stage aromatic reaction products, separating ethane produced in the first stage aromatic reaction from the first aromatic reaction products, reacting the ethane in presence of an aromatization catalyst under second stage reaction conditions which maximize the conversion of ethane into second stage aromatic reaction products, and optionally separating ethane from the second stage aromatic reaction products. 2. The process of claim 1 wherein the aromatization reaction is carried out at a temperature of from 400 to 700�C. 3. The process of claims 1 and 2 wherein the first stage reaction conditions comprise a temperature of from 400 to 650�C, preferably from 420 to 650�C. 4. The process of claims 1 to 3 wherein the second stage reaction conditions comprise a temperature of from 450 to 680�C, preferably from 450 to 660�C. 5.

The process of claims 1 to 4 wherein the first stage reaction products are produced in at least two reactors aligned in parallel. 6. The process of claims 1 to 5 wherein the second stage reaction products are produced in at least two reactors aligned in parallel. 7. The process of claims 1 to 6 wherein fuel gas is also produced in either or both of the first and second stages and is separated from the aromatic reaction products and ethane. 8. The process of claim 1 wherein at least part of the ethane produced in the first stage aromatization reaction is mixed with the propane and/or butane feed to the first stage aromatization reactor. Description (OCR text may contain errors) PROCESS FOR THE CONVERSION OF PROPANE AND BUTANE TO AROMATIC HYDROCARBONS Field of the Invention The present invention relates to a process for producing aromatic hydrocarbons from propane and/or butane. More specifically, the invention relates to a two stage process for increasing the production of benzene from a mixture of propane and butane in a dehydroaromatization process.

Background of the Invention There is a projected global shortage for benzene which is needed in the manufacture of key petrochemicals such as styrene, phenol, nylon and polyurethanes , among others. Generally, benzene and other aromatic hydrocarbons are obtained by separating a feedstock fraction which is rich in aromatic compounds, such as reformate produced through a catalytic reforming process and pyrolysis gasolines produced through a naphtha cracking process, from non-aromatic hydrocarbons using a solvent extraction process. To meet this projected supply shortage, numerous catalysts and processes for on-purpose production of aromatics (including benzene) from alkanes containing six or less carbon atoms per molecule have been investigated. These catalysts are usually bifunct ional , containing a zeolite or molecular sieve material to provide acidity and one or more metals such as Pt, Ga, Zn, Mo, etc. to provide dehydrogenat ion activity. For example, U.S. Patent 4,350,835 describes a process for converting ethane-containing gaseous feeds to aromatics using a crystalline zeolite catalyst of the ZSM-5-type family containing a minor amount of Ga .

As another example, U.S. Patent 7,186,871 describes aromatization of Ci-C4 alkanes using a catalyst containing Pt and ZSM-5. Most lower alkane dehydroaromatization processes carry out the reaction in one step. For example, EP0147111 describes an aromatization process wherein a C3-C4 feed is mixed with ethane and all are reacted together in a single reactor. A minority of these processes involves two separate steps or stages. For example, US 3,827,968 describes a process which involves oligomerization followed by aromatization. US 4,554,393 and US 4,861,932 describe two- step processes for propane involving dehydrogenation followed by aromatization. None of these examples mention a two-stage process in which lower alkane aromatization takes place in both stages. The aromatization of propane and butane results in the production of a significant amount of ethane and methane byproducts by hydrogenolysis . Ethane is more difficult to convert to benzene than propane or butane because it is less reactive.

Generally, the byproduct ethane is not subjected to further reaction, which leads to a lower yield of aromatics from the propane and/or butane feed. It would be desirable if a significant level of conversion of the byproduct ethane to aromatics could be achieved. It would be advantageous to provide a light alkane dehydroaromatization process wherein (a) the conversion of each component of a mixed alkane feed can be optimized, (b) the ultimate yield of benzene is greater than that of any other single aromatic product, and (c) the generation of undesired methane by-product is minimized. Summary of the Invention The above problem is resolved by designing a two-stage process as described below.

The present invention provides a process for the conversion of propane and/or butane into aromatics which comprises first reacting a propane and/or butane feed in the presence of an aromatization catalyst under first stage reaction conditions which maximize the conversion of the propane and/or butane into first stage aromatic reaction products, separating the first aromatic reaction products from the ethane which is produced in the first stage reaction, reacting ethane in the presence of an aromatization catalyst under second stage reaction conditions which maximize the conversion of ethane into second stage aromatic reaction products, and optionally separating any unreacted ethane from the second aromatic reaction products. Fuel gas, which includes primarily methane and hydrogen, may also be produced in either or both of the first and second stages. The fuel gas may be separated from the aromatic reaction products in either or both of the stages. Thus, fuel gas may be an additional product of the process of this invention. Brief Description of the Drawings Fig. 1 is a schematic flow diagram which illustrates the process scheme for producing aromatics (benzene and higher aromatics) from a propane and butane feed containing at least using a one reactor-regenerator stage process. Fig.

2 is a schematic flow diagram for producing aromatics (benzene and higher aromatics) from propane and butane feed using a two stage reactor-regenerator system. Fig. 3 is a schematic flow diagram for producing aromatics (benzene and higher aromatics) using a two stage reactor-regenerator system from a propane and butane feed with ethane co-fed from the recycle stream to the first stage aromatization reactor. Detailed Description of the Invention The present invention is a process for producing aromatic hydrocarbons which comprises bringing into contact a hydrocarbon feedstock containing propane and/or butane, preferably at least 20%wt propane, and possibly other hydrocarbons such as ethane, and a catalyst composition suitable for promoting the reaction of such hydrocarbons to aromatic hydrocarbons, such as benzene, at a temperature of from about 400 to about 700�C and a pressure of from about 0.01 to about 1.0 Mpa absolute. The gas hourly space velocity (GHSV) per hour may range from about 300 to about 6000.

These conditions are used in each of the stages but the conditions in the stages may be the same or different. The conditions may be optimized for the conversion of propane and butane in the first stage and ethane in the second stage. In the first stage, the reaction temperature preferably ranges from about 400 to about 650�C, most preferably from about 420 to about 650�C, and in the second stage, the reaction temperature preferably ranges from about 450 to about 680�C, most preferably from about 450 to about 660�C. The primary desired products of the process of this invention are benzene, toluene and xylene (BTX) . In an embodiment, the first stage reaction conditions may be optimized for the conversion of propane and butane to aromatics. In the second stage reaction conditions may be optimized for the conversion of ethane to aromatics. The first stage and second stage reactors may be operated under similar conditions.

When either reactor is run at higher temperatures, i.e., above about 630 - 650�C, more fuel gas and less aromatics are produced even though the net feed conversion per pass for that stage may be higher. Therefore it is better to run at lower temperature and convert less feed in each pass of each stage in order to produce more aromatics in total. Operating in the preferred range helps to maximize aromatics production by minimizing fuel gas production. The use of higher temperatures may maximize the production of fuel gas. Fuel gas may be an additional product of the process of the present invention. Fuel gas includes primarily methane and hydrogen which are produced along with the aromatics. Fuel gas may be used for power and/or steam generation. The hydrogen in the fuel gas may be separated and used for refinery or chemical reactions that require hydrogen, including the hydrodealkylation of toluene and/or xylene as discussed below. It is possible to carry out this process in batch mode using separate reactors for each stage or using the same reactor for each stage but it is highly preferred that it be carried out in continuous mode in separate reactors. Each stage may be carried out in a single reactor or in two or more reactors aligned in parallel.

Preferably, at least two reactors are used in each stage so that one reactor may be in use for aromatization while the other reactor is offline so the catalyst may be regenerated. The aromatization reactor system may be a fluidized bed, moving bed or a cyclic fixed bed design. The cyclic fixed bed design is preferred for use in this invention. The hydrocarbons in the feedstock may be comprised of propane and/or butane, preferably at least about 20 %wt of propane. In one embodiment, the feedstock is from about 30 to about 90 wt% propane and from about 10 to about 50 wt% butane. The feed may contain small amounts of C2-C4 olefins, preferably no more than 5 to 10 weight percent. Too much olefin may cause an unacceptable amount of coking and deactivation of the catalyst. A mixed propane/butane feed stream may be derived from, for example, an ethane/propane/butane-rich stream derived from natural gas, refinery or petrochemical streams including waste streams.

Examples of potentially suitable feed streams include (but are not limited to) residual propane and butane from natural gas (methane) purification, pure propane and butane streams (also known as Liquified Petroleum Gas, LPG) co-produced at a liquefied natural gas (LNG) site, C3-C4 streams from associated gases co-produced with crude oil production (which are usually too small to justify building a LNG plant but may be sufficient for a chemical plant), unreacted "waste" streams from steam crackers, and the C1-C4 byproduct stream from naphtha reformers (the latter two are of low value in some markets such as the Middle East) . Usually natural gas, comprising predominantly methane, enters an LNG plant at elevated pressures and is pre-treated to produce a purified feed stock suitable for liquefaction at cryogenic temperatures. Ethane, propane, butane and other gases are separated from the methane. The purified gas (methane) is processed through a plurality of cooling stages using heat exchangers to progressively reduce its temperature until liquefaction is achieved. The separated gases may be used as the feed stream of the present invention.

The byproduct streams produced by the process of the present invention may have to be cooled for storage or recycle and the cooling may be carried out using the heat exchangers used for the cooling of the purified methane gas. Any one of a variety of catalysts may be used to promote the reaction of propane and butane to aromatic hydrocarbons. One such catalyst is described in U.S. 4,899,006 which is herein incorporated by reference in its entirety. The catalyst composition described therein comprises an aluminosilicate having gallium deposited thereon and/or an aluminosilicate in which cations have been exchanged with gallium ions. The molar ratio of silica to alumina is at least 5:1. Another catalyst which may be used in the process of the present invention is described in EP 0 244 162. This catalyst comprises the catalyst described in the preceding paragraph and a Group VIII metal selected from rhodium and platinum. The aluminosilicates are said to preferably be MFI or MEL type structures and may be ZSM-5, ZSM-8, ZSM-11, ZSM- 12 or ZSM-35.

Other catalysts which may be used in the process of the present invention are described in U.S. 7,186,871 and U.S. 7,186,872, both of which are herein incorporated by reference in their entirety. The first of these patents describes a platinum containing ZSM-5 crystalline zeolite synthesized by preparing the zeolite containing the aluminum and silicon in the framework, depositing platinum on the zeolite and calcining the zeolite. The second patent describes such a catalyst which contains gallium in the framework and is essentially aluminum-free. It is preferred that the catalyst be comprised of a zeolite, a noble metal of the platinum family to promote the dehydrogenation reaction, and a second inert or less active metal which will attenuate the tendency of the noble metal to catalyze hydrogenolysis of the higher hydrocarbons in the feed to methane and/or ethane. Attenuating metals which can be used include those described below. Additional catalysts which may be used in the process of the present invention include those described in U.S. 5,227,557, hereby incorporated by reference in its entirety.

These catalysts contain an MFI zeolite plus at least one noble metal from the platinum family and at least one additional metal chosen from the group consisting of tin, germanium, lead, and indium. One preferred catalyst for use in this invention is described in U.S. Application No. 12/371787, filed February 16, 2009 entitled "Process for the Conversion of Ethane to Aromatic Hydrocarbons." This application is hereby incorporated by reference in its entirety.

This application describes a catalyst comprising: (1) 0.005 to 0.1 %wt (% by weight) platinum, based on the metal, preferably 0.01 to 0.05 %wt, (2) an amount of an attenuating metal selected from the group consisting of tin, lead, and germanium which is preferably not more than 0.2 %wt of the catalyst, based on the metal and wherein the amount of platinum may be no more than 0.02 %wt more than the amount of the attenuating metal; (3) 10 to 99.9 %wt of an aluminosilicate, preferably a zeolite, based on the aluminosilicate, preferably 30 to 99.9 %wt, preferably selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-23, or ZSM-35, preferably converted to the H+ form, preferably having a S1O2/AI2O3 molar ratio of from 20:1 to 80:1, and (4) a binder, preferably selected from silica,

 alumina and mixtures thereof.

Another preferred catalyst for use in this invention is described in U.S. Provisional Application No. 61/029939, filed February 20, 2008 entitled "Process for the Conversion of Ethane to Aromatic Hydrocarbons." This application is hereby incorporated by reference in its entirety.

The application describes a catalyst comprising: (1) 0.005 to 0.1 %wt (% by weight) platinum, based on the metal, preferably 0.01 to 0.06 %wt, most preferably 0.01 to 0.05 %wt, (2) an amount of iron which is equal to or greater than the amount of the platinum but not more than 0.50 %wt of the catalyst, preferably not more than 0.20 %wt of the catalyst, most preferably not more than 0.10 %wt of the catalyst, based on the metal; (3) 10 to 99.9 %wt of an aluminosilicate, preferably a zeolite, based on the aluminosilicate, preferably 30 to 99.9 %wt, preferably selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-23, or ZSM-35, preferably converted to the H+ form, preferably having a Si02/Al2C>3 molar ratio of from 20:1 to 80

:1, and (4) a binder, preferably selected from silica, alumina and mixtures thereof .

Another preferred catalyst for use in this invention is described in U.S. Application No. 12/371803, filed February 16, 2009 entitled "Process for the Conversion of Ethane to Aromatic Hydrocarbons." This application is hereby incorporated by reference in its entirety.

This application describes a catalyst comprising: (1) 0.005 to 0.1 wt% (% by weight) platinum, based on the metal, preferably 0.01 to 0.05% wt, most preferably 0.02 to 0.05% wt, (2) an amount of gallium which is equal to or greater than the amount of the platinum, preferably no more than 1 wt%, most preferably no more than 0.5 wt%, based on the metal; (3) 10 to 99.9 wt% of an aluminosilicate, preferably a zeolite, based on the aluminosilicate, preferably 30 to 99.9 wt%, preferably selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-23, or ZSM-35, preferably converted to the H+ form, preferably having a Si02/Al2C>3 molar ratio of from 20:1 to 80:1, and (4) a binder, preferably selected from silica, alumina and mixtures thereof.

One of the undesirable products of the aromatization reaction is coke which may deactivate the catalyst. While catalysts and operating conditions and reactors are chosen to minimize the production of coke, it is usually necessary to regenerate the catalyst at some time during its useful life. Regeneration may increase the useful life of the catalyst. Regeneration of coked catalysts has been practiced commercially for decades and various regeneration methods are known to those skilled in the art. The regeneration of the catalyst may be carried out in the aromatization reactor or in a separate regeneration vessel or reactor. For example, the catalyst may be regenerated by burning the coke at high temperature in the presence of an oxygen-containing gas as described in US Patent No. 4,795,845 which is herein incorporated by reference in its entirety. Regeneration with air and nitrogen is shown in the examples of US Patent No. 4,613,716 which is herein incorporated by reference in its entirety. Another possible method involves air calcination, hydrogen reduction, and treatment with sulfur or a sulfurization material. Platinum catalysts have been used to assist the combustion of coke deposited on such catalysts.

The preferred regeneration temperature range for use herein is from about 450 to about 788�C. The preferred temperature range for regeneration in the first stage is from about 470 to about 788�C. The preferred temperature range for regeneration in the second stage is from about 500 to about 788�C. The unreacted methane and byproduct hydrocarbons may be used in other steps, stored and/or recycled. It may be necessary to cool these byproducts to liquefy them. When the propane and butane originate from an LNG plant as a result of the purification of the natural gas, at least some of these byproducts may be cooled and liquefied using the heat exchangers used to liquefy the purified natural gas (methane) . The toluene and xylene may be converted into benzene by hydrodealkylation . The hydrodealkylation reaction involves the reaction of toluene, xylenes, ethylbenzene, and higher aromatics with hydrogen to strip alkyl groups from the aromatic ring to produce additional benzene and light ends including methane and ethane which are separated from the benzene.

This step substantially increases the overall yield of benzene and thus is highly advantageous. Both thermal and catalytic hydrodealkylation processes are known in the art. Methods for hydrodealkylation are described in US Published Patent Application No. 2009/0156870 which is herein incorporated by reference in its entirety. The integrated process of this invention may also include the reaction of benzene with propylene to produce cumene which may in turn be converted into phenol and/or acetone. The propylene may be produced separately in a propane dehydrogenation unit or may come from olefin cracker process vent streams or other sources. Methods for the reaction of benzene with propylene to produce cumene are described in US Published Patent Application No. 2009/0156870 which is herein incorporated by reference in its entirety. The integrated process of this invention may also include the reaction of benzene with olefins such as ethylene. The ethylene may be produced separately in an ethane dehydrogenation unit or may come from olefin cracker process vent streams or other sources. Ethylbenzene is an organic chemical compound which is an aromatic hydrocarbon.

Its major use is in the petrochemical industry as an intermediate compound for the production of styrene, which in turn is used for making polystyrene, a commonly used plastic material. Methods for the reaction of benzene with ethylene to produce ethylbenzene are described in US Published Patent Application No. 2009/0156870 which is herein incorporated by reference in its entirety. Styrene may then be produced by dehydrogenating the ethylbenzene. One process for producing styrene is described in U.S. Patent No. 4,857,498, which is herein incorporated by reference in its entirety. Another process for producing styrene is described in U.S. Pat. No. 7,276,636, which is herein incorporated by reference in its entirety. EXAMPLES The following examples are provided for illustrative purposes only and are not intended to limit the scope of the invention. Example 1 In this example the results of laboratory tests are used to represent a one-stage aromatization process vs. a two- stage process utilizing the same catalyst in each stage.

The lower alkane feedstock of this example consists of 43.1%wt propane and 56.9%wt n-butane, and the temperature of the second stage is higher than the temperature of the first stage . Catalyst A was made on 1.6 mm diameter cylindrical extrudate particles containing 80%wt of zeolite ZSM-5 CBV 2314 powder (23:1 molar S1O2/AI2O3 ratio, available from Zeolyst International) and 20%wt alumina binder. The extrudate samples were calcined in air up to 650�C to remove residual moisture prior to use in catalyst preparation. The target metal loadings for Catalyst A were 0.025%w Pt and 0.09%wt Ga.

Metals were deposited on 25-100 gram samples of the above ZSM-5/alumina extrudate by first combining appropriate amounts of stock aqueous solutions of tetraammine platinum nitrate and gallium(III) nitrate, diluting this mixture with deionized water to a volume just sufficient to fill the pores of the extrudate, and impregnating the extrudate with this solution at room temperature and atmospheric pressure. Impregnated samples were aged at room temperature for 2-3 hours and then dried overnight at 100�C. Fresh 15-cc charges of Catalyst A were subjected to performance tests as described below. Performance Test 1 was conducted under conditions which might be used for a one- stage aromatization process with a mixed propane/butane feed. Performance Test 2 was conducted under conditions which might be used for the first stage of a two-stage aromatization process with a mixed propane/butane feed according to the present invention. Performance Test 3 was conducted under conditions which might be used for the second stage of a two- stage aromatization process according to the present invention .

For each of the three performance tests, a 15-cc charge of fresh (not previously tested) catalyst was loaded "as is," without crushing, into a Type 316H stainless steel tube (1.40 cm i.d.) and positioned in a four-zone furnace connected to a gas flow system. Prior to Performance Test 1, the fresh charge of Catalyst A was pretreated in situ at atmospheric pressure (ca.

0.1 MPa absolute) as follows: (a) calcination with air at approximately 60 liters per hour (L/hr) , during which the reactor wall temperature was raised from 25 to 510�C in 12 hrs, held at 510�C for 4-8 hrs, then further increased from 510�C to 630�C in 1 hr, then held at 630�C for 30 min; (b) nitrogen purge at approximately 60 L/hr, 630�C, for 20 min; (c) reduction with hydrogen at 60 L/hr, for 30 min, during which time the reactor wall temperature was raised from 630�C to 675�C. At the end of the above reduction step, the hydrogen flow was terminated, and the catalyst charge was exposed to a feed consisting of 50%wt ethane and 50%wt propane at atmospheric pressure (ca.

0.1 MPa absolute), 675�C reactor wall temperature, and a feed rate of 1000 GHSV (1000 cc feed per cc of catalyst per hr) . Three minutes after introduction of the feed, the total reactor outlet stream was sampled by an online gas chromatograph for analysis. Performance Test 2 was conducted in the same manner and under the same conditions as Performance Test 1 above, except that the final temperature reached during the air calcination pretreatment step was 600�C, the nitrogen purge and hydrogen reduction steps were conducted at 600�C, and the propane/n- butane feed was introduced at 600�C reactor wall temperature. This simulates the first stage of a two stage process. Performance Test 3 was conducted to simulate the second stage of a two stage process according to the present invention. For Performance Test 3, the fresh charge of Catalyst A was pretreated in situ at atmospheric pressure (ca.

0.1 MPa absolute) as follows: (a) calcination with air at approximately 60 liters per hour (L/hr) , during which the reactor wall temperature was raised from 25 to 510�C in 12 hrs, then held at 510�C for 4-8 hrs ; (b) nitrogen purge at approximately 60 L/hr, 510�C, for 30 min; (c) reduction with hydrogen at 60 L/hr, for 2 hrs. At the end of the above reduction step, the hydrogen flow was terminated, and the catalyst charge was exposed to a feed consisting of 100%wt ethane at atmospheric pressure (ca. 0.1 MPa absolute), 510�C reactor wall temperature, and a feed rate of 1000 GHSV (1000 cc feed per cc of catalyst per hr) . After 10 min at these conditions, the reactor wall temperature was raised to 621�C. At 25 min after introduction of the ethane feed, the total reactor outlet stream was sampled by an online gas chromatograph for analysis .

Table 1 lists the results of online gas chromatographic analyses of the total product streams from Performance Tests 1-3 described above.

Based on composition data obtained from the gas chromatographic analysis, initial ethane, propane, n- butane and total conversions were computed according to the formulas given below: Ethane conversion, % = 100 x (%wt ethane in feed - %wt ethane in outlet stream) /(%wt ethane in feed) Propane conversion, % = 100 x (%wt propane in feed - %wt propane in outlet stream) /(%wt propane in feed) n-Butane conversion, % = 100 x (%wt n-butane in feed - %wt n-butane in outlet stream) /(%wt n-butane in feed) Total ethane + propane + n-butane conversion = ((%wt ethane in feed x % ethane conversion) + (%wt propane in feed x % propane conversion) + (%wt n-butane in feed x % n-butane conversion) ) /100 TABLE 1 From Table 1, it can be seen that the one stage method produced 49.19%wt total aromatics from the given propane/n- butane feedstock, while the two stage method produced 57.28%wt total aromatics based on a 10

0%wt total feed to stage 1 followed by stage 2 which is fed with the ethane produced in stage 1.

In a true two stage operation, it is likely that the feed to stage 2 would include all non- aromatics from the outlet of stage 1 except the fuel gas (methane and hydrogen) . These non-aromatics would include not only unconverted ethane but also ethylene, propylene, propane, etc. which would likely increase the total aromatics yield to slightly more than 58%wt based on a 100%wt total feed to stage 1. Example 2 : Fig. 2 is a schematic flow diagram for producing aromatics (benzene and higher aromatics) from a feed containing 43.1 wt% propane and 56.9 wt% butane using a two stage reactor-regenerator system according to the present invention . 25 tonnes/hr (tph) of mixed feed (stream 1), which constitutes primarily 43.1 wt% propane and 56.9 wt% butane including minor amounts of methane, butane, etc. (stream 1) are fed to the stage 1 aromatization reactor 100 that uses "Catalyst A" described in example 1.

The first stage reactor 100 operates at about 1 atmosphere pressure and at a temperature of about 600�C while the stage 1 regenerator 200, which removes the coke formed in the reactor 100, operates at around 730�C. The heat required for the reaction step is provided by the hot catalyst solid mixture which is preheated during the regeneration step. The reactor 100 achieves almost complete conversion of butane and 98% conversion of propane. The reactor effluent stream 3a is then mixed with the reactor effluent from the second stage reactor 300 (stream 3b), described below. The combined effluent from both the reactor stages (stream 4) is then fed to a separation system where unconverted reactants and light hydrocarbons that consist primarily of ethane and some other hydrocarbons, which may include ethylene, propane, propylene, methane, butane and some hydrogen, are used as the feed (stream 2) for the stage-2 aromatization reactor 300 which uses "catalyst A" described above.

The second stage reactor 300 operates at about 1 atmosphere pressure and a temperature of about 620�C while the regenerator 400, which removes the coke formed in the reactor, operates at around 730�C. The heat required for the reaction step is provided by the hot catalyst solid mixture which is preheated during the regeneration step. The second stage reactor 300 converts almost half the ethane fed to it as was the case in performance test 3 in Table 1 above. The effluent from the second stage reactor 300 (stream 3b) is mixed with the effluent from the first stage reactor 100 as described above. Both stage-1 and stage-2 of the aromatization reactor system use a cyclic fixed bed design. The average single pass conversion for the mixed feed is obtained from the cumulative conversion of propane and butane (feeds) over both the stages and is calculated to be 99.95%. The liquid products are separated in a sequence of three consecutive columns to obtain the separated liquid products as shown in Figure 2. The process yields are summarized in Table 2 below.

This two-stage mode of operation produces about 8.1 tph of benzene (from column 600 through stream 10), 5.6 tph toluene (from column 700 through stream 11) and 1.2 tph xylenes (from column 800 through stream 12) resulting in an overall BTX yield of 59.7 wt% and an overall liquid yield of 71.1 wt% with respect to the mixed feed. The undesired fuel gas make (stream 8 from vapor-liquid separator 500) is about 7.1 tph which is about 28.6 wt % of the mixed feed. 2.3 Comparison of process configurations Table 2 below shows the comparison of the system performance for one stage and two stage processes. The processes are compared for conditions resulting in constant overall feed conversions. It is evident from Table 2 that the two-stage operation results in better product yields of benzene, toluene, mixed xylenes and C9+ liquids with lower undesired fuel gas make as compared to the one stage process.

Table 2 Note : • All yields are expressed as tonnes of the product per tonne of the mixed feed entering the overall process, expressed as percentage . • The average conversion per pass for a two-stage process is computed as: (Total propane conversion x mol fraction of propane in the mixed feed) + (Total butane conversion x mol fraction of butane in the mixed feed) Example 3 In this example the results of laboratory tests are used to represent a one-stage aromatization process vs. a two- stage process utilizing the same catalyst in each stage, with the temperature of the second stage being higher than the temperature of the first stage. To simulate a process in which unconverted byproduct ethane is recycled, the lower alkane feedstock of this example consists of 31.6%wt ethane, 29.5%wt propane, and 38.9%wt n-butane. Fresh 15-cc charges of Catalyst A (prepared as described in Example 1) were subjected to performance tests as described below. Performance Test 4 was conducted under conditions which might be used for a one-stage aromatization process with a mixed ethane/propane/butane feed.

Performance test 5 was conducted under conditions which might be used for the first stage of a two-stage aromatization process with a mixed ethane/propane/butane feed. Performance Test 3 (described in Example 1) was conducted under conditions which might be used for the second stage of a two-stage aromatization process according to the present invention. Performance Test 4 was conducted in the same manner and under the same conditions as those used for Performance Test 1 (described in Example 1), except that the feed for Performance Test 4 consisted of 31.6%wt ethane, 29.5%wt propane, and 38.9%wt n-butane. Performance Test 5 was conducted in the same manner and under the same conditions as those used for Performance Test 2 (described in Example 1), e except that the feed for Performance Test 5 consisted of 31.6%wt ethane, 29.5%wt propane, and 38.9%wt n-butane. Table 3 lists the results of online gas chromatographic analyses of the total product streams from Performance Tests 4, 5, and 3.

Based on the composition data obtained from the gas chromatographic analysis, initial ethane, propane, n- butane, and total conversions were computed according to the formulas given in Example 1 above. TABLE 3 The negative value recorded for % ethane conversion in Table 3 for Performance Test 5 indicates that the amount of ethane made as a byproduct of propane and/or butane conversion exceeded the amount of ethane converted in this test. Nevertheless, it can be seen from Table 3 that the one stage method produced 49.57%wt total aromatics from the given ethane/propane/n-butane feedstock, while the two stage method produced 53.20%wt total aromatics based on a 100%wt total feed to stage 1 followed by stage 2 which is fed with the ethane from stage 1. In a true two stage operation, it is likely that the feed to stage 2 would include all non- aromatics from the outlet of stage 1 except the fuel gas (methane and hydrogen) . These non-aromatics would include not only ethane but also ethylene, propylene, propane, etc.

which would likely increase the total aromatics yield to slightly more than 54%wt based on a 100%wt total feed to stage 1. Example 4 : What is a Cracker and Why Should I Care? | AFPM What is a Cracker and Why Should I Care? What is a Cracker and Why Should I Care? What is a Cracker and Why Should I Care? What are petrochemicals and how are they used? Ethylene is one of the most important chemicals in American manufacturing. Along with propylene, butenes, butadiene, benzene, toluene and xylenes, ethylene and other petrochemicals are used as building block materials that affect most manufacturing supply chains. Petrochemicals are unique substances that allow industrial scientists to create innovative products that are used every day throughout the world, from aspirin and medical equipment, to football helmets and bulletproof vests. Because ethylene is distinctive in its usefulness throughout chemistry, it is manufactured in greater amounts than any other chemical. The green double bond on the ethylene molecule gives it unique properties for chemistry. Graphic courtesy of Conrod Associates for AFPM What makes ethylene unique is a part of the molecule called a double bond.

That area is very reactive and particularly well-suited for many different chemical reactions, which makes ethylene one of the most important chemicals in all chemistry.The method for producing ethylene depends on high tech engineering and uses a tremendous amount of energy. The common term for this engineering feat is called cracking, because the energy is used to break apart (or crack) molecules and form new molecules, and the petrochemical plant is called a cracker. The most common feedstocks, or raw materials, for petrochemical manufacturing are naphtha and light gas oil, which are derived from the oil refining process, and individual gases such as ethane, propane and butane, which come from a complex mixture of hydrocarbons known as natural gas liquids, or NGLs. NGLs exist under the ground in a liquid state along with methane (natural gas), but several substances in the liquid hydrocarbon mixture are also gases above the ground at normal temperature and pressure. Each petrochemical facility is custom designed and engineered from the ground up. Photo courtesy of NOVA Chemicals The engineering design for the cracking process differs according to the type of feedstock used.

Because oil is a global commodity and is easy to ship long distances, many crackers around the world are configured to handle naphtha as a feedstock. Since ethane is more difficult – and expensive – to ship long distances, it can be considered more of a regional commodity. The regions that have an abundance of NGLs tend to also have the capacity to crack ethane. Those regions that do not have access to ethane usually do not have ethane crackers. Crackers in the US can often handle either naphtha or ethane. During the 1990s and early 2000s the instability and uncertainty over the price of oil and natural gas eventually led to technological advancements in domestic petrochemical processes. High tech American petrochemical manufacturers were able to achieve greater flexibility by reengineering their facilities to process a wider variety of feedstocks, whether derived from oil or NGLs. Feedstocks make up anywhere from 60 to 70 percent of the cost to manufacture petrochemicals; therefore, the feedstock flexibility of domestic petrochemical processes has enabled US producers to remain competitive.

As both oil and gas became more expensive in the US during the early 2000s, however, coupled with increased energy costs, the competitive advantage that came with feedstock flexibility all but disappeared. Petrochemical companies began to seek joint ventures in other parts of the world where energy and feedstock costs were cheaper. All that changed around 2008 when shale development led to a dramatic decrease in the cost of industrial energy and feedstocks here in the US. This modern gas well is directly connected to a gas processing plant, which is seen in the background. Shale development is providing manufacturers with an unprecedented opportunity in low cost energy; however, that is only part of the picture. Along with the natural gas and oil coming from shale plays like the Marcellus, Bakken, Utica and Eagle Ford, these areas contain an abundance of NGLs. Ethane is a major component of NGLs, especially in the Marcellus, Utica and Eagle Ford plays. The economic law of supply and demand states that an increase in supply, other things being equal, results in a decrease in price. This newfound bounty of NGLs has significantly reduced the price of ethane in the US.

The low cost of energy and ethane has prompted American petrochemical manufacturers to expand ethane cracking capacity. Over the past three years, petrochemical companies have announced plans to invest over $80 billion in new manufacturing infrastructure. How is ethylene made? The manufacturing supply chain begins with the extraction of natural resources. In the case of ethane, it begins with shale development, through a highly technical process that combines multi-dimensional seismic imaging, horizontal drilling and hydraulic fracturing. What comes out of the ground is a mixture of different liquid and gaseous hydrocarbons, so the next steps in the process are treating and processing the mixture to separate methane, which is also called natural gas or dry gas, from the liquids. Methane is used as fuel and as a feedstock for methanol and fertilizer production. The NGLs go to another type of separation facility called a fractionator, which separates the ethane, propane and butane. Once the ethane is separated it is shipped by pipeline to a cracker facility, which is a very sophisticated series of processes that convert the ethane to ethylene.

The first process is using steam to transport a mixture of ethane and a small amount of propane to a series of industrial furnaces and heating it to approximately 1500 degrees Fahrenheit, which requires a lot of energy. At that temperature single bond of the ethane molecule is loosened to the point that it loses two of the hydrogen atoms. The two hydrogen atoms combine and form a stable hydrogen molecule known as H2. In addition to ethylene, a number of other molecules are formed, but ethylene is in much greater abundance (about 80 percent) than the other substances. The next step is sending the mixture of very hot gases – liquids also become gases at that temperature – to a series of heat exchangers that use steam to cool the gaseous mixture. Once cooled, the mixture of steam and gases go to a tower where cold water is poured onto it from above to force all the different liquids to the bottom. These liquids are usually hydrocarbons with more than five carbon atoms. This process is also called quenching and the tower is referred to as a quenching tower. Two separate product streams come out of the quenching tower.

One product stream is water and a mixture of heavier hydrocarbons commonly referred to as pyrolysis gasoline. The water is cleaned and recycled back into the quench tower. The pyrolysis gasoline is sent to a separation unit that extracts the petrochemical aromatics (benzene, toluene and xylenes) for use in making plastics and other chemicals. The remaining liquid hydrocarbon mixture is used to blend in automotive fuels or sent to a refinery for further processing. The other product stream is a mixture of hydrogen (formed in the furnace when ethane is destroyed) and light hydrocarbons, including: Industrial distillation towers are giant high tech versions of the distillation columns found in chemistry labs. Methane Butenes Butadiene After leaving the quench tower, the gaseous mixture (including the hydrogen) goes to a compressor that squeezes the molecules together. From there the compressed mixture of gases goes to a condenser where it is further cooled, then to a high tech refrigeration unit called a cold box, which reduces the temperature to the point at which the mixture, other than methane and hydrogen, turns into a liquid.

Since ethane remains a liquid down to minus 128.2 degrees Fahrenheit (minus 89 C), the cold box has to be very, very cold. Once the gases are liquefied, the mixture goes through a series of tall towers called distillation units that are precisely controlled for temperature. Since liquefied gases boil (turn back into gases) at different temperatures, the distillation towers can control the isolation and removal of specific gases during this process. What happens to the ethylene? As stated earlier, ethylene is very reactive. It is also very flammable. For safety reasons, ethylene is usually transported by a special dedicated pipeline to other industrial chemistry facilities to make a variety of products called ethylene derivatives. One of the most common products made directly from ethylene is a plastic called polyethylene. The ethylene goes to a facility, usually in close proximity to the ethane cracker, and it gets converted through a chemistry process referred to as polymerization. The output of that facility takes the form of small plastic pellets called polyethylene resin. The polymer units are also custom-designed and engineered to control the specific physical properties of the resulting plastic resin.

That is why polyethylene is used in such diverse products ranging from sophisticated, high tech military helmets. Polyethylene resin takes the form of plastic pellets and can be colored prior to processing into a specific product. Ethylene is also used to make a variety of other chemicals. For example, if chlorine is added to the ethylene molecule it becomes vinyl chloride, which is the petrochemical derivative (building block) used to make polyvinylchloride or PVC. PVC is used as a corrosion-resistant material for modern plumbing, siding for houses, decking and many other applications in construction material supply chains. Flexible PVC is also used in medical tubing to replace glass and rubber because PVC is more resistant to other chemicals than rubber and, unlike glass, it does not break. Ethylene also reacts with other hydrocarbons in a chemical process called alkylation. If benzene (an aromatic petrochemical mentioned earlier) is mixed with ethylene, it reacts to form ethylbenzene. Ethylbenzene is a derivative petrochemical building block found in the manufacturing supply chains for Styrofoam and automobile tires. If oxygen is added to ethylene, it reacts to form the chemical ethylene oxide.

Ethylene oxide is used to make surfactants and detergents in the manufacturing supply chain for cleaning products. To take it even further, if water is added to ethylene oxide, it reacts in a process called hydrolysis and forms the product ethylene glycol. Ethylene glycol is used as an ingredient in antifreeze. It is also used to make a fiber called polyethylene terephthalate, otherwise known as polyester and can be found under the brand name Dacron®. Polyester resin is also used to make beverage bottles and a whole plethora of other useful products. The pervasiveness and importance of ethylene in manufacturing supply chains is undeniable. The significant increase expected in US ethylene production capacity will provide other manufactures with dependable raw materials at low cost all along the various supply chains. Manufacturers around the world are keeping a close eye on the petrochemical industry. Considering the low energy and raw material costs due to increased shale production, companies are beginning to realize that in the near future the United States may be the most competitive place in the world for the production of finished goods and consumer products.

How Natural Gas Liquids Go Their Separate Ways - Redorbit How Natural Gas Liquids Go Their Separate Ways by Sam Savage Separating natural gas liquids from natural gas is a natural part of the industry. It also is an area where ONEOK Partners is growing in a big way, with more than $1.1 billion in projects underway through the end of 2009. Natural gas liquids go into a variety of different products for consumers. Stripping those liquids out of the gas has to happen first, though. Natural gas liquids are ethane, propane, butane and natural gas. All of those are present in the natural gas -- methane -- that comes from completed wells. Terry Spencer, ONEOK Partners' executive vice president for natural gas liquids, said those liquids really aren't liquids at all, to start with. They come to natural gas processing plants as part of wells' vapor product. Natural gas processing plants, he said, start the process of recovering the natural gas liquids by cryogenically cooling the vapor. The dry gas that comes from that process -- the methane -- is natural gas used by homes, businesses, industries and some vehicles as fuel.

The gas is sent on to market, where it feeds a network of pipelines that distribute the gas across the country. What are left are natural gas liquids -- and they go by pipeline to another plant for additional processing. How separation occurs The ethane, propane, butane and natural gas are still are mixed together in a liquid form when they arrive at a natural gas liquids processing plant, known in the industry as a fractionator. ONEOK has three fractionators -- in Bushton, Kan., Conway, Kan., and in Medford. "That is where the magic happens," Spencer said. There, the liquid flows into a series of towers, each set to certain pressures and temperatures engineered to distill a particular product out of the liquid. First to be extracted is the ethane, using what Spencer describes as a mechanical process. The tower the liquid goes into is 125 feet tall, weighs three-quarters of a million pounds and has steel three inches thick. Heat is applied to the bottom of the tower to boil the liquid, sending the product being extracted to the tower's top as a semivapor. "All of these components each have different boiling points. So when you get the temperature right, you boil out certain products," Spencer said.

The ethane is drained into storage as it evaporates from the liquid. There, it cools. The remaining natural gas liquid, meanwhile, flows into the next fractionator tower. These subsequent towers extract the propane, butane and natural gas. Each of these is stored until they can be shipped down the pipeline to a customer, Spencer said. Who uses the liquids Spencer said the nation's petrochemical industry consumes more than 50 percent of natural gas liquids produced in the U.S., and much of that industry is on Texas' Gulf Coast at Mont Belvieu, near Houston. About 20 percent of the liquids also are used by refiners, and the remainder is used for commercial, industrial and residential needs. What has growth been? In 1995, ONEOK made $42.8 million in net income from its natural gas and natural gas liquids businesses. In 2007, the partnership made more than $304 million in net income from those businesses. The partnership acquired natural gas liquid assets from Koch Oil and Gas in 2005, giving it access to market hubs in Conway, Kan., and in Mont Belvieu.

It also is building a 760-mile natural gas liquids pipeline capable of carrying more than 100,000 barrels per day from Wyoming into Kansas, is building an extension onto that line into the Piceance Basin in Colorado, is expanding a fractionator in Bushton, Kan., is building a natural gas liquids pipeline to the Woodford Shale, and a pipeline from Oklahoma to Mont Belvieu. Ethane - Chemical Economics Handbook (CEH) | IHS Markit Chemical Economics Handbook Ethane Published May 2015 Ethane is a colorless and odorless gas at standard temperature and pressure. It is consumed as a feedstock in the production of ethylene (the largest end use, at 99%) or as an industrial fuel (a very small end use) and in other smaller uses (i.e., enhanced oil recovery operations). Nearly all ethane produced is consumed in the manufacture of ethylene and competes with other steam cracker feedstocks such as propane, butane, naphtha, and gas oil. Most ethane occurs with other natural gas liquids (propane and butanes) in associated or nonassociated natural gas reservoirs.

Smaller volumes of ethane are also recovered from refinery gases generated by catalytic cracking of petroleum fractions. In general, the supply and cost competitiveness of ethane are key drivers for feedstock selection for steam cracking. Although influenced heavily by unstable crude oil pricing, ethane and LPG feedstocks have gained an advantage in recent years with increases in natural gas and gas liquids production from improved oil and gas extraction techniques. Investments associated with transporting the highly volatile liquid to production centers are on the rise, while ethylene producers seek to improve operating margins for an expanding plastics industry. The following pie chart shows world consumption of ethane: North America and the Middle East are the largest consuming regions in the world because of abundant natural resources and considerable investment in gas processing and ethylene capacity. In the United States, the shale gas revolution, which led to increases in oil and gas production and improved cracking economics for lighter feedstocks (ethane, butane, and propane), has precipitated considerable downstream investment that is scheduled to come onstream during 2017–21. In the Middle East, ethane consumption will begin to slow as producers seek to increase by-product production through feedslate changes. Combined, these regions will remain the primary markets for ethane.

Central and Eastern Europe will experience the strongest regional growth as a result of environmental pressure. Mandates requiring a reduction in natural gas flaring will contribute to an increase in ethane production and associated cracker capacity. Strong growth will be seen in Africa, Mexico, and India but will largely come through individual capacity additions from a much smaller production base. Global ethane demand will rise approximately 6% through 2019 against the backdrop of slowing ethylene production (4% annual growth). The cost advantages gained through surplus ethane, even amid lower-cost crude oil, have resulted in an increase in ethane-based ethylene capacity. Naphtha will continue to be the dominant feedstock; however, the two will draw closer into balance by 2020. Development in China’s coal- and methanol-to-olefins technologies will experience the strongest gains, as new plants begin operation over the next several years. CEH: Ethane

Question: What comes next in this sequence: butane, propane, ethane, ... ?
Answer: Methane