Industrial Organic Chemicals (Wittcoff/Organic Chemicals) || Chemicals from Alkanes

CHAPTER 11

CHEMICALS FROM ALKANES

Alkanes occur as such in natural gas and petroleum and accordingly are the cheap-est raw materials for chemicals. They are the feedstocks for cracking (Sections 2.2.1,2.2.2) and catalytic reforming (Section 2.2.3). Methane is the main source for syn-thesis gas (Section 10.4) via steam reforming. The higher alkanes can be subjectedto the same process if desired, or the steam reforming process can be redirected togive methane. An important process is pyrolysis of hydrocarbons to carbon black,which is discussed at the end of this chapter.

Apart from pyrolysis, these reactions are endothermic. They are all unselectiveand take place at high temperatures. There are few examples of alkane functional-ization, that is, of the use of alkanes directly for downstream chemicals. The mostimportant are the conversion of n-butane to maleic anhydride (Section 5.4), the oxi-dation of n-butane or naphtha to acetic acid (Section 10.5.2.2), the oxidation ofisobutane to tert-butyl hydroperoxide (Section 4.11), the oxidation of ethylbenzeneto ethylbenzene hydroperoxide (Section 4.11) and the chlorination of methane(Section 10.2). Lesser volume uses involve ammoxidation of methane to hydro-cyanic acid (Section 10.1), conversion of methane to acetylene (Section 10.3), andnitration of propane. These have largely been discussed.

Any alkane may be nitrated. In practice, only propane is used as feed and from itsnitration result nitromethane, nitroethane, and 1- and 2-nitropropane. The nitrationtakes place at 420°C, and the products are separated by distillation. They are used asadditives for gasoline for racing cars, as solvents especially for polycyanoacrylates,

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Industrial Organic Chemicals, Second Edition, by Harold A. Wittcoff,Bryan G. Reuben, and Jeffrey S. PlotkinISBN 0-471-44385-9 Copyright © 2004 John Wiley & Sons, Inc.

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and as stabilizers of chlorinated solvents. Du Pont developed a process for the nitra-tion of cyclohexane to nitrocyclohexane as a step in a caprolactam synthesis (Section7.2.2), but it is not used today.

In the early 1990s a propylene shortage, primarily in Europe, motivated develop-ment of processes for the dehydrogenation of propane (Section 2.2.7). n-Butane alsomay be dehydrogenated to butadiene (Section 5) but it is more energy efficient to usen-butenes. The dehydrogenation of ethane to ethylene (Section 11.2.2) has not beencommercialized. Important in the 1990s was the dehydrogenation of isobutane toisobutene for methyl tert-butyl ether (MTBE, Section 5.2).

The functionalization of alkanes is a research goal not only because of the eco-nomic advantage of circumventing the cracking process, but also because reservesof methane—and to a lesser extent ethane, propane, and n-butane from natural orassociated gas—may last longer than those of petroleum. The current route to chem-icals from methane is via synthesis gas (Section 10.4) but the reaction is capital andenergy intensive. Hence, the aim is to functionalize methane by a direct process.

The strong and equivalent C�H bonds in methane make “bond activation” diffi-cult. Thus the functionalization of methane is a “holy grail” for the chemist. If it canbe successfully accomplished, the reward is great, because the chemical industrywill have the lowest cost raw material possible. Also, it will not be necessary in theshorter run to make the shift to coal with its inherent ecological problems.

11.1 FUNCTIONALIZATION OF METHANE

Early research on the functionalization of methane yielded only marginal results. Onthe basis of these efforts, it was easy to predict that chemistry would never be dis-covered to make methane the chemical industry’s basic building block. The 1980s,however, saw major advances in catalysis. Methane functionalization attracted in-tense research in the 1980s, which accelerated in the 1990s. In the 2000s, however,it became clear that the earlier pessimism was not unfounded and that, despite theprogress that had been made, methane functionalization was an elusive goal anddepended on catalyst development that could not easily be foreseen.

Three reactions provide the goals. These are the direct oxidation of methane tomethanol and/or formaldehyde; the dimerization of methane to ethane, ethylene, orhigher hydrocarbons; and the aromatization of methane.

11.1.1 Methane to Methanol and Formaldehyde

The oxidation of methane to methanol and formaldehyde is burdened by the fact thatformaldehyde is 21 times more susceptible to oxidation than methane at 670°C.Methanol is even more sensitive to oxidation. Of the scores of patents issued, the oneto Hüls is typical. Methane and oxygen are mixed at 300–600°C at a pressure of400 bar. Residence time is a critical 10�3 seconds. Conversions per pass, however,are no greater than 3%. The process is not currently economical because of the highcapital investment, which the short residence time and the low-conversion ratesnecessitate. These negative factors provide the incentives for further research.

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Nitrous oxide appears to be a particularly good oxidant for methane and twoJapanese patents (see notes at the end of this chapter) claim its use with catalystssuch as Mo3 /SiO2 and V2O5 at 450–550°C. A 93% selectivity to formaldehyde wasobtained but at a conversion of only 0.5%. At 11% conversion, a 98% selectivity wasobtained to a mixture of methanol and formaldehyde. At this latter conversion, theprocess shows some promise, but its practicality is questionable because the molarratio of nitrous oxide to methane must be 2:1. Nitrous oxide has historically been anexpensive oxidant because it could not be made directly from nitrogen and oxygenand required a roundabout route via ammonium nitrate. Oxygen atoms do not inter-act with nitrogen because the process, written in spectroscopists’ notation:

is spin forbidden. What that means is that the nitrogen molecule has no unpairedelectrons, and oxygen atoms have two, hence the total electron spin of the productsshould be two, not zero as in nitrous oxide. The reaction to give two molecules ofNO, each of which has one unpaired electron, is far more likely.

In the mid-1990s Mitsui Toatsu developed a route to nitrous oxide via catalyticreaction of oxygen and ammonia. The Mitsui Toatsu catalyst is a copper–manganeseoxide (CuO�MnO2).

Solutia, who is pioneering the reaction of benzene with N2O to yield phenol (Section7.1), has tried to lower the costs of this route even further by replacing the oxygenwith air. Ammonia is still more expensive than nitrogen but not nearly as expensiveas ammonium nitrate. Industrial oxidations of alkanes or aromatics with nitrousoxide may become practical in the future.

Typical of more recent work is a Catalytica process in which methane reacts withsulfuric acid to yield methyl hydrogen sulfate CH3OSO3H, which can be easilyhydrolyzed to methanol and recoverable sulfuric acid. The original catalyst was mer-cury based, which would cause environmental concerns if used in a large scaleprocess. Catalytica was able to replace this with a platinum complex. At 180°C,selectivity to methanol was 86%. This approach has the potential to lower the costof methanol production by obviating the need to reform methane to syngas. Beforeit can be commercialized, however, both reaction rate and yield must be improved.

11.1.2 Dimerization of Methane

The dimerization of methane to ethane and ethylene has been extensively studied. Inthe Benson process, methane is burned in chlorine in a highly exothermic reaction atan adiabatic flame temperature of 700–1700°C. As might be expected, huge amountsof hydrogen chloride are obtained, which must be reconverted to chlorine or used insome other way. This seriously inhibits commercialization of the process.

Catalytic oxidative coupling of methane has also been explored. Thus it has beenshown that lithium-doped magnesium oxide in the presence of oxygen will extracthydrogen from methane to form methyl radicals, which in turn combine to produce

2NH3 + 2O2 N2O + 3H2O

N2(1Σg+) + O(3P) N2O(1Σg

+)

FUNCTIONALIZATION OF METHANE 389

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ethane and ethylene at 720°C. Conversion is about 38% with a selectivity of about50%. ARCO has been able to obtain conversions up to 15% with selectivities of 78%to C2–C7 compounds, mostly ethane and ethylene. One catalyst described is man-ganese acetate with sodium promoters. In other work nitrous oxide was used.

In 1993, the University of Minnesota suggested the feasibility of oxidative cou-pling of methane to give ethylene at 830°C in the presence of oxygen and samariumoxide Sm2O3. Yields of 60% were claimed as opposed to previously achieved valuesof 25%. The key appears to be the shifting of equilibrium by the rapid removal ofoxygen, methane, and ethylene. More recent work from Amoco (now part of BP)improves the oxidative coupling process by integrating the exothermic methane coupling reaction with an endothermic cracking of saturated hydrocarbons in a dual-flow reactor. The heat produced in the methane coupling reactor is transferredthrough the walls of the reactor tubes to the second cracking zone.

The direct conversion of methane to acetic acid with oxygen, rhodium chloride,and water at 100°C has been accomplished at Pennsylvania State University, althoughreaction rates are very low.

11.1.3 Aromatization of Methane

The conversion of methane to aromatics has been studied by BP. The aromatizationis accomplished in the presence of an oxidant, nitrous oxide, with an acid catalyst,a gallium-doped H-form zeolite. Methane conversion of 39% per pass has beenreported with selectivities to aromatics of 19%. Although such results are promising,the economics are doubtful because 1 mol of nitrous oxide is consumed for every twoC�H bonds that are broken. Also, additional oxidant is consumed in the undesirableformation of carbon oxides. Either one needs a way of using the oxidant catalyticallyrather than stoichiometrically, or a cheaper oxidant should be found, or a less expen-sive method for producing nitrous oxide should be developed (Section 11.1.1).

As mentioned above, methane can be halogenated under mild conditions. In aproposed process for converting methane to gasoline, chloromethane is dehydro-halogenated under conditions such that coupling takes place simultaneously to giveC2–C5 olefins which, under the conditions of the reaction, recombine to providegasoline-range paraffins and aromatics. Some olefins are also produced. In the process,hydrogen chloride is evolved and is reused for oxychlorination of the methane:

A report from the University of Minnesota indicates that platinum or rhodium cata-lysts effect the conversion of methane to synthesis gas (Section 10.4) at ambient tem-peratures. Selectivity and conversions are reported to be high.

CH3Cl HCl + C2–C5 olefins

AlkanesAromaticsCycloalkanesC4

+ olefinsCoke

Methylchloride

CH4+O2

Oxychlorination


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11.2 FUNCTIONALIZATION OF C2–C4 ALKANES

The commercialized reactions in which alkanes have been oxidized were listed at thebeginning of this chapter. Several interesting processes, not yet commercialized,have been described in the literature.

11.2.1 Oxidation of C2–C4 Alkanes

The oxychlorination of ethane to vinyl chloride may be carried out with a metallicsilver–manganese catalyst in combination with other compounds such as lanthanumsalts, either in the particulate form or impregnated on a zeolite, to provide vinyl chlo-ride at 400°C and atmospheric pressure.

Contact time is 1–2 seconds. Complete conversions can be obtained with selectivityto vinyl chloride as high as 50%. This process, patented by ICI, showed promise and commercialization is predicted by about 2005. An earlier process devised byLummus using conventional oxychlorination catalysts yielded selectivities of 37% at28% conversion.

Monsanto studied the oxychlorination of ethane to vinyl chloride in a vapor-phasefluidized bed reactor with a catalyst comprising alumina-supported copper halideand potassium phosphate at 550°C. Ethyl chloride is a byproduct, which can subse-quently be oxidatively dehydrogenated to vinyl chloride. Ethylene dichloride by-product can be cracked by conventional means to vinyl chloride. Conversions of theorder of 85–90% based on hydrogen chloride can be achieved with selectivities ashigh as 87% based on ethylene.

More recent work by European Vinyls Corporation (EVC) has led to promisingresults. In the EVC process, ethane is catalytically oxychlorinated to vinyl chloride inan integrated multistep process. Because a significant amount of chlorinated hydro-carbons, both saturated and unsaturated, are formed in the primary oxychlorinationstage, it is critical to the economics of the process to recycle the byproducts to reducewasted feedstock. The unsaturated chlorinated byproducts are converted to saturatedproducts by a separate hydrogenation stage and then dehydrochlorinated to vinylchloride. By recycling the byproducts, a very high overall vinyl chloride yield isachieved. The EVC process operates at low-temperatures relative to earlier attemptsat ethane oxychlorination. This is crucial, as high temperatures and a chlorine-containing environment are extremely corrosive, and the metallurgy required to con-tain such a system is exotic and expensive.

In the mid-1980s, Union Carbide developed the Ethoxene (Section11.2.2) processto produce acetic acid via the catalytic gas-phase oxidation of ethane. The problemwas the simultaneous production of substantial quantities of ethylene as well asacetic acid, and development of it seems to have been abandoned. In 2000, SABIC

CH3CH3 + 0.5O2 + Cl2 CH2 CHCl + H2O + HCl

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announced its intention to build a pilot plant based on catalytic ethane oxidationusing its own proprietary Sabox process, which makes acetic acid in selectivities ofup to 60% with little or no ethylene coproduct. This might be an economic source ofacetic acid, given the low cost ethane available to SABIC.

The ammoxidation of propane to acrylonitrile has been studied for many years byBP and was targeted for commercialization in the late 1990s. By 2004, plans had stillnot reached fruition. The reaction is postulated to proceed by way of a propyleneintermediate. One proposed catalyst, in an early patent issued to another developer,Monsanto, comprises a mixture of antimony and uranium oxides with a halogen pro-moter such as methyl bromide. Antimony was a first generation and uranium a sec-ond generation catalyst for the ammoxidation of propylene (Section 4.8). Reactiontakes place at 500°C to give 71% selectivity at 85% conversion for a yield per passof 60%. Raw material savings are somewhat eroded by the higher capital costs of the process. Newer patents describe catalysts comprising a mixture of vanadium,antimony, phosphorus, and cobalt as well as bismuth, vanadium, molybdenum,chromium, and zinc. These provide lower yields per pass but may have other advan-tages. In addition to BP, two Japanese companies, Asahi Chemical and MitsubishiChemical, have been active in developing propane ammoxidation processes that canbe run in two modes. One mode requires operation at modest per pass propane con-versions to maintain high selectivities to acrylonitrile. This requires unreactedpropane to be recycled and necessitates the use of oxygen instead of air, because thenitrogen in the air builds up in the recycle loop. The alternative mode is to run at highconversions per pass without recycling the unreacted propane. This route has higherpropane consumption but permits the use of air as the oxidant. It remains to be seenwhich approach, if either, will eventually be commercialized. Catalytic oxidation ofpropane to acrylic acid is also under development. Promising patents have beenawarded to Mitsubishi Chemical, Toagosei, BASF, and Sunoco. No commercializa-tion plans have been announced thus far.

Catalytic oxidation of n-butane to maleic anhydride was discussed in Section 5.4.This process, commercialized more than 30 years ago, is still the only transitionmetal catalyzed alkane activation process to achieve widespread use. A spin-off ofthis technology are processes to convert n-butane to 1,4-butanediol and tetrahydro-furan (Section 5.4). These processes, all proceed via hydrogenolysis of maleic anhy-dride or maleic acid. As far as the alkane activation component of the process isconcerned, they are simply variations on the maleic anhydride technology.

In a reaction analogous to the oxidation of butane to acetic acid, propane or a propane–butane mixture can be oxidized at about 450°C and 20 bar to acetalde-hyde and a large number of other oxygenated compounds. The reaction can be con-ducted either in the liquid or gaseous phase and has been used commercially in theUnited States. In a related development ICI has oxidized ethane in the presence ofhydrogen chloride to acetaldehyde. A silver manganate catalyst, AgMnO4, is used at360°C. Conversion is 14% and selectivity to acetaldehyde is 71%. Chlorinatedbyproducts such as methyl and ethyl chloride can be recycled to inhibit theiradditional production.

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11.2.2 Dehydrogenation of C2–C4 Alkanes

Dehydrogenation of ethane, propane, or butane to the corresponding olefins is analternative to steam cracking that requires higher temperatures and greater capitalinvestment. Nonetheless, as the worldwide demand for polypropylene continues togrow, there is concern that conventional sources of propylene will be inadequate.Propane dehydrogenation has been commercialized and is discussed in detail inSection 4.1.

n-Butane is seldom if ever dehydrogenated because of the large energy input re-quired. The dehydrogenation of butenes to butadiene is carried out commercially inthe United States (Section 5). A further C4 dehydrogenation reaction currently in useinvolves conversion of isobutane to isobutene, the latter being required for MTBEproduction (Section 5.2.1). The reaction takes place readily, unlike most dehydro-genations, because the tertiary hydrogen is an excellent leaving group. Isobutane isalso used as feedstock for propylene oxide (Section 4.11). The isobutane is oxidizedwith air to tert-butyl hydroperoxide, which is used as the source of oxygen in the cat-alytic epoxidation of propylene to propylene oxide. tert-Butanol is a byproduct ofthis reaction. It can be dehydrated to isobutene for reaction with methanol overacidic ion exchange resins to yield MTBE. Alternatively, the tert-butanol can bedirectly converted to MTBE. This approach to propylene oxide production is notexpected to grow, as the future of MTBE is in doubt. Dehydrogenation of isopentanehas been used to make isoprene.

Petroleum wax fractions from lubricating oil dewaxing can be dehydrogenatedto α-olefins. Hydroformylation (Section 4.12) then gives detergent range alco-hols. For example, Sasol in Augusta uses UOPs Pacol process to dehydrogenateparaffins and separates the product olefins from the starting paraffins by UOPsOlex process. These processes could possibly be improved if oxidative dehydro-genation were possible. Thus far, successful processes have not evolved, becausethe products oxidize more readily than the starting material. Meanwhile, waxcracking has been used in the past in Italy and by Chevron to obtain an n-alkane–olefin (not necessarily alpha) mixture used to alkylate benzene to givealkylbenzenes for detergent use. The dehydrogenation of ethane to ethylene ismore difficult than that of the higher hydrocarbons. Many companies haveworked in this field. Union Carbide, as indicated earlier (Section 11.2) hasdevised an oxidative dehydrogenation in the vapor phase to produce a mixture ofethylene and acetic acid. The ratio of the two products can be varied from 1:1 to5:1. The catalyst comprises molybdenum and vanadium doped with niobium,antimony, and one other metal, which can be calcium, magnesium, or bismuth.The reaction takes place at 330 –435°C with conversions of about 30% and selec-tivities as high as 90%. Although this might provide a convenient route to aceticacid without requiring the investment for dedicated plants, the imbalance betweenethylene and acetic acid demand (55 vs. 4.5 billion lb, in 2002) means that itcould never be the sole source of ethylene. If it were, a large surplus of acetic acidwould be produced.

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11.2.3 Aromatization of C2–C4 Alkanes

Since ease of aromatization increases with molecular weight, ethane aromatizesmore readily than methane, and propane and butane aromatize more readily thanethane. The dehydrocyclization of alkanes, primarily propane and butane or lique-fied petroleum gas (LPG) to aromatics, provides the basis for BPs and UOPs Cyclarprocess for which a demonstration plant was operated in the early 1990s. In the late1990s, a plant was built and is operating in Saudi Arabia.

The Cyclar process uses a propane–butane (LPG, Section 2.1) mixture in areaction maintained at 535°C and 6 bar with a contact time of 14 seconds. Twenty-nine percent conversion with 95% selectivity to aromatics results. The processcould be useful as a source of benzene in areas like Saudi Arabia where pyrolysisgasoline (Section 2.2.1) is not available and where very little catalytic reforming(Section 2.2.3) is done. The BTX distribution with propane and butane as feeds isshown in Table 11.1.

The aromatization of ethane takes place with a gallium- or platinum-doped ZSM-5 zeolite catalyst. The shape selective property of the catalyst (cf. Section 8.1,toluene disproportionation) promotes the selective formation of cyclohexane andmethylcyclohexane. Dehydrogenation provides benzene and toluene. The inlet tem-perature is about 700°C. Because the reaction is endothermic, a high input of heatper pound of ethane converted is required. The reaction is carried out at 2 bar andthe ethane conversion per pass is about 33%. Of this, 30 mol% is methane and 60%is benzene and toluene. Less than 2% is higher hydrocarbons.

11.3 CARBON BLACK

Many petrochemical processes are seriously hindered by the formation of carbon,which poisons catalysts and blocks furnace tubes. Thermodynamically, alkanesincline toward carbon and hydrogen as the most stable products. The production ofcarbon from alkanes, including methane, is thus relatively easy.

Carbon black is an amorphous graphite or soot consisting of highly aromatic car-bon structures of colloidal size. It is made by partial combustion or combustion plusthermal cracking of hydrocarbons at 1300–1400°C. The feedstock may be an alkane


TABLE 11.1 Aromatics Yield from Aromatization ofPropane and Butane (%)

Propane Butane

Benzene 32.0 27.9Toluene 41.1 42.9Xylenes 18.9 21.8C9 and C10 Aromatics 8.1 7.4

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NOTES AND REFERENCES 395

or olefin or almost any hydrocarbon. Methane was once used widely but is no longereconomic. Gas oil and residual oils are now popular especially from sources high inaromatics.

Many grades of carbon black are produced, varying primarily in particle size(between 10 and 500 nm) and surface area but also in other properties important inrubber compounding. About 60% is used in tires to provide abrasion resistance andmechanical strength to the rubber. The remaining 40% goes into other elastomers,printing inks, paints, and plastics.

This mature carbon-black technology has been slightly perturbed by the appear-ance of nanoparticles, a term generally used to indicate particles with dimensionsless than 100 nm, so that traditional carbon blacks overlap with the nanoparticleregion. The smallest nanoparticles, only a few nanometers in diameter, contain onlya few thousand atoms. These particles are called quantum dots and can possess prop-erties that are entirely different from the bulk materials.

Nanostructured silica–carbon powders of the kind that could be used in tires aremade in a so-called turbulent diffusion flame reactor based on a conventionalhydrogen–air burner. Hexamethyldisiloxane is fed into the flame and the productscollected. Pure silica and composite silica–carbon nanoparticles result from oxida-tion of hexamethyldisiloxane, (CH3)3Si�O�Si(CH3)3.

The combination of carbon black and silica is more effective in reinforcing rub-ber than carbon black alone, providing the capability for manufacture of so-called“green tires.” As the silica surface is covered with silanol groups, adding anorganosilane coupling agent forms a silica network in the rubber. This filler-to-fillernetwork enhances the tire reinforcement and decreases the rolling resistance by upto 24%, while wet traction and tread wear are similar to conventional tires. Fuel con-sumption is significantly decreased and air and environmental pollution reduced.The problem, of course, is the price. The siloxane starting materials are not cheapand the products market at $2.5–5/lb, compared with typical carbon black prices of$0.40/lb.

Automobile tires now last longer and more automobiles are imported into theUnited States. Hence, the United States carbon black market has declined fromabout 3.5 billion lb/year in the early 1970s to about 2.5 billion lb/year in the early2000s. It nonetheless remains an important chemical and the global market is 12 bil-lion lb/year.

NOTES AND REFERENCES

Nomenclature again: The term alkane is generally preferred to paraffin in the indus-trial chemical literature. The unsaturated counterpart of an alkane is an alkene, andto be consistent this term should be used. However, the industry overwhelminglyprefers olefin, which, from the point of view of nomenclature, is the unsaturatedcounterpart of a paraffin. We had little choice in this chapter but to follow the indus-try practice of using the word olefin but only occasionally the corresponding wordparaffin, which is virtually unknown outside textbooks.

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A good overview of commercially promising alkane activation technologies isNexant Chemsystems’ multiclient report, Alkane Activation: Petrochemical Feed-stocks of the Future (June, 1999).

Section 11.1 In addition to the references on methane conversion either tomethanol or ethylene, the following, which are but a small sample of the literature avail-able, provide examples of the interest the chemical trade press has taken in this topic.Chem. Eng. News, April 10 (1989) p. 5; ibid., July 4 (1988) p. 22; ibid., January 18(1988) p. 27; ibid., May 9 (1988) p. 45; ibid., September 28 (1987) p. 23; ibid.,September 14 (1987) p. 19; ibid., June 1 (1987) p. 22; Chem. Week, October 21 (1987)p. 49, CHEMTECH, August (1987) p. 501; N. D. Parkyns, Chem. Brit. 26, 841 (1990).

Section 11.1.1 The Catalytica and University of Minnesota work have beenreported in Chem. Eng. News, January 18 1993, p. 6, ibid. October 11 1993, p. 4, andScience 262, 221 (1993). Catalytica’s mercury-based catalyst is described in US Patent5,305,855 (April 26, 1994) and the platinum-based catalyst is described in WorldPatent 98/50,333 (November 12, 1998).

The Hüls oxidation of methane to methanol is described in German Patent2,743,113 (1979).

Japanese Patents 189,249-250 (November 27, 1981) to I. Masakazu describe theoxidation of methane with nitrous oxide to methanol and formaldehyde. MitsuiChemical’s catalytic oxidation of ammonia to nitrous oxide is described in US Patent5,849,257 (December 15, 1998).

Section 11.1.2 For the University of Minnesota work, see reference in Section11.1.1. The conversion of methane to acetic acid is described in Chem. Week, April20, 1994, p. 8.

The process in which methane is burned in chlorine is described in US Patent4,199,533 (April 22, 1980) to the University of Southern California.

The lithium-doped magnesium oxide catalyst for methane coupling has beenexplored by T. Ito and J. Lunsford, Nature (London) 314, 25 (1985).

The conversion of methane to gasoline, described in a patent to Atlantic Richfield(US Patent 4,849,751, July 18, 1989), is accomplished by oxidatively couplingmethane to convert it to a mixture of ethylene, carbon monoxide, and hydrogen. Themixture is then treated with a dual function catalyst comprising ZSM-5 and an oxideof cobalt, rutheniun, copper, zinc, chromium, or aluminum. The zeolite oligomerizesthe ethylene to gasoline-sized molecules whereas the oxide, as in the Fischer–Tropsch reaction (Section 12.2), converts CO and H22 to gasoline-range molecules.This is a clever approach, typical of what will be needed if methane functionaliza-tion is to become practical.

Typical of the ARCO patents that claim methane conversion to higher hydrocar-bons, are US Patents 4,443,644-649 (April 17, 1984); US Patents 4,544,784-787(October 1, 1985); US Patents 4,547,607-64 (October 15, 1985); US Patent 4,499,322(February 12, 1985); US Patent 4,517,398 (May 14, 1984); US Patent 4,523,049 (June11, 1985); US Patent 4,523,050 (June 11, 1985); US Patent 4,556,749 (December 3,1985); US Patent 4,560,821 (December 24, 1985); US Patent 4,568,785 (February 4,1986); and US Patent 4,554,395 (November 19, 1985).

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Section 11.1.3 The conversion of methane to aromatics is described inEuropean Patent Appl. 0,093,543 (November 9, 1983).

The catalyst for the conversion of chloromethane to gasoline-range hydrocarbonscomprises zeolites doped with cations such as zinc, gallium, or silver. Reaction takesplace at ∼325°C and 3 bar.The conversion is described in two International PatentAppl. WO85/02608 (June 20, 1985) and WO85/04863 (November 7, 1985) to BritishPetroleum.

Section 11.2.1 The ICI process for oxychlorination of ethane is described intwo British Patent Appl. (2,095,242A and 2,095,245A) (September 29, 1982). Theolder Transcat process is claimed in US Patent 3,775,229 (January 19, 1971) toLummus.

The Monsanto process for vinyl chloride is claimed in US Patent 4,300,005(November 11, 1981).

The Europeans Vinyls Corporation’s ethane to VCM process is described in a seriesof patents: EP 0 667 844B1 (February 4, 1998), WO 95/07252 (March 16, 1995), WO95/07251 (March 16, 1995), WO 95/07250 (March 16, 1995), WO 95/07249 (March16, 1995).

The ICI process for acetaldehyde formation with a silver catalyst is claimed in USPatent 4,415,757 (November 15, 1983).

Standard Oil of Ohio’s (BP America) patents describing propane ammoxidationinclude US Patent 4,873,215 (October 10, 1959) and European Patent Application0,282,314 (March 10, 1988). An early Monsanto patent is West Germany Patent2,056,326. Mitsubishi Chemical patents on propane ammoxidation include US Patent5,750,760 (May 12, 1998) and WO 98/22421 (May 28, 1998). Asahi Kasei patents onthis subject include US Patent 5,780,664 (July 14, 1998) and US Patent 5,663,113(September 2, 1997).

A particulary interesting patent describing propane to acrylic acid technology isBASF’s US Patent 6,541,664 (April 1, 2003). The yield to acrolein and acrylic acidcombined is 85%.

Section 11.2.2 Carbide’s ethane dehydrogenation process is the basis for USPatent 4,524,236 (June 18, 1985) to Union Carbide.

The Cyclar process is described in a number of patents including UK Patent Appl.GB2,082,157A (March 3, 1982); European Patent Appl. 0,202,000 A1 (November20, 1986); US Patent 4,613,716 (September 23, 1986), and US Patent 4,642,402(February 10, 1987). All of these patents are held by BP except the last one, issuedto UOP, which cooperated with BP on the development.

Wax cracking is described by Weissermehl and Arpe in their definitive text onindustrial organic chemistry, cited in Section 0.4.2.

Section 11.2.3 The conversion of ethane to aromatics is described in a Mobilpatent (US Patent 4,350,835, September 21, 1982).

Section 11.3 The web provides numerous sources. Political implications are atwww.volpe.gov.infosrc. Apart from these, we have drawn on A. M. Thayer, SpecialReport: Nanotechnology, Chem. Eng. News, October 16, 2000; S. E. Pratsinis, Flameaerosol synthesis of ceramic powders, Prog. Energy Combust. Sci. 24, 197 (1998);

NOTES AND REFERENCES 397

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T. J. Byers and A. A. McNeish, Current advances in tire compounding technologyfor rolling resistance, paper presented at the Carbon Black World 1997 Conference,San Antonio, TX; and H. K. Kammler and S. E. Pratsinis, Scaling up the productionof nanosized SiO2 particles in a double diffusion flame reactor, J. Nanoparticle Res.1, 467(1999).


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Industrial Organic Chemicals (Wittcoff/Organic Chemicals) || Chemicals from Alkanes