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Reactions of Synthesis Gas | Gasification | Methanol

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Fuel Processing Technology 48 (I 996) 189-297 Reactions of synthesis Irving Wender Chemicd und Prtrolrum Engineering Depurtment, University gas Pittsburgh, PA 15261. USA oj’ Pitt.shurgh. Abstract The use of synthesis gas (syngas) offers the opportunity to furnish a broad range of environmentally clean fuels and chemicals. There has been steady growth in the traditional uses of syngas. Almost all hydrogen gas is manufactured from syngas and there has been a tremendous spurt in the demand for
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  Fuel Processing Technology 48 (I 996) 189-297 Reactions of synthesis Irving Wender gas Chemicd und Prtrolrum Engineering Depurtment, University oj’Pitt.shurgh. Pittsburgh, PA 15261. USA AbstractThe use of synthesis gas (syngas) offers the opportunity to furnish a broad range ofenvironmentally clean fuels and chemicals. There has been steady growth in the traditional uses ofsyngas. Almost all hydrogen gas is manufactured from syngas and there has been a tremendousspurt in the demand for this basic chemical; indeed, the chief use of syngas is in the manufactureof hydrogen for a growing number of purposes. Methanol not only remains the second largestconsumer of syngas but has shown remarkable growth as part of the methyl ethers used as octaneenhancers in automotive fuels. The Fischer-Tropsch synthesis remains the third largest consumerof syngas, mostly for transportation fuels but also as a growing feedstock source for themanufacture of chemicals, including polymers. Future growth in Fischer-Tropsch synthesis maytake place outside the continental United States. The hydroformylation of olefins (the 0x0reaction), a completely chemical use of syngas, is the fourth largest use of carbon monoxide andhydrogen mixtures; research and industrial application in this field continue to grow steadily. Adirect application of syngas as fuel (and eventually also for chemicals) that promises to increase isits use for Integrated Gasification Combined Cycle (IGCC) units for the generation of electricity(and also chemicals) from coal, petroleum coke or heavy residuals. In the period 2005-2015, theamount of syngas employed in this manner may approach that used for all other specific purposes.Syngas is the principal source of carbon monoxide, which is used in an expanding list of so-calledcarbonylation reactions. 0. Overview Synthesis gas (syngas), a mixture of hydrogen and carbon monoxide, can bemanufactured from natural gas, coal, petroleum, biomass and even from organic wastes,so that sources of syngas are ubiquitous in nature. The availability and flexibility of theresource base are keys to the present and future uses of syngas and of its separatecomponents, hydrogen and carbon monoxide. Syngas is a present and increasing sourceof environmentally clean fuels and chemicals and is also a potentially major fuel for the 037%3820/96/$15.00 Copyright 0 1996 Elsevier Science B.V. All rights reserved. PII SO378-3820(96)01048-X  190 1. Wetuler/Fuel Processing Technology 48 (1996) 189-297 production of essentially pollution-free electricity, as sulfur and nitrogen in parts permillion can be removed from syngas relatively easily.This report will list the commercial uses of syngas in the order of their importance,compare them with uses of a decade ago and outline what promises to be a bright futurefor this mixture of gases.There are literally thousands of published papers and proceedings of various confer-ences that deal with syngas reactions. A very large number of these publications dealswith catalytic reactions of syngas in an exploratory way aimed often at the elucidation ofmechanistic pathways. These researches provide an understanding of various aspects ofsyngas reactions and point the way to possible future commercial applications and tonew uses of syngas; they will be referred to when they are of particular pertinence.References to some of the large number of patents that deal with the chemistry and usesof syngas will be referred to occasionally but are not a major source of material for thisreview.The birth of syngas chemistry occurred in the early part of the 20th century. Methanewas produced by the hydrogenation of carbon monoxide in 1902, followed by thediscovery of the synthesis of ammonia (NH,) in 1910. The Fischer-Tropsch synthesiswas developed in the following decade and then came the manufacture of methanol andhigher alcohols, Syngas is now used in a host of different ways.The uses and reactions of syngas in the light of changes that have taken place from1984 to 1994, with an update, constitute the body of this report. The chemistry of theseparate components of syngas, H, and CO, will be discussed in some detail. It isremarkable that, although these are apparently simple diatomic molecules, they arereadily adsorbed in diverse ways on the surface of catalysts. Together with carbondioxide, CO,, they form an unexpectedly large number of complex species with bothheterogeneous and homogeneous catalysts.The principal fuel uses of syngas in 1994 are given in Fig. 1. The major commercial,near commercial and potentially commercial chemical uses of syngas in 1994 areoutlined in Fig. 2. Wender and Seshadri (1984) summarized the fuel and chemical usesof syngas in 1984 (Figs. 3 and 4). Although it appears from a comparison of the FISCHER-TROPSCH Gasoline - DieselChemicalsMETHANOL isobulylene@ME)- MTBE Medium BTU GAS(Turbine fuel. ICCC) GasolineFig. 1. Principal commercial fuel uses of synthesis gas (1994).  I. Wen&r/Fuel Processing Technology 48 (1996) 189-297191 DIMETHYLACETICFORMIC ACIDCARBONATEANHYDRIDE\ETHYLENE\ CHEMICALS WAXESMETHYL ACETATE\ T HjOllFC FORMALDEHYDEAMMONIAC+ ACETIC ACID co .I’ ,’ Rh ,.’ CHLORCO I METHANE5METHYLiIAMINES 02 b’ ” Acelaldeh deEthsno r (hydroformylation) I h Co I ZSM-5 (Zeolites) IEthyleneI i ALDEHYDES J OldillS ALCOHOLS (Z-ethylhexanol)Aromatics 4 VINYL ACETATE ___ Commercial. -. Near commercial, perhaps availnble for license . . . . . . . Polenlial (next decade)- Fig. 2. Commercial, near commercial and potential chemicals from synthesis gas (I 994). corresponding figures that there have been no significant new uses of syngas in the pastdecade, there have been great increases in the“traditional” uses of syngas as newoutlets have appeared. GASOLINEDIESEL OIL~_ZBO!l!?r.F,SCHER_TROPSCH~ GASOLINE1/ DIESEL OIL,*’OTHER PRODUCTSFUELC,-C6 ALCOHOLS MTEIECELLSMETHANEFUELH:,ISOSYNTHESIS GASOLINE (neat)DIESEL OILAROMATICS (BTX) ____ commercial processes-.-.-.- processes commercial III 1984-85-~~-~~~~~~-~-~~ processes possibly for llle nsxl decade Fig. 3. Commercial or near commercial processes for the production of liquid fuels from synthesis gas(Wender and Seshadri, 1984).  192I. Weruler/ Fuel Processing Technology 48 (1996) 189-297 FORMIC ACIDtMETHYLETHYLENEACETICAMMONIAFORMATEGLYCOLANHYDRIDE\H2 \ 1 cD~_/~~;~A~~~EETHYLENEGLYCOL i\ ETHANOLSINGLE-CELLPROTEINIXYLENES 1commercial-.-.-.-- near commcrciol._-......_.....-. polenlinl (ncnl decade) Fig. 4. Commercial, near commercial and potential chemicals from synthesis gas (Wender and Seshadri,1984). Although hydrogen as such is not found in the list of top chemicals produced in theUnited States, the principal use of syngas is for the manufacture of hydrogen, hugeamounts of which are consumed in the synthesis of ammonia. The demand for hydrogencontinues to grow. Environmental concerns constitute a driving force for greater growthin the use of hydrogen to produce clean fuels and chemicals.In addition, there has been a spectacular increase in the manufacture of methanol forthe synthesis of methyl r-butyl ether (MTBE), which is used in reformulated automobilefuels. Indeed, methanol used for fuel and chemicals has achieved the status of acommodity chemical. The Fischer-Tropsch synthesis remains the third largest consumerof syngas. Sasol, using iron catalysts, continues to expand in the synthesis of fuels andchemicals from coal based syngas. In 1993, the Shell Middle Distillate Synthesis cameonstream, utilizing natural gas to produce mainly gasoline and diesel fuel in fixedtubular reactors. Plans for further growth in these newer syngas conversions arecontemplated. There is great interest in the utilization of remote natural gas reserves.Exxon has built and operated a large Fischer-Tropsch (FI’) demonstration plant usinga multiphase slurry reactor. Both the Shell and the Exxon processes are based on the useof cobalt catalysts. Both produce high molecular weight paraffins (waxes) which arehydroisomerized and cracked to liquid products suitable for refinery or chemical plantfeedstocks.Parallel with the development of the Exxon multiphase process, Sasol has developedthe so-called Sasol SPD (slurry-phase distillate) process. Until now it is the onlycommercial experience that has demonstrated successful IT slurry operation. It isdirected towards the production of paraffinic waxes; however, the product also consti-tutes a valuable feedstock for high-quality diesel fuel.
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