Synthesis Gas Manufacture

Most syngas is produced captively for the manufacture of methanol from natural gas. Natural gas is reformed with steam to produce a raw syngas which enters a methanol synthesis reactor and is converted directly to methanol. Methanol is not regarded as a petrochemical, as it is usually produced from natural gas rather than a petroleum-derived hydrocarbon, but it is used as feedstock to produce a great many petrochemicals. Syngas is also used as feedstock in the 0x0 process to produce a wide variety of aldehydes and alcohols. 

Pure hydrogen is used in a great many petrochemical processes. The largest amount is used to produce ammonia. Ammonia, like methanol, is not a petrochemical, but it plays a prominent role in the synthesis of a great many petrochemicals. Ammonia is used primarily to manufacture 

Carbon monoxide is purified and used as a feedstock for several primary petrochemicals The largest quantity is used for carbonylation of methanol to produce acetic acid. Acetic acid is used in the production of vinyl acetate, acetic anhydride and cellulose acetates. Phosgene, formed by the reaction of carbon monoxide with chlorine, is reacted with amines to form polyurethane intermediates. Phosgene is also reacted with bisphenol A to form polycarbonate resins, used for engineering plastics. 

Petrochemical applications of syngas require a ratio of hydrogen to carbon monoxide of either 1 1 or 2 1. Commercial processes for syngas yield ratios much higher therefore, separation technology, by-product credits and production techniques which can adjust the hydrogen to carbon monoxide ratio are important aspects of syngas production. 

Partial oxidation of hydrocarbons can also be used to produce synthesis gas. Partial oxidation, when used for conversion of a solid such as coal or petroleum coke, is generally referred to as gasification. When applied to gaseous or liquid feeds, it is usually called partial oxidation (POX). In principle, however, the two processes are essentially the same. Gasification or partial oxidation takes place at high temperature and pressure in the presence of a small amount of steam and either air or pure oxygen. High 

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They used a Ni-containing catalyst. In contrast to steam reforming of methane, methane partial oxidation is exothermic. However, the partial oxidation requires pure oxygen, which is produced in expensive air separation units that are responsible for up to 40% of the cost of a synthesis gas plant (2) (in contrast, the steam reforming process does not require pure oxygen). Therefore, the catalytic partial oxidation of methane did not attract much interest for nearly half a century, and steam reforming of methane remained the main commercial process for synthesis gas manufacture. 

Synthesis gas manufacture by partial oxidation or autothermal cracking of crude oil fractions was developed by BASF/Lurgi, Texaco and Hydrocarbon Research. Heat for the thermal cracking is supplied by partial combustion of the feed in the presence of water. Recycled CO2 may also be added to the combustion to attain a desired CO/H2 ratio46. 

The first U.S. manufacturer to produce a slate of industrial chemicals from coal was Eastman Chemical Company (Division of Eastman Kodak Company). Commercial facilities include a coal gasification plant for synthesis gas manufacture, raw gas cleanup... 

Garvie, J. H. (November 1967) Synthesis gas manufacture. Chem Proc Engng, pp. 55-65. 

Gasoline and distillate fuels can be produced via methanol as illustrated schematically in Fig. 1. Synthesis gas can be manufactured from natural gas by steam reforming, or from coal by partial oxidation. Since synthesis gas manufacture, and methanol synthesis, represent the largest cost in synthetic fuels production, considerable effort has been dedicated to improving... 

It is not the object of this paper to summarize again all the literature. It would also be beyond the scope to discuss in detail industrial and engineering features of hydrocarbon synthesis, as well as questions which are only indirectly connected with the synthesis such as synthesis gas manufacture or conversion of primary synthesis products to other compounds. The scope of this paper inevitably limits the review to important steps of research work on the reactions of carbon monoxide and hydrogen, with special consideration regarding the behavior of the catalysts necessary to carry out the reactions. 

Figure 11. Synthesis Gas Manufacture in "State-of-the-Art" Ammonia Process Front-end (Dybkjaer, 1990).

Figure 12. Synthesis Gas Manufacture in Methanol Plant. Two Step Reforming.

Commercial facilities constructed include a coal gasification plant for synthesis gas manufacture, raw gas cleanup and separation facilities, a sulfur recovery unit, a coal-fired steam plant, and chemical plants to produce methanol, methyl acetate, acetic acid, and acetic anhydride. In the 1980s, these plants gasified approximately 900 tons of coal/day to produce annually over 500 million lb of acetic anhydride, 150 million lb of acetic acid, 390 million lb of methyl acetate, 365 million lb of methanol, and 15 million lb of sulfur. An expansion in 1991 more than doubled the capacity for methyl acetate, acetic acid, and acetic anhydride. Approximately one billion lb of acetic anhydride, one of Eastman s key raw materials, is used each year in making photographic film base, Tenite cellulosic plastics, Estron acetate for filter tow, textile yarns, and coatings chemicals. 

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