Synthesis gas reaction

Oxo Synthesis. Ad of the synthesis gas reactions discussed to this point are heterogeneous catalytic reactions. The oxo process (qv) is an example of an industriady important class of reactions cataly2ed by homogeneous metal complexes. In the oxo reaction, carbon monoxide and hydrogen add to an olefin to produce an aldehyde with one more carbon atom than the original olefin, eg, for propjiene ... 

Obviously, the reaction network of the synthesis gas is very versatile and only the rather high cost of syngas itself prevents its wide application. When CO conversion was introduced into industrial practice, coal was the main source of CO/H2. Nowadays, it is mainly CH4 from remote gas fields. Synthesis gas reactions are also a very suitable subject for courses on catalysis. Many interesting aspects of the mechanism, kinetics and technology can be demonstrated using the data available for this reaction. 

By far the most important synthesis gas reaction is its conversion into methanol, using copper/zinc oxide catalysts under relatively mild conditions (50 bar, 100-250°C). Methanol is further carbonylated to acetic acid (see Section 22-7), so that CH3C02H, methyl acetate, and acetic anhydride can all be made from simple CO and H2 feedstocks. Possible pathways to oxygenates in cobalt catalyzed reactions are shown in Fig. 22-6. 

The homologation of methanol has been proved to be a most promising process for the production of oxygenated Cj chemicals. A survey of the recent literature demonstrates the considerable efforts to improve yields and selectivilies of this synthesis gas reaction. The complex influence of catalyst composition and reaction conditions has been empltasizcd, and although the course of the reaction is not fully understood, recent results suggest a mechanistic pattern similar to that of methanol carbonylation. 

The synthesis gas reaction (I) is limited to an equilibrium and is therefore run in the presence of an excess of water, which has another beneficial role that of reducing the carbon formation on the catalyst. As reaction (1) produces too much hydrogen fur the methanol synthesis ( ). the process may be operated in the presence of CO2. in order to adjust the gas composition (5) ... 

Two types of reduction reactions will be treated. The synthesis gas reaction (Section 5.2) in which CO is reduced by hydrogen shows a rich spectrum of products and is becoming of increasing importance as a reaction step in the transformation of natural gas to chemical products. 

Natural gas is reacted in a similar manner as gasification of solid hydrocarbons. Methane, the primary component of natural gas, is reacted with steam over a nickel-on-alumina catalyst at 750-800°C to produce synthesis gas (Reaction 9). 

The reaction is catalyzed by Co carbonyls using reaction conditions in the range 200-250 bar and 175-210°C, and, when first reported, was characterized by both low yields (maximum 42%) and a spectrum of by-products including acetaldehyde, methyl formate, methyl acetate, propanol, butanol, and methane (17). Subsequently, catalytic activity toward hydrocarbonylation has been demonstrated with other metals, although Rh, usually appreciably more active than Co in other synthesis gas reactions, produces acids and esters, and ethanol only comprises a significant product at high H2 partial pressures. Methanol hydrocarbonylation may also be carried out with Fe or Ru catalysts promoted by tertiary amines, but the rates are even lower than with Co, which remains the preferred choice. The reaction rate is accelerated by the presence of promoters such as I , in which case acetaldehyde (which may also be obtained from the Co/I -catalyzed reaction of synthesis gas with methyl ketals or methyl esters (18)), comprises the major product. 

Catalysts, which will allow operating at more severe process conditions, are expected to improve the technology as well. For example, development of coke-resistant catalysts for IHSR that are based on noble metals, can allow operating the synthesis gas reaction at much lower steam ratios (58). 

Appendix 1 shows the coefficients in the enthalpy polynomials for a number of characteristic synthesis gas reaction key components and a table with actual values of the ideal enthalpies of formation as a function of temperature. 

This process, called hydrogenation, is used in the food processing industry whoe oils (liquids) that contain many carbon-carbon double bonds are converted to fats (solids) that contain few or no carbon-carbon double bonds. AnothCT important process that requires hydrogen is the cobalt-catalyzed synthesis gas reaction with carbon monoxide to produce methyl alcohol. 

Synthesis gas reaction a chemical reaction in which a mixture of CO and H2 gases is used in the industrial preparation of a number of organic compounds, including methanol, CH3OH. (p. 923) System (thermodynamic) the substance or mixture of substances under study in which a change occurs. (6.2)... 

Olsbye, U., Moen, O., Slagtern, A., et al. (2002). An Investigation of the Coking Properties of Fixed and Fluid Bed Reactors during Methane-to-Synthesis Gas Reactions, Appl. Catal. A Gen., 228, pp. 289-303. 

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