Hydrogen production carbon monoxide shift

Study of the mechanism of this complex reduction-Hquefaction suggests that part of the mechanism involves formate production from carbonate, dehydration of the vicinal hydroxyl groups in the ceUulosic feed to carbonyl compounds via enols, reduction of the carbonyl group to an alcohol by formate and water, and regeneration of formate (46). In view of the complex nature of the reactants and products, it is likely that a complete understanding of all of the chemical reactions that occur will not be developed. However, the Hquefaction mechanism probably involves catalytic hydrogenation because carbon monoxide would be expected to form at least some hydrogen by the water-gas shift reaction. 

In conventional production of hydrogen from coal, as described earlier, coal is converted to hydrogen and carbon monoxide (CO) through the water-carbon reaction as shown in reactions 3.9 through 3.11. CO is then converted to hydrogen and carbon dioxide by the water-gas shift reaction as shown in reaction 3.12. 

Although the reaction given is for methane, other hydrocarbons can be substituted instead and the products remain hydrogen and carbon monoxide. The carbon monoxide can be further reacted with water via the water-shift reaction ... 

In fact, moisture appears to play a more integral role in the combustion of hydrogen-deficient carbonaceous fuels (such as coal) than has been generally recognized. The carbon-steam reaction to produce carbon monoxide and hydrogen (which are then oxidized to the final products) is an important stage in the combustion sequence as is the carbon monoxide shift reaction to yield carbon dioxide and hydrogen ... 

Water-Gas Shift Reaction Cataiyzed by Metai Oxides. Before the use of the WGS reaction to produce hydrogen from carbon monoxide and water, the production of hydrogen was achieved from the addition of metallic iron to strong acids or from the electrolysis of water (219). The first report of the WGS reaction was published in 1888 (220) and described how the passage of carbon monoxide and water vapor over red-hot refractory material produced carbon dioxide and hydrogen ... 

Measurements of conversions at CPO conditions reported in the literature are seldom showing conversions relative to the equilibrium conversions. Yields are often expressed as selectivities to hydrogen and carbon monoxide although the product gas in most situations is close to equilibrium for the reforming and shift reactions. Therefore selectivity data should be supplemented by calculation of approach to equilibrium, ATref (Equation 1.11). Reported selectivities may be misleading. Even sophisticated catalyst compositions lead to equilibrated product gas as illustrated in Example 1.4 below. 

The product mixture of the reaction is known as the reformate. The reaction is endothermic and thus requires a heat supply. Besides hydrogen and carbon monoxide, the reformate usually contains significant amounts of unconverted steam, and to a lesser extent some unconverted fuel and carbon dioxide, the latter being formed by the consecutive water-gas shift reaction ... 

Notice that due to high operating temperatures, a variety of other processes such as reforming of hydrocarbons, carlxMi oxidation, and water gas shift reaction may also occur at the anode. The inverse electrode reactions occur in the solid oxide electrolysis cells (SOECs) used to cOTivert steam and carbon dioxide into hydrogen and carbon monoxide, respectively. The operation of the electrochemical reactors with SE membranes, which can also be used to cogenerate electricity and valuable chemical products, is typically based on incomplete oxidation or reduction of the reactants as an example, synthesis gas can be produced in SOFCs via the partial oxidation of methane (POM) ... 

The hydrogen-to-carbon monoxide mole ratio for the product gas is usually 4 to 9 however, it can be increased if additional steam is used in the reaction. This will reduce the demand in the carbon monoxide-shift converters, which follow the secondary reformer. Steam sometimes is introduced after the reformer before the gas is fed to the carbon monoxide-shift converters. In the single-train ammonia plants, the natural gas is reformed in two steps. In the first step, the reaction takes place in the primary reformer in tubes suspended in a refractory-lined furnace. The large amount of endothermic heat is supplied by burning natural gas with air in the furnace. The heat flux in the tubes can be as high as 35,000 Btu/hr sq ft. The methane leakage is about 10 percent in the effluent dry gas, or about 60 to 65 percent of the feed methane is converted to synthesis gas. 

Prior to methanation, the gas product from the gasifier must be thoroughly purified, especially from sulfur compounds the precursors of which are widespread throughout coal (23) (see Sulfurremoval and recovery). Moreover, the composition of the gas must be adjusted, if required, to contain three parts hydrogen to one part carbon monoxide to fit the stoichiometry of methane production. This is accompHshed by appHcation of a catalytic water gas shift reaction. 

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