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This is sometimes called the reverse water–gas shift reaction. [20] Water gas is defined as a fuel gas consisting mainly of carbon monoxide (CO) and hydrogen (H 2). The term 'shift' in water–gas shift means changing the water gas composition (CO:H 2) ratio. The ratio can be increased by adding CO 2 or reduced by adding steam to the reactor.
The water gas shift reaction is the reaction between carbon monoxide and steam to form hydrogen and carbon dioxide: CO + H 2 O ⇌ CO 2 + H 2. This reaction was discovered by Felice Fontana and nowadays is adopted in a wide range of industrial applications, such as in the production process of ammonia, hydrocarbons, methanol, hydrogen and other chemicals.
The reaction can be carried out over a copper-based catalyst, but the reaction mechanism is dependent on the catalyst. For a copper-based catalyst two different reaction mechanisms have been proposed, a decomposition-water-gas shift sequence and a mechanism that proceeds via methanol dehydrogenation to methyl formate.
Otherwise, sulfur-containing impurities deactivate ("poison") the catalysts required for FT reactions. [8] [7] Several reactions are employed to adjust the H 2:CO ratio. Most important is the water-gas shift reaction, which provides a source of hydrogen at the expense of carbon monoxide: [8] + +
The above reaction is actually the result of two reactions. The first reaction, the reverse water gas shift reaction, is a fast one: CO 2 + H 2 → CO + H 2 O. The second reaction is the rate determining step: CO + H 2 → C + H 2 O. The overall reaction produces 2.3×10 3 joules for every gram of carbon dioxide reacted at 650 °C. Reaction ...
Furthermore, as seen in other heterogeneous catalysts, activity increases with a decreasing diameter of supported gold clusters. Several industrially relevant processes are also observed such as H 2 activation, Water-gas shift reaction, and hydrogenation. [1] [2] [3] One or two gold-catalyzed reactions may have been commercialized. [4]
The water-gas shift reaction was discovered by Italian physicist Felice Fontana in 1780. Water gas was made in England from 1828 by blowing steam through white-hot coke.
It is possible to consume most of the CO by reacting it with steam in the water-gas shift reaction: CO + H 2 O ⇌ H 2 + CO 2. The water-gas shift reaction can reduce CO to 1% of the feed, with the added benefit of producing more hydrogen, but not eliminate it completely. To be used in a fuel cell, feed gas must have CO below 10 ppm.