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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 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 temperatures are in the range of 450 to 600 °C.
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.
Natural gas has a high hydrogen to carbon ratio, so the water-gas shift is not needed for cobalt catalysts. Cobalt-based catalysts are more sensitive than their iron counterparts. Illustrative of real world catalyst selection, high-temperature Fischer–Tropsch (HTFT), which operates at 330–350 °C, uses an iron-based catalyst.
The reaction is exothermic with ΔH= -41.1 kJ/mol and have an adiabatic temperature rise of 8–10 °C per percent CO converted to CO 2 and H 2. The most common catalysts used in the water-gas shift reaction are the high temperature shift (HTS) catalyst and the low temperature shift (LTS) catalyst.
Steam can be added to the reaction in order to increase the generation of H 2, via the water-gas shift reaction (WGS) and/or steam methane reforming. The CLR process can produce a syngas with a H 2:CO molar ratio of 2:1 or higher, which is suitable for Fischer–Tropsch synthesis, methanol synthesis, or hydrogen production. The reduced oxygen ...
However, one pass through the Sabatier reactor produces a ratio of only 1:1. More oxygen may be produced by running the water-gas shift reaction (WGSR) in reverse (RWGS), effectively extracting oxygen from the atmosphere by reducing carbon dioxide to carbon monoxide.
Water-gas-shift reaction. The reaction that occurs in a water-gas-shift reactor is CO + H 2 O CO 2 + H 2. This produces a syngas with a higher composition of hydrogen fuel which is more efficient for burning later in combustion. Physical separation process.