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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.
Water gas is a kind of fuel gas, ... For example, James Lind recognized ... The process used the water-gas shift reaction: CO + H 2 O → CO 2 + H 2.
Water-reactive substances [1] are those that spontaneously undergo a chemical reaction with water, often noted as generating flammable gas. [2] Some are highly reducing in nature. [ 3 ] Notable examples include alkali metals , lithium through caesium , and alkaline earth metals , magnesium through barium .
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.
At the positively charged anode, an oxidation reaction occurs, generating oxygen gas and giving electrons to the anode to complete the circuit. The two half-reactions, reduction and oxidation, are coupled to form a balanced system. In order to balance each half-reaction, the water needs to be acidic or basic.
The reaction of CO 2 with carbon to give CO is described as the Boudouard reaction. [66] Above 800 °C, CO is the predominant product: CO 2 (g) + C (s) → 2 CO (g) (ΔH r = 170 kJ/mol) Another source is "water gas", a mixture of hydrogen and carbon monoxide produced via the endothermic reaction of steam and carbon:
A variety of synthesis-gas compositions can be used. For cobalt-based catalysts the optimal H 2:CO ratio is around 1.8–2.1. Iron-based catalysts can tolerate lower ratios, due to the intrinsic water-gas shift reaction activity of the iron 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.