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Illustrating inputs and outputs of steam reforming of natural gas, a process to produce hydrogen and CO 2 greenhouse gas that may be captured with CCS. Steam reforming or steam methane reforming (SMR) is a method for producing syngas (hydrogen and carbon monoxide) by reaction of hydrocarbons with water. Commonly, natural gas is the feedstock.
the reaction steps presented here are just a part of the reaction sequence, see reference for more details. Photocatalytic oxidation with TiO 2: [15] TiO 2 + UV → e − + h + (irradiation of the photocatalytic surface leads to an excited electron (e −) and electron gap (h +)) Ti(IV) + H 2 O ⇌ Ti(IV)-H 2 O (water adsorbs onto the catalyst ...
Hydrogen can also be produced from water and electricity using electrolysis: at one time, most of Europe's ammonia was produced from the Hydro plant at Vemork. Other possibilities include biological hydrogen production or photolysis , but at present, steam reforming of natural gas is the most economical means of mass-producing hydrogen.
The addition of hydrogen to double or triple bonds in hydrocarbons is a type of redox reaction that can be thermodynamically favorable. For example, the addition of hydrogen to ethene has a Gibbs free energy change of -101 kJ·mol −1 , which is highly exothermic . [ 11 ]
The PEM electrolyzer was introduced to overcome the issues of partial load, low current density, and low pressure operation currently plaguing the alkaline electrolyzer. [4] [1] It involves a proton-exchange membrane. Electrolysis of water is an important technology for the production of hydrogen to be used as an energy carrier. With fast ...
The pressure swing adsorption (PSA) process is based on the phenomenon that under high pressure, gases tend to be trapped onto solid surfaces, i.e. to be "adsorbed". The higher the pressure, the more gas is adsorbed. When the pressure is dropped, the gas is released, or desorbed.
These reactions were demonstrated reversible without catalysts addition at relatively low hydrogen pressure and temperatures. The addition of TiCl3 was found to decrease the working temperature of the first dehydrogenation step of 50 K, [59] but no variations were recorded for the last two reaction steps. [51]
Most important is the water-gas shift reaction, which provides a source of hydrogen at the expense of carbon monoxide: [8] H 2 O + CO H 2 + CO 2 {\displaystyle {\ce {H2O + CO -> H2 + CO2}}} For FT plants that use methane as the feedstock , another important reaction is dry reforming , which converts the methane into CO and H 2 :