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Paschen's law is an equation that gives the breakdown voltage, that is, the voltage necessary to start a discharge or electric arc, between two electrodes in a gas as a function of pressure and gap length. [2] [3] It is named after Friedrich Paschen who discovered it empirically in 1889. [4]
Liquid hydrogen (H 2 (l)) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H 2 form. [4] To exist as a liquid, H 2 must be cooled below its critical point of 33 K. However, for it to be in a fully liquid state at atmospheric pressure, H 2 needs to be cooled to 20.28 K (−252.87 °C; −423.17 °F). [5]
Isotherms of an ideal gas for different temperatures. The curved lines are rectangular hyperbolae of the form y = a/x. They represent the relationship between pressure (on the vertical axis) and volume (on the horizontal axis) for an ideal gas at different temperatures: lines that are farther away from the origin (that is, lines that are nearer to the top right-hand corner of the diagram ...
High pressure is necessary to ensure sufficient surface coverage of the catalyst with nitrogen. [56] For this reason, a ratio of nitrogen to hydrogen of 1 to 3, a pressure of 250 to 350 bar, a temperature of 450 to 550 °C and α iron are optimal. The catalyst ferrite (α-Fe) is produced in the reactor by the reduction of magnetite with ...
The catalytic performance of Mo3P nanoparticles is tested in the hydrogen evolution reaction (HER), indicating an onset potential of as low as 21 mV, H2 formation rate, and exchange current density of 214.7 μmol/(s·g) cat (at only 100 mV overpotential) and 279.07 μA/cm 2, respectively, which are among the closest values yet observed to platinum.
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 production of natural gas feedstock also produces emissions such as vented and fugitive methane, which further contributes to the overall carbon footprint of hydrogen. [119] This reaction is favored at low pressures, Nonetheless, conducted at high pressures (2.0 MPa, 20 atm or 600 inHg) because high-pressure H 2 is the most marketable ...
The Fischer–Tropsch process (FT) is a collection of chemical reactions that converts a mixture of carbon monoxide and hydrogen, known as syngas, into liquid hydrocarbons. These reactions occur in the presence of metal catalysts , typically at temperatures of 150–300 °C (302–572 °F) and pressures of one to several tens of atmospheres.