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NASA is using the Sabatier reaction to recover water from exhaled carbon dioxide and the hydrogen previously discarded from electrolysis on the International Space Station and possibly for future missions. [17] [18] The other resulting chemical, methane, is released into space. As half of the input hydrogen becomes wasted as methane, additional ...
The chief use of ethane is the production of ethylene (ethene) by steam cracking. Steam cracking of ethane is fairly selective for ethylene, while the steam cracking of heavier hydrocarbons yields a product mixture poorer in ethylene and richer in heavier alkenes (olefins), such as propene (propylene) and butadiene, and in aromatic hydrocarbons.
Steam cracker process diagram Gibbs free energy per carbon atom. This shows that at high temperature, hexane can split into ethane and ethylene ("Ethen"), and ethane can split into ethylene and hydrogen. But ethylene can decompose into methane and carbon if given too much time, and all the hydrocarbons can decompose into carbon and hydrogen.
A challenge to the commercialization of this process is that the hydrogen that is produced tends to react with carbon dioxide. For example, the following reaction typically proceeds with lower activation energy than the dry reforming reaction itself: + + Another issue with dry reforming is situated in the fact that it operates at conditions ...
Autothermal reforming (ATR) uses oxygen and carbon dioxide or steam in a reaction with methane to form syngas. The reaction takes place in a single chamber where the methane is partially oxidized. The reaction is exothermic. When the ATR uses carbon dioxide, the H 2:CO ratio produced is 1:1; when the ATR uses steam, the H 2:CO ratio produced is ...
By convention, the (higher) heat of combustion is defined to be the heat released for the complete combustion of a compound in its standard state to form stable products in their standard states: hydrogen is converted to water (in its liquid state), carbon is converted to carbon dioxide gas, and nitrogen is converted to nitrogen gas.
Standard enthalpy of combustion is the enthalpy change when one mole of an organic compound reacts with molecular oxygen (O 2) to form carbon dioxide and liquid water. For example, the standard enthalpy of combustion of ethane gas refers to the reaction C 2 H 6 (g) + (7/2) O 2 (g) → 2 CO 2 (g) + 3 H 2 O (l).
In its simplest form, an oxygen-carrying species (normally a metal) is first oxidized in the air forming an oxide. This oxide is then reduced using a hydrocarbon as a reducer in a second reaction. As an example, an iron based system burning pure carbon would involve the two redox reactions: