Hydrogen production, with ever more numerous and tried and found techniques to be able to create an alternative to the more classic and not very environmentally friendly ones. There Hydrogen production from methane it is increasingly popular even if it cannot be defined as a widespread technique. We begin to know it and explore the context in which it fits, ready to know its future successes.
To date we have to admit that in most cases the hydrogen production takes place starting from hydrocarbons and fossil fuels, through a chemical process. In fact, it can also be obtained from water through organic production in bioreactor algae, or with processes such as electrolysis or thermolysis.
Today these methods are not yet as efficient as those that see hydrocarbons as protagonists but the developments are fast and interesting, they require funds, as well as knowledge and time, but what is commonly called hydrogen economy will reserve us some very green surprises.
Hydrogen production from methane (steam methane reforming)
When it comes to steam reforming we mean the process that, especially in the industrial field, leads to the production of syngas. In general we start from hydrocarbons but since we are talking about steam methane reforming, it is clear that we must refer only to methane, the protagonist of the reaction together with water vapor.
We can consider it divided into two phases, and we find it in the synthesis of methanol, it occurs in a similar way also for ammonia. The first phase, also called Primary reforming, it is endothermic, occurs at a high temperature: 700 ° C are the ones that favor this reaction. In the second part, also called secondary reforming, yes the gas mixture obtained, containing residual methane (CH4), carbon monoxide (CO), water (H2O) and hydrogen (H2), which becomes the protagonist of a post-combustion. It occurs with the use of air and allows to obtain a higher concentration of carbon monoxide and hydrogen and a lower concentration of residual methane.
It is no coincidence that he speaks of air and not pure oxygen, (O2), in this mode of Hydrogen production from methane: since it is an exothermic reaction, with pure oxygen it would reach too high temperatures, also taking into account the fact that it starts from about 900 ° C, and from a not very high residual methane concentration. During the Hydrogen production from methane supported nickel is used as catalyst.
Hydrogen production from methane: costs
Today this process does not have competitive costs, the cheapest one for Hydrogen productioninvolves the use of oil or other fossil fuels. Almost all of the hydrogen comes from fossil fuels, a few percentage points instead from the electrolysis of water, the remaining methods remain and are the subject of studies but we must also go a long way to reduce costs and in some cases optimize the Phase-by-phase hydrogen production.
Similar to the Hydrogen production from methane, there is the one related to synthesis of ammonia, also known as the Haber-Bosch process, in this case we start from natural gas, with an approximate efficiency of 80%.
Hydrogen production or steam reforming
From methane or not, the Hydrogen production starting from natural gas or "steam reforming", requires a reaction in which water vapor appears and which takes place at a temperature that can vary in the case of gas in gas, from 700 to 1100 ° C. In this way one gets mixture consisting essentially of carbon monoxide and hydrogen, called syngas, provided you provide the heat required to activate the reaction. It is obtained by burning part of methane or other hydrocarbons, the proportions with which the various substances are then combined in the obtained Syngas are variable.
Hydrogen production by electrolysis
We mentioned theelectrolysis for hydrogen production, a process that manages to provide us with about 3% of the hydrogen used today. If we do not know how the processes that exploit fossil fuels dominate, with consequent emission of large quantities of CO2, this about 3% may seem little to us. Instead, it is a percentage that makes electrolysis the only process that has some practical relevance and a near future that can make us smile.
For electrolysis to occur, electricity is required, necessary to break down water into its two elements H and O and no fossil products are required. That's why we talk a lot and a lot focuses on the "Hydrogen Economy", hoping the time will soon come when the hydrogen production takes place starting from renewable sources.
Always harboring hopes and believing in those who are carrying out research on electrolysis, we take into account the fact that, if implemented with an anodic electrolyser, it also provides "by-products ”which have a commercial value in the cosmetics sector e in the textile industry, as well as in the food industry and for the production of biodegradable plastics.
Hydrogen production from water
There Hydrogen production from water, also called electrolysis of water, is quite simple and requires low voltage current. It crosses the water and forms gaseous oxygen at the anode and gaseous hydrogen at the cathode, usually the latter is made of platinum, or another inert metal. However, it is necessary that both the electrodes, anode and cathode, are of an inert metal, in the event that the hydrogen produced must be consumed "in situ", because the presence of oxygen would become necessary so that there is combustion and both electrodes.
If iron or another non-inert metal was used, it would oxidize with a decrease in the amount of oxygen that develops). Efficiency, the theoretical maximum, of electrolysis from water, is around 80-94%.
Hydrogen production at home
While we wait to read the overtaking of green methods in the Hydrogen production, in our own small way we can dedicate ourselves to do-it-yourself methods starting from water and exploiting the chemical reactions in which we tear the two hydrogen atoms from the water molecule. Let's roll up our sleeves and read how to proceed in the article "How to produce hydrogen from water”.
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