What is Hydrogen?
Universally, Hydrogen is the most abundant element. The Sun and the other stars are composed of hydrogen mainly. According to their estimation, Astronomers, 90% of the atoms in the universe, are hydrogen atoms. Hydrogen is the component comprised of more compounds compared to any other element. Also, water is the most abundant hydrogen compound that is found on Earth. Hydrogen is also an essential part of petroleum, many minerals, sugar, fats, cellulose and starch, oils, acids, alcohols, and thousands of other substances.
Hydrogen is a colorless, tasteless, odorless, and nonpoisonous gas at ordinary temperatures consisting of the diatomic molecule H2. Since hydrogen forms covalent compounds with most nonmetallic elements readily, most of the hydrogen element on Earth exists in molecular forms like water or organic compounds.
Hydrogen Preparation Methods
Preparation of Hydrogen involves multiple steps. Hydrogen is a unique element because it shows resemblance to both halogens and alkali metals. It is a reactive element and forms many hydrides and other compounds. It is found in a considerable amount in the plant and animal tissues. The hydrogen preparation methods can be given broadly as,
Preparation of Hydrogen by Laboratory method
Preparation of Hydrogen by a commercial preparation method
Industrial preparation of Hydrogen
1. Preparation of Hydrogen by Laboratory Method
The laboratory preparation of Hydrogen can be explained briefly as below.
This is a method of preparation of hydrogen that is used frequently. Hydrogen is produced when granulated zinc is reacted with dilute hydrochloric acid. This is a general procedure for producing hydrogen. Besides, hydrogen can also be prepared by reacting zinc with aqueous alkali. The following reaction explains it by making this clear.
Zn + 2NaOH --> Na2ZnO2 + H2
2. Preparation of Hydrogen by a Commercial Preparation Method
There are different ways in which hydrogen is prepared commercially, and this is another method of preparation of hydrogen. The following are some of the generalized methods used.
Hydrogen is produced when the acidified water is electrolyzed by using the platinum electrodes.
To obtain high purity hydrogen, we can electrolyze the warm aqueous barium hydroxide solution between the nickel electrodes.
Hydrogen is also formed when the stream reacts with hydrocarbons at specifically high temperatures in the presence of some catalyst. For example, methane reacts with water at 1270K in the presence of nickel to produce carbon monoxide and water.
CH4 (g) + H2O(g) --> CO(g) + 3H2(g)
The carbon monoxide and water mixture are popularly known as water gas. This water gas is used in synthesizing methanol and many hydrocarbons, and thereby, it is also referred to as 'syngas' or synthesis gas. This synthesis gas is prepared from sewage, scrap wood, sawdust, and the related materials. We can also make syngas from coal, and this process is called 'coal gasification.' The increase of the production of hydrogen gas can be done by reacting carbon monoxide of synthesis gas with a stream in the presence of iron chromate as a catalyst at a temperature of up to 673K.
CO(g) + H2O(g) → CO2(g) + H2O(g)
The above-given reaction is known as the water-gas shift reaction. Currently, the maximum percentage of the hydrogen gas is formed from petrochemicals, some from coal, and a tiny percent from the electrolysis of an aqueous solution.
3. Industrial Preparation of Hydrogen
An essential industrial method for the production of hydrogen is the catalytic steam-hydrocarbon process. The gaseous or vaporized hydrocarbons are treated with steam at high pressure over a nickel catalyst at 650°- 950° C to form carbon oxides and hydrogen.
CnH2n+2 + nH2O ---> nCO + (2n + 1)H2; CnH2n+2 + 2nH2O ---> nCO2 + (3n + 1)H2
The primary reaction products are further processed in different ways based on the hydrogen's desired application. One more important hydrogen production process is the noncatalytic partial oxidation of hydrocarbons under elevated pressures.
CnH2n+2 + (n/2)O2 ---> nCO + (n + 1)H2
This process needs a feed system for delivering accurate oxygen and fuel rates, individual design burners to give rapid mixing of the reactants, a cooling system, and a refractory-lined reactor to recover heat from the effluent gases. The latter process is exothermic (producing heat) compared to the endothermic (absorbing heat) steam-hydrocarbon process.
1. Mention Some Hydrogen Uses?
There are many hydrogen uses and some of them are given here. Hydrogen is used in the conversion of heavy fractions of petroleum into lighter fractions passing through hydrocracking. Also, it is used in other processes, including the hydrodesulfurization, aromatization, and ammonia production through the Haber process.
Hydrogen is also used in fuel cells for local electricity generation or as a transportation fuel potentially.
It is produced as a by-product of industrial chlorine production using electrolysis. Although requiring expensive technologies, hydrogen can be compressed, cooled, and purified for usage in other processes on the sites or sold to a customer via pipeline, trucks, or cylinders. The discovering and development of less expensive methods of production of bulk hydrogen are relevant to the establishment of a hydrogen economy.
2. Explain the Commercial Preparation of Hydrogen Method?
The commercial preparation of hydrogen is a big industry because there is an excessive demand for hydrogen in the fertilizer production and oil-refining process.
Electrolysis of Water
This is one of the commercial preparation of hydrogen methods that helps in producing a very pure form of hydrogen from water. Electricity passes through the water breaking the water molecules. The oxygen collects at the anode while the hydrogen collects at the cathode.
In this process, the Water Gas (a mixture of hydrogen and carbon monoxide) and steam are passed alternatively over iron at very high temperatures ranging up to 800° C. First, the iron is oxidized, releasing hydrogen and has to be replaced with new metal. Later, the iron reduces with water gas back to metal. The reactions are represented as follows
3Fe + 4H2O → Fe3O4 + 4H2
Fe3O4 + 4CO ---> 3Fe + 4CO2
The net reaction occurred is
CO + H2O ---> CO2 + H2
From Natural Gas
This is the cheapest way to produce hydrogen on a commercial scale. The natural gas is heated to high temperatures (to a maximum of 1100° C) with a nickel catalyst and steam. This results in the methane molecules breaking into Hydrogen and Carbon Monoxide.
CH4 + H2O ---> CO + 3H2