HOW HYDROGEN IS OBTAINED

          The Production of Hydrogen

Decomposition of Certain Hydrocarbons with Heat:

The catalytic action of steam on hydrocarbons makes up the largest production of hydrogen. The general actions provided by World Book are:

C_nH_2n+2 + nH₂O --> nCO + (2n+I) H_{2 and}

C_nH_{2n+2 +} 2nH₂O _--> nCO_{2 +} (3n+I)H₂

_{Example Reaction between methane and water: CH4(g) + H2O(g) --> 3 H2(g) + CO(g)}

The temperature range of each reaction varies with the catalyst. Alumina (bauxite) has it's temperatures as lows as 77* F with propane as the hydrocarbon. 95% of the Carbon Monoxide (CO) produced by the reaction is converted into hydrogen and carbon dioxide by the use of steam in another reaction:

H₂O + CO---> CO₂ + H₂

Displacement of Acids by Certain Metals:  

_{Click Here to See the Displacement of HCl and HNO3 by Zinc}

Small quantities of Hydrogen gas are obtained through the addition of zinc or iron filings to a test tube containing hydrochloric acid. The bubbles given off are Hydrogen gas. Manufacturing plants and laboratories use cylinders of the compressed gas when large amounts of Hydrogen are needed (Stwertka,17).

        Zn + 2 HCl -->H₂(g) + ZnCl₂

Water Decomposition:

• Commercially prepared Hydrogen is prepared by decomposing water. This famous reaction called the, “water gas reaction,” is when steam passes over hot carbon in the form of coke, with methane gas sometimes acting as the substitute for coke. The, “water gas reaction,” involving water in the form of superheated steam and methane, CH₄ and water, H₂0 frees molecules forming hydrogen gas. 

               CH₄(g) + H₂O(g) --> 3 H₂(g) + CO(g)

Steam on Heated Carbon: C(s) + H₂O(g) --> H₂(g) + CO(g)

• When the water gas reaction involves coke at temperatures at 1,000* C, carbon monoxide (CO), carbon dioxide and a small amount of hydrogen gas are released from the coke. The carbon monoxide and hydrogen may be physically separated, but often are used in combination with each other referred as the, “water gas.” This “water gas” is then put to use as an industrial fuel. With further treatment of steam at 700*F, CO can be removed to form more H₂ and CO₂. Through a process of using counter-current water scrubbers or towers in which the gas stream is washed by water running in the opposite direction, carbon dioxide can be easily removed (431).

Electrolysis Procedure:

Electrolysis Procedures make up the third-largest source of hydrogen production. Electrolysis involves separating the atoms of Hydrogen and Oxygen from the molecule H₂O or water by charging water with an electrical current. 

2 H₂O(liq) + electrical energy --> 2 H₂(g) + O₂(g)

A salt such as Sodium Hydroxide may be used to improve the conductivity of the water, thus making the process more efficient. Hydrogen and Oxygen may be yielded by electrolyzing Water with small concentrations of NaOH at approximately 2 volts using nickel anodes and iron cathodes at 80* C (431). 

2H₂O(g) ---NaOH> 2H_2(g) +O₂(g)

In order for 1,000 standard cubic feet of hydrogen to be produced, 150 kilowatt hours would need to be expended and seven gallons of water would need to be electrolyzed (431).

Action of Sodium or Potassium Hydroxide on Aluminum:

Click here to see this reaction taking place

Al + NaOH --> H₂(g) + Al(OH)₃

Biological and Photo biological Processes:

Bacteria and certain types of algae or used to produce hydrogen.  An enzyme in the pigment of certain algae that absorbs the sun's solar energy, acts as a catalyst in splitting water molecules. The bacteria that produce hydrogen produce hydrogen in the same way algae do, but they differ in that bacteria need a substrate to grow on (Corrosion- Doctors).