Methane

 

Methane

Chemical formula	{{#Chem:CH4}}
OTP appearance	clear, odorless gas
Molar Mass(g/mol)	16
Density(g/cc)	0.6556
Melting Point(°C)	-182
Boiling Point(°C)	-164
Fuel Value(MJ/kg)	47.1
Speed of sound 20°C, 1atm (m/s)	446
NFPA 704	4 1 0

Uses

Primary

• Definitive C₁ compound
• Feedstock for chloromethane production or methanol

Other

• Fuel
• Feedstock for producing hydrogen.

Natural occurrence

• Methane occurs naturally in the presence of decaying biological materials.
  • 1kg biowaste through a digester (10-40 days) produces 1m³ of methane ~= 6kWh = 21.6MJ

Hazards

• Fire and explosion
• Asphyxiant

Production

Biologic

Anaerobic decomposition of biowaste in a digester results in the production of methane.

Synthesis

alkali degradation

• Combine sodium acetate and sodium hydroxide

  {{#Chem: CH3COONa + NaOH { = heat} CH4 + Na2CO3}}

• Combine propanone and calcium hydroxide

  {{#Chem: C3H6O + Ca(OH)2 --> 2 CH4 + CaCO3}}

hydrogenation

of carbon monoxide

The Sabatier reaction hydrogenates carbon monoxide as feedstock and produces water as well as methane.

{{#Chem: CO + 2 H2 { Ni → 1atm, 200-300°C } CH4 + H2O}}

of carbon dioxide

Similar to Sabatier (above), hydrogenation of carbon dioxide produces water as well as methane

{{#Chem: CO2 + 4 H2 { Ni → 1atm, 200-300°C } CH4 + 2 H2O}}

• Urushibara nickel is a popular choice of catalyst, at temperatures of 350°C and above atmospheric pressure
• The reaction can be carried out at OTP using Ruthenium oxide / Titanium oxide catalysts, particularly with photoexcitation.

of hydrocarbons

Larger hydrocarbons can be hydrogenated (usually over a catalyst like Urushibara nickel) into methane:

• Acetylene

  {{#Chem: HCCH + 3H2 = 2CH4}}

• Pentane

  {{#Chem: C5H12 + 4H2 = 5CH4}}

See also

• Compost
• Lunde, Peter J.; Kester, Frank L. "KINETICS OF CARBON DIOXIDE METHANATION ON A RUTHENIUM CATALYST"
  Hamilton Standard
  link courtesy Argonne National Laboratory.