Complete Ultra-Detailed English Product Document – Methane (CAS 74-82-8)
1. Full Basic Identification & Registry Data
Core Identity
- CAS No.: 74-82-8
- Chemical Name: Methane
- IUPAC Name: Methane
- Common Aliases: Marsh Gas, Methyl Hydride, Refrigerant R50, Compressed Methane, Cryogenic Liquid Methane
- EINECS / EC No.: 200-812-7
- EC Index No.: 601-001-00-4
- MDL No.: MFCD00008279
- Molecular Formula: \(\boldsymbol{CH_4}\)
- Structural Formula: Tetrahedral single carbon fully saturated with four hydrogen atoms
- SMILES: C
- InChI: 1S/CH4/h1H4
- InChI Key: VNWKTOKETHGBQD-UHFFFAOYSA-N
- Molecular Weight: 16.04 g/mol
- UN Transport Codes:
- UN 1971: Methane, Compressed (CNG / high-pressure cylinder gas)
- UN 1972: Methane, Refrigerated Cryogenic Liquid (LNG pure methane grade)
- HS Customs Code: 27112100 (compressed methane); 27111100 (cryogenic liquid methane)
- Hazard Class & Packing Group: Class 2.1 Extremely Flammable Compressed Liquefied Gas, Packing Group I
- REACH Status: Exempted from full REACH registration as pure simple alkane industrial gas
- National Hazard Code (China): 21007
2. Comprehensive Physical Properties (Full Tabulated Precision Data)
Macro Appearance
- Ambient pressure (25 ℃, 1 atm): Colorless, completely odorless transparent gas; commercial fuel-grade adds mercaptan odorant (rotten egg smell) for leak detection
- Cryogenic state (-161.5 ℃, 1 atm): Transparent, low-viscosity colorless liquid
- Solid state (-182.5 ℃): White crystalline ice-like solid
Quantitative Physical Constant Table
| Parameter | Exact Numerical Value | Supplementary Note |
| Melting Point (1 atm) | -182.5 ℃ / -296.5 ℉ | Solid-liquid equilibrium |
| Boiling Point (1 atm) | -161.5 ℃ / -258.7 ℉ | Rapid vaporizes at room temp once pressure released |
| Critical Temperature | -82.59 ℃ | Above this temp cannot liquefy by pressure alone |
| Critical Pressure | 4.599 MPa | 45.4 atm |
| Liquid Density (-161.5 ℃) | 0.422 g/cm³ | Lighter than water |
| Gas Density (25 ℃, 1 atm) | 0.716 g/L | Air = 1.225 g/L; methane vapor density = 0.55 vs air |
| Relative Vapor Density (Air=1) | 0.55 | Lighter than air, gas rises and disperses upward |
| Closed-Cup Flash Point | -188 ℃ / -306 ℉ | Ultra-low flash point, instantly flammable at all ambient temperatures |
| Autoignition Temperature | 595 ℃ / 1103 ℉ | Requires strong ignition source; no spontaneous ignition at normal industrial temp |
| Flammable Explosion Limit in Air (V/V) | LEL = 5.0 % ; UEL = 15.0 % | Very wide explosive range, high risk in confined spaces |
| Heat of Combustion (Net Calorific Value) | 802.3 kJ/mol / 35.8 MJ/m³ | Clean blue flame, low carbon emission |
| Vapor Pressure (20 ℃) | 258,574 mmHg | Extremely volatile under atmospheric pressure |
| Water Solubility (25 ℃, 1 atm) | 24.4 mg/L | Practically insoluble in water |
| Organic Solvent Solubility | Fully miscible with ethers, light alkanes, toluene, benzene; slightly soluble in methanol/ethanol | No reaction with inert hydrocarbon solvents |
| Refractive Index (gas, 20 ℃) | 1.0004 | Near identical to air |
| pKa (gas phase) | 48 | Extremely weak acid, no ionization in water |
| Flame Color | Pale light blue, nearly smokeless | Complete clean combustion without soot |
Special Physical Hazards
- Cryogenic liquid direct skin contact causes severe frostbite due to massive endothermic vaporization
- High-pressure gas release creates static charge, ignition risk
- Low density means gas accumulates under ceiling/roof of enclosed buildings, hard to vent fully
3. Complete Chemical Properties & Reaction Mechanisms
Core Structural Feature
Methane is the simplest saturated aliphatic alkane with zero functional groups, fully saturated single C-H bonds, chemically inert under normal ambient temperature without catalyst.
1. Combustion Reaction (Most Common Industrial Reaction)
- Complete combustion (sufficient oxygen):
\(CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O + Heat\)
Clean, low-pollution, primary energy reaction
- Incomplete combustion (oxygen deficit): Produces toxic carbon monoxide (CO), black carbon soot (carbon black raw material)
2. Catalytic Steam Reforming (Core Petrochemical Reaction)
High temperature + nickel catalyst, industrial route for hydrogen & syngas:
\(CH_4 + H_2O(g) \xrightarrow{Ni,700\sim900℃} CO + 3H_2\)
Synthesis gas feedstock for ammonia, methanol, hydrogen fuel cells
3. Halogenation Free-Radical Substitution (UV light initiation)
Stepwise chlorination to produce four methane halide derivatives:
CH₃Cl (Methyl Chloride) → CH₂Cl₂ (Dichloromethane) → CHCl₃ (Chloroform) → CCl₄ (Carbon Tetrachloride)
Key fine chemical & solvent intermediates
4. Partial Oxidation & Pyrolysis
- Partial oxidation: Produces formaldehyde, methanol industrial feedstock
- High-temperature pyrolysis (1200 ℃+): Decomposes to acetylene, hydrogen, carbon black
5. Incompatibility & Dangerous Reactions
- Strong oxidants (liquid oxygen, chlorine, fluorine, hydrogen peroxide): Violent combustion, explosion risk under heating/compression
- Liquid halogens: Explosive mixture under UV irradiation
- No reaction with neutral inorganic salts, weak acids, weak bases at room temperature
Thermal Stability
- Stable at -50 ~ 300 ℃ without catalyst
- Decomposes above 600 ℃ without oxygen into carbon and hydrogen
- No polymerization risk, no self-reaction hazard under sealed storage
4. Four Industrial Grades – Full Quantitative Quality Specifications
Grade 1: Fuel-Grade Compressed Methane (CNG Mainstream Export, ≥98.0 vol%)
| Test Index | Standard Spec | Detection Method |
| CH₄ Main Volume Purity | ≥98.0 vol% | Gas Chromatography GC-TCD |
| C2-C5 Heavy Hydrocarbons (Ethane, Propane, Butane, Pentane) | ≤1.5 vol% | GC |
| Nitrogen (N₂) Inert Impurity | ≤0.4 vol% | GC |
| Carbon Dioxide (CO₂) | ≤0.1 vol% | GC |
| Total Sulfur (H₂S + Mercaptan) | ≤20 ppm | Microcoulomb sulfur analyzer |
| Water Dew Point | ≤-40 ℃ at operating pressure | Dew point hygrometer |
| Oxygen (O₂) | ≤100 ppm | GC |
| Appearance | Colorless odorless compressed gas, no liquid condensate at 20 ℃ | Visual inspection |
Application: Civil heating, vehicle CNG fuel, industrial boiler power generation
Grade 2: Chemical Synthesis Grade (99.5% High Purity, Petrochemical Feedstock)
| Test Index | Standard Spec | Detection Method |
| Methane ≥99.50 vol% | GC-TCD |
|
| C2+ heavy hydrocarbons ≤0.30 vol% | GC |
|
| N₂ ≤0.10 vol% | GC |
|
| CO₂ ≤10 ppm | GC |
|
| O₂ + Ar ≤10 ppm | GC |
|
| H₂O ≤30 ppm | Karl Fischer / Dew point |
|
| Total sulfur ≤0.5 ppm | Microcoulomb |
|
Application: Steam reforming to make hydrogen, ammonia, methanol synthesis feedstock
Grade 3: Ultra-High Purity Electronic Grade (5N, ≥99.999%) Semiconductor Specialty Gas
| Test Index | Standard Spec | Detection Method |
| CH₄ ≥99.999 vol% (5N) | High-sensitivity GC |
|
| C2+ hydrocarbons ≤0.1 ppm | GC-FID |
|
| O₂ + Ar ≤0.1 ppm | Trace oxygen analyzer |
|
| N₂ ≤0.2 ppm | GC |
|
| CO + CO₂ ≤0.1 ppm | GC |
|
| H₂O ≤0.3 ppm | Cryogenic dew point tester |
|
| Metal particle impurities ≥0.1μm ≤1 particle/L | Particle counter |
|
Application: Silicon wafer epitaxy, CVD coating, semiconductor doping, photovoltaic manufacturing
Grade 4: Research Calibration Standard Gas (6N, ≥99.9999%) Lab Instrument Reference
- Assay ≥99.9999 vol%, all trace impurities (O₂, N₂, CO, moisture, heavy hydrocarbons) <0.01 ppm
- Ultra-low metal ion contamination
Application: GC/MS calibration, combustion laboratory testing, environmental gas monitoring standard
5. Detailed Multi-Field Industrial Applications (Segmented High/Low Value Sectors)
5.1 Clean Energy Fuel Sector (Largest Consumption Volume)
- Civil Domestic Energy: Town pipeline natural gas for cooking, water heating, central heating, low-carbon alternative to coal/LPG
- Transportation Fuel: Compressed Natural Gas (CNG) taxis, buses, logistics trucks; Liquefied Natural Gas (LNG) heavy trucks, cargo ships, passenger vessels; lower NOx and particulate emissions than gasoline/diesel
- Power Generation: Combined-cycle gas turbine power plants, peak-shaving power stations, distributed on-site power for chemical factories
- Industrial Thermal Fuel: Glass kilns, ceramic furnaces, food baking ovens, metal forging furnaces; ultra-low sulfur avoids product discoloration
5.2 Petrochemical High-Value Feedstock (Core Export High-End Market)
- Syngas & Hydrogen Production: Steam reforming produces CO+H₂ synthesis gas for synthetic ammonia (fertilizer raw material), industrial hydrogen, fuel cell hydrogen
- Methanol Manufacturing: Partial oxidation syngas catalytic synthesis of methanol, basic solvent & plastic monomer
- Acetylene / Carbon Black Raw Material: High-temperature pyrolysis for acetylene (PVC monomer) and furnace carbon black (rubber reinforcing agent, ink pigment)
- Halogenated Methane Series: Chlorination to produce dichloromethane, chloroform, carbon tetrachloride for pharmaceutical solvent, refrigerant, cleaning agent
- Formaldehyde, Acetic Acid Intermediate: Controlled partial oxidation downstream fine chemical monomer
5.3 Semiconductor & Electronic Specialty Gas (High-Purity 5N/6N Grade Exclusive)
- CVD / MOCVD coating gas for silicon chip, LED, photovoltaic panel thin film deposition
- Carbon source dopant for silicon epitaxial layer manufacturing
- Wafer surface carbon film passivation auxiliary gas
- Plasma etching auxiliary gas for microchip precision processing
5.4 Laboratory, Calibration & Scientific Research
- GC, GC-MS, infrared spectrometer standard calibration reference gas for environmental monitoring, petrochemical detection
- Combustion dynamics laboratory test fuel for engine, boiler simulation experiments
- Cryogenic low-temperature experiment medium, low-temperature refrigeration carrier gas
- Catalyst performance evaluation reaction raw material for organic chemistry research
5.5 Special Industrial Scenarios
- Low-GWP refrigerant R50 for ultra-low temperature cryogenic equipment
- Fuel for small portable power generators, camping equipment
- Raw material for nitro-methane synthesis (explosive & pharmaceutical intermediate)
- Mine ventilation inert dilution gas to reduce underground explosion risk
6. Full Toxicology, Health Hazard & First-Aid Information
Toxicity Profile
- Acute Oral/Dermal Toxicity: Zero direct systemic toxicity; methane does not metabolize inside human body, no organ poisoning
- Primary Hazard: Simple inert asphyxiant (displaces oxygen in closed spaces)
- LC50 (Mouse inhalation, 2h): 50,000 ppm
- Occupational Exposure TWA Limit: 6700 mg/m³ (no chronic toxic effect limit, only oxygen displacement risk control)
Graded Asphyxiation Symptoms by Concentration
- 5–10 vol% methane in air: Mild headache, dizziness, slight shortness of breath
- 15–25 vol%: Severe fatigue, rapid heartbeat, impaired coordination, nausea
-
25 vol%: Loss of consciousness, respiratory arrest, fatal suffocation within minutes
Contact Hazards
- Inhalation: Asphyxiation risk as above
- Liquid Cryogenic Skin Contact: Instant severe frostbite, tissue necrosis risk
- Eye Contact with LNG Liquid: Corneal frostbite, temporary/permanent vision damage
- Skin Contact with Compressed Gas Jet: Rapid evaporative cooling frostbite
Complete First-Aid Procedures
- Inhalation: Immediately evacuate victim to fresh open air; if breathing stops, perform artificial respiration + oxygen supply; send to hospital
- Cryogenic Liquid Skin Frostbite: Do NOT rub frozen tissue; immerse affected area in lukewarm (37–40 ℃) water; remove contaminated frozen clothing gently; seek emergency medical treatment
- Eye Contact with LNG: Flush eyes continuously with room-temperature clean water for 15+ minutes, avoid hot water; ophthalmologist examination mandatory
- Fire Exposure Inhalation of Combustion Fumes: High-flow oxygen inhalation, monitor for CO poisoning symptoms
7. Storage, Handling & Compatibility Rules
Mandatory Storage Conditions
- Warehouse Classification: Class A flammable gas dedicated tank yard / explosion-proof gas warehouse
- Ambient Temperature Control: Strictly ≤30 ℃; maximum container surface temp cannot exceed 52 ℃ per EIGA standards
- Ventilation: Full natural + mechanical explosion-proof ventilation; continuous gas concentration monitoring alarm system
- Layout: Cylinders stored upright with anti-toppling brackets; separated by fire barrier walls; no underground confined storage
- Sealing: All cylinder valves fully closed when idle; pressure relief safety valves intact, no plugging
Strict Incompatible Materials (Separate Storage Mandatory)
- Strong oxidants: Liquid oxygen, chlorine gas, fluorine, hydrogen peroxide, potassium permanganate
- Halogen pure gases, liquid halogens
- Combustible liquid solvents stored in same compartment forbidden
- Food raw materials, edible chemicals, pharmaceutical raw materials cannot share warehouse
Safe Handling Precautions
- Only trained certified personnel operate gas cylinders; wear anti-static overalls, safety goggles, insulated cryogenic gloves for LNG operation
- All tools non-sparking copper alloy; no mobile phones, open flame, smoking within 15m radius
- All cylinder pipelines static grounded to eliminate static electricity buildup
- Do not drag, roll, drop or impact pressure cylinders; avoid valve collision damage
- After each use fully close cylinder valve; empty cylinders retain residual positive pressure to prevent air backflow
- Leak testing only with soap water; never use open flame to detect leakage
8. Packaging, Shipping & Full Transport Regulatory Details
Export Packaging Forms (3 Main Modes)
- Compressed Methane (UN1971): Seamless high-pressure carbon steel cylinders (40L, 80L, 120L standard specifications), working pressure 200 bar; equipped with safety relief valve, flame arrester, red hazard shoulder marking cap
- Cryogenic Liquid LNG Methane (UN1972): Insulated stainless steel vacuum tank containers (20ft / 40ft ISO tank) for full container ocean bulk shipment
- Small Lab Trial Packaging: 10L / 15L mini pressure cylinders with anti-leak valve assembly
Global Transport Compliance Rules
- UN Classification:
- UN1971: Compressed methane, Class 2.1 flammable gas, PG I
- UN1972: Refrigerated liquid methane, Class 2.1 cryogenic flammable gas, PG I
- Vehicle Requirements: Transport trucks fully explosion-proof electrical systems, exhaust pipe flame arrestor installed; equipped with CO₂ and dry powder fire extinguishers
- Loading Restrictions: Cylinders fixed upright with triangular wooden wedges; valve caps locked tight; cannot stack over two layers; absolutely no mixed loading with oxidants, toxic goods, food additives
- Ocean Shipment: IMDG Code compliant dangerous goods tank containers; full cargo declaration with MSDS, hazard identification certificate, pressure vessel inspection report
- Seasonal Transit Control: Summer transport only morning/evening delivery to avoid direct sunlight overheating; mid-way parking far from factory zones, open flames, residential areas
Full Export Documentation Package
- Certificate of Analysis (COA) batch purity report
- Material Safety Data Sheet (MSDS / SDS) compliant with GHS
- TDS technical data sheet
- Marine Dangerous Goods Declaration
- Pressure vessel periodic inspection certificate
- REACH / EIGA compliance statement
- Customs HS code classification certification
9. GHS Global Hazard Labeling & Safety Statements
Signal Word: Danger
Core Hazard Codes (H-Statements)
- H220: Extremely flammable gas
- H280: Contains gas under pressure; may explode if heated
- H336: May cause drowsiness or dizziness via oxygen displacement (asphyxiation)
Precautionary P-Statements
P210: Keep away from heat, sparks, open flames, hot surfaces – No smoking
P280: Wear safety eye protection, anti-static protective clothing
P377: Gas leak fire: Do not extinguish flame unless leak source can be safely closed
P381: Eliminate all ignition sources if safe to do so
P410 + P403: Protect from sunlight, store in well-ventilated location below 52 ℃
10. Fire Fighting & Spill Emergency Response
Approved Fire Extinguishing Agents
- Primary: Carbon Dioxide (CO₂) fire extinguisher, dry chemical powder
- Auxiliary: Water mist (only for cooling cylinder tank surface, cannot extinguish gas flame directly)
- Forbidden: Straight high-pressure water jet (no flame suppression effect, risk of cylinder thermal shock rupture)
Gas Leak Emergency Operation Steps
- Immediately cut all ignition sources, evacuate all personnel to upwind safe zone
- Isolate leakage area, restrict entry; activate explosion-proof ventilation to dilute gas concentration
- Stop gas supply by closing cylinder/tank master valve if operation is safe
- Use gas detector to monitor concentration until LEL drops below 1%
- Small indoor leak: Open all doors/windows full natural ventilation
- Large bulk tank leak: Spray continuous water mist to disperse rising methane gas cloud
11. Printable Export Standard COA Template
CERTIFICATE OF ANALYSIS
Product Name: Methane Gas (CH₄)
CAS No.: 74-82-8
Grade: Export Industrial Chemical Synthesis Grade (99.5%)
Batch No.: ____________
Packaging: 40L High-Pressure Steel Cylinder / 20ft LNG ISO Tank
Production Date: ____________
| Test Item | Standard Specification | Test Result | Test Method |
| Methane Volume Purity | ≥99.50 vol% |
| GC-TCD Gas Chromatography |
| C2+ Heavy Hydrocarbons (Ethane+) | ≤0.30 vol% |
| GC-FID |
| Nitrogen Impurity (N₂) | ≤0.10 vol% |
| GC-TCD |
| Carbon Dioxide (CO₂) | ≤10 ppm |
| GC-TCD |
| Oxygen + Argon (O₂+Ar) | ≤10 ppm |
| Trace Oxygen Analyzer |
| Water Content (Moisture) | ≤30 ppm |
| Dew Point Cryogenic Test |
| Total Sulfur Content | ≤0.5 ppm |
| Microcoulomb Sulfur Detector |
| Appearance | Colorless, odorless compressed gas, no liquid condensate | Visual Inspection |
|
Conclusion: This batch fully complies with export premium chemical synthesis grade standard of Methane (CAS 74-82-8).
Inspector Signature: ____________
Date of Issuance: ____________
TDS
Republic of the Congo
Thailand
