Product

MAPD stands for Methylacetylene-Propadiene. It refers to a mixture of two C₃ unsaturated hydrocarbons: methylacetylene (also called propyne, CH₃C≡CH) and propadiene (also called allene, H₂C=C=CH₂). These compounds are structural isomers (same molecular formula, C₃H₄) and often coexist in equilibrium, especially in industrial contexts.

MAPD is typically encountered as a byproduct mixture in the production of propylene during steam cracking of hydrocarbons. Its presence in propylene streams can be problematic, as both methylacetylene and propadiene can poison polymerization catalysts used to make polypropylene and other polymers. Therefore, removal or hydrogenation of MAPD is a critical step in petrochemical processes to purify propylene for downstream use.

• Methylacetylene: CH₃C≡CHCH₃C≡CH

• Propadiene: H₂C=C=CH₂H₂C=C=CH₂

MAPD physical properties closely align with those of its individual components and are typically reported as follows:

• Molecular Weight: 40.1
• Boiling Point (Bp): Range from -36°C to -4°C (depending on the isomer ratio and conditions; pure components boil at about -23°C [propyne] and -34°C [propadiene])
• Melting/Freezing Point (Tm): -213°F (approximately -136°C), which matches the melting point of propadiene
• Density: Specific gravity is about 0.576 at 59°F (15°C) (relative to water), and vapor density is 1.48 (relative to air = 1)