4A vs 3A molecular sieves

Which molecular sieve is best for drying butane? 4A or 3A? Why?

I think 4A is what you want. But I'm not 100% sure yet. I do plan on getting both myself.

3A
Commercial dehydration of unsaturated hydrocarbon streams, including cracked gas, propylene, butadiene,
acetylene; drying polar liquids such as methanol and ethanol. Adsorption of molecules such as NH3 and H2O
from a N2/H2 flow. Considered a general-purpose drying agent in polar and nonpolar media.

4A
Preferred for static dehydration in closed liquid or gas systems, e.g., in packaging of drugs, electric components
and perishable chemicals; water scavenging in printing and plastics systems and drying saturated hydrocarbon
streams. Adsorbed species include SO2, CO2, H2S, C2H4, C2H6, and C3H6. Generally considered a universal drying
agent in polar and nonpolar media.

This link may interest some people.

Design and Operation of molecular sieve units