This also means 4A sieves are unsuitable for drying these solvents 3A sieves are required. 4A sieves will also release substantial heat if an added dry solvent is too small and can compete with water for their pores: even very dry methanol, ethanol, acetone and acetonitrile will heat substantially on contact with 4A sieves. Heating to 250C or above for 12h does a good job regenerating zeolite sieves in my experience, there are even microwave methods for people in a hurry! Active sieves, both 4A and 3A, release a large amount of heat when added to water and this is a good test add several drops of water to 3-4 sieves in a GLOVED hand and it will boil if they are highly active.
0 kommentar(er)
