Removal of ethylene from silane using a distillation step after separation using a zeolite molecular sieve

A process for removing impurities from a stream of silane comprising:

• a) passing a stream of silane, said stream of silane containing heavier impurities, lighter impurities and ethylene, through a first distillation column at a first temperature and pressure sufficient to remove said lighter impurities, leaving a second stream;
• b) passing said second stream through a second distillation column at a second temperature and pressure sufficient to remove said heavier impurities, leaving a third stream;
• c) passing said third stream through a molecular sieve, said molecular sieve having a porosity of about 4 angstroms, at a third temperature and pressure sufficient to absorb the majority of the ethylene in said third stream onto said molecular sieve and convert the remainder of the ethylene in said third stream to ethylsilane, leaving a fourth stream containing ethylsilane;
• and
• d) passing said fourth stream containing ethylsilane through a third distillation column at a fourth temperature and pressure sufficient to produce a fifth stream containing a reduced concentration of ethylsilane.