a process for liquefying natural gas in conjunction with producing a liquid stream containing predominantly hydrocarbons heavier than methane is disclosed . in the process , the natural gas stream to be liquefied is partially cooled , expanded to an intermediate pressure , and supplied to a distillation column . the bottom product from this distillation column preferentially contains the majority of any hydrocarbons heavier than methane that would otherwise reduce the purity of the liquefied natural gas . the residual gas stream from the distillation column is compressed to a higher intermediate pressure , cooled under pressure to condense it , and then expanded to low pressure to form the liquefied natural gas stream .