a modified purifier process , includes supplying a first stream of a feed gas containing hydrogen and nitrogen in a mol ratio of about 2 : 1 , and also containing methane and argon , then cryogenically separating the feed gas into the following : f ) a second stream of synthesis gas containing hydrogen and nitrogen in a mol ratio of about 3 : 1 , g ) waste gas containing principally nitrogen , and also containing some hydrogen and all of the methane supplied in the first stream , and splitting the waste gas into : h ) a third stream of hydrogen / nitrogen gas i ) a fourth stream of high concentrated nitrogen j ) a fifth stream of methane rich gas , to be used as fuel . the combined second and third streams typically are passed to an ammonia synthesis process .