regenerating nitrogen dioxide, in {HEAD ~ a second zone} of {TAIL ~ said voloxidation vessel}, by reacting oxidizing gas comprising nitrogen monoxide and oxygen at a temperature ranging from 0 80° C., wherein said first zone and said second zone are separate 
of
regenerating nitrogen dioxide , in { HEAD ~ a second zone } of { TAIL ~ said voloxidation vessel } , by reacting oxidizing gas comprising nitrogen monoxide and oxygen at a temperature ranging from 0 80 ° C. , wherein said first zone and said second zone are separate
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH