to remove moisture that had been absorbed the thus calcined product was again disposed in the air to absorb environmental moisture the resulting alumina showed a weight increase of 10 4 as compared to its weight measured at the time of the second calcination after being exposed to the air 11 grams of the alumina was taken into a quartz reaction tube and dried at 500 u00b0 c for 1 5 hours with nitrogen fed at a rate of 250 ml min halogenation was effected by passing 2 5 ml min of ccl 2 f 2 gas and 250 m min of nitrogen containing 20 ppm of moisture through the tube over 20 minutes the halogenated product contained 0 70 by weight of fluorine and 1 18 of chlorine for purposes of illustration this product is herein referred to as catalyst a 1 isomerization of 1 butene was carried out with use of catalyst a 1 in which a starting material was 1 butene of 98 1 mole purity containing 1 5 mole of n butane diluted two times with nitrogen and the starting material was reacted at 400 u00b0 c at atmospheric and at 1 000 ghsv the composition of the gas at the outlet of the tube was analyzed upon a lapse of 5 hours to show 4 3 wt of lt c 4 60 2 wt of n butene 30 9 wt of i butene 0 8 wt of n butene and 3 8 wt of gt c 4 the outlet gas was further analyzed 50 hours after initiation of the reaction whereupon its composition contained 2 0 wt of lt c 4 68 5 wt of n butene 27 5 wt of i butene 0 9 wt of n butane and 1 1 wt of gt.