The accelerating effect of NH4Cl on gas phase reaction of oxidative coupling of methane at elevated pressures

The effect of different Cl-containing additives on the gas phase reaction of oxidative coupling of methane (OCM) at elevated pressures has been investigated. NH4Cl was found to have the best beneficial effect to improve C2 selectivity; however, CH3Cl and C2H4Cl2 have almost no effect on gas phase reaction of OCM at elevated pressures. We conclude that Cl− and NH3 in NH4Cl or HCl played the key roles in improving the selectivity to C2. Although the addition of only NH3 improved the C2 selectivity very little, NH3 favored the formation of Cl radical in the presence of HCl. The results also imply that Cl atoms in organic compounds have a different effect from Cl− ion in inorganic compounds on gas phase reactions of OCM.