THE CATALYST FOR OXIDATIVE COUPLING OF METHANE PREPARED FROM ZIRCONYLCHLORIDE AND SODIUM PYROPHOSPHATE

The catalysts prepared from zirconyl chloride and sodium pyrophosphate exhibited high activity and selectivity for the oxidative coupling of methane. We suggest that the catalytically active substances are most likely to be NaCl-promoted sodium zirconium phosphates and NaCl plays a key role in activity and selectivity of the catalyst system. The hi ghest C2+ selectivity was 79% at the methane conversion of 28% (C2+ yi eld 22%) and the highest C2+ yield was about 30% with the C2+ selectiv ity of 66-70% at the methane conversion of 41-44%. The ethene/ethane r atio higher than 10 and the C3+ selectivity of about 10-20% were obtai ned. Over the catalysts with the Na/Zr ratio greater than about 2, the C2+ selectivity did not decrease much with time on-stream in spite of the significant decrease of the activity. The main reason for the cat alyst deactivation is probably the disappearance of NaCl. (C) 1997 Els evier Science B.V.