Patent ID: 7064177

Claim:
A process for preparing polyoxymethylene by contacting a formaldehyde source with a catalyst of the formula I [Cp v ML w ] m+ Z m/n n− (I) where M is Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh or Ir, Cp is a cyclopentadienyl ligand C 5 H (5-u) R 1 u , where u is from 0 to 5 and R 1 is alkyl, alkenyl, aryl, heteroaryl, aralkyl, COOR 2 , COR 2 , CN or NO 2 , and R 2 is H, alkyl, aryl or aralkyl, v is 1 or 2, each L is independently a nitrile, CO or a ligand displaceable by CO, w is an integer from 0 to 4, Z is an anion, and m and n are each independently an integer from 1 to 3.