Synthesis of hydrothermally stable MCM-41 with initial adjustment of pH and direct addition of NaF

The synthesis of a hydrothermally stable MCM-41 was conducted at 100 degree s C for 24 h ill a 15 mi Teflon-lined Morey type autoclaves. Results show t hat a hydrothermally stable MCM-41 with long range ordering of its hexagona l array can easily be prepared. With addition of an optimum amount of NaF a nd with appropriate pH adjustment, an assynthesized MCM-41 shows excellent hydrothermal stability up to 433 K. XRD, magic angle spinning Si-29 NMR, N- 2-adsorption and TEM data show well-ordered structure. It was found that th e addition of NaF and the order of mixing are critical in the formation of this hydrothermally stable MCM-41. (C) 2000 Elsevier Science B.V. All right s reserved.