Sulfur- and nitrogen-containing phenol-formaldehyde co-resites for probing the thermal behaviour of heteroatomic forms in solid fuels


Ismail K., Sirkecioglu O. , ANDRESEN J., BROWN S., HALL P., SNAPE C.

POLYMER, cilt.37, ss.4041-4048, 1996 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 37 Konu: 18
  • Basım Tarihi: 1996
  • Doi Numarası: 10.1016/0032-3861(96)00243-1
  • Dergi Adı: POLYMER
  • Sayfa Sayıları: ss.4041-4048

Özet

In order to probe the formation of sulfur- and nitrogen-containing gases during the pyrolysis and combustion of coals and other solid fuels, non-softening model substrates are required. In this respect, phenol-formaldehyde (PF) resins are ideal since they readily facilitate the incorporation of individual heteroatomic functions into a highly crosslinked matrix. A series of sulfur- and nitrogen-containing co-resites have been prepared using phenol with, as the second component, thiophene, dibenzothiophene, diphenylsulfide, benzyl phenyl sulfide, thioanisole, 8-hydroxyquinoline and 2-hydroxycarbazole. A mole ratio of 3 : 1 (phenol: heteroatom-containing component) was adopted in order to ensure that a reasonably high degree of crosslinking was achieved. Resoles containing diphenyldisulfide were also prepared but, due to the comparable bond strengths of the S-S and C-O linkages, a curing temperature of only 130 degrees C was used to avoid cleavage of the disulfide bond. The virtually complete elimination of ether and methylol functions from the resoles by curing at 200 degrees C was monitored by solid-state C-13 nuclear magnetic resonance (n.m.r.) spectroscopy. The resultant resites were also characterized by sulfur K-edge X-ray absorption near-edge structure (XANES.) spectroscopy, X-ray photoelectron spectroscopy (X.p.s.) and differential scanning calorimetry (d.s.c.). Simple air oxidation was found to selectively convert the aliphatic-bound sulfur to a mixture of sulfones and sulfoxides. Applications of the resites in fuel science are described. Copyright (C) 1996 Elsevier Science Ltd.