and in which the material containing hard-to-convert oxygenates includes compounds selected from a group comprising formaldehyde, acetaldehyde, hydroxyaldehyde, glyoxal, acetone, acetic acid, MeOAc, EtOAc, furfurol, furfuryl alcohol, phenol, anisole, pyrocatechol, guaiacol, cresol, cresolol, eugenol,...