FIELD: chemistry.
SUBSTANCE: invention relates to a method of processing methyldihydropyran and/or by-products of synthesis of isoprene from isobutylene and formaldehyde via thermocatalytic decomposition thereof over an aluminosilicate-containing catalyst with preheating (or without) of the starting material in the presence of water vapour followed by condensation of the obtained contact gas to form aqueous and oil layers. Reaction products - isoprene, isobutylene and formaldehyde - are then extracted from said layers. The method is characterised by that an isoprene fraction containing 3-25 wt % isobutylene dimers is added to the contact gas at temperature 35-90°C, with weight ratio of the isoprene fraction to the contact gas equal to (0.02-0.15):1.
EFFECT: use of the present method enables to considerably improve the quality of waste water from the process and reduce loss of the end products without reducing selectivity of the process and without increasing deposition of coke on the catalyst.
1 cl, 4 ex, 1 tbl
