| abstract |
FIELD: chemistry. n SUBSTANCE: invention relates to method of processing by-products of liquid-phase synthesis of isoprene from isobutylene and formaldehyde or formaldehyde-containing products, in particularly 4,4-dimethyl-1,3-dioxane in temperature interval 400-480°C in presence of water steam on alumosilicate-containing catalyst with preliminary heating of by-products to temperature 400-550°C in presence of water steam, characterised by carrying out of process at initial temperature 5-40°C lower and final temperature 5-40°C higher than average temperature of contacting with gradual temperature increase from initial to final and with permanent lowering of volume rate of raw material supply in the beginning of cycle of contacting 3-15% higher, and in the end of cycle 3-15% lower than average cycle volume rate of raw material supply. n EFFECT: increase of total output of useful products in processing of pyran fraction, fraction of by-products, or their mixture. n 3 cl, 4 tbl, 7 ex |