INTEGRATED METHOD FOR THE PREPARATION OF TRIOXANE FROM FORMALDEHYDE

摘要

Integrated method for the preparation of trioxane from formaldehyde, comprising the steps: a) introduction of a feeding flow A1 containing formaldehyde and water and a return flow B3 consisting essentially of formaldehyde and trioxane into a formaldehyde concentration unit, wherein said flows are separated into a formaldehyde-rich flow A2 and a flow A3 consisting essentially of water; b) introduction of a product flow C1, containing trioxane, water, and formaldehyde, a return flow E1 containing trioxane, water, and formaldehyde, and possibly flow A2 into a first low-pressure distillation column, wherein said flows are distilled at a pressure of from 0.1 to 1.5 atmospheres, with a trioxane-enriched flow B1 containing predominantly trioxane, and also water and formaldehyde, a slough removal flow B2 consisting essentially of formaldehyde and water, and the return flow B3 containing predominantly water, and also formaldehyde and trioxane removed as a side removal flow; c) introduction of a slough removal flow B2 and possibly the flow A2 into a trioxane synthesis reactor, wherein said flows are allowed to react, and wherein the flow C1 containing trioxane, water, and formaldehyde is obtained; d) introduction of a flow B1 into a mid-pressure distillation column, wherein said flow is distilled at a pressure of from 1.0 to 3.0 atmospheres, wherein a low boiler stream D1 containing methanol, methylal, and methylformate,and a stream D2 containing predominantly trioxane and also formaldehyde and water are obtained; e) introduction of a stream D2 into a high-pressure distillation column, wherein said stream is distilled at a pressure of from 2.5 to 10.0 atmospheres, wherein the return flow E1 contains trioxane, water, and formaldehyde, and a product flow E2 consisting essentially of trioxane is obtained; wherein flow A2 can be introduced into either the low-pressure distillation column or into the trioxane-35 synthesis reactor, or into both.