Process and device for preparing trioxane from methanol

A process for preparing trioxane from methanol, comprising:

• step 1:
• subjecting a mixture of methanol and methylal to a reaction under an action of an oxidation catalyst to obtain formaldehyde, and absorbing the formaldehyde with water to obtain a concentrated formaldehyde aqueous solution;
• step 2:
• in a trioxane synthesis reactor, subjecting the concentrated formaldehyde aqueous solution to a cyclization under an action of a cyclization catalyst to obtain a mixture containing trioxane, and passing the mixture containing trioxane through a trioxane concentration tower to obtain a crude trioxane product;
• step 3:
• converting a by-product and unreacted formaldehyde in the crude trioxane product into methanol through a catalytic refinement, conducting a dehydration through a membrane dehydration process, and subjecting a retentate to a dealcoholization to obtain purified trioxane;
• and
• step 4:
• after the purified trioxane is separated, combining remaining streams of an entire process to obtain a mixture comprising methanol, water, and a predetermined amount of trioxane, and subjecting the mixture comprising methanol, water, and a predetermined amount of trioxane to a reactive distillation to obtain a mixture of methanol and methylal at a top of a reactive distillation tower and water at a bottom of the reactive distillation tower;
• returning the mixture of methanol and methylal to step 1;
• and returning the water to a formaldehyde absorption tower, or discharging the water from a system.