Abstract: Process for the separation of an aqueous mixture of trioxane and formaldehyde and corresponding applications. The aqueous trioxane and formaldehyde mixture has first trioxane:formaldehyde ratio. The process includes the steps of reacting the aqueous mixture of trioxane and formaldehyde with urea, and separation an exiting vapor phase having a second trioxane:formaldehyde ratio that it higher than the first trioxane:formaldehyde ratio. An aqueous mixture of trioxane and formaldehyde coming from a reactor in which trioxane is being synthesized or from a distillation column in which a prior aqueous mixture of trioxane and formaldehyde can be separated from the excess formaldehyde. Raw material for the production of urea-formaldehyde glues or resins can be formed.

Abstract: A process for the separation of an aqueous mixture of trioxane and formaldehyde and corresponding applications are disclosed. The aqueous trioxane and formaldehyde mixture has a first trioxane:formaldehyde ratio, and the process comprises a step of reacting the aqueous mixture of trioxane and formaldehyde with urea and a step of separating an exiting vapour phase having a second trioxane:formaldehyde ratio that is higher than the first trioxane:formaldehyde ratio. Possible applications of the process are for the separation of an aqueous mixture of trioxane and formaldehyde coming from a reactor in which trioxane is being synthesized or from a distillation column in which a prior aqueous mixture of trioxane and formaldehyde is separated from the excess formaldehyde. Another possible application is for preparing raw material for the production of urea-formaldehyde glues or resins.

Abstract: The process uses a supply column and additional heat exchangers associated with absorption columns. Air and methanol from outside and a subcurrent of methanol, originating from a cold methanol current exiting from the supply column, are fed to the supply column. This exiting current recirculates through the additional heat exchangers and is divided into the subcurrent which returns to the supply column and another subcurrent which is fed to an evaporator. A methanol-air mixture exits from the head of the supply column and is fed to an evaporator. The cold methanol is cooled in the supply column by evaporation of the methanol forming part of the methanol-air mixture.

Abstract: A process for the preparation of pentaerythritol, comprising reacting formaldehyde, acetaldehyde and sodium hydroxide and acidification with formic acid. These steps take place in a reactor with supplies of formaldehyde, sodium hydroxide, acetaldehyde and formic acid and at the end the solution formed is evacuated to a buffer tank of larger capacity than the reactor. In the reactor new reactions and acidifications are successively reinitiated by new supplies. In the first place a formaldehyde solution is added, followed by simultaneous but separate additions of sodium hydroxide solution and acetaldehyde, forming a reaction mixture in such a way that the flowrates of the solutions vary with the time and that the temperature at which the reactions are conducted also varies with the time. The outflow from the buffer tank is constant and continuous.