Process for the production of neopentyl glycol NPG
Publication Date: 2015-Nov-16
The IP.com Prior Art Database
Neopentyl glycol NPG CAS No 126 30 7 is produced by aldolization of iso butyraldehyde iBA with formaldehyde FA in the presence of trimethylamine TMA as catalyst to hydroxy pivaldehyde HPA CAS No 597 31 9 which is then hydrogenated in the presence of a copper catalyst to neopentyl glycol The publication describes the performance of the two process steps as well as the subsequent isolation purification and conditioning of the neopentyl glycol to flakes and an aqueous solution Furthermore it also comprises the plant safety concept a Process Flow Diagram and a Heat and Mass Balance
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Process Description including Plant Safety Concept
1. Process Description
NPG - neopentylglycol
iBA - iso-butyraldehyde
FA - formaldehyde
TMA - trimethylamine
HPA - hydroxypivalinaldehyde H2 - hydrogen
The process consists of four parts:
• Synthesis of HPA
• Hydrogenation of HPA to NPG
• Distillation: Separation of NPG from water and by-products
• Conditioning to liquid or solid sales products
Process Flow Diagram: See separate diagram
The synthesis of HPA is performed by aldolization reaction of aqueous FA and iBA in the presence of catalytic amounts of TMA.
catalyst: trimethylamin (TMA)
T = 70°C, recirculation of iBA and TMA
∆HR ~ -59 kJ/mol
HPA in H2O: melting point below 55°C; depends on water content
The exothermic reaction takes place in two cascading Synthesis Reactors (R10, R11) at temperatures of 70 to 75°C and a pressure of approx. 3.5 bara. The heat of reaction is
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removed by circulation of the reaction mixtures by Synthesis Pump P10 and P11 through the external Synthesis Coolers E10 and E11.
The raw materials FA, iBA and TMA are mixed in the pipeline before entering the first Synthesis Reactor R10 via a nozzle at the bottom. In the second Synthesis Reactor R11 the conversion of FA and iBA is further continued.
Unused iBA and TMA are recovered downstream in iBA Recovery Tower C10 and are recycled to the first Synthesis Reactor R10. Thus, the overall conversion of iBA reaches approx.. 98 %, whereas the conversion of FA, which is used in a slight excess, reaches approximately 92 %.
In the iBA Recovery Tower C10, iBA and TMA are distilled overhead together with water and some by-products. Condensation proceeds in two steps: the first iBA Recovery Condenser, E13, generates the reflux to the iBA Recovery Tower C10, the second iBA Recovery Condenser, E14, condenses the recycle stream to the first Synthesis Reactor R10 via iBA Collection Vessel V14 and iBA Recycle Pump P14. Non-condensable vapor in iBA Recovery Condenser E14 is fed to a thermal oxidizer for incineration.
The iBA Recovery Tower C10 is also equipped with a falling film evaporator iBA Recovery Reboiler E12. From the sump of the iBA Recovery Tower C10 the HPA Pump P12 transfers the crude HPA via the HPA Cooler E15, in which the crude HPA is cooled down to approx. 70°C, to the Hydrogenation Feed Vessel V15. Prior to entering V15 the crude HPA is pH-adjusted by TMA addition.
The hydrogenation of HPA to NPG is performed using a copper catalyst at a pressure of approx. 38 bara and temperatures in the range of 100 to 135°C.
with copper catalyst
p ~ 38 bara; T = 100-135°C
main reactor and secondary reactor; main reactor with circuit ∆HR ~ -104 kJ/mol (at 25°C)
melting point depends on residual content of HPA in NPG