Method for preparation of methylene diphenyl diisocyanate (MDI)
A technology of diisocyanate and diphenylmethane, which is applied in the field of preparing diphenylmethane diisocyanate, can solve the problems of high reaction temperature, large amount of solvent, and further improvement of product yield, and achieve the effect of increasing yield and high yield
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Embodiment 1
[0016] The zinc acetate solution with the zinc ion molar concentration of 0.25 / L is mixed with an appropriate amount of activated carbon (the specific surface area of activated carbon is 800m 2 / g, the pore volume is 0.6cm 3 / g, the average pore size is 15nm) equal volume mixing and impregnation, the impregnation time is 8h, after impregnation, dry at 120°C for 3h, repeat the above process once, then bake in 400°C air atmosphere for 3h, to obtain the zinc oxide catalyst. Weigh 50g of MDC and put it into a 1000mL four-necked bottle, add 500g of dimethyl phthalate, add the above-mentioned zinc oxide catalyst, the addition amount is 5% of the solvent mass, put the reaction bottle with the material into the oil bath, and Install a stirrer, a thermometer, a separation column and a nitrogen air duct, raise the temperature of the reaction solution to 200° C. under nitrogen protection and stirring, and continue the reaction for 40 minutes. After the reaction is finished, the reacti...
Embodiment 2
[0018] The zinc acetate solution with the molar concentration of zinc ions of 0.1 / L is mixed with an appropriate amount of activated carbon (the specific surface area of activated carbon is 1000m 2 / g, the pore volume is 0.3cm 3 / g, with an average pore size of 10nm) equal volumes mixed and impregnated, impregnated for 10h, dried at 100°C for 5h after impregnated, repeated the above process once, and then baked at 300°C for 5h in an air atmosphere to obtain a zinc oxide catalyst. Weigh 50g of MDC into a 1000mL four-neck bottle, add 250g of dimethyl carbonate, add the above-mentioned zinc oxide catalyst, the addition amount is 10% of the solvent mass, put the reaction bottle with the material into the oil bath, and install the stirrer , a thermometer, a separation column and a nitrogen air duct, the temperature of the reaction solution was raised to 220°C under nitrogen protection and stirring, and the reaction lasted for 30 minutes. After the reaction was completed, the con...
Embodiment 3
[0020] The zinc acetate solution with the molar concentration of zinc ions of 0.5 / L is mixed with an appropriate amount of activated carbon (the specific surface area of activated carbon is 700m 2 / g, the pore volume is 1.0cm 3 / g, the average pore size is 25nm) equal volume mixing impregnation, the impregnation time is 9h, after impregnation, dry at 110°C for 4h, repeat the above process once, then bake in the air atmosphere of 500°C for 2h, to obtain the zinc oxide catalyst. Weigh 50g of MDC and put it into a 1000mL four-necked bottle, add 750g of dimethyl phthalate, add the above-mentioned zinc oxide catalyst, the addition amount is 0.02% of the solvent mass, put the reaction bottle with the material into the oil bath, and Install a stirrer, a thermometer, a separation column and a nitrogen air duct, raise the temperature of the reaction solution to 180° C. under nitrogen protection and stirring, and continue the reaction for 60 minutes. After the reaction was completed,...
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Abstract
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