CN1053664C

CN1053664C - Process for producing methaldehyde

Info

Publication number: CN1053664C
Application number: CN96117046A
Authority: CN
Inventors: 陈志建; 吴刚; 朱盘棣; 胡晓; 沈新安; 李敬孝; 刘徐生
Original assignee: XUZHOU SOLVENT PLANT
Current assignee: XUZHOU SOLVENT PLANT
Priority date: 1996-07-30
Filing date: 1996-07-30
Publication date: 2000-06-21
Anticipated expiration: 2016-07-30
Also published as: CN1150590A

Abstract

The present invention discloses a production technology of methaldehyde. Acetaldehyde is thrown into a polymerization reaction kettle after cooled, and simultaneously, ether is thrown, and then, the acetaldehyde and the ether are mixed and cooled without stop; an acidic catalyst is mixed for three hours after added into the polymerization reaction kettle; then, the filtration is carried out, and solids are washed and then dried. Thereby, white crystalline methaldehyde can be obtained; filter liquor is sent to a still kettle to be heated; then sulfuric acid is added to be taken as a catalyst to distill and separate the acetaldehyde and the ether; the acetaldehyde and the ether are used in next batch charging. The technology is simple and is easy to implement. The reaction temperature is from-15 DEG C to-5 DEG C and is easy to control. The reaction is stable. Moreover, the methaldehyde yield can reach 6% to 10%, and thereby, the purpose of higher yield is reached.

Description

Process for producing methaldehyde

The present invention relates to a kind of process for producing methaldehyde, a kind of specifically production technique with the acetaldehyde production methaldehyde.

Use the acetaldehyde production methaldehyde in the English Patent 1055210, temperature of reaction in this production technique is-40 ℃～-10 ℃, the add-on of catalyzer is 0.05～0.7% (w/w), methaldehyde yield is 0.5%～5% (w/w), temperature of reaction requires lotus to carve in the described production technique of this patent, wayward in the production process, methaldehyde yield is low.

Use the acetaldehyde production methaldehyde in the Deutsches Wirtschafts Patent 236315, its production technique is: 150 liters of acetaldehyde are cooled to-14 ℃, add 0.05 liter of hydrochloric acid of catalyzer, 5 hours reaction times, the polymerization degree 90%, methaldehyde yield is 4.5%～7.2%, and the methaldehyde yield of the described production technique of this patent is lower.

The objective of the invention is to provide a kind of polyreaction under comparatively high temps, to carry out and be easy to controlling the process for producing methaldehyde that methaldehyde yield is higher.

Realize purpose first scheme of the present invention: in 1000 liters reactor, drop into 0 ℃ of acetaldehyde 560kg, add about 40kg ether again, be cooled to-15 ℃, with an acidic catalyst for preparing promptly: the about 4kg of hydrochloric acid, the about 1kg of ether, the about 1kg of pyridine, bromination is received about 0.5kg, the about 0.3kg of oxammonium hydrochloride, under constantly stirring and cooling off, be added in the polymeric kettle, observe the polymeric kettle temperature, the control an acidic catalyst adds speed, make the polymeric reaction temperature in the polymeric kettle be no more than 0 ℃, after an acidic catalyst adding is finished, it is about 3 hours at-10 ℃～-5 ℃ that the polymerization temperature in the kettle is kept in continuous stirring and cooling, can in polymeric kettle, emit, filter, to solids through the washing, get final product after the drying the white crystalline methaldehyde.

Realize the alternative plan of the object of the invention: in 1000 liters reactor, drop into 0 ℃ of acetaldehyde 560kg, add about 40kg ether again and be cooled to-15 ℃, with an acidic catalyst for preparing promptly: the about 2.8kg of Hydrogen bromide, the about 1.1kg of pyridine, under constantly stirring and cooling off, be added in the polymeric kettle, observe the polymeric kettle temperature, the control an acidic catalyst adds speed, make the polymeric reaction temperature in the polymeric kettle be no more than 0 ℃, an acidic catalyst add finish after, constantly stir and cooling keep the polymerization temperature in the kettle-10 ℃～-5 ℃ about 3 hours, can in polymeric kettle, emit, filter, to solids through the washing, get final product after the drying the white crystalline methaldehyde.

In the such scheme,, make the methaldehyde that higher yield be arranged in this technology because the adding of an acidic catalyst helps generating the methaldehyde; Its yield is 6%～10%, owing to begin to add a certain amount of ether in reaction, can effectively stop the sedimentation of paraldehyde, thereby can be by filtering to isolate the crystalline methaldehyde; Because being controlled at-10 ℃～-5 ℃, temperature of reaction make batch process be easy to control.This production technique is simply easy to implement, and temperature of reaction is easy to control reacting balance, and methaldehyde yield can cross 6%～10%, has reached the higher purpose of yield.

Embodiment 1: in 1000 liters reactor, drop into 0 ℃ of acetaldehyde 560kg, add about 40kg ether again and be cooled to-15 ℃, with an acidic catalyst for preparing promptly: the about 4kg of hydrochloric acid, the about 1kg of ether, the about 1kg of pyridine, bromination is received about 0.5kg, the about 0.3kg of oxammonium hydrochloride, under constantly stirring and cooling off, be added in the polymeric kettle, observe polymeric kettle temperature control an acidic catalyst and add speed, make the polymeric reaction temperature in the polymeric kettle be no more than 0 ℃, after an acidic catalyst adding is finished, it is about 3 hours at-10 ℃～-5 ℃ that the polymerization temperature in the kettle is kept in continuous stirring and cooling, can emit in the polymeric kettle and filter, to solids through washing, get final product after the drying the white crystalline methaldehyde.Filtrate is delivered in the still kettle and is heated, and add sulfuric acid and make catalyzer, the paraldehyde depolymerization in the filtrate, control depolymerization tower top temperature is at 20 ℃～21 ℃, and acetaldehyde and ether fractionation by distillation are come out, and prepare the use that feeds intake next time.

Embodiment 2, and an acidic catalyst that uses in the process for producing methaldehyde is the about 2.8kg of Hydrogen bromide, the about 1.1kg of pyridine, and other technological process and embodiment 1 omit together.

Claims

1, a kind of process for producing methaldehyde, it is characterized in that: in 1000 liters reactor, drop into 0 ℃ of acetaldehyde 560kg, add the 40kg ether again, be cooled to-15 ℃, with an acidic catalyst for preparing promptly: hydrochloric acid 4kg, ether 1kg, pyridine 1kg, bromination is received 0.5kg, oxammonium hydrochloride 0.3kg, under constantly stirring and cooling off, be added in the polymeric kettle, observe the polymeric kettle temperature, the control an acidic catalyst adds speed, make the polymeric reaction temperature in the polymeric kettle be no more than 0 ℃, an acidic catalyst add finish after, constantly stir and cooling keep the polymerization temperature in the kettle-10 ℃～-5 ℃ about 3 hours, can in polymeric kettle, emit, filter, to solids through the washing, get final product after the drying the white crystalline methaldehyde.

2, a kind of process for producing methaldehyde, it is characterized in that: in 1000 liters reactor, drop into 0 ℃ of acetaldehyde 560kg, add the 40kg ether again, be cooled to-15 ℃, with an acidic catalyst for preparing promptly: Hydrogen bromide 2.8kg, pyridine 1.1kg, under constantly stirring and cooling off, be added in the polymeric kettle, observe the polymeric kettle temperature, the control an acidic catalyst adds speed, makes the polymeric reaction temperature in the polymeric kettle be no more than 0 ℃, after an acidic catalyst adding is finished, constantly stir and cooling keep the polymerization temperature in the kettle-10 ℃～-5 ℃ about 3 hours, can in polymeric kettle, emit; Filter, to solids through washing, get final product after the drying the white crystalline methaldehyde.