A method and device for producing tetramethylpiperidinol by continuous catalytic hydrogenation

Abstract

The invention belongs to the technical field of hindered amine light stabilizers, and discloses a method and a device for producing 2, 2, 6, 6-Tetramethyl-4-piperidinol through continuous catalytic hydrogenation. According to the technical scheme, the method includes steps as follows: tetramethyl piperidone and ethyl alcohol are mixed, so that a feed liquid is formed; then the feed liquid is placed in reaction kettles and taken as bottom materials, and a pumping mechanism is started and injects the feed liquid into a primary reaction kettle with a constant flow; the reaction temperatures of the reaction kettles are kept, a reaction fluid overflows from a previous reaction kettle to the next reaction kettle for reaction and then overflows to a rotary sedimentation separator; and the well reacted feed liquid is separated from a system through the separator. According the method and the device, relatively regular technological conditions can be realized, and the reaction can be always and continuously performed under conditions of high concentration, low temperature and lower pressure; hydrogen is not required to be evacuated and can be continuously and circularly used, the consumption of catalysts is reduced greatly, the operation condition is clear, stable and small in fluctuation, the operation safety is enhanced greatly, and the controllability is enhanced; and the reaction conversion rate of the process can reach 100%.

Description

technical field [0001] The invention belongs to the technical field of hindered amine light stabilizers, and specifically relates to a method and a device for producing tetramethylpiperidinol through continuous catalytic hydrogenation. Background technique [0002] Hindered amine light stabilizer is a new type of high-efficiency stabilizer developed by Sankyo Company in Japan in the mid-1970s. It is used for anti-aging of polymer materials such as plastics and rubber. It is 2-4 times that of stabilizers and has good compatibility with many resins. It is currently the fastest growing class of stabilizers. [0003] Tetramethylpiperidone chemical name 2,2,6,6-tetramethyl-4-piperidone (abbreviated as triacetone amine) is the only parent of existing hindered amine light stabilizers, but due to the triacetone amine itself The stability of the powder is not good. Generally, after being placed in the presence of air for 3 to 4 days, it will change from the original milky white to l...

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Problems solved by technology

[0003] Tetramethylpiperidone chemical name 2,2,6,6-tetramethyl-4-piperidone (abbreviated as triacetone amine) is the only parent of existing hindered amine light stabilizers, but due to the triacetone amine itself The stability of the product is not good. Generally, after 3-4 days in the presence of air, it will change from the original milky white to light yellow or even brownish red.

[0006] 2. The chemical reduction method uses aluminum isopropoxide, sodium borohydride, etc. as reducing agents to reduce piperidone to piperidinol, but the reducing agent is more expensive and the post-reaction treatment is more complicated, so it is rarely used in industry;

[0007] 3. Electrochemical reduction method, piperidone is reduced to piperidinol at the cathode of the electrolytic cell, but due to high production energy consumption, complex structure of the electrolytic cell, etc., the industry generally does not use it

[0009] At present, the existing liquid-phase hydrogenation process uses tank or tower reactors for batch production, and the operating conditions for each batch of production are not uniform, that is, the process parameters such as temperature and pressure in the production process of a batch are different from those of other batches. The temperature and pressure process parameters will not be the same in each production process, so that the conversion rate and selectivity of different production batches of reactions are not the same, and the difference is large, resulting in uneven product quality; at the same time, the consumption of solvents and catalysts participating in the reaction is biased. Large, making the production cost high

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