Method for synthesizing N-methylmorpholine-N-oxide (NMMO) through catalytic oxidation

Abstract

The invention belongs to the technical field of catalytic oxidation synthesis, and discloses a method for synthesizing NMMO through catalytic oxidation. Under the conditions of normal pressure and a temperature of 40-90 DEG C, alkaline porous carbon is used as a catalyst to catalyze NMMO and persulfate to react so as to synthesize NMMO, wherein reaction time is 2-8 h, and the use amount of the catalyst is 0.1-5 wt.% of the mass of a reaction solution. According to the method, persulfate is used as an oxidizing agent to replace traditional H2O2, and alkaline porous carbon is used as the catalyst to replace a homogeneous alkali solution; compared with H2O2, persulfate is higher in oxidability, more convenient to transport and store and low in cost; alkaline porous carbon is easier to separate and purify subsequently compared with the homogeneous alkali solution, has rich pore structures and various functional groups on the surface, can effectively relieve reaction conditions and improvesthe activity of persulfate for catalytic oxidation synthesis of NMMO; and the method is simple in process, easy to operate and suitable for industrial production.

Description

technical field [0001] The invention belongs to the technical field of catalytic oxidation synthesis, and in particular relates to a method for synthesizing N-methyl morpholine oxide by catalyzing persulfate oxidation based on basic metal-modified nitrogen-doped porous carbon. Background technique [0002] N-methylmorpholine oxide (NMMO) is a tertiary amine oxide, which is commonly used as a solvent for the production of Lyocell fibers. As a green fiber production process, Lyocell fiber technology will exceed the output of polyester, the largest variety of chemical fiber at present, and the economic benefits will be significant, which will inevitably drive the further development of NMMO. Therefore, the development of an efficient synthesis process for NMMO is of great practical significance to the development of the textile industry, and it also provides raw material support for the rapid development of Lyocell fibers in my country. At present, the main process for industr...

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Problems solved by technology

[0003] However, the problems and defects in the prior art are that (1) the oxidizing agent H2O2 is very easily Decomposition, difficult to store, to obtain high yield of N-methyl morpholine oxide often need to add excess H2O2, resulting in a large loss of oxidant, increasing the production Cost and production risk; (2) In this synthesis process, on the one hand, the synthesis reaction and the H2O2 decomposition reaction will produce a large amount of water, and on the other hand, due to the use of The best is 30% H2O2, so that a large amount of water will be brought into the raw material, and the separation and purification pressure of subsequent vacuum distillation and azeotropic distillation will be increased, while Long-term rectification operation will also affect the quality of N-methylmorpholine oxide; (3) the production of this process will produce more wastewater, which will increase the cost of wastewater treatment; (4) traditionally, tertiary amine oxides generally use homogeneous catalysts Carry out catalytic reaction, the reaction conditions are relatively harsh, the catalyst recovery is difficult, and there are many side reactions, so that the yield of N-methyl morpholine oxide is low

[0004] Therefore, in view of the deficiencies in the existing industrial synthesis of NMMO, the key to solving the above problems and defects is: (1) develop a highly efficient oxidant to replace H 2O2, reducing the introduction of water in the whole process, and solving the difficulty of storage and transportation of H2O2 Problem; (2) develop an efficient heterogeneous alkaline catalyst to replace the traditional homogeneous alkaline solution catalyst, realize the effective recovery of the catalyst and avoid the introduction of impurities

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