CS-Salen-Mn-type composite catalyst based on natural polymer chitosan and preparation method

Abstract

The invention discloses a composite catalyst which is prepared by using an amino rich on the surface of natural polymer chitosan (CS for short) to be condensed with a formyl group in salicylaldehyde so as to form an imine ligand, and coordinating with manganese acetate and a preparation method, and belongs to the field of chemical industries. The composite catalyst is named as: CS-Salen-Mn, and astructural formula of the CS-Salen-Mn-type composite catalyst is as shown in Figure 1, wherein CS is used as a parent; the salicylaldehyde is a ligand; acetic acid is an organic solvent; Mn(OAc)2.4H2Ois used as a coordination center; an Mn atom in the CS-Salen-Mn is directly connected with an N atom forming the imine ligand in the chitosan by a coordination bond. The CS-Salen-Mn-type composite catalyst based on the natural polymer chitosan is designed and prepared by using a condensation and coordination technology. The composite catalyst CS-Salen-Mn has the advantages of simple preparation process, good reaction specificity, and high methyl phenyl sulfide oxidation reaction selectivity, can be recycled repeatedly and is pollution-free in a reaction process.

Description

technical field [0001] The invention belongs to the field of chemical industry and relates to a CS-Salen-Mn type composite catalyst based on natural polymer chitosan and a preparation method. Background technique [0002] In 1990, Jacobsan et al. designed a Salen-Mn complex with the same characteristics as metalloporphyrin compounds in terms of electronic and catalytic activity, and used it in catalytic oxidation reactions. Innovate and make some progress. However, for the homogeneous Salen-Mn catalyst, although it is difficult to separate the substrate during the catalytic process, it is not conducive to repeated use, which greatly limits its use. In addition, homogeneous Salen-Mn catalysts have dimerization deactivation during the reaction process. Therefore, more and more people choose to immobilize homogeneous Salen-Mn catalysts on organic or inorganic supports to prepare heterogeneous catalysts. In order to solve the problem that Salen-Mn is not easy to recycle as a h...

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Problems solved by technology

However, the surface of the mesoporous silicon composite material has a high concentration of hydroxyl groups and has strong hydrophilicity. In the catalytic reaction, the hydrophilic product is easily adsorbed on the surface and pores of the silica, which leads to the failure of the catalyst during recycling. Severely inactivated, and most of them use post-grafting or dipping method, the operation process is complicated, and the experiment cycle is long

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