Research On Green Catalytic Oxidation And Modification Based On Titanium Silicon Zeolite

Nowadays,chemical industry is developing rapidly,but at the same time it has caused environmental and energy crises,seriously affecting and hindering the healthy and rapid development of the chemical economy.Oxidation reaction is one of the most basic reactions in chemical technology.How to realize its greening is one of the hot research topics in green chemistry.Hydrogen peroxide,as a clean oxidant,has broad application prospects in green catalytic oxidation due to its high atom utilization rate and environmental friendliness.This thesis is devoted to the development of clean oxidation technology and high-activity,highselectivity structural design of the catalyst,and to conduct green catalytic oxidation and catalytic modification studies based on titanium-silicon molecular sieve.The main research contents are as follows:1.In order to solve the key problems of solvent hazards and complex processes common in traditional methods,a clean and efficient production process of hydroxylamine hydrochloride through solvent-intensified processes has been developed.Hydrogen peroxide,ammonia and methyl ethyl ketone are catalyzed by Ti-MWW in the membrane reaction unit to achieve the ammoximation reaction.After dehydration and deamination,butanone oxime is hydrolyzed with hydrochloric acid in the reaction rectification device to generate hydroxylamine hydrochloride.The process achieves the conversion of butanone?97%?,the selectivity of butanone oxime?100%?,the yield of hydroxylamine hydrochloride?91.6%?and the recovery of butanone?85.1%?.The recycling of materials achieves atomic economy,and the coupling enhancement of the membrane reaction unit,the process deamination unit and the reactive distillation unit realizes a highly efficient continuous process.Through the use of Aspen Plus v10 for simulation,the entire process runs stably.By optimizing the hydrogen peroxide content at the outlet of the membrane reaction and the ammonia content at the bottom of the deamination tower,it can meet the requirements of industrialization.2.In the study of one-step hydroxylation of benzene and hydrogen peroxide to produce phenol,a series of single-components were prepared by using macroporous Ti-mordenite?Ti-MOR?as a carrier and introducing different metal oxides by ultrasonic impregnation,the two-component metal compound catalyst and its catalytic activity.The VOx/Ti-MOR twocomponent catalyst screened by the experiment can obtain a phenol yield of 60% and a selectivity of 97%.This synergistic catalytic system composed of metal oxides and zeolites allows the activation of hydrogen peroxide and benzene hydroxylation reactions to occur simultaneously in two different types of active centers,and at the same time by fixing the metal oxides in an effective adsorption performance and significant specific surface area Suitable carrier to improve the catalytic performance of metal oxides.3.By combining titanium-silicon molecular sieve with Keggin structure vanadium substituted polyoxometallate H5PMo10V2O40,a large pore polyoxometalate ion hybrid catalyst PMoV₂/Ti-MOR was prepared.The catalyst shows excellent catalytic activity in the reaction of 2,5-dichlorophenol prepared by oxidation of p-dichlorobenzene with hydrogen peroxide,and it is also quite stable and reusable.SEM,TEM,N2 adsorption and other instruments were used to characterize the synthesized materials,focusing on the catalyst composition,structure and catalytic reactivity.Compared with the bulk H5PMo10V2O40,the supported PMoV₂/Ti-MOR catalyst increases the specific surface area,reduces the amount of active components,effectively overcomes the problems of small bulk specific surface area,no pores,etc.,and enhances the catalytic activity of heteropoly acid.Under the experimental conditions?75?,the reaction ratio of H₂O₂ to p-dichlorobenzene was 1: 3,4 h?,the yield of 2,5-chlorophenol was 24.8%.