Synthesis And Performance Of Catalyst For Oxidation Of Cyclopentene To Glutaraldehyde

One of the main sources of cyclopentene is cyclopentadiene,which is also an important by-product in the petrochemical ethylene manufacturing process.As an important highly fine chemical product and intermediate of integrated materials,glutaraldehyde has been widely uesd in the fields of medicine treatment,cell histology,environmental pollution,leather tanning,food and medicinal materials,etc.In China,a large amount of glutaraldehyde is used every year.One step oxidation preparation of glutaraldehyde from cyclopentene as raw material is a very feasible way,which has very important social and economic value,and also provides an effective method for the development and utilization of its by-products.In recent years,homogeneous catalysts such as tungstic acid and heteropoly acid,using hydrogen peroxide as the oxidant,have shown excellent catalytic activity in the oxidation of cyclopentene.However,it is difficult to separate the catalysts and the acid waste solution produced is seriously polluted,which makes it impossible to realize large-scale industrialization.The heterogeneous catalysts mainly include heteropolyacid solid-supported,composite metal oxides,tungsten-containing mesoporous molecular sieve catalysts,etc.Although the separation problem is effectively solved,the dispersion of active components and the problem of slow reaction rate are improved,there are still problems such as limited active load,general mechanical strength and cycling performance.The main work of this paper is to design and synthesize new and efficient catalytic materials,which increase the loading of active components,and inhibit the loss of active components.This paper is expected to to improve or promote the yield of glutaraldehyde in the oxidation reaction of cyclopentene and acquire green and high efficiency cyclopentene catalytic oxidation system:1.PVP-modified SiO₂ microsphere was prepared by the St（?）ber method at first.This paper use ammonium metatungstate as the tungsten source and ultrasonic impregnation method to synthesize WO₃/SiO₂ microsphere samples.It was confirmed that the suitable loading amount of WO₃ can be highly dispersed on the surface of SiO₂ through a series of characterization analysis,mainly in the form of W⁶⁺.The optimal process conditions for cyclopentene oxidation under the action of this catalyst were determined by the single factor experiment.It was found that the catalyst could be recycled 4 times under the system conditions.2.Using ammonium niobium oxalate as niobium source,Nb₂O₅ was loaded onto SBA-15by ultrasonic impregnation method to acquire Nb-SBA-15 catalyst,and its structure was characterized and analyzed.At the same time,the reaction conditions of this system were optimized and the best reaction parameters were obtained.In addition,it was found that the catalytic activity of the catalyst in the ethanol system is basically equivalent to that of tert-butanol.Furthermore,the cycle reaction time was up to 5 times,illustrating its excellent stability.The mechanism of the oxidation of cyclopentene to glutaraldehyde in this system was deduced based on the existing research foundation and literature reports.3.10 wt%WO₃/MWCNTs-COOH was prepared by ultrasonic-impregnation method using ammonium metatungstate as the niobium source.The performance of the catalyst in the selective oxidation of cyclopentene was studied.In addition,different carriers were also replaced to preliminarily explore the influence on the reactivity.