Sythesis Of α、δ-MnO₂and Their Catalytic For Deep Catalytic Oxidation Of O-xylene

Deep catalytic oxidation that can directly oxidize benzene pollttation into CO2and H2Ois one of the most effective and promising research methods. The effective, based onconvenience, simple synthetic route and low-priced manganese oxides are regarded as one ofimmportant catalyst. Therefore preparation of the catalyts with high activity, and to be used inthe complete catalytic oxidation of benzene hydrocarbons is a very significant subject of thisresearch.In this paper, α, δ-MnO2were used prepared using KMnO4, n-butylamine and KMnO4、t-butyiamine. α, δ-MnO2were used for o-xylene deep catalytic oxidation. The catalyticactivities were evalued in term of o-xylene conversion and the yileld of CO2. X-ray diffraction(XRD), Scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET),Thermogravimetry (TG), and Energy dispersive spectrometer (EDS) were used to characterizethe catalyts. The main reslts are as follows:(1) Mesoporous α-MnO2were easily prepared using KMnO4and amine (ethylamine,ethanediamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, cyclohexylamine)as precursors via Interface synthesis without any template. The effects such as different amine,mole ratio, concentration of reactants, different solvents, solvent quantity and roastingtemperature on the structure and activity of the catalysts were investigated. Mesoporous α-MnO2preparate with amine reducibility, solubility, polarity, space structure and other factors.Thepreparation of mesoporous α-MnO2catalytic activity for the best conditions: Mesoporousα-MnO2was easily prepared using KMnO4and n-butylamine as precursors via interfacesynthesis between H2O and CH2Cl2without any template at room temperature for24h. Thestructure characterizations indicated a good mesoporous structure for as-prepared α-MnO2withan adsorption average pore diameter of19.082nm, and Brunauer–Emmett–Teller specific surfacearea of250.671m2g-1. α-MnO2is still mesoporous materials after400℃calcination.Brunauer–Emmett–Teller specific surface area of185.543m2g-1. n-Butylamine adsorpted on thesurface of the manganese dioxide, as the template agent oriented form four prisms. The resultsshowed that catalyst can make o-xylene completely transformed to CO2and H2O at210℃.After500℃calcination is still the mesoporous structure, thus the thermal stability of this method isthe preparation of catalyst.(2) δ-MnO2were successfully synthesized by KMnO4as oxidant, t-butylamine asreducing agent. The influence of the reaction method, reaction temperature, hydrochloric acid reflux and calcination temperature on the product phase and morphology of obtained δ-MnO2nanowires were discused. Explores the conditions of the preparation of the δ-MnO2, theδ-MnO2and α-MnO2conversion conditions, and the decomposition rate of o-xylene andcarbon dioxide production rate two aspects of the performance of the comprehensive analysisof the above two kinds of catalysts. Experiment of preparation of the δ-MnO2is associatedwith the reducibility of reducing agent, reaction rate. δ-MnO2into α-MnO2can improve thereaction temperature(improve the reaction rate), hydrochloric acid (H+replace K+), improvethe roasting temperature(δ-MnO2into thermal stability of the α-MnO2) implementation phasetransformation.This dissertation was supported by the National Natural Science Founadation of China(No.21147004), the National Natural Science Founadation of Hebei (No. B2013205100) andthe Science Foundation of Hebei Normal University (No. L2010Z06).