Study on the Preparation of Zeolite with Core-Shell Structure and Indirect Synthesis of Cyclohexanol from Cyclohexene
|School||Hebei University of Technology|
|Keywords||core-shell structure ZSM-5 hydrothermal synthesis cyclohexanol cyclohexylformate one-pot synthesis|
In recent years, core-shell structure materials are holding a great attention because of itsparticular configuration and physicochemical properties. During the catalytic research, it can beused in multifunctional catalyse. Multi-step catalytic reaction will be achieved in microcosmiclimit space by the different catalytic capability. And it show a different nature of separate nuclearor shell catalyst in some cases.Core-shell structure materials SiO2@ZSM-5,α-Al2O3@ZSM-5 and ZrO2@ZSM-5 weresynthesized by the in situ hydrothermal synthesis. The XRD characterization results reveal thatthe crystals on the substrate surface have ZSM-5 zeolite structure after the hydrothermal reaction.The SEM observations show that the microstructure of ZSM-5 zeolite films on differentsubstrates is different. ZSM-5 zeolite membranes have the best growth effect on theα-Al2O3surface. A tight, continuous and uniform ZSM-5 films was obtained. Analyses have indicatedthat because of the existence of -Al-O-Al- bonds between ZSM-5 andα-Al2O3.Core-shell structure materialsα-Al2O3@CoAPO-5 was prepared by hydrothermal synthesis,using pseudo-boehmite, 85% phosphoric and tetrahydrate cobalt acetate as raw material, and2-（2 amino） ethanol as template. XRD，SEM show that a uniform CoAPO-5 molecular sievesmembrane about 50-100μm thickness grow on the surface ofα-Al2O3. CoAPO-5 granules haveregular six prism colour and preferable crystallinity.The catalytic synthesis of cyclohexanol from cyclohexene via cycolhexyl formate wasinvestigated in an autoclave. The factor influencing the esterification of cyclohexene with formicacid and hydrolysis of cyclohexyl formate was studied respectively, and the reaction conditionswere optimized. The one-pot synthesis of cyclohexanol from cyclohexene via cyclohexylformate was investigated and the highest cyclohexanol yield was up to 40%, far beyond theresults of direct hydration of cyclohexene. HZSM-5, catalyst for one-pot synthesis, lost itsactivity gradually with the used times increasing because the acid sites on the surface were coverd by the adsorbed organic compounds. The regeneration of the deactivated HZSM-5 couldbe done by calcination at 550℃in atmospheric circumstance.