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Mesoporous MO/ZrO2-La2O3Solid Base Catalyst and Catalytic Activity of Transesterification

Author: WangChengYuan
Tutor: DongGuoJun
School: Harbin Engineering University
Course: Applied Chemistry
Keywords: Mesoporous zirconia K2O doping vario-property t-ZrO2
CLC: TQ426.83
Type: Master's thesis
Year: 2013
Downloads: 18
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Abstract


In this thesis, mesoporous zirconia （ZrO2） were synthesized by hydrothermal andimmersion process with a cationic surfactant C16H33（CH3）3NBr （CTAB） as template.After that, the mesoporous solid base catalysts of MgO/ZrO2and MgO/ZrO2-La2O3-xwere prepared with ZrO2, MgO and La2O3as the carrier, active component andadditives, respectively. On this basis, by immersing those catalysts respectively in theKNO3or KOH solution,the mesoporous catalysts K2O-x/ZrO2-MgO andK2O-x/ZrO2-MgO-La2O3were prepared. The catalytic activities were evaluated in thesynthesis of di-2-ethylhexyl carbonate （DEHC） from dimethyl carbonate （DMC） and2-ethylhexanol （EHOH）. The physical and chemical properties of the catalysts werecharacterized by XRD, Raman spectra, CO2-TPD, BET method, SEM and TEM. Andthe influence of the potassium content, the calcination temperature, and the additionof magnesium or lanthanum on the crystal structure and basicity of the catalyst werecomparatively investigated.The mesoporous MgO/ZrO2and MgO/ZrO2-La2O3-x characterization resultsindicated that there is main tetragonal phase for the catalysts with typical mesoporousstructure, which implies that MgO is highly dispersed on tetragonal phase ZrO2forming a stable MgO/ZrO2solid solution. When the Mg/Zr molar ratio is0.45, MgOcan steady simultaneously the surface phase and bulk phase of t-ZrO2. La2O3is able topromote the dispersion of MgO covered on ZrO2surface, which leads to the exposureof the alkalescence of partial ZrO2. Additionally, the grain refinement, the specificsurface area are increased. When the content of La2O3is0.7%, there is the largestcatalytic activity.For mesoporous K2O-x/ZrO2-MgO and K2O-x/ZrO2-MgO-La2O3catalysts, whenthe load of KNO3or KOH is0.2, the resulting sample exhibits a typical mesoporousstructure. With the increasing of the content of potassium, the partial channels areblocked, which caused the changes of the specific surface area, pore diameter andchannels. With the increasing of the content of KNO3, the structures of the catalystsare gradually changed from surface single dispersion to K2O sandwich, thus the weakbasic site and medium strong basic site of ZrO2are covered. As the content of KOHincreases, CO2-TPD corresponding to medium strong basic site is weakened with the increasing of MgO desorption peak. La2O3is able to promote the dispersion of MgOcovered on ZrO2surface and the grain refinement.The catalytic performances were evaluated in the synthesis of di-2-ethylhexylcarbonate （DEHC） from dimethyl carbonate （DMC） and2-ethylhexanol （EHOH）. Inorder to characterize the synthetic product, FT-IR and gas chromatography was used.

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CLC: > Industrial Technology > Chemical Industry > Reagents and the production of pure chemicals > Catalyst ( catalyst ) > Metal catalysts > Multi - metal catalyst
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