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Heteropoly acid modified ZrO_2 (SiO_2 doped) solid acid catalysts and catalytic polymerization of THF

Author: ShiYanXia
Tutor: LiangLiPing
School: Taiyuan University of Science and Technology
Course: Materials Physics and Chemistry
Keywords: Zirconium dioxide silica phosphotungstic acid tetrahydro-furan polymerization
CLC: O643.36
Type: Master's thesis
Year: 2013
Downloads: 34
Quote: 0
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Abstract


Chemical made outstanding contributions to the progress of mankind. Onthe one hand, human life is inseparable from the chemistry that we creatematerial civilization, on the other hand, many existing chemical processesbrought hazards our living environ-ment that should not beoverlooked-environmental pollution. To curb further deterioration of the survivalof our Earth’s environment and promote the development of green chemicalprocess research, we will turn our attention to the research and development ofenvironment-friendly catalysts. Heteropoly acid modified ZrO2solid acid is anenvironm-entally friendly catalyst and is an excellent catalyst that catalyticimportant tetrahydrofuran polymerization that chemical raw materials.Heteropoly acid form a strong interaction force with the ZrO2carrier.Thusheteropoly acid strong anchored in the surface of the carrier.So that the catalystis easily separated from the product. One to reduce the impact on product quality,Second, the catalyst can also recycle and reuse. ZrO2support poor thermalstability, based on the present study developed ZrO2(doped SiO2) carrier.Effectively improve the carrier a stable performance, and preparation of ZrO2(doped SiO2) supported heteropoly acid catalyst that be applied topolymerization of tetrahydrofuran. Obtained by studying the following mainconclusions:1.There is a strong interaction between the ZrO2support material withheteropolyacids.ZrO2solid acid catalyst modified by phosphomo-lybdicheteropoly acid roasted at high temperature of750℃still showing excellentcatalytic performance.The catalyst with15%PMA loading, reaction conditionsof40℃for20h, showed high polymer yield of49%, a number averagemolecular weight of2261.2. we come to a conclusion that a small amount of SiO2significantlychange the crystallization behavior of ZrO2material under the condition of high temperature processing. In addition, different preparation methods will result inmaterials with different properties. Comprehensive comparison found that thecarrier1-(b) has better performance than others. It was prepared as follows:zirconium oxychloride (ZrOCl2) with ammonium hydroxide.we introduced SiO2into the gel by adding aqueous solution of sodium silicate (Na2SiO3). TheZrO2-SiO2gel was then washed and dried at120℃overnight to obtain azirconia powder that was reserved.Compared with two-step method,1-(b)eliminated the step of pre-hydrolysis. It is simple, saving time and energy.3. Heteropoly tungstate modified-ZrO2(doped SiO2) is a highly efficientand stable solid acid catalytic materials.20PMZS-750,under the reactionconditions of40℃for22h, showed high polymer yield of51%, a numberaverage molecular weight of1900to2000. During recycling for6times,noobvious activity loss was observed,and under the reaction conditions of40℃for22h,20g of THF,1.0g of catalyst, showed average polymer yield of about30%.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalyst
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