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New pillared zirconium phosphate materials synthesis and catalytic applications

Author: LiYing
Tutor: LeYingHong
School: Fudan University
Course: Physical and chemical
Keywords: pillared layered metal phosphate sulfonation hydroquinone alkylation α-pinene isomerization DTBPy acidity accessibility asymmetric transfer hydrogenation
CLC: O611.3
Type: Master's thesis
Year: 2009
Downloads: 216
Quote: 1
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Abstract

Layered metal phosphates,among numerous layered materials,have received considerable attention because of unique properties which lend themselves to various potential practical uses.Layered zirconium phosphate material is one of the typical layered phosphate materials.It is deemed as a kind of potential material in catalytic field for its thermal stablility of the layers and anti-acid properties,and its structure and catalysis site being designable.In spite of the considerable effort devoted to the design of layered phosphate materials,exploring new experimental synthesis route and applications in catalytic field is necessary.In this work,a mesoporous layered zirconium phosphate material was synthesized by a novel co-template method of using of a surfactant expanded zirconium phosphate for the formation of silica galleries into the interlayer space.And the catalytic active sites were introduced on the materials during the hydrolyzing process by co-condensation.This new kind of layered zirconium phosphate was expected to be a good solid catalyst in liquid reaction with its mesoporous structure,which is related to easy diffusion and access of large molecules to the active sites,and its designable active sites.We systematically studied the synthesis,introduction of active sites and surface modification of this silica-pillared layered zirconium phosphate and applied as catalyst in alkylation of hydroquinone with tert-butanol,isomerization reaction ofα-pinene and asymmetric transfer hydrogenation of hypnone.The main results of the work are as follows:1.Phenyl-functionalized pillared zirconium phosphates were synthesized and then the PhSO₃^2- functionalized corresponding materials were synthesized through sulfonation.The structure of the materials was characterized and it was found that the amount of cetylamine co-template and silica source added during synthesis process influenced its catalytic performance a lot in alkylation of hydroquinone with tert-butanol reaction.ZrP-0.4-2-10%-PhSO₃H showed best catalytic performance with 85.4%conversion and 58.5%yield,which was much better than SiO₂-pillared zirconium phosphates,and the reuse ability of ZrP-0.4-2-10%-PhSO₃H was good.The amount of accessible acid sites was tested by DTBPy probe and it was positive related to the catalytic performance of the catalysts.This kind of catalysts performed well in isomerization reaction ofα-pinene.The conversion ofα-pinene was 96.4%,and yield the products with industrious value was 64.9%over ZrP-0.4-2-10%-PhSO₃H,which was much better than SiO₂-pillared zirconium phosphates.However,the reuse ability in this reaction was not good as expected.2.Alkyl-or phenyl-functionalized pillared zirconium phosphates were synthesized and applied in alkylation of hydroquinone with tert-butanol reaction.It was found that the catalytic performances were enhanced by introducing organic pieces on the materials,and methyl-functionalized pillared zirconium phosphate performed best with 80.1%conversion and 48.9%yield.The amount of total acid sites and of the large molecule accessible ones was measured by i-propanol dehydration and adsorption of DTBPy,respectively.The catalytic performance order of catalysts with different functional pieces was not related to the total acid sites amount,but was the same of the accessible acid sites amount,which means that the accessibility of acid sites to large molecule dramatically affects the reactivity of this kind of materials.The reuse ability was also test.3.Chiral diaminocyclohexane functionalized pillared zirconium phosphate was synthesized,characterized and applied in asymmetric transfer hyrogention.When the S/C was 100 and the reaction temperature was 83℃,the heterogeneous catalyst （ZrP-Ru） showed 64%conversion of hypnone with 35%ee after 24h-reaction,and 75%conversion of hypnone with 36%ee after 48h-reaction.Compared with the catalytic activity of homogeneous catalyst under the same reaction condition,the conversion was lower,but the ee value enhananced by 21%.It was found temperature has considerable affect on this reaction.

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