Study on the catalytic properties of aluminophosphate type molecular sieves알루미노포스페이트 계열 분자체의 촉매특성에 관한 연구

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Aluminophosphate type molecular sieves including ALPO-5, SAPO-5 and VAPO-5 were synthesized by hydrothermal crystallization technique and characterization of SAPO-5 and VAPO-5 catalysts was carried out. The crystallization rate of ALPO-5 showed sigmoid form and the length/width ratio of ALPO-5 crystals increased as the water content of initial gel increased. SAPO-5 showed much higher cation exchange capacity and catalytic activity for the acid catalyzed reactions such as isomerization, alkylation and disproportionation than the ALPO-5. Although the cation exchange capacity of SAPO-5 increased with the silicon content of SAPO-5(up to about 1 si/U.C.), the SAPO-5 having about 1 to 3 si/U.C. showed nearly constant cation exchange capacity. The EPR spectrum of cupric ion in Cu-SAPO-5 indicated that all cation sites could be equivalent. The EPR spectrum of sulfur dioxide anion radical formed on H-SAPO-5 suggested that the adsorption sites for the radical were also equivalent. These equivalences of cation or adsorption sites are probably due to the simple framework structure of SAPO-5. Most of vanadium in as-synthesized VAPO-5 was V(IV) state and was oxidized to V(V) by calcination in air. The vanadium in VAPO-5 seemed to be distributed in highly dispersed state and showed reversible redox properties changing it``s oxidation state easily between V(IV) and V(V). As the vanadium content of VAPO-5 increased, the weight loss in TGA due to the template molecules (tri-n-propylamine) shifted to higher temperature, suggesting some interaction between VAPO-5 and template molecules. This interaction, probably due to the acidity of VAPO-5 favors the interpretation that V(IV) was incorporated into the hypothetical P(V) site rather than Al (III) site in VAPO-5. TGA results and the facts that the unit cell dimensions were changed by incorporating vanadium into ALPO-5 and the vanadium in VAPO-5 had tetrahedral coordination suggested that the vanadium was probably sited in The tetra...
Advisors
Chon, Hak-Ze전학제
Description
한국과학기술원 : 화학과,
Publisher
한국과학기술원
Issue Date
1990
Identifier
61426/325007 / 000835369
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 화학과, 1990.2, [ x, 140 p. ]

URI
http://hdl.handle.net/10203/31331
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=61426&flag=dissertation
Appears in Collection
CH-Theses_Ph.D.(박사논문)
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