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Pratya Promchana. Geometrical effect on single-site ruthenium and tungsten oxide catalysts. Doctoral Degree(Applied Chemistry). King Mongkut's Institute of Technology Ladkrabang. Central Library. : King Mongkut's Institute of Technology Ladkrabang, .
Geometrical effect on single-site ruthenium and tungsten oxide catalysts
Name: Pratya Promchana
LCSH:
Tungsten
LCSH:
Tungsten oxides
Abstract:
Geometrical effect on single-site ruthenium catalysts, 1,6-Hexanediol (1,6-HD) oxidation to £ -caprolactone (£ -CL) was investigated using (p-cymene)RuCl2(L) complexes with phosphine (LP1_P5) and pyridine (LN1_N5) ligands as catalysts. Despite similar Ru electron density, the activity of (p-cymene)RuCl2(Lp) increases with the decrease in phosphine steric hindrance rather than the electronic properties. The reaction rate correlates with the pocket-size dimension (θC), defined by the (centroid of the p-cymene ring)-Ru-(centroid of 2CI) angle of the (p-cymene)RuCl2(L) complexes. This observation supports an associative interchange mechanism previously proposed by computational studies. The readily accessible θC ≥145°) of these LN complexes results in a similar rate, regardless of different LN ligands. For both complexes, the £-CL selectivity depends only on 1,6-HD conversion. Even though bases significantly enhance the activity, they readily affect the complex stability. The methyl isobutyl carbinol (MIBC) produced during the reaction could competitively react with the Ru catalysts, leading to catalyst deactivation, especially when MIBC : 1,6- HD £ 2 times. For the geometrical effect on single-site tungsten oxide catalysts, acetylene in ethylene-rich feed can be removed via acetylene/ethylene cross-metathesis over W03- supported catalysts at 450 °c, yielding 1,3-butadiene with cyclohexene as a minor product. The catalyst must be treated with ethylene at 600 °c to generate a genuinely active site of tungsten (IV) alkylidene species (W=CH2). The Fl2 treatment decreases surface W=0 concentration, and hence the activity. Raman spectroscopy shows that active single-site W03 species, including mono oxo-W03((0=)W(0-Si)3 and (0=)W(0-Si)4) and dioxo-W03 species (0=)2W(0-Si)2) were generated in 2%W03/Si02, while the W03 cluster and bulk W03 exist in 3-5%W03/Si02 and 7%W03/Si02, respectively. The 5%W03/NaX and 5%W03/NaY provide lower activity due to coke formation over the acid sites. With high surface area and confined surface silanol of 5%WC>3/MCM-41% and 5%W03/SBA-15, in situ TR-EXAFS evidences the formation of only 0=W(0-Si)3. This species provides an isolated W=CH2 site with relatively higher activity and is less prone to coke formation than the W03 cluster in 5%W03/Si02
King Mongkut's Institute of Technology Ladkrabang. Central Library
Address:
BANGKOK
Email:
Lifelong@kmitl.ac.th
Name: Tawan Sooknoi
Role:
Thesis Advisor
Email :
tawan.so@kmitl.ac.th
Modified:
2025-03-24
Issued:
2024-04-29
วิทยานิพนธ์/Thesis
application/pdf
eng
DegreeName: Doctor of philosophy
Level: Doctoral Degree
Descipline: Applied Chemistry
©copyrights King Mongkut's Institute of Technology Ladkrabang
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ใช้เวลา
0.018478 วินาที
Pratya Promchana
| Title | Contributor | Type |
|---|---|---|
| Geometrical effect on single-site ruthenium and tungsten oxide catalysts
สถาบันเทคโนโลยีพระจอมเกล้าเจ้าคุณทหารลาดกระบัง Pratya Promchana | Tawan Sooknoi | วิทยานิพนธ์/Thesis |
Tawan Sooknoi