• Journal of the Korean Magnetic Resonance Society
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• v.6 no.1
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• pp.20-37
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• 2002

MnAPSO-34 and Mn-impregnated SAPO-34(Mn-SAPO-34) sample were prepared with various manganese contents and studied by electron spin resonance(ESR) and electron spin echo modulation(ESEM). Electron spin echo modulation analysis of 0.07mo1 ％ Mn(relative to p) in MnAPSO-34 with adsorbed D$_{2}$O shows two deuteriums at 0.26 nm and two at 0.36 nm from Mn. This suggests that two waters hydrate an MnO$_{4}$ configuration with a D-O bond orientation for the waters as expect for a negatively charged site at low manganese content (0.1 mol％), the ESR spectra of MnAPSO-34 and MnH-SAPO-34 exhibit the same parameters(g 2.01 and A 89 G), but the spectra obtained from MnAPSO-34 samples are better resolved. The decomposition temperature of as-synthesized MnAPSO-34 were in the range of 200-600 $^{\circ}C$ of the morpholine which is 12 $^{\circ}C$ higher than that in as-synthesized MnH-SAPO-34. Infrared spectra showed that the position of a band at 3450 $cm^{-1}$ / shifted about 15 $cm^{-1}$ / toward higher energy in MnAPSO-34 versus MnH-SAPO-34. The modulation depth of the two-pulse ESE of MnAPSO-34 with adsorbed D$_{2}$O is deeper than that of MnH-SAPO-34 with adsorbed D$_{2}$O. Three-pulse ESEM of MnAPSO-34 and MnH-SAPO-34 with adsorbed deuterium oxide shows that the local environments of manganese in the hydrated samples are different, suggesting that Mn(II) is framework substituted in MnAPSO-34 since it obviously occupies an extraframework position in MnH-SAPO-34.

• Journal of the Korean Magnetic Resonance Society
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• v.9 no.1
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• pp.1-20
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• 2005

Vanadium-incorporated aluminophophate molecular sieve VH-SAPO-11 has been studied by electron spin resonanace (ESR) and electron spin echo modulation (ESEM) spectroscopies to determine the vanadium locatin and interaction with various adsorbate molecules. As-synthsized VH-SAPO-11 contains only vanady1 species with distored octahral coordination. After calcinations in $O_2$ and exposure to moisture, only species A is observed with reduced intensities. Species A is suggested as a VO$(H_2O)_2^{2+$} complex coordinate to three framwork oxygen bonded to aluminum. When calcined, hydrate VH-SAPO-11 is dehydrated at elevated temperature, species A loses it water ligands and transforms to $VO^{2+}$ ions coordinated to three framework oxygens (species B). Species B reduces its intensities significantly after treatment with $O_2$at high temperature, thus suggesting oxidation of $v^{4+}$to $v^{5+}$. When dehydrated VH-SAPO-11 contacts with $D_2O$ at room temperature, the ESR signal of species A is observed. This species assumed as a $VO(O_f)_3(D_2O)_2$, by considering 3 framework oxygens. Adsorption of deuterated methanol on dehydrated VH-SAPO-11 results in another new vanadium species D, which is identified as a $VO(CD_{3}OH)$ complex. When deuterated ethanol is adsorbed on dehydrated VH-SAPO-11, another new vanadium species E identified as a $VO(C_{2}H_{5}OD)^{2+}$, is observed. When deuterated propanol is adsorbed on dehydrated VH-SAPO-11, a new vanadium species F identified as a $VO(C_{3}H_{7}OD)$, is observed. Possible coordination geometries of these various complexes are discussed.

• Journal of the Korean Magnetic Resonance Society
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• v.11 no.2
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• pp.95-109
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• 2007

Vanadium-incorporated aluminophosphate microporous molecular sieve VH-SAPO-42 has been studied by electron spin resonance(ESR) and electron spin-echo modulation (ESEM) spectroscopies to determine the vanadium location and interaction with various adsorbate molecules. The results are interpreted in terms of V(IV) ion location and coordination geometry. Assynthesized VH-SAPO-42 contains only vanadyl species with distorted octahedral or trigonal bipyramidal coordination. Vanadium incorporated into H-SAPO-42 occupied extra-framework site. After calcinations in $O_2$ and exposure to moisture, only species A is observed with reduced intensities. Species A is identified as a $VO(H_2O)_2^{2+}$ complex coordinated to three framework oxygen atoms bonded to aluminum. When hydrated VH-SAPO-42 is dehydrated at elevated temperature by calcination, species A loses its water ligand and transforms to $VO^{2+}$ ions coordinated to three framework oxygens (species B). Species B reduces its intensities significantly after treatment with $O_2$ at high temperature, thus suggesting oxidation of $V^{4+}$ to $V^{5+}$. When dehydrated VH-SAPO-42 makes contact with $D_2O$ at room temperature, the ESR signal of species A is regained. The species is assumed as a $VO(O_f)_3(D_2O)_2$ by considering three framework oxygens. Adsorption of deuterated methanol on dehydrated VH-SAPO-42 results in another new vanadium species D, which is identified as a $VO(CD_3OH)_2$ complex. When deuterated ethylene is adsorbed on dehydrated VH-SAPO-42, another new vanadium species E identified as a $VO(C_2D_4)^{2+}$, is observed. Possible coordination geometries of these various complexes are discussed.

• Polymer(Korea)
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• v.37 no.3
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• pp.379-386
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• 2013

SAPO-11 was applied for the first time to the catalytic pyrolysis of miscanthus and random polypropylene (random PP). Thermogravimetric analysis confirmed that SAPO-11 promoted the dehydration of miscanthus while suppressing the formation of char. In the pyrolysis of random PP, the decomposition temperature and activation energy were reduced by using a catalyst. A large fraction of levoglucosan, which was the main oxygenate product from the non-catalytic pyrolysis of miscanthus, was converted to high value-added products, such as furans, phenolics and aromatics using SAPO-34. The catalytic pyrolysis of random PP produced gasoline- and diesel-range hydrocarbons.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.684-689
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• 2010

We synthesized a variety of SAPO catalysts with various structure directing agents by the hydrothermal method and applied them to the D-xylose dehydration. Single or mixtures of organic amines, viz. tetraethylammonium hydroxide(TEAOH), dipropylamine(DPA), diethylamine(DEA), morpholine and diethanolamine(DEtA) were used as structure directing agents. The $N_2$-isotherm, $NH_3$-temperature programmed desorption(TPD) and temperature programmed oxidation(TPO) were conducted to characterize SAPO catalysts. Among tested SAPO catalysts, the SAPO-34 synthesized with morpholine showed the highest furfural yield. The external surface area as well as the surface concentration of acid sites appeared to affect the catalytic activity for the dehydration of xylose into furfural.

• Proceedings of the Korean Magnetic Resonance Society Conference
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• 2002.08a
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• pp.80-80
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• 2002

MnPSO-34 and Mn-impregnated SAPO-34 (Mn-SAPO-34) sample were prepared with various manganese contents and studied by electron spin resonance (ESR) and electron spin-echo modulation (ESEM). Electron spin-echo modulation analysis of 0.07mol ％ Mn(relative to p) in MnAPSO-34 with adsorbed D$_2$O shows two deuteriums at 0.25 nm and two at 0.36 nm from Mn. This suggests that two waters hydrate an MnO4 configuration with a D-O bond orientation for the waters as expect for a negatively charged site at low manganese content (0.07 mol％), the ESR spectra of MnAPSO-34 and MnH-SAPO-34 exhibit the same parameters (g 2.02 and A 87 G), but the spectra obtained from MnAPSO-34 samples are better resolved. TGA of as-synthesized MnAPSO-34 shows that the decomposition temperature in the range 200-$600^{\circ}C$ of the morpholine is 12$^{\circ}C$ higher than that in as-synthesized MnH-SAPO-34. Infrared spectra shows that the position of a band at about 15 cm-1 toward higher energy in MnAPSO-34 versus MnH-SAPO-34. The modulation depth of the two-pulse ESE of MnAPSO-34 with absorbed D$_2$O is deeper than that of MnH-SAPO-34 with absorbed D$_2$O. Three-pulse ESEM of MnAPSO-34 and MnH-SAPO-34 with absorbed deuterium oxide shows that the local environments of manganese in the hydrated samples are different, suggesting that Mn(II) is framework substituted in MnAPSO-34 since it obviously occupies an extra-framework position in MnH-SAPO-34

• Applied Chemistry for Engineering
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• v.34 no.5
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• pp.548-555
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• 2023

SAPO-34 catalysts were modified with polyethylene glycol (PEG) and Pb to improve their catalytic lifetime and selectivity for light olefins in the conversion of dimethyl ether to olefins (DTO). Hierarchical SAPO-34 catalysts and PbAPSO-34 catalysts were synthesized according to changes in the molecular weight of PEG (M.W. = 1000, 2000, 4000) and the molar ratio of Pb/Al (Pb/Al = 0.0015, 0.0025, 0.0035), respectively. By introducing PEG into the SAPO-34 catalyst crystals, an enhanced volume of mesopores and reduced acidity were observed, resulting in improved catalytic performance. Pb was successfully substituted into the SAPO-34 catalyst frameworks, and an increased BET surface area and concentration of acid sites in the PbAPSO-34 catalysts were observed. In particular, the concentrations of the weak acid sites, which induce a mild reaction, were increased compared with the concentrations of strong acid sites. Then, the P2000-Pb(25)APSO-34 catalyst was prepared by simultaneously utilizing the synthesis conditions for the P2000 SAPO-34 and Pb(25)APSO-34 catalysts. The P2000-Pb(25)APSO-34 catalyst showed the best catalytic lifetime (183 min based on DME conversion > 90%), with an approximately 62% improvement compared to that of the unmodified catalyst (113 min).

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.559-567
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• 2008

SAPO-34 is a well-known catalyst for methanol to olefins (MTO) process, but is rapidly deactivated by coke formation. It is necessary to improve the catalyst lifetime of SAPO-34 for MTO process. In the present work, SAPO-34 catalysts were synthesized with a variety of structure directing agent, and the physicochemical properties of the catalysts were examined by $N_2$-isotherm, XRD, SEM, and $NH_3$-TPD. It was found that mixed structure directing agents, especially DEA and TEAOH, gave well developed SAPO-34 crystal structure and reduced the crystal size and moderated acidity of SAPO-34 under the same synthetic conditions as that of various structure directing agents. Also, we could find that SAPO-34 catalyst prepared by mixed templates of DEA and TEAOH had the superior catalytic activity and the longer lifetime in MTO reaction.

• Journal of the Korean Magnetic Resonance Society
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• v.5 no.2
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• pp.73-90
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• 2001

Vanadium-doped H-SAPO-34 samples were prepared by a high-temperature solid-state reaction between SAPO-34 and the paramagnetic V(Ⅳ) species and characterized carefully by EPR and Electron Spin-Echo Modulation(ESEM) studies. The paramagnetic vanadium species generated in both V$_2$O$\_$5/ and VOSO$\_$4/ of SAPO-34 have the same narrow range of g value fur vanadium species assigned to VO$\^$2+/ inferred from the isotropic EPR spectrum at 293 K. The EPR and ESEM data indicate that the V(Ⅳ) species exist as a vanadyl ion either as [V(Ⅳ)]O$\^$2+/ or V$\^$4+/. The [V(Ⅳ)]O$\^$2+/ species seems to be more probable because SAPO-34 having a low negative framework charged and more positively charged species like V$\^$4+/can not be easily stabilized. Tetravalent vanadium ion in vadium-doped H- SAPO-34 can only be observed at the temperature lower than 77 K, while the vanadyl ion, VO$\^$2+/in the activated sample of VH-SAPO-34 can produce the ion even at room temperature. After the adsorption of methanol, ethanol, propanol or ethene to the VH-SAPO-34, only one molecule coordinate to [V(Ⅳ)]O$\^$2+/ was observed in EPR and ESEM spectra.

• Journal of the Korean Magnetic Resonance Society
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• v.9 no.2
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• pp.138-154
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• 2005

Vanadium-incorporated aluminophosphate molecular sieve $VO^{2+}-SAPO-5$ was studied by electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopies to determine the vanadium structure and interaction with various adsorbate molecules. It was found that the main species at low concentration of vanadium is a monomeric vanadium units in square pyramidal or distorted octahedral coordination, both in oxidation state (IV) for the calcined hydrated material and in oxidation state (V) for the calcined material. After calcinations in $O_2$ and exposure to moisture, only species A is observed with reduced intensities. It is suggested as a $VO(H_2O)_3^{2+}$ complex coordinated to two framework oxygen bonded aluminum. When calcined, hydrated $VO^{2+}-}SAPO-5$ is dehydrated at elevated temperature, a species loses its water ligands and transforms to $VO^{2+}$ ions coordinated to two framework oxygens (species B). Species B reduces its intensity, significantly after treatment with $O_2\;at\;600^{\circ}C$ for 5 h, thus suggesting oxidation of $V^{4+}\;to\;V^{5+}$. When dehydrated $VO^{2+}-SAPO-5$ contacts with $D_2O$ at room temperature, the EPR signal of species A is observed. Thus species assumed as a $VO^{2+}(O_f)_2(D_2O)_3$, by considering two framework oxygens. Adsorption of deuterated ethanol, propanol on dehydrated $VO^{2+}_{-}SAPO-5$ result in another new vanadium species E and F, respectively, which are identified as a $VO^{2+}-(CH_3CH_2OD)_3,\;VO^{2+}-(CH_3CH_2CH_2OD)_2$ complex. When deuterated benzene is adsorbed on dehydrated $VO^{2+}-SAPO-5$, another new vanadium species G, identified as a $VO^{2+}-(C_6D_6)$ is observed. Possible coordination geometries of these various complexes are discussed.