Regeneration process and adsorbent performance were investigated by a fixed-bed adsorber at 300 • C. Surface species, zeolite structure, and Pt morphology were characterized by FT-IR, XRPD and EXAFS, respectively. Performance test results indicated that ethanol adsorption capacity of Pt/NaY-SiO 2 is about 2.5 times that of NaY-SiO 2 . After regeneration, adsorption-capacity loss is 2.5 and 43%, respectively, for Pt/NaY-SiO 2 regenerated at superficial velocity of 13.2 (PtR (HF) ) and 5.3 cm/min (PtR (LF) ); in contrast, it is 8 and 21%, respectively, for NaYR (HF) and NaYR (LF) . The appearance of absorption bands in the CH stretching region (υ CH ) of the IR spectra characterizing the regenerated NaY-SiO 2 suggested that the adsorption-capacity loss for NaY-SiO 2 was mainly caused by the deposition of carbonaceous species formed in regeneration, which cannot be burned off readily at 300 • C. In contrast, no υ CH bands have been observed for the IR spectra of PtR (HF) and PtR (LF) , indicating that Pt helps to burn off carbonaceous species. However, Pt agglomeration was observed in TEM and EXAFS for Pt/NaY-SiO 2(LF) . The appearance of a υ CO band at about 2085 cm −1 of the IR spectra characterizing PtR (LF) suggested that Pt agglomeration was induced by CO adsorption. The growth of Pt particles decreases the ethanol adsorbed on Pt together with the conversion of ethanol to ethoxides and aldehyde, leading to a decrease of adsorption capacity.
Anionic polymerization technique has been utilized to synthesize a bilaterally sulfur‐functionalized polystyrene, SCH3‐polystyrene‐SH. The synthesis scheme consists of (1) initiation of 4‐vinylbenzylmethyl sulfide with sec‐butyllithium to form a living sulfur‐containing initiator, (2) polymerization of styrene, and (3) termination of growing polystyrene chain with ethylene sulfide. The resulting bilaterally sulfur‐functionalized polystyrene is used to make polystyrene/gold nanoparticles (AuNPs) nanocomposite with AuNPs formed in situ in polymer solution through reduction of AuClO4. The effects of the polymer/Au molar ratio as well as the molecular weight of polymer on the size and dispersion of formed AuNPs have been studied, and the superiority of bilaterally functionalized polymer to unilaterally functionalized polymer has been demonstrated. The polystyrene/AuNPs composite has been characterized by GPC, 1H‐NMR, 13C‐NMR, EDS, TEM, UV‐Vis, and DSC. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1268–1277
The coupling agent propyl] tetrasulfide) was modified by substituting polyisoprenyl (PI) carbanions for the ethoxyl groups on silicon for increasing the interaction of rubber with its fillers. The modification was carried out by the reaction of TESPT with polyisoprenyllithium, which had been previously prepared by anionic polymerization of isoprene using butyllithium. The success of the substitution was confirmed by Fourier-transform infrared spectroscopy, and the molecular weight of the modified TESPT (PI-TESPT) was determined from gel permeation chromatography measurements. The effects of tethered PI, as well as of its chain length, on the mechanical and dynamic properties of rubber compounds were examined using a universal testing machine and dynamic mechanical analysis (DMA). In rubber sample preparation, the amount of PI 3 -TESPT (PI of 2900 g/mol) used in rubber compounding is equal to that of the reference sample with TESPT (S TESPT ). For S PI-TESPT samples, the amounts of PI 6 -TESPT (PI of 5500 g/mol) and PI 14 -TESPT (PI of 13,700 g/mol) used were calculated as molar ethoxyl groups which are nearly equivalent to those of PI 3 -TESPT. At the same wt % (parts per hundred, phr) of elemental sulfur in rubber compounds, despite the order of cross-
A novel conjugated block copolymer, poly(9,9-dioctylfluorene)-block-poly(3-hexylthiophene) (PFBPT) and its nanocomposite containing graphene sheets were synthesized for enhancing optoelectronic performance. Graphene sheets were in-situ formed in the polymer matrix via a reduction of octadecylamine-functionalized graphite oxide, where the graphite oxide came from acidification and exfoliation of graphite. The blue-green light-emitting poly(9,9-dioctylfluorene) block and red-orange light-emitting poly(3-hexylthiophene) block exhibit a combined white electroluminescence when the composite materials were fabricated as the emitting layer of a polymeric light-emitting diode (PLED). Graphene does not alter the optical characteristics wavelength of PFBPT but electric conductivity increases with the amount of graphene. The HOMO and LUMO were measured and the band gap is smaller with existence of graphene. The threshold voltage decreases with an increase in the graphene content. The device fabricated with PFBPT/graphene nanocomposite containing 1% graphene has a maximum white-light luminescence at a voltage of 9.0 V.
To help elucidate the oxychlorination redispersion reaction mechanism, the surface species formed on the surface of -Al2O3 was characterized by X-ray absorption spectroscopy (XAS). The efficacy of redispersion was assessed by the Pt–Pt coordination number (CNPt–Pt) of redispersed, and then reduced samples. A nearly fully redispersed complex (Ptrd52) was prepared by treating a sintered model Pt/-Al2O3 catalyst at 520 °C, Air/EDC (ethylene dichloride) of 30, and WHSV (Weight Hourly Space Velocity) of 0.07 h−1 for 16 h. For investigating temperature effects, samples treated at 460 (Ptrd46) and 560 C (Ptrd56) were also prepared for comparison. It was found that, while an octahedral resembling Pt(Os)3–4(O–Cl)2–3 (Os represents support oxygen or hydroxyl oxygen) complex was formed on -Al2O3 of Ptrd52, less O–Cl ligands were formed on the redispersed complexes, Ptrd46 and Ptrd56. A negative correlation of CNPt–Pt with CNPt–Cl* (Cl* represents the Cl atom in O–Cl ligand) for these three samples further suggested that the formation of Pt–O–Cl played a key role in the redispersion process. Pt–O–Cl could be formed in the reaction of reactive Cl and PtO2. At an operation temperature of lower-than-optimal temperatures of 520 C, less Cl2 dissociation and less O–Cl ligands were formed. On the other hand, higher temperatures may facilitate Cl2 dissociation, but reduce the equilibrium conversion of HCl to Cl2, leading to increased HCl reaction with Pt (PtO2) clusters to form Pt–Cl (Cl is the atom bonded directly to Pt), and decreased formation of Pt–O–Cl.
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