Pyrolysis and gasification characterization of sewage sludge for high quality gas and char production

A study on pyrolysis, steam gasification, and carbonization-activation was conducted to produce energy and resource from waste sewage sludge. Carbonization-activation is a sequential process of pyrolysis and steam gasification. The experiment was conducted with a batch-type fixed bed reactor. A comparative analysis on the formation characteristics of products, such as gas, tar, and char, was conducted to evaluate the three cases. For sludge char, carbonization-activation showed the largest amount of porosity in the char, and its specific surface area was 80.28 m²/g with an average pore diameter of 6.229 nm. The best adsorption ability of benzene, a light tar, was 175 mg/g. For the producer gas, steam gasification obtained the largest amount of 20.1 L. Similarly, carbonization-activation showed a large value of 16.6 L. Hydrogen and carbon monoxide concentrations were higher in the producer gas due to steam reforming compared with carbonization-activation. Energy yields were 209 kJ and 226 kJ for steam gasification and carbonization-activation, respectively. The amount of tar formation did not show a significant difference, but the largest one was found in steam gasification. The gravimetric tar amount for steam gasification was 23.5 g/Nm³. However, the selected light tar displayed the lowest concentration for the carbonization-activation. Such concentrations were 2.79 g/Nm³, 0.75 g/Nm³, 0.14 g/Nm³, and 0.14 g/Nm³ for benzene, naphthalene, anthracene, and pyrene, respectively. Therefore, carbonization-activation was found to be the most effective process for producing high quality sludge char and producer gas for utilizing waste sludge into renewable energy and resources.     

Voltammetric Study of Silver in a Glass Melt

The redox reaction and the oxidation state of silver in a glass melt were studied by cyclic voltammetry and chronopotentiometry between 800° and 1200°C. Silver ions in glass were reduced at a less noble potential than the rest potential of a platinum electrode. A reversible redox reaction of silver in glass was indicated from the analysis of the cyclic voltammogram. An analysis based on the electron transference number revealed that the solubility of reduced silver increased with increasing temperature. Ag⁺/Ag⁰ equilibrium in glass was suggested because the rest potential of the platinum electrode in glass was a mixed potential. No relation was observed between the redox behavior of silver in glass and optical basicity. O-type redox behavior of silver in glass was shown.     

On-Board Optical Data Communications Network for Train Control

Recently, electronic control equipment has begun to be installed in trains. This equipment is being used to communicate control and status information to allow trains to be operated more efficiently and reliably. However, the use of such equipment causes an increase in the amount of control and monitor information generated on a train, which in turn causes an increase in the amount of wiring required to carry the information. Until now, monitor equipment data have been multiplexed, and metal wire cables have been used, to reduce the amount and weight of wiring used [1].     

Oxidative coupling of methane over some titanates based perovskite oxides

A series of perovskites of the formula Ca_1–xSr_xTi_1–yM_yO_3– (M = Fe or Co,x = 0–1,y = 0–0.6 for Fe,y = 0–0.5 for Co) were prepared and tested as the catalyst for the oxidative coupling of methane. The catalysts were stable under the reaction conditions. The catalysts of high p-type and oxide ionic conductivity afforded the high selectivity. Some catalysts containing Co on B-sites are thermally unstable and decomposed to metal oxide components at high temperature, giving rise to synthesis gas production.     

Selective catalytic reduction of NOx with propylene in the presence of oxygen over Co–Pt promoted H-MFI and HY

Kinetic and in situ spectroscopic studies of Co–Pt/MFI and Co–Pt/HY catalysts for the selective reduction of NO_x with propylene in the presence of oxygen were carried out. The results of catalytic tests of Co–Pt/MFI showed that the addition of Pt to Co based catalyst improved the activity, but a small increase in selectivity to N₂O (15–20%) was observed. In the case of Co–Pt/HY catalyst, the addition of Pt improved the activity more significantly and however, a larger increase in selectivity to N₂O (6–72%) was obtained. It was also found from the results of FT-IR studies of Co–Pt/MFI that the reduction of NO to N₂ was as follows: firstly the oxidation of NO to NO₂ occurred over metallic Pt and NO₂ forms Co–NO₂, Co–ONO, and/or Co–ONO₂; secondly, the partial oxidation of C₃H₆ was happened over Brønsted acid sites and the reaction of NO₂ formed on Co sites with partial oxidized C₃H₆ produced organo-nitro species. These species were dehydrated and isomerized to form isocyanate. Finally, [NCO] type intermediates react with NO from gas phase to selectively yield N₂.     

Modification of poly(vinyl chloride). XXXIII. Novel poly(vinyl chloride) foam crosslinked with 6-dibutylamino-1,3,5-triazine-2,4-dithiol

The formulation for producing the PVC foam crosslinked with a novel crosslinking agent such as 6-dibutylamino-1,3,5-triazine-2,4-dithiol (DB) was studied to determine the processing conditions. DB was almost consumed by radical combination with a coexistent blowing agent such as azobisformamide to give a high-density foam with excessively low crosslinking density. Blowing agents such as p-toluenesulfonylhydrazide (TSH) and 4,4′-oxybis(benzenesulfonylhydrazide) (OBSH) gave a crosslinked foam of low density, while a combination of the two crosslinking agents had moderate crosslinking reaction rate. The formulation recommended in the present study consists of PVC Zeon 101EP or Zeon 121 for paste, 100 parts; DOP, 100 parts; DB, 3–5 parts; OBSH or TSH, 10 parts; MgO, 1–3 parts; and RP101 (mixture of Ba, Ca, and Zn stearate), 2 parts, which gave colorless and insoluble foam of apparent density 0.14 under hot pressing at 180°C. The molded foam could be released without extraction of heat from a hot mold for fusion and expansion.     

Development of polymer‐molding‐releasing metal mold surfaces with perfluorinated‐group‐containing polymer plating

The polymer‐molding‐releasing properties of metal molds were found to be related to the following factors: (1) interfacial chemical bonding between the surfaces of polymers and metal molds and (2) a friction force or friction coefficient between polar substances and/or low‐molecular‐weight components in the polymers and physical factors on mold surfaces. We theoretically and experimentally confirmed that metal molds with good polymer‐molding‐releasing properties had very small surface free energies. We also proved that the surface free energies in the resulting polymer moldings were lower than before shaping. The molding releasing properties improved with decreasing friction force and friction coefficient between the surface of polymers and metal molds and with decreasing surface free energy. To obtain metal molds with lower surface free energies, we developed a polymer plating method with perfluorinated‐group‐containing triazine dithiol. The Metal mold treated by polymer plating had lower critical surface tension (7.5 mJ/m²) than Teflon (18 mJ/m²), indicating that the surface consisted of CF₃ ? groups. The treated mold showed excellent durability in its releasing properties, which was better than that of the untreated mold. This technique was developed for the production of molds for the Fθ lens and the naturally bright focusing screen. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2549–2556, 2003     

Synthesis and surface-active properties of trimeric-type anionic surfactants derived from tris(2-aminoethyl)amine

Trimeric-type anionic surfactants (3C_ntaAm, where n is a hydrocarbon chain length of 8, 10, or 12) with three hydrocarbon chains and three carboxylate headgroups were synthesized from tris(2-aminoethyl)amine, and their properties were investigated by surface tension, electrical conductivity, dynamic and static light-scattering, fluorescence of pyrene, and emulsification power techniques. The critical micelle concentrations (CMC) of 3C_ntaAm were 0.00092–0.00834 mmol dm⁻³, and the surface tensions at the CMC were 33.3–39.9 mN m⁻¹. The areas per molecule occupied by 3C₁₀taAm and 3C₁₂taAm were extremely small, showing they were highly compact at the air/water interface. In addition, adsorption or micellization behavior of 3C_ntaAm was estimated by parameters such as pC ₂₀ (the efficiency of surface adsorption), CMC/C ₂₀ (the ease of adsorption relative to the ease of micellization), and ΔG _M ^o (Gibbs energy of micellization). Dynamic and static light-scattering mesurements of 3C_ntaAm showed a hydrodynamic radius of 45–61 nm above the CMC and aggregation numbers of 10–82 at the CMC, respectively. The fluorescence intensity ratio of the first to the third band in the emission spectra of pyrene started to lower from far above the CMC for 3C₈taAm and 3C₁₀taAm, and below the CMC for 3C₁₂taAm. This suggests that loose micelles or premicellar aggregates are formed in solutions. Mixtures of aqueous solutions of 3C_ntaAm and toluene formed oil-in-water-type emulsions, and the stabilizing abilities were in the order of 3C₈taAm>3C₁₀taAm>3C₁₂taAm. The degree of emulsification of 3C₈taAm remained at 69% after 24 h of standing. Thus, 3C_ntaAm exhibited unique properties superior to monomeric or dimeric surfactants that were significantly influenced by their hydrocarbon chain lengths.