Sulfur poisoning in the nickel catalyzed gasification of activated carbon in hydrogen

The effect of hydrogen sulfide on the catalytic activity of nickel has been investigated in the hydrogasification of activated carbon. The low-temperature gasification activity in the range of 400–700° C was seriously suppressed when hydrogen sulfide was added to the hydrogen stream. The carbon conversion in this temperature region was approx. 75,50,20 and 0 % for hydrogen sulfide concentration of 0,20,50 and 100 ppm. respectively. A similar deactivation was observed even in pure hydrogen if the catalyst had been previously treated with hydrogen sulfide. On the other hand, the retardation effect was much smaller in the temperature region higher than 900° C. and the original activity was easily reproduced when the catalyst was exposed to pure hydrogen. The sulfur problems in the catalytic gasification of activated carbon are discussed in connection with the gasification of coal.     

Enantiomeric composition of ipsdienol: A chemotaxonomic character for north American populations ofIps spp. in thepini subgeneric group (coleoptera: Scolytidae)

Thirty-five populations ofIps pini (Say) and one population each ofIps avulsus (Eichhoff) andIps bonanseai (Hopkins) were analyzed for the enantiomeric composition of ipsdienol (2-methyl-6-methylene-2,7-octadien-4-ol). Populations ofI. pini occur as at least two distinct regional pheromone variants: New York type [32%-(–) to 56%-(–)-ipsdienol] and California type [94%-(–) to 98%-(–)-ipsdienol]. A third phenotype may occur in southeastern British Columbia, Idaho, and Montana [91%-(–) to 95%-(–)], possibly indicating a zone of hybridization. Populations of the New York type occur in southwestern British Columbia, Alberta, Saskatchewan, Minnesota, and Wisconsin suggesting a continuum through the Canadian provinces and Lake States. The presence of the New York type in western Canada is likely linked to the Quaternary history of the transcontinentally distributed host,Pinus banksiana Lamb. MaleI. avulsus [25%-(–)] and maleI. bonanseai [–29%-(–)] both produce ipsdienol, but not ipsenol. Production of ipsdienol by maleI. pini was evaluated in six differentPinus spp. hosts. Following transfer of maleI. pini to hosts other than the host of origin, the percentage of the (–)-enantiomer of ipsdienol declined when compared to production in the host of origin.     

Amphiphilic graft copolymer latex membranes. VI. Poly(vinyl alcohol)–acrylonitrile–N-hydroxyethyl acrylamide graft copolymer latex membranes

Poly(vinyl alcohol)(PVA)–acrylonitrile(AN)–N-hydroxyethyl acrylamide (HEAAm) graft copolymer latex membranes were prepared and properties of the membranes were compared with those of PVA–AN graft latex membranes and Cuprophane PT-150. The physical constants of HEAAm were determined and the tautomerization between hydroxyethyl amide group and aminoethyl ester group upon pH changes was ascertained by infrared spectrum of poly(HEAAm) film. An increase in HEAAm content in the membrane enhanced permeabilities of solute in aqueous solutions in comparison with PVA–AN graft latex membranes, maintaining good mechanical properties in wet state. With pH variation, the permeability of the nonionic solute was unchanged, but that of the anionic solute in acidic condition was superior to that in basic condition, and the permeability of the cationic solute exhibited the opposite trend. The behavior of ionic solute were attributable to the effect of the tautomerization of the functional group in the membrane.     

Search of optimum gas mixture ratio as gas insulating medium by genetic algorithm

Genetic algorithm is applied to find the optimum gas mixture ratio as gas insulating medium substituting pure SF/sub 6/. Genetic algorithm is very useful to find the optimum solution from vast searching possibilities. Testing each gas mixture by experiment requires a long time. The present method is very efficient to preselect the candidates of gas mixtures before more thorough but time-consuming investigation via experiment is carried out. The gas mixture ratio is coded as a series of bits simulating a genetic sequence of a life form. Two-term Boltzmann equation is used to calculate the effective ionization coefficient of each gas mixture that is used to evaluate the degree of adaptation of each individual representing one set of mixture ratios. Two types of degree of adaptation are used to evaluate each individual, the effective ionization coefficient at the critical ratio of the electric field to the gas density of SF/sub 6/ of 359.3/spl times/10/sup 21/Vm/sup 2/, and the global warming potential. Based on the degree of adaptation, better individuals can be selected as parents of the next generation, leaving their genes to future generations. After some generations, the group of individuals converges into the optimum with the best degree of adaptation.     

Effect of Iron Addition on the Durability of Pd–Pt-Loaded Sulfated Zirconia for the Selective Reduction of Nitrogen Oxides by Methane

The effects of adding iron to Pd–Pt/sulfated zirconia (SZ) on the selective NO _x reduction by methane were examined based on durability tests under conditions simulating natural gas combustion exhaust. While Pd–Pt/SZ was severely deactivated at 500 °C, Pd–Pt/Fe-SZ maintained a NO _x conversion higher than 70% for over 2400 h under the same conditions. Methane conversion on Pd–Pt/Fe-SZ was significantly lower than that on Pd–Pt/SZ. XRD analysis of fresh and used catalysts showed that a part of the SZ had transformed to monoclinic ZrO₂ and that adding Fe suppressed the transformation. These results suggested that the improvement in NO _x conversion by adding Fe was due to the suppression of methane combustion and the stabilization of SZ against transformation to ZrO₂.     

Preparation of functional polymer microspheres by suspension copolymerization of diallyl phthalate with carboxylic monomers

A study was made of the suspension copolymerization of diallyl phthalate (DAP) and acrylic and methacrylic acid (AAc and MAc, respectively, which were charged after delay to the suspension of partially prepolymerized DAP) and the structure of resulting gel particles. In the copolymerization of DAP with AAc, the conversion of AAc leveled off despite an appreciable amount of AAc remaining in the aqueous phase, whereas in DAP–MAc copolymerization most MAc was polymerized in the particles. The particle structure depended significantly on the mode of comonomer charge. Earlier charge of the comonomer to the reaction system resulted in the formation of particles having comonomer unit-rich surface layer. This was interpreted in terms of phase separation through loosely crosslinked structure in the particles and supported by an adsorption test using a dye and the observation of surface structure of the particles. The timing of comonomer charge changed the amount of comonomer units in the surface layer from 0.06 to 0.60 mmole/g particle.     

Estimation of the intracrystalline diffusion coefficient of the reactant during selective catalytic reduction of nitrogen oxide by propane on Co-ZSM-5

In order to estimate the effect of diffusion during the selective catalytic reduction of nitrogen oxides (NOx) using propane on Co-ion-exchanged ZSM-5, the catalytic activity was measured for the catalysts prepared from zeolites having different crystal sizes. The conversions of NOx and propane on a catalyst having a large crystal size (1.3 μm) were much less than those on a catalyst having a smaller crystal size (0.10 μm). Based on the experimental data and certain assumptions, the effective intracrystalline diffusion coefficient of NO during the reaction in the presence of water vapor at 673 K was estimated to be (6-9)× 10^-15 m²/s. This revised version was published online in July 2006 with corrections to the Cover Date.     

Preparation of functional polymer-microspheres by suspension copolymerization of ethylene glycol dimethacrylate with hydrophilic monomers

A study was made of suspension copolymerization of ethylene glycol dimethacrylate (EDMA) with some hydrophilic monomers (M₂) to prepare gel particles having a large number and various kind of functional groups on their surface. Delayed charge of M₂ to partially prepolymerized EDMA suspension resulted in the formation of favorable particles. The polymerization leveled off despite an appreciable amount of remaining M₂ in the aqueous phase, and the amount of copolymerized M₂ and the fraction of on-surface M₂ units depended significantly on the kind of M₂ as well as the mode of M₂ charge. These dependences were explained in terms of the partition coefficient of M₂ between EDMA and water and the monomer reactivity ratio.     

Studies on synthetic polymer plates with high surface energy. III. Diethylene glycol bis(allyl carbonate)–unsaturated sulfonic acid system

Synthetic polymer plates (GPs) with high surface energy were prepared by the two-step copolymerization process previously reported, using diethylene glycol bis(allyl carbonate) (CR-39) as M₁ monomer and unsaturated sulfonates [sodium vinyl sulfonate (VS^?Na⁺), potassium styrene sulfonate (StS^?K⁺), and sodium 2-sulfoethyl methacrylate (SEM^?Na⁺)] as M₂ monomer. The contact angle (θ_H) of water for the acid-treated (immersed in an aqueous 0.1 N HCl solution for 2 h) GPs decreased in the order StS^?K⁺, VS^?Na⁺, and SEM^?Na⁺. In the case of M₂ = SEM^?Na⁺, the θ_H value was about 20°. By adding NaCl in the immersion solution and changing the pH of the immersion solution, the θ_H values for the CR-39–SEM^?Na⁺ GPs were lowered to 18.9 and 13.1°, respectively. The θ_H values for the above GPs were smaller than those for the CR-39–acrylic acid or the CR-39–methacrylic acid GPs in the previous report, whereas the contact angle (θ_Na) of water for the former after alkali treatment (immersed in an aqueous 0.1 N NaOH solution for 2h) was larger than those for the latter. The former had durability of water wettability superior to the latter because of the difference in dissociation characteristic of the respective functional group.     

APS, an adaptor protein containing PH and SH2 domains, is associated with the PDGF receptor and c-Cbl and inhibits PDGF-induced mitogenesis

Previously we cloned a novel adaptor protein, APS (adaptor molecules containing PH and SH2 domains) which was tyrosine phosphorylated in response to c-kit or B cell receptor stimulation. Here we report that APS was expressed in some human osteosarcoma cell lines, markedly so in SaOS-2 cells, and was tyrosine-phosphorylated in response to several growth factors, including platelet derived growth factor (PDGF), insulin-like growth factor (IGF), and granulocyte-macrophage colony stimulating factor (GM-CSF). Ectopic expression of the wild type APS, but not C-terminal truncated APS, in NIH3T3 fibroblasts suppressed PDGF-induced MAP kinase (Erk2) activation, c-fos and c-myc induction as well as cell proliferation. In vitro binding experiments suggest that APS bound to the beta type PDGF receptor, mainly via phosphotyrosine 1021 (pY1021). Indeed, tyrosine phosphorylation of PLC-gamma, which has been demonstrated to bind to pY1021, but not that of PI3 kinase and associated proteins, was reduced in APS transformants. PDGF induced phosphorylation of the tyrosine residue of APS close to the C-terminal end. In vitro and in vivo binding experiments indicate that the tyrosine phosphorylated C-terminal region of APS bound to c-Cbl, which has been shown to be a negative regulator of tyrosine kinases. Since coexpression of c-Cbl with wild type APS, but not C-terminal truncated APS, synergistically inhibited PDGF-induced c-fos promoter activation, c-Cbl could be a mechanism of inhibitory action of APS on PDGF receptor signaling.