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991.
Manfred Nacken Lina Ma Steffen Heidenreich Gino V. Baron 《Applied catalysis. B, Environmental》2009,88(3-4):292-298
Silicon carbide-based filter elements were catalytically activated to provide filter elements for catalytic tar removal from biomass-derived syngas. The filter element support was coated with CeO2, CaO–Al2O3 and MgO with a specific surface of 7.4, 15.9 and 21.9 m2/g synthesized by exo-templating with activated carbon. Doping of a MgO coated filter element with 60 wt% NiO has led to an increase of the specific surface from 0.15 to 0.21 m2/g, whereas in case of a MgO–Al2O3 coated filter element a decrease from 1.18 to 0.91 m2/g was found. An increase of the NiO loading from 6 to 60 wt% on a MgO coated filter element resulted in an increase of the naphthalene conversion from 91 to 100% at 800 °C and a face velocity of 2.5 cm/s at a naphthalene concentration of 5 g/Nm3 in model biomass gasification gas. In case of a MgO–Al2O3 coated filter element with 60 wt% NiO in addition to complete naphthalene conversion in the absence of H2S, a higher conversion of 66% was found in the presence of 100 ppmv H2S compared to 49% of the MgO–NiO coated filter element. After scaling up of the catalytic activation procedure to a 1520 mm long filter candle, which shows an acceptable differential pressure of 54.9 mbar, 58 and 97% naphthalene conversion was achieved in the presence and absence of H2S, respectively. The calculated WHSV value of 209.6 Nm3 h−1 kg−1 indicates the technical feasibility of a further increase of the catalytic performance by an increase of the NiO loading. 相似文献
992.
993.
通过SEM观察和EBSD技术研究了冷轧中碳Cr-Mo钢在600 ℃退火不同时间后的组织演变规律。结果表明,随退火时间的延长,渗碳体颗粒分布越弥散,并且球化越来越明显,变形后的铁素体条带转变为铁素体等轴晶粒。晶粒内部渗碳体颗粒较小,晶界处渗碳体颗粒较大,部分呈连续分布,且晶粒尺寸不断增大,但在退火时间小于240 min时,晶粒长大不明显,进一步延长保温时间后,晶粒尺寸增长变快。当保温时间从15 min延长到120 min和480 min时,铁素体平均晶粒尺寸从0.670 μm长大到0.732 μm和2.000 μm。在退火0~120、120~240、240~360和360~480 min时段的晶粒长大速率分别为55.7%、9.7%、74.3%和42.9%,其中0~15 min时晶粒尺寸的增长比例高达42.6%。在退火0~120 min时段,晶粒长大速率相对较大,从节约能源的角度考虑,退火时间可以定在120 min。 相似文献
994.
Francesca Blasi Lina Cossignani Ancilla Bosi Silvia Maurelli Gilda D’Arco Dennis Fiorini Maria Stella Simonetti Pietro Damiani 《Journal of the American Oil Chemists' Society》2008,85(7):613-619
The present research deals with the chemical esterification of the sn-2- position of sn-1,3-diacylglycerol (sn-1,3-DAG) with 9cis,11trans (c9,t11) and 10trans,12cis (t10,c12) conjugated linoleic acid (CLA) isomers to obtain structured triacylglycerols (TAG); the sn-1,3-DAG substrates were produced from extra virgin olive oil by means of enzymatic reactions while CLA isomers were obtained
using a three-step procedure based on alkaline hydrolysis of sunflower oil, urea purification of linoleic acid (LA) and alkaline
isomerization of LA. The results showed good levels of CLA incorporation in structured TAG at the tested temperatures: 37.5%
at 4 °C and 39.1% at 14 °C. To evaluate the incorporation of CLA isomers in sn-2- position of sn-1,3-DAG structural analysis of the newly synthesized TAG was carried out using an enzymatic and a chemical method. The results
of the structural analysis also showed up the occurrence of acyl migration. The pancreatic lipase method allowed the direct
determination of the fatty acid composition of TAG sn-2- position but this enzymatic method showed different results (p < 0.05) in respect to the chemical one; this occurrence could be due to an acylic specificity of the lipase. High incorporation
of CLA isomers in sn-2- position of TAG was observed, 77.0% at 4 °C and 81.5% at 14 °C, considering the results of the chemical procedure. 相似文献
995.
Lijun Du Wei Li Lina Fan Binbo Jiang Jingdai Wang Yongrong Yang Zuwei Liao 《应用聚合物科学杂志》2010,118(3):1743-1751
Hybrid titanium catalysts supported on silica/poly(styrene‐co‐acrylic acid) (SiO2/PSA) core‐shell carrier were prepared and studied. The resulting catalysts were characterized by Fourier transform infrared (FTIR) spectroscopy, laser scattering particle analyzer and scanning electronic microscope (SEM). The hybrid catalyst (TiCl3/MgCl2/THF/SiO2·TiCl4/MgCl2/PSA) showed core‐shell structure and the thickness of the PSA layer in the two different hybrid catalysts was 2.0 μm and 5.0 μm, respectively. The activities of the hybrid catalysts were comparable to the conventional titanium‐based Ziegler‐Natta catalyst (TiCl3/MgCl2/THF/SiO2). The hybrid catalysts showed lower initial polymerization rate and longer polymerization life time compared with TiCl3/MgCl2/THF/SiO2. The activities of the hybrid catalysts were enhanced firstly and then decreased with increasing P/P. Higher molecular weight and broader molecular weight distribution (MWD) of polyethylene produced by the core‐shell hybrid catalysts were obtained. Particularly, the hybrid catalyst with a PSA layer of 5.0 μm obtained the longest polymerization life time with the highest activity (2071 kg PE mol?1 Ti h?1) and the resulting polyethylene had the broadest MWD (polydispersity index = 11.5) under our experimental conditions. The morphology of the polyethylene particles produced by the hybrid catalysts was spherical, but with irregular subparticles due to the influence of PSA layer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
996.
Jean-Marc Schweitzer Clementina López-García Daniel Ferré 《Chemical engineering science》2010,65(1):313-321
Safety is a high-priority topic for the chemical industry to minimize the frequency and severity of accidents while keeping the productivity and quality of the production. The processes that may undergo thermal runaways due to exothermic reactions are at the heart of the risks of accidents. The study of such highly reactive systems is essential to achieve a safe and productive operation of existing processes and to ensure inherently safe new designs. It is well known that the stationary analysis with the van Heerden criterion must be satisfied, however, this is not sufficient to ensure reactor stability. Only dynamic analysis can provide an accurate answer concerning the safe operation of the reactor. Most of the reported stability studies are carried out for relatively simple systems (pseudo-homogeneous models, simple reaction schemes). This work presents the dynamic thermal stability study of a refining process (hydrotreatment of light cycle oils) carried out with real gasoils at industrial operating conditions. A 1D dynamic model that accurately represents the reactive system (gas–liquid–solid) was developed and validated with experimental pilot plant data. This mathematical model was used to perform the thermal stability analysis of the dynamic system using a perturbation method. The effect of the variation of the heat transfer coefficient on the thermal stability is presented. The spectral analysis of the eigenvalues indicating the stable/unstable behavior of the reactive system was compared with dynamic simulations. An excellent agreement was found between the simulations and the stability analysis. The case of oscillating behavior is also described. The frequencies of oscillation determined by the stability analysis are compared to the frequencies calculated by Fourier transform applied to the simulated signal. The reactor behavior and the oscillations features are accurately predicted with this stability analysis method. 相似文献
997.
Strong honeycomb like nanocomposite sponges were fabricated from starch and PVA by using repeated cycles of freezing and thawing and reinforcing with cellulose whiskers. Their structure and properties were investigated with WAXD, FT‐IR, SEM, DMTA, rheological measurements, and LSCM. The results revealed that the repeated freezing/thawing cycles induced a physically crosslinked chain packing between starch and PVA, as well as a phase separation caused by the crystalline ice and syneresis. Thus, larger pores and tougher walls emerged in the sponges, leading to a high swelling degree. The sponges reinforced with cellulose whiskers exhibited improved dimensional stability and enhanced strength. These nanocomposite sponges are promising for wound dressing and tissue engineering applications.
998.
Hydrophobic materials were successfully prepared from SPI and NR by blending via freezing/lyophilizing. The interfacial interaction, surface properties, hydrophobicity, and mechanical properties, biodegradability as well as the biocompatibility were investigated. The blend sheets exhibited good interface adhesion and good optical transparency. Their hydrophobicity was significantly improved compared with pure soy protein sheets. XPS results proved the NR surface enrichment. Flexibility and toughness of the blend sheets were enhanced and phase inversion phenomena were observed. Furthermore, the blend sheets exhibited good biodegradability and biocompatibility capable of supporting cell adhesion and proliferation.
999.
Emmanuelle‐Anita‐Claude Demengeot Inga Baliutaviciene Jolita Ostrauskaite Liudvikas Augulis Violeta Grazuleviciene Lina Rageliene Juozas Vidas Grazulevicius 《应用聚合物科学杂志》2010,115(4):2028-2038
The different natural oils epoxidized with 3‐chloroperbenzoic acid were crosslinked with diepoxy reactive diluents, bisphenol A propoxylate diglycidyl ether, and 3,4‐epoxycyclohexylmethyl‐3,4‐epoxyclohexane‐carboxylate, using cationic initiator at 60°C and photoinitiators at the room temperature. The insoluble fraction of the polymeric products was 59–90%. The Young modulus of the crosslinked polymer films ranged from 2 to 861 MPa. The 10% weight loss temperatures of the crosslinked polymers estimated by thermogravimetric analysis were in the range from 250 to 420°C. The water vapor transmission rate of the crosslinked biopolymer films ranged from 6 to 49 g/m2/24 h. Biochemical oxygen demand and biodegradation in soil of the crosslinked polymers were studied. The crosslinked polymers showed higher biodegradation rate than cellulose, starch, and polyvinylalcohol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
1000.
A Schiff-based fluorescence probe benzene-1,2-dicarbaldehyde bis-benzoyl hydrazide (L) was designed and synthesized. Its sensing behavior toward metal ions has been investigated by absorption and fluorescence spectroscopy. Indicator L showed high selectivity to Zn2+ in various solvents, whereas other metal ions failed to induce response. Especially Cd2+, which has similar chemical properties with Zn2+, can be distinguished from Zn2+ obviously. 相似文献