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排序方式: 共有117条查询结果,搜索用时 15 毫秒
1.
2.
Towards an Environmentally Acceptable Heterogeneous Catalytic Method of Producing Adipic Acid by the Oxidation of Hydrocarbons in Air 总被引:1,自引:0,他引:1
Raja Robert Lee Sang-Ok Sanchez-Sanchez Manuel Sankar Gopinathan Harris Kenneth D.M. Johnson Brian F.G. Thomas John Meurig 《Topics in Catalysis》2002,20(1-4):85-88
A survey is given of the catalytic methods potentially available for the production of adipic acid by the oxidation of readily available hydrocarbon precursors under environmentally benign conditions. Encouraging results are reported using H2O2 as oxidant and microporous FeAlPO-5 as catalyst at moderate temperatures. 相似文献
3.
NMR imaging of low pressure,gas‐phase transport in packed beds using hyperpolarized xenon‐129
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Galina Pavlovskaya Joseph Six Thomas Meersman Navin Gopinathan Sean P. Rigby 《American Institute of Chemical Engineers》2015,61(11):4013-4019
Gas‐phase magnetic resonance imaging (MRI) has been used to investigate heterogeneity in mass transport in a packed bed of commercial, alumina, catalyst supports. Hyperpolarized 129Xe MRI enables study of transient diffusion for microscopic porous systems using xenon chemical shift to selectively image gas within the pores, and, thence, permits study of low‐density, gas‐phase mass‐transport, such that diffusion can be studied in the Knudsen regime, and not just the molecular regime, which is the limitation with other current techniques. Knudsen‐regime diffusion is common in many industrial, catalytic processes. Significantly, larger spatial variability in mass transport rates across the packed bed was found compared to techniques using only molecular diffusion. It has thus been found that that these heterogeneities arise over length‐scales much larger than ~100 µm. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4013–4019, 2015 相似文献
4.
Preparation,characterization, electrical and antibacterial properties of sericin/poly(vinyl alcohol)/poly(vinyl pyrrolidone) composites
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In this study, we focused on the fabrication of poly(vinyl alcohol) (PVA)/poly(vinyl pyrrolidone) (PVP)/sericin composites via a simple solution‐blending method. The composites were characterized by Fourier transform infrared (FTIR) spectroscopy, UV spectroscopy, X‐ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry, thermogravimetric analysis (TGA), and measurements of the conductivity, tensile strength, and antibacterial activity against Staphylococcus aureus. The results of FTIR and UV spectroscopy implied the occurrence of hydrogen bonding between sericin and the PVA/PVP blend. The structure and morphology, studied by XRD and SEM, revealed that the sericin particles were well dispersed and arranged in an orderly fashion in the blend. The glass‐transition temperature (Tg) of the composite was higher than that of the pure blend, and the Tg value shifted toward higher temperatures when the volume fraction of sericin increased. TGA indicated that sericin retarded the thermal degradation; this depended on the filler concentration. The mechanical and electrical properties, such as the tensile strength, alternating‐current electrical conductivity, dielectric constant, and dielectric loss of the composites, were higher than those of the pure blend, and these properties were enhanced when the concentration of sericin was increased up to 10 wt % filler content, whereas the elongation at break of the composite decreased with the addition of sericin particles. The antibacterial properties of the composite showed that sericin had a significant inhibitory effect against S. aureus. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43535. 相似文献
5.
Morphology‐dependent electrocatalytic activity of nanostructured Pt/C particles from hybrid aerosol–colloid process
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Ratna Balgis Aditya F. Arif Takahiro Mori Takashi Ogi Kikuo Okuyama Gopinathan M. Anilkumar 《American Institute of Chemical Engineers》2016,62(2):440-450
An optimum nanostructure and pore size of catalyst supports is very important in achieving high catalytic performances. In this instance, we evaluated the effects of various carbon nanostructures on the catalytic performances of carbon‐supported platinum (Pt/C) electrocatalysts experimentally and numerically. The Pt/C catalysts were prepared using a hybrid method involving the preparation of dense, hollow, and porous nanostructured carbon particle via aerosol spray pyrolysis followed by microwave‐assisted Pt deposition. Electrochemical characterization of the catalysts showed that the porous Pt/C catalyst gave the best performance; its electrochemical surface area was much higher, more than twice than those of hollow or dense Pt/C. The effects of pore size on electrocatalysis were also studied. The results showed the importance of a balance between mesopores and macropores for effective catalysis with a high charge transfer rate. A fluid flow model showed that good oxygen transport contributed to the catalytic activity. © 2015 American Institute of Chemical Engineers AIChE J, 62: 440–450, 2016 相似文献
6.
Here we demonstrate the power of in situ scattering techniques in the understanding of formation of nanoporous aluminosilicate and aluminophosphate materials. We utilised a number of X-ray techniques, in particular, in situ energy dispersive X-ray diffraction (EDXRD) and small angle and wide angle X-ray scattering (SAXS/WAXS) techniques for this purpose. The in situ SAXS measurements show the formation of homogeneous precursors in the size of ca. 10 nm, prior to the crystallization of LTA. The crystal size is estimated by fitting the SAXS patterns with an equation for a cubic particle, and it is revealed that the final crystal size of the LTA depends on the synthesis temperature. Whereas, the crystallisation of CoAlPO-5, occurs through the formation of poly-dispersed particles with an average size of the precursor particle of ca. 50 nm. Also shown the effect of temperature and structure directing organic cations on the production of CoAlPO-5 materials. 相似文献
7.
Hong K. D. Nguyen Gopinathan Sankar Richard A. Catlow 《Journal of Porous Materials》2017,24(3):567-572
This study focuses on the effect of the synthetic conditions on the stability, particle size, redox chemistry of cobalt into the framework of CoAlPO-34. It seems that the most sufficient pH for the substitution of Co into the framework of CoAlPO-34 was pH around 7.5 when the as-synthesized bifunctional catalyst has the best redox property. The pH of the initial gel has strong effect on the particle size of CoAlPO-34. The substitution of cobalt and redox chemistry were determined by: EXAFS combined with XRD, XANES, IR. Stability of the nanoporous catalyst studied by in situ XRD were also reported. 相似文献
8.
9.
Carbon fibre reinforced Al-12% Si alloy composite has been fabricated by pre-treating the fibres with K2ZrF6 followed by molten alloy infiltration and subsequent hot pressing of the preforms. The infiltration conditions were arrived
at based on the measurement of tensile strength of the fibres extracted from the preforms. The fibre volume per cent of 20
was found to result in composite tensile strength of about 240 MPa as compared to tensile strength of 100 MPa for the unreinforced
matrix. Characterization of the interface revealed the formation of ZrSi2 and diffusion of potassium and aluminium into the fibre. The interfacial bonding was strong as is evinced by the absence
of fibre pull-out on to the fracture surface. 相似文献
10.
E. Gopinathan S. C. Dutta Roy R. K. Patney 《Circuits, Systems, and Signal Processing》1987,6(1):95-106
A single-parameter controlled-variable amplitude change function has been constructed for digital filtering using multiple units of a prototype filter. The limits of variation are discussed. The technique is shown to be useful not only for the reduction of errors in either the pass band or the stop band of the overall filter, but also for varying the cutoff frequency of the overall filter over a wide range. Hardware implementation problems resulting from a wide variation are shown to be overcome by a modular approach. 相似文献