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Lambda dynamics sampling

Catalysts were characterized by means of X-ray diffraction (Phillips diffractometer PW3710, with CuKa as radiation source), UV-Vis-DR spectroscopy (Perkin-Elmer Lambda 19) and chemical analysis. Measurements of surface acidity were carried out by recording transmission FT-IR spectra of samples pressed into self-supported disks, after adsorption of pyridine at room temperature, followed by stepwise desorption under dynamic vacuum at increasing temperature (Perkin-Elmer mod 1700 instrument). The procedure for chemical analysis is described in detail in ref. (13). [Pg.117]

Figure 67. Influence of the washcoat formulation on the conversion of CO, HC and NO , reached over various engine aged three-way catalysts as a function of the exhaust gas lambda value (monolith catalyst with 62cells cm three-way formulation with Pt 1.16gC, Rh 0.23gl" engine bench test A/F scan at a space velocity of 60000 Nl 1 h exhaust gas temperature 723 K dynamic frequency 1 Hz amplitude 1 A/F engine bench high temperature aging cycle for lOOh). Sample A baseline formulation, samples B-D increasing amounts of stabilizers. Figure 67. Influence of the washcoat formulation on the conversion of CO, HC and NO , reached over various engine aged three-way catalysts as a function of the exhaust gas lambda value (monolith catalyst with 62cells cm three-way formulation with Pt 1.16gC, Rh 0.23gl" engine bench test A/F scan at a space velocity of 60000 Nl 1 h exhaust gas temperature 723 K dynamic frequency 1 Hz amplitude 1 A/F engine bench high temperature aging cycle for lOOh). Sample A baseline formulation, samples B-D increasing amounts of stabilizers.
A KrF excimer laser (Lambda Physik LEXTRA 200, 248 nm, 30 ns fwhm) or a XeF excimer laser (ibid., 351 nm, 30 ns fwhm) was used as an excitation pulse for inducing expansion/contraction dynamics. The fluence was adjusted with partially transmitting laser mirrors, and was monitored shot-by-shot by a photodiode whose output was corrected with a joulemeter (Gentec, ED-200) with an oscilloscope (Hewlett-Packard, HP54522A). A c tral area of the excimer laser pattern with a homogeneous intensity distribution was chosen with an appropriate aperture and then focused onto the sample surface by using a quartz lens (f = 200 mm). Fresh surface of the sample film was used in every measurement. Etch depth was measured by a surface depth profiler (Sloan, Dektak 3). All experiments were done in air at room temperature. [Pg.214]

UV-VIS extinction spectra were measitred with a Lambda 35 spectrophotometer (Perkin Elmer, USA). Particle size distribution, based on hydrodynamic diameter, was evaluated by Nano S (Malvern, UK), a dynamic light scattering analyzer (DLS). Urueacted metal cations, extracted from the sample by a semi-permeable osmotic membrane (Visking tube), were detected by ICP-AES qirantitative analysis (Liberty 200, Varian, Austraha) in order to determine the reaction yield. Suspensiorts were dropped and dried on a copper grid, then observed by high resolution transmission electron microscopy (HRTEM) (Tecnai F20) and by the STEM mode with microanalysis EDX. [Pg.622]


See other pages where Lambda dynamics sampling is mentioned: [Pg.604]    [Pg.43]    [Pg.588]    [Pg.601]    [Pg.120]    [Pg.52]    [Pg.585]    [Pg.101]    [Pg.956]   
See also in sourсe #XX -- [ Pg.205 ]




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