Thermal deactivation of Pt/Rh commercial automotive catalysts

The immobilization and stabilization of Aspergillus oryzae ?-galactosidase on Duolite??A568 was achieved using a combination of physical adsorption, incubation step in buffer at pH 9.0 and cross-linking with glutaraldehyde and in this sequence promoted a 44% increase in enzymatic activity as compared with the biocatalyst obtained after a two-step immobilization process (adsorption and cross-linking). The stability of the biocatalyst obtained by three-step immobilization process (adsorption, incubation in buffer at pH 9.0 and cross-linking) was higher than that obtained by two-steps (adsorption and cross-linking) and for free enzyme in relation to pH, storage and reusability. The immobilized biocatalyst was characterized with respect to thermal stability in the range 55-65 ?C. The kinetics of thermal deactivation was well described by the first-order model, which resulted in the immobilized biocatalyst activation energy of thermal deactivation of 71.03 kcal/mol and 5.48 h half-life at 55.0 ?C.

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Dynamic behavior of automotive catalysts

Journal of Catalysis ◽

10.1016/0021-9517(85)90092-2 ◽

1985 ◽

Vol 94 (1) ◽

pp. 166-174 ◽

Cited By ~ 62

Author(s):

Richard K. Herz ◽

Jeffrey A. Sell

Keyword(s):

Dynamic Behavior ◽

Automotive Catalysts

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An X-ray absorption spectroscopic investigation of aged automotive catalysts

Catalysis and Automotive Pollution Control III, Proceedings of the Third International Symposium CAPoC 3 - Studies in Surface Science and Catalysis ◽

10.1016/s0167-2991(06)81472-2 ◽

1995 ◽

pp. 749-762 ◽

Cited By ~ 9

Author(s):

F. Maire ◽

M. Capelle ◽

G. Meunier ◽

J.F. Beziau ◽

D. Bazin ◽

...

Keyword(s):

Spectroscopic Investigation ◽

Automotive Catalysts ◽

X Ray ◽

X Ray Absorption

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Carbon Filament Growth on Fully Formulated Pd/Rh Automotive Catalysts

Microscopy and Microanalysis ◽

10.1017/s1431927600032827 ◽

2000 ◽

Vol 6 (S2) ◽

pp. 66-67

Author(s):

J.W. Hangas ◽

G.W. Graham ◽

R.W. McCabe ◽

W. Chun

Keyword(s):

Carbon Monoxide ◽

Catalytic Activity ◽

Operating Conditions ◽

The Other ◽

Carbon Filament ◽

Automotive Catalysts ◽

Exhaust Catalysts ◽

Stabilization Procedure ◽

Carbon Filaments ◽

Aged Catalyst

Automotive exhaust catalysts are typically operated under stoichiometric conditions to minimize nitrogen oxide, hydrocarbon, and carbon monoxide pollutants. These catalysts do not form carbon filaments under normal operating conditions. In development of catalysts, however, a stabilization procedure is sometimes utilized on used catalysts (dynamometer or vehicle) to purge the catalyst of sulfur prior to measuring the catalytic activity in sweep and light-off testing. The stabilization procedure consists of running the catalyst under rich (excess fuel) conditions for 0.5hr. This study documents the existence of carbon filaments due to the stabilization procedure and discusses the effect of filaments on subsequent testing.Two separate catalysts were used in this study. The first was a 50,000 mile vehicle aged catalyst that had also been through the stabilization procedure and then sweep and light-off tested. The other was only dynamometer aged for 120hr at 850°C (1560°F).

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Second Life Application of Automotive Catalysts: Hydrodynamic Cavitation Recovery and Photo Water Splitting

Metals ◽

10.3390/met10101307 ◽

2020 ◽

Vol 10 (10) ◽

pp. 1307 ◽

Cited By ~ 1

Author(s):

Adrian Ciocanea ◽

Eugeniu Vasile ◽

Viorel Ionescu ◽

Florentina Iuliana Maxim ◽

Cornelia Diac ◽

...

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Second Life ◽

Anatase Phase ◽

Particle Surface ◽

Hydrodynamic Cavitation ◽

Cubic Phase ◽

Shear Stresses ◽

Automotive Catalysts ◽

Transmission Electron

A hydrodynamic cavitation method was used to maximize the effect of destructuration of a honeycomb monolithic support of a spent Selective Catalyst Reduction (SCR) catalyst—V2O5-WO3/TiO2-type—for extracting crystalline titanium and tungsten oxides from the cordierite surface. A high relative inlet pressure of 40 MPa was applied to a divergent nozzle for obtaining high shear stresses of the submerged cavitating jets and intensive micro- and nano-jets and shock waves acting on the particle surface of the milled catalyst. Scanning Electron Microscopy (SEM) analysis indicated the compact morphology of the thin metal oxide layer at the surface of the cordierite support and the high content of Ti and W elements in the sample. Energy dispersive spectroscopy (EDAX) performed along with TEM investigations on different nano-zones from the sample established the elemental composition of WO3-TiO2 agglomerates separated after hydrodynamic cavitation processing and identified as independent nanocrystalline structures through Bright Field Transmission Electron Microscopy (BF-TEM) and High Resolution Transmission Electron Microscopy (HR-TEM) measurements. The tetragonal anatase phase of TiO2 and cubic phase of WO3 were established by both interplanar d spacing measurements and X-ray diffraction analysis. The photoelectrochemical results showed the possible second life application of automotive catalysts.

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