“Dead zone” in a porous catalyst granule for a nonstationary parallel reaction

2006 ◽  
Vol 80 (4) ◽  
pp. 535-540 ◽  
Author(s):  
V. V. Andreev
1985 ◽  
Vol 29 (1) ◽  
pp. 71-77 ◽  
Author(s):  
V. Kh. Fedotov ◽  
B. V. Alekseev ◽  
N. I. Koltsov
Keyword(s):  

1995 ◽  
Vol 5 (4) ◽  
pp. 152-153 ◽  
Author(s):  
Vsevolod V. Andreev ◽  
Nikolai I. Koltsov ◽  
Anna F. Ivanova ◽  
Nataliya V. Konstantinova

2019 ◽  
Author(s):  
M. Alexander Ardagh ◽  
Manish Shetty ◽  
Anatoliy Kuznetsov ◽  
Qi Zhang ◽  
Phillip Christopher ◽  
...  

Catalytic enhancement of chemical reactions via heterogeneous materials occurs through stabilization of transition states at designed active sites, but dramatically greater rate acceleration on that same active site is achieved when the surface intermediates oscillate in binding energy. The applied oscillation amplitude and frequency can accelerate reactions orders of magnitude above the catalytic rates of static systems, provided the active site dynamics are tuned to the natural frequencies of the surface chemistry. In this work, differences in the characteristics of parallel reactions are exploited via selective application of active site dynamics (0 < ΔU < 1.0 eV amplitude, 10<sup>-6</sup> < f < 10<sup>4</sup> Hz frequency) to control the extent of competing reactions occurring on the shared catalytic surface. Simulation of multiple parallel reaction systems with broad range of variation in chemical parameters revealed that parallel chemistries are highly tunable in selectivity between either pure product, even when specific products are not selectively produced under static conditions. Two mechanisms leading to dynamic selectivity control were identified: (i) surface thermodynamic control of one product species under strong binding conditions, or (ii) catalytic resonance of the kinetics of one reaction over the other. These dynamic parallel pathway control strategies applied to a host of chemical conditions indicate significant potential for improving the catalytic performance of many important industrial chemical reactions beyond their existing static performance.


1998 ◽  
Vol 37 (1) ◽  
pp. 215-222
Author(s):  
I. Guymer ◽  
R. O'Brien ◽  
O. Mark ◽  
P. Dennis

Previous studies of the effects of manholes on longitudinal dispersion has concentrated on the spreading of solutes. This papers presents new data describing the influence of a surcharged and free-flowing manhole structure on the longitudinal dispersion of a fine suspended material. The effects of benching within the manhole structure are also illustrated. Laser Induced Fluorescence (LIF) techniques have been used to provide a qualitative description of the mixing processes present within a surcharged manhole. Nephelometric results have provided estimates of the parameters required to simulate the mixing effects using either increase in variance or aggregated dead zone techniques. A preliminary attempt at describing these observations using available software is discussed and recommendations for future developments are made.


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