Poisoning coefficient

The toxicity of a poison on a numerical scale is, as has already been stated, most conveniently expressed by the slope of the main linear portion of the poisoning graph, namely by the value of the poisoning coefficient, a, (see p. 160) for the poisons to be compared. The general effect of size is illustrated in Table IV (Maxted and Evans, 35) for two series... 

CH, HCHO and HCOOH were found in reformate generated from methanol (Narusawa et al. 2003). All three small organic molecules are present in minute quantities from either steam reforming or autothermal reforming. No adverse effect was observed from CH adsorption on platinum electrodes. On the other hand, both HCHO and HCOOH had a negative impact on fuel cell performance. It is estimated that the poisoning coefficient for HCHO is about 0.1 times that for CO, whereas the poisoning coefficient for HCOOH is only 0.004 times that for CO. 

Polymerization processes are characterized by extremes. Industrial products are mixtures with molecular weights of lO" to 10. In a particular polymerization of styrene the viscosity increased by a fac tor of lO " as conversion went from 0 to 60 percent. The adiabatic reaction temperature for complete polymerization of ethylene is 1,800 K (3,240 R). Heat transfer coefficients in stirred tanks with high viscosities can be as low as 25 W/(m °C) (16.2 Btu/[h fH °F]). Reaction times for butadiene-styrene rubbers are 8 to 12 h polyethylene molecules continue to grow lor 30 min whereas ethyl acrylate in 20% emulsion reacts in less than 1 min, so monomer must be added gradually to keep the temperature within hmits. Initiators of the chain reactions have concentration of 10" g mol/L so they are highly sensitive to poisons and impurities. 

Poison cell (free boundary method) Diffusion coefficient determination 3... 

This situation is termed pore-mouth poisoning. As poisoning proceeds the inactive shell thickens and, under extreme conditions, the rate of the catalytic reaction may become limited by the rate of diffusion past the poisoned pore mouths. The apparent activation energy of the reaction under these extreme conditions will be typical of the temperature dependence of diffusion coefficients. If the catalyst and reaction conditions in question are characterized by a low effectiveness factor, one may find that poisoning only a small fraction of the surface gives rise to a disproportionate drop in activity. In a sense one observes a form of selective poisoning. 

Chlorine (Cl), 6 130-211 9 280. See also Inorganic chlorine XeCl laser addition to fullerene, 12 240-241 analytical methods, 6 202 bleaching agent, 4 50 capacities of facilities, 6 193-198t catalyst poison, 5 257t chemical properties, 6 133-138 diffusion coefficient for dilute gas in water at 20° C, l 67t diffusion coefficient in air at 0° C, l 70t for disinfection, 8 605 economic aspects, 6 188-202 electrolytic preparation/production of, 12 759 16 40 end uses, 6 134-135 in fused quartz manufacture, 22 413 generating from hydrogen chloride, 13 833... 

By comparing the (57) - (59) we will obtain the expression for Poison s coefficient... 

Via the Young s module and the Poison s coefficient we find the shift module JU [2] ... 

Catalysts are porous and highly adsorptive, and their performance is affected markedly by the method of preparation. Two catalysts that are chemically identical but have pores of different size and distribution may have different activity, selectivity, temperature coefficient of reaction rate, and response to poisons. The intrinsic chemistry and catalytic action of a surface may be independent of pore size, but small pores appear to produce different effects because of the manner and time in which hydrocarbon vapors are transported into and out of the interstices. 

This shows that the inert C can strongly inhibit the unimolecular reaction of A, both by creating a rate inversely proportional to its partial pressure and by reducing the rate coefficient. Analysis of the coverages shows the cause of this. Species C blocks the sites on which A must adsorb to react, and lowers its coverage to a small value. This species is therefore a poison for the reaction. 

While the catalysts and conditions are very different than in ZN (water is a severe poison for ZN but is a product in FT), both produce linear polymers, and the molecular weight distributions are very similar because they are controlled by relative rate coefficients of propagation kp and termination k. If these are nearly independent of molecular weight one obtains the Schultz Flory size distribution in both processes. 

The model followed single-site, nondissociative, Langmuir-Hinshelwood poisoning. This resulted in the same adsorption coefficients for deactivation and start-of-cycle kinetics. 

Due to the fact that protein adsorption in fluidized beds is accomplished by binding of macromolecules to the internal surface of porous particles, the primary mass transport limitations found in packed beds of porous matrices remain valid. Protein transport takes place from the bulk fluid to the outer adsorbent surface commonly described by a film diffusion model, and within the pores to the internal surface known as pore diffusion. The diffusion coefficient D of proteins may be estimated by the semi-empirical correlation of Poison [65] from the absolute temperature T, the solution viscosity rj, and the molecular weight of the protein MA as denoted in Eq. (16). 

---