Poisoning studies

It is interesting to note that quantities of phenylarsonic acid sufficient to decrease the rate of reduction of crotonic acid with Pd-PVA colloidal catalyst, to / of the unpoisoned value have no effect on the reduction of nitrobenzene (27) in the presence of the same catalyst. The reason for this behavior is not known. 

Berkman, S., Morrell, J. C., and Egloff, G., Catalysis. Reinhold Publishing Corporation, New York, 1940. 

Ueber Katalytische Reduktionen organ. Verbindingen. Enke, Stuttgart, 1912. 

Naumann, C. F., and Zirkel, F., Elemente der Mineralogie, 15th edition, p. 421. Engelmenn, Leipzig, 1907. 

Sncony-Vacuum Laboratories (A Division of Socony-Vacuum Oil Co., Inc.), Research and Development Department, Paulsboro, New Jersey 

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N02 at concentrations up to 8 ppm(v) in the inlet gas did not poison the C150-1-03 catalyst. The location of the hot spot fluctuated between the 31 and 44% levels. The hot spot did not drop sharply down into the catalyst bed as it had during the poisoning studies with H2S and HC1. 

Benzene. Benzene is ordinarily scrubbed out by a Rectisol system before the methanators. However, if a different H2S removal system were used, benzene could pass through the system and then hydrogenate, plug up the catalyst pores, or reform. Benzene was therefore included in this poison study. 

Chisolm JJ Jr, Harrison HC, Eberlein WR, et al. 1955. Aminoaciduria, hypophosphatemia, and rickets in lead poisoning Study of a case. Am J Dis Child 89 159-168. 

FIGURE 2.26 Change of cell performance versus time for anode-supported cells subject to different concentrations of H2S poison. (From Sprenkle, V. et al., Sulfur Poisoning Studies on the Delphi-Battelle SECA Program, 2007. Permission pending.)... 

Sprenkle V, Kim JY, Meinhardt K, Lu C, Chick L, Canfield N et al. Sulfur poisoning studies on the Delphi-Battelle SECA program. Presented at The 31st International Cocoa Beach Conference and Exposition on Advanced Ceramics and Composites, 2007 Daytona Beach, FL. 

Subcommittee on Accidental Poisoning. 1962. Co-operative kerosene poisoning study Evaluation of gastric lavage and other factors in the treatment of accidental ingestion of petroleum distillate products. Pediatrics 648-674. 

Xu, W. Adler, I.-D. (1990) Clastogenic effects of known and suspect spindle poisons studied by chromosome analysis in mouse bone marrow cells. Mutagenesis, 5, 371-374... 

These catalysts have been used in air wet-oxidation processes, where catalysts are essential to obtain high efficiencies [9]. In SCWO processes these efficiencies can be obtained by increasing temperature, and therefore they are not considered necessary. Catalysts studies have been performed on synthetic mixtures, and poisoning studies should be made when using wastewater. 

Catalyst-poisoning studies have concentrated on the potential poisons introduced with fuel, particularly on lead, which has been added intentionally to improve the combustion characteristics at the high compression ratios employed in modem internal combustion engines prior to the introduction of exhaust purification catalysts. The lead is usually introduced as motor mix which contains tetraethyllead in a mixture with organic halides, chlorides or bromides. These halides transport the lead in the form of volatile halides out of the engine and into the exhaust, and are hence termed lead scavengers. Thus the potential catalyst-poison elements associated with the additive mixture are Pb, Br, and Cl. 

Poisoning studies carried out by several groups have shown that the equivalents of poison needed to quench the catalytic activity of the dealuminated Y-type zeolites are much less than the number of Alf atoms. Beyerlein et al. (9) reported that residual sodium cations extensively decreased the isobutane cracking activity of steam-dealuminated Y-type zeolites. From their results it was concluded that only one-third of the Alf atoms were associated with strong acidity throughout the Si/Al > 5 composition domain. 

Chronic effects of arsenic poisoning include neurotoxic effects to the central and peripheral nervous systems. Symptoms include sensory changes, muscle sensitivity, prickling and tingling sensations (paresthesia), and muscle weakness. Liver injury is a common symptom of chronic arsenic poisoning. Studies of victims of chronic arsenic poisoning from contaminated drinking... 

Table II. A Brief Summary of Literature Relating Generally to Reactivity—Selectivity-Poisoning Studies of Bimetallic Catalysts...

Acid catalysts such as zeolites can be readily poisoned by basic organic compounds. One of the earlier studies of the deactivation of silica-alumina cracking catalysts by organic nitrogen compounds such as quinoline, quinaldine, pyrrole, piperidine, decylamine and aniline was done by Mills et al (6). The results of their partial poisoning studies showed an exponential dependence of the catalyst activity for cumene cracking reaction or... 

On the basis of the poisoning studies, the number of active sites of the catalyst were 1.63 x 10 per gram obtained from pyridine poisoning and cumene cracking reaction at 300°C. This number is close to the number reported by Jacobs and Heylen (13) in the study of poisoning with 2,6-methylpyridine of cumene cracking activity of the HY zeolites. 

Specific poisoning studies with pyridine and TCNE have led to this picture that excludes the participation of Lewis acid sites in the reaction. It should, however, be mentioned that this interpretation of the reaction mechanism is not completely undisputed. Thus, Soma and co-workers (351) conclude from their dynamic treatment that a surface alkoxide species is the intermediate in olefin formation. Since the alkoxide is formed by dissociative adsorption on A1—O pair sites, one would expect a strong poisoning effect by pyridine. Bremer and co-workers (352, 353) propose a mechanism in which a coordinated held alcohol molecule... 

The catalyst used in this study is a model FCC catalyst with composition zeolite US-Y (30%), silica hinder (25%), kaolin (25%) and pseudo boehmite alumina matrix (20%)-Hexadecane was used as feedstock and in the catalyst poisoning studies 10% by volume quinoline or phenanthrene were added to the hexadecane. Reactivity and coking were determined using a standard MAT reactor test (6). 

Sulphur-poisoning studies of nickel catalysts have been performed with fixed-bed tube reactors at 800 - 950 °C under 1 - 20 bar total pressure with real and simulated gasification gas mixtures containing H2S (50 - 1000 ppmv). The effect of sulphur concentration of the gas and the operation conditions will be presented and discussed in this paper. 

Figure 32 shows the steady-state methanation activity of Ni, Co, Fe, and Ru relative to the fresh, unpoisoned surface activity as a function of gas-phase H2S concentration. These data indicate that Ni, Co, Fe, and Ru are all similarly extremely sensitive to poisoning by very low H2S concentrations (15-100 ppb). These results predict that, in principle, poisoning studies of... 

Microcatalytic reactor can be used for surface chemistry and poisoning studies by slug techniques (see Fig. 5-15). 

Data of Figure 2 clearly show that the used anatase catalyst produces less Cl than the fresh catalyst. Poisoning studies with titania... 

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