Nitrogen on catalysts

Fig. XVIII-13. Activation energies of adsorption and desorption and heat of chemisorption for nitrogen on a single promoted, intensively reduced iron catalyst Q is calculated from Q = Edes - ads- (From Ref. 130.)...

Calculate the entropy of adsorption A 2 for several values of d for the case of nitrogen on an iron catalyst. Use the data of Scholten and co-workers given in Section XVIII-4B. 

Table 10.1. Selectivity towards the formation of nitrogen on supported Pt-based catalysts at 300°C (initial partial pressure of NO and CO equal to 5 x 10 3 atm [37])...

When nitrogen was adsorbed at room temperature on the catalysts Ir-8, Ir-37, and Ir-100, an infrared absorption band due to adsorbed N was observed only on catalyst Ir-37. This was to be expected since the... 

Injuries and fatalities from asphyxiation are often associated with personnel entry into inerted equipment or enclosures. Guidance on safe procedures for confined space access are provided by OSHA (OSHA, 29 CFR 1910.146, Confined Space Entry Standard, 2000), the American National Standards Institute (ANSI, Z117.1, Safety Requirements for Confined Spaces, 2003), Hodson (Hodson, Safe Entry into Confined Spaces, Handbook of Chemical Health and Safety, American Chemical Society, 2001), and BP (BP, Hazards of Nitrogen and Catalyst Handling, 2003). OSHA has established 19.5 vol % as the minimum safe oxygen concentration for confined space entry without supplemental oxygen supply (see Table 23-18). Note that OSHA imposes a safe upper limit on 02 concentration of 23.5 vol % to protect against the enhanced flammability hazards associated with 02-enriched atmospheres. 

The objective of most research in the area of pyrolyzed metal/N/C materials has centered around understanding the nature of the active site for the ORR. Similar to heat-treated macrocycles, there has been a parallel controversy over the nature of the active sites and the role of Fe or Co in these metal-nitrogen-carbon catalysts. Based on the activity attainable from a wide-range of precursors, it seems safe to assume that above a certain temperature, the active site formed is the same regardless of the metal-nitrogen-carbon starting material (macrocycle or otherwise). Initially, some researchers believed that the metal clusters protected by a layer of carbon (which prevented leaching of the metal in the acidic electrolyte) were the source of catalytic... 

A wide range of carbon, nitrogen, and oxygen nucleophiles react with allylic esters in the presence of iridium catalysts to form branched allylic substitution products. The bulk of the recent literature on iridium-catalyzed allylic substitution has focused on catalysts derived from [Ir(COD)Cl]2 and phosphoramidite ligands. These complexes catalyze the formation of enantiomerically enriched allylic amines, allylic ethers, and (3-branched y-8 unsaturated carbonyl compounds. The latest generation and most commonly used of these catalysts (Scheme 1) consists of a cyclometalated iridium-phosphoramidite core chelated by 1,5-cyclooctadiene. A fifth coordination site is occupied in catalyst precursors by an additional -phosphoramidite or ethylene. The phosphoramidite that is used to generate the metalacyclic core typically contains one BlNOLate and one bis-arylethylamino group on phosphorus. 

Another part of our investigation deals with the effect of heat treatment on the leaching behavior of palladium on activated carbon catalysts. Heat treatment is a known technique to increase the performance of catalysts. (3) Therefore, standard carbon supported palladium catalysts were exposed to different temperatures ranging from 100 to 400 °C under nitrogen. The catalysts were characterized by metal leaching, hydrogenation activity and CO-chemisorption. 

This preparation requires 2 days. All manipulations are performed in Schlenk-type flasks under nitrogen dried over molecular sieves (4 A) and deoxygenated on catalyst BASF R3-11 (Imhoff Stahl). Tetrahydrofuran (THF) is dried over sodium benzophenone ketyl under N2. The complex Co2(CO)8 was purchased from Strem. 

At high temperatures with low catalyst concentration the formation of acetanilides is favored. Maleic anhydride and acetanilides may be formed directly from the mixed anhydride by an initial attack of the nitrogen on the acetate carbonyl, but this process would involve a seven membered ring transition state. Another possible route to the formation of maleic anhydride and the acetanilides is participation by neighboring carbonyl in loosening the amide carbon-nitrogen bond to the extent that the amine can be captured by acetic anhydride as shown in path D. 

Reaction (1) was carried out in n-hexane solvent. The excess butyl lithium was either removed by washing with n-hexane or decomposed by thermal treatment. Anchoring of palladium (reaction (2)) was carried out in acetone solution followed by washing with acetone and methanol. The formed Surface Complex (SC) was stabilized by thermal treatment in nitrogen at 100-3DDQC for 3 hours. Further details on catalyst preparation will be given in the Results and Discussion. ... 

The analysis of petroleum feedstocks for the percentages of carbon, hydrogen, nitrogen, oxygen, and sulfur is perhaps the first method used to examine the general nature, and perform an evaluation, of a feedstock. The atomic ratios of the various elements to carbon (i.e., H/C, N/C, O/C, and S/C) are frequently used for indications of the overall character of the feedstock. It is also of value to determine the amounts of trace elements, such as vanadium and nickel, in a feedstock since these materials can have serious deleterious effects on catalyst performance during refining by catalytic processes. 

Fastrup, B. (1994) Temperature programmed adsorption and desorption of nitrogen on iron ammonia synthesis catalysts, and consequences for the microkinetic analysis of NH3 synthesis. Top. Catal., 1, 273. 

The chemisorption of nitrogen on an iron ammonia catalyst was also studied by Emmett and Kummer 313), who found that the surface behaved as if it were of a homogeneous character. 

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