Catalyst high-temperature

Nickel carbonyl charged, or formed in the carbonylation reaction mixture, can catalyze the carbonylation of methanol (11). To maintain the activity of the nickel carbonyl catalyst high temperature and pressure are required (12-14). However, certain promoters can maintain an active, soluble, nickel carbonyl species under much milder conditions. The most reactive promoters are phosphines, alkali metal salts, tin compounds, and 2-hydroxypyridine. Reaction rates of 2 to 7 X 10-3(mol/1.sec) can be achieved without the use of high concentration of iodine (Table II). in addition, high reaction rates... 

Metal oxides on zeolites have also found use as redox catalysts. High-temperature (700-750 °C) dehydroaromatization of methane under nonoxidizing conditions has been explored with a number of zeolitic catalysts modified with transition metal ions. Although coke formation at these high temperatures is a problem, calcined molybdate-impregnated ZSM-5 shows unparalleled activity of up to 8 % methane conversion with 100 % selectivity towards aromatics. Surface studies of these Mo HZSM-5 catalysts indicate that M0O3 crystals are on the external zeolite surface [123]. 

Since the reaction is exothermic and the volume of ammonia formed is less than the combined volume of the reactants, the amount of ammonia formed at equilibrimn decreases as the temperature is increased and increases as the pressure is increased, in accordance with the Le Chateliei Braun principle. Without catal ts, the rate of reaching equilibrium is much too slow. Even with the best-promoted iron catalysts, high temperatures around bOCC are required to give a satisfactory rate of conversion. The rate of reaching equilibrium is still too slow, however, to permit the reaction to reach equilibrium in a single pass of the reactants through a converter, and unless several converters are operated in series, it is neces-... 

Pt/C and PtCo/C catalysts High temperature operation effect on carbon corrosion, platinum dissolution, and sintering Arico et ai, 2008... 

Chen CS, Cheng WH, Lin SS (2004) Study of iron-promoted Cu/SiOz catalyst < high temperature reverse water gas shift reaction. Appl Catal Gen 257 97-106... 

Park JC, Bang JU, Lee J, Ko CH, Song H (2010) Ni Si02 yolk-shell nanoreactor catalysts high temperature stability and recyclahUity. J Mater Chem 20 1239-1246... 

Some of the attractive features of SOFC are (i) all solid components, (ii) compact, (iii) lower activation losses, (iv) more tolerant to the presence of impurities in the reactant gases, (v) flexible in fuel types, (vi) simpler fuel processing process, (vii) allows internal reforming, and (viii) no corrosion of cell components by liquid. High-temperature operation excludes use of expensive metal catalyst. High-temperature operation also provides a high-quality... 

Gas recycling requires additional heat exchange capacity, additional catalyst, and a blower. However, it is an efficient way of preventing first bed catalyst high-temperature degradation. 

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