Promoters potassium oxide

Several pilot plants have been built to test periodic flow direction reversal. Pilot-scale reactors with bed diameters from 1.6 to 2.8 m were operated with flow reversal for several years. The units, described by Bunimovich et al. (1984,1990) and Matros and Bunimovich (1996), handled 600 to 3000 m3/h and operated with cycle periods of 15 to 20 min. Table VIII shows the performance of these plants for different feeds and potassium oxide promoted vanadia catalysts. The SVD catalyst was granular the IK-1-4 was in the form of 5 (i.d.) x 10-mm cylinders, while the SYS catalyst was... 

This work involved the study by TPSR in H2 of carbon and carbide species formed in iron catalysts during FT synthesis for up to 18 hours under steady-state conditions or up to 6 hours under severe, deactivating reaction conditions. The effects of reaction temperature and potassium oxide promotion on the distribution of carbon types were also determined. 

By a similar mechanism to that proposed for the formation of ethyl ether by dehydration of ethanol, it is possible that the reaction occurs stepwise with the intermediate dehydration of one ethanol molecule to form ethylene which then reacts with another ethanol molecule to form butanol. It is thus possible that higher alcohols may be built up by the reaction of olefins with the lower alcohols. Mixed oxide type of catalysts are used in the process of a nature similar to those which have been found effective in alcohol synthesis from hydrogen and carbon monoxide. It should lie noted here that catalysts which promote the union of carbon atoms must be used, and since potassium oxide promoted catalysts composed of mixtures of zinc, copper, or chromium oxides have been found to be effective in the syuthesis of higher alcohols, such catalysts should be useful in promoting the addition of olefins to alcohols or other oxygenated organic molecules.77... 

A similar chemisorption can take place on other metals which do not form a nitride from N2. The much lower ability of other metals to chemisorb N2 seems to come primarily from the difficulty in activating the N2 molecule. Even a copper surface can chemisorb N2 when the copper surface is activated by ion bombardment [34], even though copper nitride, CU3N, is unstable. Chemisorption of N2 was found on reduced cobalt oxide with a potassium oxide promoter at room temperature [35, 36] and even on noble metals (Ru, Rh,... 

The fixed-bed catalyst is a siUca-based extmdate containing precipitated iron oxide promoted with potassium and copper. The catalyst is activated by hydrogen reduction of most of the iron cataly2ed by small amounts of copper. As the catalyst is used, additional reduction occurs and Hagg carbide [12127 5-6] Fe C2, is formed. 

A characteristic feature of aromatic fluorodenitration is modest yield due to side reactions promoted by potassium nitrite and/or its decomposition product, potassium oxide, with the aryl fluoride or starting material... 

Dehydrochlorination of bis(tnfluoromethylthio)acetyl chloride with calcium oxide gives bis(trifluoromethylthio)ketene [5] (equation 6) Elimination of hydrogen chloride or hydrogen bromide by means of tetrabutylammonium or potassium fluoride from vinylic chlorides or bromides leads to acetylenes or allenes [6 (equation 7) Addition of dicyclohexyl-18-crown-6 ether raises the yields of potassium fluoride-promoted elimination of hydrogen bromide from (Z)-P-bromo-p-ni-trostyrene in acetonitrile from 0 to 53-71 % In dimethyl formamide, yields increase from 28-35% to 58-68%... 

The modem process uses a potassium-sulfate-promoted vanadium(V) oxide catalyst on a silica or kie,selguhr support. The SO2 is obtained either by burning pure sulfur or by roasting sulfide minerals (p. 651) notably iron pyrite, or ores of Cu, Ni and Zn during the production of these metals. On a worldwide basis about 65% of the SO2 comes from the burning of sulfur and some 35% by the roasting of sulfide ores but in some countries (e.g, the UK) over 95% conies from the former. 

Increasing the temperature increases the reaction rate, but decreases the equilibrium (K 500°C = 0.08). According to LeChatlier s principle, the equilibrium is favored at high pressures and at lower temperatures. Much of Haber s research was to find a catalyst that favored the formation of ammonia at a reasonable rate at lower temperatures. Iron oxide promoted with other oxides such as potassium and aluminum oxides is currently used to produce ammonia in good yield at relatively low temperatures. 

Small amounts of other compounds can be added to Ni-based catalysts to improve the functional characteristics of the final catalyst. Typically, they are calcium aluminate to enhance the mechanical resistance of the catalyst pellets, potassium oxide to improve the resistance to coke formation and silica to form a stable silicate with potassium oxide [34]. Promotion with rare earth oxides such as La2C>3 also results in enhanced resistance to coking. 

It is of importance to draw a distinction between additions which are sensitive toward oxygen and those which are not sensitive toward oxygen. For instance, metallic potassium, under the influence of oxygen, forms potassium oxide, and the promoting effect of the latter differs from that of the alkali-metal. The same element can act on the catalyst differently, depending on whether it is present as the oxide, chloride, or other compound. ... 

PROMOTER. 1. A substance that, when added m relatively small quantities to a catalyst, increases its activity, e.g., aluminum and potassium oxide are added as promoters to the iron catalyst used in facilitating a combination of hydrogen and nitrogen to form ammonia. 

Promoter. In some cases, a relatively small quantity of one or more substances, the promoter or promoters, when added to a catalyst improves the activity, the selectivity, or the useful lifetime of the catalyst. In general, a promoter may either augment a desired reaction or suppress an undesired one. There is no formal system of nomenclature for designating promoted catalysts. One may, however, for example, employ the phase iron promoted with alumina and potassium oxide. ... 

Ammonia synthesis catalysts have traditionally been based on iron and have been made by the reduction of magnetite (Fe304). The difference between different commercially available products lies in optimized levels of metal oxide promoters that are included within the magnetite structure. These metal oxides promote activity and improve the thermal stability of the catalyst. Typical promoters are alumina (AI2O3X potassium oxide (K2O), and calcium oxide (CaO). The interactions between the many components in the catalyst can radically affect 1) the initial reducibility, 2) the level of catalyst activity that is achieved, 3) the long-term catalyst performance and 4) the long-term catalyst stability204. 

The potassium oxide is an electronic promoter. It increases the intrinsic activity of the high- surface-area iron particles that are produced when reduction... 

Tanner, D. and S. Osmar (1987). Oxidative decarbonation on the mechanism of potassium persulfate promoted decarbonation reaction. J. Org. Chem. 52,4689-4693. 

Effects of Catalysts. It has been found that copper chromite, potassium dichromate, and magnesium oxide promote the deflagration of hydrazine perchlorate. Since none of these additives has any fuel content, they must be considered to be catalysts. The results of experiments with these additives are shown in Table IV. Experiments were performed both with pressed (p 1.9 grams/cc.) and tamped (p 1.1. grams/cc.) strands. 

The ammonia synthesis catalyst problem could be considered solved when the catalytic effectiveness of iron in conversion and its onstream life were successfully and substantially improved by adding reduction-resistant metal oxides [232] (Table 15). The iron catalysts promoted with aluminum and potassium oxides proved to be most serviceable [238]. Later, calcium was added as the third activator. Development work in the United States from 1922 can be found in [239]. 

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