Cobalt standard catalyst

The introduction of iron-zinc catalysts led to the low pressure nthesis of liquid and solid hydrocarbons from CO/Hj in 1925 [19. 20. However, it was found that these catalysts were deactivated rapidly and thus further investigations concentrated on nickel and cobalt catalysts. They led to the introduction of a standardized cobalt-based catalyst for llic normal-pressure synthesis of mainly saturated hydrocarbons at temperatures below 200 C. In 1936, the first four commercial plants went on stream. Until 1945 the Fischer-Tropscit synthesis was carried out in nine plants in Germany, one plant in France, four plants in Japan and one plant in Manchuria. The total capacity amounted to approximately one million tons of hydrocarbons per year in 1943. The catalysts used consisted of Co (1(X) parts), ThO (5 parts). MgO (8 parts), and kieselgur (200 parts) and were prepared by precipitation of the nitrates. These catalysts were used in fixed-bed reactors at normal or medium pressures (< 10 bar) and produced mainly saturated straightproduct obtained consisted of 46% gasoline. 23% diesel oil, 3% lubricating oil and 28% waxes (3.15). 

Catalyst Characterization. Chemical analyses, x-ray diifraction analyses, and gas adsorption procedures were used to characterize the composition, crystallographic character, and surface structure of the nickel and cobalt zeolite catalyst preparations. The chemical and x-ray procedures were standard methods with the latter described elsewhere 11). Carbon monoxide chemisorption measurements provide useful estimates of the surface covered by nickel atoms from the zeolite substrate 10). 

The performance of several of the nickel and cobalt zeolite catalysts for steam reforming of n-hexane at 400°-500°C has been evaluated by short test runs with the reactor and the procedures described above (Table II). A Girdler reforming catalyst (G56) was tested under the same conditions as a comparative standard. All tests were conducted at a total pressure of 1 atm. Plateaus of sustained reforming activity were established within 1 hour. The cobalt catalysts lost essentially all reforming activity within 3 hours, presumably because of oxidation by steam. The space velocities reported are calculated in terms of theoretical hydrogen production based on the n-hexane injection rate and extent of conversion (Equation 2, Table II). The equation for the steam reforming of n-hexane with complete conversion to carbon dioxide is... 

Cobalt precipitation catalysts. The development of cobalt catalysts (Fischer and Koch, 12) was similar to the development of the corresponding nickel catalysts. In the case of cobalt, however, it was easier to prevent extensive methane formation. The lOOCo 18Th02 100 kieselguhr catalyst became the so-called standard cobalt catalyst. 

For desulfurization of naphtha, a more complicated process is required. Hydrodesulfurization quite often is used. About 0.5 mole of H2 is mixed with 1 mole of vaporized naphtha or 250 scf (Standard Cubic Feet) per barrel, depending upon the sulfur and olefin content. The mixture is preheated to 320 "C and passed over a cobalt-molybdenum catalyst, where the olefins are hydrogenated to paraffin hydrocarbons and the sulfur compounds are reduced to H2S. The gas then is passed over a sulfur adsorbent such as iron or zinc oxide. It may or may not be necessary to condense the naphtha, depending upon the amount of hydrogen used and the need to remove it from the naphtha. 

To close on the new cyclization partners used in cobalt-catalyzed [2 + 2 + 2] cycloaddition to give benzene derivatives, it is worth mentioning that alkynyl halides have been used for the first time in this transformation [29]. Until then, only ruthenium-based catalysts had been used with such substrates [30]. While the standard catalysts CpCo(CO)2 and CpCo(C2H4)2 did not allow the formation of cycloadducts, the new catalyst III proved able to accomplish this task efficiently starting from alkynyl bromides 59 and 62 (Scheme 1.15). 

Sulfite reacts readily with oxygen, particularly under hot, alkaline conditions, but the reaction rate is slow in colder, neutral waters thus complete FW deaeration cannot be guaranteed. Consequently, it is standard practice to add a small amount of catalyst to the sulfite. The catalyst is usually cobalt sulfate [more properly, cobaltous sulfate (CoS04) supplied as an anhydrous, monohydrate, or heptahydrate salt] or sometimes cobaltous nitrate. The catalyst is added to 100% sodium sulfite at a concentration level of 0.2 to 0.25%. 

This type of catalyst is not limited to nickel other examples are Raney-cobalt, Raney-copper and Raney-ruthenium. When dry, these catalysts are pyrophoric upon contact with air. Usually they are stored under water, which enables their use without risk. The pyrophoric character is due to the fact that the metal is highly dispersed, so in contact with oxygen fast oxidation takes place. Moreover, the metal contains hydrogen atoms and this adds to the pyrophoric nature. Besides the combustion of the metal also ignition of organic vapours present in the atmosphere can occur. Before start of the reaction it is a standard procedure to replace the water by organic solvents but care should be taken to exclude oxygen. Often alcohol is used. The water is decanted and the wet catalyst is washed repeatedly with alcohol. After several washes with absolute alcohol the last traces of water are removed. 

It was concluded that in this case an equilibrium existed which gave 100 ppm of soluble cobalt at reaction temperature. The polymer support acted as a reservoir for furnishing soluble metal at reaction temperature and reabsorbing it after completion (about 10 ppm in the product after cooling to ambient temperature). The rate approximated that obtained in a standard cobalt reaction with 100 ppm of cobalt catalyst. 

While cobalt and rhodium have been the focus of most research and are the metals of choice for commercial hydroformylation reactions, numerous other metals have been disclosed as catalysts in the patent literature. However, only some of the carbonyl-forming metals can be seriously considered. Even of these, a comparison of relative reactivity (118) based on cobalt as the standard indicates a decided preference for only two or three metals. This listing may be considered incomplete without the inclusion of platinum and copper, which have recently received significant attention (vide infra). 

Amoco Amoco Chemicals Company, a subsidiary of Amoco Corporation, formerly Standard Oil Company (IN), is best known in the chemicals industry for its modification of the Mid-Century process for making pure terephthalic acid. /7-Xylene in acetic acid solution is oxidized with air at high temperature and pressure. Small amounts of manganese, cobalt, and bromide are used as catalysts. The modification allows the use of terephthalic acid, rather than dimethyl terephthalate, for making fiber. The process can also be used for oxidizing other methylbenzenes and methylnaphthalenes to aromatic carboxylic acids. See also Maruzen. 

Meanwhile attempts to find an air oxidation route directly from p-xylene to terephthalic acid (TA) continued to founder on the relatively high resistance to oxidation of the /Moluic acid which was first formed. This hurdle was overcome by the discovery of bromide-controlled air oxidation in 1955 by the Mid-Century Corporation [42, 43] and ICI, with the same patent application date. The Mid-Century process was bought and developed by Standard Oil of Indiana (Amoco), with some input from ICI. The process adopted used acetic acid as solvent, oxygen as oxidant, a temperature of about 200 °C, and a combination of cobalt, manganese and bromide ions as catalyst. Amoco also incorporated a purification of the TA by recrystallisation, with simultaneous catalytic hydrogenation of impurities, from water at about 250 °C [44], This process allowed development of a route to polyester from purified terephthalic acid (PTA) by direct esterification, which has since become more widely used than the process using DMT. 

In a one-pot process for the preparation of the complexes from cobalt(II) nitrate, which is converted into the tetracarbonyl anion by the standard procedure [9], higher yields of (2) are claimed (R = Cl, 42% R = Br, 36% R = H, 30%) using cetyltrimethylammonium bromide as the catalyst. It is known that the cluster compounds are unstable under basic conditions and it was noted that, for example, in the preparation of the chloro compound, extended reaction times (4.5 hours) resulted in the total decomposition of the product [10]. 

Because of the enhanced effectiveness of the cobalt(III) complex with piperidinium end-capping arms (Scheme 6) compared to standard (salen)CoX catalysts for the copolymerization of propylene oxide and CO2, Nozaki and coworkers were able to prepare in a stepwise manner a tapered block terpolymer by first copolymerizing propylene oxide/C02 followed by 1-hexene oxide/C02 [31]. 

Further evidence has been obtained to support the contention that the active catalysts are metal complexes dissolved in solution. With experiments reported in Table II, the kinetics of oxidation under standard conditions in the presence of various metal salts are compared with the rates of reaction when solid residues have been filtered from solution. The agreement between the rates in Cases 1 and 3 of Table II (where the amount of metal available is dictated by the solubility of metal complexes) shows that solid precipitates play little or no part in catalysis in all the systems studied. The amount of metal in solution has been measured in Cases 2 and 3 metal hydroxide complexes (Case 2) are not as soluble as metal-thiol complexes, and neither is as soluble as metal phthalocyanines (19). The results of experiments involving metal pyrophosphates are particularly interesting, in that it has previously been suggested that cobalt pyrophosphates act as heterogeneous catalysts. The result s in Table II show that this is not true in the present system. 

Peracetic Acm-AcErALDEHYDE Reaction. The cobalt- and manganese-catalyzed reactions of peracetic acid with acetaldehyde were studied by a continuous flow technique (9). Peracetic acid (0.15M in acetic acid) and acetaldehyde-catalyst solutions were metered through rotameters to a mixing T (standard 0.25-inch stainless steel Swagelok T) and... 

The catalyst used in the experiments was a commercial cobalt molybdenum supported on y-alumina (Procatalyse HR306). It contains 14 wt% of molybdenum oxide and 3 wt% of cobalt oxide and has a surface area of 210 m2/g. It was sulfided according to a standard laboratory procedure at 400 °C under a mixture of 15 vol.% of H2S in H2. In one experiment, the activity of... 

The method of preparation of the catalyst has been found to alter the effect of the promoter (196). With standard VPO prepared with an organic solvent, the effects of cobalt and of iron were found to be the same as those previously described 182,193-195,202,208). The improvement in catalytic performance is proposed to be a consequence of the stabilization of dimers, which are the proposed active sites. However, catalysts prepared from V0P04 2H2O in organic solvents are not characterized by a promotional effect of iron. This lack of promotion is attributed to the loss of crystallinity and surface area of the rosette crystals formed by in the preparation. Similarly, the increase in activity attributed to cobalt is thought to be a structural effect, influencing the development of the (100) plane of (VO)2P207. 

The standard cobalt catalysts which were used in Germany from 1936 to 1945 were prepaied by precipitation of the metal nitrates with sodium carbonate. It was soon found that the presence of chlorides or sulfates was detrimental to the catalytic activity. After nitration, the catalyst cake was extruded, dried and reduced in a hydrogen atmosphere at 400 0. About 50- 60% of the cobalt is... 

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