Formation, catalyst

Trioctylamine has been prepared, in a continuous process, using 5,200 kg of -octanol, 100 kg of copper formate catalyst, 500 kg of -octylamine, 10 kg of calcium hydroxide, and 240 kg of ammonia (58). Ammonia was added over a 10-h period while 10 m of hydrogen/h was passed through the reactor at a reaction temperature of 180—200°C. The final product was composed of 94% trioctylamine, 2% dioctylamine, 1% octylamine, and 0.5% -octanol. A... 

Dry reduced nickel catalyst protected by fat is the most common catalyst for the hydrogenation of fatty acids. The composition of this type of catalyst is about 25% nickel, 25% inert carrier, and 50% soHd fat. Manufacturers of this catalyst include Calsicat (Mallinckrodt), Harshaw (Engelhard), United Catalysts (Sud Chemie), and Unichema. Other catalysts that stiH have some place in fatty acid hydrogenation are so-called wet reduced nickel catalysts (formate catalysts), Raney nickel catalysts, and precious metal catalysts, primarily palladium on carbon. The spent nickel catalysts are usually sent to a broker who seUs them for recovery of nickel value. Spent palladium catalysts are usually returned to the catalyst suppHer for credit of palladium value. 

Certain catalyst properties appear to increase coke formation. Catalysts with high rare earth content tend to promote hydrogen transfer reactions. Hydrogen transfer reactions are bimolecular reactions that can produce multi-ring aromatics. 

Ethanol and methane steam reforming reactions were studied assuming that the exit composition of the ethanol reformer depends on the steam reforming of methane. The competition for the same active site for ethanol and methane reforming maximizes the H2 and C02 production and minimizes the CO formation Catalysts were prepared by incipient wet impregnation. 20 wt% Ni supported on ZnO exhibited better performance compared to that supported on La203, MgO and A1203... 

Aqueous phase reforming of glycerol in several studies by Dumesic and co-workers has been reported [270, 275, 277, 282, 289, 292, 294, 319]. The first catalysts that they reported were platinum-based materials which operate at relatively moderate temperatures (220-280 °C) and pressures that prevent steam formation. Catalyst performances are stable for a long period. The gas stream contains low levels of CO, while the major reaction intermediates detected in the liquid phase include ethanol, 1,2-pro-panediol, methanol, 1-propanol, propionic acid, acetone, propionaldehyde and lactic acid. Novel tin-promoted Raney nickel catalysts were subsequently developed. The catalytic performance of these non-precious metal catalysts is comparable to that of more costly platinum-based systems for the production of hydrogen from glycerol. 

In principle, the attainment of chemical equilibrium can be accelerated by catalysts however, in contrast to polyester formation, catalysts are not absolutely essential in the above-mentioned polycondensations. The first two types of reactions are generally carried out in the melt solution polycondensations at higher temperature, e.g., in xylenol or 4-fert-butylphenol are of significance only in a few cases on account of the poor solubility of polyamides. On the other hand, polycondensation of diamines with dicarboxylic acid chlorides can be carried out either in solution at low temperature or as interfacial condensation (see Sect. 4.1.2.3). 

We conclude that most reaction systems in the chemical industries are exothermic. This has some immediate consequences in terms of unit operation control. For instance, the control system must ensure that the reaction heat is removed from the reactor to maintain a steady state. Failure to remove the heat of reaction would lead to an.accumulation of heat within the system and raise the temperature. Forreversible reactions this would cause a lack of conversion of the reactants into products and would be uneconomical. For irreversible reactions the consequences are more drastic. Due to the rapid escalation in reaction rate with temperature we will have reaction runaway leading to excessive by-product formation, catalyst deactivation, or in the worst case a complete failure of the reactor possibly leading to an environmental release, fire, or explosion. 

In the case of urethane-modification, two kinds of catalysts, i.e., urethane-formation catalysts and isocyanate-trimerization catalysts, are usually used. Major trimerization catalysts are listed in Table 11 and major urethane catalysts are listed in Tables 8 through 10. 

On the other hand, there is the question of the close relationship between coke formation (catalyst stability) and aromatics cyclization (catalyst selectivity) over the acid sites present in the zeolites. On naphtha reforming, coke formation is a bifunctional reaction requiring the dehydrogenation capacity of the metallic function and the condensation capacity of the acidic function. Therefore, it is interesting to... 

Pent-l-ene Hexanal (49), 2-methyl-pentanal (23) Co COUPPh), Toluene, 140 C (110/110) 6 20 No comments on alcohol formation, catalyst recoverable (200)... 

In addition, another important product was observed, furan (C4H4O, m/e 68 and 39) at 550 K with comparable yield to acetaldehyde (42 % carbon selectivity). Thus, furan formation indicated that U surfaces are also active for C-C bond formation in their oxidised form, in addition of being an active C-0 bond formation catalyst. The key route to this reaction is the formation of C4 olefin (most likely butadiene) which in its turn reacts with the surface oxygen to give furan as follow... 

Rate performance based on byproduct formation, catalyst deactivation, and dependence of hydrogen yield and conversion... 

Froment, G. F. The modeling of catalyst deactivation by coke formation. Catalyst Deactivation 1991 C. H. Bartholomew J. B. Butt (Eds.) Elsevier Sciences Amsterdam, 1991,53. 

No definite decision can be made at the moment with regard to the correctness of the points above. However, the following considerations are relevant. (/) When a Rh, Co, or Ru catalyst is prepared from suitable carbonyls by decomposition at high temperature, some oxygen can be retained and oxide-like structures formed, (n) Results obtained by Somorjai et al. can also be rationahzed by an assumption that Rh rather than Rh forms an active centre for alcohol formation, or at least for some steps of the alcohol formation. (///) Catalyst components which can be expected to stabilize Rh ions are suitable supports and promoters of Rh catalysts for oxygenates. (iV) The temperature of reduction of Rh catalysts has in most cases been not very high, which also points to the possibility that some Rh centres may remain in the active catalysts. In our opinion these points together are an... 

With aryl isocyanates in general pentavalent phosphorus compounds could act as carbodiimide formation catalysts. In addition trivalent phosphorus compounds such as triethyl phosphine are also efficient carbodiimide catalysts [8b]. 

Methylation with j CH3CI and - phase trans formation catalyst (PTC)... 

NH3 oxidation Pt/Rh R As, Sb compounds Pb, Zn, Cd, Bi poison alloy formation, catalyst net becomes brittle... 

Conductive additives proposed in the literature as formation catalysts include the following ... 

Asymmetric reductive amination of a dialkyl ketone by an alkylamine, catalysed by (193), formed the diazepane ring (194) with >97% yield and >94% ee. Purging of the by-product CO2 resulted in increased rate and almost quantitative yield of the product which otherwise formed carbamates with CO2 an adverse effect on the equilibrium between Ru-hydride and Ru-formate (catalyst forms) was thereby avoided. The rate could also be accelerated by trapping with nucleophilic secondary amines. ... 

Reaction conditions N,lV-Diinethylfomiamide, room temperature Synthetic strategy Ligand-free Pd/C-catalyzed C-S bond formation Catalyst Pd/C... 

Load cycling Cathode catalyst surface area loss Membrane pinhole formation Catalyst dissolution by potential cycle Mechanical stress by hydration, pressure and thermal cycle... 

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