Carbon as promoter

Figure 2. Influence of temperature on reactor space time for 70% conversion of an aqueous solution of cobalt acetate (1% Co2+) activated carbon as promoter, 280 atm, CO H2...

Higher alcohol Same as above except with alkali oxides or carbonates as promoters 100-500 300-400 Methanol, isobutyl alcohol, and others... 

We have studied the synthesis of fatty acids by the closed Fischer-Tropsch process, using various carbonates as promoters and meteoritic iron as catalyst. The conditions used were D2/CO mole ratio = 1 1, temperature == 400°C, and time = 24-48 hr. Sodium, calcium, magnesium, potassium, and rubidium carbonates were tested as promoters but only potassium carbonate and rubidium carbonate produced fatty acids. These compounds are normal saturated fatty adds ranging from C5 to Cis, showing a unimodal Gaussian distribution without predominance of odd over even carbon-numbered aliphatic chains. The yields in general exceed the yields of aliphatic hydrocarbons obtained under the same conditions. The fatty acids may be derived from aldehydes and alcohols produced under the influence of the promoter and subsequently oxidized to the acids. 

DMF can also be manufactured from carbon dioxide, hydrogen, and dimethylamine ia the presence of halogen-containing transition-metal compounds (18). The reaction has also been performed with metal oxides and salts of alkaU metals as promoters (19). 

Both the equilibria and the enhancement of the coefficients can be improved by additives, of which sodium arsenite is the major one in use, but sodium hypochlorite and small amounts of amines also are effective. Sterically hindered amines as promoters are claimed by Say et al. (Chem. Eng. Prog., 80(10), 72-77 [1984]) to result in 50 percent more capacity than ordinary amine promoters of carbonate solutions. 

The enzyme carbonic anhydrase promotes the hydration of COg. Many of the protons formed upon ionization of carbonic acid are picked up by Hb as Og dissociates. The bicarbonate ions are transported with the blood back to the lungs. When Hb becomes oxygenated again in the lungs, H is released and reacts with HCO3 to re-form HgCOj, from which COg is liberated. The COg is then exhaled as a gas. 

The delocalization of molecular orbitals lies at the heart of modern chemistry. The concept that the tt orbitals of benzene or naphthalene cover the entire carbon skeleton promoted the successful understanding of conjugated molecules. The work of R. Hoffmann and others has proven that in saturated molecules [Pg.1]

The most successful class of active ingredient for both oxidation and reduction is that of the noble metals silver, gold, ruthenium, rhodium, palladium, osmium, iridium, and platinum. Platinum and palladium readily oxidize carbon monoxide, all the hydrocarbons except methane, and the partially oxygenated organic compounds such as aldehydes and alcohols. Under reducing conditions, platinum can convert NO to N2 and to NH3. Platinum and palladium are used in small quantities as promoters for less active base metal oxide catalysts. Platinum is also a candidate for simultaneous oxidation and reduction when the oxidant/re-ductant ratio is within 1% of stoichiometry. The other four elements of the platinum family are in short supply. Ruthenium produces the least NH3 concentration in NO reduction in comparison with other catalysts, but it forms volatile toxic oxides. 

The electrochemical promotion of 1-butene isomerization to 2-butene (cis-and trans-) using Nafion as the solid electrolyte and finely dispersed Pd deposited on carbon as the electrode has been described in section 9.2.2.14,15 Faradaic efficiency, A, values up to 28 were obtained in this remarkable study. The Pd dispersion is near complete on the high surface area C support.14,15... 

Nickel catalysts used in steam reforming are more resistant to deactivation by carbon deposition if the surface contains sulfur, or gold. Explain why these elements act as promoters. Would you prefer sulfur or gold as a promoter Explain your answer. 

All of the preparation procedures for the oxide promoted catalysts (T-O shared one common feature, heat-treatment of the oxide impregnated Ft on carbon catalysts in an inert atmosphere at elevated temperature, usually around 900 C. If an "alloy" phase of Ft with the metal of the metal oxide is formed by this heat-treatment, thermal reduction would have to occur with carbon as reducing agent, e.g. 

Besides N-alkylation reactions, there are also reports in the literature concerning microwave-promoted O-alkylations. A mild method for the O-alkylation of phenols with alkyl bromides and chlorides has been developed by Wagner and coworkers (Scheme 6.117 a) [235], The protocol is applicable to substrates that are sensitive to strong bases or to hydrolysis, or are difficult to extract from an aqueous phase. The procedure uses methanol as a solvent and a stoichiometric amount of potassium carbonate as a weak base. Optimum yields were obtained by heating the phenol with 1.2 equivalents of the alkyl bromide (or 3 equivalents of the less reactive chloride) at 100-140 °C for 15-30 min. 

The purpose of this review is to integrate the literature on this topic, along with some of the work we have performed, to provide a clearer understanding on the role of carbon as a deactivation mechanism. The minimization of carbon by promotion, regeneration of catalysts, and some selectivity implications will also be briefly discussed. 

With Cr(C0) , base clearly promotes the WGSR. However, unlike ruthenium carbonyl, chromium and tungsten carbonyls demonstrate less activity with trimethylamine than with carbonate as base. 

Similarly, 73-allylpalladium complexes were also employed as promoters for the cyclization.39,39a,39b The palla-dium(0)-catalyzed reaction of alkyne 168 with allylic carbonate in THF at 60 °G gave the A-allyl product 170 instead of the desired product 169. However, without isolation of 170, the reaction mixture was heated at 80 °G with 5 equiv. of K2CO3, providing 169 in 77% yield (Equation (7)). The nitrogen atom intervenes in the process as a nucleophile in the A-allylation step and as a leaving group in the cyclization step. 

Pure decarbonylation typically employs noble metal catalysts. Carbon supported palladium, in particular, is highly elfective for furan and CO formation.Typically, alkali carbonates are added as promoters for the palladium catalyst.The decarbonylation reaction can be carried out at reflux conditions in pure furfural (165 °C), which achieves continuous removal of CO and furan from the reactor. However, a continuous flow system at 159-162 °C gave the highest activity of 36 kg furan per gram of palladium with potassium carbonate added as promoter. In oxidative decarbonylation, gaseous furfural and steam is passed over a catalyst at high temperatures (300 00 °C). Typical catalysts are zinc-iron chromite or zinc-manganese chromite catalyst and furfural can be obtained in yields of... 

---