Copper promoted catalyst

The catalysts were evaluated by exposure to a simulated automobile exhaust gas stream composed of 0.2% isopentane, 2% carbon monoxide, 4% oxygen and a balance of nitrogen. The temperature required to oxidize the isopentane and carbon monoxide was used to compare catalyst performance. The chromium-promoted catalyst oxidized isopentane at the lowest temperature, and a mixed chromium/copper-promoted catalyst proved the most efficient for oxidizing carbon monoxide and isopentane. It is interesting to note that the test rig used a stationary engine with 21 pounds of catalyst. Although the catalyst was very effective it is difficult to envisage uranium oxide catalysts employed for emission control of mobile sources. 

It has been shown by Bjorklund et al. [84] that vanadia on Ti02/Si02 catalysts are promoted by iron and copper. Iron-promoted catalysts showed the highest activities compared to copper-promoted and nonpromoted catalysts. The activity increased from 92% NO conversion up to 97% after 200 h on stream. Introducing SO2 into the gas resulted in an increase of activity for the iron-promoted catalyst and a rapid decrease of activity for the copper-promoted catalyst. 

Manufacture. Furfuryl alcohol has been manufactured on an industrial scale by employing both Hquid-phase and vapor-phase hydrogenation of furfural (56,57). Copper-based catalysts are preferred because they are selective and do not promote hydrogenation of the ring. 

High pressure processes P > 150 atm) are catalyzed by copper chromite catalysts. The most widely used process, however, is the low pressure methanol process that is conducted at 503—523 K, 5—10 MPa (50—100 atm), space velocities of 20, 000-60,000 h , and H2-to-CO ratios of 3. The reaction is catalyzed by a copper—zinc oxide catalyst using promoters such as alumina (31,32). This catalyst is more easily poisoned than the older copper chromite catalysts and requites the use of sulfiir-free synthesis gas. 

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. 

GP 6] [R 5] With a stabilized CU2O catalyst layer, by addition of bromomethane (ppm level), 20% selectivity at 5% conversion was found (0.5 vol.-% propene 0.1 vol.-% oxygen 2.25 ppm promoter 350 °C) [37]. This is far better than with non-conditioned copper oxide catalysts which contain CuO besides CU2O. It is expected that the first species promotes more total oxidation, whereas the latter steers partial oxidation. In the above experiment, selectivity rises from 7 to 30% at slightly reduced conversion after 3 h of promoter conditioning. 

Park PW, Ledford JS (1998) The influence of surface structure on the catalytic activity of cerium promoted copper oxide catalysts on alumina oxidation of carbon monoxide and methane. Catal Lett 50(1—2) 41 48... 

Cu(OTf)2 generally gives yields intermediate between those of the other two catalysts, but with a closer resemblance to rhodium. In competition experiments, the better coordinating norbomene is preferred over styrene, just as in the case with Pd(OAc)2. Cu(acac)2, however, parallels Rh2(OAc)4 in its preference for styrene. These findings illustrate the variability of copper-promoted cyclopropanations, and it was suggested that in the Cu(OTf)2-catalyzed reactions of diazoesters, basic by-products, which are formed as the reaction proceeds, may gradually suppress... 

In an intramolecular version of ketocarbenoid a-C/H insertion, copper-promoted decomposition of l-diazo-3-(pyrrol-l-yl)-2-propanone (258a) or l-diazo-4-(pyrrol-l-yl)-2-butanone (258b) resulted in quantitative formation of the respective cycli-zation product 259 242 >. The cyclization 260 -> 261, on the other hand, is a low-yield reaction which is accompanied by olefin formation. The product ratio was found to vary with the copper catalyst used, but the total yield never exceeded 35 % 243>. 

Soled S.L., Iglesia E., and Fiato R.A. 1992. Copper-promoted cobalt manganese spinel catalyst and method for making the catalyst for Fischer-Tropsch synthesis. U.S. Patent 5162284. 

Mukaiyama Michael reactions of alkylidene malonates and enolsilanes have also been examined (244). The stoichiometric reaction between enolsilane (342a) and alkylidene malonate (383) proceeds in high selectivity however, catalyst turnover is not observed under these conditions. The addition of HFIP effectively promotes catalyst turnover, presumably by protonation and silyl transfer from the putative copper malonyl enolate generated in this reaction. The reaction proved general for bulky P-substituents (aryl, branched alkyl), Eq. 209. 

Promoted skeletal copper was also imaged with the FIB. In particular, both zinc- and chromium-promoted skeletal copper have a structure similar to that of un-promoted skeletal copper, but on a much finer scale [110,111], This observation agrees with the increased measured surface areas for these promoted catalysts. Figure 5.2a shows the fine uniform ligaments in a zinc-promoted skeletal copper catalyst. 

Catalyst systems for the WGS reaction that have recently received significant attention are the cerium oxides, mostly loaded with noble metals, especially platinum 42—46]. Jacobs et al. [44] even claim that it is probable that promoted ceria catalysts with the right development should realize higher CO conversions than the commercial Cu0-Zn0-Al203 catalysts. Ceria doped with transition metals such as Ni, Cu, Fe, and Co are also very interesting catalysts 37,43—471, especially the copper-ceria catalysts that have been found to perform excellently in the WGS reaction, as reported by Li et al. [37], They have found that the copper-ceria catalysts are more stable than other Cu-based LT WGS catalysts and at least as active as the precious metal-ceria catalysts. 

Adjustment of the C0 H2 ratio is effected by the shift reaction (iv) which proceeds over a chromium-promoted iron catalyst at 700-800°F (370-425°C) or over a reduced copper/zinc catalyst at 375" 50°F (190-230 C) and the fraction of crude gas sent through the shift reactor is calculated from the initial gas composition and specific downstream requirements. The latter are i1 lustrated by... 

In certain cases, when the palladium or nickel catalyzed coupling is not efficient or fails completely, an alternate solution is provided by the use of copper based catalyst systems. The 5-iodouracil derivative shown in 7.77. was unreactive towards imidazole using either the Buchwald-Hartwig conditions or the copper(I) triflate promoted the carbon-nitrogen bond formation reported by Buchwald98 These latter conditions, however, were effective in coupling the iodouracil with a series of other amines (7.77.), The optimal catalyst system consisted of copper(I) triflate, phenantroline and dibenzylideneacetone (dba).99... 

The scope of the copper promoted nucleophilic displacement reactions on heterocyclic systems is not limited to nitrogen, oxygen and phosphorous nucleophiles. Buchwald and co-workers demonstrated that the same catalyst system that is efficient in carbon-phosphorous bond formation is also the... 

We have developed a multimetallic catalyst for the large scale synthesis of sterically hindered mono-N-alkylanilines with very good selectivity and high catalytic activity. In contrast to copper chromite catalysts which allow the N-alkylation only with primary alcohols, the doubly promoted Pt/Si02 catalysts described here are useful for the reaction of ortho-substituted anilines with both primary and secondary alcohols. 

Experiments with catalysts which are known to catalyze the alkylation reaction in the liquid phase (ref. 3), showed that the desired gas-phase reaction of substituted anilines with alkoxy-alcohols occurs, but with very low yield. Pd promoted copper chromite catalysts which are able to catalyze the alkylations of sterically hindered anilines with primary alkoxyalcohols (ref. 4, 5) showed only very low activity and selectivity when secondary alcohols were used. 

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