Nickel-copper catalysts, hydrocarbon

One of the characteristic features of the metal-catalysed reaction of acetylene with hydrogen is that, in addition to ethylene and ethane, hydrocarbons containing more than two carbon atoms are frequently observed in appreciable yields. The hydropolymerisation of acetylene over nickel—pumice catalysts was investigated in some detail by Sheridan [169] who found that, between 200 and 250°C, extensive polymerisation to yield predominantly C4 - and C6 -polymers occurred, although small amounts of all polymers up to Cn, where n > 31, were also observed. It was also shown that the polymeric products were aliphatic hydrocarbons, although subsequent studies with nickel—alumina [176] revealed that, whilst the main products were aliphatic hydrocarbons, small amounts of cyclohexene, cyclohexane and aromatic hydrocarbons were also formed. The extent of polymerisation appears to be greater with the first row metals, iron, cobalt, nickel and copper, where up to 60% of the acetylene may polymerise, than with the second and third row noble Group VIII metals. With alumina-supported noble metals, the polymerisation prod-... 

For industrial hydrogenation of vegetable and animal oils in Russia a Raney type nickel was prepared by Bag and co-workers (64). Preparation of detergents from hydrogenated fats has been reported (11). Reviews of these so-called skeleton catalysts were published by Russian investigators, for instance, by Lel chuk and co-workers (197). These catalysts have also been discussed with reference to hydrocarbon synthesis from water gas (148). Lel chuk (197) states that Raney nickel is more drastic for water gas synthesis than are the skeleton nickel catalysts prepared by Bag, and that Bag s copper-nickel skeleton catalysts approach nickel in their activity. Destructive hydrogenation under mild conditions was said to be possible with Bag s skeleton catalyst as described by Lel chuk. 

This review is followed by a consideration of some of the features characteristic of hydrocarbon reactions on catalysts comprising individual metals from Groups VIII and IB of the periodic table. Finally, the activities of a series of unsupported nickel-copper alloys for hydrogenolysis and dehydrogenation reactions are discussed. These latter studies were made to obtain information on the selectivity phenomenon with bimetallic catalysts of known structure. The nickel-copper alloys were characterized by a variety of chemical and physical probes. 

It was discovered that the ability of metals to form solid solutions (alloys) in the bulk is not necessary for a bimetallic system to be of interest as a catalyst. An example is the ruthenium-copper system, in which the two components are virtually completely immiscible in the bulk. This system exhibits an effect of the copper (in particular, selective inhibition of hydrocarbon hydrogenoly-sis) similar to that exhibited by the nickel-copper system, in which the components are completely miscible. Although ruthenium and copper do not form solid solutions in the bulk, they do exhibit a strong interaction at copper-ruthenium interfaces. The copper tends to cover the surface of the ruthenium, analogous to a chemisorbed layer. As a result, the copper has a marked effect on the chemisorption and catalytic properties of the ruthenium. 

Synthesis of Liquid Hydrocarbons by the Reduction of Carbon Mon-dxide. When carbon monoxide-hydrogen mixtures are passed over cobalt, iron, nickel, and some copper catalysts that are promoted with certain metallic oxides, particularly oxides of the alkali mietals, at temperatures in the range frmn about 200-300°C and pressures from about 1-25 atm, various hydrocarbons are formed according to the following type of reactions ... 

The relatively high cost and lack of domestic supply of noble metals has spurred considerable efforts toward the development of nonnoble metal catalysts for automobile exhaust control. A very large number of base metal oxides and mixtures of oxides have been considered, especially the transition metals, such as copper, chromium, nickel, manganese, cobalt vanadium, and iron. Particularly prominent are the copper chromites, which are mixtures of the oxides of copper and chromium, with various promoters added. These materials are active in the oxidation of CO and hydrocarbons, as well as in the reduction of NO in the presence of CO (55-59). Rare earth oxides, such as lanthanum cobaltate and lanthanum lead manganite with Perovskite structure, have been investigated for CO oxidation, but have not been tested and shown to be sufficiently active under realistic and demanding conditions (60-63). Hopcalities are out-... 

Effects of Different Metal Salicylaldimine Chelates. Varying the central metal profoundly affected catalytic and inhibitory properties. There were only small quantitative variations, however, between N-phenyl- and V-butylsalicylaldimines having the same central metal atom. The only other salicylaldimines where catalyst-inhibitor conversion could be demonstrated were those of copper (II). With copper (II) both the catalytic and the inhibitory effects are much less pronounced than for cobalt (II). Surprisingly nickel (II) complexes behaved like conventional catalysts for hydrocarbon autoxidation—i.e., the rate is proportional to... 

The catalytic reaction of steam with methane at elevated temperatures (300-400 + C) over various catalysts copper or nickel/molybde-num oxide/alumina—can be made to yield CO and H2 in desired ratios. The generalized reaction for hydrocarbons with steam is ... 

These reactions appear to cease when one equivalent of the hydrocarbon or monoxide is absorbed, so that the method seems limited to the preparation of halogen-substituted trichlorosilanes. However, the products are attractive as intermediates for the preparation of many other organosilicon compounds. No mechanism is offered for the reaction. If the salts of aluminum, copper, mercury, or nickel which are disclosed as catalysts undergo any intermediate reactions with the hydrocarbon, such reactions must be cyclic because the catalyst is not consumed. The fact that molar quantities of catalyst are required for the reaction may be evidence for such intermediate reactions. No subsequent publications on the method have appeared, and so it is difficult to evaluate its importance in comparison with the earlier syntheses. 

In 1971, Kochi reported that a catalytic silver salt induced Grignard coupling reaction with organic halides to form hydrocarbons [428,429 Eqs. (185), (186) and (187) 22,428]. However, the pair- [see Eq. (185)] and the stereoselectivity [see Eq. (187)] were not satisfactory hence, similar reactions with copper, nickel, or palladium catalysts are far more common. If a coupling reaction to be carried out involves RMgX and RX having the same R group, a silver catalyst still finds a use [Eq. (188) 430]. 

Elemental analysis of petroleum shows that the major constituents are carbon and hydrogen with smaller amounts of sulfur (0.1-8% w/w), nitrogen (0.1-1.0% w/w), and oxygen (0.1-3% w/w), and trace elements such as vanadium, nickel, iron, and copper present at the part per milHon (ppm) level. Of the non-hydrocarbon (heteroelements) elements, sulfur is the most abundant and often considered the most important by refiners. However, nitrogen and the trace metals also have deleterious effects on refinery catalysts and should not be discounted because of relative abundance. Process units with, for example, a capacity of 50,000 bbl/day that are in operation continuously can soon reflect the presence of the trace elements. The effect of oxygen, which also has an effect on refining catalysts, has received somewhat less study than the other heteroelements but remains equally important in refining. 

Oxidation in the presence of mild catalysts such as pumice or ferric oxide and at low temperatures 171 results in the acceleration of the oxidation and decomposition of the intermediate products to a greater extent than the oxidation of the hydrocarbons themselves. At high temperatures the rate of decomposition is so increased that only hydrogen and oxides of carbon are formed. Notwithstanding that the oxides of copper and nickel have been found to be too violent, they are much less so than the metals themselves. Even surface effects alone such as are produced by charcoal, pumice, brick, etc., are such that if appreciable decomposition of the hydrocarbon is to be effected, only small efficiencies toward formation of valuable compounds are obtained.47... 

The conversion of methane into formaldehyde, ethylene, and higher hydrocarbons by a process of oxidation has been claimed.1 - A mixture ot air and methane is heated in the presence ot a copper gauze catalyst under pressure to give formaldehyde, which by reaction with methane forms ethylene with removal of water in the presence of catalysts of iron, cobalt, nickel, chromium, vanadium, etc., at 500° C.—and under extremely high pressures. 

Because of the necessity for using mixtures dilute in acetylene to avoid decomposition as well as to control the temperature of the reactions, it is possible to use gases containing rather low concentrations of acetylene instead of the pure hydrocarbon. It is claimed that passage of such gases with steam over catalyst masses containing boric or phosphoric acids or the copper, nickel, or iron salts of these acids at temperatures of 200° to 300° C. results in the formation of acetaldehyde.120... 

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