Catalyst alcohol synthesis

Isobutyl alcohol [78-83-1] forms a substantial fraction of the butanols produced by higher alcohol synthesis over modified copper—zinc oxide-based catalysts. Conceivably, separation of this alcohol and dehydration affords an alternative route to isobutjiene [115-11 -7] for methyl /-butyl ether [1624-04-4] (MTBE) production. MTBE is a rapidly growing constituent of reformulated gasoline, but its growth is likely to be limited by available suppHes of isobutylene. Thus higher alcohol synthesis provides a process capable of supplying all of the raw materials required for manufacture of this key fuel oxygenate (24) (see Ethers). 

For this alcohol synthesis stoichiometric amounts of aluminum alkyls are required. Beside the wanted fatty alcohols high-purity aluminum oxide is formed. This aluminum oxide is of high value, e.g., for the production of catalysts and improves the economy of the Alfol process. 

Bradshaw, C.W., Hummel, W. and Wong, C.H. (1992) Lactobacillus kefir alcohol dehydrogenase a useful catalyst for synthesis. The Journal of Organic Chemistry, 57 (5), 1532—1536. 

Leclercq, L., Almazouari, A., Dufour, M., and Leclercq, G. 1996. Carbide-oxide interactions in bulk and supported tungsten carbide catalysts for alcohol synthesis. In Chemistry of transition metal carbides and nitrides, ed. S. T. Oyama, 345-61. Glasgow Blackie. 

This new hydrogenation procedure is clean, mild, and effective. It offers a very practical method for chiral alcohol synthesis. Isolated Ru complexes are fairly air and moisture stable and can be stored in an ordinary vial for quite a long time. Compared with the catalysts prepared in situ, the reaction rates in the asymmetric hydrogenations catalyzed by 70 are higher by two orders of magnitude. 

In CO hydrogenation, the achvity and selechvity to C1-C5 oxygenates over the bimetallic samples are higher than those of the monometallic counterparts [187-190]. Bimetallic catalysts also showed improved activity in the hydroformylation of ethylene compared to either of the monometallic catalysts [191]. The promotion for higher alcohol production is proposed to be associated with the adjacent Ru-Co sites. However, the lack of an exhaustive characterization of catalysts does not allow a clear correlation to be established between the characteristics of the active sites and the catalytic behavior. A formyl species bonded to a Ru-Co bimetallic site has been proposed to be the intermediate in the alcohol synthesis in these systems. A subsequent reaction with an alkyl-surface group would lead to the C2-oxygenate production [187]. 

I.F.P. (France) and Idemitsu Kosan (Japan), as a member of RAP AD (Research Association for Petroleum Alternative Development), are involved in process and catalysts development for alcohols synthesis. This paper details most of our recent results. 

TABLE II METHAWOL-HIGHER ALCOHOLS SYNTHESIS ON COPPER-COBALT BASED CATALYSTS... 

C 0 and H O, unavoidable by-products of alcohols synthesis. Considering chemical reactions of table H, water and carbon dioxide appear as equiva-lentby-products due to shift conversion equilibrium, equation (1). Most other low temperature alcohol synthesis catalysts have a rather high shift activity as well. CO removal fhom reacted syngas of synthesis loop, before recycling to reactor, leads to a significant decrease of water formation which, in turn, results in a lower water content in the raw alcohols, leading to simplified fhactionation-dehydration processes. 

Alcohol Synthesis from Carbon Oxides and Hydrogen on Palladium and Rhodium Catalysts... 

Esters are common components in cosmetics and skin-care products. They can be synthesized from fatty acids and alcohols using either chemical or enzymatic reactions. The chemical reactions are normally catalysed by acid catalysts. Enzymatic synthesis is carried out under milder conditions and therefore it provides products of very high purity. A range of esters such as isopropyl palmitate and isopropyl myristate are now produced industrially using enzymatic synthesis. The reactions are carried out in solvent-free systems using an immobilised lipase as catalyst. In order to get high yields in the reactions, water is removed continuously. 

Advances in higher alcohol synthesis that need to be made include improving productivity and selectivity. Higher spacetime yields are also required which may be achieved by dual catalyst bed reactors, the use of slurry phase synthesis process to increase CO conversion levels, and injection of lower alcohols into the reactant stream to increase the rate of higher alcohol formation.630... 

R—MgX R—Li 1 R—C—OMgX 1 R—C—OLi ether solvent, no catalyst needed synthesis of alcohols, Section 14-12A... 

Primary alcohols of n-carbon atoms are readily converted to symmetrical ketones of 2n — 1 carbon atoms by vapor-phase contact with various catalysts. A synthesis involving a Tischenko condensation (1) is a variation of an ester synthesis used commercially in Russia (2). In the conversion of ethyl alcohol to acetone by reaction with steam, ethylacetate is considered an important intermediate in the chain of reactions involved. 

Applications of HT-type catalysts, prepared by the above methods, have been reported in recent years for basic catalysis (polymerization of alkene oxides, aldol condensation), steam reforming of methane or naphtha, CO hydrogenation as in methanol and higher-alcohol synthesis, conversion of syngas to alkanes and alkenes, hydrogenation of nitrobenzene, oxidation reactions, and as a support for Ziegler-Natta catalysts (Table 2). 

Hu and co-workers have developed an expert system especially for the optimization of higher alcohol synthesis catalysts [27, 28]. The knowledge base contains data about experimental work and heuristic rules about... 

Appropriate catalysts are necessary for all fuel and chemical synthesis. The basic concept of a catalytic reaction is that reactants adsorb onto the catalyst surface and rearrange and combine into products that desorb from the surface. One of the fundamental functional differences between various syngas synthesis catalysts is whether the adsorbed CO molecule dissociates on the catalyst surface. For FTS and higher alcohol synthesis, CO dissociation is a necessary reaction condition. For methanol... 

Three commercial homogeneous catalytic processes for the hydroformyla-tion reaction deserve a comparative study. Two of these involve the use of cobalt complexes as catalysts. In the old process a cobalt salt was used. In the modihed current version, a cobalt salt plus a tertiary phosphine are used as the catalyst precursors. The third process uses a rhodium salt with a tertiary phosphine as the catalyst precursor. Ruhrchemie/Rhone-Poulenc, Mitsubishi-Kasei, Union Carbide, and Celanese use the rhodium-based hydroformylation process. The phosphine-modihed cobalt-based system was developed by Shell specih-cally for linear alcohol synthesis (see Section 7.4.1). The old unmodihed cobalt process is of interest mainly for comparison. Some of the process parameters are compared in Table 5.1. 

Rare earth oxides are useful for partial oxidation of natural gas to ethane and ethylene. Samarium oxide doped with alkali metal halides is the most effective catalyst for producing predominantly ethylene. In syngas chemistry, addition of rare earths has proven to be useful to catalyst activity and selectivity. Formerly thorium oxide was used in the Fisher-Tropsch process. Recently ruthenium supported on rare earth oxides was found selective for lower olefin production. Also praseodymium-iron/alumina catalysts produce hydrocarbons in the middle distillate range. Further unusual catalytic properties have been found for lanthanide intermetallics like CeCo2, CeNi2, ThNis- Rare earth compounds (Ce, La) are effective promoters in alcohol synthesis, steam reforming of hydrocarbons, alcohol carbonylation and selective oxidation of olefins. 

Usually not considered as Fischct-Tropsch processes are the methanol synthesis with oxidic chromium/zinc catalysts (c.f. the chapter on Methanol Building Block for Chemicals ) or the higli-pressure-high-temperature synthesis of higher alcohols over alkalized methanol catalysts or thorium catalysts (isobutyl synthesis). Tliese reactions, as well as the methanation reactions, are not covered in this contribution. 

The effectiveness of this secondary reaction K, Fig. 1) depends on the ratio of hydroformylation and readsorption rate constants (j8a/j8r). The effect of intrapellet transport restrictions on alcohol selectivity is shown in Fig. 26a for j8a/j8r = 0.5. These results were obtained for a catalyst with kinetic parameters identical to those used to describe selectivity data on Co catalysts in Figs. 16, 17, and 19. Not surprisingly, transport-limited pellets favor these secondary hydroformylation reactions and alcohol selectivity increases with increasing values of the Thiele modulus (Fig. 26a, curve A). Clearly, olefin hydroformylation pathways are most effective when they compete locally with readsorption and chain initiation at high intrapellet olefin fugacities within transport-limited FT synthesis pellets. Outside pellets, hydroformylation sites use only those few olefins that exit FT catalyst pellets after extensive readsorption and chain initiation (Fig. 26a, curve B). Hydroformylation reactions on these external sites occur at much lower rates, which simply reflect the lower olefin fugacities in the gas phase as a result, such extrapellet sites affect FT and alcohol synthesis selectivity only slightly. 

Performances of each catalyst is shown in Figure 1. The ethanol synthesis catalyst (Fe-based catalyst. Cat. 1) have both functions of F-T synthesis and alcohol synthesis. The main products were hydrocarbons, ethanol and methanol. With the increase of CO in reaction gas, the yield of ethanol increased[l]. The Cu-based catalyst (Cat. 2) converted CO2 to CO with selectivity more than 70% at a temperature range from 270 to 370°C, and other products were methanol and a slight amount of methane. Ethanol and C2 hydrocarbons were not produced. In order to harmonize the three functions, C-C bond growth, partial reduction of CO2 to CO, and OH insertion to products, the mixed ratio of Fe-based catalyst to Cu-based catalyst was coordinated at the range from Cu/Fe =... 

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