Mario Marchionna

Selective synthesis of isobutanol by means of the Guerbet reaction: Part 2: Reaction of methanol/ethanol and methanol/ethanol/n-propanol mixtures over copper based/MeONa catalytic systems

The synthesis of isobutanol via the Guerbet condensation between methanol and ethanol was studied by using sodium methoxide (MeONa) as soluble basic component and copper-based catalysts as heterogeneous dehydrogenating/hydrogenating metal species. The effect of the nature of the catalyst and the relative amount of its individual components with respect to the reacting alcohols as well as of temperature on productivity and selectivity of the process was investigated. The collected data indicated that the copper chromite/MeONa was more active than Cu-Raney/MeONa system. The reaction was shown to proceed with the formation only of n-propanol and isobutanol. Ethanol conversion up to 61% with selectivity to isobutanol up to 98.4% was obtained. The same catalytic systems were also employed in the reaction of the methanol/ethanol/n-propanol ternary mixture. Again copper chromite/MeONa resulted more active than the Cu-Raney/MeONa system. Finally, experiments were carried out on methanol/n-propanol mixtures in the presence of the copper chromite/MeONa catalytic system by recycling both the recovered solid copper component and the liquid reaction mixture for evidencing eventual copper leaching by MeONa. On the basis of the obtained results it was concluded that in the Guerbet reaction copper chromite works as heterogeneous catalyst.

Light olefins dimerization to high quality gasoline components

Abstract New attractive technologies can be designed in the field of light olefins dimerization (C3–C5) in order to obtain products useful as gasoline blending components; the technologies are characterized both by low investment costs and by high product quality. Isobutene dimerization is a powerful alternative to MTBE production whenever the use of the latter will be forbidden in gasoline. Also the dimerization of iso-amylenes and propylene, when properly designed, can give products (both the olefins and the corresponding hydrogenated derivatives) characterized by very high octane numbers. More in general all these technologies can help to debottleneck the FCC downstream when enhanced olefins production is achieved by means of new FCC catalysts and processes.

Acidic and basic ion exchange resins for industrial applications

Abstract Ion exchange resins, particularly the macroporous variety, are very versatile catalysts, which play a more and more important role in the large scale manufacture of petrochemicals and solvents. Different acid and basic resins have been studied for several reactions in order to improve the catalytic performances and the process engineering with respect to current technology. Strongly basic resins were checked as catalysts for the methanol carbonylation to methyl formate. Strongly acid resins were instead employed in the isobutene dimerization to produce a mixture of ether and branched hydrocarbons, mainly C8, with high octane number.

Synthesis of isobutanol by the Guerbet condensation of methanol with n-propanol in the presence of heterogeneous and homogeneous palladium-based catalytic systems

AbstractThe catalytic synthesis of isobutanol ( i BuOH), via the Guerbet condensation of methanol with n-propanol is described.In particular, bifunctional catalysts based on either heterogeneous or homogeneous dehydrogenating/hydrogenating pal-ladium species and on sodium methoxide (MeONa) as basic component were investigated. When heterogeneous Pd/Cand MeONa was used as catalytic system a high activity was obtained with turnover numbers up to about 110mol of i BuOH/(mol of Pdh). The increase of the MeONa/Pd molar ratio increased the activity of the catalyst. However, differentlyfrom Cu-based/MeONa catalysts, a significant metal leaching was observed; recycle experiments indicated that both hetero-geneous and homogeneous palladium species are involved in the catalysis. When homogeneous palladium complexes, such astetrakis(triphenylphosphine)palladium(0) [Pd(PPh 3 ) 4 ], diphenylphosphinoethane(dichloro)palladium(II) [Pd(dppe)Cl 2 ] andbis(dibenzylideneacetone)palladium(0) [Pd(dba) 2 ], were used in combination with MeONa a remarkable activity was alsoobtained, independently of the oxidation state of the palladium precursor. During the reaction deposition of a solid was ob-served and recycle experiments carried out both on the recovered solid and on the liquid phase suggested that also in this casethe activity has to be addressed to both heterogeneous and homogeneous (or colloidal) palladium species.© 2003 Elsevier Science B.V. All rights reserved.

Selective synthesis of octadienyl and butenyl ethers via reaction of 1,3-butadiene with alcohols catalyzed by homogeneous palladium complexes

The selective synthesis, by telomerization of 1,3-butadiene with alcohols in the presence of palladium catalysts, both of octadienyl ethers (especially from higher linear primary alcohols) and of butenyl ethers is reported. The variation of the alcohol/diene molar ratio plays a decisive role in both the cases, excess of alcohol favouring in the former case the synthesis of octadienyl ethers with respect to octatrienes, being useful in the latter case, together with other factors such as high P/Pd and low Pd/diene molar ratios, to favour the formation of butenyl ethers. It has in fact been discovered that, for palladium catalysts, the formation of butenyl ethers is ruled by a complex mechanism involving both the reversible formation of butenyl ethers and their direct transformation into octadienyl ethers.

Homogeneous telomerization of 1,3-butadiene with alcohols in the presence of palladium catalysts modified by hybrid chelate ligands

Abstract 1,3-Butadiene telomerization with methanol and higher alcohols was investigated in the presence of different palladium(0) and palladium(II) complexes based on hybrid chelate ligands. When P ∩ O ligands were used, the resulting palladium complexes displayed poor activity and low selectivity to telomers, also in the presence of alkoxide promoters. Even worse performances were found when ionic palladium(II) or neutral palladium(0) and palladium(II) complexes based on N ∩ N chelate ligands were employed in combination with alkoxide promoters. Better results were obtained by using ionic palladium(II) complexes with P ∩ N ∩ N ligands in combination with an alkoxide promoter. Very promising results were achieved when the telomerization reaction was catalyzed by palladium(0) complexes obtained in situ from Pd(dba) 2 and P ∩ N ligands. The data are discussed and interpreted in terms of different capability of the chelate ligands, depending on their size and donor power, to give palladium complexes with metal sites at low oxidation state characterized at the same time by a sufficient stability and coordinative unsaturation to promote high catalytic activity and selectivity.

Mechanistic studies on the homogeneous nickel-catalyzed low temperature methanol synthesis

Abstract In situ IR monitoring of the Ni(CO)4/MeONa catalytic system for low temperature methanol synthesis has revealed the involvement of the [HNi(CO)3]− species in the catalysis. Two new methods for the synthesis of the anion were discovered and the model reactivity of [HNi(CO)3]− was also investigated. The overall results led us to suggest a catalytic cycle in which methanol is carbonylated to methyl formate with MeONa as the catalyst, while [HNi(CO)3]− catalyzes the hydrogenolysis of methyl formate to methanol.

Nickel carbonyl clusters containing interstitial carbon-congener atoms: synthesis and structural characterisation of the [Ni12(µ12-E)(CO)22]2–(E = Ge, Sn) and [Ni10(µ10-Ge)(CO)20]2– dianions

The first example of carbonyl clusters containing fully interstitial germanium and tin atoms have been isolated from the reaction of their chlorides with [Ni6(CO)12]2–; the structures of the icosahedral [Ni12Ge(CO)22]2– and [Ni12Sn(CO)22]2– and the pentagonal antiprismatic [Ni10Ge(CO)20]2– have been established from X-ray diffraction studies.

Hydroformylation of Z-2-butene with the PtCl2(cod)/SnCl2/L catalytic system: Part 3. The effect of the phosphorus ligand L☆

Abstract In a study on the hydroformylation of the internal olefln, 2-butene, with the catalytic system PtCl2(cod)/SnCl2 in the presence of a phosphorus ligand L, the ligand has been varied in an attempt to achieve high selectivities with respect to the linear aldehyde, n-pentanal. Forty ligands were examined and the catalytic results are discussed in terms of steric and electronic parameters. When the ligand is not too bulky, the reactivity is determined solely by the electronic parameter. Very promising results were obtained with aryl phosphites as the phosphorus ligands; selectivities in n-pentanal of 65–75% have been achieved, along with a high activity of the catalytic system. The proportion of hydrogenation is relatively low (5–10%). A considerable disadvantage with this catalytic system is the instability of phosphite ligands under the reaction conditions; however, use of cyclic phosphites has been found to enhance the stability of the system.

Hydrogenation of organic substrates by an heterogenized catalyst based on a bis(diphenylphosphino)methane polymer-bound palladium(II) complex

Abstract Pd(OAc) 2 undergoes easy and quantitative coordination to a cross-linked styrene/divinylbenzene resin functionalized with bis(diphenylphosphino)methane ligands to yield a supported palladium complex which behaves as a versatile and recyclable heterogenized catalyst for the hydrogenation of nitrocompounds and α,β-unsaturated aldehydes under mild conditions. Whereas nitrobenzene is converted only into aniline, cinnamaldehyde is selectively converted into hydrocinnamaldehyde.