Abstract: Hydrogen sulfide is oxidized to sulfur by means of treatment with an aqueous acid solution containing trivalent iron and a hetero polyacid having formula (I): HnXVyM(12-y)O40; or a sole hetero polyacid having formula (II): HnMeM12O40; wherein the symbols X, M Me n and y are specified in the text. At the end of the oxidation, the solution is treated with gas containing oxygen to re-oxidize the reduced metal.

Abstract: The present invention relates to solid base catalysts consisting of an amorphous material obtained from a silica or alumina gel containing an alkaline, earth-alkaline or transition metal (M), characterized by a molar ratio between metal (M) and Si or Al ranging from 30:1 to 0.0001:1, a surface area ranging from 100 to 600 m2/g, an overall pore volume ranging from 0.1 to 1.1 ml/g, an average channel diameter ranging from 30 to 150 ? and a density of the base sites ranging from 10 to 900 ?mol/g. Said catalysts can be conveniently used in base catalysis reactions.

Abstract: Hydrogen sulfide is oxidized to sulfur by means of treatment with an aqueous acid solution containing trivalent iron and a hetero polyacid having formula (I): HnXVyM(12-y)O40; or a sole hetero polyacid having formula (II): HnMeM12O40; wherein the symbols X, M Me n and y are specified in the text. At the end of the oxidation, the solution is treated with gas containing oxygen to re-oxidize the reduced metal.

Abstract: Process for the production of concentrated aqueous solutions of hydrogen peroxide, comprising the following steps: (a) feeding to a reactor containing a catalyst based on palladium and platinum, heterogeneous and maintained in dispersion in a liquid reaction medium: (i) a liquid stream consisting of an alcohol or a mixture of C1–C3 alcohols or a mixture of said alcohols with water containing at least 50% by weight of alcohol, also containing an acid promoter and a halogenated promoter, the alcohol and optionally all or part of the water contained in the stream being recycled from the subsequent phase d); (ii) a gaseous stream containing hydrogen, oxygen and an inert gas, characterized in that the concentration of the hydrogen is less than 4.

Abstract: Integrated process for the preparation of aromatic isocyanates comprising: the reaction between an aromatic amine and an organiccarbonate in the presence of a catalyst selected from organic and inorganic salts of a metal selected from Zn, Sn, Pb, Cu; the removal of the catalyst; the passivation of the quantity of residual metal in the urethane formed in step a); the removal of the organic solvent and its optional recycling to step a) of the reaction; the evaporation of the aromatic urethane with partial pyrolysis; the complete pyrolysis of the urethane in gas phase; the recovery of the isocyanate.

Abstract: Process for the production of concentrated aqueous solutions of hydrogen peroxide, comprising the following steps: (a) feeding to a reactor containing a catalyst based on palladium and platinum, heterogeneous and maintained in dispersion in a liquid reaction medium: (i) a liquid stream consisting of an alcohol or a mixture of C1-C3 alcohols or a mixture of said alcohols with water containing at least 50% by weight of alcohol, also containing an acid promoter and a halogenated promoter, the alcohol and optionally all or part of the water contained in the stream being recycled from the subsequent phase d); (ii) a gaseous stream containing hydrogen, oxygen and an inert gas, characterized in that the concentration of the hydrogen is less than 4.

Abstract: The present invention relates to solid base catalysts consisting of an amorphous material obtained from a silica or alumina gel containing an alkaline, earth-alkaline or transition metal (M), characterized by a molar ratio between metal (M) and Si or Al ranging from 30:1 to 0.0001:1, a surface area ranging from 100 to 600 m2/g, an overall pore volume ranging from 0.1 to 1.1 ml/g, an average channel diameter ranging from 30 to 150 Å and a density of the base sites ranging from 10 to 900 &mgr;mol/g. Said catalysts can be conveniently used in base catalysis reactions.

Abstract: Integrated process for the preparation of aromatic isocyanates comprising: the reaction between an aromatic amine and an organiccarbonate in the presence of a catalyst selected from organic and inorganic salts of a metal selected from Zn, Sn, Pb, Cu; the removal of the catalyst; the passivation of the quantity of residual metal in the urethane formed in step a); the removal of the organic solvent and its optional recycling to step a) of the reaction; the evaporation of the aromatic urethane with partial pyrolysis; the complete pyrolysis of the urethane in gas phase; the recovery of the isocyanate.

Abstract: A liquid composition, polymerizable by means of a free-radical route to yield optical articles endowed with a high refractive index, contains an allyl-carbonate derivative definable with the general formula: (wherein R1, X1, X2, X3, X4, X5, X6, a and b are as defined in the disclosure) and a copolymerizable monomer containing at least one ethylenic unsaturation in its molecule.

Abstract: The present invention relates to a continuous process for the preparation of phenyl methyl carbonate. The process is carried out in a first distillation column consisting of a lower reactive section and an upper rectification section and a second rectification column. The reactive section of the first column has a practically constant thermal profile at the optimum temperature for the reaction, and that with the use of the second column a circulation of dimethyl carbonate is created between the top and bottom of the first column which allows an advantageous excess of dimethylcarbonate to be fed to the bottom of the first column.

Abstract: Dialkyl carbonate is prepared by reacting an alcohol with a gaseous mixture of carbon monoxide and oxygen in the presence of cuprous chloride as catalyst and hydrochloric acid as in situ regenerator of the catalyst.

Abstract: A method is described enabling HCl and possible entrained CuCl particulate to be removed from a gas-vapor stream leaving a dimethylcarbonate synthesis reactor. The contaminant removal is effected by one of the process fluids used in a small quantity.

Abstract: A carbonate ester of an aliphatic triol or tetraol which can be defined with the following formula: ##STR1## wherein R.sub.1, R.sub.2, R' and p are as defined in the description, is used as a lubricating base with a low quantity of smoke for two-phase engines with internal combustion.Lubricating compositions are described which contain a carbonate ester (1) together with one or more products selected from solvents, bright stock, or other anti-seizing additives, plus normal additives.

Abstract: Zeolites having a pore diameter comprised within the range of from 5 to 12 .ANG. are bonded with amorphous oligomeric silica, by dispersing them in an aqueous solution of silica and alkylammonium hydroxide, and submitting the obtained suspension to a quick drying.

Abstract: Catalytic procedure for the preparation of an organic carbonate having general formula (I): ##STR1## wherein R represents a C.sub.1 -C.sub.10 alkyl radical, linear or branched, or a C.sub.5 -C.sub.8 cycloalkyl radical; or of a cyclic organic carbonate having general formula (II): ##STR2## wherein R' represents a C.sub.2 -C.sub.5 alkylene radical, linear or branched; including the reacting of an aliphatic or cyclo-aliphatic alcohol having general formula (III):R--OH (III)or an aliphatic diol having general formula (IV):HO--R'--OH (IV)wherein R and R' have the meaning described above, with carbon monoxide and oxygen, in the presence of a catalyst composed of a cobalt(II) or cobalt(III) ion and an organic binder containing at least one oxygen atom, characterized in that the process is carried out in the presence of at least one reaction coadjuvant selected from the following groups of linear or cyclic compounds: ureas, nitriles, amides, phosphoramides, sulphones, sulphoxides, carbamates.

Abstract: Organic carbonates and cyclic organic carbonates are prepared by reacting an aliphatic or cycloaliphatic alcohol, or, respectively, an aliphatic diol, with carbon monoxide and oxygen, by operating in the presence of a complex catalyst of cobalt with organic ligands bearing one or more oxygen functional groups, as electron donors.

Abstract: Multistep process for the preparation of alkyl mono and diisocyanates consisting in reacting the corresponding aliphatic amine or diamine with dimethylcarbonate and, substantially, in partially vaporizing and converting the urethane thus formed in an evaporator to subsequently terminate the cracking in a II.degree. reactor, and finally subjecting the cracking product to fractional distillation at reduced pressure, recycling the unconverted part to the partial vaporization step.

Abstract: A liquid composition, polymerizable by free-radical polymerization to yield organic glasses which are endowed with characteristics of low water absorption and high thermal stability, is constituted by the product of transesterification of diallyl-carbonate with a cycloaliphatic diol or a mixture of cycloaliphatic diols, from among said diols 1,4-cyclohexane-di-methanol and 3(4),8(9)-bis-(hydroxymethyl)tricyclo[5.2.1.0.sup.2.6 ]decane being preferred.

Abstract: Process for the preparation of 4,4'-diaminodiphenylmethane and its derivatives.4,4'-diaminodiphenylmethane and its derivatives are prepared by the condensation of aniline, or its derivative, and aldehyde, or its precursor and/or isomerization of appropriate intermediate products. The reaction proceeds with zeolites acting as catalysts; these catalysts, which are selected in accordance with the reaction to be effected, are preferably zeolites based on Si, Al and B; Si, Al and Ti; Ti and Fe; ZSM-5; or Y zeolites.

Abstract: A process is described for preparing a di-alkyl carbonate, e.g. dimethylcarbonate, via oxidative carbonylation of the corresponding alkanol, e.g. methanol, in the presence of a catalyst system which comprises a copper alkoxy-halide and a quantity of between 0.5 and 10 mol % of C.sub.u X.sub.2 or HX with respect to the total moles of copper. In this manner extremely high di-alkyl carbonate formation rates are obtained.