Abstract: Disclosed is an improved method for separating impurities from a hot synthesis gas mixture which is obtained in the preparation of melamine and urea. The improved separation is achieved by use of filters made of sintered, essentially pure chromium, molybdenum, tungsten, or a mixture of any of these elements.

Abstract: The invention relates to a selective removal of impurities from the gas stream leaving a melamine synthesis reactor in the preparation of melamine from urea by means of a treatment with steam at elevated temperature in the presence of a catalyst which is shape-selective. For instance a molecular sieve is chosen.

Abstract: The invention relates to a process for the preparation of cycloalkanone and optionally cycloalkanol by causing a mixture containing cycloalkylhydroperoxide to react with cycloalkene under the influence of a catalyst, characterised in that the reaction is carried out with a short measure of cycloalkene relative to the cycloalkylhydroperoxide, under such conditions that virtually all of the cycloalkene reacts to cycloalkene oxide and optionally cycloalkanol and/or cycloalkanone, after which the mixture, optionally after decomposition of cycloalkylhydroperoxide and distillation of cycloalkane, is subjected to a first separation, in which cycloalkene oxide--and optionally other components--is separated, after which the cycloalkene oxide in the separated mixture is isomerised to substantially cycloalkanone, after which the cycloalkanone obtained--and optionally cycloalkanol--is recovered.

Abstract: The invention provides a process for the preparation of pyrimidine, 2-methyl- and/or 2-ethylpyrimidine, characterized in that for pyrimidine a nitrogen reactant, chosen from the reaction product of formamide with 1,3-diaminopropane in the liquid phase, 1-amino-3-formamidopropane, 1,4,5,6-tetrahydropyrimidine and/or 1,3-diformamidopropane, that for 2-methylpyrimidine 1-amino-3-acetamidopropane, 2-methyl-1,4,5,6-tetrahydropyrimidine and/or 1,3-diacetamidopropane, and that for 2-ethylpyrimidine 1-amino-3-propionamidopropane, 2-ethyl-1,4,5,6-tetrahydropyrimidine and/or 1,3-dipropionamidopropane is/are contacted with a palladium-containing catalyst, this being effected in the gas phase at a temperature between 200.degree. and 550.degree. C. and in the presence of a carbon monoxide-hydrogen reactant, and that pyrimidine, 2-methyl-and/or 2-ethyl-pyrimidine is recovered from the reaction mixture obtained.

Abstract: The invention relates to a process for the preparation of .alpha.-.beta. unsaturated alcohols of the formula ##STR1## where R.sub.1, R.sub.2 and R.sub.3, which may be equal or different, represent phenyl, optionally substituted with one or more alkyl and/or alkoxy groups, the total number of C atoms of these substituents being at most 5, or hydrogen or an alkyl group with 1-10 C atoms, with at least one of the groups R.sub.1, R.sub.2 and R.sub.3 representing the optionally substituted phenyl group, by hydrogenation in the liquid phase of the aldehyde corresponding with the desired alcohol, this being effected in the presence of a platinum-containing catalyst and of an alkali metal hydroxide and/or an alkali metal alkoxide as promotor, wherein platinum-on-graphite is used as catalyst.

Abstract: The process according to the invention for the preparation of a 2-propyl- or 2-butylpyrimidine, in which the corresponding 2-alkyl-1,4,5,6-tetrahydropyrimidine is dehydrogenated in the gas phase with a palladium-containing catalyst and in which a 2-propyl- or 2-butylpyrimidine is recovered from the reaction mixture, is characterized in that the gas-phase reaction is carried out using a carbon monoxide-hydrogen reactant. As this is understood a mixture of carbon monoxide and hydrogen and/or a compound capable of at least partial decomposing into CO and H.sub.2 under the reaction conditions.

Abstract: Disclosed is a process for preparing a lactam which consists essentially in the reductive amination in the gas phase of an oxoalkane carboxylic acid having the formula ##STR1## or an alkyl ester thereof, wherein R is an alkyl group having from 1 to 4 carbon atoms and n varies from 2 to 3, and wherein the reaction is carried out:A. in an atmosphere of hydrogen, andB. in the presence of a gas phase reactant selected from the group consisting of gaseous ammonia and a vaporized primary amine, andC. in the presence of a hydrogenation catalyst promoted with an alkali metal.The alkali metal particularly preferred as a promoter is sodium.

Abstract: A process is described for the catalytic gas phase reduction of 4-oxoalkanenitriles to form 2-alkylpyrroles in high yields and conversions.

Abstract: Indole, and/or methyl-substituted indoles are described as prepared from the corresponding 2-(cyanomethyl)cyclohexanone starting material through a catalytic reaction in the presence of hydrogen, using a metal, or metal compound, of Group VIII or Group Ib of the Periodic Table. The reaction is carried out at an elevated temperature at high conversion to yield the corresponding indole and (in some cases) tetra- or hexahydroindoles.

Abstract: The preparation of 5-alkyl-butyrolactones is described using C.sub.8 hydrocarbon levulinate esters, with side-chain alkyl substituents of up to 4 carbon atoms as starting material, with the reaction being conducted with hydrogen at a temperature of from 150.degree. to 325.degree. C., in the gas phase, and in the presence of a hydrogenation catalyst composed of metals of Group VIII or Group Ib of the Periodic Table. The process provides extremely high conversion rates and lactone yields, the prolonged catalyst activity.

Abstract: The process relates to hydroxylammonium salts.Cyclic process for the preparation and processing of a hydroxylammonium salt solution, in which an aqueous acid reaction medium is kept in circulation between a hydroxylammonium salt synthesis zone and an oxime synthesis zone, and in which the circulating liquid is continuously supplied with nitrogen monoxide, which serves as nitrogen source for the formation of the hydroxylammonium salt, and which is converted into hydroxylamine by catalytic reduction with hydrogen.The circulating liquid is, before it enters the hydroxylammonium salt synthesis zone, subjected to a stripping process by bringing the circulating liquid via a heat-exchanging surface in heat-exchange with nitrogen monoxide containing water vapor, upon which the water vapor condenses, and the remaining gas containing nitrogen monoxide as nitrogen source is used in the reduction of nitrogen monoxide to hydroxylamine.

Abstract: A process is described for the production of hydroxylamine, or hydroxylamine salts, from the reduction of nitrogen monoxide with hydrogen in an acid liquid reaction medium in one reactor in the presence of a noble-metal catalyst, wherein explosive gaseous mixture compositions are avoided by maintaining the presence of an inert gas at a level of between 10% and 80% by volume, and whereby the process is conducted at elevated pressures of between about 1500 and 5000 kPa.

Abstract: A process for pre-treating platinum/palladium catalysts, used in the preparation of hydroxylamine, comprising contacting the same with an aqueous salt solution, inhibits (a) the decomposition of hydroxylamine and (b) the consequent formation of explosive mixtures of N.sub.2 O with hydrogen or hydrocarbons.

Abstract: Metal electrodes are prepared by contacting a basis-metal electrode with a solution which contains an alloying element compound, said basis-metal electrode comprising a basis-metal which is present in a finely divided or porous state and is selected from the group consisting of the noble metals from the Groups IB, IIB or VIII of the Periodic Table of the Elements or an alloy of at least one of the metals, said alloying element being selected from the group consisting of an element from Groups IIIA, IVA, VA, VIA, VIII, IB, IIB, VIIB or combinations thereof of the Periodic Table of the Elements; and reducing in situ said alloying-element compound to form the free-alloying element whereby said alloying element forms an alloy with said basis-metal.

Abstract: An improved process is described for the reduction of ammonium ions, while avoiding any increase in nitrate ion concentration, in a liquid stream recycled between a zone of synthesis of hydroxyl ammonium salt and a zone for synthesis of oxime, wherein the liquid stream is contacted with a gas stream consisting essentially of nitrogen monoxide and containing nitrogen dioxide at a pressure above 1 atmosphere, at a temperature of at least 80.degree. C., such that after the contact the molar NO.sub.2 /NO ratio of the gas stream is within the range of between about 10.sup.-1 to 10.sup.-4 :1.

Abstract: Powdery alloys of two or more metals, as well as of alloys distributed in finely divided state over a carrier material, e.g., catalysts consisting of an alloy of two or more metals, are obtained by adding one of the metals as a powder or in finely divided state on a carrier to a liquid which contains a dissolved compound of the metal or dissolved compounds of the metals to be alloyed, whereupon the metal particles are treated with a reducing agent.In this way an alloy is formed without the risk for sintering of the formed alloy particles.