摘要:
Aromatic amines are produced by catalytic hydrogenation of corresponding aromatic nitro compounds in the gas phase, by carrying out the hydrogenation in the presence of catalysts which, besides palladium, vanadium and lead, contain in addition molybdenum, tungsten and/or rhenium on a ceramic support having a BET surface area of less than 40 m.sup.3 /g, at temperatures of from 180.degree. C. to 500.degree. C. in a catalyst bed and in a molar ratio of hydrogen to the nitro group or nitro groups of 3:1 to 30:1.
摘要:
Isocyanates or isocyanate mixtures which contain no appreciable amounts of color causing materials are produced by phosgenating the amine corresponding to the desired isocyanate and treating the isocyanate-containing phosgenation mixture with hydrogen in the presence of a supported catalyst. The supported catalyst is in a form such that its shortest dimension is from about 0.3 to about 3.0 mm. This catalyst has a BET surface of from about 0.5 to about 150 m.sup.2 /g. No alkali material can be present in the catalyst. These isocyanates are particularly useful for the production of light-colored foams.
摘要:
Azomethines can be prepared by the condensation of cycloalkanones and anilines in the presence of acid heterogeneous catalysts, with azeotropic removal of the water of reaction, the condensation being carried out in a continuous reaction in a column-like reactor having an applied temperature profile, and the starting materials being fed in the low-temperature zone and, of the reaction products, the water of reaction to be removed as an azeotrope also being removed in the low-temperature zone and the azomethine formed being removed in the high-temperature zone.
摘要:
Dialkyl carbonates can be prepared in a continuous manner by transesterification of ethylene carbonate or propylene carbonate with alcohols in the presence of a catalyst in a column equipped with packing or baffles, by passing the reactants in countercurrent such that the ethylene carbonate or propylene carbonate are metered into the upper part of the column and the alcohol is metered into the lower part of the column and the catalyst is arranged as a fixed bed in the column or is also metered into the upper part of the column in solution or suspension, the dialkyl carbonate formed, if appropriate as a mixture with alcohol, being removed at the top of the column and the ethylene glycol or propylene glycol formed from the ethylene carbonate or propylene carbonate being removed at the foot of the column, if appropriate together with the catalyst.
摘要:
Aromatic amines are produced by hydrogenation of the associated aromatic nitro compounds in the gas phase over fixed catalysts. The catalysts contain active hydrogenation metals on supports. The reaction is conducted at a pressure of 2-50 bar and at a temperature in the range 250.degree.-500.degree. C. under adiabatic conditions. A circulating gas is passed over the catalyst, which circulating gas contains 3-150 moles of hydrogen, 2-100 moles of the amino groups to be formed per mole of nitro groups, and 2 to 6 moles of water per amino group equivalent. The amine and water formed, as well as a purification stream, are separated from the circulating gas. Thereafter the circulating gas is enriched with volatilised aromatic nitro compound and fresh hydrogen and recycled.
摘要:
The present invention relates to a process for the preparation of aliphatic oligocarbonate diols bya) transesterifying dimethyl carbonate with aliphatic diols in the presence of soluble transesterification catalysts in a gas-liquid countercurrent apparatus to form oligocarbonates until the degree of conversion of the initial dimethyl carbonate is more than 80% andb) removing methanol and traces of dimethyl carbonate in an apparatus which generates gas bubbles in the oligocarbonates until the degree of capping of the terminal OH groups with methoxycarbonyl groups is less than 5%.
摘要:
Aromatic amines are produced by catalytic hydrogenation of nitroaromatic compounds in the gas phase. The catalyst includes palladium and lead on graphite or on a graphite-containing coke support. From 30 to 6000 equivalents of hydrogen for each equivalent of nitro groups are contacted with the catalyst during this process.
摘要:
A method for preparing a chloroethylglucopyranose which comprisesa) reacting glucose with from 2 to 10 times the molar amount of chloroethanol at from 100.degree. to 130.degree. C. in the absence of a catalyst, optionally removing water,b) further reacting the product of step (a) at 60.degree. to 90.degree. C. in the presence of an acidic catalyst for from 10 to 600 minutes andc) Separating therefrom the chloroethylglucopyranose.
摘要:
Di-(C.sub.1 -C.sub.4 -alkyl) carbonates can be prepared by catalysed counter-current reesterification of ethylene glycol carbonate or propylene glycol carbonate with a C.sub.1 -C.sub.4 -alcohol in a column, ethylene glycol carbonate or propylene glycol carbonate being introduced into the upper part of the column and a dialkyl carbonate-containing C.sub.1 -C.sub.4 -alcohol being introduced into the central or lower part of the column and pure alcohol being additionally introduced below the introduction of the dialkyl carbonate-containing alcohol.