Huels Aktiengesellschaft

Veba-Chemie Aktiengesellschaft

Gerd Bohmholdt

Hans-Werner Michalczak

Peter Kirchner

Josef Disteldorf

Wilhelm Heitmann

Wilhelm Huwels

Gunter Deininger

Winfried Hahn

Helmut Riedel

Hans-Otto Gerlach

Hinrich Husemann

A continuous multistage process for the preparation of (cyclo)aliphatic diisocyanates comprising a) condensing urea with a (cyclo)aliphatic diamine in the presence of an alcohol solvent to make a (cyclo)alkylenebisurea in a distillation reactor; b) reacting the crude (cyclo)alkylenebisurea with alcohol in a pressurized distillation reactor to make (cyclo)biscarbamate; c) removing the ammonia formed in the pressurized distillation reactor; d) cleaving the (cyclo)biscarbamate in the presence of a catalyst in a combined cleavage and rectifying column to make crude (cyclo)alkylene diisocyanate; e) reacting a diverted portion of the cleavage products with the alcohol to form a recycling mixture; f) and distilling the crude (cyclo)alkylene diisocyanate formed in step d.

Continuous multi-stage process for the preparation of (cyclo) aliphatic

A circulation process for the production of (cyclo)aliphatic diisocyanates, in which the biscarbamate is produced from diamines, by-products from the thermal cracking, urea, and alcohol in the presence of N-unsubstituted carbamates and dialkyl carbonates, and with separation of NH.sub.3 ; the subsequent cracking of the biscarbamate is carried out in the liquid phase without solvent; the diisocyanate and alcohol are condensed; the diisocyanate is subjected to a purifying distillation; and a portion of the cracking reaction mixture is discharged with the by-products formed and recycled to the biscarbamate production step after prior reaction with the crude alcohol formed, effectively utilizes the by-products formed in the cracking step and is an industrially practical and economical process.

Circulation process for the production of aliphatic and cycloaliphatic

A process for the purification of pressurized gases, such as those emanating from the partial gasification resp. combustion of fuel, which gases contain Ni(CO).sub.4, which comprises contacting said Ni(O).sub.4 containing gas with a solvent at a temperature of from -60 to 0.degree. C., thereby forming a solution containing the gases and dissolved Ni(CO).sub.4, and thereafter heating said solution at a temperature of from 70 to 250.degree. C. for at least 0.25 hour at a pressure higher than the vapor pressure of said solvent, thereby precipitating and thereafter recovering nickel compound and releasing a purified solvent.

Process for the purification of scrubbing solvents by removal of Ni(CO).sub

In the process of making ketones by oxidizing olefins wherein olefins are first hydrated to secondary alcohols which are then dehydrogenated to ketones, the hydration step is carried out simultaneously with a liquid organic extraction step during which the secondary alcohols and ether by-product formed are absorbed and, following separation of the olefin-water phase, the secondary alcohols in the organic extracted phase are dehydrogenated and the ether by-product is purged.

Process for producing ketones

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Marl-Polsum, Germany

Gerd Bohmholdt