US 2015/0307354 A1Published application

Process for the coupled preparation of trisilylamine and polysilazanes having a molar mass of up to 500 g/mol

AssigneeEvonik Industries AG

InventorCarl-Friedrich HOPPE

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Abstract

The invention relates to a process for preparing trisilylamine and polysilazanes in the liquid phase, in which ammonia is introduced in a superstoichiometric amount relative to monochlorosilane which is present in an inert solvent. Here, a reaction in which trisilylamine and polysilazanes are formed proceeds. TSA is subsequently separated off in gaseous form from the product mixture. The TSA obtained is purified by filtration and distillation and obtained in high or very high purity. The bottom product mixture is conveyed from the reactor through a filter unit in which solid ammonium chloride is separated off to give a liquid mixture of polysilazanes and solvent. This is fed to a further distillation to recover solvent. As a result of the NH3 being introduced in a superstoichiometric amount relative to monochlorosilane, monochlorosilane is completely reacted in the reactor. This completely prevents the reaction of monochlorosilane with additional disilylamine formed in small amounts to form solid ammonium chloride in the downstream plant parts for purification of the TSA. The solutions filtered downstream of the reactor are accordingly completely free of solids. The distillation columns used contain no solids or deposits after conclusion of the distillation operations.

Claims8

Dependent claims

Process for preparing trisilylamine and polysilazanes in the liquid phase,

wherein
(a) at least monochlorosilane (MCS) dissolved in a solvent (L) is placed in liquid form in a reactor (1), where the solvent is inert towards monochlorosilane, ammonia, TSA, DSA and polysilazanes and has a boiling point higher than that of TSA, and
(b) the reaction is carried out in the reactor (1) by introducing ammonia (NH3) in a stoichiometric excess relative to monochlorosilane (MCS) into the reactor (1) and
(c) the reactor is depressurized, a pressure of from 0.5 bar a to 0.8 bar a is set, the product mixture (TSA, L, NH4Cl, DSA, NH3) is conveyed in gaseous form from the top of the reactor (1) through a distillation unit (2), the NH3 is separated off by means of a vacuum unit (8), the product mixture (TSA, L, NH4Cl, DSA) is condensed in a heat exchanger (7) and the product mixture (TSA, L, NH4Cl, DSA) is collected in a vessel (6),
(d) the product mixture is subsequently filtered by means of filter unit (3), with solid ammonium chloride (NH4Cl) being separated off from the product mixture, and the filtrate is conveyed from the filter unit (3) into the distillation column (4) in which DSA is separated off at the top from the mixture (TSA, L),
and the mixture (TSA, L) is fed into a distillation column (11) in which TSA is separated off at the top from the solvent (L), with the solvent being recovered, and
(e) the bottom product mixture (PS, L, NH4Cl) is conveyed from the reactor (1) through a filter unit (5) in which solid ammonium chloride (NH4Cl) is separated off, to give a mixture of polysilazanes (PS) and solvent (L) which is collected in a vessel 9, and
(f) the mixture of polysilazanes (PS) and solvent (L) is subsequently fed to a distillation column (10) in which the major part of the solvent is recovered at the top and a concentrated mixture of polysilazanes (PS) and solvent (L) is taken off from the bottom.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/345,587Filed 5 Jun 2013
Priority: DE 10 2013 209 802.227 May 2013
Published: 29 Oct 2015
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

C01B 21/087
Compounds containing nitrogen and non-metals and optionally metals: containing one or more hydrogen atoms
B01D 3/143
Fractional distillation or use of a fractionation or rectification column: by two or more of a fractionation, separation or rectification step
B01J 19/24
Chemical, physical or physico-chemical processes in general; Their relevant apparatus: stationary reactors without moving elements inside
C08G 77/62
In which all the silicon atoms are connected by linkages other than oxygen atoms: nitrogen atoms