Abstract:
In a process for preparing phthalic anhydride by passing a gas stream comprising o-xylene, oxygen and sulfur dioxide at elevated temperature over a catalyst comprising heavy metals, the content of N-acyl compounds in the gas stream is restricted to less than 200 ppm, based on the weight of o-xylene.
Abstract:
A process for catalytic hydrogenation of adiponitrile to hexamethylenediamine at elevated temperature and elevated pressure in the presence of catalysts based on elemental iron as catalytically active component and ammonia as solvent comprises a) hydrogenating adiponitrile at from 70 to 220° C. and from 100 to 400 bar in the presence of catalysts based on elemental iron as catalytically active component and ammonia as solvent to obtain a mixture comprising adiponitrile, 6-aminocapronitrile, hexamethylenediamine and high boilers until the sum total of the 6-aminocapronitrile concentration and the adiponitrile concentration is within the range from 1 to 50% by weight, based on the ammonia-free hydrogenation mixture, b) removing ammonia from the hydrogenation effluent, c) removing hexamethylenediamine from the remaining mixture, d) separating 6-aminocapronitrile and adiponitrile from high boilers individually or together, and e) returning 6-aminocapronitrile, adiponitrile or mixtures thereof into step a).
Abstract:
A process for the coproduction of 6-aminocapronitrile (ACN) and hexamethylenediamine (HMD) by treatment of adiponitrile (ADN) with hydrogen in the presence of a nickel-containing catalyst at temperatures not below room temperature and elevated hydrogen partial pressure in the presence or absence of a solvent comprises, after the conversion based on ADN and/or the selectivity based on ACN has or have dropped below a defined value(a) interrupting the treatment of ADN with hydrogen by stopping the feed of ADN and of the solvent, if used,(b) treating the catalyst at from 150 to 400.degree. C. with hydrogen using a hydrogen pressure within the range from 0.1 to 30 MPa and a treatment time within the range from 2 to 48 h, and(c) then continuing the hydrogenation of ADN with the treated catalyst of stage (b).
Abstract:
A catalyst comprising, based on the total weight of the catalyst,more than 6-50% by weight of cobalt, nickel or a mixture thereof,0.001-25% by weight of ruthenium,0-10% by weight of copper and0-5% by weight of promoterson a porous metal oxide carrier can be prepared by(a) impregnating the carrier with the metals, promoters or compounds thereof,(b) drying and calcining the impregnated carrier and(c) reducing the calcined carrier in a stream of hydrogen,carrier not being impregnated with halogen compounds.
Abstract:
A process for preparing 2-cyano-3,3-diarylacrylic esters of the general formula I ##STR1## where R.sup.1 and R.sup.2 are hydrogen, C.sub.1 -C.sub.12 -alkyl groups, C.sub.- C.sub.12 -alkoxy groups or di(C.sub.1 -C.sub.4 -alkyl)amino groups and R.sup.3 is a C.sub.4 -C.sub.18 -alkyl group which can be interrupted by ether-functional oxygen atoms, by reacting a benzophenone imine of the general formula II ##STR2## with a cyanoacetic ester of the general formula III ##STR3## wherein the reaction is carried out at from 20 to 60.degree. C. and, during this, the liberated ammonia is continuously removed from the reaction mixture with the aid of a stream of gas or by reducing the pressure to from 900 to 100 mbar.
Abstract:
A process for removing water and ammonia from benzophenone imine reactor effluents resulting from the catalytic reaction of benzophenones of the formula I ##STR1## where R.sup.1 and R.sup.2, have the meaning stated in the specification and wherein ammonia is distilled off from effluents and wherein water is either distilled off from the effluents over removed non-distillatively.
Abstract:
A process for the coproduction of 6-aminocapronitrile (ACN) and hexamethylenediamine (HMD) by treatment of adiponitrile (ADN) with hydrogen in the presence of a nickel-containing catalyst at temperatures not below room temperature and elevated hydrogen partial pressure in the presence or absence of a solvent comprises, after the conversion based on ADN and/or the selectivity based on ACN has or have dropped below a defined value (a) interrupting the treatment of ADN with hydrogen by stopping the feed of ADN and of the solvent, if used, (b) treating the catalyst at from 150.degree. to 400.degree. C. with hydrogen using a hydrogen pressure within the range from 0.1 to 30 MPa and a treatment time within the range from 2 to 48 h, and (c) then continuing the hydrogenation of ADN with the treated catalyst of stage (b).
Abstract:
Cobalt catalysts whose catalytically active material comprises from 55 to 98 wt % of cobalt, from 0.2 to 15 wt % of phosphorus, from 0.2 to 15 wt % of manganese, and from 0.2 to 15 wt % of alkali metal, calculated as oxide, in which the catalyst material is calcined in a first step at final temperatures of from 550.degree. to 750.degree. C. and in a second step at final temperatures of from 800.degree. to 1000.degree. C., and a process for the hydrogenation of organic nitriles and/or imines, in which the novel cobalt catalyst is used.
Abstract:
A process for preparing aliphatic alpha, omega-diamines by hydrogenation of aliphatic alpha, omega-dinitriles in the presence of a catalyst comprises using a hydrogenation catalyst comprising (a) iron or a compound based on iron or mixtures thereof, (b) from 0.001 to 0.3% by weight based on (a) of a promoter based on 2, 3, 4 or 5 elements selected from the group consisting of aluminum, silicon, zirconium, titanium and vanadium, and also (c) from 0 to 0.3% by weight based on (a) of a compound based on an alkali and/or alkaline earth metal.
Abstract:
A process for recovering hexamethylenediamine (I) from a mixture (II) including(I) hexamethylenediamine,(III) hexamethyleneimine,(IV) a compound selected from 2-aminomethylcyclopentylamine and 1,2-diaminocyclohexane,(V) an imine,(VI) adiponitrile and 6-aminocapronitrileincludes distilling(a) a mixture (II) to obtain(a1) a low boiling fraction (III),(a2) a medium boiling fraction (VII) (I), (IV) and (V), and(a3) a high boiling fraction (V) and (VI),(b) a mixture (VII) to obtain(b1) an overhead product (IV), and(b2) a mixture (VIII) (I) and (V) as bottom product, and(c) a mixture (VIII) to obtain(c1) (I) as overhead product, and(c2) a bottom product (V).