Abstract:
The present invention relates to a process for purifying adiponitrile (ADN), wherein crude ADN is introduced into a rectification apparatus (R1). The rectification apparatus (R1) comprises a first side draw and preferably also a second side draw, the first side draw being disposed below the crude ADN introduction point and the optional second side draw being disposed above the crude ADN introduction point. The first side draw is used to draw off a gaseous stream comprising ADN while the optional second side draw is used to draw off undesired by-products such as 1-amino-2-cyanocyclopentene (ACCP) which are often generated in ADN production and consequently may be present in the crude ADN. The gaseous stream from the first side draw of (R1) is introduced into a second rectification apparatus (R2). (R2) is used to separate off ADN from remaining high boilers and any other by-products present, pure ADN being drawn off from (D2) as overhead product. It is preferable when the process according to the invention employs crude ADN from a reaction of butadiene with hydrocyanic acid (HCN).
Abstract:
A process is described for preparing 3-pentenenitrile, characterized by the following process steps: (a) isomerizing a reactant stream which comprises 2-methyl-3-butenenitrile over at least one dissolved or dispersed isomerization catalyst to give a stream 1 which comprises the at least one isomerization catalyst, 2-methyl-3-butenenitrile, 3-pentenenitrile and (Z)-2-methyl-2-butenenitrile, (b) distilling stream 1 to obtain a stream 2 as the top product which comprises 2-methyl-3-butenenitrile, 3-pentenenitrile and (Z)-2-methyl-2-butenenitrile, and a stream 3 as the bottom product which comprises the at least one isomerization catalyst, (c) distilling stream 2 to obtain a stream 4 as the top product which, compared to stream 2, is enriched in (Z)-2-methyl-2-butenenitrile, based on the sum of all pentenenitriles in stream 2, and a stream 5 as the bottom product which, compared to stream 2, is enriched in 3-pentenenitrile and 2-methyl-3-butenenitrile, based on the sum of all pentenenitriles in stream 2, (d) distilling stream 5 to obtain a stream 6 as the bottom product which comprises 3-pentenenitrile and a stream 7 as the top product which comprises 2-methyl-3-butenenitrile.
Abstract:
The invention relates to a method of production of catalyst particles, comprising platinum and tin and also at least one further element, selected from lanthanum and cesium, on zirconium dioxide as support, comprising the steps: preparation of one or more solutions containing precursor compounds of Pt, Sn and at least one further element of La or Cs and also ZrO2, converting the solution(s) to an aerosol, bringing the aerosol into a directly or indirectly heated pyrolysis zone, carrying out pyrolysis, and separation of the particles formed from the pyrolysis gas.Suitable precursor compounds comprise zirconium(IV) acetylacetonate, lanthanum(II) acetylacetonate and cesium acetate, hexamethyldisiloxane, tin 2-ethylhexanoate, platinum acetylacetonate, zirconium(IV) propylate in n-propanol and lanthanum(II) acetylacetonate.The invention also relates to the catalyst particles obtainable using the method according to the invention, and to the use thereof as dehydrogenation catalysts.