2007 Spring Symposium

 
Jaime R. Blan­ton^1*, Taku­ma Hara², Kon­rad Möbus³ and Baoshu Chen^3
1Degus­sa Corporation,5150 Gilbertsville High­way, Calvert City, KY 42029 (USA)
²Degus­sa Japan, Tsuku­ba Mina­mi Dai­ichi Kogyo Danchi, 21 Kasum­i­nosato Ami-machi, Inashi­ki-gun Ibara­ki-ken 300‑0315 (Japan)
³Degus­sa Ag,Rodenbacher Chaussee 4, 63457 Hanau-Wolf­gang (Ger­many)
^*jaime.​blanton@​degussa.​com

Abstract — ε-capro­lac­tam is a feed­stock for nylon-6 poly­mers. The demand for ε-capro­lac­tam was 4 mil­lion met­ric tons in 2005. Hydrox­y­lamine (hyam) is a key raw mate­r­i­al for the man­u­fac­ture of ε-capro­lac­tam. The hydrox­y­lamine used in the HPO™ is pro­duced by selec­tive hydro­gena­tion of nitric acid over a Pd/C cat­a­lyst. Degus­sa has done exten­sive work to devel­op Pd/C cat­a­lysts with supe­ri­or activ­i­ty for the pro­duc­tion of hyam (Equa­tion 1).

Equa­tion 1: NO₃⁻ + 3H₂ + 2H⁺ → NH₃OH⁺ + 2H₂O

Many para­me­ters influ­ence the per­for­mance of a cat­a­lyst. Our aim was to see how vary­ing the car­bon sup­port, Pd load­ing and Pt addi­tion would affect the activ­i­ty, selec­tiv­i­ty and fil­ter­abil­i­ty of the cat­a­lyst in hopes of iden­ti­fy­ing the opti­mal cat­a­lyst for the hyam reac­tion (activ­i­ty greater than 25 g hyam/g Pd, selec­tiv­i­ty >; 90% and fast fil­tra­tion rate).

Numer­ous cat­a­lysts were pre­pared by sev­er­al dif­fer­ent meth­ods and test­ed for their hyam activ­i­ty. Cat­a­lysts (six in total; A-F) pre­pared using the method that pro­vid­ed the most active cat­a­lysts were used in this study. These cat­a­lysts were each pre­pared by the same pro­pri­etary pro­ce­dure and each con­tains 10% Pd except D which con­tains 9% Pd. In a typ­i­cal test 750 mg of cat­a­lyst was added to a con­tin­u­ous stirred tank reac­tor (1500 rpm) con­tain­ing the nitrate ions in 1L of phos­phate buffer solu­tion. The amount of hyam formed and selec­tiv­i­ty after 90 min at 30 °C were mea­sured by titra­tion. Cat­a­lyst fil­tra­tion rates were mea­sured by pass­ing a slur­ry of buffer solu­tion con­tain­ing 5 g cat­a­lyst through a fil­ter cloth at 0.1 MPa N₂ pres­sure.

From this study it is evi­dent that sev­er­al high­ly active hyam cat­a­lysts have been devel­oped for the HPO™ process. Depend­ing on which per­for­mance indi­ca­tor is most impor­tant (activ­i­ty, selec­tiv­i­ty or fil­ter­abil­i­ty) one can select the best Degus­sa cat­a­lyst for their appli­ca­tion.
 
Table 1: Activ­i­ty (g hyam/g Pd) and selec­tiv­i­ty for bimetal­lic cat­a­lysts and cat­a­lysts of vary­ing Pd load­ings.

 
Fig­ure 1: Hyam activ­i­ty vs. fil­tra­tion of cat­a­lysts.