abstracts - Институт катализа им. Г.К. Борескова

OP-II-8CATALYTIC AND PHYSICOCHEMICAL PROPERTIES OF Pt/α-GeO 2 SYSTEMSIN REACTION OF SLECTIVE HYDROGENATION OF α,β-UNSATURATEDALDEHYDES IN A GAS PHASEGebauer-Henke E., Rynkowski J.Institute of General and Ecological Chemistry, Technical University of Łódź,90-924 Łódź, Żwirki 36, PolandE-mail: egebauer@mail.p.lodz.plThe production of unsaturated alcohols from α,β-unsaturated aldehydes is a veryimportant reaction in the preparation of many pharmaceutical, agrochemical, fragrancecompounds and fine chemicals.Hydrogenation reactions are mostly carried out with supported group VIII metalcatalysts. Thermodynamically the hydrogenation of the carbonyl group into an unsaturatedalcohol is not favored. It was found that the addition of promoters [1, 2] and the use ofbimetallic catalysts [3] improve largely the selectivity to unsaturated alcohols of platinumbased catalysts. An improvement of selectivity towards unsaturated alcohols can be achievedby using various promoters like Sn, Ge and Ga [2, 4]. The promoting effect of Ga and Ge canbe explained by the sorption of the C=O group at the Pt – metal oxide interface, where it canbe activated by the Lewis acide site and dissociated hydrogen can be supplied by Pt. At PtGaand PtGe species such activation leads to high rate of unsaturated alcohol formation [5].α-GeO 2 (S BET = 3,8 m 2 /g) was impregnated with a methanolic solution of Pt(acac) in theamount appropriate to obtain 1, 2 and 5 wt. % of platinum. The real content of platinum in thecatalysts was very close to the nominal one, which was checked by ICP analysis. Thecatalysts were dried at 100 o C for 2 hrs and calcined in air at 500 o C for 2 hrs.Support and catalysts were characterized by BET, TEM, XRD,, TPR, FTIR and TG-DTAmethods.Most of the catalytic tests were performed at a reaction temperature of 80 o C. Bothactivity and selectivity to the crotyl alcohol were much higher than in the experiments carriedout in 50 o C. For all catalysts under study the maximum is reached for the samples reduced at120 o C. The reduction of the catalyst at the temperatures from 170 o C results in a remarkabledrop of activity, whereas the catalysts reduced at the temperatures above 200 o C are inactive.The changes of the catalysts activity and selectivity during the time on stream are given inFig. 1a and b. All catalysts show a deactivation period, about 120 min. After 120 min. theactivity remains stable, the reaction is occurring in the quasi steady – state regime. The197