Hledat publikace

Glycerol is produced in large quantities as byproduct from biodiesel (FAME) production can be utilized not only in the manufacture of specialties but also as a substitute for traditional petrochemical intermediates, mainly for propylene. One of the most promising ways of glycerol utilization is its catalytic hydrogenolysis to 1,2-propanediol. In recent years, the mixed oxides catalysts containing Cu, other bivalent metal and Al oxides, prepared by thermal decomposition of hydrotalcite-like structures, attracted attention as very promising catalysts for glycerol hydrogenolysis. The role of second bivalent metal content in hydrotalcite-like precursor (besides Cu2+) was studied in our study. These experiments were aimed at the preparation and comparative testing of the catalysts prepared from hydrotalcite-like structures, which contained Zn, Fe, Ni or Co as the second bivalent metal (M), besides copper. Cu/M/Al hydrotalcite with molar ratio 2:1:1 was precipited at the condition of controlled pH (9,5), temperature (60 °C) and continuous introduction of the source solutions within s period of 30 min. The precipitate was then filtered, dryed, calcined and activated. The activated catalysts were tested in glycerol hydrogenolysis at 230 °C, and the hydrogen pressure of 7 MPa in a batch autoclave. Catalyst loading was 0,05. The Zn containing catalyst appeared to be the most active one from the whole set of the catalysts prepared. The selectivity to 1,2-propanediol of 93 % at 97 % glycerol conversion was achieved with this catalyst while the selectivity values only around 70 % could be achieved with other catalysts. The Ni modified catalyst was characterized as having the lowest activity and selectivity among the whole group of the catalysts prepared.