Catalysis of Organic..

Kuusisto, Mikkola and Salmi 237100A100B8080conversion, %60401. batch over sponge nickel1. batch over Ru/C203. batch over sponge nickel5. batch over sponge nickel7. batch over Ru/C00 20 40 60 80 100 120 140 160conversion, %60401. batch over sponge nickel1. batch over Ru/C203. batch over sponge nickel3. batch over Ru/C5. batch over Ru/C00 20 40 60 80 100 120 140 160 180 200 220 240hydrogenation time, minhydrogenation time, minFigure 1. A. Consecutive xylose hydrogenation batches over 2.5 wt-% sponge nickeland 1.5 wt-% Ru/C catalyst. B. Catalyst deactivation during consecutive lactosehydrogenation batches over 5 wt-% sponge nickel and 2 wt-% Ru/C catalyst.Influence of aldonic acids (lactobionic acid and xylonic acid) to reaction rateand catalyst deactivation were tested in consecutive hydrogenations of lactose andxylose over the nickel catalyst, with and without aldonic acid addition in the aqueousreactant solutions (Fig. 2A and 2B). Lactobionic acid seemed to retard more lactosehydrogenation than xylonic acid influenced xylose hydrogenation. Moreover, theabilities of different sugar aldehydes to get dehydrogenated varies (11). In general,sugars containing glucose moiety (such as glucose, lactose and maltose) aredehydrogenated easier than xylose.100A100B8080conversion, %60401. batch without XA addition201. batch, with XA (0.5 wt-%) addition3. batch without XA addition3. batch with XA (0.5 wt-%) addition00 20 40 60 80 100 120hydrogenation time, minconversion, %60401. batch without LBA addition201. batch with LBA (0.5 wt-%) addition3. batch without LBA addition3. batch with LBA (0.5 wt-%) addition00 50 100 150 200 250 300hydrogenation time, minFigure 2. A. Consecutive xylose hydrogenation batches over sponge nickel catalyst(XA=xylonic acid). B. Influence of lactobionic acid (LBA) on lactose hydrogenationrate.