L-sorbose oxidation

The oxidation reactions were performed in a glass batch reactor, equipped with magnetic stirrer (mechanic for L-sorbose oxidation), reflux condenser and thermometer. The reaction conditions are summarized in Table I. Before reaction the catalyst was pre-reduced in situ in a nitrogen atmosphere ( 20 min) with the alcohol reactant in 30-40 ml alkaline water (and dodecylbenzenesulfonic acid sodium salt detergent for water-insoluble reactants). The reactor worked in a mass transfer limited regime, controlled by the air flow rate (7.5-20 cm3min 1) and the mixing rate (1500-1800 min 1). The reactions were followed by GO or HPLC analysis. 

Sorbitol to L-sorbose oxidation (in vitamin C production) Gluconobacter suboxydans... 

Figure 1. Formation of nanoparticles in polymer nanocavities 2.2. L-sorbose oxidation...

The catalysts tested in L-sorbose oxidation showed to be very active(Table 1). Table 1. L-sorbose oxidation (catalyst concentration 4.5-10 g/L, initial sorbose... 

Table 3.5 Catalytic properties of L-sorbose oxidation with Pt-containing nanostructured catalysts 1 . ...

As can be seen from Table 3.5 ( 4), Pt nanoparticles formed in HPS are more selective in L-sorbose oxidation than the catalysts based on block copolymers but still the selectivity is not sufficient We believe that low selectivity may be attributed to saturation of the nanoparticle surface with H2 during reduction, which alters the sorption-desorption equilibria of the L-sorbose, oxygen and 2-keto-L-gulonic acid [89]. As was demonstrated in Ref [96], L-sorbose oxidation can be catalyzed not only with Pt(o) but also in the presence of Pt ions. This prompted us to investigate the catalytic properties of HPS-Pt without Pt ion reduction. 

We studied the effect of temperature on the kinetics of L-sorbose oxidation over the range 60-80 °C. Increasing temperature yields an increase in the rate of L-sorbose oxidation both for HPS-Pt-2 and MN-270-Pt . The temperature depen-... 

Unlike hydrogenation of acetylene alcohols, for L-sorbose oxidation the kinetic studies have not yet been extended to computation of the kinetic models because of the high complexity of the mechanism of L-sorbose oxidation. 

Broennimann, C., Bodnar, Z., Aeschimann, R., et al. (1996). Platinum Catalysts Modified by Adsorbed Amines A New Method of Enhancing Rate and Selectivity of L-sorbose Oxidation, J. Catal, 161, pp. 720-729. 

Suhnan, E., Matveeva, V, Bronstein, L., etal (2003). Platinum-containing Polymeric Catalysts in Direct L-sorbose Oxidation, Green Chem. 5, pp. 205-208. 

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