ABSTRACT
The aim of this work was to study the one-pot synthesis of sorbitol via hydrolysis-hydrogenation of cellulose in the presence of Ru-containing composites based on H3PW12O40 supported on ZrO2 and Nb2O5 (Ru-PW/ZrO2 and Ru-PW/Nb2O5). The main parameters impacted the reaction rate and yield of sorbitol, i.e. reaction conditions and type of catalyst were investigated. Ru-PW/ZrO2 systems were more active than Ru-PW/Nb2O5. The yield of sorbitol was found to depend on the activation temperature of PW/ZrO2 and PW/Nb2O5 which affected textural properties, the amount of acid sites and size of Ru nanoparticles. The highest 66% sorbitol yield was observed in the presence of 3%Ru-PW/ZrO2 activated at 550 °C and 1/1 of weight ratio of cellulose/catalyst, 180 °C, 7 MPa hydrogen pressure. This catalyst was stable for three cycles of the reaction without lost of it's activity.
Subject(s)
Ruthenium , Sorbitol , Catalysis , Cellulose , Hydrogenation , HydrolysisABSTRACT
Solid bifunctional catalysts based on cesium salts of V-containing heteropoly acids (CsHPA: Cs3.5H0.5PW11VO40, Cs4.5H0.5SiW11VO40, Cs3.5H0.5PMo11VO40) and Cs2.5H0.5PMo12O40 were used for studying one-pot hydrolysis-oxidation of potato starch to formic acid at 413-443 K and 2 MPa air mixture. It was shown that the optimum process temperature that prevents formic acid from destruction is 423 K. The studies were focused on the influence of the composition of heteropoly anions on the yield and selectivity of formic acid. Using W-V-P(Si) CsHPA results in the product overoxidation compared to Mo-V-containing CsHPA. The activity of Cs-PMo was significantly lower compared to Cs-PMoV. This may indicate that vanadium plays an important role in the oxidation process. The most promising catalyst was Cs3.5H0.5PMo11VO40 which provided the maximum yield of formic acid equal to 51%. Cs3.5H0.5PMo11VO40 was tested during nine cycles of starch hydrolysis-oxidation to demonstrate its high stability and efficiency.
ABSTRACT
In this study, a combination of catalytic and biotechnological processes was proposed for the first time for application in a cellulose biorefinery for the production of 5-hydroxymethylfurfural (5-HMF) and bioethanol. Hydrolytic dehydration of the mechanically activated microcrystalline cellulose over a carbon-based mesoporous Sibunt-4 catalyst resulted in moderate yields of glucose and 5-HMF (21.1-25.1 and 6.6-9.4 %). 5-HMF was extracted from the resulting mixture with isobutanol and subjected to ethanol fermentation. A number of yeast strains were isolated that also revealed high thermotolerance (up to 50 °C) and resistance to inhibitors found in the hydrolysates. The strains Kluyveromyces marxianus C1 and Ogataea polymorpha CBS4732 were capable of producing ethanol from processed catalytic hydrolysates of cellulose at 42 °C, with yields of 72.0±5.7 and 75.2±4.3 % from the maximum theoretical yield of ethanol, respectively.
