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presentation from the World Congress in Chemical Engineering 08, held in Montreal, Canada 26.08 2009

presentation from the World Congress in Chemical Engineering 08, held in Montreal, Canada 26.08 2009

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Wcce08 Pasi Tolvanen Final Presentation Transcript

  • 1. 08/22/09 ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE 8th World Congress of Chemical Engineering, Montreal, August 23 to 27, 2009 P. Tolvanen , P. Mäki-Arvela, A. B. Sorokin, T. Salmi, D. Yu. Murzin, Åbo Akademi Process Chemistry Centre Turku, Finland Collaboration with Institut de Recherches sur la Catalyse-CNRS, Villeurbanne Cedex, France
  • 2.
    • Introduction
    • Starch modification
    • Experimental
    • Results
    ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 3. What is starch and its applications?
    • A polysaccharide carbohydrate in potato, corn, ...
    • Glucose units linked together forms
    • amylose (planar) and amylopectin (branched)
    • Starch modification in industry:
    • - Fuel ethanol by fermentation
    • - Bioplastics, films, hygiene products
    • - pharmaceuticals (vitamins B)
    • - organic chemicals (ascorbic acid, aspartame...)
    • - in paper and board industry
    • as a surface sizing agent
    • as a coating binder
    • --> produced by partial oxidation
    (C 6 H 10 O 5 ) n ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 4.
    • Starch oxidation reactions
    • - introducing carboxyl and carbonyl groups to starch
    • - A degree of substitution (DS) of only 1-20 AGU
    • (anhydro glucose unit) per 100 is of
    • commercial interest.
    Carboxyle Carbonyle Traditional oxidation methods use: - heavy metals (Fe, Cu, W) as catalysts - NaOCl, N 2 O 4 as oxidants ---> large amounts of inorganic waste In our work: Green Chemistry - iron tetrasulfonatophthalocyanine (FePcS) as catalyst - hydrogen peroxide as oxidant ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 5. Reactor setup -1000 ml glass reactor - pH-stat to control pH (2M NaOH) - H 2 O 2 feed 22 ml/h or initially 0.7 w-% in batch mode Parameters - pH = 7-10 - T = 52 degrees celsius - conc. of FePcS catalyst 0.014 mmol/L Typically 260g potato starch added to 800ml deionized water ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 6.
    • Operation policies
    • 1. Starch and catalyst in batch, H 2 O 2 added
    • gradually
    • 2. Starch and H 2 O 2 in batch, catalyst a
    • gradually
    • 3. Starch pretreated with ultrasound, starch
    • and H 2 O 2 in batch, catalyst a gradually
    ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 7.
    • Offline analysis methods
    • Titration of carboxyl groups COOH (and carbonyl groups CO) by modified Smith´s method [2]
    • Iodometric titration of remaining H 2 O 2 concentration in samples
    • Separation of organic low-mol. weight compounds by extraction (ethyl acetate)
    • GC-MS for identification of low-mol. weight compounds
    • (e.g. oxalic, lactic, malonic acid )
    • Quantitative analysis of low-mol. weight compounds by GC
    • SEM, nitrogen adsorption for granular surface structure and surface area.
    [2] R.J. Smith, Starch: Chemistry and technology, 2 (1967) 620-625 ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 8. In our previous study [1] : Semibatch by feeding H 2 O 2 constantly to reactor Slightly alkaline environment.: pH 7-10 H 2 O 2 constant feed at 22 ml/h (30%) catalyst (FePcS) added initially reaction time 7h --> high pH gave good degree of substitution but not good yield [1] Tolvanen et al. Chem . Eng. J. (2009) ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 9.
    • New approaches
    • - All H 2 O 2 + catalyst added at start of the reaction
      •  broader understanding of H 2 O 2 decomposition
      •  easier kinetics
      •  study of catalyst deactivation
      • - H 2 O 2 added instantly, catalyst solution fed into to reactor
      • - Starch pretreated with ultrasound
      •  higher surface available for reaction
    ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 10.
    • Results
    • DS COOH and H 2 O 2 concentrations - H 2 O 2 -batch, at pH 7.5, 8.4 and 10
    ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 11.
      • SEM
    Native potato starch BET: 10 m 2 /g Native potato starch treated with ultrasound 24 h at 38 deg. celsius BET: 18m 2 /g Ultrasound treated starch after reaction in pH = 8.4 ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 12.
    • Results
    • DS COOH and H 2 O 2 concentrations - with or without ultrasound pretreated
    • starch, H 2 O 2 -batch, at pH 8.4
    30 % higher yield ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 13.
    • Results
    • DS COOH and H 2 O 2 concentrations – H 2 O 2 -batch, catalyst solution
    • feed 12 mg cat /h for 10h
    50 % higher yield ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 14.
    • Left: catalyst and H 2 O 2 only, compared with using starch in same
    • conditions. Right: Effect of temperature increase on H 2 O 2 decomposition
    ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 15.
    • Summary of COOH and H 2 O 2 results:
    h ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 16.
    • Low molecular products
    • GC extraction: 2 ml of aqeous phase from sample, acidified and
    • extracted with aid of ethyl acetate, and run with GC. Betulinol used as
    • internal standard
    • Low molecular :
    • hydroxyacetic acid (glycolic acid ) - high formation at pH 10
    • Ethanedioic acid (oxalic acid) - high formation at pH 10
    • Lactic acid – lower pH favors formation
    • 2,3-dihydroxypropanoic acid – high formation at pH 10
    • + Formic acid (probably high concentration), can be determined by HPLC
    • + over 30 other unidentified, lower concentration compounds
    ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 17.
    • Conclusions
    • Starch oxidation is studied using a cheap iron complex FePcS as a catalyst, and hydrogen peroxide as an oxidant, resulting in a waste free oxidation method.
    • By optimizing rection contions to constantly feeding catalyst during reaction, higher DS values were obtained compared to batch mode. DS still lower than when constantly feeding H 2 O 2 .
    • Experiments with both catalyst and H 2 O 2 are of future interest
    • Ultrasound pretreated starch reacts faster in beginning, but conversion remains moderate.
    • Experiments using ultrasound during reaction is of future interest.
    ENVIRONMENTALLY FRIENDLY CATALYTIC STARCH OXIDATION BY HYDROGEN PEROXIDE
  • 18.
    • Thank you for your kind attention!
    • Questions...?
    Department of Industrial Chemistry and reaction Engineering Åbo Akademi Univesity Turku/Åbo Suomi/Finland