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@PHDTHESIS{Ciptonugroho:690066,
      author       = {Ciptonugroho, Wirawan},
      othercontributors = {Palkovits, Regina and Bitter, Johannes H.},
      title        = {{D}evelopment of modified {Z}r{O}2 catalysts for the
                      production of levulinic acid esters},
      school       = {RWTH Aachen},
      type         = {Dissertation},
      address      = {Aachen},
      reportid     = {RWTH-2017-04817},
      pages        = {1 Online-Ressource (115 ungezählte Seiten) :
                      Illustrationen, Diagramme},
      year         = {2017},
      note         = {Weitere Förderung durch: Indonesian Ministry of National
                      Education Fellowship (DGHE DIKTI fellowship). -
                      Veröffentlicht auf dem Publikationsserver der RWTH Aachen
                      University; Dissertation, RWTH Aachen University, 2017},
      abstract     = {WOx/ZrO2 catalysts have been synthesized with different
                      tungsten loadings and calcination temperatures via one-pot
                      evaporation induced self-assembly (EISA) technique. The
                      tungsten contents and calcination temperatures greatly
                      influence the textural properties of the material. The
                      crystallinity and surface state of materials are confirmed
                      by X-ray diffraction and Laser Raman spectroscopy. The
                      surface acidity of the materials are evaluated by
                      NH3-temperature programmed desorption (NH3-TPD) and diffuse
                      reflectance Fourier transform (DRIFT) with adsorbed
                      pyridine. The catalysts containing 20-25 $wt\%.$ WO3
                      demonstrate the highest surface acidity and population of
                      Brönsted acid centers. The activity of catalyst was tested
                      for Levulinic acid (LA) esterification with 1-butanol
                      (1-BuOH) with mole ratio 2 to 1. The only products after the
                      reaction are pseudo- (p-BL) and normal-butyl levulinate
                      (n-BL). The highest total yield of esters $(67\%)$ and
                      selectivity towards n-BL $(97\%)$ can be attained over 20
                      $wt.\%$ WOx/ZrO2 catalyst calcined at 800 °C. A strong
                      correlation between the population of Brönsted acidity and
                      catalytic activity could be affirmed.The second part of this
                      work elaborates the production of levulinic esters via
                      addition reaction of alpha-angelica lactone (a-AL) with
                      1-BuOH over Amberlyst-36. Full conversion with $97\%$
                      selectivity towards the ester can be achieved by performing
                      the reaction with stoichiometric amount of the reactants at
                      a milder condition. The reaction mechanism for the ester
                      formation has been confirmed revealing that p-BL is the
                      intermediate during the transformation of a-AL to n-BL.
                      Different alcohols have also been studied suggesting the
                      effect of linearity and the length of alkyl chain influence
                      the reaction. This study eventually indicates that a-AL can
                      be used as a better candidate to substitute LA for the
                      synthesis of levulinic acid esters. Different type solid
                      acid catalysts have been tested suggesting that strong
                      acidity is required to allow the addition reaction.Despite
                      possessing strong acid sites, not all acid catalyst can
                      apparently catalyze the addition reaction. The third part of
                      this work is intended to examine the influence of acid
                      species on the addition of a-AL. To realize the
                      investigation, WOx/ZrO2 with adjustable Brönsted population
                      was prepared via EISA and impregnation route. Both methods
                      result in the catalyst with similar textural properties.
                      Raman spectroscopy and X-ray diffraction demonstrated that
                      catalysts prepared by EISA are able to retain meta-stable
                      tetragonal phase of ZrO2 as well as delay the development of
                      WO3 nanoparticles. NH3-TPD and DRIFT with adsorbed pyridine
                      were employed to evaluate the surface acidity. The spectra
                      from pyridine adsorbed at 150°C reveal that the highest
                      Brönsted acid concentration occurs at 15 and 20 $wt.\%$ WO3
                      for the catalysts prepared by impregnation and EISA
                      respectively. The catalysts were employed in the addition
                      reaction of a-AL with 1-BuOH. The conversion of a-AL and
                      selectivity towards n-BL depend strongly on the
                      concentration of Brönsted acid sites. Finally the materials
                      prepared by impregnation method shows higher catalytic
                      activity.},
      cin          = {155310 / 150000},
      ddc          = {540},
      cid          = {$I:(DE-82)155310_20140620$ / $I:(DE-82)150000_20140620$},
      pnm          = {SusChemSys - Sustainable Chemical Synthesis – A Systems
                      Approach (SusChemSys-20151109)},
      pid          = {G:(DE-82)SusChemSys-20151109},
      typ          = {PUB:(DE-HGF)11},
      doi          = {10.18154/RWTH-2017-04817},
      url          = {https://publications.rwth-aachen.de/record/690066},
}