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@PHDTHESIS{Simitsis:1015640,
      author       = {Simitsis, Natalia Milena},
      othercontributors = {Palkovits, Regina and Liauw, Marcellus},
      title        = {{E}ntwicklung eines {K}atalysator- und {R}eaktorsystems
                      für die wasserstoffeffiziente {H}erstellung des
                      synthetischen {K}raftstoff(additivs) {D}imethoxymethan},
      school       = {RWTH Aachen University},
      type         = {Dissertation},
      address      = {Aachen},
      publisher    = {RWTH Aachen University},
      reportid     = {RWTH-2025-06495},
      pages        = {1 Online-Ressource : Illustrationen},
      year         = {2025},
      note         = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
                      University; Dissertation, RWTH Aachen University, 2025},
      abstract     = {The non-oxidative dehydrogenation (NOD) of methanol in the
                      gas-phase is a H$_{2}$-efficient route for the synthesis of
                      the sustainable fuel additive dimethoxymethane (DMM).
                      Overcoming the thermodynamic limitation and suppression of
                      by-products are the central challenges. Therefore, in this
                      work, a new catalyst and reactor system was developed to
                      improve catalytic activity, DMM selectivity, stability, and
                      induction period, as well as to expand the knowledge about
                      structure-activity relationships. To achieve this, new
                      bifunctional catalysts with dehydrogenative and Lewis-acidic
                      functionality were systematically developed based on the
                      previously established benchmark Cu/Hβ catalyst. Initially,
                      the Cu/Hβ catalyst was investigated for its reproducibility
                      and storage properties, establishing a new reproducible
                      benchmark for catalytic performance (DMM selectivity: 58.1
                      ± 0.4\%; catalytic activity: 5.05 ± 0.23
                      mmol$_{MeOH}$/h/g$_{cat}$). Furthermore, the Cu/Hβ catalyst
                      can be tailored regarding its dehydrogenative and acidic
                      properties (Cu loading or SiO$_{2}$/Al$_{2}$O$_{3}$ ratio)
                      so that one of the valuable products (i.e., DMM, dimethyl
                      ether (DME), or methyl formate (MF)) is formed as the main
                      product with over 75\% selectivity, respectively.
                      Furthermore, the dynamic Cu oxidation state serves as a
                      descriptor for the catalytic performance. Zr doping of the
                      Cu/Hβ catalyst leads to a decrease in DMM productivity but
                      increases stability and shortens the induction phase. Next,
                      new metals were evaluated as dehydrogenative sites on the
                      Hβ zeolite, where Ag was identified as the most promising
                      candidate. The optimized Ag/Hβ catalyst achieves a high DMM
                      selectivity of 73.6\% at 240 °C with an activity of 2.04
                      mmol$_{MeOH}$/h/g$_{cat}$. It is particularly characterized
                      by higher robustness and stability compared to the benchmark
                      Cu/Hβ catalyst. Dynamic in situ changes of the Ag oxidation
                      state are also observed when using the Ag/Hβ catalyst,
                      which can serve as a descriptor for the long induction
                      phase. In subsequent investigations for new Cu loaded
                      support materials, amorphous SiAl mixed oxides (ASAs) show
                      the highest DMM selectivity compared to mixed oxides with
                      other element combinations. The influence of the Si/Al
                      ratio, Cu loading, and calcination temperature was
                      systematically investigated. The optimized Cu/SiAl catalyst
                      achieves a DMM selectivity of 55.9\% at 200 °C with a
                      catalytic activity of 1.02 mmol$_{MeOH}$/h/g$_{cat}$ after
                      6000 min. Consequently, crystalline microporous zeolite
                      frameworks are not necessarily required for selective DMM
                      formation. Finally, to overcome the thermodynamic limitation
                      of the NOD of methanol to DMM, a membrane reactor was
                      designed and constructed to in situ separate H$_{2}$
                      released during the reaction and therefore potentially shift
                      the thermodynamic equilibrium towards the product side.},
      cin          = {155310 / 150000},
      ddc          = {540},
      cid          = {$I:(DE-82)155310_20140620$ / $I:(DE-82)150000_20140620$},
      pnm          = {DFG project G:(GEPRIS)512546329 - Entwicklung
                      fortschrittlicher Katalysatoren für die
                      Dimethoxymethan-Synthese durch nichtoxidative Dehydrierung
                      von Methanol in der Gasphase (512546329) / BMBF 03SF0566P0 -
                      Verbundvorhaben NAMOSYN (BMBF-03SF0566P0)},
      pid          = {G:(GEPRIS)512546329 / G:(DE-82)BMBF-03SF0566P0},
      typ          = {PUB:(DE-HGF)11},
      doi          = {10.18154/RWTH-2025-06495},
      url          = {https://publications.rwth-aachen.de/record/1015640},
}