Реферат: Efficient, inexpensive and stable to coking nanocomposite catalysts for transformation of natural gas/biogas/biofuels into syngas and hydrogen were developed comprised of nanoparticles of metals/alloys (Ni, Co, Pt, Ni+Pt, Ni+Ru) supported on perovskites (La1-xPrxMn1-yCryO3-, CaTiO3), fluorite Ln-Ce-Zr-O (Ln = La, Pr, Sm), rutile (Ln)TiO2 and spinel MnxCr3-xO4 oxides with a high oxygen mobility and reactivity, either bulk or supported on Mg-doped alumina or MgAl2O4 with ordered mesoporous structure. Pulse microcalorimetry and transient kinetic studies (including SSITKA and FTIRS in situ for estimation of rate constants of reaction steps) revealed that mechanism of biofuels transformation on these catalysts can be described by a bifunctional red-ox scheme with activation of fuel molecules on Me/oxide sites and oxidants (H2O, CO2, O2)- on reduced sites of the oxide support. Fast diffusion of surface oxygen (bridging M2O) species to the Me/support interface provides the efficient transformation of activated fuel species into syngas by incorporation into C-C bond, thus preventing coking. Effect of the active component composition, specificity of the surface sites and nature of oxidant on mechanism of biofuels transformation into syngas was elucidated. Structured catalysts comprised of optimized active components loaded on Ni-Al foams, Fechraloy foils/honeycombs, gauzes and microchannel platelets protected by corundum layers were tested in pilot reactors in steam, dry, partial oxidation and autothermal reforming of biofuels at short contact times using concentrated feeds. A high yield of syngas approaching equilibrium and stable performance without coking were demonstrated even for such fuels as glycerol, sunflower and turpentine oils. Mathematical modeling demonstrated absence of any heat transfer limitations due to a high thermal conductivity of substrates. No spallation or cracking of the active component layers supported on substrates was revealed. Reactors equipped with the internal heat exchanger were designed allowing stable and efficient operation in the autothermal mode of the mixture of natural gas and liquid biofuels at feeds inlet temperatures <50oC.[1]. For the renewable/hydrogen energy field, producing syngas and hydrogen from biogas/biofuels using catalytic processes conjugated with reagent (oxygen) and/or products (hydrogen) separation in membrane reactors is a promising approach as well. Unique Ni-Al foam substrates with graded porosity were used for design of such membranes [2], which allowed to minimize gas diffusion resistance. Nanocomposites with mixed ionic-electronic conductivity were applied as permselective layers for oxygen separation (perovskite+fluorite, spinel+fluorite combinations) or hydrogen separation (Ni-Cu nanoalloys + Ln tungstates, niobates etc. protonic conductors). Nanocomposite active components for biofels transformation were supported on membrane surface as well as on the honeycomb substrates placed into membrane reactors. For catalytic oxygen-permeable membrane reactors a high oxygen flux (up to 15 cm3 O2/cm2min) was achieved under air/CH4 (+CO2 + biofuel) feeds gradients at ~ 900 oC, providing a high yield of syngas. For reactors with hydrogen-permeable membranes a better performance was achieved with honeycomb catalyst put upstream, so at ~ 800 oC complete EtOH conversion in steam reforming and a high hydrogen permeation (up to 3 cm3 H2 /cm2 min) were demonstrated. Membranes remained stable without any deterioration of performance or coke deposition. Mathematic modeling using modern software (COMSOL Multiphysics, CFD), step-wise reaction scheme of fuels reforming and mass transport equations provided reliable description of catalytic membrane performance required for up-scaling. References [1] Sadykov, V.; Simonov, M.; Eremeev, N.; Mezentseva, N. Modern Trends in Design of Catalysts for Transformation of Biofuels into Syngas and Hydrogen: From Fundamental Bases to Performance in Real Feeds. Energies 2021, 14, 6334. https://doi.org/10.3390/en14196334 [2] V. A. Sadykov, L. N. Bobrova, N. F. Eremeev et al, Advanced Materials for Solid Oxide Fuel Cells and Membrane Catalytic Reactors, Chapter 12 in Book “Advanced Nanomaterials for Catalysis and Energy” (V.A. Sadykov, Ed.). 2019 Elsevier Inc., pp. 435-514, https://doi.org/10.1016/B978-0-12-814807-5.00012-7 Acknowledgements. Support by Russian Scientific Foundation (16-13-00112 Project) and Russian Ministry of Education and Science (АААА-А21-121011390007-7 and АААА-А21-121011390009-1 projects ) is gratefully acknowledged

Библиографическая ссылка: Sadykov V.A. , Eremeev N.F. , Bobrova L.N.
Transformation of Biofuels into Syngas and Hydrogen In Reactors with Structured Catalysts and Hydrogen Permselective Membranes
1st Sustainable Bioenergy and Processes Conference 13-15 Dec 2021