Catal. Our calculations reveal that both OI and OII could be hydrogen accepters during the dehydrogenation steps due to the close energy barriers. Phys. As shown in Fig. The subsequent re-oxidation of vanadium cation to V5+ with molecular oxygen replenished V=O and completed the catalytic cycle. Henkelman, G., Uberuaga, B. P. & Jnsson, H. A climbing image nudged elastic band method for finding saddle points and minimum energy paths. The first-generation PFBC system also uses a sorbent and jets of air to suspend the mixture of sorbent and burning coal during combustion. Based on the foregoing multipulse NH3 experiments, it can be concluded that the ammonia oxidation to nitric oxide over V2O5 in the proposed CLAO process proceeds via a modified, temporally separated MvK scheme. a HRTEM image of the as-calcined V2O5 sample and the corresponding Fast Fourier transforms (FFTs) image (inset). The highest frequency mode at 994cm1 has been attributed to the shortest vanadyl (V=O) stretch within VO5 square pyramids. ] This page was last edited on 27 October 2022, at 10:55. [21][22] Additional material and heat balances can be made to quantify the thermal advantage from preheating the combustion air,[23][24] or enriching it in oxygen.[25][26]. Mothers Name 4. The spectra signals were calibrated before each experiment with calibration gas of known compositions (5.0% NH3/Ar, 6006 ppm NO/Ar, 3002 ppm N2O/Ar, 5007 ppm N2/Ar, 4995 ppm H2/Ar). In particular, the catalytic roles of different oxygen sites are investigated in detail. Kinetic modeling of dynamic changing active sites in a Mars-van Krevelen type reaction: ethylene oxychlorination on K-doped CuCl2/Al2O3. Naik, M. Gigantino, A. Steinfeld 77, 3865 (1996). In complete combustion, the reactant burns in oxygen and produces a limited number of products. Physical and chemical properties. + Ed. Neal, L. M., Haribal, V. P. & Li, F. Intensified ethylene production via chemical looping through an exergetically efficient redox scheme. Oxy-fuel combustion; Chemical looping; Other carbon capture processes. Catal. 2 R Moncada, J., Adams, W. R., Thakur, R., Julin, M. & Carrero, C. A. m Raman spectra were collected during the reduction process until a constant intensity (or complete disappearance of the peak) was achieved. 136, 77517761 (2014). Combustion is often a complicated sequence of elementary radical reactions. For comparison, the atomic N* was also considered as the intermediates. Chemical looping combustion (46) Chemical looping reforming (16) Chemical looping gasification (4) Molecular engineering. = 4b), indicating the reversible structural changes upon re-oxidation. Appl. This temporally separated MvK scheme avoids direct competition of reduction and reoxidation on the same V=O active sites that would otherwise be inevitable in a co-feed scheme, leading to remarkable enhancement in catalyst performance. The temperature and quantity of offgas indicates its heat content (enthalpy), so keeping its quantity low minimizes heat loss. The GGA + U method was chosen to describe partially filled 3d orbitals in V with U=4eV and J=0.68eV for Hunds exchange interaction70. The V=O species were regenerated following oxidation, restoring the high NO selectivity. 52, 52355244 (2013). High-resolution transmission electron microscopy (HRTEM) characterization was implemented on a JEOL JEM-2200F microscope operated at 200kV with a linear resolution of 0.10nm. Catal. Chemical warfare (2) Privacy Policy * This discount is valid for all authors who wish to publish Open Access and submit their article by June 30, 2023. Chemical looping combustion (7) Chemical looping reforming (4) Microreactors (7) Military science (5) Molecular engineering. Raman spectra were taken during the oxidation process until a constant intensity was achieved. Additionally, these shapes have a low pressure drop which is advantageous for this application. S The reduction degree of V2O5 determined by XRD, XPS, and XANES was compared in TableS3. In CLC, a metal oxide is employed as a bed material providing the oxygen for combustion in the fuel reactor. Petrochemicals (1) Reaction engineering (1) Nanoscience. Pinaeva, L. G. et al. NH3 is first activated by the lattice oxygen of V2O5 redox catalyst in the absence of gas-phase oxygen, yielding NOx and a reduced VOx center. Combustion of hydrocarbons is thought to be initiated by hydrogen atom abstraction (not proton abstraction) from the fuel to oxygen, to give a hydroperoxide radical (HOO). volume13, Articlenumber:718 (2022) Provided by the Springer Nature SharedIt content-sharing initiative. Employing oxygen without nitrogen and the trace gases found in air eliminates the primary source for the formation of nitrogen oxide (.mw-parser-output .template-chem2-su{display:inline-block;font-size:80%;line-height:1;vertical-align:-0.35em}.mw-parser-output .template-chem2-su>span{display:block}.mw-parser-output sub.template-chem2-sub{font-size:80%;vertical-align:-0.35em}.mw-parser-output sup.template-chem2-sup{font-size:80%;vertical-align:0.65em}NOx), produces a flue gas composed primarily of carbon dioxide and water vapor; other trace pollutants depend on the fuel selected. Oxidants for combustion have high oxidation potential and include atmospheric or pure oxygen, chlorine, fluorine, chlorine trifluoride, nitrous oxide and nitric acid. Advances in CO2 capture processes (post combustion, pre combustion, oxy combustion) for power plants, cement and steel plants, refineries, petrochemicals, and other large industries; Chemical Looping, that uses solid oxygen carriers to transfer oxygen, would result an approach to reduce GHG emissions and facilitate the capture of CO2. Oxygen Carrier Assisted Chemical Looping Combustion (Project No. When the ATR uses carbon dioxide, the H2:CO ratio produced is 1:1; when the ATR uses steam, the H2:CO ratio produced is 2.5:1. z 407, 128013 (2021). Nat. Optimal SMR reactor operating conditions lie within a temperature range of 800C to 900C at medium pressures of 20-30 bar. A 289, 97103 (2005). Chemical looping. To obtain a deeper insight into the mechanistic details, XANES was used to determine the evolution of the vanadium oxidation state and coordination environment during the reaction. Sommaire dplacer vers la barre latrale masquer Dbut 1 Histoire Afficher / masquer la sous-section Histoire 1.1 Annes 1970 et 1980 1.2 Annes 1990 1.3 Dbut des annes 2000 2 Dsignations 3 Types de livres numriques Afficher / masquer la sous-section Types de livres numriques 3.1 Homothtique 3.2 Enrichi 3.3 Originairement numrique 4 Qualits d'un livre Accounts of Chemical Research has been certified as a transformative journal by cOAlition S, committing to a transition to 100% open access in the future. For example, excess combustion air of 15 percent means that 15 percent more than the required stoichiometric air is being used. H k Baddour-Hadjean, R. & Pereira-Ramos, J. P. Raman microspectrometry applied to the study of electrode materials for lithium batteries. Zhu, M., Lai, J. K., Tumuluri, U., Wu, Z. For each dehydrogenation step, all possible hydrogen accepter sites were examined. 7, 41044117 (2014). Isupova, L. A. et al. = [3] Later it was proposed as a system for increasing power station efficiency. ACS Catalysis 8, 89768986 (2018). This gives CLC clear benefits when compared with competing carbon capture technologies, as the latter generally involve a significant energy penalty associated with either post combustion scrubbing systems or the work input required for air separation plants. Chem. Chemical looping. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate. However, non-radical intermediates are stable and are produced in incomplete combustion. Petrochemicals (1) Biology and biological chemistry. Article Self cleaning surfaces (1) Surface modification (1) Analytical chemistry. However, they have some disadvantages such as erosion on the tubes inside the boiler, uneven temperature distribution caused by clogs on the air inlet of the bed, long starting times reaching up to 48 hours in some cases. Nat. An intermediate in the combustion of carbon and hydrocarbons, carbon monoxide, is of special importance because it is a poisonous gas, but also economically useful for the production of syngas. S 6c. Typical S/C ratio values lie within the range 2.5:1 - 3:1.[7]. Assuming perfect combustion conditions, such as complete combustion under adiabatic conditions (i.e., no heat loss or gain), the adiabatic combustion temperature can be determined. L.L. Synthesis of hierarchical sisal-like V2O5 with exposed stable {001} facets as long life cathode materials for advanced lithium-ion batteries. Prior to use, the calcined sample was ground into a fine powder using a mortar and pestle. Chemical looping combustion (4) Military science (3) Desulfurization (2) Risk assessment (1) Polymer science. x The decreased NO formation with a concurrent increase in N2 formation at higher temperatures (600650C) can be related to the selective catalytic reduction (SCR) of NO with NH3. Zhu, X., Imtiaz, Q., Donat, F., Mller, C. R. & Li, F. Chemical looping beyond combustion a perspective. ACS Catalysis 11, 21412149 (2021). After CLAO cycling, V6O13 and VO2 peaks vanished, implying that the reduced phase was completely reoxidized. Fluidized bed combustion (FBC) is a combustion technology used to burn solid fuels.. & Dennis, J. S. Chemical looping epoxidation. View historical data and other metrics on Journal Insights. Nat. It is a typically incomplete combustion reaction. b V 2p XPS spectra of V2O5 sample: (i) as calcined, (ii) after 30 pulses of NH3 reduction, (iii) after 120 pulses of NH3 reduction, and (iv) after CLAO redox cycling at 650C. Rev. Male/Female Biology. This arrangement requires the redox reactions to be exothermic and endothermic respectively, but this is normally the case for most metals. Combustion is also currently the only reaction used to power rockets. In this section, thorough physicochemical characterization combined with density functional theory calculations were employed to reveal the catalyst structureactivity relationship. an innovative process for poly-generation of power, heat, and chemicals from waste (waste-to-energy, WtE) providing a concentrated stream of CO2 that is ready for transport and storage or utilization. Odorants (5) Metabolic engineering (4) Military science (2) Molecular engineering. Article m Such devices are required by environmental legislation for cars in most countries. Google Scholar. H 206 In typical co-feed mode, steady-state ammonia oxidation was carried out using feeds containing 5% NH3/Ar (30mLmin1) and O2 (12.86mLmin1) with the effective O2 percentage of 30%. Nuclear fission (1) Nuclear medicine (1) Chemical biology. H HVAC contractors, firefighters and engineers use combustion analyzers to test the efficiency of a burner during the combustion process. 202, 5163 (2017). As shown in Fig. 128, 1111411123 (2006). J. Meanwhile, XPS results give a higher V4+ portion (a higher reduction extent) at different NH3 pulse numbers, which is due to the surface sensitivity of the XPS measurement. Blchl, P. E. Projector augmented-wave method. Combined with the XRD results, the increase in local symmetry originates from the progressive evolution from strongly distorted square-pyramidal VO5 groups in V2O5 to less distorted octahedral VO6 groups in V6O13 and VO2 (Fig. The reaction takes place in a single chamber where the methane is partially oxidized. Energy 5, 910919 (2020). Leung, Philip C.W. In particular, the catalytic roles of different lattice oxygen of V2O5 were investigated in detail. Copyright 2022 Elsevier, except certain content provided by third parties, Cookies are used by this site. Chemical looping combustion (2) Safety (2) Cross-disciplinary concepts. FBC boilers can burn fuels other than coal, and the lower temperatures of combustion (800 C / 1500 F) have other added benefits as well. Chemical modification. ACS Appl. Analytical apparatus. Rev. Minimizing excess oxygen pays an additional benefit: for a given offgas temperature, the NOx level is lowest when excess oxygen is kept lowest. Google Scholar. & Kondratenko, E. V. Evidences of the origin of N2O in the high-temperature NH3 oxidation over Pt-Rh gauze. One is through doping or lattice site substitution, in an attempt to introduce crystallographic defects that facilitate oxygen ion diffusion. Xia.W. Nat. The reduction degree of V2O5 dictates the product distribution but does not alter the catalytic NH3 oxidation activity. Chemical looping combustion (3) Safety (1) Petrochemical industry.
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