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  • 1. Abbas, Sk Jahir
    et al.
    Ramacharyulu, P. V. R. K.
    Lo, Hsin-Hsi
    Ali, Sk Imran
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ke, Shyue-Chu
    A catalytic approach to synthesis of PLP analogs and other environmental protocols in a single handed CaO/TiO2 green nanoparticle2017In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 210, p. 276-289Article in journal (Refereed)
    Abstract [en]

    As our precursory stage we have focus straight forward on clean catalytic approach for the production of C3 substituted pyridoxal-5 '-phosphate analogues of vitamin B6, and other environmental protocols like photocatalytic activity, green fossil fuels and c-c coupling using efficient biocompatible eggshell related unrivalled materials which show versatility of the catalytic effect on different inorganic support. The eggshell immobilized nanoparticles have encouraging relevance in creation of new molecules and can advantageously be studied by various spectroscopic, thermal and elemental analyses like powder X-ray diffraction (XRD), Raman spectroscopy, UV-vis, Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) surface area analysis. The elucidate nature of nanoparticles offer: more active site acts as lewis acid, vacancies on the catalyst surface and good to better yield of C3 substituted deoxy and 2-nor deoxy coenzyme pyridoxine (PN), coupling products propargylamines (PA), photo degrading enhancement of MB and nucleophilic substituted fatty acid (BD). This enzyme cofactor explore molecular synthons to synthetic equivalent: 3-deoxy and 2-nor-3-deoxy pyridoxal (PL), pyridoxal oxime (P0), pyridoxamine (PM) and mono phosphate derivative of 3-deoxyPM, 3-deoxyPL respectively and chemistry of selective oxidation and schiff base mechanism was studied and complemented through combined experimental and theoretical molecular orbital calculation consequently. The heterogeneous catalyst has strong selective ability towards selective reducing pyridine diester, bioactive intermediates substances and holds vast potential towards separation for the photogenerated electron-hole pairs and renewable, nontoxic, biodegradable green fossil fuels. The catalyst including environmental concern is reapplicable and strong impressive that can unfold the space of worthy metal component widely and facilitate the scope to take a vital role in different fileds like catalysis, biochemistry, nanoscience, energy and materials science.

  • 2. Bello, Estefania
    et al.
    Ferri, Pau
    Nero, Mathias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Willhammar, Tom
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Millet, Isabel
    Schütze, Frank W.
    van Tendeloo, Leen
    Vennestrøm, Peter N. R.
    Boronat, Mercedes
    Corma, Avelino
    Moliner, Manuel
    NH3-SCR catalysts for heavy-duty diesel vehicles: Preparation of CHA-type zeolites with low-cost templates2022In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 303, article id 120928Article in journal (Refereed)
    Abstract [en]

    Computer-assistance allows selecting the most adequate low-cost organic structure directing agents (OSDAs) for the crystallization of Al-rich CHA-type zeolites. The host-guest stabilization energies of tetraethylammonium (TEA), methyltriethylammonium (MTEA) and dimethyldiethylammonium (DMDEA), in combination with Na, were first theoretically evaluated. This ab-initio analysis reveals that two TEA show a serious steric hindrance in a cha cavity, whereas two MTEA would present excellent host-guest confinements. The synthesis of Al-rich CHA-type zeolites has been accomplished using TEA and MTEA. Electron diffraction and high-resolution transmission electron microscopy reveal large CHA-domains with narrow faulted GME-domains in the CHAtype material synthesized with TEA, confirming the better OSDA-directing roles of MTEA cations towards the cha cavity, in good agreement with DFT calculations. Cu-exchanged Al-rich CHA-type samples achieved with MTEA and TEA show excellent catalytic activity and hydrothermal stability for the selective catalytic reduction (SCR) of NOx with ammonia under conditions relevant for future heavy duty diesel conditions.

  • 3.
    Cui, D.
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Low, J.
    Rondinella, V. V.
    Spahiu, K.
    Hydrogen catalytic effects of nanostructured alloy particles in spent fuel on radionuclide immobilization2010In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 94, no 02-jan, p. 173-178Article in journal (Refereed)
    Abstract [en]

    For the first time, hydrogen catalytic effects of fission product alloy particles nondestructively extracted from spent nuclear fuel were demonstrated. The redox sensitive radionuclides at oxidized forms Se(IV), Tc(VII), U(VI), Np(V) and Pu(VI) were found to be stable in a solution saturated with a gas mixture (Ar + 10% H-2 + 0.03% CO2) but rapidly immobilized in the same solution when contacted with the particles. In comparison, a synthetic alloy sample with similar elemental composition as the alloy particles generated in nuclear fuel displayed a smaller, but unequivocal catalytic effect. The smaller catalytic effect of synthetic alloy was apparently enhanced by a P-radiation source. The information obtained in this work contributes to improved understanding of the redox chemistry of radionuclides in nuclear waste geologic repository environments and, in particular, of the catalytic properties of these unique alloy particles.

  • 4. Granlund, Moa Z.
    et al.
    Jansson, Kjell
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nilsson, Marita
    Dawody, Jazaer
    Pettersson, Lars J.
    Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel2014In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 154, p. 386-394Article in journal (Refereed)
    Abstract [en]

    The objective of this paper was to study the influence three promoters (Co, La, Mn) had on the catalytic activity of Rh-based catalysts for autothermal reforming of diesel. The catalysts were supported on CeO2ZrO2 and the loading was 1 wt.% Rh and 6 wt.% promoter. The catalytic activity was evaluated in a monolith bench scale reactor with Swedish Environmental diesel, MK1. The process parameters employed at the ATR experiments were; O-2/C similar to 0.45, H2O/C similar to 2.5 and GHSV similar to 50,000h(-1), meanwhile the reactor temperature was ramped from 700 degrees C to 950 degrees C. The catalysts were compared based on their fuel conversion, H-2 yield and the selectivity of different short-chain hydrocarbons. The results showed that all three catalysts had both high fuel conversion and H-2 yield in the optimal ATR operation temperatures. The H-2 yield and fuel conversion were increasing in the order Rh/Mn, Rh/La, Rh/Co. To get further insight in the difference between the materials the fresh and aged catalytic materials were characterized. The characterization methods used were H-2-temperature programmed reduction (H-2-TPR), powder X-ray diffraction (XRD), and BET surface measurements. The BET surface measurements showed that promotion with La gave improved thermal stability of the material. The XRD showed a high dispersion of all metals except Co, which was present as crystals in the size range of the particles of the support.

  • 5. Granlund, Moa Z.
    et al.
    Jansson, Kjell
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nilsson, Marita
    Dawody, Jazaer
    Pettersson, Lars J.
    Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel: Aging and characterization2015In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 172, p. 145-153Article in journal (Refereed)
    Abstract [en]

    In this study, three bimetallic catalysts are evaluated for autothermal reforming (AIR) of fuels (1 wt.% Rh and 6 wt.% X (X= Co, La or Mn) supported on high-surface area CeO2-ZrO2). The catalysts are aged for approximately 35 h and carefully characterized both as fresh and aged materials. The objective is to illuminate the changes in material properties after time on stream as well as the differences among the materials. The changes in material properties are evaluated by H-2-TPR, BET surface area analysis, TEM, SEM, and STEM. The material's tendency to coke is investigated by TPO analysis. The three materials exhibit promising initial activity. However, the Co-promoted sample decreases sharply in activity after 25 h of operation. Meanwhile, the other two materials display a more stable activity throughout the evaluated time. The deactivation of the Co-promoted material could be linked to the high amount of coke deposited during operation. Based on the results from the activity evaluation and characterization, the material promoted with lanthanum displays the most promising results. The addition of lanthanum resulted in a catalyst that was both stable and had high activity, even though a low rhodium loading is used. The material also shows superior thermal resistance compared to the other two materials. In addition, the tendency to coke is significantly lower compered to the other materials, which is especially beneficial when dealing with AIR of complex fuels.

  • 6. Jiraroj, Duangkamon
    et al.
    Jirarattanapochai, Orhathai
    Anutrasakda, Wipark
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Chulalongkorn University, Thailand.
    Tungasmita, Duangamol N.
    Selective decarboxylation of biobased fatty acids using a Ni-FSM-16 catalyst2021In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 291, article id 120050Article in journal (Refereed)
    Abstract [en]

    A novel catalyst based on nickel supported on a folded sheet material (FSM) was synthesized and fully characterized. The resulting Ni-FSM-16 catalyst showed a high reactivity and selectivity in decarboxylation of plant-based carboxylic acids to yield the corresponding linear alkenes and alkanes in up to 75 % yield and less than 5 % of undesired cracking products. In addition, lignin-derived vanillic acid was smoothly converted to guaiacol. A comparative investigation showed that both the support and the metal of the Ni-FSM-16 catalyst proved to be pivotal for the reactivity. Particularly, substituting Ni with Fe, Pd or Al or replacing the FSM-16 support with MCM-41 or SBA-15 led to lower reactivity and selectivity towards linear decarboxylated products. The superior catalytic performance of Ni-FSM-16 was driven by a higher and more even metal distribution, more acidic silanol-group and an electron-rich, thus softer Ni, that promote coordination by the carbon-carbon double-bond of the fatty acid.

  • 7. Karatzas, Xanthias
    et al.
    Jansson, Kjell
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Gonzalez, Angelica
    Dawody, Jazaer
    Pettersson, Lars J.
    Autothermal reforming of low-sulfur diesel over bimetallic RhPt supported on Al(2)O(3), CeO(2)-ZrO(2), SiO(2) and TiO(2)2011In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 106, no 3-4, p. 476-487Article in journal (Refereed)
    Abstract [en]

    The objective of this paper is to study and clarify the role of selected supports (both reducible and non-reducible) on the activity, selectivity and stability of RhPt-based catalyst for diesel reforming. Autothermal reforming (AIR) of low-sulfur diesel (S similar to 6 ppm, C/H similar to 6.43 (w/w)), H(2)O/C similar to 2.5, O(2)/C similar to 0.49, was tested at bench scale to detect differences in activity for catalysts consisting of 1 wt% Rh and 1 wt% Pt supported on alumina, ceria-zirconia (17.5 wt% ceria), silica and titania. Promoters in the form of MgO. Y(2)O(3), La(2)O(3), CeO(2) and ZrO(2), ranging from 4 wt% to 10 wt%, were also added onto the supports to detect differences in catalyst activity in terms of diesel conversion, CO(2) selectivity, and hydrogen and ethylene production. All metals were added sequentially onto the support by the incipient wetness technique and washcoated on 400 cpsi cordierite monolithic carriers with dimensions d = 17.8 mm, l=30.5 mm. The product gas analysis, using FTIR and NDIR, showed that RhPt/CeO(2)-ZrO(2) was found to be most active for AIR of diesel since a fuel conversion close to 98% was obtained. Furthermore, the catalyst activity of the unpromoted samples, in terms of diesel conversion, increased in the following order: RhPt/SiO(2) < RhPt/TiO(2) < RhPt/Al(2)O(3) < RhPt/CeO(2)-ZrO(2). The addition of promoters was found to be insignificant as well as having a negative impact on the catalyst performance in most cases, except for the alumina-promoted sample. The addition of 10 wt% La(2)O(3) on RhPt/Al(2)O(3) was found to enhance diesel conversion, hydrogen productivity as well as lower the ethylene concentration from 3700 ppm to less than half that value. The latter observation was confirmed by O(2)-TPO analysis of aged powder samples where lower loads of coke were present than on the La-promoted sample. The morphology, surface and bulk properties of RhPt/CeO(2)-ZrO(2) were closely examined in order to provide a possible correlation between the activity and characterization results. N(2)-BET analysis showed that the surface area of RhPt/CeO(2)-ZrO(2) was 64 m(2)/g, while the silica samples exhibited the highest area, similar to 137-185 m(2)/g. Hence, the difference in the surface areas was not enough to explain the trends observed in the activity measurements. XRD analysis of RhPt/CeO(2)-ZrO(2) showed crystalline phases characteristic of zirconia, most likely tetragonal. Also, the diffractogram did not reveal any Rh or Pt peaks indicating that the noble metal particles are highly dispersed on the support. In contrast, peaks ascribed to metallic Pt (similar to 30-46 nm) were clearly visible on the XRD patterns taken from all the other supported samples. H(2)-TPR analysis of RhPt/CeO(2)-ZrO(2) showed reduction peaks ascribed to Rh(i)O(x) species as well as a minor hydrogen spillover effect on the support to be present at T=120 degrees C and 450 degrees C, respectively. Also, the hydrogen consumption of the Rh(i)O(x) species was the highest compared to the other supported RhPt samples. TEM analysis performed on fresh RhPt/CeO(2)-ZrO(2) showed that the Rh(i)O(x) and Pt particles were highly dispersed on the support, both with particle sizes in the vicinity of similar to 5-15 nm. Rh species was found on ceria and zirconia, while Pt was present mainly on the ceria layer possibly in the form of Pt-O-Ce bonds. H(2)-chemisorption analysis measured at T similar to 40 degrees C shows similar Rh dispersion results. To summarize, the higher activity results of RhPt/CeO(2)-ZrO(2) for AIR of diesel, compared to other supported catalysts, may be ascribed to the higher reducibility of Rh(i)O(x) species as well as the superior Rh and Pt dispersion. Also, the support contribution, in particular ceria, is believed to promote water gas-shift activities as well as reduce coke deposits on the catalyst surface.

  • 8. Ni, Yueran
    et al.
    He, Bowen
    Luo, Siyuan
    Wu, Xiaoyong
    Feng, Xuezhen
    Luo, Yi
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Lin, Jia
    Sun, Junliang
    Fan, Ke
    Ji, Yongfe
    Zhang, Gaoke
    Chen, Hong
    Microporous core-shell Co-11(HPO3)(8)(OH)(6)/Co-11(PO3)(8)O-6 nanowires for highly efficient electrocatalytic oxygen evolution reaction2019In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 259, article id 118091Article in journal (Refereed)
    Abstract [en]

    Exploring high-efficient oxygen evolution reaction (OER) catalysts is critical for producing clean H-2 fuel through water splitting. Co and P involved Co-Pi and cobalt phosphide OER catalysts attracted tremendous attention, while limited report on cobalt phosphite as an OER catalyst. Herein, a novel cobalt phosphite nanowires with microporous 1D channel have been succsessfully discovered with remarkable catalytic performance of a low overpotential of (similar to)340 mV and Tafel slope of 60 mV dec(-1) at 10 mA cm(-2) at pH 14. Through comprehensive structural characterization, the effective species has been clearly illustrated to be the in-situ formed heterostructural Co-11(HPO3)(8)(OH)(6)/Co-11(PO3)(8)O-6 core-shell structure nanowires. This work fills the gap for exploring high efficient cobalt phosphites OER catalysts under akaline condition and paves the way for exploring novel high efficiency waster splitting catalysts.

  • 9. Nilsson, Marita
    et al.
    Jansson, Kjell
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Jozsa, Peter
    Pettersson, Lars J.
    Catalytic properties of Pd supported on ZnO/ZnAl2O4/Al2O3 mixtures in dimethyl ether autothermal reforming2009In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 86, no 02-jan, p. 18-26Article in journal (Refereed)
    Abstract [en]

    The catalytic properties of Pd supported on mixtures of zinc oxide, zinc aluminate, and alumina, prepared from gamma-alumina and zinc nitrate, were studied for autothermal reforming (ATR) of dimethyl ether (DME). The performance of the catalysts was tested in a small-scale reactor, using cordierite monoliths as substrate. The catalysts exhibited high activity and generated hydrogen-rich product gases with CO concentrations below 5 vol.% in the temperature range between 350 and 450 degrees C (at O-2:DME = 0.7, H2O:DME = 2.5, and GHSV = 15000 h(-1)). The highest DME conversion was obtained for a catalyst in which the support comprised mainly ZnAl2O4. Physical mixing of the catalysts with gamma-Al2O3 resulted in increased DME conversion but a lowering of the CO2 selectivity. The catalysts were characterized by CO chemisorption, liquid nitrogen adsorption, temperature-programmed desorption of ammonia, temperature-programmed reduction, transmission electron microscopy, and X-ray diffraction. It was found that decreasing surface area and decreasing number of acid sites, caused by thermal treatment during generation of the supports, did not affect the activity negatively. The high CO2 selectivity of the catalysts was correlated with PdZn alloy formation. 

  • 10. Sheng, Xia
    et al.
    Li, Yuanyuan
    Yang, Taimin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Timmer, Brian J. J.
    Willhammar, Tom
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cheung, Ocean
    Li, Lin
    Brett, Calvin J.
    Roth, Stephan V.
    Zhang, Biaobiao
    Fan, Lizhou
    Guo, Yaxiao
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Berglund, Lars
    Sun, Licheng
    Hierarchical micro-reactor as electrodes for water splitting by metal rod tipped carbon nanocapsule self-assembly in carbonized wood2020In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 264, article id 118536Article in journal (Refereed)
    Abstract [en]

    Materials design of efficient electrochemical micro-reactors is challenging, although hierarchically structured, self-standing electrodes with catalyst arrays offer promise. Herein, catalyst function in compact micro-reactor electrodes is designed by nanostructural tailoring of carbonized wood for efficient water splitting. Specifically, NiFe rod tipped, N-doped graphitic carbon nanocapsule arrays are self-assembled in hierarchical wood, and the benefit of this unique presentation and its promotive effect on accessibility of the catalyst surfaces is apparent. This report also comprises the first wood based micro-reactor electrodes for electrocatalytic water oxidation demonstrating excellent performance. The overpotential for oxygen evolution reaction was as low as 180 mV for 10 mA cm(-2) current density and TOFredox was high at a level of 5.8 s(-1) (at 370 mV overpotential). This hierarchical electrode can also work as bifunctional catalyst (both as anodic and as cathodic electrode) for total water splitting with a cell potential of 1.49 V for 10 mA cm(-2) in alkaline solution, suggestive of their potential also in other electrochemical applications.

  • 11. Sun, Ya-Nan
    et al.
    Yang, Jinqin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ding, Xuesong
    Ji, Wenyan
    Jaworski, Aleksander
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Han, Bao-Hang
    Synergetic contribution of nitrogen and fluorine species in porous carbons as metal-free and bifunctional oxygen electrocatalysts for zinc-air batteries2021In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 297, article id 120448Article in journal (Refereed)
    Abstract [en]

    High-efficient bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are critical to the practical application of zinc–air batteries. Herein, a comprehensive investigation on the synergetic contribution of nitrogen (N) and fluorine (F) species in porous carbon for ORR/OER catalyses is firstly conducted. The metal-free N, F co-doped porous carbon (NFPC) possesses appealing catalytic activities in zinc–air batteries and is superior to many other catalysts. Combined with the careful exploration of N and F dopants, seventeen optimized carbon cluster structures with all possible co-doping of N and F species are considered for density functional theory calculations. It can be inferred that the F doping with graphitic and pyridinic N triggers active paramagnetic centers. The co-doping of covalent F and graphitic N especially gives the lowest free energy barrier for both ORR/OER, which could account for the notable performance of NFPC catalysts in zinc–air batteries.

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