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137 results on '"Dietzel, Pascal D. C."'

1. Exploring cluster formation in Zr-MOF synthesis in situ using X-ray absorption spectroscopy.

Author

Zavorotynska, Olena, Åsland, Anna Cecilie, Dietzel, Pascal D. C., and Chavan, Sachin M.

Abstract

Metal–organic frameworks (MOFs) with a Zr-oxo cluster [(Zr6O4(OH)4)]12− are exceptionally stable and offer vast potential for a wide range of applications. Synthesis parameters strongly affect the quality, stability, morphology, etc., of the MOFs. In this study, we present an experimental set-up that allows following in situ element-specific chemical transformations during synthesis and the effect of various reaction parameters on the reaction products. Zr–fumarate formation was monitored using X-ray absorption spectroscopy (XAS) in ZrCl4–DMF-based solutions. We have studied (i) the local (∼2–5 Å) environment around Zr4+ ions in the early stages of the Zr-oxo cluster formation and MOF-synthesis reaction, (ii) kinetics of the synthesis reaction and its dependence on water and modulator concentrations, and (iii) the effect of the reaction parameters on MOF product quality. XAS data have provided direct evidence that the increased amounts of water and modulator accelerate the reaction. It has also confirmed that water is essential for MOF formation in DMF. Zr-cluster formation and the synthesis reaction were not observed in the absence of water in ZrCl4–DMF and ZrCl4–DMF-linker–modulator solutions. According to the EXAFS data, Zr4+ ions are octahedrally coordinated by chlorine atoms in anhydrous solutions with and without the linker. In contrast, the Zr-oxo clusters and MOFs were formed only in the presence of water. The results of the in situ experiments were correlated with post-synthetic characterization of the resultant MOF products. [ABSTRACT FROM AUTHOR]

Published
2024
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2. Upscaling bifunctional materials for Ca-Cu looping: fixed bed reactor tests

Author

Research Council of Norway, Grasa Adiego, Gemma [0000-0002-4242-5846], Martínez Berges, Isabel [0000-0002-2364-463X], Dietzel, Pascal D. C. [0000-0001-5731-2118], Di Felice, Luca [0000-0002-4378-6408], Westbye, Alexander, Aranda, Asunción, Grasa Adiego, Gemma, Martínez Berges, Isabel, Dietzel, Pascal D. C., Di Felice, Luca, Research Council of Norway, Grasa Adiego, Gemma [0000-0002-4242-5846], Martínez Berges, Isabel [0000-0002-2364-463X], Dietzel, Pascal D. C. [0000-0001-5731-2118], Di Felice, Luca [0000-0002-4378-6408], Westbye, Alexander, Aranda, Asunción, Grasa Adiego, Gemma, Martínez Berges, Isabel, Dietzel, Pascal D. C., and Di Felice, Luca

Abstract

Calcium-Copper Chemical Looping Technology is a hybrid concept combining Sorption-Enhanced Reforming (SER) and Chemical Looping Combustion (CLC) for hydrogen production from natural gas with integrated CO2 capture. SER involves reforming, water gas shift and CO2 capture in the same reactor vessel (reformer) making use of a CaO-based high temperature solid sorbent to capture the CO2: CH4 (g) + 2H2O (g) + CaO → CaCO3 + 4H2(g) This leads to process intensification due to avoidance of additional water gas shift steps as well as a downstream CO2 separation system, while hydrogen concentrations up to 98 vol% (dry basis) can be obtained at temperatures around 650 °C at 1 bar. To regenerate the sorbent at high temperature (900 °C, 1 bar), heat is provided via indirect heating2 or direct oxy-fuel combustion3. In the Ca-Cu Looping technology, a second Cu/CuO loop is introduced in the process and the calcination of CaCO3 is coupled and thermally sustained by the exothermic CuO reduction with H2, CO and/or CH4. In this way, expensive Air Separation Unit (ASU) or heat exchange surfaces are avoided, while fixed bed reactors are preferred to fluidized beds allowing the production of pressurized H2 without circulation of solids. Specific Energy Consumption (SPECCA) for the Ca-Cu process have been found to be in the range 1.1-1.5 MJ/kgCO2, which compares well with oxy-SER (1.6-2) and benchmark Fired Tubular Reactor / MDEA system (3.5) 4–6. The novelty proposed in this work is to combine CaO and CuO phases into one bi-functional material using relatively low-cost raw materials as well as an easy and scalable synthesis method. This configuration has the potential to a) lower the inert fraction in the reactor bed and thus limit the sensible heating requirement in the reactor, and b) to promote close contact between the CaO and CuO phases, improving the heat and mass transfer compared to a segregated particle arrangement. Mayenite, a suitable phase for increasing the stability of CaO-ba

Published
2019

3. Fixed bed reactor validation of a mayenite based combined calcium–copper material for hydrogen production through Ca–Cu Looping

Author

Research Council of Norway, Grasa Adiego, Gemma [0000-0002-4242-5846], Dietzel, Pascal D. C. [0000-0001-5731-2118], Di Felice, Luca [0000-0002-4378-6408], Westbye, Alexander, Aranda, Asunción, Grasa Adiego, Gemma, Dietzel, Pascal D. C., Martínez Berges, Isabel, Di Felice, Luca, Research Council of Norway, Grasa Adiego, Gemma [0000-0002-4242-5846], Dietzel, Pascal D. C. [0000-0001-5731-2118], Di Felice, Luca [0000-0002-4378-6408], Westbye, Alexander, Aranda, Asunción, Grasa Adiego, Gemma, Dietzel, Pascal D. C., Martínez Berges, Isabel, and Di Felice, Luca

Abstract

For the first time, a mayenite based material combining calcium and copper (18.0/37.6/44.4 estimated active wt % CaO/CuO/Ca12Al14O33, CuO/CaO = 2.1 [wt/wt]) has been subjected to three full calcium–copper chemical looping combustion (Ca–Cu Looping) cycles in a fixed bed reactor (70.0 g of combined material and 3.5 g of 18.0 wt % Ni/Al2O3 reforming catalyst), demonstrating the feasibility of a combined materials approach to hydrogen production through Ca–Cu Looping. Combined materials were characterized by helium pycnometry, mercury intrusion, nitrogen adsorption, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and energy dispersive X-ray diffraction before and after reactor testing. A carbon dioxide capture capacity of 14.6–15.0 g CO2/100 g (640–660 °C, 1.0 MPa, 2.5 kgCH4 kgcat–1 h–1), full oxidation, and expected calcination efficiencies (51–64%) were obtained. Combined material performance is comparable to that of segregated materials previously tested in the same experimental rig. Process intensification of Ca–Cu Looping through combined materials development is promising.

Published
2019

4. Upscaling bifunctional materials for Ca-Cu looping: fixed bed reactor tests

Author

Westbye, Alexander, Aranda, Asunción, Grasa Adiego, Gemma, Martínez Berges, Isabel, Dietzel, Pascal D. C., Di Felice, Luca, Research Council of Norway, Grasa Adiego, Gemma, Martínez Berges, Isabel, Dietzel, Pascal D. C., Di Felice, Luca, Grasa Adiego, Gemma [0000-0002-4242-5846], Martínez Berges, Isabel [0000-0002-2364-463X], Dietzel, Pascal D. C. [0000-0001-5731-2118], and Di Felice, Luca [0000-0002-4378-6408]

Subjects
Pre-combustion capture, CCS and hydrogen combinations
Abstract

Poster presented at the 10th "Trondheim Conference on CO2 Capture, Transport and Storage", June 17 - 19, 2019, in Trondheim - Norway., Calcium-Copper Chemical Looping Technology is a hybrid concept combining Sorption-Enhanced Reforming (SER) and Chemical Looping Combustion (CLC) for hydrogen production from natural gas with integrated CO2 capture. SER involves reforming, water gas shift and CO2 capture in the same reactor vessel (reformer) making use of a CaO-based high temperature solid sorbent to capture the CO2: CH4 (g) + 2H2O (g) + CaO → CaCO3 + 4H2(g) This leads to process intensification due to avoidance of additional water gas shift steps as well as a downstream CO2 separation system, while hydrogen concentrations up to 98 vol% (dry basis) can be obtained at temperatures around 650 °C at 1 bar. To regenerate the sorbent at high temperature (900 °C, 1 bar), heat is provided via indirect heating2 or direct oxy-fuel combustion3. In the Ca-Cu Looping technology, a second Cu/CuO loop is introduced in the process and the calcination of CaCO3 is coupled and thermally sustained by the exothermic CuO reduction with H2, CO and/or CH4. In this way, expensive Air Separation Unit (ASU) or heat exchange surfaces are avoided, while fixed bed reactors are preferred to fluidized beds allowing the production of pressurized H2 without circulation of solids. Specific Energy Consumption (SPECCA) for the Ca-Cu process have been found to be in the range 1.1-1.5 MJ/kgCO2, which compares well with oxy-SER (1.6-2) and benchmark Fired Tubular Reactor / MDEA system (3.5) 4–6. The novelty proposed in this work is to combine CaO and CuO phases into one bi-functional material using relatively low-cost raw materials as well as an easy and scalable synthesis method. This configuration has the potential to a) lower the inert fraction in the reactor bed and thus limit the sensible heating requirement in the reactor, and b) to promote close contact between the CaO and CuO phases, improving the heat and mass transfer compared to a segregated particle arrangement. Mayenite, a suitable phase for increasing the stability of CaO-based synthetic sorbents7, has been used to support the Ca-Cu combined materials. In a previous work, the effect of the CuO precursors (Cu(OH)2, Cu(NO3)2 and CuO mesh powder), and the CuO-CaO loading (at constant weight ration of 2) on the hydrothermal synthesis of combined powder has been investigated in TGA for about 40 carbonation-calcination and oxidation-reduction cycles. This study has shown that 40 wt% CuO materials are stable for 40 TGA cycles while all investigated 50 wt% CuO materials deactivate, regardless of CuO precursor 8. Subsequently, the synthesis method has been upscaled to produce 100g of powders which have been agglomerated to particles with 0.5 – 0.8 mm diameter, and subjected to 40 carbonation-oxidation-reduction-calcination cycles in TGA. The agglomerates of the combined Cu(OH)2 prepared powder are stable for 40 TGA cycles, although suffer from an initial 25 wt% capacity reduction in both O2 and CO2 capacities relative to the Cu(OH)2 powder. Finally, the combined material agglomerates have been mixed with a commercial reforming catalyst and tested in a lab scale fixed bed reactor along the three main reaction stages of a Ca-Cu looping process – SER, Cu oxidation and Cu reduction. Operation conditions chosen for the process stages were representative for the scaling up of the process in terms of pressure, gas spatial velocities and gas composition. The obtained evolution of product gas composition with time, as well as the temperature profiles within the bed along each reaction stage during three complete cycles (as depicted in Figure 1 for the SER step) has validated the combined materials concept at lab scale, and shows promises in terms of increased amount of active material per reactor volume., This work is funded by the Research Council of Norway in the framework of CLIMIT-prosjekt 254736Ca-Cu Cycles

Published
2019

7. Effect of larger pore size on the sorption properties of isoreticular metal-organic frameworks with high number of open metal sites

Author

Dietzel, Pascal D. C., Georgiev, Peter A., Frøseth, Morten, Johnsen, Rune E., Fjellvåg, Helmer, Blom, Richard, Dietzel, Pascal D. C., Georgiev, Peter A., Frøseth, Morten, Johnsen, Rune E., Fjellvåg, Helmer, and Blom, Richard

Abstract

We show that four isostructural CPO-54-M metal-organic frameworks based on the larger organic linker 1,5-dihydroxynaphthalene-2,6-dicarboxylic acid and divalent cations (M = Mn, Mg, Ni, Co) are isoreticular to the CPO-27 (MOF-74) materials. Desolvated CPO-54-Mn contains a very high concentration of open metal sites, which has a pronounced effect on the gas adsorption of N 2 , H 2 , CO 2 and CO. Initial enthalpies of adsorption are significantly higher than for MOFs without open metal sites and are slightly higher than for CPO-27. The plateau of high enthalpy of adsorption decreases earlier in CPO-54-Mn as a function of loading per mole than in CPO-27-Mn. Cluster and periodic Density Functional Theory based calculations of the adsorbate structures and energetics show that the larger adsorption energy at low loadings, when only open metal sites are occupied, is mainly due to larger contribution of dispersive interactions for the materials with the larger, more electron rich bridging ligand.

Published
2020

12. Electrospray Mass Spectrometry Investigation into the Formation of CPO-27

Author

Rosnes, Mali H., Mathieson, Jennifer S., Törnroos, Karl W., Johnsen, Rune E., Cronin, Leroy, Dietzel, Pascal D. C., Rosnes, Mali H., Mathieson, Jennifer S., Törnroos, Karl W., Johnsen, Rune E., Cronin, Leroy, and Dietzel, Pascal D. C.

Abstract

Electrospray ionization mass spectrometry (ESI-MS) has been utilized to investigate the self-assembly processes occurring during the formation of the microporous metal–organic framework CPO-27-M (M = Co, Ni). The mono- and dinuclear building units {M(Hxdhtp)} and {M2(Hxdhtp)}, where Hxdhtp is the organic linker HxC8O6 and fragments thereof, were identified as key species present in the reaction mixture during the product formation. Time-resolved powder X-ray diffraction analysis was used to follow the synthesis and confirmed that no other crystalline products occur in the reaction mixture prior to the crystallization of CPO-27-Ni. When equimolar reactions were performed at room temperature, compounds [(M(H2dhtp)(H2O)4·2H2O] (M = Co, Ni) crystallized instead of CPO-27 obtained at the higher temperature of the solvothermal procedure. It was confirmed that mono- and dinuclear species are key building blocks not only in the formation of CPO-27-M but also in the formation of the 1D chain structure (M(H2dhtp)(H2O)4) obtained from these room-temperature reactions.

Published
2019

15. Variability in the Formation and Framework Polymorphism of Metal‐organic Frameworks based on Yttrium(III) and the Bifunctional Organic Linker 2,5‐Dihydroxyterephthalic Acid.

Author

Dietzel, Pascal D. C., Blom, Richard, and Fjellvåg, Helmer

Subjects
*METAL-organic frameworks, *FIRST-order phase transitions, *YTTRIUM, *ORGANIC conductors, *X-ray powder diffraction, *STRUCTURAL frames
Abstract

Depending on the solvothermal reaction conditions, we obtained three different metal‐organic frameworks with yttrium(III) as metal component and 2,5‐dihdyroxyterepthalic acid (H4dhtp) as bifunctional organic linker: Y2(H2dhtp)3(dmf)4·(dmf)2 (CPO‐29) contains dinuclear, paddle‐wheel like inorganic secondary building units (SBUs) connected by the organic linker to a network with α‐Po topology, while Y2(H2dhtp)(dhtp)(dmf)2 (CPO‐30) and Y2(H2dhtp)(dhtp)(dmf)2(H2O)2·(H2O)4 (CPO‐31) contain one‐dimensional inorganic SBUs that differ in how the half‐ and fully deprotonated ligands are connected to and arranged around them. Only the carboxylic acid groups of the organic linker are deprotonated in CPO‐29, while CPO‐30 and CPO‐31 contain both 2,5‐dihydroxyterephthalate (H2dhtp2–) linkers and fully deprotonated 2,5‐dioxidoterephthalate (dhtp4–) linkers. All three compounds contain large volumes filled with solvent, but we were able to demonstrate permanence of porosity only for CPO‐30. Variable temperature powder X‐ray diffraction reveals that CPO‐29 and CPO‐31 undergo discontinuous phase transitions upon heating, and the flexibility of the framework structure indicated by these might be the reason for the inability to access the pore volume. Desolvated CPO‐30 and CPO‐31 are polymorphs, whose network structures differ in whether the H2dhtp2– and dhtp4– linkers are located in cis or trans arrangement around the inorganic SBU. [ABSTRACT FROM AUTHOR]

Published
2021
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23. A Permanently Porous Yttrium–Organic Framework Based on an Extended Tridentate Phosphine Containing Linker

Author

Bezrukov, Andrey A. and Dietzel, Pascal D. C.

Abstract

The metal–organic framework [Y(tbpp)]·nDMF (1) was synthesized from yttrium(III) nitrate and the tritopic linker tris(4′-carboxy[1,1′-biphenyl]-4-yl)phosphine (H3tbpp). The distance between the coordinating atoms of the carboxylate groups of the extended tridentate phosphine linker is more than 1.8 nm, resulting in an average pore dimension of 0.9 nm in the noninterpenetrated metal–organic framework. The material exhibits high thermal stability and permanent porosity after removal of guest molecules from the one-dimensional pore system. The desolvated compound adsorbs nitrogen, argon, hydrogen, and carbon dioxide. Favorable adsorption of CO2over N2is predicted using ideal adsorbed solution theory (IAST). The isosteric enthalpies of adsorption of H2and CO2of −7 and −22 kJ mol–1, respectively, are representative for metal−organic frameworks with no accessible strong host–guest binding sites, despite the bifunctional nature of the organic ligand. The absence of strong specific adsorption sites was confirmed by in situ powder synchrotron X-ray diffraction of the reversible isobaric CO2sorption process. Analysis of the diffraction data indicates that the CO2molecules in the pores are disordered and nonlocalized. Despite this, it was possible to quantify the evolution of the occupation of the pores. CO2is adsorbed at an approximately constant below 320 K from 10% loading to full capacity at 195 K.

Published
2024
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28. Incorporation of an intact dimeric Zr12 oxo cluster from a molecular precursor in a new zirconium metal–organic framework.

Author

Bezrukov, Andrey A., Törnroos, Karl W., Le Roux, Erwan, and Dietzel, Pascal D. C.

Subjects
ZIRCONIUM metallurgy, METAL-organic frameworks, CHEMICAL stability, CARBOXYLATE derivatives, HYDROXYL group analysis, MONOCARBOXYLATE transporters
Abstract

Two zirconium–organic frameworks were synthesized by exchanging the acetate ligands in [Zr12O8(OH)8(CH3COO)24] with polydentate linkers. Partial substitution of acetate groups by a phosphine based linker yielded a new porous framework with this unique dimeric Zr12 cluster unit as molecular building block. More exhaustive substitution of acetate resulted in cleavage of the Zr12 unit and formation of UiO-67. [ABSTRACT FROM AUTHOR]

Published
2018
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34. Open Metal Sites in the Metal–Organic Framework CPO-27-Cu: Detection of Regular and Defect Copper Species by CO and NO Probe Molecules

Author

Drenchev, Nikola, Rosnes, Mali H., Dietzel, Pascal D. C., Albinati, Alberto, Hadjiivanov, Konstantin, and Georgiev, Peter A.

Abstract

The open copper metal sites in CPO-27-Cu were studied by means of IR spectroscopy of adsorbed CO and NO, and density functional theory calculations. Very low Lewis acidity of the Cu2+sites was established by CO (IR band at 2153–2149 cm–1). Variable-temperature IR experiments indicate adsorption enthalpy of ca. −20 kJ mol–1. It was also found that CO is a sensitive probe of the occupation of the neighboring copper sites. In contrast to the general expectations, NO is very weakly adsorbed on the Cu2+sites (−14.5 kJ mol–1, IR band at 1888 cm–1). The effect is attributed to the particular Cu2+ion coordination and electronic state, leading to a large Jan–Teller deformation and low effective charge, preventing significant charge transfer effects between the metal center and the guest molecules as well as any significant electrostatic interactions. Thus, dominating are van der Waals interactions which position the adsorbed molecule relatively far away at about 2.7–3.0 Å. Adsorption of CO also revealed that a small fraction of the copper ions are found in the Cu+state (IR band at 2120 cm–1), and these sites were associated with and modeled as defect undercoordinated sites most probably located at the terminal crystallite surfaces. A small fraction of adsorbed NO was relatively strongly adsorbed (−35 kJ mol–1) and associated with the same set of defect copper sites.

Published
2018
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36. Crystal structure of dimethyl 4,4'-dimethoxy-biphenyl-3,3'-dicarboxylate.

Author

Lundvall, Fredrik, Dietzel, Pascal D. C., and Fjellvåg, Helmer

Subjects
*CRYSTAL structure, *CARBOXYLATE derivatives, *RING formation (Chemistry)
Abstract

In the title compound, C18H18O6, the benzene rings are coplanar due to the centrosymmetric nature of the molecule, with an inversion centre located at the midpoint of the C-C bond between the two rings. Consequently, the methyl carboxylate substituents are oriented in a trans fashion with regards to the bond between the benzene rings. The methyl carboxylate and methoxy substituents are rotated slightly out of plane relative to their parent benzene rings, with dihedral and torsion angles of 18.52 (8) and -5.22 (15)°, respectively. The shortest O·H contact between neighbouring molecules is about 2.5 Å. Although some structure-directing contributions from C-H···O hydrogenbonding interactions are possible, the crystal packing seems primarily directed by weak van der Waals forces. [ABSTRACT FROM AUTHOR]

Published
2016
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38. Methane storage on CPO-27-Ni pellets

Author

Tagliabue, Marco, primary, Rizzo, Caterina, additional, Millini, Roberto, additional, Dietzel, Pascal D. C., additional, Blom, Richard, additional, and Zanardi, Stefano, additional

Published
2010
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42. Response of CPO-27-Ni towards CO, N2 and C2H4

Author

Chavan, Sachin, primary, Bonino, Francesca, additional, Vitillo, Jenny G., additional, Groppo, Elena, additional, Lamberti, Carlo, additional, Dietzel, Pascal D. C., additional, Zecchina, Adriano, additional, and Bordiga, Silvia, additional

Published
2009
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