Analysis of CCCma Radiative Transfer Calculations for Low‐Level Overcast Liquid Clouds Over ARM SGP and ENA Sites
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Brendecke, Jordann↗
Engineering topics
Li, Jiangnan
Publications and source records attributed to Li, Jiangnan.
A Flexible Phosphonate Metal–Organic Framework for Enhanced Cooperative Ammonia Capture
Not provided.
Chemistry↗
Direct Conversion of Methane to Ethylene and Acetylene over an Iron-Based Metal–Organic Framework
Conversion of methane (CH 4 ) to ethylene (C 2 H 4 ) and/or acetylene (C 2 H 2 ) enables routes to a wide range of products directly from natural gas. However, high reaction temperatures and pressures are often required to activate and convert CH 4 controllably, and separating C 2+ products from unreacted CH 4 can be challenging. Here, we report the direct conversion of CH 4 to C 2 H 4 and C 2 H 2 driven by non-thermal plasma under ambient (25 °C and 1 atm) and flow conditions over a metal–organic framework material, MFM-300(Fe). The selectivity for the formation of C 2 H 4 and C 2 H 2 reaches 96% with a high time yield of 334 μmol g cat –1 h –1 . At a conversion of 10%, the selectivity to C 2+ hydrocarbons and time yield exceed 98% and 2056 μmol g cat –1 h –1 , respectively, representing a new benchmark for conversion of CH 4 . In situ neutron powder diffraction, inelastic neutron scattering and solid-state nuclear magnetic resonance, electron paramagnetic resonance (EPR), and diffuse reflectance infrared Fourier transform spectroscopies, coupled with modeling studies, reveal the crucial role of Fe–O(H)–Fe sites in activating CH 4 and stabilizing reaction intermediates via the formation of an Fe–O(CH 3 )–Fe adduct. In addition, a cascade fixed-bed system has been developed to achieve online separation of C 2 H 4 and C 2 H 2 from unreacted CH 4 for direct use. Integrating the processes of CH 4 activation, conversion, and product separation within one system opens a new avenue for natural gas utility, bridging the gap between fundamental studies and practical applications in this area.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Modulation of Uptake and Reactivity of Nitrogen Dioxide in Metal-Organic Framework Materials
We report the modulation of reactivity of nitrogen dioxide (NO 2 ) in a charged metal–organic framework (MOF) material, MFM-305-CH 3 in which unbound N-centres are methylated and the cationic charge counter-balanced by Cl - ions in the pores. Uptake of NO 2 into MFM-305-CH 3 leads to reaction between NO 2 and Cl - to give nitrosyl chloride (NOCl) and NO 3 - anions. A high dynamic uptake of 6.58 mmol g -1 at 298 K is observed for MFM-305-CH 3 as measured using a flow of 500 ppm NO 2 in He. In contrast, the analogous neutral material, MFM-305, shows a much lower uptake of 2.38 mmol g -1 . The binding domains and reactivity of adsorbed NO 2 molecules within MFM-305-CH 3 and MFM-305 have been probed using in situ synchrotron X-ray diffraction, inelastic neutron scattering and by electron paramagnetic resonance, high-field solid-state nuclear magnetic resonance and UV/Vis spectroscopies. The design of charged porous sorbents provides a new platform to control the reactivity of corrosive air pollutants.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Synthesis of Nitro Compounds from Nitrogen Dioxide Captured in a Metal-Organic Framework
Increasing levels of air pollution are driving the need for the development of new processes that take “waste-to-chemicals”. Herein, we report the capture and conversion under ambient conditions of a major air pollutant, NO 2 , using a robust metal-organic framework (MOF) material, Zr-bptc (H 4 bptc = 3,3',5,5'-biphenyltetracarboxylic acid), comprising {Zr 6 (μ 3 -O) 4 (μ 3 -OH) 4 (COO) 12 } clusters linked by 4-connected bptc 4– ligands in an ftw topology. At 298 K, Zr-bptc shows exceptional stability and adsorption of NO 2 at both low (4.9 mmol g –1 at 10 mbar) and high pressures (13.8 mmol g –1 at 1.0 bar), as measured by isotherm experiments. Dynamic breakthrough experiments have confirmed the selective retention of NO 2 by Zr-bptc at low concentrations under both dry and wet conditions. The immobilized NO 2 can be readily transformed into valuable nitro compounds relevant to construction, agrochemical, and pharmaceutical industries. In situ crystallographic and spectroscopic studies reveal strong binding interactions of NO 2 to the {Zr 6 (μ 3 -O) 4 (μ 3 -OH) 4 (COO) 12 } cluster node. This study paves a circular pathway to enable the integration of nitrogen-based air pollutants into the production of fine chemicals.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Structural and Dynamic Analysis of Sulphur Dioxide Adsorption in a Series of Zirconium-Based Metal–Organic Frameworks
We report reversible high capacity adsorption of SO 2 in robust Zr-based metal–organic framework (MOF) materials. Zr-bptc (H 4 bptc=biphenyl-3,3',5,5'-tetracarboxylic acid) shows a high SO 2 uptake of 6.2 mmol g -1 at 0.1 bar and 298 K, reflecting excellent capture capability and removal of SO 2 at low concentration (2500 ppm). Dynamic breakthrough experiments confirm that the introduction of amine, atomically-dispersed Cu II or heteroatomic sulphur sites into the pores enhance the capture of SO 2 at low concentrations. The captured SO 2 can be converted quantitatively to a pharmaceutical intermediate, aryl N-aminosulfonamide, thus converting waste to chemical values. In situ X-ray diffraction, infrared micro-spectroscopy and inelastic neutron scattering enable the visualisation of the binding domains of adsorbed SO 2 molecules and host–guest binding dynamics in these materials at the atomic level. Refinement of the pore environment plays a critical role in designing efficient sorbent materials.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Direct Observation of Ammonia Storage in UiO-66 Incorporating Cu(II) Binding Sites
The presence of active sites in metal–organic framework (MOF) materials can control and affect their performance significantly in adsorption and catalysis. However, revealing the interactions between the substrate and active sites in MOFs at atomic precision remains a challenging task. Here, we report the direct observation of binding of NH 3 in a series of UiO-66 materials containing atomically dispersed defects and open Cu(I) and Cu(II) sites. While all MOFs in this series exhibit similar surface areas (1111–1135 m 2 g –1 ), decoration of the -OH site in UiO-66-defect with Cu(II) results in a 43% enhancement of the isothermal uptake of NH 3 at 273 K and 1.0 bar from 11.8 in UiO-66-defect to 16.9 mmol g –1 in UiO-66-Cu II . A 100% enhancement of dynamic adsorption of NH 3 at a concentration level of 630 ppm from 2.07 mmol g –1 in UiO-66-defect to 4.15 mmol g –1 in UiO-66-Cu II at 298 K is observed. In situ neutron powder diffraction, inelastic neutron scattering, and electron paramagnetic resonance, solid-state nuclear magnetic resonance, and infrared spectroscopies, coupled with modeling reveal that the enhanced NH 3 uptake in UiO-66-Cu II originates from a {Cu(II)···NH 3 } interaction, with a reversible change in geometry at Cu(II) from near-linear to trigonal coordination. This work represents the first example of structural elucidation of NH 3 binding in MOFs containing open metal sites and will inform the design of new efficient MOF sorbents by targeted control of active sites for NH 3 capture and storage.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
High capacity ammonia adsorption in a robust metal–organic framework mediated by reversible host–guest interactions
To understand the exceptional adsorption of ammonia (NH 3 ) in MFM-300(Sc) (19.5 mmol g -1 at 273 K and 1 bar without hysteresis), we report a systematic investigation of the mechanism of adsorption by a combination of in situ neutron powder diffraction, inelastic neutron scattering, synchrotron infrared microspectroscopy, and solid-state 45 Sc NMR spectroscopy. These complementary techniques reveal the formation of reversible host–guest supramolecular interactions, which explains directly the observed excellent reversibility of this material over 90 adsorption–desorption cycles.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
A {Ni 12 }-Wheel-Based Metal-Organic Framework for Coordinative Binding of Sulphur Dioxide and Nitrogen Dioxide
Air pollution by SO 2 and NO 2 has caused significant risks on the environment and human health. Understanding the mechanism of active sites within capture materials is of fundamental importance to the development of new clean-up technologies. We report the crystallographic observation of reversible coordinative binding of SO 2 and NO 2 on open Ni II sites in a metal-organic framework (NKU-100) incorporating unprecedented {Ni 12 }-wheels; each wheel exhibits six open Ni II sites on desolvation. Immobilised gas molecules are further stabilised by cooperative host-guest interactions comprised of hydrogen bonds, π∙∙∙π interactions and dipole interactions. At 298 K and 1.0 bar, NKU-100 shows adsorption uptakes of 6.21 and 5.80 mmol g -1 for SO 2 and NO 2 , respectively. Dynamic breakthrough experiments have confirmed the selective retention of SO 2 and NO 2 at low concentrations under dry conditions. This work will inspire the future design of efficient sorbents for the capture of SO 2 and NO 2 .
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Pore Distortion in a Metal–Organic Framework for Regulated Separation of Propane and Propylene
The development of porous solids for adsorptive separation of propylene and propane remains an important and challenging line of research. State-of-the-art sorbent materials often suffer from the trade-off between adsorption capacity and selectivity. Here, we report the regulated separation of propylene and propane in a metal–organic framework via designed pore distortion. Here, the distorted pore structure of HIAM-301 successfully excludes propane and thus achieved simultaneously high selectivity (>150) and large capacity (~3.2 mmol/g) of propylene at 298 K and 1 bar. Dynamic breakthrough measurements validated the excellent separation of propane and propylene. In situ neutron powder diffraction and inelastic neutron scattering revealed the binding domains of adsorbed propylene molecules in HIAM-301 as well as host–guest interaction dynamics. This study presents a new benchmark for the adsorptive separation of propylene and propane.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Exceptional Packing Density of Ammonia in a Dual-Functionalized Metal–Organic Framework
We report the reversible adsorption of ammonia (NH 3 ) up to 9.9 mmol g -1 in a robust Al-based metal-organic framework, MFM-303(Al), which is functionalized with free carboxylic acid and hydroxyl groups. The unique pore environment decorated with these acidic sites results in an exceptional packing density of NH 3 at 293 K (0.801 g cm -3 ) comparable to that of solid NH 3 at 193 K (0.817 g cm-3 ). In situ synchrotron X-ray diffraction and inelastic neutron scattering reveal the critical role of free -COOH and -OH groups in immobilizing NH 3 molecules. Breakthrough experiments confirm the excellent performance of MFM-303(Al) for the capture of NH 3 at low concentrations under both dry and wet conditions.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Purification of Propylene and Ethylene by a Robust Metal–Organic Framework Mediated by Host–Guest Interactions
Industrial purification of propylene and ethylene requires cryogenic distillation and selective hydrogenation over palladium catalysts to remove propane, ethane and/or trace amounts of acetylene. Here, we report the excellent separation of equimolar mixtures of propylene/propane and ethylene/ethane, and of a 1/100 mixture of acetylene/ethylene by a highly robust microporous material, MFM-520, under dynamic conditions. In situ synchrotron single crystal X-ray diffraction, inelastic neutron scattering and analysis of adsorption thermodynamic parameters reveal that a series of synergistic host-guest interactions involving hydrogen bonding and π⋯π stacking interactions underpin the cooperative binding of alkenes within the pore. Notably, the optimal pore geometry of the material enables selective accommodation of acetylene. The practical potential of this porous material has been demonstrated by fabricating mixed-matrix membranes comprising MFM-520, Matrimid and PIM-1, and these exhibit not only a high permeability for propylene (≈1984 Barrer), but also a separation factor of 7.8 for an equimolar mixture of propylene/propane at 298 K.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
High Ammonia Adsorption in MFM-300 Materials: Dynamics and Charge Transfer in Host–Guest Binding
Ammonia (NH 3 ) is a promising energy resource owing to its high hydrogen density. However, its widespread application is restricted by the lack of efficient and corrosion-resistant storage materials. In this work, we report high NH 3 adsorption in a series of robust metal-organic framework (MOF) materials, MFM-300(M) (M = Fe, V, Cr, In). MFM-300(M) (M = Fe, V III , Cr) show fully reversible capacity for >20 cycles, reaching capacities of 16.1, 15.6, and 14.0 mmol g -1 , respectively, at 273 K and 1 bar. Under the same conditions, MFM-300(V IV ) exhibits the highest uptake among this series of MOFs of 17.3 mmol g -1 . In situ neutron powder diffraction, single-crystal X-ray diffraction, and electron paramagnetic resonance spectroscopy confirm that the redox-active V center enables host-guest charge transfer, with V IV being reduced to V III and NH 3 being oxidized to hydrazine (N 2 H 4 ). A combination of in situ inelastic neutron scattering and DFT modeling has revealed the binding dynamics of adsorbed NH 3 within these MOFs to afford a comprehensive insight into the application of MOF materials to the adsorption and conversion of NH 3 .
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Guest-Controlled Incommensurate Modulation in a Meta-Rigid Metal–Organic Framework Material
Structural transitions of host systems in response to guest binding dominate many chemical processes. We report an unprecedented type of structural flexibility within a meta-rigid material, MFM-520, which exhibits a reversible periodic-to-aperiodic structural transition resulting from a drastic distortion of a [ZnO 4 N] node controlled by the specific host–guest interactions. The aperiodic crystal structure of MFM-520 has no three-dimensional (3D) lattice periodicity but shows translational symmetry in higher-dimensional (3 + 2)D space. In this work, we have directly visualized the aperiodic state which is induced by incommensurate modulation of the periodic framework of MFM-520·H 2 O upon dehydration to give MFM-520. Filling MFM-520 with CO 2 and SO 2 reveals that, while CO 2 has a minimal structural influence, SO 2 can further modulate the structure incommensurately. MFM-520 shows exceptional selectivity for SO 2 under flue-gas desulfurization conditions, and the facile release of captured SO 2 from MFM-520 enabled the conversion to valuable sulfonamide products. MFM-520 can thus be used as a highly efficient capture and delivery system for SO 2 .
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Radiative Flux and Forcing Parameterization Error in Aerosol-Free Clear Skies
This article reports on the accuracy in aerosol- and cloud-free conditions of the radiation parameterizations used in climate models. Accuracy is assessed relative to observationally validated reference models for fluxes under present-day conditions and forcing (flux changes) from quadrupled concentrations of carbon dioxide. Agreement among reference models is typically within 1 W/m2, while parameterized calculations are roughly half as accurate in the longwave and even less accurate, and more variable, in the shortwave. Absorption of shortwave radiation is underestimated by most parameterizations in the present day and has relatively large errors in forcing. Error in present-day conditions is essentially unrelated to error in forcing calculations. Recent revisions to parameterizations have reduced error in most cases. A dependence on atmospheric conditions, including integrated water vapor, means that global estimates of parameterization error relevant for the radiative forcing of climate change will require much more ambitious calculations.
Climate↗
The Continual Intercomparison of Radiation Codes: Results from Phase I
The computer codes that calculate the energy budget of solar and thermal radiation in Global Climate Models (GCMs), our most advanced tools for predicting climate change, have to be computationally efficient in order to not impose undue computational burden to climate simulations. By using approximations to gain execution speed, these codes sacrifice accuracy compared to more accurate, but also much slower, alternatives. International efforts to evaluate the approximate schemes have taken place in the past, but they have suffered from the drawback that the accurate standards were not validated themselves for performance. The manuscript summarizes the main results of the first phase of an effort called "Continual Intercomparison of Radiation Codes" (CIRC) where the cases chosen to evaluate the approximate models are based on observations and where we have ensured that the accurate models perform well when compared to solar and thermal radiation measurements. The effort is endorsed by international organizations such as the GEWEX Radiation Panel and the International Radiation Commission and has a dedicated website (i.e., http://circ.gsfc.nasa.gov) where interested scientists can freely download data and obtain more information about the effort's modus operandi and objectives. In a paper published in the March 2010 issue of the Bulletin of the American Meteorological Society only a brief overview of CIRC was provided with some sample results. In this paper the analysis of submissions of 11 solar and 13 thermal infrared codes relative to accurate reference calculations obtained by so-called "line-by-line" radiation codes is much more detailed. We demonstrate that, while performance of the approximate codes continues to improve, significant issues still remain to be addressed for satisfactory performance within GCMs. We hope that by identifying and quantifying shortcomings, the paper will help establish performance standards to objectively assess radiation code quality, and will guide the development of future phases of CIRC
Oreopoulos, Lazaros↗