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Heard CJ, Grajciar L, Erlebach A. Migration of zeolite-encapsulated subnanometre platinum clusters via reactive neural network potentials. NANOSCALE 2024; 16:8108-8118. [PMID: 38567421 DOI: 10.1039/d4nr00017j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
The migration of atoms and small clusters is an important process in sub-nanometre scale heterogeneous catalysis, affecting activity, accessibility and deactivation through sintering. Control of migration can be partially achieved via encapsulation of sub-nanometre metal particles into porous media such as zeolites. However, a general understanding of the migration mechanisms and their sensitivity to particle size and framework environment is lacking. Here, we extend the time-scale and sampling of atomistic simulations of platinum cluster diffusion in siliceous zeolite frameworks, by introducing a reactive neural network potential of density functional quality. We observe that Pt atoms migrate in a qualitatively different manner from clusters, occupying the dense region of the framework and avoiding the free pore space. We also find that for cage-like zeolite CHA there exists a maximum in self diffusivity for the Pt dimer beyond which, confinement effects hinder intercage migration. By extending the quality of sampling, NNP-based methods allow for the discovery of novel dynamical processes at the atomistic scale, bringing modelling closer to operando experimental characterization of catalytic materials.
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Affiliation(s)
- Christopher J Heard
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Praha 2, 12843, Czech Republic.
| | - Lukáš Grajciar
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Praha 2, 12843, Czech Republic.
| | - Andreas Erlebach
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Praha 2, 12843, Czech Republic.
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2
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Li Y, Chen D, Xu X, Wang X, Kang R, Fu M, Guo Y, Chen P, Li Y, Ye D. Cold-Start NO x Mitigation by Passive Adsorption Using Pd-Exchanged Zeolites: From Material Design to Mechanism Understanding and System Integration. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:3467-3485. [PMID: 36802541 DOI: 10.1021/acs.est.2c06207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
It remains a major challenge to abate efficiently the harmful nitrogen oxides (NOx) in low-temperature diesel exhausts emitted during the cold-start period of engine operation. Passive NOx adsorbers (PNA), which could temporarily capture NOx at low temperatures (below 200 °C) and release the stored NOx at higher temperatures (normally 250-450 °C) to downstream selective catalytic reduction unit for complete abatement, hold promise to mitigate cold-start NOx emissions. In this review, recent advances in material design, mechanism understanding, and system integration are summarized for PNA based on palladium-exchanged zeolites. First, we discuss the choices of parent zeolite, Pd precursor, and synthetic method for the synthesis of Pd-zeolites with atomic Pd dispersions, and review the effect of hydrothermal aging on the properties and PNA performance of Pd-zeolites. Then, we show how different experimental and theoretical methodologies can be integrated to gain mechanistic insights into the nature of Pd active sites, the NOx storage/release chemistry, as well as the interactions between Pd and typical components/poisons in engine exhausts. This review also gathers several novel designs of PNA integration into modern exhaust after-treatment systems for practical application. At the end, we discuss the major challenges, as well as important implications, for the further development and real application of Pd-zeolite-based PNA in cold-start NOx mitigation.
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Affiliation(s)
- Ying Li
- National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, 510006 Guangzhou, China
| | - Dongdong Chen
- National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, 510006 Guangzhou, China
| | - Xin Xu
- National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, 510006 Guangzhou, China
| | - Xinyu Wang
- National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, 510006 Guangzhou, China
| | - Running Kang
- Department of Chemical and Metallurgical Engineering, School of Chemical Engineering, Aalto University, 02150 Espoo, Finland
| | - Mingli Fu
- National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, 510006 Guangzhou, China
| | - Yanbing Guo
- Institute of Environmental and Applied Chemistry, College of Chemistry, Central China Normal University, 430079 Wuhan, China
| | - Peirong Chen
- National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, 510006 Guangzhou, China
| | - Yongdan Li
- Department of Chemical and Metallurgical Engineering, School of Chemical Engineering, Aalto University, 02150 Espoo, Finland
| | - Daiqi Ye
- National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, 510006 Guangzhou, China
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3
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Aljama HA, Head-Gordon M, Bell AT. Assessing the stability of Pd-exchanged sites in zeolites with the aid of a high throughput quantum chemistry workflow. Nat Commun 2022; 13:2910. [PMID: 35614062 PMCID: PMC9133006 DOI: 10.1038/s41467-022-29505-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 02/22/2022] [Indexed: 01/03/2023] Open
Abstract
Cation exchanged-zeolites are functional materials with a wide range of applications from catalysis to sorbents. They present a challenge for computational studies using density functional theory due to the numerous possible active sites. From Al configuration, to placement of extra framework cation(s), to potentially different oxidation states of the cation, accounting for all these possibilities is not trivial. To make the number of calculations more tractable, most studies focus on a few active sites. We attempt to go beyond these limitations by implementing a workflow for a high throughput screening, designed to systematize the problem and exhaustively search for feasible active sites. We use Pd-exchanged CHA and BEA to illustrate the approach. After conducting thousands of explicit DFT calculations, we identify the sites most favorable for the Pd cation and discuss the results in detail. The high throughput screening identifies many energetically favorable sites that are non-trivial. Lastly, we employ these results to examine NO adsorption in Pd-exchanged CHA, which is a promising passive NOx adsorbent (PNA) during the cold start of automobiles. The results shed light on critical active sites for NOx capture that were not previously studied.
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Affiliation(s)
- Hassan A Aljama
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, USA
| | - Martin Head-Gordon
- Department of Chemistry, University of California, Berkeley, CA, USA.
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Alexis T Bell
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, USA.
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4
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Kaushik M, Shrivastav G, Khan TS, Haider MA, Bhatia D. The Operating Cycle of NO Adsorption and Desorption in Pd-Chabazite for Passive NO x Adsorbers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:13799-13809. [PMID: 34766776 DOI: 10.1021/acs.langmuir.1c01383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Pd-doped chabazite (Pd/CHA) offers unique opportunities to adsorb and desorb NOx in the target temperature range for application as a passive NOx adsorber (PNA). The ability of Pd/CHA to trap NOx emissions at low temperatures (<200 °C) is facilitated by the binding of NOx species at various Pd sites available in the CHA framework. Density functional theory (DFT) simulations are performed to understand Pd speciation in CHA and the interaction of NO with Pd/CHA to explain the mechanisms of NO adsorption, oxidation, and desorption processes. The calculations are used to elucidate the important role of Pd1+ cationic species, anchored at 6MR-3NN, in providing a strong (Eb = -272 kJ/mol) NO adsorption site in Pd/CHA. For NO release, the redox transformation of Pd species comes into play and Pd1+ species are suggested to transform into cationic Pd2+, [PdOH]+, or [Pd-O-Pd]2+ species, all of which show significantly reduced NO binding (-116, -153, and -117 kJ/mol, respectively) as compared to Pd1+. This enables NO desorption at the operating temperature of a downstream catalyst for subsequent catalytic reduction.
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Affiliation(s)
- Marvi Kaushik
- Department of Chemical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Gourav Shrivastav
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Tuhin S Khan
- Light Stock Processing Division, CSIR─Indian Institute of Petroleum, Mohkampur, Dehradun 248005, India
| | - M Ali Haider
- Department of Chemical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Divesh Bhatia
- Department of Chemical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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5
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Pace R, Lardinois TM, Ji Y, Gounder R, Heintz O, Crocker M. Effects of Treatment Conditions on Pd Speciation in CHA and Beta Zeolites for Passive NO x Adsorption. ACS OMEGA 2021; 6:29471-29482. [PMID: 34778619 PMCID: PMC8581994 DOI: 10.1021/acsomega.1c03440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 10/12/2021] [Indexed: 05/14/2023]
Abstract
The structure and evolution of Pd species in Pd-exchanged zeolite materials intended for use as passive NO x adsorbers were examined under various pretreatment conditions. Using in situ CO-diffuse reflectance infrared spectroscopy, Pd structures were characterized after 500 °C pretreatments in inert (Ar), water (1-2% H2O in Ar), oxidizing (air), and reducing (H2, CO) atmospheres. Two zeolites of similar Si/Al ratios but different framework topologies (Beta, CHA) were found to show different distributions of Pd species, depending on the reducing agent used. Reduction in H2 (500 °C; 10% H2 in Ar) followed by re-oxidation (500 °C; air) led to higher amounts of single-site Pd ions on Pd-CHA than Pd-Beta, whereas high-temperature reduction in CO (500 °C; 1000 ppm CO in Ar) followed by re-oxidation (500 °C; air) led to significant loss of ionic Pd on both Pd-CHA and Pd-Beta, albeit H2 temperature-programmed reduction and XPS experiments suggest that this phenomena may be limited to surface Pd. High-temperature treatments with water (500 °C; 1-2% H2O in Ar) are shown to form either Pd metal or PdO particles, with Pd-Beta being more susceptible to these effects than Pd-CHA. This work suggests that the effects of CO are especially problematic with respect to the durability of these materials in passive NO x adsorption applications, especially in the case of Beta zeolite.
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Affiliation(s)
- Robert
B. Pace
- Center
for Applied Energy Research, University
of Kentucky, 2540 Research Park Drive, Lexington, Kentucky 0511, United States
- Department
of Chemistry, University of Kentucky, 161 Jacobs Science Building, Lexington, Kentucky 40506, United States
| | - Trevor M. Lardinois
- Charles
D. Davidson School of Chemical Engineering, Purdue University, 701 W Stadium Ave. #3000, West Lafayette, Indiana 47907, United States
| | - Yaying Ji
- Center
for Applied Energy Research, University
of Kentucky, 2540 Research Park Drive, Lexington, Kentucky 0511, United States
| | - Rajamani Gounder
- Charles
D. Davidson School of Chemical Engineering, Purdue University, 701 W Stadium Ave. #3000, West Lafayette, Indiana 47907, United States
| | - Olivier Heintz
- Laboratoire
Interdisciplinaire Carnot de Bourgogne (LICB), UMR CNRS 6303, Université
de BourgogneFranche-Comté, 9 Avenue Alain Savary, 21078 Dijon Cedex, France
| | - Mark Crocker
- Center
for Applied Energy Research, University
of Kentucky, 2540 Research Park Drive, Lexington, Kentucky 0511, United States
- Department
of Chemistry, University of Kentucky, 161 Jacobs Science Building, Lexington, Kentucky 40506, United States
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6
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Yasumura S, Ueda T, Ide H, Otsubo K, Liu C, Tsunoji N, Toyao T, Maeno Z, Shimizu KI. Local structure and NO adsorption/desorption property of Pd 2+ cations at different paired Al sites in CHA zeolite. Phys Chem Chem Phys 2021; 23:22273-22282. [PMID: 34644369 DOI: 10.1039/d1cp02668b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Recently, Pd-exchanged CHA zeolites (Pd-CHA) have attracted attention as promising passive NOx adsorbers (PNAs) for reducing NOx emissions during the cold start period of a vehicle engine. In this work, the relationship between the local structures and the NO adsorption/desorption properties of the Pd cations in CHA zeolites was investigated. Pd cation formation and NO adsorption were theoretically explored by density functional theory (DFT) calculations for different paired Al sites in six-/eight-membered rings (6MR/8MR). Furthermore, we prepared a series of Pd-CHAs with different Pd loadings (0.5-5.4 wt%) and evaluated their NO adsorption/desorption properties by in situ infrared (IR) spectroscopy and temperature-programmed desorption (TPD) measurements. The increase in the Pd loading resulted in a shift in the NO desorption temperature toward a higher temperature regime. This phenomenon was ascribed to the increase in the proportion of less stable Pd cations, resulting in improved NO adsorption. Furthermore, the effect of Al distribution on the NO adsorption property of Pd-CHA was examined using CHA zeolites containing different proportions of paired Al sites in 6MR while maintaining similar Si/Al ratios (Si/Al = 12.0-16.5). The present study, based on a combination of theoretical and experimental techniques, shows that the NO adsorption/desorption properties over Pd-CHA can be tuned by controlling the Pd loading amount and the type of paired Al sites.
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Affiliation(s)
- Shunsaku Yasumura
- Institute for Catalysis, Hokkaido University, N-21, W-10, Sapporo 001-0021, Japan.
| | - Taihei Ueda
- Institute for Catalysis, Hokkaido University, N-21, W-10, Sapporo 001-0021, Japan.
| | - Hajime Ide
- Institute for Catalysis, Hokkaido University, N-21, W-10, Sapporo 001-0021, Japan.
| | - Katsumasa Otsubo
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan
| | - Chong Liu
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
| | - Nao Tsunoji
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan
| | - Takashi Toyao
- Institute for Catalysis, Hokkaido University, N-21, W-10, Sapporo 001-0021, Japan. .,Elements Strategy Initiative for Catalysts and Batteries, Kyoto University, Katsura, Kyoto 615-8520, Japan
| | - Zen Maeno
- Institute for Catalysis, Hokkaido University, N-21, W-10, Sapporo 001-0021, Japan.
| | - Ken-Ichi Shimizu
- Institute for Catalysis, Hokkaido University, N-21, W-10, Sapporo 001-0021, Japan. .,Elements Strategy Initiative for Catalysts and Batteries, Kyoto University, Katsura, Kyoto 615-8520, Japan
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7
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Serna P, Rodríguez-Fernández A, Yacob S, Kliewer C, Moliner M, Corma A. Single-Site vs. Cluster Catalysis in High Temperature Oxidations. Angew Chem Int Ed Engl 2021; 60:15954-15962. [PMID: 33881798 DOI: 10.1002/anie.202102339] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 04/07/2021] [Indexed: 12/28/2022]
Abstract
The behavior of single Pt atoms and small Pt clusters was investigated for high-temperature oxidations. The high stability of these molecular sites in CHA is a key to intrinsic structure-performance descriptions of elemental steps such as O2 dissociation, and subsequent oxidation catalysis. Subtle changes in the atomic structure of Pt are responsible for drastic changes in performance driven by specific gas/metal/support interactions. Whereas single Pt atoms and Pt clusters (> ca. 1 nm) are unable to activate, scramble, and desorb two O2 molecules at moderate T (200 °C), clusters <1 nm do so catalytically, but undergo oxidative fragmentation. Oxidation of alkanes at high T is attributed to stable single Pt atoms, and the C-H cleavage is inferred to be rate-determining and less sensitive to changes in metal nuclearity compared to its effect on O2 scrambling. In contrast, when combustion involves CO, catalysis is dominated by metal clusters, not single Pt atoms.
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Affiliation(s)
- Pedro Serna
- ExxonMobil Research and Engineering Co., Corporate Strategic Research, Annandale, NJ, 08801, USA
| | - Aida Rodríguez-Fernández
- Instituto de Tecnología Química, Universitat Politècnica de València-Consejo Superior de Investigaciones Cientificas (UPV-CSIC), Av. de los Naranjos, s/n, 46022, Valencia, Spain
| | - Sara Yacob
- ExxonMobil Research and Engineering Co., Corporate Strategic Research, Annandale, NJ, 08801, USA
| | - Christine Kliewer
- ExxonMobil Research and Engineering Co., Corporate Strategic Research, Annandale, NJ, 08801, USA
| | - Manuel Moliner
- Instituto de Tecnología Química, Universitat Politècnica de València-Consejo Superior de Investigaciones Cientificas (UPV-CSIC), Av. de los Naranjos, s/n, 46022, Valencia, Spain
| | - Avelino Corma
- Instituto de Tecnología Química, Universitat Politècnica de València-Consejo Superior de Investigaciones Cientificas (UPV-CSIC), Av. de los Naranjos, s/n, 46022, Valencia, Spain
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8
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Serna P, Rodríguez‐Fernández A, Yacob S, Kliewer C, Moliner M, Corma A. Single‐Site vs. Cluster Catalysis in High Temperature Oxidations. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202102339] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Pedro Serna
- ExxonMobil Research and Engineering Co. Corporate Strategic Research Annandale NJ 08801 USA
| | - Aida Rodríguez‐Fernández
- Instituto de Tecnología Química, Universitat Politècnica de València—Consejo Superior de Investigaciones Cientificas (UPV-CSIC) Av. de los Naranjos, s/n 46022 Valencia Spain
| | - Sara Yacob
- ExxonMobil Research and Engineering Co. Corporate Strategic Research Annandale NJ 08801 USA
| | - Christine Kliewer
- ExxonMobil Research and Engineering Co. Corporate Strategic Research Annandale NJ 08801 USA
| | - Manuel Moliner
- Instituto de Tecnología Química, Universitat Politècnica de València—Consejo Superior de Investigaciones Cientificas (UPV-CSIC) Av. de los Naranjos, s/n 46022 Valencia Spain
| | - Avelino Corma
- Instituto de Tecnología Química, Universitat Politècnica de València—Consejo Superior de Investigaciones Cientificas (UPV-CSIC) Av. de los Naranjos, s/n 46022 Valencia Spain
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Zhao H, Hill AJ, Ma L, Bhat A, Jing G, Schwank JW. Progress and future challenges in passive NO adsorption over Pd/zeolite catalysts. Catal Sci Technol 2021. [DOI: 10.1039/d1cy01084k] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Proposed NO adsorption cycles over Pd/zeolite materials.
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Affiliation(s)
- Huawang Zhao
- Department of Environmental Science & Engineering, College of Chemical Engineering, Huaqiao University, Xiamen, Fujian 361021, China
| | - Alexander J. Hill
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Lei Ma
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Adarsh Bhat
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Guohua Jing
- Department of Environmental Science & Engineering, College of Chemical Engineering, Huaqiao University, Xiamen, Fujian 361021, China
| | - Johannes W. Schwank
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
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