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Recent progress of Pd/zeolite as passive NOx adsorber: Adsorption chemistry, structure-performance relationships, challenges and prospects. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2021.07.066] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Friberg I, Clark AH, Ho PH, Sadokhina N, Smales GJ, Woo J, Auvray X, Ferri D, Nachtegaal M, Kröcher O, Olsson L. Structure and performance of zeolite supported Pd for complete methane oxidation. Catal Today 2021. [DOI: 10.1016/j.cattod.2020.11.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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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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Effects of CO and H2O Co-Feed on the Adsorption and Oxidation Properties of a Pd/BEA Hydrocarbon Trap. Catalysts 2021. [DOI: 10.3390/catal11030348] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Hydrocarbon traps for exhaust emissions control adsorb hydrocarbons in low temperature exhaust and release them as the exhaust warms up. In this work, a Pd/BEA hydrocarbon trap was tested under lean exhaust conditions using ethylene and dodecane as model hydrocarbons. Ethylene uptake was partially inhibited by CO and H2O when fed separately. When both were added, the loss in ethylene uptake was 90% relative to the condition with no H2O or CO. Dodecane uptake was unchanged under all conditions tested. During a temperature ramp, ethylene desorbed and was combusted to CO2 and H2O over active Pd centers. Further, oxidation light-off of dodecane generated an exotherm which caused rapid desorption of the remaining hydrocarbon species from the zeolite. For both hydrocarbons, CO co-feed led to a decreased oxidation light-off temperature, and therefore lower desorption temperature. By pretreating the catalyst in CO and H2O at 80 °C, and even after removing CO from the feed, the enhanced oxidation light-off behavior was observed. DRIFTS characterization shows that some form of oxidized Pd was reducible to Pd0 by CO at 80 °C only in the presence of H2O. Further, this reduction appears reversible by high temperature oxygen treatment. We speculate that this reduced Pd phase serves as the active site for low temperature hydrocarbon oxidation.
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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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Deactivation of Pd/Zeolites passive NOx adsorber induced by NO and H2O: Comparative study of Pd/ZSM-5 and Pd/SSZ-13. Catal Today 2021. [DOI: 10.1016/j.cattod.2020.01.039] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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7
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Recent advances in catalytic automotive emission control: Passive
NO
storage at low temperatures. J CHIN CHEM SOC-TAIP 2020. [DOI: 10.1002/jccs.202000203] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
Important advances have been achieved over the past years in agriculture, industrial technology, energy, and health, which have contributed to human well-being [...]
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