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Warmuth L, Steurer M, Schild D, Zimina A, Grunwaldt JD, Pitter S. Reversible and Irreversible Structural Changes in Cu/ZnO/ZrO 2 Catalysts during Methanol Synthesis. ACS APPLIED MATERIALS & INTERFACES 2024; 16:8813-8821. [PMID: 38335022 DOI: 10.1021/acsami.3c17383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
The structure and chemical state of heterogeneous catalysts are closely related to their operational stability. Knowing these relationships as precisely as possible is thus essential for further catalyst development. This work focuses on the deactivation of a Cu/ZnO/ZrO2-type catalyst for methanol synthesis. Experiments were performed in a parallel setup, with which time-dependent changes in the catalyst material can be observed. Elucidation of potential deactivation pathways is described for catalyst aging at different times on stream (0, 50, 935 h). Data from X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, N2 physisorption, and transmission electron microscopy measurements reveal that sintering of Cu0 domains and restructuring within ZnO domains mainly contribute to deactivation. Subsequent reactivation by reduction (in H2/N2) reverts the observed structural changes only to a limited extent. Moreover, this work highlights the participation of ZrO2 as a promoter and reveals redispersion of zirconia after initial reduction.
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Affiliation(s)
- Lucas Warmuth
- Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany
| | - Matthias Steurer
- Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany
| | - Dieter Schild
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany
| | - Anna Zimina
- Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany
- Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
| | - Jan-Dierk Grunwaldt
- Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany
- Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
| | - Stephan Pitter
- Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany
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Kubas D, Beck JM, Kasisari E, Schätzler T, Becherer A, Fischer A, Krossing I. From CO 2 to DME: Enhancement through Heteropoly Acids from a Catalyst Screening and Stability Study. ACS OMEGA 2023; 8:15203-15216. [PMID: 37151500 PMCID: PMC10157840 DOI: 10.1021/acsomega.3c00149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 03/27/2023] [Indexed: 05/09/2023]
Abstract
The direct synthesis of dimethyl ether (DME) via CO2 hydrogenation in a single step was studied using an improved class of bifunctional catalysts in a fixed bed reactor (T R: 210-270 °C; 40 bar; gas hourly space velocity (GHSV) 19,800 NL kgcat -1 h-1; ratio CO2/H2/N2 3:9:2). The competitive bifunctional catalysts tested in here consist of a surface-basic copper/zinc oxide/zirconia (CZZ) methanol-producing part and a variable surface-acidic methanol dehydration part and were tested in overall 45 combinations. As dehydration catalysts, zeolites (ferrierite and β-zeolite), alumina, or zirconia were tested alone as well as with a coating of Keggin-type heteropoly acids (HPAs), i.e., silicotungstic or phosphotungstic acid. Two different mixing methods to generate bifunctional catalysts were tested: (i) a single-grain method with intensive intra-particular contact between CZZ and the dehydration catalyst generated by mixing in an agate mortar and (ii) a dual-grain approach relying on physical mixing with low contact. The influence of the catalyst mixing method and HPA loading on catalyst activity and stability was investigated. From these results, a selection of best-performing bifunctional catalysts was investigated in extended measurements (time on stream: 160 h/7 days, T R: 250 and 270 °C; 40 bar; GHSV 19,800 NL kgcat -1 h-1; ratio CO2/H2/N2 3:9:2). Silicotungstic acid-coated bifunctional catalysts showed the highest resilience toward deactivation caused by single-grain preparation and during catalysis. Overall, HPA-coated catalysts showed higher activity and resilience toward deactivation than uncoated counterparts. Dual-grain preparation showed superior performance over single grain. Furthermore, silicotungstic acid coatings with 1 KU nm-2 (Keggin unit per surface area of carrier) on Al2O3 and ZrO2 as carrier materials showed competitive high activity and stability in extended 7-day measurements compared to pure CZZ. Therefore, HPA coating is found to be a well-suited addition to the CO2-to-DME catalyst toolbox.
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Affiliation(s)
- Dustin Kubas
- Institut
für Anorganische und Analytische Chemie, Universität
Freiburg, Albertstr.
21, 79104 Freiburg, Germany
- Freiburger
Materialforschungszentrum (FMF), Universität
Freiburg, Stefan-Meier-Straße
21, 79104 Freiburg, Germany
| | - Jennifer Maria Beck
- Institut
für Anorganische und Analytische Chemie, Universität
Freiburg, Albertstr.
21, 79104 Freiburg, Germany
- Freiburger
Materialforschungszentrum (FMF), Universität
Freiburg, Stefan-Meier-Straße
21, 79104 Freiburg, Germany
| | - Erdogan Kasisari
- Institut
für Anorganische und Analytische Chemie, Universität
Freiburg, Albertstr.
21, 79104 Freiburg, Germany
| | - Timo Schätzler
- Institut
für Anorganische und Analytische Chemie, Universität
Freiburg, Albertstr.
21, 79104 Freiburg, Germany
| | - Anita Becherer
- Institut
für Anorganische und Analytische Chemie, Universität
Freiburg, Albertstr.
21, 79104 Freiburg, Germany
| | - Anna Fischer
- Institut
für Anorganische und Analytische Chemie, Universität
Freiburg, Albertstr.
21, 79104 Freiburg, Germany
- Freiburger
Materialforschungszentrum (FMF), Universität
Freiburg, Stefan-Meier-Straße
21, 79104 Freiburg, Germany
| | - Ingo Krossing
- Institut
für Anorganische und Analytische Chemie, Universität
Freiburg, Albertstr.
21, 79104 Freiburg, Germany
- Freiburger
Materialforschungszentrum (FMF), Universität
Freiburg, Stefan-Meier-Straße
21, 79104 Freiburg, Germany
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Weldeslase MG, Benti NE, Desta MA, Mekonnen YS. Maximizing biodiesel production from waste cooking oil with lime-based zinc-doped CaO using response surface methodology. Sci Rep 2023; 13:4430. [PMID: 36932169 PMCID: PMC10023746 DOI: 10.1038/s41598-023-30961-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 03/03/2023] [Indexed: 03/19/2023] Open
Abstract
Biodiesel is one of the alternative fuels, commonly produced chemically from oil and methanol using a catalyst. This study aims to maximize biodiesel production from cheap and readily available sources of waste cooking oil (WCO) and lime-based Zinc-doped calcium oxide (Zn-CaO) catalyst prepared with a wet impregnation process. The Zn-CaO nanocatalyst was produced by adding 5% Zn into the calcinated limestone. The morphology, crystal size, and vibrational energies of CaO and Zn-CaO nanocatalysts were determined using SEM, XRD, and FT-IR spectroscopy techniques, respectively. The response surface methodology (RSM), which is based on the box-Behnken design, was used to optimize the key variables of the transesterification reaction. Results showed that when Zn was doped to lime-based CaO, the average crystalline size reduced from 21.14 to 12.51 nm, consequently, structural irregularity and surface area increased. The experimental parameters of methanol to oil molar ratio (14:1), catalyst loading (5% wt.), temperature (57.5 °C), and reaction time (120 min) led to the highest biodiesel conversion of 96.5%. The fuel characteristics of the generated biodiesel fulfilled the American (ASTM D6571) fuel standards. The study suggests the potential use of WCO and lime-based catalyst as efficient and low-cost raw materials for large-scale biodiesel production intended for versatile applications.
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Affiliation(s)
- Mebrhit Gebreyohanes Weldeslase
- Center for Environmental Science, College of Natural and Computational Sciences, Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia
| | - Natei Ermias Benti
- Computational Data Science Program, College of Natural and Computational Sciences, Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia
| | - Mekonnen Abebayehu Desta
- Department of Chemistry, College of Natural and Computational Sciences, Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia
| | - Yedilfana Setarge Mekonnen
- Center for Environmental Science, College of Natural and Computational Sciences, Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia.
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