Статті в журналах: "Catalyst aging"

1

Schütz, Jochen, Heike Störmer, Patrick Lott, and Olaf Deutschmann. "Effects of Hydrothermal Aging on CO and NO Oxidation Activity over Monometallic and Bimetallic Pt-Pd Catalysts." Catalysts 11, no. 3 (February 25, 2021): 300. http://dx.doi.org/10.3390/catal11030300.

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By combining scanning transmission electron microscopy, CO chemisorption, and energy dispersive X-ray spectroscopy with CO and NO oxidation light-off measurements we investigated deactivation phenomena of Pt/Al2O3, Pd/Al2O3, and Pt-Pd/Al2O3 model diesel oxidation catalysts during stepwise hydrothermal aging. Aging induces significant particle sintering that results in a decline of the catalytic activity for all catalyst formulations. While the initial aging step caused the most pronounced deactivation and sintering due to Ostwald ripening, the deactivation rates decline during further aging and the catalyst stabilizes at a low level of activity. Most importantly, we observed pronounced morphological changes for the bimetallic catalyst sample: hydrothermal aging at 750 °C causes a stepwise transformation of the Pt-Pd alloy via core-shell structures into inhomogeneous agglomerates of palladium and platinum. Our study shines a light on the aging behavior of noble metal catalysts under industrially relevant conditions and particularly underscores the highly complex transformation of bimetallic Pt-Pd diesel oxidation catalysts during hydrothermal treatment.

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2

Wang, Tae Joong, and In Hyuk Im. "Experimental and kinetic analysis of hydrothermal aging effects on ammonia adsorption capacity over a commercial Cu-zeolite selective catalytic reduction catalyst." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233, no. 12 (November 28, 2018): 3030–42. http://dx.doi.org/10.1177/0954407018814950.

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Ammonia/urea selective catalytic reduction is an efficient technology to control NOx emission from diesel engines. One of its critical challenges is the performance degradation of selective catalytic reduction catalysts due to the hydrothermal aging experienced in real-world operations during the lifetime. In this study, hydrothermal aging effects on the reduction of ammonia adsorption capacity over a commercial Cu-zeolite selective catalytic reduction catalyst were investigated under actual engine exhaust conditions. Ammonia adsorption site densities of the selective catalytic reduction catalysts aged at two different temperatures of 750°C and 850°C for 25 h with 10% H2O were experimentally measured and compared to that of fresh catalyst on a dynamometer test bench with a heavy-duty diesel engine. The test results revealed that hydrothermal aging significantly decreased the ammonia adsorption capacity of the current commercial Cu-zeolite selective catalytic reduction catalyst. Hydrothermal treatment at 750°C reduced the ammonia adsorption site to 62.5% level of that of fresh catalyst, while hydrothermal treatment at 850°C lowered the adsorption site to 37.0% level of that of fresh catalyst. Also, in this study, numerical simulation and kinetic analysis were carried out to quantify the impact of hydrothermal aging on the reduction of ammonia adsorption capacity by introducing an aging coefficient. The kinetic parameter calibrations based on actual diesel engine tests with a commercial monolith Cu-zeolite selective catalytic reduction catalyst provided a highly realistic kinetic parameter set of ammonia adsorption/desorption and enabled a mathematical description of hydrothermal aging effect.

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3

Kiss, Ernő, and Goran Boskovic. "Impeded solid state reactions and transformations in ceramic catalysts supports and catalysts." Processing and Application of Ceramics 6, no. 4 (2012): 173–82. http://dx.doi.org/10.2298/pac1204173k.

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Impeded chemical reactions and impeded polymorphous transformation in materials are discussed, as desired effects, for stabilization of ceramic catalyst supports and ceramic based catalysts. This paper gives a short overview about the possibilities of slowing down the aging processes in ceramic catalyst supports and catalysts. Special attention is given to alumina and titania based catalysts.

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4

Zhang, Wei Jun, Jin Hu, Hong Luo, Li Shen, Hua Tan, and Lin Su. "Relation between Cell Density and PM Content Investgation of Three-Way Catalyst." Advanced Materials Research 624 (December 2012): 291–94. http://dx.doi.org/10.4028/www.scientific.net/amr.624.291.

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In this paper, Pd/Rh series catalyst substrate samples were prepared at the different cell density, with different volume. The fresh catalyst aging treatment. And Catalysts test by light-off factor (LOF). The results tested demonstrated that, it can achieve equal performance levels with the cell density is 600cpsi that the catalyst sample of the cell density is 400cpsi with the precious metal content for the 1.2g/L. This is more efficient for low content of noble metal catalysts. This work is still importantly to promoted catalyst stability, that the catalyst structure is optimized. And it can be used as the interaction between cell density and noble metal content of catalysts.

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5

Morosanu, Eduard Alexandru, Fabio Salomone, Raffaele Pirone, and Samir Bensaid. "Insights on a Methanation Catalyst Aging Process: Aging Characterization and Kinetic Study." Catalysts 10, no. 3 (March 2, 2020): 283. http://dx.doi.org/10.3390/catal10030283.

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Power to gas systems is one of the most interesting long-term energy storage solutions. As a result of the high exothermicity of the CO2 methanation reaction, the catalyst in the methanation subsystem is subjected to thermal stress. Therefore, the performance of a commercial Ni/Al2O3 catalyst was investigated over a series of 100 hour-long tests and in-process relevant conditions, i.e. 5 bar from 270 to 500 °C. Different characterization techniques were employed to determine the mechanism of the observed performance loss (N2 physisorption, XRD, TPO). The TPO analysis excluded carbon deposition as a possible cause of catalyst aging. The BET analysis evidenced a severe reduction in the total surface area for the catalyst samples tested at higher temperatures. Furthermore, a direct correlation was found between the catalyst activity decline and the drop of the catalyst specific surface. In order to correctly design a reliable methanation reactor, it is essential to have a kinetic model that includes also the aging kinetics. For this purpose, the second set of experiments was carried out, in order to determine the intrinsic kinetics of the catalyst. The kinetic parameters were identified by using nonlinear regression analysis. Finally, a power-law aging model was proposed to consider the performance loss in time.

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6

Song, Chaoming, Lihong Zhang, Zhenguo Li, Yiren Lu, and Kaixiang Li. "Co-Exchange of Mn: A Simple Method to Improve Both the Hydrothermal Stability and Activity of Cu–SSZ-13 NH3–SCR Catalysts." Catalysts 9, no. 5 (May 17, 2019): 455. http://dx.doi.org/10.3390/catal9050455.

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A series of Cu–Mn–SSZ-13 catalysts were obtained by co-exchange of Mn and Cu into SSZ-13 together (ion exchange under a mixed solution of Cu(NO3)2 and Mn(NO3)2) and compared with Cu–SSZ-13 catalysts on the selective catalytic reduction (SCR) of nitric oxide (NO) by ammonia. The effects of total ion exchange degree and the effect of Mn species on the structure and performance of catalysts before and after hydrothermal aging were studied. All fresh and aged catalysts were characterized with several methods including temperature-programmed desorption with NH3 (NH3-TPD), X-ray diffraction (XRD), 27Al and 29Si solid-state nuclear magnetic resonance (NMR), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and low-temperature N2 adsorption–desorption techniques. The results showed that the increase of the total ion exchange degree can reduce the content of residual Brønsted acid sites of catalysts, thus relieved the dealumination and the decrease of crystallinity of the catalyst during hydrothermal aging. The moderate addition of a Mn component in Cu–Mn–SSZ-13 catalysts significantly increased the activity of NO conversion at low temperature range. The selected Cu(0.2)Mn(0.1)–SSZ-13 catalyst achieved a high NO conversion of >90% in the wide and low temperature range of 175–525 °C and also exhibited good N2 selectivity and excellent hydrothermal stability, which was related to the inhibition of the Mn component on the aggregation of Cu species and the pore destruction of the catalyst during hydrothermal aging.

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7

Kawanami, Yasuhiro, and Ryo Yanagita. "Practical Enantioselective Reduction of Ketones Using Oxazaborolidine Catalysts Generated In Situ from Chiral Lactam Alcohols." Molecules 23, no. 10 (September 20, 2018): 2408. http://dx.doi.org/10.3390/molecules23102408.

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Oxazaborolidine catalyst (CBS catalyst) has been extensively used for catalytic borane reduction with a predictable absolute stereochemistry and high enantioselectivity. However, the use of isolated CBS catalyst sometimes has the drawback of low reproducibility due to the aging of the CBS catalyst during storage. Therefore, we investigated a more reliable and practical method for the reduction of a variety of ketones including challenging substrates, primary aliphatic ketones, α,β-enones, and trifluoromethyl ketones. This review surveys the developments in borane reduction using oxazaborolidine catalysts generated in situ from chiral lactam alcohols and borane.

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8

Khandavalli, Sunilkumar, Jaehyung Park, Robin Rice, Guido Bender, Deborah J. Myers, Michael Ulsh, and Scott A. Mauger. "Tuning the Rheology of Anode Inks with Aging for Low-Temperature Polymer Electrolyte Membrane Water Electrolyzers." ECS Meeting Abstracts MA2022-02, no. 40 (October 9, 2022): 1483. http://dx.doi.org/10.1149/ma2022-02401483mtgabs.

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Low-temperature polymer electrolyte membrane water electrolyzers (PEMWE) are an attractive clean energy technology to produce hydrogen (H2), which is an energy carrier for several applications such as transportation and grid-scale energy storage and distribution (as supported by the US Department of Energy’s H2@Scale initiative). The catalyst layers -- composed of catalyst particles and ionomer, which acts as a binder for the catalyst and a proton conducting medium -- are key components of the PEMWE membrane electrode assembly (MEA). The catalyst layers are commonly fabricated by solution-processing an ink, which is a mixture of catalyst and ionomer often dispersed in a water-alcohol solvent mixture. Tuning the rheological properties of the anode inks (typically composed of iridium oxide catalyst, IrOx), particularly increasing their viscosity without significantly increasing the solids loading, to suit various scalable coating methods, is generally a challenge due to relatively low porosity and high density of the IrOx catalysts compared to the carbon-supported cathode catalysts. The typically low viscosities of the anode inks combined with high particle densities often cause stability/settling issues and challenges obtaining unform coatings, leading to inhomogeneous distribution of the catalyst that may have a negative effect on electrode performance. In this presentation we report on a dramatic enhancement in the viscoelasticity of the anode inks with aging, where the ink transitions from a liquid-like to a weak gel-like structure. The steady-shear and oscillatory shear rheology characterizations of the inks as a function of aging/time, the impact of formulation conditions (ionomer-to-catalyst ratio and dispersion media composition) on the viscoelastic enhancement with aging, and possible mechanisms for the observed behavior will be discussed. In addition to the rheological measurements, X-ray scattering characterization of the ink structure will be presented. The implications of the rheological changes on ink stability and processing will also be discussed. Additionally the impact of ink age on MEA performance will be presented.

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9

Zhao, Hong Xia, and Hai Liang Lü. "Study of Co/ZrO₂ Catalysts in Fischer-Tropsch Synthesis." Advanced Materials Research 850-851 (December 2013): 120–23. http://dx.doi.org/10.4028/www.scientific.net/amr.850-851.120.

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The investigation has been conducted to establish the effect of preparation methods on the textural properties, the metal-support interaction of the Co/ZrO2 catalysts and consequently its influence on Fischer-Tropsch synthesis. Coprecipitated Co/ZrO2 catalyst showed the strongest cobalt-zirconia interaction, the lowest reduction degree, and the lowest catalytic activity. Impregnated Co/ZrO2 catalyst showed the weakest cobalt-zirconia interaction, the highest reduction degree and the highest catalytic activity, while Co/ZrO2 catalyst prepared by directly impregnation Zr (OH)4 with cobalt nitrate solution were in the middle of CZC and CZI. The differences among the three catalysts could be ascribed to the different aging time of the support.

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10

Jiang, J. C., X. Q. Pan, G. W. Graham, R. W. McCabe, and J. Schwank. "Transmission Electron Microscopy Studies of Pd Encapsulation by Ceria-Zirconia Oxides." Microscopy and Microanalysis 4, S2 (July 1998): 724–25. http://dx.doi.org/10.1017/s1431927600023746.

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High-temperature catalysts containing Pd supported on high-surface area ceria-zirconia are optimum materials for fuel economy when automotive engines operate under high speed or load conditions. A prerequisite for developing such thermally stable catalysts is to gain a good understanding of the thermal deactivation modes contributing to the aging and degradation of catalysts in harsh thermal environments. It was discovered by X-ray diffraction that upon hightemperature aging, Pd may sinter into large (about 10 nm diameter) particles and become encapsulated in the ceria-zirconia. To confirm this conclusion, a prototype high-temperature catalyst containing Pd supported on high-surface area ceria-zirconia, aged at temperature above 1100 °C is studied by transmission electron microscopy (TEM).The ceria-zirconia supported Pd (0.25 wt%) catalyst was aged at 1105 °C and calcined at 700 °C for 2 h. For TEM sample preparations, first of all, a large-size aggregate with diameter about 1 mm was selected and sandwiched between by two pieces of silicon crystal.

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11

Merrell, Caroline P., and James F. Harbertson. "Sulfur Dioxide Management during Aging Is an Important Factor for the Development of Rosé Wine Color." Catalyst: Discovery into Practice 1, no. 3 (September 15, 2017): 80–87. http://dx.doi.org/10.5344/catalyst.2017.17003.

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12

Yang, Yunjie, Minli Bai, Laisuo Su, Jizu Lv, Chengzhi Hu, Linsong Gao, Yang Li, Yubai Li, and Yongchen Song. "One-Dimensional Numerical Simulation of Pt-Co Alloy Catalyst Aging for Proton Exchange Membrane Fuel Cells." Sustainability 14, no. 18 (September 13, 2022): 11462. http://dx.doi.org/10.3390/su141811462.

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The service life of catalysts is a key aspect limiting the commercial development of proton exchange membrane fuel cells (PEMFCs). In this paper, a one-dimensional degradation model of a Pt-Co alloy catalyst in the cathode catalytic layer (CCL) of a PEMFC is proposed, which can track the catalyst size evolution in real time and demonstrate the catalyst degradation during operation. The results show that severe dissolution of particles near the CCL/membrane leads to uneven aging of the Pt-Co alloy catalyst along the CCL thickness direction. When the upper potential limit (UPL) is less than 0.95 V, it does not affect the catalyst significantly; however, a slight change may cause great harm to the catalyst performance and service life after UPL > 0.95 V. In addition, it is found that operating temperature increases the Pt mass loss on the carbon support near the CCL/membrane side, while it has little effect on the remaining Pt mass on the carbon support near the CCL/GDL side. These uncovered degradation mechanisms of Pt-Co alloy provide guidance for its application in PEMFCs.

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13

Mirzaei, Ali A., Maryam Galavy, and Vahid Eslamimanesh. "SEM and BET Methods for Investigating the Structure and Morphology of Co - Ce Catalysts for Production of Light Olefins." Australian Journal of Chemistry 61, no. 2 (2008): 144. http://dx.doi.org/10.1071/ch07130.

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Co–Ce catalysts prepared by the coprecipitation method were tested for production of light olefins. The effect of different preparation conditions including the [Co]/[Ce] molar ratio, aging time, calcination conditions, different supports, and loading of optimum support on the structure and catalytic performance of different catalysts were investigated. It was found that catalyst containing 80% Co/20% Ce/15% SiO2, which was aged for 2 h and calcined at 600°C for 6 h, is the optimum modified catalyst for the conversion of synthesis gas to light olefins. Characterization of both precursors and calcined catalysts (before and after the test) was carried out using scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) specific surface area measurements. The morphology of the catalysts was investigated by SEM and the surface areas of these catalysts were studied by BET. It was shown that all of the different preparation variables influenced the morphology and also the specific surface area of the catalyst precursors and calcined catalysts.

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14

Jouini, Houda, Alessandra de Marcos-Galán, Imène Mejri, Rahma Bensouilah, Mourad Mhamdi, Teresa Blasco, and Gérard Delahay. "Understanding the Catalytic Deactivation upon Hydrothermal Aging at 850 °C of WO3/Fe-Cu-ZSM-5 Catalyst for Selective Catalytic Reduction of NO by NH3." Inorganics 10, no. 11 (October 25, 2022): 180. http://dx.doi.org/10.3390/inorganics10110180.

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A WO3/Fe-Cu-ZSM-5 catalyst was prepared using the solid state ion exchange method (SSIE) and its performance for the Selective Catalytic Reduction of NO with NH3 (NH3-SCR of NO) was investigated. The study shows that the tungsten addition can slightly improve the high temperature catalytic activity of Fe-Cu-ZSM-5. The influence of hydrothermal aging at 850 °C for 5 h on the structural and textural properties of WO3/Fe-Cu-ZSM-5 was also studied in this paper. The XRD and FE-SEM measurements did not indicate a breakdown of the zeolite structure upon steam treatment for both aged catalysts. The aged W-base catalyst demonstrates a lower deactivation and better catalytic activity for NO reduction than the bimetallic catalyst after hydrothermal aging despite the lower acidic properties as shown by FTIR-Pyr spectroscopy owing to the presence of tungsten oxide crystallites. The “severe” stage of aging occurring in the absence of W led to the formation of copper oxide agglomerates detected using STEM and H2-TPR techniques being responsible for the deterioration of SCR activity of the aged Fe-Cu-ZSM-5.

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15

Auvray, Xavier, and Anthony Thuault. "Effect of Microwave Drying, Calcination and Aging of Pt/Al2O3 on Platinum Dispersion." Catalysts 8, no. 9 (August 26, 2018): 348. http://dx.doi.org/10.3390/catal8090348.

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The effect of heating method employed for drying and calcination during the synthesis of 1 wt% Pt/Al2O3 catalyst was investigated. Conventional heating (CH) in resistive oven and microwave heating (MW) in single mode were applied, and the Pt dispersion and Brunauer-Emmett-Teller (BET) surface area were measured to characterize the samples. It was evidenced that the fast and homogeneous heating offered by the microwave heating led to higher Pt dispersion. However, this benefit was only achieved when the subsequent calcination was performed in a conventional oven. The aging in microwave oven of conventionally prepared—as well as MW-prepared—catalysts demonstrated the great ability of microwave irradiation to accelerate platinum sintering. After 1 h at 800 °C under microwave, catalysts showed a dispersion of 5%. Therefore, microwave treatment should be considered for accelerated catalyst aging but should be avoided as a calcination technique for the synthesis of highly dispersed Pt/Al2O3.

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16

Bukhtiyarova, Marina V., Olga A. Bulavchenko, Andrey V. Bukhtiyarov, Alexey L. Nuzhdin, and Galina A. Bukhtiyarova. "Selective Hydrogenation of 5-Acetoxymethylfurfural over Cu-Based Catalysts in a Flow Reactor: Effect of Cu-Al Layered Double Hydroxides Synthesis Conditions on Catalytic Properties." Catalysts 12, no. 8 (August 10, 2022): 878. http://dx.doi.org/10.3390/catal12080878.

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Cu-containing layered double hydroxides (LDHs) were synthesized by a co-precipitation method at different reaction conditions, such as aging time, pH, precipitation rate and synthesis temperature. The effect of these parameters on the structure and chemical composition of the catalysts were investigated using a set of physical methods, including thermogravimetric analysis (TGA), X-ray diffraction (XRD), H2-TPR and in situ X-ray photoelectron spectroscopy (XPS). It allowed for checking of the reducibility of the samples. 5-Acetoxymethylfurfural was catalytically hydrogenated to 5-(acetoxymethyl)-2-furanmethanol (AMFM) over Cu-containing catalysts synthesized from layered double hydroxides so as to investigate its catalytic properties in flow reaction. It was shown that synthesis pH decreasing from 10 to 8 resulted in rise of AMF conversion that coincided with the higher surface Cu/Al ratio obtained by XPS. Preferable aging time of LDH materials for obtaining the most active catalyst was 2 h, an amount of time that favored the production of the catalyst with high surface Cu/Al ratio up to 0.38. Under optimized reaction conditions, the AMFM yield was 98%. Finally, a synthesis strategy for the preparation of highly efficient Cu-based hydrogenation catalyst with optimized characteristics is suggested.

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17

Tam, P. S., J. W. Eldridge, and J. R. Kittrell. "Band-aging catalyst deactivation: Analytical solutions." AIChE Journal 32, no. 7 (July 1986): 1205–7. http://dx.doi.org/10.1002/aic.690320718.

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18

Friberg, Ida, Aiyong Wang, and Louise Olsson. "Hydrothermal Aging of Pd/LTA Monolithic Catalyst for Complete CH4 Oxidation." Catalysts 10, no. 5 (May 7, 2020): 517. http://dx.doi.org/10.3390/catal10050517.

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Palladium-based catalysts are known to provide high CH4 oxidation activity. One drawback for these materials is that they often lose activity in the presence of water vapor due to the formation of surface hydroxyls. It is however possible to improve the water vapor tolerance by using zeolites as support material. In this study, we have investigated Pd supported on thermally stable LTA zeolite with high framework Si/Al ratio (Si/Al = ~44) for CH4 oxidation and the effect of hydrothermal aging at temperatures up to 900 °C. High and stable CH4 oxidation activity in the presence of water vapor was observed for Pd/LTA after hydrothermal aging at temperatures ≤ 700 °C. However, aging at temperatures of 800–900 °C resulted in catalyst deactivation. This deactivation was not a result of structural collapse of the LTA zeolite as the LTA zeolite only showed minor changes in surface area, pore volume, and X-ray diffraction pattern after 900 °C aging. We suggest that the deactivation was caused by extensive formation of ion-exchanged Pd2+ together with Pd sintering. These two types of Pd species appear to have lower CH4 oxidation activity and to be more sensitive to water deactivation compared to the well dispersed Pd particles observed on the LTA support prior to the hydrothermal aging. By contrast, Pd/Al2O3 was generally sensitive to water vapor no matter of the aging temperature. Although the aging caused extensive Pd sintering in Pd/Al2O3, only minor deterioration of the CH4 oxidation activity was seen. The results herein presented show that Pd/LTA is a promising CH4 oxidation catalyst, however Pd rearrangement at high temperatures (≥800 °C) is one remaining challenge.

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19

Yang, Yi, Jia Fang, Junfeng Huang, Zihan Qin, Qian Zhang, Ping Pu, and Suozhu Pan. "Influence of Different Thermal Aging Conditions on Soot Combustion with Catalyst by Thermogravimetric Analysis." Materials 14, no. 13 (June 30, 2021): 3647. http://dx.doi.org/10.3390/ma14133647.

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Diesel particulates are deposited in the diesel particulate filter and removed by the regeneration process. The Printex-U (PU) particles are simulated as the diesel soot to investigate the influence of thermal aging conditions on soot combustion performance with the addition of catalysts. The comprehensive combustion index S, combustion stability index Rw and peak temperature Tp are obtained to evaluate the combustion performance. Compared with the PU/Pt mixtures of different Pt contents (2 g/ft3, 3.5 g/ft3, and 5 g/ft3), the 10 g/ft3 Pt contents improve soot combustion with the outstanding oxygen absorption ability. When the weight ratio of PU/Pt mixture is 1:1, the promoted effect achieves the maximum degree. The S and Rw increase to 8.90 × 10−8 %2min−2°C−3 and 39.11 × 105, respectively, compared with pure PU. After the thermal aging process, the PU/Pt mixture with a 350 °C aging temperature for 10 h promotes the soot combustion the best when compared to pure PU particles. It is not good as the PU/Pt mixture without aging, because the inner properties of soot and Pt/Al2O3 catalyst may have been changed. The S and Rw are 9.07 × 10−8 %2min−2°C−3 and 38.39 × 105, respectively, which are close to the no aging mixture. This work plays a crucial role in understanding the mechanism of the comprehensive effect of soot and catalyst on soot combustion after the thermal aging process.

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20

Sikhwivhilu, Dr Lucky, and Dr Venkataraman Vishwanathan. "Titanate Nanotubes as Futuristic Catalyst Support Material." International Journal of Innovative Technology and Exploring Engineering 10, no. 12 (October 30, 2021): 24–27. http://dx.doi.org/10.35940/ijitee.k9488.10101221.

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Titanate Nanotubes (TNT) were synthesized by aging commercial titanium dioxide (TiO2 - Degussa P25) with an alkali (KOH) solution at different time intervals. The prepared materials were investigated for their surface composition and textural behaviour by X-ray powder diffraction (XRD), Raman spectroscopy, Gas (N2 and CO2) adsorption measurements, and Transmission electron microscopy (TEM). The X-ray diffraction spectra revealed the decrease in the crystalline nature of the materials decreased by exposing them for a longer duration in the base solution. Raman spectra results showed that ageing time affected the structural properties. The specific surface area and the pore size of the newly synthesised materials were affected by the ageing process. The TEM images showed the influence of ageing during the formation of titanate nanotubes. HRTEM revealed that Pd particle sizes of <1 nm was present inside the tubes.

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Sikhwivhilu, Dr Lucky, and Dr Venkataraman Vishwanathan. "Titanate Nanotubes as Futuristic Catalyst Support Material." International Journal of Innovative Technology and Exploring Engineering 10, no. 12 (October 30, 2021): 24–27. http://dx.doi.org/10.35940/ijitee.l9549.10101221.

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Titanate Nanotubes (TNT) were synthesized by aging commercial titanium dioxide (TiO2 - Degussa P25) with an alkali (KOH) solution at different time intervals. The prepared materials were investigated for their surface composition and textural behaviour by X-ray powder diffraction (XRD), Raman spectroscopy, Gas (N2 and CO2) adsorption measurements, and Transmission electron microscopy (TEM). The X-ray diffraction spectra revealed the decrease in the crystalline nature of the materials decreased by exposing them for a longer duration in the base solution. Raman spectra results showed that ageing time affected the structural properties. The specific surface area and the pore size of the newly synthesised materials were affected by the ageing process. The TEM images showed the influence of ageing during the formation of titanate nanotubes. HRTEM revealed that Pd particle sizes of <1 nm was present inside the tubes.

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22

Park, Young-Kwon, Muhammad Zain Siddiqui, Sangjae Jeong, Eun-Suk Jang, and Young-Min Kim. "Catalytic Pyrolysis of Seawater Aged Polypropylene Over HZSM-5, HY, and Al-MCM-41." Journal of Nanoscience and Nanotechnology 21, no. 7 (July 1, 2021): 3971–74. http://dx.doi.org/10.1166/jnn.2021.19199.

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The effect of seawater aging on the thermal and catalytic pyrolysis of polypropylene (PP) was investigated using a thermogravimetric analyzer and pyrolyzer-gas chromatography/mass spectrometry. Although the surface properties of PP were of the oxidized form by seawater aging, the decomposition temperature and non-catalytic pyrolysis products of PP were relatively unchanged largely due to seawater aging. The catalytic pyrolysis of seawater-aged PP over all the catalysts produced smaller amounts of aromatic hydrocarbons than that of fresh PP due to catalyst poisoning caused by the residual inorganics. Among the catalysts, microporous HZSM-5 (SiO2/Al2O3:23) produced the largest amount of aromatic hydrocarbons followed in order by microporous HY(30) and nanoporous Al-MCM-41(20) from seawater-aged PP due to the high acidity and appropriate pore size for the generation of aromatic hydrocarbons.

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23

Auvray, Mihai, Lundberg, and Olsson. "Deactivation of Cu/SSZ-13 NH3-SCR Catalyst by Exposure to CO, H2, and C3H6." Catalysts 9, no. 11 (November 6, 2019): 929. http://dx.doi.org/10.3390/catal9110929.

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Lean nitric oxide (NOx)-trap (LNT) and selective catalytic reduction (SCR) are efficient systems for the abatement of NOx. The combination of LNT and SCR catalysts improves overall NOx removal, but there is a risk that the SCR catalyst will be exposed to high temperatures and rich exhaust during the LNTs sulfur regeneration. Therefore, the effect of exposure to various rich conditions and temperatures on the subsequent SCR activity of a Cu-exchanged chabazite catalyst was studied. CO, H2, C3H6, and the combination of CO + H2 were used to simulate rich conditions. Aging was performed at 800 °C, 700 °C, and, in the case of CO, 600 °C, in a plug-flow reactor. Investigation of the nature of Cu sites was performed with NH3-temperature-programed desorption (TPD) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) of probe molecules (NH3 and NO). The combination of CO and H2 was especially detrimental to SCR activity and to NH3 oxidation. Rich aging with low reductant concentrations resulted in a significantly larger deactivation compared to lean conditions. Aging in CO at 800 °C caused SCR deactivation but promoted high-temperature NH3 oxidation. Rich conditions greatly enhanced the loss of Brønsted and Lewis acid sites at 800 °C, indicating dealumination and Cu migration. However, at 700 °C, mainly Brønsted sites disappeared during aging. DRIFT spectroscopy analysis revealed that CO aging modified the Cu2+/CuOH+ ratio in favor of the monovalent CuOH+ species, as opposed to lean aging. To summarize, we propose that the reason for the increased deactivation observed for mild rich conditions is the transformation of the Cu species from Z2Cu to ZCuOH, possibly in combination with the formation of Cu clusters.

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Mirzaei, Ali A., Samaneh Vahid, and Mostafa Feyzi. "Fischer-Tropsch Synthesis over Iron Manganese Catalysts: Effect of Preparation and Operating Conditions on Catalyst Performance." Advances in Physical Chemistry 2009 (November 19, 2009): 1–12. http://dx.doi.org/10.1155/2009/151489.

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Анотація:

Iron manganese oxides are prepared using a coprecipitation procedure and studied for the conversion of synthesis gas to light olefins and hydrocarbons. In particular, the effect of a range of preparation variables such as [Fe]/[Mn] molar ratios of the precipitation solution, pH of precipitation, temperature of precipitation, and precipitate aging times was investigated in detail. The results are interpreted in terms of the structure of the active catalyst and it has been generally concluded that the calcined catalyst (at 650 for 6 hours) containing 50%Fe/50%Mn-on molar basis which is the most active catalyst for the conversion of synthesis gas to light olefins. The effects of different promoters and supports with loading of optimum support on the catalytic performance of catalysts are also studied. It was found that the catalyst containing 50%Fe/50%Mn/5 wt.% is an optimum-modified catalyst. The catalytic performance of optimal catalyst has been studied in operation conditions such as a range of reaction temperatures, /CO molar feed ratios and a range of total pressures. Characterization of both precursors and calcined catalysts is carried out by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), BET specific surface area and thermal analysis methods such as TGA and DSC.

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25

Shen, Zhi Bing, Ming Ke, Pei Yu, Shi Da Liu, Zhao Zheng Song, and Qing Zhe Jiang. "Study on Mo-Ni/Al₂O₃ Catalyst for Conversion of Mercaptans in the FCC Gasoline." Advanced Materials Research 550-553 (July 2012): 347–53. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.347.

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Анотація:

A Mo-Ni/Al2O3catalyst for converting mercaptans into thioethers to remove the mercaptans in the FCC gasoline was studied. Under the optimized conditions, the catalyst showed its good catalytic reaction performance and the activity remained stable after the 1500 h life experiment. After the accelerated aging experiment under severe conditions, the catalyst finally lost its activity at 1850 h. The samples of the fresh and used catalyst were characterized by BET, TEM and XPS. The results showed that the binding energy of sulfided Ni species shifted to the low energy level indicated that the sulfided Ni species might have a reducible tendency in the catalytic run. This could be considered as a main reason of the catalysts deactivation. On the other hand, the metal agglomeration and carbon deposition and nitrides adsorption in the catalytic runs also led to the deterioration of the catalyst.

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Alharbi, Khadijah H., Ali Alsalme, Ahmed Bader A. Aloumi, and Mohammed Rafiq H. Siddiqui. "Selective Catalytic Oxidation of Toluene to Benzaldehyde: Effect of Aging Time and Calcination Temperature Using CuxZnyO Mixed Metal Oxide Nanoparticles." Catalysts 11, no. 3 (March 9, 2021): 354. http://dx.doi.org/10.3390/catal11030354.

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Oxidation is an important organic transformation, and several catalysts have been reported for this conversion. In this study, we report the synthesis of mixed metal oxide CuxZnyO, which is prepared by a coprecipitation method by varying the molar ratio of Cu and Zn in the catalytic system. The prepared mixed metal oxide CuxZnyO was evaluated for catalytic performance for toluene oxidation. Various parameters of the catalytic evaluation were studied in order to ascertain the optimum condition for the best catalytic performance. The results indicate that aging time, calcination temperature, reaction temperature, and feed rate influence catalytic performance. It was found that the catalyst interfaces apparently enhanced catalytic activity for toluene oxidation. The XRD diffractograms reveal the crystalline nature of the mixed metal oxide formed and also confirm the coexistence of hexagonal and monoclinic crystalline phases. The catalyst prepared by aging for 4 h and calcined at 450 °C was found to be the best for the conversion of toluene to benzaldehyde while the reactor temperature was maintained at 250 °C with toluene fed into the reactor at 0.01 mL/min. The catalyst was active for about 13 h.

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Wang, Yan, Zhaoqiang Li, Rongrong Fan, Xin Guo, Cheng Zhang, Yu Wang, Zhiyong Ding, Rong Wang, and Wei Liu. "Deactivation and Regeneration for the SO2-Poisoning of a Cu-SSZ-13 Catalyst in the NH3-SCR Reaction." Catalysts 9, no. 10 (September 24, 2019): 797. http://dx.doi.org/10.3390/catal9100797.

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Анотація:

Cu-SSZ-13 has been generally considered as the predominant commercial selective catalytic reduction (SCR) catalyst in the NH3-SCR reaction because of its superior activity and durability. However, in real applications, SCR catalysts readily undergo hydrothermal aging and sulfur poisoning. In this work, the deactivation and regeneration of a commercial Cu-SSZ-13 catalyst was investigated for SO2 exposures during hydrothermal aging and the effect of different regeneration temperatures was compared. By using XRD, SEM, H2-temperature programmed reduction (TPR), X–ray photoelectron spectra (XPS) and NH3-temperature programmed desorption (TPD) analysis, it was found that SO2 poisoning influenced the chabazite (CHA) structure even if regeneration cannot restore its original structure, the redox ability and ammonia storage performance also influenced by sulfation and the regeneration process. Moreover, the extent of a decrease in redox ability was more severe than acidity, suggesting that the amount of isolated Cu2+ and Cu+ reduction was responsible for irreversible deactivation over the Cu-SSZ-13 catalyst. Combined with the analysis of Ea values and pre-exponential factor of the SCR reaction, a more likely explanation for the irreversible deactivation was that active sites were lost mostly in sulfated and regenerated process sites.

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Yu, Tian, Kai Li, Qian Wu, Peng Yao, Jia Ke, Bowen Wang, and Yanjun Wang. "Diesel Engine Emission Aftertreatment Device Aging Mechanism and Durability Assessment Methods: A Review." Atmosphere 14, no. 2 (February 4, 2023): 314. http://dx.doi.org/10.3390/atmos14020314.

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Анотація:

To meet more and more stringent emission standards, the combined technologies must be used to purify the emission pollutants of vehicle exhaust. Among them, the aftertreatment devices, including DOC, SCR, DPF, and so on, are the most efficient methods. However, after long-term running, the performance of the aftertreatment devices will inevitably degrade. There are several mechanisms that can be used to explain the aging phenomena. For the catalytic devices, such as DOC and SCR, thermal aging and poisoning aging are the most important reasons for their performance deterioration. As for DPF, ash clogging is a key problem for its stable working. To develop and test aftertreatment devices better and faster, the accelerated aging methods must be researched and applied. The small-sample aging method enables accelerated aging of catalyst samples at a very low cost, but its aging accuracy may not be good enough. Although the results of the whole-vehicle aging method and bench engine aging method are more in accord with the real using course, they take too much time and are too expensive to be used widely. Burner aging is a promising way to simulate the long-term running of the catalysts.

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Airun, Nurul Hidayati, Zukhrufi Zukhrufi, and Febi Indah Fajarwati. "STUDY OF THE EFFECT OF SOLVENT AND QUANTITY OF CATALYST ON ARICRYL POLYMERIZATION AT PT. ARISTEK HIGHPOLYMER BEKASI." INDONESIAN JOURNAL OF CHEMICAL RESEARCH 5, no. 2 (November 5, 2020): 51–60. http://dx.doi.org/10.20885/ijcr.vol5.iss2.art2.

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Aricryl synthesis was carried out by feeding technique. The monomers used were styrene, isobutyl acrylate, 2-HEMA and acrylamide powder. The catalysts used were AIBN (Azobisisobutyronitrile) and Perbutyl O98. The synthesis results were then devided by 2 for resin batch G-0915 A was diluted in > 63% mixture of n-butanol and methanol, while for G-0915 B was carried out dilution in > 63% toluene. the results obtained were compared based on the influence of the solvent using the parameters of viscosity, NV/total solid, AV (Acid Value), color and OH value. It was found that the best solvent according to specifications is toluene solvent with a viscosity of Z2-15. The Aricryl batch G-0915 was compared with Aricryl batch G-0903 based on the influence of the quantity of catalyst. The results showed that the increasing quantity of catalyst affects the aging process. Aging duration for Aricryl batch G-0903 was 11 hours, while for Arycril batch G-0915 was 8 hours.

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Xia, Yuzhen, Hangwei Lei, Chuanfu Sun, Xiaohao Wen, Zichen Wang, Guilin Hu, and Baizeng Fang. "Enhanced Ageing Performance of Sulfonic Acid-Grafted Pt/C Catalysts." Micromachines 13, no. 11 (October 26, 2022): 1825. http://dx.doi.org/10.3390/mi13111825.

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Анотація:

Chemical functionalization of carbon support for Pt catalysts is a promising way to enhance the performance of catalysts. In this study, Pt/C catalysts grafted with various amounts of phenylsulfonic acid groups were prepared under mild conditions. The influence of sulfonic acid groups on the physiochemical characteristics and electrochemical activities of the modified catalysts were studied using X-ray diffraction, X-ray photoelectron spectroscopy, a transmission electron microscope, and cyclic voltammetry (CV). The presence of the chemical groups enhanced the hydrogen adsorption onto/desorption off the Pt surface during the CV cycling. In contrast, the hydrogen peaks of the grafted catalysts increased after 500 CV cycles, especially for Pt (111) facets. The highest electrochemical surface area (ECSA) after the aging test was obtained for the catalyst with 18.0 wt.% graft, which was ca. 87.3% higher than that of the non-functionalized Pt catalyst. In the density functional theory (DFT) calculation, it was proven that SO3H adsorption on the crystalline was beneficial for Pt stability. The adsorption energy and bond distance of the adsorbed SO3H on Pt (110), (100), and (111) surfaces were calculated. All the stable configurations were obtained when O from S-O single bond or S was bound to the Pt surface, with the adsorption energy following the trend of (111)F > (100)H > (110)H. This result was consistent with the ECSA experiment, which explained the high electrochemical stability of the sulfonic acid groups-grafted Pt/C catalyst.

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Alikin, Evgeny A., Sergey P. Denisov, Konstantin V. Bubnov, and Aleksey A. Vedyagin. "Self-Regeneration Effect of Three-Way Catalysts during Thermal Aging Procedure." Catalysts 10, no. 11 (October 30, 2020): 1257. http://dx.doi.org/10.3390/catal10111257.

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Анотація:

One of the most important features of the three-way catalysts is their long-term stability. However, quite often, promising catalytic compositions with excellent activity become deactivated after a relatively short period of exploitation due to various reasons. Therefore, a study on the onboard regeneration of the deactivated three-way catalysts remains its actuality. The present work is mainly focused on the self-regeneration effect of the rhodium-containing component. Aging of the catalysts in the standard and model engine braking regimes revealed the difference in the catalytic performance. Deactivated rhodium species turned to the active state as a result of rapid cooling in air flow from 1200 to 600 °C. The regenerated catalyst shows improved activity towards NOx reduction and, therefore, widened operation window, which indicates higher accessibility of the rhodium species. X-ray diffraction analysis of the aged catalysts does not reveal any noticeable phase changes. Contrary, significant changes in the Rh oxidation state were registered by X-ray photoelectron spectroscopy. The observed effect opens new horizons for the development of the onboard purification systems with prolonged exploitation lifetime.

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Gao, Qi, Shuai Han, Qing Ye, Shuiyuan Cheng, Tianfang Kang, and Hongxing Dai. "Effects of Lanthanide Doping on the Catalytic Activity and Hydrothermal Stability of Cu-SAPO-18 for the Catalytic Removal of NOx (NH3-SCR) from Diesel Engines." Catalysts 10, no. 3 (March 17, 2020): 336. http://dx.doi.org/10.3390/catal10030336.

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Lanthanide (La, Ce, Nd, Gd, Tb, Ho or Lu)-doped Cu-SAPO-18 samples were prepared using the ion-exchange method. Physicochemical properties of the samples were systematically characterized by a number of analytical techniques, and the effects of lanthanide doping on catalytic activity and hydrothermal stability of the Cu-SAPO-18 catalysts for the NH3-SCR reaction were examined. It is shown that the doping of lanthanide elements could affect the interaction between the active components (copper ions) and the AEI-structured SAPO-18 support. The inclusion of some lanthanides significantly slowed down hydrolysis of the catalyst during hydrothermal aging treatment process, leading to an enhanced catalytic activity at both low and high temperatures and hydrothermal stability. In particular, Ce doping promoted the Cu2+ ions to migrate to the energetically favorable sites for enhancement in catalytic activity, whereas the other lanthanide ions exerted little or an opposite effect on the migration of Cu2+ ions. Additionally, Ce doping could improve hydrothermal stability of the Cu-SAPO-18 catalyst by weakening hydrolysis of the catalyst during the hydrothermal aging treatment process. Ce doping increased the catalytic activity of Cu-SAPO-18 at low and high temperatures, which was attributed to modifications of the redox and/or isolated Cu2+ active centers.

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Gao, Zhi Juan, Wei Ren Bao, Li Ping Chang, and Jian Cheng Wang. "In Situ Synthesis of Cu-SAPO-34/Cordierite with Ultrasonic Treatment and its Property of NOx Removal." Materials Science Forum 743-744 (January 2013): 449–54. http://dx.doi.org/10.4028/www.scientific.net/msf.743-744.449.

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Анотація:

A Cu-SAPO-34/cordierite monolithic catalyst was prepared by in-situ hydrothermal method. The effects of ultrasonic treatment were mainly investigated during the preparing process. The removal of NOX was evaluated using a fixed-bed reactor. X-ray diffraction, scanning electron microscopy were used to characterize the samples showing that the crystallinity of Cu-SAPO-34 molecular sieve have increased after ultrasonic treatment. The Cu-SAPO-34/cordierite prepared by ultrasonic treatment showed higher de-NOx activity and stronger anti-aging property. NOx conversion could reach more than 80% between 440 and 560°C over the fresh Cu-SAPO-34/cordierite catalyst with ultrasonic treatment (600 W, 2 h) and the highest conversion was 86%, however, the highest conversion was only 76% over the Cu-SAPO-34/cordierite catalyst without ultrasonic treatment. After aging (treated for 15 h at 720 °C in the presence of 200 ppm SO2 and 10% vapor), NOx conversion reached more than 45% between 400 and 520 °C over the catalyst with ultrasonic treatment and the highest conversion was 57%, however, the highest conversion was only 43% over the catalyst without ultrasonic treatment. The XRD and SEM results indicated that the structure and morphology of Cu-SAPO-34/cordierite monolithic catalyst kept in good condition after aging.

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Golubev, Georgy, Danila Bakhtin, Sergey Makaev, Ilya Borisov, and Alexey Volkov. "Hybrid Microporous Polymeric Materials with Outstanding Permeability and Increased Gas Transport Stability: PTMSP Aging Prevention by Sorption of the Polymerization Catalyst on HCPS." Polymers 13, no. 12 (June 9, 2021): 1922. http://dx.doi.org/10.3390/polym13121922.

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The influence of hyper-crosslinked polystyrene (HCPS) MacronetTM MN200 on the gas transport properties and aging of the highly permeable glassy polymer poly(1-trimethylsilyl-1-propyne) (PTMSP) was studied and analyzed in detail. The gas transport characteristics of dense PTMSP membranes containing 0–10.0 wt % HCPS were studied. It was shown that the introduction of a small amount of HCPS into the PTMSP matrix led to a 50–60% increase of the permeability coefficients of the material for light gases (N2, O2, CO2) and slowed down the deterioration of polymer transport properties over time. The lowest reduction in gas permeability coefficients (50–57%) was found for PTMSP containing HCPS 5.0 wt % after annealing at 100 °C for 300 h. It was found that HCPS sorbed residues of tantalum-based polymerization catalyst from PTMSP. In order to investigate the influence of catalysts on transport and physical properties of PTMSP, we purified the latter from the polymerization catalyst by addition of 5 wt % HCPS into polymer/chloroform solution. It was shown that sorption on HCPS allowed for almost complete removal of tantalum compounds from PTMSP. The membrane made of PTMSP purified by HCPS demonstrated more stable transport characteristics compared to the membrane made of the initial polymer. HCPS has a complex effect on the aging process of PTMSP. The introduction of HCPS into the polymer matrix not only slowed down the physical aging of PTMSP, but also reduced chemical aging due to removal of active reagents.

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Schröder, Jörg, Franziska Hartmann, Robert Eschrich, Denis Worch, Jürgen Böhm, Roger Gläser, and Franziska Müller-Langer. "Accelerated performance and durability test of the exhaust aftertreatment system by contaminated biodiesel." International Journal of Engine Research 18, no. 10 (April 3, 2017): 1067–76. http://dx.doi.org/10.1177/1468087417700762.

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Анотація:

The consumption of fossil and especially alternative fuels from renewable sources is supposed to rise in the future. Biofuels as well as fossil fuels often contain alkali and alkaline earth metal impurities that are potential poisons for automotive exhaust catalysts. The impact of these contaminations on the long-time performance of the exhaust aftertreatment system is a major concern. However, engine test bench studies consume considerable amounts of fuel, manpower and time. The purpose of this research project was to examine whether accelerated engine tests can be achieved by a modified diesel aftertreatment system in a test bench and contamination of biodiesel with known amounts of elements potentially poisoning automotive catalysts. A variety of potentially harmful elements (sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S) and phosphorous (P)) were added all at once to enhance the contamination level in biodiesel. A diesel oxidation catalyst and a catalyst for selective catalytic reduction reaction were placed in a stream of exhaust gas generated with a single cylinder engine. For reference purposes, a second test series was performed with a commercially available biodiesel. Catalysts were analyzed post-mortem using a bench flow reactor and X-ray fluorescence regarding their activity and deposition of the harmful elements. For both diesel oxidation catalyst and selective catalytic reduction catalysts, significant deactivation and decrease in conversion rates could be proven. For diesel oxidation catalyst, linear correlations between mass fractions of added elements and aging time were observed.

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Winkler, Alexander, Davide Ferri, Eth Panayotis Dimopoulos Eggenschwiler, and Myriam Aguirre. "Analysis techniques for diesel oxidation catalyst aging phenomena." MTZ worldwide 71, no. 6 (June 2010): 36–41. http://dx.doi.org/10.1007/bf03227023.

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Ramanathan, Karthik, and Se H. Oh. "Modeling and analysis of rapid catalyst aging cycles." Chemical Engineering Research and Design 92, no. 2 (February 2014): 350–61. http://dx.doi.org/10.1016/j.cherd.2013.06.020.

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Aguayo, Andres T., Ana G. Gayubo, Javier Ereña, Alaitz Atutxa, and Javier Bilbao. "Coke Aging and Its Incidence on Catalyst Regeneration." Industrial & Engineering Chemistry Research 42, no. 17 (August 2003): 3914–21. http://dx.doi.org/10.1021/ie030085n.

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Kenzhin, Roman M., Evgeny A. Alikin, Sergey P. Denisov, and Aleksey A. Vedyagin. "Study on Thermal Stability of Ceria-Supported Rhodium Catalysts." Materials Science Forum 950 (April 2019): 190–94. http://dx.doi.org/10.4028/www.scientific.net/msf.950.190.

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Анотація:

In the present work, the impact of the rhodium deposition on the thermal stability of ceria-based catalysts was studied. The samples were prepared by an incipient wetness impregnation of the support with aqueous solution of rhodium nitrate. The loading of Rh was 0.1 and 1 wt.%. The textural characteristics of the samples were examined by a low-temperature nitrogen adsorption. It was shown that the addition of rhodium intensifies the process of ceria agglomeration, which leads to the lower values of specific surface area along with increased average pore diameter after the aging at 1000 °C. Stability of the catalysts was investigated by means of a prompt thermal aging procedure. The high-loaded catalyst (1 wt.% Rh/CeO2) was more active than the 0.1 wt.% Rh/CeO2sample, while the stability of both the catalysts was excellent. It should be emphasized that the alumina-based reference samples with the similar rhodium loading were significantly less active and poorly stable.

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Mieczkowski, Paweł, Robert Jurczak, and Bartosz Budziński. "Asphalt concretes with metal-organic frameworks for highways and expressway road surfaces." Transportation Overview - Przeglad Komunikacyjny 2018, no. 11 (November 1, 2018): 85–93. http://dx.doi.org/10.35117/a_eng_18_11_09.

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Анотація:

The aim of performed research and analysis is the evaluation of the influence of metal-organic catalyst (MOC) on the properties of asphalt concretes designed for KR5-7 traffic load. The anhydrous iron (III) chloride was added as a metal-organic catalyst in the amount of 2,5% of asphalt mass. The study determined the properties of asphalt concrete with modified binder (70/100+2,5% FeCl3) and referential asphalt concrete with typical binder 35/50. The test included determination of water and freeze-thaw resistance (ITSR) and resistance to permanent deformation. Additional basic tests were performed to compare the properties of modifies, the 70/100 and 35/50 asphalt. The research was performed for three binder conditions: before aging, short-term aging in accordance with RTFOT and PAV long-term aging. The test results allowed to determine the IP penetration index. Additionally, for 35/50 asphalt and modified binder the dynamic viscosity was determined before and after aging in accordance with RTFOT. The addition of metal-organic catalyst increased the resistance of the asphalt concrete to permanent deformation without changing its water and freeze-thaw resistance. In case of the 70/100 asphalt the addition of MOC improved the hardness (especially after short- and long-term aging) and influenced the rheology.

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Gromotka, Zoë, Gregory Yablonsky, Nickolay Ostrovskii, and Denis Constales. "Three-Factor Kinetic Equation of Catalyst Deactivation." Entropy 23, no. 7 (June 27, 2021): 818. http://dx.doi.org/10.3390/e23070818.

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Анотація:

The three-factor kinetic equation of catalyst deactivation was obtained in terms of apparent kinetic parameters. The three factors correspond to the main cycle with a linear, detailed mechanism regarding the catalytic intermediates, a cycle of reversible deactivation, and a stage of irreversible deactivation (aging), respectively. The rate of the main cycle is obtained for the fresh catalyst under a quasi-steady-state assumption. The phenomena of reversible and irreversible deactivation are presented as special separate factors (hierarchical separation). In this case, the reversible deactivation factor is a function of the kinetic apparent parameters of the reversible deactivation and of those of the main cycle. The irreversible deactivation factor is a function of the apparent kinetic parameters of the main cycle, of the reversible deactivation, and of the irreversible deactivation. The conditions of such separability are found. The obtained equation is applied successfully to describe the literature data on the reversible catalyst deactivation processes in the dehydration of acetaldehyde over TiO2 anatase and in crotonaldehyde hydrogenation on supported metal catalysts.

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Wang, Meixin, Zhaoliang Peng, Changming Zhang, Mengmeng Liu, Lina Han, Yaqin Hou, Zhanggen Huang, Jiancheng Wang, Weiren Bao, and Liping Chang. "Effect of Copper Precursors on the Activity and Hydrothermal Stability of CuII−SSZ−13 NH3−SCR Catalysts." Catalysts 9, no. 9 (September 19, 2019): 781. http://dx.doi.org/10.3390/catal9090781.

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Анотація:

A series of CuII−SSZ−13 catalysts are prepared by in-situ hydrothermal method using different copper precursors (CuII(NO3)2, CuIISO4, CuIICl2) for selective catalytic reduction of NO by NH3 in a simulated diesel vehicle exhaust. The catalysts were characterized by X−ray diffraction (XRD), scanning electron microscope (SEM), X−ray photoelectron spectroscopy (XPS), N2 adsorption-desorption, hydrogen-temperature-programmed reduction (H2−TPR), ammonia temperature-programmed desorption (NH3−TPD), and 27Al and 29Si solid state Nuclear Magnetic Resonance (NMR). The CuII−SSZ−13 catalyst prepared by CuII(NO3)2 shows excellent catalytic activity and hydrothermal stability. The NO conversion of CuII−SSZ−13 catalyst prepared by CuII(NO3)2 reaches 90% at 180 °C and can remain above 90% at a wide temperature range of 180–700 °C. After aging treatment at 800 °C for 20 h, the CuII−SSZ−13 catalyst prepared by CuII(NO3)2 still exhibits above 90% NO conversion under a temperature range of 240–600 °C. The distribution of Cu species and the Si/Al ratios in the framework of the synthesized CuII−SSZ−13 catalysts, which determine the catalytic activity and the hydrothermal stability of the catalysts, are dependent on the adsorption capacity of anions to the cation during the crystallization process due to the so called Hofmeister anion effects, the NO3− ion has the strongest adsorption capacity among the three kinds of anions (NO3−, Cl−, and SO42−), followed by Cl– and SO42– ions. Therefore, the CuII−SSZ−13 catalyst prepared by CuII(NO3)2 possess the best catalytic ability and hydrothermal stability.

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Lei, Lili, Miaomiao Jin, Chenrui Cui, Kai Li, and Pan Wang. "Effects of the Reaction Parameters and Light Hydrothermal Aging for Catalytic Combustion of Propane over Co-Mn-Ce Catalyst." Journal of Chemistry 2022 (February 10, 2022): 1–9. http://dx.doi.org/10.1155/2022/4574887.

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Анотація:

A composite oxides’ Co-Mn-Ce catalyst was synthesized by a coprecipitation method, and the experiment was carried out to study the effects of reaction parameters and light hydrothermal aging on propane combustion over the Co-Mn-Ce catalyst. The influence of reaction temperature, propane concentration, oxygen concentration, water vapor, and hydrothermal aging was studied during the catalytic combustion of propane. The propane conversion significantly decreased by 10% when the propane concentration increased at 300°C and then further decreased from 80% to 40% as water vapor concentration increased from 0 to 10 vol.%. In addition, water vapor also prolonged the time required to reach equilibrium. After hydrothermal treatment, the catalyst obtained the lowest oxidation capacity of propane. Furthermore, the results of in situ DRIFTs and O2 temperature programmed desorption (O2-TPD) demonstrated that there were fewer oxygen species after hydrothermal aging, and carbonates were the main intermediates formed during the catalytic oxidation of propane.

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Donorfio, Laura. "PEDAGOGY OF AGING: A JOURNEY TOWARD AUTHENTICITY AND WHOLENESS." Innovation in Aging 6, Supplement_1 (November 1, 2022): 169. http://dx.doi.org/10.1093/geroni/igac059.672.

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Анотація:

Abstract Innovation in gerontological education has been a driving catalyst since the beginning of my career over 30 years ago. While sometimes seen as a curse, this catalyst has shaped my teaching pedagogy in unimaginable ways. Examples include field trips with 40+ students, developing an aging toolbox for students to make the material more concrete, creating a new interactive television teaching platform over multiple university campuses, developing experiential curriculum and an undergraduate minor in aging, and proudly, developing AGHE’s first teaching institute now in its 11th year. Unexpectedly, at this stage of my career, I have become very aware that my teaching about aging has intersected with my personal aging, shaping my personal pedagogy in profound ways--increased empathy, sensitivity, and social awareness. I am living the subject matter I thought I intimately knew. I am the other. Has my teaching been inauthentic? Hypocritical? Ageist? Please join me for a healthy discussion on how this insight can be leveraged to teach the next generation of aging scholars.

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Baik, Joon Hyun, Hyuk Jae Kwon, Yong Tak Kwon, In-Sik Nam, and Se H. Oh. "Effects of catalyst aging on the activity and selectivity of commercial three-way catalysts." Topics in Catalysis 42-43, no. 1-4 (May 2007): 337–40. http://dx.doi.org/10.1007/s11244-007-0201-3.

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46

Kim, Sooho. "Analytical electron microscopy of fresh and vehicle-aged catalysts." Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 714–15. http://dx.doi.org/10.1017/s0424820100105631.

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Automotive catalysts have a general loss of activity during aging, basically due to two principal deactivation mechanisms. One of them is thermally induced “sintering,” which results in catalytic surface area reduction. The other is chemically induced “poisoning,” which in part causes blockage of active metal sites. The conventional bulk techniques have indicated that various catalyst functions were affected differently by poisons and thermal damage; however, they generally did not provide detailed descriptions of the mechanisms of deactivation. Only analytical electron microscopy (AEM) can provide microchemical and microstructural information to gain a more thorough and fundamental understanding of catalytic deactivation.Fresh and vehicle-aged commercial automotive catalysts containing Pt, Pd, and Rh on alumina supports were prepared for AEM by a microtomy technique, which retains the spatial integrity of the catalyst pellet with uniform thickness. Then these AEM specimens were characterized in a transmission electron microscope (TEM) and in a dedicated scanning transmission electron microscope (STEM).

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47

Sadanandam, G., N. Sreelatha, M. V. Phanikrishna Sharma, S. Kishta Reddy, B. Srinivas, K. Venkateswarlu, T. Krishnudu, M. Subrahmanyam, and V. Durga Kumari. "Steam Reforming of Glycerol for Hydrogen Production over Ni/SiO2 Catalyst." ISRN Chemical Engineering 2012 (December 26, 2012): 1–10. http://dx.doi.org/10.5402/2012/591587.

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The performance of Ni/SiO2 catalyst for glycerol reforming has been investigated in fixed-bed reactor using careful tailoring of the operational conditions. In this paper, a commercial Engelhard catalyst has been sized and compared to gas product distribution versus catalyst size, water-to-carbon ratio, and stability of the catalyst system. Ni/SiO2 catalysts of three sizes (2×2, 2×4, and 3×5 mm) are evaluated using glycerol: water mixture at 600°C to produce 2 L H2 g−1 cat h−1. The results indicate that 3×5 mm size pellet is showing minimum coking and maintaining same level of conversion even after several hours of reforming activity. Whereas studies on 2×2 and 2×4 mm pellets indicate that carbon formation is affecting the reforming activity. Under accelerated aging studies, with 1 : 9 molar ratio of glycerol to water, 3 mg carbon g−1 cat h−1 was generated in 20 cycles, whereas 1 : 18 feed produced only 1.5 mg carbon g−1 cat h−1 during the same cycles of operation. The catalysts were characterized before and after evaluation by X-ray diffraction (XRD), BET surface area, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDAX), CHNS analysis, transmission electron microscopy (TEM), and X-ray photo electron spectroscopy (XPS).

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48

Chang, Zhixin, Jiajia Zhang, Weiqi Zhang, Huaneng Su, Lei Xing, Qiang Ma, Hong Zhang, and Qian Xu. "Enhanced Cell Performance and Improved Catalyst Utilization for a Direct Methanol Fuel Cell with an In-Plane Gradient Loading Catalyst Electrode." Processes 9, no. 10 (October 8, 2021): 1787. http://dx.doi.org/10.3390/pr9101787.

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Direct methanol fuel cells (DMFCs) offer high energy density, simple liquid fuel storage, and the ability to operate at ambient temperature. They may be used in a variety of portable mobile power supplies, small civilian power supplies, and automotive power supplies. However, in the process of electrochemical reaction inside a DMFC, because the reactants and products are distributed unevenly, the in-plane concentration of reactants and reaction rate are different; thus, the current density generated in the active area shows a high degree of non-uniformity. The high local current density can easily lead to the acceleration of DMFC aging. As a result, the operating cost of the DMFC is increased and the service life is shortened, which limits the commercial application of DMFCs. In this work, we develop an in-plane gradient loading catalyst. The loading on both the anode and cathode catalysts was lower near the inlet and higher close to the outlet. The experimental results of the single-cell test show that the performance of the gradient loading catalyst electrode was enhanced by up to 19.8% compared with the uniform loading catalyst at 60 °C for the same catalyst loading, especially under high current densities. In addition, the catalyst utilization was improved for the gradient loading catalyst electrode. Hence, the proposed approach shows potential for reducing the cost and increasing the service life of DMFCs.

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Valdez Lancinha Pereira, M., A. Nicolle, and D. Berthout. "Hydrothermal aging effects on Cu-zeolite NH3-SCR catalyst." Catalysis Today 258 (December 2015): 424–31. http://dx.doi.org/10.1016/j.cattod.2015.03.027.

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50

Salim, Belaid, Salem Fouad Chabira, Pascale Balland, Ahmed Maati, and M. Sebaa. "Thermal aging and catalyst concentration effects on thermo-dynamical and mechanical properties of a polyester fiberglass composite." Metallurgical and Materials Engineering 28, no. 1 (September 10, 2021): 125–39. http://dx.doi.org/10.30544/630.

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This work deals with the characterization by physicochemical and mechanical analysis performed on composite polyester fiberglass plates molded by contact and aged in thermo-stated ovens to simulate their deleterious environment of use. The DSC analysis revealed that the catalyst concentration affected the thermal behavior of the composite. Indeed, the addition of a higher catalyst concentration slightly lowered the glass transition temperature. From a mechanical point of view, it was observed that the catalyst addition made the material stiffer. The properties at fracture were also affected by the catalyst concentration and varied irregularly with aging.

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