scholarly journals Hybrid Cu-Fe/ZSM-5 Catalyst Prepared by Liquid Ion-Exchange for NOx Removal by NH3-SCR Process

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Tuan Doan ◽  
Anh Dang ◽  
Dat Nguyen ◽  
Thanh Huyen Vuong ◽  
Minh Thang Le ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Active Sites ◽  
Flow Reactor ◽  
Catalytic Reduction ◽  
Fixed Bed ◽  
Chemical Properties ◽  
Resonance Method ◽  
Exchange Method ◽  
Characterization Methods ◽  
Nh3 Scr

A series of Cu/ZSM-5, Fe/ZSM-5, and Cu-Fe/ZSM-5 catalysts (Si/Al in ZSM-5 = 25) were prepared by different metal loadings using the liquid ion-exchange method. Several characterization methods were conducted to explore the effects of metals on the physical and chemical properties of catalysts. Meanwhile, the electron paramagnetic resonance method is also used to assess the copper and/or iron elements’ coordination and valence state at intersections or in channels of ZSM-5. The metal-loading effects of all catalysts on the catalytic activities were studied for the removal of NOx in a fixed-bed flow reactor using selective catalytic reduction with ammonia (NH3-SCR). The results showed that the iron’s addition could markedly broaden the operation temperature range of the Cu/ZSM-5 catalyst for NH3-SCR between 200 and 550°C due to the presence of more isolated Cu2+ ions as well as additional oligomeric Fe3+ active sites and FexOy oligomeric species. This paper gives a facile and straightforward way to synthesize the practical-promising catalyst applied in NH3-SCR technology to control NOx emissions.

Influence of Aluminum Sources on Synthesis of SAPO-34 and NH3-SCR of NOx by as-Prepared Cu/SAPO-34 Catalysts

2020 ◽  
Vol 20 (5) ◽  
pp. 373
Author(s):  
Tuan Doan ◽  
Anh Dang ◽  
Dat Nguyen ◽  
Khanh Dinh ◽  
Phong Dam ◽  
...  
Keyword(s):  
Flow Reactor ◽  
Fixed Bed ◽  
Acid Sites ◽  
Hydrothermal Conditions ◽  
Exchange Method ◽  
Characterization Methods ◽  
Cu Content ◽  
Tetraethylammonium Hydroxide ◽  
Nh3 Scr ◽  
Scr Of Nox

The full article will be published in the English version of the  journal "Catalysis in Industry" No. 1, 2021.The synthesis of the microporous SAPO-34 molecular sieve goes from a combination of three templates: triethylamine, tetraethylammonium hydroxide, and morpholine under hydrothermal conditions. Two aluminum sources, namely aluminum hydroxide, and aluminum isopropoxide, were used exclusively to synthesize SAPO-34 zeolites. The effects of aluminum sources on the crystallization and physicochemical properties of SAPO-34 were studied thoroughly. The synthesized samples were characterized by using different characterization methods, including XRD, FE-SEM, N2 isotherm, EDS, and NH3-TPD. The results illustrate that the various sources of aluminum used for the synthesis of SAPO-34 materials extremely affect the crystallinity, morphology, and density of acid sites. Besides, the influence of aluminum sources on the performance of NH3-SCR technology was studied with Cu/SAPO-34 catalysts in a fixed-bed flow reactor. The two Cu/SAPO-34 catalysts promoted different NO and NH3 conversions between 200–600 °C though they share similar Cu content, which was loaded by the ion-exchange method in aqueous solution. In addition, the different Cu species in the two catalyst samples are surveyed by H2-TPR, while the EPR method is also used to assess the coordination of the copper element in the two catalysts.

scholarly journals Ultrasound-Assisted Preparation of Mo/ZSM-5 Zeolite Catalyst for Non-Oxidative Methane Dehydroaromatization

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 313
Author(s):  
Heidy Ramirez-Mendoza ◽  
Mafalda Valdez Lancinha Pereira ◽  
Tom Van Gerven ◽  
Cécile Lutz ◽  
Ignacio Julian
Keyword(s):  
Catalytic Activity ◽  
Ion Exchange ◽  
Active Sites ◽  
Chemical Properties ◽  
Successful Implementation ◽  
Metal Dispersion ◽  
Zeolite Framework ◽  
Dispersed Catalysts ◽  
Methane Dehydroaromatization ◽  
Ultrasound Assisted

The activity and selectivity of Mo/ZSM-5, benchmarking catalyst for the non-oxidative dehydroaromatization of methane, strongly depend on the cluster size, spatial distribution, and chemical environment of the Mo-based active sites. This study discloses the use of an ultrasound-assisted ion-exchange (US-IE) technique as an alternative Mo/ZSM-5 synthesis procedure in order to promote metal dispersion along the zeolite framework. For this purpose, a plate transducer (91.8 kHz) is employed to transmit the ultrasonic irradiation (US) into the ion-exchange reactor. The physico-chemical properties and catalytic activity of samples prepared under the said irradiation procedure and traditional impregnation (IWI) method are critically evaluated. Characterization results suggest that US neither affects the crystalline structure nor the particle size of the parent zeolite. However, US-IE promotes molybdenum species dispersion, avoids clustering at the external fresh zeolite surface and enhances molybdate species anchoring to the zeolite framework with respect to IWI. Despite the improved metal dispersion, the catalytic activity between catalysts synthesized by US-IE and IWI is comparable. This suggests that the sole initial dispersion enhancement does not suffice to boost the catalyst productivity and further actions such ZSM-5 support and catalyst pre-conditioning are required. Nevertheless, the successful implementation of US-IE and the resulting metal dispersion enhancement pave the way toward the application of this technique to the synthesis of other dispersed catalysts and materials of interest.

The role of various iron species in Fe-β catalysts with low iron loadings for NH3-SCR

2014 ◽  
Vol 4 (5) ◽  
pp. 1350-1356 ◽  
Author(s):  
Haiyan Liu ◽  
Jun Wang ◽  
Tie Yu ◽  
Shikuan Fan ◽  
Meiqing Shen
Keyword(s):  
Ion Exchange ◽  
Iron Species ◽  
Exchange Method ◽  
Nh3 Scr ◽  
Ion Exchange Method

A series of Fe-β catalysts, containing 0.17–0.52 wt% Fe, were prepared by a liquid ion-exchange method to study the influence of various iron species on NH3-SCR activity.

scholarly journals Influence of Impurity Dissolution on Surface Properties and NH3-SCR Catalytic Activity of Rare Earth Concentrate

Minerals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 246
Author(s):  
Zhang ◽  
Zhu ◽  
Zhang ◽  
Li ◽  
Luo ◽  
...  
Keyword(s):  
Rare Earth ◽  
Active Sites ◽  
Catalytic Effect ◽  
Catalytic Reduction ◽  
Weak Acid ◽  
Active Components ◽  
Catalyst Sample ◽  
Nh3 Scr ◽  
O2 Concentration ◽  
Alkali Leaching

Impurity removal and modification of rare earth concentrate powder were conducted by roasting weak acid-weak alkali leaching to obtain the active components of denitrification catalysts. NH3 selective catalytic reduction catalyst samples were prepared by mixing and kneading with pseudo-γ-Al2O3 boehmite as carrier. The results showed that the Ce7O12 content in the active component samples increased and dispersed more evenly. The grain size of the samples was refined, the specific surface area increased, and the active sites exposed more. Ce coexists in the form of Ce3+ and Ce4+. Fe coexists in the form of Fe3+ and Fe2+, but Fe3+ is abundant. Some Ce, La, Nd, Pr, Fe, Mn, and other components formed solid melts during preparation, which increased the synergistic catalytic effect. The denitrification efficiency of the catalyst sample was 92.8% under the conditions of reaction temperature 400 °C, NO content was 600 ppm, NH3/NO ratio was 1.5, and O2 concentration was 4%.

scholarly journals Effect of Ion-Exchange Sequences on Catalytic Performance of Cerium-Modified Cu-SSZ-13 Catalysts for NH3-SCR

Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 997
Author(s):  
Yan Wang ◽  
Zhaoqiang Li ◽  
Zhiyong Ding ◽  
Na Kang ◽  
Rongrong Fan ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Copper Ions ◽  
Reduction Process ◽  
Catalytic Performance ◽  
Adsorbed Species ◽  
Exchange Method ◽  
Coordination Environment ◽  
Nh3 Scr ◽  
Nox Conversion ◽  
Acidic Sites

Cerium-modified Cu-SSZ-13 catalysts were prepared by an aqueous ion-exchange method, and Ce and Cu were incorporated through different ion-exchange sequences. The results of NH3-SCR activity evaluations displayed that Cu1(CeCu)2 catalyst presented excellent catalytic activity, and over 90% NOx conversion was obtained across the temperature range of 200–500 °C. The characterization results showed that the ion-exchange sequence of Cu and Ce species influenced the crystallinity of the zeolites and the coordination of Al. A small amount of Ce could participate in the reduction process and change the location and coordination environment of copper ions. Furthermore, Ce-modified Cu-SSZ-13 catalysts possessed more acidic sites due to their containing replacement of Ce and movement of Cu in the preparation process. The cooperation of strong redox abilities and NH3 storage capacity led to the increase of active adsorbed species adsorption and resulted in better activity of Cu1(CeCu)2.

scholarly journals Investigation of Butane-butylene Technical Mixtures Transformation Over Modified Microporous Materials Prepared by Ion Exchange Method Into Liquid Fraction Rich in Aromatic Hydrocarbons

2019 ◽  
Vol 70 (6) ◽  
pp. 2004-2009
Author(s):  
Iuliean Vasile Asaftei ◽  
Neculai Catalin Lungu ◽  
Maria Ignat ◽  
Ion Sandu
Keyword(s):  
Catalytic Activity ◽  
Ion Exchange ◽  
Atmospheric Pressure ◽  
Liquid Fraction ◽  
Fixed Bed ◽  
Space Velocity ◽  
Exchange Method ◽  
Structure Morphology ◽  
Stainless Steel Reactor ◽  
Ion Exchange Method

The Zn and Ni were introduced into HZSM-5 zeolite by ion exchange method with aqueous solutions of Zn(NO3)2 and Ni(NO3)2, to investigate the catalytic activity and selectivity of modified Zn-HZSM-5 and Ni-HZSM-5 catalysts for conversion of butane-butylenes technical mixtures in a fixed-bed stainless-steel reactor (Twin Reactor System Naky) at 450�C, at atmospheric pressure for Zn-HZSM-5 and at 4 atm. total pressure for Ni-HZSM-5 and at a space velocity (WHSV) of 1h-1. The catalysts were characterized using XRD, SEM, and NH3-TPD analysis for their structure, morphology and acidity. The catalytic activity of the same catalyst were examined during over 10 catalytic tests (with regeneration of catalyst after each test) using mixtures of butanes-butylenes.

scholarly journals Synthesis and characterization of Cu-MFI catalyst for the direct medium temperature range NO decomposition

2016 ◽  
Vol 34 (1) ◽  
pp. 177-184 ◽  
Author(s):  
Karolina Maduna Valkaj ◽  
Vesna Tomašić ◽  
Andrea Katović ◽  
ElżBieta Bielańska
Keyword(s):  
Ion Exchange ◽  
Active Sites ◽  
Catalytic Properties ◽  
Direct Synthesis ◽  
Copper Acetate ◽  
Nitrogen Adsorption ◽  
No Decomposition ◽  
Medium Temperature ◽  
Exchange Method ◽  
Mfi Zeolites

AbstractIn this study the physico-chemical and catalytic properties of copper bearing MFI zeolites (Cu-MFI) with different Si/Al and Si/Cu ratios were investigated. Two different methods for incorporation of metal ions into the zeolite framework were used: the ion exchange from the solution of copper acetate and the direct hydrothermal synthesis. Direct synthesis of a zeolite in the presence of copper-phosphate complexes was expected to generate more active copper species necessary for the desired reaction than the conventional ion exchange method. Direct decomposition of NO was used as a model reaction, because this reaction still offers a very attractive approach to NOX removal. The catalytic properties of zeolite samples were studied using techniques, such as XRD, SEM, EPR and nitrogen adsorption/desorption measurements at 77 K. Results of the kinetic investigation revealed that both methods are applicable for the preparation of the catalysts with active sites capable of catalyzing the NO decomposition. It was found out that Cu-MFI zeolites obtained through direct synthesis are promising catalysts for NO decomposition, especially at lower reaction temperatures. The efficiency of the catalysts prepared by both methods is compared and discussed.

Investigation on the stability of copper modification of SAPO-34 catalysts in NH3-SCR reaction after hydrothermal aging

2020 ◽  
Vol 98 (5) ◽  
pp. 236-243
Author(s):  
Xiaoxin Wu ◽  
Jiaxi Peng ◽  
Shaoming Yang ◽  
Wenyuan Xu
Keyword(s):  
Ion Exchange ◽  
Copper Oxide ◽  
Structural Stability ◽  
Solid State Nmr ◽  
Impregnation Method ◽  
Hydrothermal Aging ◽  
Exchange Method ◽  
Nh3 Scr ◽  
Ion Exchange Method ◽  
The Stability

The influence of hydrothermal aging on the structural stability of Cu-modified SAPO-34 prepared by ion-exchange and impregnation methods was studied. XRD, Ar adsorption at −196 °C, solid-state NMR, UV–vis, H2-TPR, and EPR were used to probe the structural properties of the catalysts. It was found that the precipitation of crystalline AlPO4 and SiO2, the appearance of mesopores, the migration of silicon to form siliceous islands, and the formation of copper oxide crystallites occurred in aged catalysts. Furthermore, more siliceous islands and copper oxide crystallites were present in the aged samples prepared by the impregnation method than in those prepared by the ion-exchange method. Therefore, the impregnated catalysts show a much poorer structural stability than the ion-exchanged catalysts, which leads to more serious deterioration in the NH3-SCR reaction after hydrothermal aging.

scholarly journals Deactivation of Cu/SSZ-13 NH3-SCR Catalyst by Exposure to CO, H2, and C3H6

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 929 ◽  
Author(s):  
Auvray ◽  
Mihai ◽  
Lundberg ◽  
Olsson
Keyword(s):  
Flow Reactor ◽  
Catalytic Reduction ◽  
Plug Flow ◽  
Acid Sites ◽  
Drift Spectroscopy ◽  
Scr Catalyst ◽  
Nh3 Scr ◽  
Scr Catalysts ◽  
Nh3 Oxidation ◽  
Diffuse Reflectance Infrared

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.

The Role of Ion Exchange Method of Na-ZSM-5 Zeolite and Influence Hydrogenation Components on Properties and Activity of Dewaxing Catalysts

1992 ◽  
Vol 57 (5) ◽  
pp. 969-977 ◽  
Author(s):  
Jolanta R. Grzechowiak ◽  
Aleksandra Masalska ◽  
Tadeusz Romotowski ◽  
Jolanta Komorek
Keyword(s):  
Low Temperature ◽  
Ion Exchange ◽  
Flow Reactor ◽  
Nitrate Solution ◽  
Diesel Oil ◽  
Ni Catalysts ◽  
Exchange Method ◽  
Oil Fraction ◽  
Ion Exchange Method

Hydrocracking of n-hexane and diesel oil fraction over presulfided NiMo, Mo and Ni catalysts has been carried out using a high pressure flow reactor system. The ion-exchanged form of ZSM-5 extrudates (50% alumina binder) was loaded with 2-20 wt.% of metals. The results indicate that, using Ni/H-ZSM-5 zeolite obtained by incorporation of nickel by ion exchange treatment of NH4-ZSM-5 from nickel nitrate solution, it is possible to obtain sufficiently active catalysts for low-temperature hydrocracking process. The catalysts containing Ni-ZSM-5 zeolites (Ni/H-ZSM-5 or Ni/Na-ZSM-5) were superior to catalyst prepared by using P/H-ZSM-5. It was found that nickel was an essential hydrogenation components of low temperature hydrocracking catalysts.

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