Effect of Preparation Mode on the Properties of Mn-Na-W/SiO2 Catalysts for Oxidative Coupling of Methane: Conventional Methods vs. POSS Nanotechnology

Reflectance spectroscopic methods the electronic, redox and structural properties of Mn-Na-W/SiO2 catalysts prepared by the incipient wetness impregnation method and mixture slurry method were studied in detail. Since POSS nanotechnology (POSS = polyhedral oligomeric silsesquioxanes) has attracted attention as tooling for synthesis of catalysts with novel properties and functionalities, we expanded this method for the preparation of Mn-Na-W/SiO2 catalyst. The physicochemical and catalytic properties of Mn-Na-W/SiO2 catalysts prepared by conventional methods and POSS nanotechnology were examined comparatively. In all studied Mn-Na-W/SiO2 catalysts both individual oxides (MnOx, WO3) and bimetal oxide phases (Na2WO4, MnWO4) are found in addition to oxide particles of high dispersion. The UV-Vis Diffuse Reflectance indicates that Na+ cations facilitates stabilization of octahedrally coordinated Mn3+Oh cations in the isolated state, while Mn3+Oh promote the disordering of W6+ cations in the supported system. The Mn-Na-W/SiO2 prepared using metal-POSS precursors marks out presence of unglobular SiO2 particles, higher dispersion of MnOx and MnWO4 particles and more easily reducible metal-oxide species. The catalysts prepared by incipient impregnation method and mixture slurry method have practically similar catalytic performance while the catalyst prepared by POSS nanotechnology method shows lower activity and selectivity. At 800‒850 °C the increase of C2 hydrocarbons yield from 4 to 15% and the rise of molar ratio С2Н4/C2H6 from 0.2 to 1 are observed when impregnation or mixture slurry method are used for catalyst preparation instead of POSS nanotechnology method.

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Activity of yFe-10Cu/H-Sep and xCu/H-Sep for the Selective Catalytic Reduction of NO with Propylene

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.518-523.281 ◽

2012 ◽

Vol 518-523 ◽

pp. 281-284

Author(s):

Qing Ye ◽

Hai Ping Wang ◽

Hai Xia Zhao ◽

Shui Yuan Cheng ◽

Tian Fang Kang

Keyword(s):

Catalytic Reduction ◽

Catalytic Performance ◽

High Dispersion ◽

High Catalytic Activity ◽

Incipient Wetness Impregnation ◽

Impregnation Method ◽

Promotional Effect ◽

Scr Of No ◽

Metal Support Interaction ◽

Metal Support

Cu supported on acid-treated sepiolite catalysts (xCu/H-Sep, x = 0  20.0 wt%) or Cu-Fe mixed supported on acid-treated sepiolite catalysts (yFe-10Cu/H-Sep, y = 0  20.0 wt%) were prepared by the incipient wetness impregnation method. The xCu/H-Sep and yFe-10Cu/H-Sep catalysts were characterized by means of XRD, BET, XRF, XPS, and H2-TPR techniques, and their catalytic activities were evaluated for the SCR of NO with propylene. XPS and XRD results indicate that there was the co-presence of Cu+-Cu2+ and Fe2+-Fe3+ over the surfaces of yFe-10Cu/H-Sep catalysts, and there was a strong interaction between Cu, Fe and sepiolite. High promotional effect of iron additive on the catalytic performance of Cu/H-Sep catalyst were found in C3H6-SCR of NO reaction. The highest activity of 65% NO conversion was obtained over 15Fe-10Cu/H-Sep catalyst at 280 oC under the condition of 1000 ppm NO, 1000 ppm C3H6, and 5% O2. The high catalytic activity of 15Fe-10Cu/H-Sep catalyst for NO reduction was due to its high reducibility to activate C3H6 to selectively reduce NO in the presence of excess O2. The high dispersion of copper oxides and strong metal-support interaction over 15Fe-10Cu/H-Sep catalyst also improve its catalytic performance.

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Nanosheet-Like Ho2O3 and Sr-Ho2O3 Catalysts for Oxidative Coupling of Methane

Catalysts ◽

10.3390/catal11030388 ◽

2021 ◽

Vol 11 (3) ◽

pp. 388

Author(s):

Yuqiao Fan ◽

Changxi Miao ◽

Yinghong Yue ◽

Weiming Hua ◽

Zi Gao

Keyword(s):

Oxidative Coupling ◽

Temperature Programmed Desorption ◽

Oxidative Coupling Of Methane ◽

Molar Ratio ◽

Impregnation Method ◽

Oxygen Species ◽

N2 Adsorption ◽

Basic Sites ◽

Chemisorbed Oxygen ◽

Temperature Programmed

In this work, Ho2O3 nanosheets were synthesized by a hydrothermal method. A series of Sr-modified Ho2O3 nanosheets (Sr-Ho2O3-NS) with a Sr/Ho molar ratio between 0.02 and 0.06 were prepared via an impregnation method. These catalysts were characterized by several techniques such as XRD, N2 adsorption, SEM, TEM, XPS, O2-TPD (temperature-programmed desorption), and CO2-TPD, and they were studied with respect to their performances in the oxidative coupling of methane (OCM). In contrast to Ho2O3 nanoparticles, Ho2O3 nanosheets display greater CH4 conversion and C2-C3 selectivity, which could be related to the preferentially exposed (222) facet on the surface of the latter catalyst. The incorporation of small amounts of Sr into Ho2O3 nanosheets leads to a higher ratio of (O− + O2−)/O2− as well as an enhanced amount of chemisorbed oxygen species and moderate basic sites, which in turn improves the OCM performance. The optimal catalytic behavior is achievable on the 0.04Sr-Ho2O3-NS catalyst with a Sr/Ho molar ratio of 0.04, which gives a 24.0% conversion of CH4 with 56.7% selectivity to C2-C3 at 650 °C. The C2-C3 yield is well correlated with the amount of moderate basic sites present on the catalysts.

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CO2 valorization into synthetic natural gas (SNG) using a Co–Ni bimetallic Y2O3 based catalysts

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2020-0163 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Radwa A. El-Salamony ◽

Sara A. El-Sharaky ◽

Seham A. Al-Temtamy ◽

Ahmed M. Al-Sabagh ◽

Hamada M. Killa

Keyword(s):

Reaction Mechanism ◽

Natural Gas ◽

Fixed Bed ◽

Catalytic Performance ◽

Fixed Bed Reactor ◽

Molar Ratio ◽

Impregnation Method ◽

Synthetic Natural Gas ◽

Methanation Reaction ◽

Co2 Valorization

Abstract Recently, because of the increasing demand for natural gas and the reduction of greenhouse gases, interests have focused on producing synthetic natural gas (SNG), which is suggested as an important future energy carrier. Hydrogenation of CO2, the so-called methanation reaction, is a suitable technique for the fixation of CO2. Nickel supported on yttrium oxide and promoted with cobalt were prepared by the wet-impregnation method respectively and characterized using SBET, XRD, FTIR, XPS, TPR, and HRTEM/EDX. CO2 hydrogenation over the Ni/Y2O3 catalyst was examined and compared with Co–Ni/Y2O3 catalysts, Co% = 10 and 15 wt/wt. The catalytic test was conducted with the use of a fixed-bed reactor under atmospheric pressure. The catalytic performance temperature was 350 °C with a supply of H2:CO2 molar ratio of 4 and a total flow rate of 200 mL/min. The CH4 yield was reached 67%, and CO2 conversion extended 48.5% with CO traces over 10Co–Ni/Y2O3 catalyst. This encourages the direct methanation reaction mechanism. However, the reaction mechanism over Ni/Y2O3 catalyst shows different behaviors rather than that over bi-metal catalysts, whereas the steam reforming of methane reaction was arisen associated with methane consumption besides increase in H2 and CO formation; at the same temperature reaction.

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Pt/UiO-66 Nanocomposites as Catalysts for CO2 Methanation Process

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2019.16607 ◽

2019 ◽

Vol 19 (6) ◽

pp. 3187-3196 ◽

Cited By ~ 5

Author(s):

Maria Mihet ◽

Gabriela Blanita ◽

Monica Dan ◽

Lucian Barbu-Tudoran ◽

Mihaela D Lazar

Keyword(s):

Thermal Stability ◽

Surface Area ◽

Metal Organic Framework ◽

Catalytic Performance ◽

Molar Ratio ◽

High Dispersion ◽

Co2 Methanation ◽

Preparation Methods ◽

Good Thermal Stability ◽

Catalytic Support

Pt/UiO-66 nanocomposites with platinum target concentration of 3 wt.% were prepared by 3 preparation methods, characterized and tested in the CO2 methanation process. Choice of the microporous UiO-66 metal-organic framework (Zr6O4(OH)4 with 1,4-benzene-dicarboxylate ligand) as catalytic support was motivated by the CO2 chemisorption capacity (proven by CO2-TPD profiles), large specific surface area (1477 m2/g) which favors a high dispersion of metal nanoparticles and good thermal stability. The preparation methods for the Pt/UiO-66 nanocomposites are: (1) wetimpregnation followed by reduction in H2 at 200 °C for 2 h; (2) wet-impregnation followed by reduction with an aqueous solution of NaBH4; and (3) “double-solvent” method, followed by reduction with NaBH4. The UiO-66 based nanocomposites were characterized by N2 adsorption–desorption (BET method), XRD, and SEM/TEM. The Pt/UiO-66 catalyst prepared by method 3 was chosen for catalytic testing due to its highest surface area, smallest platinum nanoparticles (PtNPs) size, the localization of PtNPs both on the grain’s internal and external surface and best thermal stability in the desired temperature range. Its capacity to adsorb and activate CO2 and H2 was evaluated in thermo-programmed desorption experiments (H2-TPD and CO2-TPD). Hydrogen is molecularly adsorbed, while CO2 is adsorbed both molecularly and dissociatively. The catalytic performance in the CO2 methanation process was evaluated by Temperature Programmed Reactions (TPRea, 2 °C/min, 30–350 °C), at atmospheric pressure. The best results were obtained at 350 °C, CO2:H2 molar ratio of 1:5.2 and GHSV ═ 1650 h−1. In these conditions CO2 conversion is almost 50% and CH4 selectivity is 36%, the rest of the converted CO2 being transformed in CO.

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Influence of Co2 on the Catalytic Performance Of La2O3/CeO2 and CaO/CeO2 Catalysts in the Oxidative Coupling of Methane

Polish Journal of Chemical Technology ◽

10.2478/pjct-2013-0005 ◽

2013 ◽

Vol 15 (1) ◽

pp. 22-26 ◽

Cited By ~ 5

Author(s):

Barbara Litawa ◽

Piotr Michorczyk ◽

Jan Ogonowski

Keyword(s):

Oxidative Coupling ◽

Methane Conversion ◽

Catalytic Properties ◽

Catalytic Performance ◽

Negative Influence ◽

Oxidative Coupling Of Methane ◽

Oxygen Mixture ◽

Impregnation Method ◽

Promoting Effect ◽

Conversion Of Methane

In this work the La2O3/CeO2 (33 mol % of La) and CaO/CeO2 (33 mol % of Ca) catalysts were prepared by the impregnation method and characterized by XRD and CO2-TPD. The catalytic properties of the catalysts were tested in the OCM process at 1073 K using the methane/oxygen mixture of the mole ratio 3.7 or 2.5 additionally containing CO2 and helium balance. It was found that in the presence of both catalysts an addition of CO2 enhances the selectivity to the ethylene and ethane and it does not have any negative influence on methane conversion. In the case of the CaO/CeO2 catalyst the promoting effect of CO2 was the highest. When the partial pressure of CO2 equals to 39 kPa the increase in selectivity from 36 to 41% was noted while the conversion of methane equal to 19.4-19.7 %.

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Synthesis of Dimethyl Carbonate from Ethylene Carbonate and Methanol Over Nano-Catalysts Supported on CeO2–MgO

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2015.11248 ◽

2015 ◽

Vol 15 (10) ◽

pp. 8330-8335 ◽

Cited By ~ 4

Author(s):

Jin Oh Jun ◽

Joongwon Lee ◽

Ki Hyuk Kang ◽

In Kyu Song

Keyword(s):

Dimethyl Carbonate ◽

Ethylene Carbonate ◽

Earth Metal ◽

Catalytic Performance ◽

Precipitation Method ◽

Reaction Yield ◽

Incipient Wetness Impregnation ◽

Impregnation Method ◽

Nano Catalyst ◽

Nano Catalysts

A series of CeO2(X)–MgO(1−X) (X = 0, 0.25, 0.5, 0.75, and 1.0) nano-catalysts were prepared by a co-precipitation method for use in the synthesis of dimethyl carbonate from ethylene carbonate and methanol. Among the CeO2(X)–MgO(1−X) catalysts, CeO2(0.25)–MgO(0.75) nano-catalyst showed the best catalytic performance. Alkali and alkaline earth metal oxides (MO = Li2O, K2O, Cs2O, SrO, and BaO) were then supported on CeO2(0.25)–MgO(0.75) by an incipient wetness impregnation method with an aim of improving the catalytic performance of CeO2(0.25)–MgO(0.75). Basicity of the catalysts was determined by CO2-TPD experiments in order to elucidate the effect of basicity on the catalytic performance. The correlation between catalytic performance and basicity showed that basicity played an important role in the reaction. Yield for dimethyl carbonate increased with increasing basicity of the catalysts. Among the catalysts tested, Li2O/CeO2(0.25)–MgO(0.75) nano-catalyst with the largest basicity showed the best catalytic performance in the synthesis of dimethyl carbonate.

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PROMETHEUS: A Copper-Based Polymetallic Catalyst for Automotive Applications. Part I: Synthesis and Characterization

Materials ◽

10.3390/ma14030622 ◽

2021 ◽

Vol 14 (3) ◽

pp. 622

Author(s):

Iakovos Yakoumis

Keyword(s):

Large Scale ◽

Catalytic Performance ◽

Platinum Group Metals ◽

Oxygen Storage ◽

Molar Ratio ◽

High Catalytic Activity ◽

Impregnation Method ◽

X Ray ◽

Heterogeneous Catalytic ◽

Nano Catalyst

According to the strict European exhaust emissions standards that have been imposed by European legislation there is an elevated need for the decrease of the toxic gas emissions from vehicles. Therefore, car manufacturers have implemented a series of catalytic devices in the aftertreatment of the engine to comply with the standards. All catalytic devices (such as three-way catalysts, diesel particulate filters and diesel oxidation catalysts) accumulate concentrated loading of platinum group metals (PGMs, platinum, palladium, rhodium) as the active catalytic phase. Thus, the demand for PGMs is constantly increasing with a subsequent increase in their market prices. As a result, the research on catalytic converters of high activity and reduced cost/PGM loading is of great interest. In the present work, the Prometheus catalyst, a polymetallic nanosized copper-based catalyst for automotive emission control applications, is presented in two different metal loadings (2 wt% and 5 wt%) and metal ratios (Cu/Pd/Rh = 21/7/1 and Cu/Pd/Rh = 21/7/3). For the first time, a three-metal (copper, palladium, rhodium) nano-catalyst has been synthesized and characterized on a large scale. By using copper as an active catalytic phase, a reduction of PGMs loading is achieved (up to 85%) resulting in a novel catalytic device with similar or improved catalytic performance compared to commercial ones. The Prometheus catalyst is prepared by a wet impregnation method, using as a carrier an inorganic mixed oxide (CeZrO4) exhibiting elevated oxygen storage capacity (OSC). The heterogeneous catalytic powders produced were characterized by both spectroscopic and analytical methods. The metal content and ratio were determined by inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence (XRF) and energy-dispersive X-ray spectroscopy (EDS). The morphology and the catalyst particle size were determined with scanning electron microscopy (SEM) and X-ray diffraction (XRD). The investigation revealed homogeneous particle formation and dispersion. The deposition of the metal nanoparticles on the porous inorganic carrier was verified with N2 sorption. Catalytic performance and reactivity of a catalyst (pure wash coat) with molar ratio 21/7/1 and a full-scale Prometheus catalyst with the desired loading of 15 g/ft3 were tested on an in-house synthetic gas bench (SGB) for the abatement of CO, CH4 and NO, both presenting high catalytic activity.

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Biodiesel synthesis from Pongamia Pinnata oil over modified CeO2 catalysts

Journal of the Mexican Chemical Society ◽

10.29356/jmcs.v58i4.46 ◽

2017 ◽

Vol 58 (4) ◽

Author(s):

Sathgatta Zaheeruddin Mohamed Shamshuddin ◽

Venkatesh -- ◽

Manjunatha Shyamsundar ◽

Vanagoor Thammannigowda Vasanth

Keyword(s):

Large Scale ◽

Surface Acidity ◽

Pongamia Pinnata ◽

Biodiesel Production ◽

Molar Ratio ◽

Solid Base ◽

Incipient Wetness Impregnation ◽

Impregnation Method ◽

Surface Basicity ◽

Biodiesel Synthesis

This study investigates the use of CeO2, ZrO2, MgO and CeO2-ZrO2, CeO2-MgO, CeO2-ZrO2-MgO mixed oxides as solid base catalysts for the transesterification of Pongamia Pinnata oil with methanol to produce biodiesel. SO42-/CeO2 and SO42-/CeO2-ZrO2 were also prepared and used as solid acid catalysts for esterification of Pongamia pinnata oil (P-oil) to reduce the % of free fatty acid (FFA) in P-oil. These oxide catalysts were prepared by an incipient wetness impregnation method and characterized by techniques such as NH3-TPD for surface acidity, CO2-TPD for surface basicity and powder X-ray diffraction for crystalinity. The effect of nature of the catalyst, methanol to P-oil molar ratio and reaction time in esterification as well as in transesterification was investigated. The catalytic materials were reactivated & reused for five reaction cycles and the results showed that the ceria based catalysts have reasonably good reusability both in esterification and transesterification reaction. The test results also revealed that the CeO2-ZrO2 modified with MgO could have potential for use in the large scale biodiesel production.

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PROCESS OPTIMIZATION OF BIODIESEL PRODUCTION FROM CRUDE COCONUT SEEDS OIL USING CAO/AL2O3 AS HETEROGENEOUS CATALYST

Science Proceedings Series ◽

10.31580/sps.v2i1.1266 ◽

2020 ◽

Vol 2 (1) ◽

pp. 92-97

Author(s):

Jamilu Usman ◽

Bashar Abdullahi Hadi ◽

Buhari Idris ◽

Umar Musa Tanko ◽

Bashar Usman ◽

...

Keyword(s):

Reaction Time ◽

Methyl Ester ◽

Catalyst Concentration ◽

Acid Methyl Ester ◽

Biodiesel Production ◽

Molar Ratio ◽

Incipient Wetness Impregnation ◽

Impregnation Method ◽

Promising Alternative ◽

Animal Fats

Biodiesel is an alternative diesel fuel consisting of the alkyl monoesters of fatty acids from vegetable oils or animal fats. Biodiesel is a promising alternative fuel derived from animal fats or vegetable oil through transesterification with methanol. Base catalyzed transesterification is the most commonly used technique as it is the most economical process. Presently, a lot of heterogeneous catalysts have been formulated that are more effective than the homogeneous catalysts. CaO/Al2O3 was synthesized using incipient wetness impregnation method. The biodiesel was developed and optimized using Box-behnken response surface methodology (RSM) design provided using MINITAP-17 statistical software. The four independent variables considered are: reaction time, methanol to oil ratio, reaction temperature and catalyst concentration. The response chosen was fatty acid methyl ester (FAME) yields which were obtained from the reaction. The result from analysis of variance (ANOVA) showed a satisfactory result. Moreover, the input variables showed greater significance on the response which are reaction time and temperature base on F and P-value. The statistical models developed for predicting biodiesel yield revealed a significant agreement between the experimental and predicted values (R = 0.9686). An optimum methyl ester yield of 93.29 % was achieved with optimal conditions of methanol/oil molar ratio of 6:1, temperature of 600C, reaction time of 120 min and catalyst concentration of 1.0 wt%. The properties of the biodiesel produced also falls within the range prescribed by ASTM standard

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Preparation of bimetallic Ni–Fe/MCM-41 catalysts and their catalytic activity for CO methanation

Progress in Reaction Kinetics and Mechanism ◽

10.1177/1468678319870327 ◽

2019 ◽

Vol 45 ◽

pp. 146867831987032

Author(s):

Zhang Jiaying

Keyword(s):

Bimetallic Catalysts ◽

Space Velocity ◽

Molar Ratio ◽

Incipient Wetness Impregnation ◽

Impregnation Method ◽

Activity Increase ◽

Co Methanation ◽

Weight Hourly Space Velocity ◽

Temperature Programmed ◽

Mcm 41

A series of Ni–Fe/MCM-41 bimetallic catalysts and also Ni/MCM-41 and Fe/MCM-41 catalysts were prepared by the incipient-wetness impregnation method and tested for their activity for CO methanation in a continuous-flow microreactor. The results showed that the catalytic activities of the Ni–Fe/MCM-41 bimetallic catalysts were much higher than those of the Ni/MCM-41 and Fe/MCM-41 catalysts at low temperatures (200°C–325°C). The 10%Ni–5%Fe/MCM-41 catalyst showed the best activity with a CO conversion of almost 100% and a CH4 selectivity of 98% at 350°C under a pressure of 1.5 MPa with a 3:1 molar ratio of H2 to CO and a weight hourly space velocity of 12,000 mL h−1 g−1. The catalysts were characterized by N2 physisorption measurements, X-ray diffraction, and H2-temperature-programmed reduction. The results showed that the addition of Fe will lead to the formation of finer Ni particles and Ni–Fe alloy, which were the main reasons for the activity increase in the Ni–Fe/MCM-41 catalysts.

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