Rapid Aging as a Key to Understand Deactivation of Ni/Al2O3 Catalysts Applied for the CO2 Methanation

Abstract We developed a rapid aging method for Ni/Al2O3 methanation catalysts mimicking the real aging in the actual application. The method is based on hydrothermal deactivation of the catalyst at 600 or 700 °C, which leads to a catalyst with nearly constant conversion after a much shorter time period compared to normal aging. The hydrothermally aged catalysts are characterized by N2 adsorption, X-ray powder diffraction, temperature-programmed reduction and H2 chemisorption. The catalytic performance of the aged catalysts is comparable to the one of a catalyst deactivated in a long-term measurement with up to 720 h on stream. The time needed for reaching a stable conversion can be diminished by rapid aging by a factor of 10. The investigations also showed that the long-term deactivation is caused by Ni particle sintering and that the support pores limit the Ni particle size. Graphical Abstract

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Preparation and Characterization of Ni-Modified Fe-Mo and Catalytic Selective Oxidation of p-Xylene

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.557-559.1501 ◽

2012 ◽

Vol 557-559 ◽

pp. 1501-1504 ◽

Cited By ~ 2

Author(s):

Zu Zeng Qin ◽

Zi Li Liu ◽

Yan Bin Liu ◽

Rui Wen Liu

Keyword(s):

Photoelectron Spectrum ◽

Sol Gel ◽

Catalytic Performance ◽

Ni Catalyst ◽

Temperature Programmed Reduction ◽

X Ray ◽

Mo Catalyst ◽

Ft Ir ◽

Temperature Programmed

The preparation of the Fe-Mo-Ni catalyst using the sol-gel method was investigated. In addition, the catalytic selective oxidations of p-xylene (PX) to terephthalaldehyde (TPAL) on the Fe-Mo-Ni catalyst were also investigated. The catalysts were characterized using thermal analysis, H2-temperature programmed reduction (H2-TPR), Fourier transform infrared spectra (FT-IR), and X-ray photoelectron spectrum (XPS). The additional of Ni improves the catalytic activity of the Fe-Mo catalyst on selective oxidations of PX to TPAL. The optimal additive amount of Ni is 5%. XPS analysis shows that the introduction of Ni changes the internal structure of the Fe-Mo catalyst improves catalytic performance.

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The Reduction Properties of Hexa Aluminates Substituted by Different Metal Ions for Denitrification System

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.734-737.2364 ◽

2013 ◽

Vol 734-737 ◽

pp. 2364-2368

Author(s):

Xiao Guang Ren ◽

Fu Xia Li ◽

Peng Li ◽

Wei Hou

Keyword(s):

Metal Ions ◽

Surface Area ◽

Catalytic Performance ◽

Precipitation Method ◽

Temperature Programmed Reduction ◽

X Ray Diffraction ◽

X Ray ◽

Temperature Programmed ◽

Co Precipitation

In this study, the hexaaluminate catalyst SrMnMAl10O19-δ（M= Cd、Co、Cu 、Fe、Ni、Zn、Zr、Cr and Y）and SrMnFexAl11-xO19-δ(x=1, 2, 4, 6, 8)have been prepared by co-precipitation method. The catalysts were characterized by powder X-ray diffraction (XRD), surface area (BET), hydrogen temperature programmed reduction (H2-TPR). The reduction catalyst properties of hexaaluminate for deNOx were evaluated by using devices of micro-evaluation. The results showed that the CO could remove NOx very well. The hexaaluminate not only have a good catalytic performance, but also can form a complete crystal calcined at 1200 °C for 4 h.

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Novel Nickel- and Magnesium-Modified Cenospheres as Catalysts for Dry Reforming of Methane at Moderate Temperatures

Catalysts ◽

10.3390/catal9121066 ◽

2019 ◽

Vol 9 (12) ◽

pp. 1066 ◽

Cited By ~ 2

Author(s):

Bogdan Samojeden ◽

Marta Kamienowska ◽

Armando Izquierdo Colorado ◽

Maria Elena Galvez ◽

Ilona Kolebuk ◽

...

Keyword(s):

Supported Catalysts ◽

Temperature Programmed Desorption ◽

Catalytic Performance ◽

Dry Reforming ◽

Dry Reforming Of Methane ◽

Temperature Programmed Reduction ◽

Fly Ashes ◽

Coal Fly Ashes ◽

Temperature Programmed ◽

Mg Content

Cenospheres from coal fly ashes were used as support in the preparation of Ni–Mg catalysts for dry reforming of methane. These materials were characterized by means of XRD, H2-temperature-programmed reduction (H2-TPR), CO2-temperature-programmed desorption (CO2-TPD), and low-temperature nitrogen sorption techniques. The cenosphere-supported catalysts showed relatively high activity and good stability in the dry reforming of methane (DRM) at 700 °C. The catalytic performance of modified cenospheres was found to depend on both Ni and Mg content. The highest activity at 750 °C and 1 atm was observed for the catalyst containing 30 wt % Mg and 10, 20, and 30 wt % Ni, yielding to CO2 and CH4 conversions of around 95%.

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The Effect of Mg and Zn Dopants on Pt/Al2O3 for the Dehydrogenation of Perhydrodibenzyltoluene

Catalysts ◽

10.3390/catal11040490 ◽

2021 ◽

Vol 11 (4) ◽

pp. 490

Author(s):

Rudaviro Garidzirai ◽

Phillimon Modisha ◽

Innocent Shuro ◽

Jacobus Visagie ◽

Pieter van Helden ◽

...

Keyword(s):

Electron Microscopy ◽

Inductively Coupled Plasma ◽

Flow Reactor ◽

Plug Flow ◽

Optical Emission ◽

Catalytic Performance ◽

Emission Spectrometry ◽

Hydrogen Yield ◽

X Ray ◽

Temperature Programmed

The effects of Mg and Zn dopants on the catalytic performance of Pt/Al2O3 catalyst were investigated for dehydrogenation of perhydrodibenzyltoluene (H18-DBT) as a liquid organic hydrogen carrier. Al2O3 supports were modified with Mg and Zn to produce Mg-Al2O3 and Zn-Al2O3 with a target loading of 3.8 wt.% for dopants. The modified supports were impregnated with chloroplatinic acid solution to produce the catalysts Pt/Al2O3, Pt/Mg-Al2O3 and Pt/Zn-Al2O3 of 0.5 wt.% Pt loading. Thereafter, the catalysts were characterised using inductively coupled plasma- optical emission spectrometry, scanning electron microscopy-energy dispersive X-ray spectroscopy, hydrogen temperature-programmed reduction, carbon-monoxide pulse chemisorption, ammonia temperature-programmed desorption, X-ray diffraction and transmission electron microscopy. The dehydrogenation experiments were performed using a horizontal plug flow reactor system and the catalyst time-on-stream was 22 h. Pt/Mg-Al2O3 showed the highest average hydrogen flowrate of 29 nL/h, while an average of 27 nL/h was obtained for both Pt/Al2O3 and Pt/Zn-Al2O3. This has resulted in a hydrogen yield of 80% for Pt/Mg-Al2O3, 71% for Pt/Zn-Al2O3 and 73% for Pt/Al2O3. In addition, the conversion of H18-DBT ranges from 99% to 92%, Pt 97–90% and 96–90% for Pt/Mg-Al2O3, Pt/Zn-Al2O3 and Pt/Al2O3, respectively. Following the latter catalyst order, the selectivity to dibenzyltoluene (H0-DBT) ranges from 78% to 57%, 75–51% and 71–45%. Therefore, Pt/Mg-Al2O3 showed improved catalytic performance towards dehydrogenation of H18-DBT.

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Influence of Sulfur-Containing Sodium Salt Poisoned V2O5–WO3/TiO2 Catalysts on SO2–SO3 Conversion and NO Removal

Catalysts ◽

10.3390/catal8110541 ◽

2018 ◽

Vol 8 (11) ◽

pp. 541 ◽

Cited By ~ 3

Author(s):

Haiping Xiao ◽

Chaozong Dou ◽

Hao Shi ◽

Jinlin Ge ◽

Li Cai

Keyword(s):

Photoelectron Spectroscopy ◽

No Reduction ◽

Catalytic Performance ◽

Acid Sites ◽

Impregnation Method ◽

So2 Oxidation ◽

Sodium Salts ◽

X Ray ◽

Temperature Programmed ◽

Physical Features

A series of poisoned catalysts with various forms and contents of sodium salts (Na2SO4 and Na2S2O7) were prepared using the wet impregnation method. The influence of sodium salts poisoned catalysts on SO2 oxidation and NO reduction was investigated. The chemical and physical features of the catalysts were characterized via NH3-temperature programmed desorption (NH3-TPD), H2-temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FT-IR). The results showed that sodium salts poisoned catalysts led to a decrease in the denitration efficiency. The 3.6% Na2SO4 poisoned catalyst was the most severely deactivated with denitration efficiency of only 50.97% at 350 °C. The introduction of SO42− and S2O72− created new Brønsted acid sites, which facilitated the adsorption of NH3 and NO reduction. The sodium salts poisoned catalysts significantly increased the conversion of SO2–SO3. 3.6%Na2S2O7 poisoned catalyst had the strongest effect on SO2 oxidation and the catalyst achieved a maximum SO2–SO3-conversion of 1.44% at 410 °C. Characterization results showed sodium salts poisoned catalysts consumed the active ingredient and lowered the V4+/V5+ ratio, which suppressed catalytic performance. However, they increased the content of chemically adsorbed oxygen and the strength of V5+=O bonds, which promoted SO2 oxidation.

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Catalytic Abatement of Volatile Organic Compounds and Soot over Manganese Oxide Catalysts

Materials ◽

10.3390/ma14164534 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4534

Author(s):

Miguel Jose Marin Figueredo ◽

Clarissa Cocuzza ◽

Samir Bensaid ◽

Debora Fino ◽

Marco Piumetti ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Low Temperature ◽

Manganese Oxide ◽

Organic Compounds ◽

Catalytic Performance ◽

Oxide Catalysts ◽

X Ray ◽

Manganese Oxide Catalysts ◽

Volatile Organic ◽

Temperature Programmed

A set of manganese oxide catalysts was synthesized via two preparation techniques: solution combustion synthesis (Mn3O4/Mn2O3-SCS and Mn2O3-SCS) and sol-gel synthesis (Mn2O3-SG550 and Mn2O3-SG650). The physicochemical properties of the catalysts were studied by means of N2-physisorption at −196 °C, X-ray powder diffraction, H2 temperature-programmed reduction (H2-TPR), soot-TPR, X-ray photoelectron spectroscopy (XPS) and field-emission scanning electron microscopy (FESEM). The high catalytic performance of the catalysts was verified in the oxidation of Volatile Organic Compounds (VOC) probe molecules (ethene and propene) and carbon soot in a temperature-programmed oxidation setup. The best catalytic performances in soot abatement were observed for the Mn2O3-SG550 and the Mn3O4/Mn2O3-SCS catalysts. The catalytic activity in VOC total oxidation was effectively correlated to the enhanced low-temperature reducibility of the catalysts and the abundant surface Oα-species. Likewise, low-temperature oxidation of soot in tight contact occurred over the Mn2O3-SG550 catalyst and was attributed to high amounts of surface Oα-species and better surface reducibility. For the soot oxidation in loose contact, the improved catalytic performance of the Mn3O4/Mn2O3-SCS catalyst was attributed to the beneficial effects of both the morphological structure that—like a filter—enhanced the capture of soot particles and to a probable high amount of surface acid-sites, which is characteristic of Mn3O4 catalysts.

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Existence and Exploitability of Financial Analysts' Informational Leadership

Applied Finance Letters ◽

10.24135/afl.v5i2.49 ◽

2016 ◽

Vol 5 (2) ◽

Author(s):

Rainer Baule ◽

Hannes Wilke

Keyword(s):

Abnormal Returns ◽

Relevant Information ◽

Trading Strategies ◽

Information Share ◽

Time Period ◽

The Us ◽

Information Shares ◽

Set Up ◽

The One

This paper bridges two recent studies on the role of analysts to provide new and relevant information to investors. On the one hand, the contribution of analysts to long-term price discovery on the US market is rather low. Considering earnings per share forecasts as the main output of analysts’ reports, their information share amounts to only 4.6% on average. On the other hand, trading strategies set up on these EPS forecasts are quite profitable. Self-financing portfolios yield excess returns of more than 5% over the S&P 100 index for a time period of 36 years, which is persistent after controlling for the well-known risk factors. In this paper, we discuss the link between the low information shares and the high abnormal returns. We argue that information shares of analysts cannot be higher, because otherwise their forecasts would lead to excessively profitable trading strategies which are very unlikely to persist over such a long period of time.

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Precipitated K-Promoted Co–Mn–Al Mixed Oxides for Direct NO Decomposition: Preparation and Properties

Catalysts ◽

10.3390/catal9070592 ◽

2019 ◽

Vol 9 (7) ◽

pp. 592 ◽

Cited By ~ 3

Author(s):

Květa Jirátová ◽

Kateřina Pacultová ◽

Jana Balabánová ◽

Kateřina Karásková ◽

Anna Klegová ◽

...

Keyword(s):

Catalytic Activity ◽

Mixed Oxides ◽

No Decomposition ◽

Temperature Programmed Reduction ◽

X Ray ◽

Co2 Desorption ◽

Metal Nitrates ◽

Temperature Programmed ◽

Desorption Method ◽

Al Oxide

Direct decomposition of nitric oxide (NO) proceeds over Co–Mn–Al mixed oxides promoted by potassium. In this study, answers to the following questions have been searched: Do the properties of the K-promoted Co–Mn–Al catalysts prepared by different methods differ from each other? The K-precipitated Co–Mn–Al oxide catalysts were prepared by the precipitation of metal nitrates with a solution of K2CO3/KOH, followed by the washing of the precipitate to different degrees of residual K amounts, and by cthe alcination of the precursors at 500 °C. The properties of the prepared catalysts were compared with those of the best catalyst prepared by the K-impregnation of a wet cake of Co–Mn–Al oxide precursors. The solids were characterized by chemical analysis, DTG, XRD, N2 physisorption, FTIR, temperature programmed reduction (H2-TPR), temperature programmed CO2 desorption (CO2-TPD), X-ray photoelectron spectrometry (XPS), and the species-resolved thermal alkali desorption method (SR-TAD). The washing of the K-precipitated cake resulted in decreasing the K amount in the solid, which affected the basicity, reducibility, and non-linearly catalytic activity in NO decomposition. The highest activity was found at ca 8 wt.% of K, while that of the best K-impregnated wet cake catalyst was at about 2 wt.% of K. The optimization of the cake washing conditions led to a higher catalytic activity.

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Generalized Methodology for Inserting Metal Heteroatoms into the Layered Zeolite Precursor RUB-36 by Interlayer Expansion

Crystals ◽

10.3390/cryst10060530 ◽

2020 ◽

Vol 10 (6) ◽

pp. 530 ◽

Cited By ~ 2

Author(s):

Chaoqun Bian ◽

Xiao Wang ◽

Lan Yu ◽

Fen Zhang ◽

Jie Zhang ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Inductively Coupled Plasma ◽

Catalytic Performance ◽

X Ray Diffraction ◽

Zeolite Sample ◽

X Ray ◽

Inductively Coupled ◽

Temperature Programmed ◽

First Time ◽

N2 Sorption

The incorporation of metal heteroatoms into zeolites is an effective modification strategy for enhancing their catalytic performance. Herein, for the first time we report a generalized methodology for inserting metal heteroatoms (such as Sn, Fe, Zn, and Co) into the layered zeolite precursor RUB-36 via interlayer expansion by using the corresponding metal acetylacetate salt. Through this generalized methodology, Sn-JHP-1, Fe-JHP-1, Zn-JHP-1 and Co-JHP-1 zeolites could be successfully prepared by the reaction of RUB-36 and corresponding metal acetylacetate salt at 180 °C for 24 h in the presence of HCl solution. As a typical example, Sn-JHP-1 and calcined Sn-JHP-1 (Sn-JHP-2) zeolite is well characterized by the X-ray diffraction (XRD), diffuse reflectance ultraviolet-visible (UV-Vis), inductively coupled plasma (ICP), N2 sorption, temperature-programmed-desorption of ammonia (NH3-TPD) and X-ray photoelectron spectroscopy (XPS) techniques, which confirm the expansion of adjacent interlayers and thus the incorporation of isolated Sn sites within the zeolite structure. Notably, the obtained Sn-JHP-2 zeolite sample shows enhanced catalytic performance in the conversion of glucose to levulinic acid (LA) reaction.

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CO2 Methanation over Ni/Al@MAl2O4 (M = Zn, Mg, or Mn) Catalysts

Catalysts ◽

10.3390/catal9070599 ◽

2019 ◽

Vol 9 (7) ◽

pp. 599 ◽

Cited By ~ 9

Author(s):

Le ◽

Kim ◽

Jeong ◽

Park

Keyword(s):

Surface Oxidation ◽

Catalytic Performance ◽

Precipitation Method ◽

Core Shell ◽

Ni Doping ◽

Ni Catalysts ◽

Co2 Methanation ◽

Temperature Programmed ◽

Diffuse Reflectance Infrared ◽

Spinel Structures

In this study, unique core-shell aluminate spinel supports, Al@MAl2O4 (M = Zn, Mg, or Mn), were obtained by simple hydrothermal surface oxidation and were applied to the preparation of supported Ni catalysts for CO2 methanation. For comparison, CO methanation was also evaluated using the same catalysts. The prepared catalysts were characterized with a variety of techniques, including N2 physisorption, CO2 chemisorption, H2 chemisorption, temperature-programmed reduction with H2, temperature-programmed desorption of CO2, X-ray diffraction, high-resolution transmission electron microscopy, and in-situ diffuse reflectance infrared Fourier transform spectroscopy. The combination of supports with core-shell spinel structures and Ni doping with a deposition–precipitation method created outstanding catalytic performance of the Ni catalysts supported on Al@MgAl2O4 and Al@MnAl2O4 due to improved dispersion of Ni nanoparticles and creation of moderate basic sites with suitable strength. Good stability of Ni/Al@MnAl2O4 catalyst was also confirmed in the study.

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