scholarly journals Modern Trends in Design of Catalysts for Transformation of Biofuels into Syngas and Hydrogen: From Fundamental Bases to Performance in Real Feeds

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6334
Author(s):  
Vladislav Sadykov ◽  
Mikhail Simonov ◽  
Nikita Eremeev ◽  
Natalia Mezentseva
Keyword(s):  
Natural Gas ◽  
High Surface ◽  
High Surface Area ◽  
Internal Heat ◽  
Pilot Scale ◽  
Platinum Group Metals ◽  
Atomic Scale ◽  
Active Components ◽  
Structured Catalysts ◽  
Metal Support Interaction

This review considers problems related to design of efficient structured catalysts for natural gas and biofuels transformation into syngas. Their active components are comprised of fluorite, perovskite and spinel oxides or their nanocomposites (both bulk and supported on high surface area Mg-doped alumina or MgAl2O4) promoted by platinum group metals, nickel and their alloys. A complex of modern structural, spectroscopic and kinetic methods was applied to elucidate atomic-scale factors controlling their performance and stability to coking, such as dispersion of metals/alloys, strong metal-support interaction and oxygen mobility/reactivity as dependent upon their composition and synthesis procedures. Monolithic catalysts comprised of optimized active components loaded on structured substrates with a high thermal conductivity demonstrated high activity and stability to coking in processes of natural gas and biofuels reforming into syngas. A pilot-scale axial reactor equipped with the internal heat exchanger and such catalysts allowed to efficiently convert into syngas the mixture of natural gas, air and liquid biofuels in the autothermal reforming mode at low (~50–100 °C) inlet temperatures and GHSV up to 40,000 h−1.

Electron holography of catalysts

1995 ◽  
Vol 53 ◽  
pp. 416-417
Author(s):  
A. K. Datye ◽  
D. S. Kalakkad ◽  
L. F. Allard ◽  
E. Völkl
Keyword(s):  
Heterogeneous Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Atomic Scale ◽  
Nano Particles ◽  
Phase Image ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Phase Information ◽  
Particle Structure

The active phase in heterogeneous catalysts consists of nanometer-sized metal or oxide particles dispersed within the tortuous pore structure of a high surface area matrix. Such catalysts are extensively used for controlling emissions from automobile exhausts or in industrial processes such as the refining of crude oil to produce gasoline. The morphology of these nano-particles is of great interest to catalytic chemists since it affects the activity and selectivity for a class of reactions known as structure-sensitive reactions. In this paper, we describe some of the challenges in the study of heterogeneous catalysts, and provide examples of how electron holography can help in extracting details of particle structure and morphology on an atomic scale.Conventional high-resolution TEM imaging methods permit the image intensity to be recorded, but the phase information in the complex image wave is lost. However, it is the phase information which is sensitive at the atomic scale to changes in specimen thickness and composition, and thus analysis of the phase image can yield important information on morphological details at the nanometer level.

Pilot Scale Testing of a New Radium-226 Removal Process

1985 ◽  
Vol 20 (2) ◽  
pp. 55-67
Author(s):  
W.B. Anderson ◽  
P.M. Huck ◽  
T.M.R. Meadley ◽  
T.P. Hynes
Keyword(s):  
Treatment Process ◽  
No Reduction ◽  
High Surface ◽  
High Surface Area ◽  
Barium Chloride ◽  
Pilot Scale ◽  
Activity Levels ◽  
New Process ◽  
Removal Efficiencies ◽  
New Treatment

Abstract This paper describes the on-going pilot scale development of a new treatment process designed to remove radium-226 from uranium milling effluents. Presently, decants from Canadian uranium mining and milling tailings areas are treated with barium chloride to remove radium-226 prior to discharge into the environment. This is usually accomplished in large natural or man-made ponds which provide an opportunity for a (Ba,Ra)SO4 precipitate to form and subsequently settle. Sand filtration is sometimes used as a polishing step. This new process differs from conventional and other experimental processes in that it involves the use of a fluidized bed to facilitate the deposition of a (Ba,Ra)SO4 precipitate on a granular medium of high surface area. As a stand-alone treatment process, the new process is consistently able to reduce incoming radium-226 activity levels by 90-99%. Effluent levels of 10 pCi/L (0.370 Bq/L) or less have been achieved, depending on the influent activity levels. Recent testing of the process as a polishing step has demonstrated radium removal efficiencies up to 60% when the process influent was already less than 5 pCi/L (0.185 Bq/L). The process has been operated at temperatures ranging from 26°C down to 0.3°C with no reduction in efficiency. In contrast to treatment times in the order of days for conventional settling pond systems and hours for mechanical stirred tank/filtration systems, the new process is able to achieve these radium removal efficiencies in times on the order of one minute.

Studies of Supported Metal Catalysts Using Low Voltage Biased Secondary Electron Imaging in a JSM-6320f Fe-SEM

1997 ◽  
Vol 3 (S2) ◽  
pp. 1223-1224
Author(s):  
J. Liu ◽  
R. L. Ornberg ◽  
J. R. Ebner
Keyword(s):  
Secondary Electron ◽  
Low Voltage ◽  
Supported Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Incident Beam ◽  
Active Species ◽  
Supported Metal Catalysts ◽  
Active Components ◽  
Electron Imaging

Many industrial catalysts have a complex geometric structure to enable reacting gases or fluids to reach as much of the active surface of the catalyst as possible. The catalyzing surface frequently consists of a complex chemical mixture of different phases produced by an evolved chemical process. The active components are often very small particles dispersed on high-surface-area supports. The catalytic properties of this type of catalyst depend on the structure, composition, and morphology of the active species as well as the supports. TEM/STEM and associated techniques have been used extensively to characterize the structure and composition of supported catalysts. Surface morphology of supported catalysts is generally examined by secondary electron imaging, especially at low incident beam energies. It is, however, frequently found that small metal particles are not usually seen in SE images because of the complication of support topography

IGR Solid-State Electrochemical NOx Control for Natural Gas Combustion Exhaust Gases

1989 ◽  
Vol 111 (3) ◽  
pp. 394-397 ◽  
Author(s):  
M. S. Hossain ◽  
M. Neyman ◽  
W. J. Cook ◽  
A. Z. Gordon
Keyword(s):  
Solid State ◽  
Natural Gas ◽  
High Surface ◽  
Nox Reduction ◽  
High Surface Area ◽  
Combustion Products ◽  
Gas Combustion ◽  
Electrochemical Technology ◽  
Natural Gas Combustion ◽  
Nox Control

Solid-state electrochemical technology, embodied in the IGR process, is used to reduce nitrogen oxides (NOx) to nitrogen and oxygen, and thereby control NOx emissions from natural gas powered engines. The IGR deNOx process is based on solid-state, flow-through, high surface area, porous oxygen ion conductive ceramic electrolytes. Recent bench-scale experiments conducted for the Gas Research Institute have demonstrated NOx reduction in multicomponent gas streams, the inert portion of which simulate natural gas combustion products. The reduction products were analyzed by in situ gas chromatography to verify NOx reduction rates inferred from electrochemical measurements. IGR process advantages compared with existing NOx control technologies are reviewed.

scholarly journals Pilot-Scale Assessment of a Novel Farrowing Creep Area Supplementary Heat Source

Animals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 996
Author(s):  
Benjamin C. Smith ◽  
Brett C. Ramirez ◽  
Steven J. Hoff ◽  
Laura L. Greiner
Keyword(s):  
Heat Source ◽  
High Surface ◽  
Average Daily Gain ◽  
High Surface Area ◽  
Weight Ratio ◽  
Pilot Scale ◽  
Swine Industry ◽  
Productivity Losses ◽  
Significant Difference ◽  
The Us

Pre-weaning morality (PWM) is attributed to a poor creep area microclimate and causes major economic and productivity losses for the US swine industry. Piglets need supplementary heat to overcome a high surface area to body weight ratio and minimal thermoregulation. A pilot-scale study was conducted to evaluate a semi-enclosed heated microclimate (SEHM) as a supplementary heat source for farrowing creep areas over six farrowing cycles (from January to July 2019) in two rooms with 24 farrowing stalls in each room. Six SEHMs (each SEHM covers two stalls) were randomly distributed to each room and compared to heat lamps (HLs) for productivity and electricity usage. Data from 113 (SEHM) and 101 litters (HL) showed no significant difference between treatments in average daily gain (p = 0.26), 252.4 ± 8.0 g hd−1 d−1 (SEHM) and 260.3 ± 8.1 g hd−1 d−1 (HL) and PWM (p = 0.08), 9.67% ± 0.82% (SEHM) and 12.04% ± 0.87% (HL). However, a significant difference (p = 0.02) was noted in the PWM attributed to over-lay mortalities, 4.05% ± 0.76% (SEHM) compared to 6.04% ± 0.78% (HL). The SEHM electricity averaged 3.25 kWh d−1 (2.91, 3.59 kWh d−1; 95% CI), which was significantly different (p < 0.01) from the HL equivalent (125 W bulb; 6 kWh d−1).

scholarly journals Nanotubular Titanium Oxynitride with an Ultra-Low Iridium Loading as a High-Performance Oxygen-Evolution-Reaction Thin-Film Electrode

2020 ◽  
Author(s):  
Marjan Bele ◽  
Primož Jovanovič ◽  
Živa Marinko ◽  
Sandra Drev ◽  
Vid Simon Šelih ◽  
...  
Keyword(s):  
Thin Film ◽  
Oxygen Evolution ◽  
Photoelectron Spectroscopy ◽  
Oxygen Evolution Reaction ◽  
High Performance ◽  
High Surface ◽  
High Surface Area ◽  
Additional Contribution ◽  
X Ray ◽  
Metal Support Interaction

The present study targets one of the grand challenges of electrochemical hydrogen production: a durable and cost-effective oxygen-evolution catalyst. We present a thin-film composite electrode with a unique morphology and an ultra-low loading of iridium that has extraordinary electrocatalytic properties. This is accomplished by the electrochemical growth of a defined, high-surface-area titanium oxide nanotubular film followed by the nitridation and effective immobilization of iridium nanoparticles. The applicative relevance of this production process is justified by a remarkable oxygen-evolution reaction (OER) activity and high stability. Due to the confinement inside the pores and the strong metal-support interaction (SMSI) effects, the OER exhibited a higher turnover. The high durability is achieved by self-passivation of the titanium oxynitride (TiON) surface layer with TiO<sub>2</sub>, which in addition also effectively embeds the Ir nanoparticles, while still keeping them electrically wired. An additional contribution to the enhanced durability comes from the nitrogen atoms, which according to our DFT calculations reduce the tendency of the Ir nanoparticles to grow. We also introduce an advanced electrochemical characterization platform for the in-depth study of thin-film electrodes. Namely, the entire process of the TiON-Ir electrode’s preparation and the electrochemical evaluation can be tracked with scanning electron microscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) at identical locations. In general, the novel experimental approach allows for the unique morphological, structural and compositional insights into the preparation and electrocatalytic performance of thin films, making it useful also outside electrocatalysis applications.

scholarly journals Titanium Dioxide as a Catalyst Support in Heterogeneous Catalysis

2014 ◽  
Vol 2014 ◽  
pp. 1-21 ◽  
Author(s):  
Samira Bagheri ◽  
Nurhidayatullaili Muhd Julkapli ◽  
Sharifah Bee Abd Hamid
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
High Surface ◽  
Catalyst Support ◽  
High Surface Area ◽  
Supported Metal Catalysts ◽  
Support Material ◽  
Oxidation Reactions ◽  
Base Property ◽  
Metal Support Interaction

The lack of stability is a challenge for most heterogeneous catalysts. During operations, the agglomeration of particles may block the active sites of the catalyst, which is believed to contribute to its instability. Recently, titanium oxide (TiO2) was introduced as an alternative support material for heterogeneous catalyst due to the effect of its high surface area stabilizing the catalysts in its mesoporous structure. TiO2supported metal catalysts have attracted interest due to TiO2nanoparticles high activity for various reduction and oxidation reactions at low pressures and temperatures. Furthermore, TiO2was found to be a good metal oxide catalyst support due to the strong metal support interaction, chemical stability, and acid-base property. The aforementioned properties make heterogeneous TiO2supported catalysts show a high potential in photocatalyst-related applications, electrodes for wet solar cells, synthesis of fine chemicals, and others. This review focuses on TiO2as a support material for heterogeneous catalysts and its potential applications.

Nanotubular Titanium Oxynitride with an Ultra-Low Iridium Loading as a High-Performance Oxygen-Evolution-Reaction Thin-Film Electrode

2020 ◽  
Author(s):  
Marjan Bele ◽  
Primož Jovanovič ◽  
Živa Marinko ◽  
Sandra Drev ◽  
Vid Simon Šelih ◽  
...  
Keyword(s):  
Thin Film ◽  
Oxygen Evolution ◽  
Photoelectron Spectroscopy ◽  
Oxygen Evolution Reaction ◽  
High Performance ◽  
High Surface ◽  
High Surface Area ◽  
Additional Contribution ◽  
X Ray ◽  
Metal Support Interaction

The present study targets one of the grand challenges of electrochemical hydrogen production: a durable and cost-effective oxygen-evolution catalyst. We present a thin-film composite electrode with a unique morphology and an ultra-low loading of iridium that has extraordinary electrocatalytic properties. This is accomplished by the electrochemical growth of a defined, high-surface-area titanium oxide nanotubular film followed by the nitridation and effective immobilization of iridium nanoparticles. The applicative relevance of this production process is justified by a remarkable oxygen-evolution reaction (OER) activity and high stability. Due to the confinement inside the pores and the strong metal-support interaction (SMSI) effects, the OER exhibited a higher turnover. The high durability is achieved by self-passivation of the titanium oxynitride (TiON) surface layer with TiO<sub>2</sub>, which in addition also effectively embeds the Ir nanoparticles, while still keeping them electrically wired. An additional contribution to the enhanced durability comes from the nitrogen atoms, which according to our DFT calculations reduce the tendency of the Ir nanoparticles to grow. We also introduce an advanced electrochemical characterization platform for the in-depth study of thin-film electrodes. Namely, the entire process of the TiON-Ir electrode’s preparation and the electrochemical evaluation can be tracked with scanning electron microscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) at identical locations. In general, the novel experimental approach allows for the unique morphological, structural and compositional insights into the preparation and electrocatalytic performance of thin films, making it useful also outside electrocatalysis applications.

scholarly journals Morphological evolution of Pt-modified nanoporous gold after thermal coarsening in reductive and oxidative environments

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
A. A. El-Zoka ◽  
B. Langelier ◽  
G. A. Botton ◽  
R. C. Newman
Keyword(s):  
Surface Area ◽  
Morphological Evolution ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Atom Probe ◽  
Nanoporous Gold ◽  
Atomic Scale ◽  
Thermal Coarsening

AbstractNanoporous gold made by dealloying AgAuPt (NPG-Pt) has been shown to exhibit several interesting catalytic properties, tied to its exceptionally high surface area; however, structural degradation may occur owing to thermal coarsening. To understand the effect of atmosphere chemistry on thermal coarsening and degradation, and means of limiting it, this study focuses on the high-resolution characterization of NPG-Pt layers coarsened in reductive Ar-H2 atmosphere, and in oxidative air. Atom probe tomography (APT) analysis is performed on NPG-Pt, coarsened separately in either Ar-H2 or air, to characterize the atomic-scale chemical changes in the nanoligaments and to develop a mechanistic view of the inherent processes. A tendency of Ag to segregate to the surface during coarsening is found to lead to complete elimination of the nanoligament core-shell structures in both cases. Large Pt segregates form during coarsening in Ar-H2, but under the surface of the ligaments, having relatively little effect on the coarsening rate. The oxygen-induced segregation of Pt was observed to cause the inhibition of thermal coarsening after minor loss in surface area-to-volume ratio. Findings in this paper help in understanding further the thermal coarsening of heterogeneous nanomaterials made by dealloying, and the pertinent factors that come into play in different chemical environments.

Nanocrystalline Doped Cerium Oxide as a Catalyst for SO2 Reduction by Co

1994 ◽  
Vol 344 ◽  
Author(s):  
Andreas Tschöpe ◽  
J. Y. Ying ◽  
W. Liu ◽  
M. Flytzani-Stephanopoulos
Keyword(s):  
Oxygen Vacancies ◽  
Elemental Sulfur ◽  
High Surface ◽  
High Surface Area ◽  
High Catalytic Activity ◽  
Metal Target ◽  
High Concentration ◽  
Gas Condensation ◽  
Structured Catalysts ◽  
La Doped

AbstractNanocrystalline processing by inert gas condensation has the inherent advantages of generating: (1) high surface area nanoclusters, (2) non-stoichiometric oxides, and (3) high dispersions of dopants. This approach is exploited in the synthesis of fluorite-structured catalysts for SO2 reduction by CO. Nanocrystalline CeO2-x, La-doped CeO2-x, and Cu-doped CeO2-x were produced by magnetron sputtering from a pure or mixed metal target, followed by controlled oxidation of the metallic clusters. The as-prepared doped and undoped nanocrystalline CeO2-x materials were found to be excellent catalysts for complete SO2 conversion to elemental sulfur. Undoped nanocrystalline CeO2-x enabled light-off at 460 °C, a temperature ∼120 °C lower than that over polycrystalline CeO2, which is a novel effective catalyst itself. The high catalytic activity of the nanocrystals was associated with their high concentration of oxygen vacancies. Excellent poisoning resistance was also exhibited by the nanocrystalline CeO2-x samples. These materials have stable activity in the presence of excess CO2.

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