scholarly journals Combined Reforming of Clean Biogas over Nanosized Ni–Rh Bimetallic Clusters

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1345
Author(s):  
Nicola Schiaroli ◽  
Carlo Lucarelli ◽  
Maria Carmela Iapalucci ◽  
Giuseppe Fornasari ◽  
Antonio Crimaldi ◽  
...  
Keyword(s):  
Active Sites ◽  
Carbon Deposition ◽  
Bimetallic Nanoparticles ◽  
Catalyst Activity ◽  
Dry Reforming ◽  
Bimetallic Clusters ◽  
Low Carbon ◽  
Reaction Conditions ◽  
Active Particles ◽  
Highly Dispersed

The combined steam/dry reforming of clean biogas (CH4/CO2 = 50/50 v/v) represents an innovative way to produce synthesis gas (CO + H2) using renewable feeds, avoiding to deplete the fossil resources and increase CO2 pollution. The reaction was carried out to optimize the reaction conditions for the production of a syngas with a H2/CO ratio suitable for the production of methanol or fuels without any further upgrading. Ni-Rh/Mg/Al/O catalysts obtained from hydrotalcite-type precursors showed high performances in terms of clean biogas conversion due to the formation of very active and resistant Ni-Rh bimetallic nanoparticles. Through the utilization of a {Ni10Rh(CO)19}{(CH3CH2)4N}3 cluster as a precursor of the active particles, it was possible to promote the Ni-Rh interaction and thus obtain low metal loading catalysts composed by highly dispersed bimetallic nanoparticles supported on the MgO, MgAl2O4 matrix. The optimization of the catalytic formulation improved the size and the distribution of the active sites, leading to a better catalyst activity and stability, with low carbon deposition with time-on-stream.

scholarly journals Bio-DEE Synthesis and Dehydrogenation Coupling of Bio-Ethanol to Bio-Butanol over Multicomponent Mixed Metal Oxide Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 660
Author(s):  
Izabela S. Pieta ◽  
Alicja Michalik ◽  
Elka Kraleva ◽  
Dusan Mrdenovic ◽  
Alicja Sek ◽  
...  
Keyword(s):  
Active Sites ◽  
Internal Combustion Engines ◽  
Mixed Oxides ◽  
Catalyst Activity ◽  
Product Distribution ◽  
Coke Deposition ◽  
Precipitation Method ◽  
Mixed Metal Oxide ◽  
Low Carbon ◽  
Municipal Solid Wastes

Within the Waste2Fuel project, innovative, high-performance, and cost-effective fuel production methods from municipal solid wastes (MSWs) are sought for application as energy carriers or direct drop-in fuels/chemicals in the near-future low-carbon power generation systems and internal combustion engines. Among the studied energy vectors, C1-C2 alcohols and ethers are mainly addressed. This study presents a potential bio-derived ethanol oxidative coupling in the gas phase in multicomponent systems derived from hydrotalcite-containing precursors. The reaction of alcohol coupling to ethers has great importance due to their uses in different fields. The samples have been synthesized by the co-precipitation method via layered double hydroxide (LDH) material synthesis, with a controlled pH, where the M(II)/M(III) ≈ 0.35. The chemical composition and topology of the sample surface play essential roles in catalyst activity and product distribution. The multiple redox couples Ni2+/Ni3+, Cr2+/Cr3+, Mn2+/Mn3+, and the oxygen-vacant sites were considered as the main active sites. The introduction of Cr (Cr3+/Cr4+) and Mn (Mn3+/Mn4+) into the crystal lattice could enhance the number of oxygen vacancies and affect the acid/base properties of derived mixed oxides, which are considered as crucial parameters for process selectivity towards bio-DEE and bio-butanol, preventing long CH chain formation and coke deposition at the same time.

scholarly journals One-Step Synthesis of Highly Dispersed and Stable Ni Nanoparticles Confined by CeO2 on SiO2 for Dry Reforming of Methane

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5956
Author(s):  
Chengyang Zhang ◽  
Renkun Zhang ◽  
Hui Liu ◽  
Qinhong Wei ◽  
Dandan Gong ◽  
...  
Keyword(s):  
Carbon Deposition ◽  
Combustion Method ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Solution Combustion ◽  
Spatial Confinement ◽  
Oxide Interfaces ◽  
Highly Dispersed ◽  
One Step ◽  
The One

Sintering and carbon deposition are the two main ways to deactivate Ni-based catalysts during methane reforming. Herein, a stable Ni-CeO2/SiO2(CSC) catalyst was prepared by a one-step colloidal solution combustion method (CSC) and used for dry reforming of methane. In the catalyst, the small Ni particles were confined by CeO2 particles and highly dispersed on the surface of SiO2, forming a spatial confinement structure with a rich Ni-CeO2 interface in the catalyst. The Ni-CeO2/SiO2(CSC) catalyst prepared by the one-step CSC method exhibited superior activity at 700 °C during dry reforming of methane, and the performance of the catalyst was stable after 20 h of reaction with only a small amount of carbon deposition present (1.8%). Due to the spatial confinement effect, Ni was stable and less than 5 nm during reaction. The small Ni particle size and rich Ni-CeO2 interface reduced the rate of carbon deposition. This colloidal combustion method could be applied to prepare stable metal-based catalysts with rich metal–oxide interfaces for high-temperature reactions.

scholarly journals A Review on the Hydroisomerisasion of n-Parafins over Supported Metal Catalysts

2021 ◽  
Vol 15 (2) ◽  
pp. 141
Author(s):  
Muhammad Safaat ◽  
Indri Badria Adilina ◽  
Silvester Tursiloadi
Keyword(s):  
Active Sites ◽  
Noble Metals ◽  
Catalyst Activity ◽  
Catalyst Support ◽  
Metal Catalyst ◽  
Supported Metal Catalysts ◽  
Reaction Conditions ◽  
High Level ◽  
Long Chain ◽  
Supported Metal

Catalytic hydroisomerization of n-paraffin aims to produce branched paraffin isomers and suppress cracking reactions in the production of the low cloud point of biodiesel. The development of the type of metal and catalyst support, amount of metal loading, and reaction conditions are important to increase the catalyst activity. A high performace catalyst for hydroisomerization bears bifunctional characteristics with a high level of hydrogenation active sites and low acidity, maximizing the progress of hydroisomerization compared to the competitive cracking reaction. In addition, a catalyst support with smaller pore size can hinder large molecular structure isoparaffins to react on the acid site in the pore thus providing good selectivity for converting n-paraffin. Catalysts loaded with noble metals (Pt or Pd) showed significantly higher selectivity for hydroisomerization than non-noble transition metals such as Ni, Co, Mo and W. The reaction temperature and contact time are also important parameters in hydroisomerization of long chain paraffin, because long contact times and high temperatures tend to produce undesired byproducts of cracking. This review reports several examples of supported metal catalyst used in the hydroisomerization of long chain hydrocarbon n-paraffins under optimized reaction conditions, providing the best isomerization selectivity results with the lowest amount of byproducts. The role of various metals and their supports will be explained mainly for bifunctional catalysts.

scholarly journals Carbon Deposition Behavior of Ni Catalyst Prepared by Combustion Method in Slurry Methanation Reaction

Catalysts ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 570 ◽  
Author(s):  
Keming Ji ◽  
Fanhui Meng ◽  
Jiayao Xun ◽  
Ping Liu ◽  
Kan Zhang ◽  
...  
Keyword(s):  
Active Sites ◽  
Carbon Deposition ◽  
Catalyst Deactivation ◽  
Catalyst Surface ◽  
Catalyst Activity ◽  
Combustion Method ◽  
Carbon Films ◽  
Ni Catalyst ◽  
Temperature Programmed Oxidation ◽  
Methanation Reaction

Ni/Al2O3 catalyst prepared by combustion method was applied in a slurry methanation reaction to study the catalytic performance, especially the regeneration performance. The catalyst properties were characterized by (X-Ray diffraction) XRD, Inductively coupled plasma atomic emission spectrometer (ICP-AES), Nitrogen adsorption-desorption, Transmission electron microscopy (TEM), Thermogravimetric analysis (TG/DTG), Temperature programmed oxidation (TPO), and H2 chemisorption before and after reaction. The results show that the catalyst deactivation was mainly due to carbon deposition, which exhibited amorphous carbon films and formed by the disproportionation of CO. The carbon deposition was formed on the catalyst surface and existed as carbon films during the reaction, then it gradually separated from the catalyst surface, generated an overlapping multi-layer three-dimensional carbon structure, which covered the active site and blocked the pores. As a result, the metal surface area of catalyst decreases, as well as the activity. The carbon deposition could be removed by oxidative calcination without destroying the catalyst structure, the active sites could be re-exposed and the catalyst activity could be recovered.

scholarly journals Critical Review of Low-Temperature CO Oxidation and Hysteresis Phenomenon on Heterogeneous Catalysts

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 660 ◽  
Author(s):  
Rola Al Soubaihi ◽  
Khaled Saoud ◽  
Joydeep Dutta
Keyword(s):  
Low Temperature ◽  
Co Oxidation ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Activity ◽  
Cost Effective ◽  
Hysteresis Phenomenon ◽  
Reaction Conditions ◽  
Kinetic Oscillations ◽  
Low Temperature Co Oxidation

There is a growing demand for new heterogeneous catalysts for cost-effective catalysis. Currently, the hysteresis phenomenon during low-temperature CO oxidation is an important topic in heterogeneous catalysis. Hysteresis provides important information about fluctuating reaction conditions that affect the regeneration of active sites and indicate the restoration of catalyst activity. Understanding its dynamic behavior, such as hysteresis and self-sustained kinetic oscillations, during CO oxidation, is crucial for the development of cost-effective, stable and long-lasting catalysts. Hysteresis during CO oxidation has a direct influence on many industrial processes and its understanding can be beneficial to a broad range of applications, including long-life CO2 lasers, gas masks, catalytic converters, sensors, indoor air quality, etc. This review considers the most recent reported advancements in the field of hysteresis behavior during CO oxidation which shed light on the origin of this phenomenon and the parameters that influence the type, shape, and width of the conversion of the hysteresis curves.

The role of carbon deposition on precious metal catalyst activity during dry reforming of biogas

2007 ◽  
Vol 129 (3-4) ◽  
pp. 391-396 ◽  
Author(s):  
F BARRAI ◽  
T JACKSON ◽  
N WHITMORE ◽  
M CASTALDI
Keyword(s):  
Precious Metal ◽  
Carbon Deposition ◽  
Catalyst Activity ◽  
Dry Reforming ◽  
Metal Catalyst

scholarly journals Dry Reforming of Methane over Carbon Fibre-Supported CeZrO2, Ni-CeZrO2, Pt-CeZrO2 and Pt-Ni-CeZrO2 Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 563
Author(s):  
Paulina Jagódka ◽  
Krzysztof Matus ◽  
Michał Sobota ◽  
Agata Łamacz
Keyword(s):  
Active Sites ◽  
Noble Metals ◽  
Carbon Deposition ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Metal Catalyst ◽  
Catalytic Support ◽  
Reverse Water Gas Shift ◽  
Proper Design ◽  
Parallel Reactions

Dry reforming of methane (DRM) is one of the most important processes allowing transformation of two most potent greenhouse gases into a synthesis gas. The CH4 and CO2 are converted at high temperatures in the presence of a metal catalyst (usually Ni, also promoted with noble metals, supported over various oxides). The DRM process is not widely used in the gas processing industry because of prompt deactivation of the catalyst owing to carbon deposition and the blockage of the metal active sites. This problem can be hindered by proper design of the catalyst in terms, e.g., of its composition and by providing strong interaction between active metal and catalytic support. The properties of the latter are also crucial for the catalyst’s performance in DRM and the occurrence of parallel reactions such as reverse water gas shift, CO2 deoxidation or carbon formation. In this paper we show for the first time the DRM performance of the ceria-zirconia and metal (Ni and/or Pt) supported on carbon fibres. The obtained Ni and Ni-Pt containing catalysts showed relatively high activity in the studied reaction and high resistance towards carbon deposition.

scholarly journals Room-Temperature Metathesis of Ethylene with 2-Butene to Propene Over MoOx-Based Catalysts: Mixed Oxides as Perspective Support Materials

2021 ◽  
Author(s):  
Tatiana Otroshchenko ◽  
Qiyang Zhang ◽  
Evgenii V. Kondratenko
Keyword(s):  
Room Temperature ◽  
Mixed Oxides ◽  
Catalyst Activity ◽  
Lattice Defects ◽  
Intrinsic Activity ◽  
Metathesis Reaction ◽  
Acidic Properties ◽  
Reaction Conditions ◽  
Support Materials ◽  
Highly Dispersed

AbstractWe investigated the effect of supports based on ZrO2, TiO2, Al2O3, and SiO2 on the rate of propene formation in the metathesis of ethylene with 2-butene at 50 °C over Mo-containing catalysts possessing highly dispersed MoOx. Large improvements in this rate were achieved when using supports composed of mixed oxides (ZrO2–SiO2, ZrO2–PO4, TiO2–SiO2; Al2O3–SiO2) rather than of individual oxides (ZrO2, TiO2, Al2O3, SiO2). Although previous literature studies dealing with the metathesis reaction over Al2O3- or SiO2-suppported catalysts at higher temperatures suggest the importance of redox or acidic properties of supported MoOx species for catalyst activity, we were not able to establish any general direct correlation in this regard. Contrarily, the rate of propene formation can be significantly enhanced when promoting supports with an oxide promoter. We suggest that the created support lattice defects may facilitate the transformation of MoOx to Mo carbenes under reaction conditions or improve the intrinsic activity of the latter. Graphic Abstract

Diffuse Reflectance FT-IR Characterization of Active Sites under Reaction Conditions: The Production of Oxygenates in the CO/H2 Reaction

1994 ◽  
Vol 48 (10) ◽  
pp. 1208-1212 ◽  
Author(s):  
J. J. Benítez ◽  
I. Carrizosa ◽  
J. A. Odriozola
Keyword(s):  
Infrared Spectra ◽  
Active Sites ◽  
Diffuse Reflectance ◽  
Reaction Conditions ◽  
In Situ Drifts ◽  
Ft Ir

The reactivity of a Lu2O3-promoted Rh/Al2O3 catalyst in the CO/H2 reaction is reported. Methane, heavier hydrocarbons, methanol, and ethanol are obtained. In situ DRIFTS has been employed to record the infrared spectra under the actual reaction conditions. The structure of the observed COads DRIFTS bands has been resolved into its components. The production of oxygenates (methanol and ethanol) has been correlated with the results of the deconvolution calculation. Specific sites for the production of methanol and ethanol in the CO/H2 reaction over a Rh,Lu2O3/Al2O3 catalyst are proposed.

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