scholarly journals Hydrotalcite-Type Materials Electrodeposited on Open-Cell Metallic Foams as Structured Catalysts

Inorganics ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 74 ◽  
Author(s):  
Phuoc Ho ◽  
Erika Scavetta ◽  
Domenica Tonelli ◽  
Giuseppe Fornasari ◽  
Angelo Vaccari ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
H2 Production ◽  
High Specific Surface Area ◽  
Metallic Foams ◽  
Open Cell ◽  
Structured Catalysts ◽  
Fundamental Understanding ◽  
Acidic Sites ◽  
Coating Procedure

Structured catalysts based on hydrotalcite-derived coatings on open-cell metallic foams combine tailored basic/acidic sites, relatively high specific surface area and/or metal dispersion of the coating as well as low pressure drop and enhanced heat and mass transfer of the 3D metallic support. The properties of the resulting structured catalysts depend on the coating procedure. We have proposed the electro-base generation method for in situ and fast precipitation of Ni/Al and Rh/Mg/Al hydrotalcite-type materials on FeCrAlloy foams, which after calcination at high temperature give rise to structured catalysts for syngas (CO + H2) production through Steam Reforming and Catalytic Partial Oxidation of CH4. The fundamental understanding of the electrochemical-chemical reactions relevant for the electrodeposition and the influence of electrosynthesis parameters on the properties of the as-deposited coatings as well the resulting structured catalysts and, hence, on their catalytic performance, were summarized.

The Application of Mesoporous ZSM-5 Zeolite in the ULSD Catalysts

2020 ◽  
Vol 4 (4) ◽  
pp. 1-3
Author(s):  
Liu L
Keyword(s):  
Catalytic Performance ◽  
Nitrogen Compounds ◽  
In Situ Ftir ◽  
X Ray Diffraction ◽  
N2 Adsorption ◽  
X Ray ◽  
Acidic Sites ◽  
Adsorption Desorption ◽  
Al2o3 Catalyst

The mesoporous ZSM-5 zeolite containing MoCoP/Al2O3 catalyst (C12-ZSM5) with the mixture of Al2O3 and mesoporous ZSM- 5 zeolite as carrier was synthesized. The catalytic performance of C12-ZSM5 catalyst was evaluated by the hydrodesulfurization (HDS) of different diesel feedstock. The carriers and catalysts were characterized by N2 adsorption-desorption, pyridine-FTIR, X-ray diffraction (XRD) and CO in-situ FTIR (CO-FTIR) techniques. Results showed that mesoporous ZSM-5 can improve the acidity of the catalyst and increase the number of MoCoS active phases. The C12-ZSM5 catalyst had low HDS and HDN activity, because the acidic sites of mesoporous ZSM-5 were easily occupied by nitrogen compounds. The HDS activity of C12-ZSM5 catalyst was fully exploited by using graded packing technology, the sulfur content of product oil was 5.9 ng/μL. The relative HDS activity of C12-ZSM5 catalyst is 1.47 times that of FHUDS-8 catalyst.

scholarly journals CO2 Hydrogenation to Methanol over La2O3-Promoted CuO/ZnO/Al2O3 Catalysts: A Kinetic and Mechanistic Study

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 183 ◽  
Author(s):  
Marios Kourtelesis ◽  
Kalliopi Kousi ◽  
Dimitris I. Kondarides
Keyword(s):  
Intermediate Formation ◽  
Reaction Rates ◽  
Catalytic Performance ◽  
High Specific Surface Area ◽  
Mechanistic Study ◽  
Partial Pressures ◽  
Surface Formate ◽  
Adsorption Of Co2 ◽  
In Situ Infrared Spectroscopy

The hydrogenation of CO2 to methanol has been investigated over CuO/ZnO/Al2O3 (CZA) catalysts, where a part of the Al2O3 (0, 25, 50, 75, or 100%) was substituted by La2O3. Results of catalytic performance tests obtained at atmospheric pressure showed that the addition of La2O3 generally resulted in a decrease of CO2 conversion and in an increase of methanol selectivity. Optimal results were obtained for the CZA-La50 catalyst, which exhibited a 30% higher yield of methanol, compared to the un-promoted sample. This was attributed to the relatively high specific surface area and porosity of this material, the creation of basic sites of moderate strength, which enhance adsorption of CO2 and intermediates that favor hydrogenation steps, and the ability of the catalyst to maintain a large part of the copper in its metallic form under reaction conditions. The reaction mechanism was studied with the use of in situ infrared spectroscopy (DRIFTS). It was found that the reaction proceeded with the intermediate formation of surface formate and methoxy species and that both methanol and CO were mainly produced via a common formate intermediate species. The kinetic behavior of the best performing CZA-La50 catalyst was investigated in the temperature range 190–230 °C as a function of the partial pressures of H2 (0.3–0.9 atm) and CO2 (0.05–0.20 atm), and a kinetic model was developed, which described the measured reaction rates satisfactorily.

scholarly journals Honeycomb Structured Catalysts for H2 Production via H2S Oxidative Decomposition

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 488 ◽  
Author(s):  
Vincenzo Palma ◽  
Daniela Barba ◽  
Vincenzo Vaiano ◽  
Michele Colozzi ◽  
Emma Palo ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Dip Coating ◽  
H2 Production ◽  
Sem Analysis ◽  
Operating Conditions ◽  
Structured Catalysts ◽  
Structured Catalyst ◽  
Honeycomb Monolith ◽  
Different Temperatures ◽  
H2 Yield

Cordierite honeycomb structured catalysts were studied for the reaction of H2S decomposition in the presence of oxygen to obtain H2 and sulphur. An Al2O3-based washcoat was deposited on the honeycomb monolith by a dip-coating procedure. In particular, three different washcoat percentages (15, 20 and 30 wt%) were deposited on the structured carrier and the obtained samples were characterized by N2 adsorption and SEM analysis. The evaluation of the catalytic performance of the three samples was carried out at two different temperatures (1000 °C and 1100 °C). The sample with 30 wt% washcoat content showed the lowest SO2 selectivity at 1000 °C (<0.4%), whereas the H2S conversion and H2 yield values were very similar to those achieved for the samples at 15 and 20 wt% washcoat loading. Based on these results, additional tests were carried out on the catalyst with 30 wt% Al2O3-based washcoat loading, varying the contact time and the H2S inlet concentration to identify the operating conditions that minimize the SO2 formation, obtaining good H2S conversion and H2 yield. The comparison of the structured catalyst with the powder alumina sample has shown the same catalytic performance, exhibiting lower SO2 selectivity.

Ceramic monolith- and foam-structured catalysts via in-situ combustion deposition for energetic applications

2018 ◽  
Vol 42 (3) ◽  
pp. 405-418
Author(s):  
Cristina ITALIANO ◽  
Lidia PINO ◽  
Massimo LAGANÀ ◽  
Antonio VITA
Keyword(s):  
In Situ Combustion ◽  
Structured Catalysts

scholarly journals Insight into Active Centers and Anti-Coke Behavior of Niobium-Containing SBA-15 for Glycerol Dehydration

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 488
Author(s):  
Katarzyna Stawicka ◽  
Maciej Trejda ◽  
Maria Ziolek
Keyword(s):  
Coke Formation ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Silica Matrix ◽  
High Concentration ◽  
Active Centers ◽  
Acidic Sites ◽  
Glycerol Dehydration ◽  
Adsorption Desorption ◽  
Insight Into

Niobium containing SBA-15 was prepared by two methods: impregnation with different amounts of ammonium niobate(V) oxalate (Nb-15/SBA-15 and Nb-25/SBA-15 containing 15 wt.% and 25 wt.% of Nb, respectively) and mixing of mesoporous silica with Nb2O5 followed by heating at 500 °C (Nb2O5/SBA-15). The use of these two procedures allowed obtaining materials with different textural/surface properties determined by N2 adsorption/desorption isotherms, XRD, UV-Vis, pyridine, and NO adsorption combined with FTIR spectroscopy. Nb2O5/SBA-15 contained exclusively crystalline Nb2O5 on the SBA-15 surface, whereas the materials prepared by impregnation had both metal oxide and niobium incorporated into the silica matrix. The niobium species localized in silica framework generated Brønsted (BAS) and Lewis (LAS) acid sites. The inclusion of niobium into SBA-15 skeleton was crucial for the achievement of high catalytic performance. The strongest BAS were on Nb-25/SBA-15, whereas the highest concentration of BAS and LAS was on Nb-15/SBA-15 surface. Nb2O5/SBA-15 material possessed only weak LAS and BAS. The presence of the strongest BAS (Nb-25/SBA-15) resulted in the highest dehydration activity, whereas a high concentration of BAS was unfavorable. Silylation of niobium catalysts prepared by impregnation reduced the number of acidic sites and significantly increased acrolein yield and selectivity (from ca. 43% selectivity for Nb-25/SBA-15 to ca. 61% for silylated sample). This was accompanied by a considerable decrease in coke formation (from 47% selectivity for Nb-25/SBA-15 to 27% for silylated material).

scholarly journals TiO2 Nanowires with Doped g-C3N4 Nanoparticles for Enhanced H2 Production and Photodegradation of Pollutants

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 254
Author(s):  
Liushan Jiang ◽  
Fanshan Zeng ◽  
Rong Zhong ◽  
Yu Xie ◽  
Jianli Wang ◽  
...  
Keyword(s):  
Environmental Governance ◽  
Fossil Fuels ◽  
H2 Production ◽  
Tio2 Nanowires ◽  
Photocatalytic Ability ◽  
Production Of Hydrogen ◽  
Growth Method ◽  
Renewable Hydrogen ◽  
Degradation Of Pollutants

With the rapid consumption of fossil fuels, along with the ever-increasing environmental pollution, it is becoming a top priority to explore efficient photocatalysts for the production of renewable hydrogen and degradation of pollutants. Here, we fabricated a composite of g-C3N4/TiO2 via an in situ growth method under the conditions of high-temperature calcination. In this method, TiO2 nanowires with a large specific surface area could provide enough space for loading more g-C3N4 nanoparticles to obtain C3N4/TiO2 composites. Of note, the g-C3N4/TiO2 composite could effectively photocatalyze both the degradation of several pollutants and production of hydrogen, both of which are essential for environmental governance. Combining multiple characterizations and experiments, we found that the heterojunction constructed by the TiO2 and g-C3N4 could increase the photocatalytic ability of materials by prompting the separation of photogenerated carriers. Furthermore, the photocatalytic mechanism of the g-C3N4/TiO2 composite was also clarified in detail.

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