scholarly journals Comparison of Two Preparation Methods on Catalytic Activity and Selectivity of Ru-Mo/HZSM5 for Methane Dehydroaromatization

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Lucia M. Petkovic ◽  
Daniel M. Ginosar
Keyword(s):  
Molybdenum Carbide ◽  
Molybdenum Trioxide ◽  
Catalyst Activity ◽  
Catalytic Performance ◽  
Preparation Methods ◽  
Ammonium Heptamolybdate ◽  
Temperature Programmed Oxidation ◽  
Methane Dehydroaromatization ◽  
Acidic Sites ◽  
Temperature Programmed

Catalytic performance of Mo/HZSM5 and Ru-Mo/HZSM5 catalysts prepared by vaporization-deposition of molybdenum trioxide and impregnation with ammonium heptamolybdate was analyzed in terms of catalyst activity and selectivity, nitrogen physisorption analyses, temperature-programmed oxidation of carbonaceous residues, and temperature-programmed reduction. Vaporization-deposition rendered the catalyst more selective to ethylene and coke than the catalyst prepared by impregnation. This result was assigned to lower interaction of molybdenum carbide with the zeolite acidic sites.

scholarly journals Nickel-Catalysed Vapour-Phase Hydrogenation of Furfural, Insights into Reactivity and Deactivation

2020 ◽  
Vol 63 (15-18) ◽  
pp. 1446-1462 ◽  
Author(s):  
Kathryn L. MacIntosh ◽  
Simon K. Beaumont
Keyword(s):  
Furfuryl Alcohol ◽  
Copper Chromite ◽  
Catalyst Support ◽  
Nickel Catalysts ◽  
Vapour Phase ◽  
X Ray Diffraction ◽  
Temperature Programmed Oxidation ◽  
Acidic Sites ◽  
Supported Nickel Catalysts ◽  
Temperature Programmed

AbstractFurfural is a key bioderived platform molecule, and its hydrogenation affords access to a number of important chemical intermediates that can act as “drop-in” replacements to those derived from crude oil or novel alternatives with desirable properties. Here, the vapour phase hydrogenation of furfural to furfuryl alcohol at 180 °C over standard impregnated nickel catalysts is reported and contrasted with the same reaction over copper chromite. Whilst the selectivity to furfuryl alcohol of the unmodified nickel catalysts is much lower than for copper chromite as expected, the activity of the nickel catalysts in the vapour phase is significantly higher, and the deactivation profile remarkably similar. In the case of the supported nickel catalysts, possible contribution to the deactivation by acidic sites on the catalyst support is discounted based on the similarity of deactivation kinetics on Ni/SiO2 with those seen for less acidic Ni/TiO2 and Ni/CeO2. Powder X-ray diffraction is used to exclude sintering as a primary deactivation pathway. Significant coking of the catalyst (~ 30 wt% over 16 h) is observed using temperature programmed oxidation. This, in combination with the solvent extraction analysis and infrared spectroscopy of the coked catalysts points to deactivation by polymeric condensation products of (reactant or) products and hydrocarbon like coke. These findings pave the way for targeted modification of nickel catalysts to use for this important biofeedstock-to-chemicals transformation.

Oxygen Radicals Occlusion/Release Behavior of Nanoporous Aluminosilicate, Ca12Al14-XSiXO33+0.5X (0≦X≦4)

2006 ◽  
Vol 45 ◽  
pp. 2105-2109
Author(s):  
Makoto Nagashima ◽  
Daisuke Hirabayashi ◽  
Kenzi Suzuki
Keyword(s):  
Catalytic Activity ◽  
Oxygen Content ◽  
Oxygen Radicals ◽  
Catalytic Performance ◽  
Oxygen Release ◽  
Release Behavior ◽  
Temperature Programmed Reduction ◽  
Temperature Programmed Oxidation ◽  
Temperature Range ◽  
Temperature Programmed

Oxygen radicals occlusion / release behavior of nanoporous aluminosilicate, Ca12Al14-XSiXO33+0.5X (0≦X≦4), synthesized under different condition was examined by the temperature programmed reduction (TPR) in an atmosphere of hydrogen in the temperature range of 200-1000°C and temperature programmed oxidation (TPO) measurement at 800°C. From the TPR results of Ca12Al14O33 (X=0) and Ca12Al10Si4O35 (X=4), it was found that there were three oxygen release peaks, denoted as α, β and γ, on each sample and the peaks appeared in the temperature range 300-420°C, 420-600°C, and 600-750°C, respectively. The oxygen contents of α and γ of samples were almost the same. However, the oxygen content of β in the sample with x = 4 was much larger, almost double, compared to that in x = 0. From the TPR, TPO results and catalytic performance, it was concluded that the oxygen content of β peak strongly influenced the catalytic activity of the nanoporous aluminosilicate in the propylene combustion.

Influence of Final Nitriding Temperature on the Preparation and the Catalytic Performance of CoMoNx/CNTs for Ammonia Decomposition

2012 ◽  
Vol 557-559 ◽  
pp. 1514-1517
Author(s):  
Zhao Hui Zhao ◽  
Han Bo Zou ◽  
Wei Ming Lin
Keyword(s):  
Physical Adsorption ◽  
Catalyst Activity ◽  
Catalytic Performance ◽  
Ammonia Decomposition ◽  
Molybdenum Nitride ◽  
Nitriding Temperature ◽  
X Ray Diffraction ◽  
Cobalt Molybdenum Nitride ◽  
Temperature Programmed ◽  
Temperature Programmed Reaction

A series of cobalt-molybdenum nitride catalysts were prepared using Co-Mo oxide precursors via temperature-programmed reaction in N2-H2 mixed gases. The catalysts were characterized by N2 physical adsorption, X-ray diffraction, temperature-programmed desorption of H2. Their catalytic performance was evaluated in the model reaction of ammonia decomposition. The influence of the final nitriding temperatures on the surface properties and the catalytic perfomance of CoMoNx/CNTs were described. The catalyst nitrided at 650°C shows the best catalytic performance. The results indicated that a suitable final nitriding temperature contributes directly to the formation of nitrides and favor the catalyst activity.

A Comparison of the H3PW12O40/MCM-41 and HY Zeolite for Alkenylation of p-Xylene with Phenylacetylene

2013 ◽  
Vol 634-638 ◽  
pp. 377-381 ◽  
Author(s):  
Zhong Kui Zhao ◽  
Yi Tao Dai
Keyword(s):  
Flow Reactor ◽  
Fixed Bed ◽  
Catalytic Performance ◽  
Hy Zeolite ◽  
Ultrasonic Assisted ◽  
Acidic Sites ◽  
High Dispersity ◽  
Catalytic Stability ◽  
Temperature Programmed ◽  
Mcm 41

The initial activity, selectivity, and especially catalytic stability of mesoporous MCM-41 supported phosphotungstic acid (HPW) prepared by ultrasonic-assisted impregnation (UAI) method and the HY zeolite were contrastively investigated for alkenylation of p-xylene with phenylacetylene in a fixed-bed continuous flow reactor. N2 adsorption-desorption, FT-IR, X-ray diffraction (XRD) and NH3 temperature-programmed (NH3-TPD) desorption characterization techniques were employed to explore the relationship of catalyst nature and catalytic performance in alkenylation. Results illustrate that the as-prepared HPW/MCM-41 catalyst exhibits notably superior catalytic activity, selectivity and stability to microporous HY zeolite, ascribed to its well-ordered mesoporous architecture, appropriate acidic sites and high dispersity of HPW phase.

scholarly journals Catalytic Performance of CPM-200-In/Mg in the Cycloaddition of CO2 and Epoxides

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 430
Author(s):  
Yunjang Gu ◽  
Youngson Choe ◽  
Dae-Won Park
Keyword(s):  
Density Functional ◽  
Heterogeneous Catalysts ◽  
Cycloaddition Reaction ◽  
Catalytic Performance ◽  
X Ray Diffraction ◽  
Solvent Free Conditions ◽  
Simple Filtration ◽  
Acidic Sites ◽  
Metal Organic ◽  
Temperature Programmed

Crystalline porous materials (CPM)-200-In and CPM-200-In/Mg metal-organic frameworks (MOFs) were synthesized by a solvothermal method and were characterized by using powder X-ray diffraction (PXRD), FT-IR, Brunauer–Emmett–Teller (BET), temperature programmed desorption (TPD), TGA, XPS, and SEM-EDS. They were used as heterogeneous catalysts for the cycloaddition of CO2 with epoxides and found to be highly efficient toward the cycloaddition reaction at moderate reaction conditions under solvent-free conditions. The catalyst was easily separated by a simple filtration and can be reused up to five consecutive times without any considerable decrease of its initial activity. CPM-200-In/Mg showed excellent catalytic performance in the cycloaddition reaction due to the synergistic role of the acidic sites and basic sites. A plausible reaction mechanism for the CPM-200-In/Mg MOF catalyzed cycloaddition reaction is proposed based on the experimental results and our previously reported DFT (Density Functional Theory) studies.

scholarly journals CO2 reforming of CH4 over M(Ca, Ba, Sr)xLa1-xNiO3 perovskites used as coke resistant catalyst precursor

2020 ◽  
pp. 40-40
Author(s):  
Ana Carolina Trevisani Souza ◽  
Marcelo da Silva Batista
Keyword(s):  
Catalytic Performance ◽  
Partial Substitution ◽  
High Catalytic Activity ◽  
Catalyst Precursor ◽  
Co2 Reforming ◽  
Temperature Programmed Oxidation ◽  
Co2 Reforming Of Ch4 ◽  
Co2 Reforming Of Methane ◽  
Temperature Programmed ◽  
Carbon Dioxide Co2

Methane (CH4) and carbon dioxide (CO2) are greenhouse gases that have been converted into synthesis gas for the production of oxygenated chemicals and hydrocarbons. In this paper, M(Ca, Ba, Sr)xLa1-xNiO3 (x=0.0, 0.3 and 0.5) doped perovskites were successfully synthesized as catalyst precursors aiming at high catalytic activity and stability in the CO2 reforming of methane. These perovskites were characterized by X-ray diffraction (XRD), temperature programmed reduction by H2 (H2-TPR) and O2-temperature programmed oxidation (TPO). Its activity and carbon suppression were investigated in the CO2 reforming of methane. Results showed formation of perovskite structure, but La2NiO4 spinel and NiO were also detected in doped perovskites. The Ca, Ba and Sr partial substitution has evident influence on the reduction behavior of perovskites. All the doped perovskites used as catalyst precursors had better catalytic performance than LaNiO3. However, increasing the doping content decreased activity. Among doped perovskites, Ca0.3La0.7NiO3 showed better catalytic performance for the methane reforming reaction.

Simultaneous Removal of NOx and PM over La1-xKxCo1-yMnyO3 Perovskite-Type Catalysts

2012 ◽  
Vol 550-553 ◽  
pp. 209-213
Author(s):  
Ting Ting Wang ◽  
Yan Xia Hong ◽  
Hong Liang ◽  
Shu Hua Li ◽  
Qi Fen Chen ◽  
...  
Keyword(s):  
Combustion Method ◽  
Catalytic Performance ◽  
Simultaneous Removal ◽  
Temperature Programmed Oxidation ◽  
Average Oxidation State ◽  
Ft Ir ◽  
Temperature Programmed ◽  
Perovskite Type ◽  
Reduction Percentage ◽  
Catalytic Performances

To study the effect of K and Mn substitution on simultaneous removal of NOx and particulate materials (PM), a series of La1-xKxCo1-yMnyO3 (x, y=0.1, 0.2, 0.3, 0.4, 0.5) perovskite-type catalysts were synthesized by complex-combustion method. The catalytic performances of the catalysts were evaluated by temperature-programmed oxidation reaction (TPO). And the catalysts were characterized by XRD, FT-IR, H2-TPR techniques. After introducing K and Mn to LaCoO3 simultaneously, all the samples possess perovskite-type structures and the B-site ions form higher average oxidation state enhancing the catalytic performance obviously. La0.8K0.2Co0.7Mn0.3O3 catalyst exhibits not only the lowest T i(297 °C) temperature but also the lowest Tm (343 °C) temperature. Meanwhile, the NO reduction percentage over this catalyst can reach 97%.

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).

Selective catalytic reduction of NO by Co-Mn based nanocatalysts

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Vahid Zabihi ◽  
Mohammad Hasan Eikani ◽  
Mehdi Ardjmand ◽  
Seyed Mahdi Latifi ◽  
Alireza Salehirad
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Energy Dispersive ◽  
Diffraction Field ◽  
X Ray Diffraction ◽  
X Ray ◽  
Analysis Techniques ◽  
Acidic Sites ◽  
Temperature Window ◽  
Temperature Programmed

Abstract One of the most significant aspects in selective catalytic reduction (SCR) of nitrogen oxides (NOx) is developing suitable catalysts by which the process occurs in a favorable way. At the present work SCR reaction by ammonia (NH3-SCR) was conducted using Co-Mn spinel and its composite with Fe-Mn spinel, as nanocatalysts. The nanocatalysts were fabricated through liquid routes and then their physicochemical properties such as phase composition, degree of agglomeration, particle size distribution, specific surface area and also surface acidic sites have been investigated by X-ray diffraction, Field Emission Scanning Electron Microscope, Energy-dispersive X-ray spectroscopy, energy dispersive spectroscopy mapping, Brunauer–Emmett–Teller, temperature-programmed reduction (H2-TPR) and temperature-programmed desorption of ammonia (NH3-TPD) analysis techniques. The catalytic activity tests in a temperature window of 150–400 °C and gas hourly space velocities of 10,000, 18,000 and 30,000 h−1 revealed that almost in all studied conditions, CoMn2O4/FeMn2O4 nanocomposite exhibited better performance in SCR reaction than CoMn2O4 spinel.

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