Lower-Temperature Catalytic Performance of Bimetallic Ni−Re/Al2O3Catalyst for Gasoline Reforming to Produce Hydrogen with the Inhibition of Methane Formation

2006 ◽  
Vol 20 (4) ◽  
pp. 1377-1381 ◽  
Author(s):  
Linsheng Wang ◽  
Kazuhisa Murata ◽  
Yasuyuki Matsumura ◽  
Megumu Inaba
Keyword(s):  
Catalytic Performance ◽  
Methane Formation ◽  
Lower Temperature ◽  
Gasoline Reforming

scholarly journals Selective Catalytic Oxidation of Lean-H2S Gas Stream to Elemental Sulfur at Lower Temperature

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 746
Author(s):  
Daniela Barba ◽  
Vincenzo Vaiano ◽  
Vincenzo Palma
Keyword(s):  
Fluorescence Analysis ◽  
Catalytic Performance ◽  
Oxidation Reactions ◽  
Inlet Concentration ◽  
X Ray Diffraction ◽  
Fixed Temperature ◽  
Raman Analysis ◽  
X Ray ◽  
Selective Catalytic Oxidation ◽  
Lower Temperature

Ceria-supported vanadium catalysts were studied for H2S removal via partial and selective oxidation reactions at low temperature. The catalysts were characterized by N2 adsorption at 77 K, Raman spectroscopy, X-ray diffraction techniques, and X-ray fluorescence analysis. X-ray diffraction and Raman analysis showed a good dispersion of the V-species on the support. A preliminary screening of these samples was performed at fixed temperature (T = 327 °C) and H2S inlet concentration (10 vol%) in order to study the catalytic performance in terms of H2S conversion and SO2 selectivity. For the catalyst that exhibited the higher removal efficiency of H2S (92%) together with a lower SO2 selectivity (4%), the influence of temperature (307–370 °C), contact time (0.6–1 s), and H2S inlet concentration (6–15 vol%) was investigated.

Oxidation of thiophene over copper-manganese mixed oxides

2009 ◽  
Vol 63 (2) ◽  
Author(s):  
Małgorzata Szynkowska ◽  
Aneta Węglińska ◽  
Elżbieta Wojciechowska ◽  
Tadeusz Paryjczak
Keyword(s):  
Noble Metals ◽  
Mixed Oxides ◽  
Diffraction Method ◽  
Catalytic Performance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Copper Manganese ◽  
Different Temperatures ◽  
Temperature Programmed ◽  
Lower Temperature

AbstractCommercial hopcalite calcined at different temperatures and hopcalite modified with noble metals (Pt, Pd, and Au) were studied in oxidation of thiophene. Surface and bulk properties of catalysts were studied using temperature-programmed reduction (TPRH2), X-ray diffraction method (XRD) and thermal analysis (TG-DTA-MS). It was shown that calcined samples displayed higher activity in comparison with commercial untreated hopcalite; however, a lower temperature of calcination was favourable. High temperature of thermal treatment induced an increase in the crystallinity and a decrease in the surface area of the samples, and, as a consequence, the loss of catalysts activity. Moreover, marked improvement in the catalytic performance of platinum and palladium modified catalysts in relation to base hopcalite was observed. The obtained results indicate that the higher activity of samples containing Pt and Pd was accompanied by better reducibility of the catalysts.

Production of γ-Valerolactone from Methyl Levulinate via Catalytic Transfer Hydrogenation on Nickel-Copper Oxide Catalyst

2016 ◽  
Vol 872 ◽  
pp. 187-190
Author(s):  
Worapak Tanwongwal ◽  
Sanchai Kuboon ◽  
Wasawat Kraithong ◽  
Apiluck Eiad-Ua
Keyword(s):  
Copper Oxide ◽  
Calcination Temperature ◽  
Catalytic Performance ◽  
Atomic Ratio ◽  
Transfer Hydrogenation ◽  
Catalytic Transfer Hydrogenation ◽  
Methyl Levulinate ◽  
Nickel Copper ◽  
Catalytic Transfer ◽  
Lower Temperature

γ-Valerolactone (GVL) is successfully produced via catalytic transfer hydrogenation from methyl levulinate on nickel copper oxide catalysts with the comparable result to that of Raney-nickel. This catalyst is prepared at lower temperature (lower than 1000oC) and pretreatment is not required before its use. Among different calcination temperature, Ni-Cu-O which synthesis at 700oC shows the best catalytic performance with 100% methyl levulinate conversion and more than 95% GVL yield and characterization result was shows this calcination temperature was affect catalyst to highest crystallization and surface area. The study of atomic ratio effect indicates that nickel-copper oxide which had nickel oxide more than copper oxide is better for this reaction.

scholarly journals Improving the Performance of BaMnO3 Perovskite as Soot Oxidation Catalyst Using Carbon Black during Sol-Gel Synthesis

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 219
Author(s):  
Verónica Torregrosa-Rivero ◽  
María-Salvadora Sánchez-Adsuar ◽  
María-José Illán-Gómez
Keyword(s):  
Carbon Black ◽  
Catalyst Deactivation ◽  
Sol Gel ◽  
Soot Oxidation ◽  
Catalytic Performance ◽  
Oxidation Catalyst ◽  
Bet Surface Area ◽  
Calcination Temperatures ◽  
Lower Temperature ◽  
Reference Catalyst

A series of BaMnO3 solids (BM-CX) were prepared by a modified sol-gel method in which a carbon black (VULCAN XC-72R), and different calcination temperatures (600 °C–850 °C) were used. The fresh and used catalysts were characterized by ICP-OES, XRD, XPS, FESEM, TEM, O2-TPD and H2- TPR-. The characterization results indicate that the use of low calcination temperatures in the presence of carbon black allows decreasing the sintering effects and achieving some improvements regarding BM reference catalyst: (i) smaller average crystal and particles size, (ii) a slight increase in the BET surface area, (iii) a decrease in the macropores diameter range and, (iv) a lower temperature for the reduction of manganese. The hydrogen consumption confirms Mn(III) and Mn(IV) are presented in the samples, Mn(III) being the main oxidation state. The BM-CX catalysts series shows an improved catalytic performance regarding BM reference catalyst for oxidation processes (NO to NO2 and NO2-assisted soot oxidation), promoting higher stability and higher CO2 selectivity. BM-C700 shows the best catalytic performance, i.e., the highest thermal stability and a high initial soot oxidation rate, which decreases the accumulation of soot during the soot oxidation and, consequently, minimizes the catalyst deactivation.

scholarly journals Remarkable Enhancement In The N2- Selectivity of NH3-SCR Over The CeNb3Fe0.3/TiO2 Catalyst In The Presence of Chlorobenzene

2021 ◽  
Author(s):  
Pengchao Zang ◽  
Jun Liu ◽  
Xiaoqing Liu ◽  
Guojie Zhang ◽  
Jianjun Chen ◽  
...  
Keyword(s):  
Sol Gel ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Oxidation Activity ◽  
In Situ Drifts ◽  
Nh3 Scr ◽  
Adsorbed Oxygen Species ◽  
Initial Stage ◽  
Lower Temperature

Abstract The simultaneous removal of NOx and dioxins is the frontier of environmental catalysis, which is still in the initial stage and poses several challenges. In this study, a series of CeNb3Fex/TiO2 (x = 0, 0.3, 0.6, and 1.0) catalysts were prepared by the sol-gel method and examined for the synergistic removal of NOx and chlorobenzene. The CeNb3Fe0.3/TiO2 catalyst exhibits an optimum catalytic performance, with an NOx conversion greater than 95 % at 260-380 °C. It also exhibited an optimal CB oxidation activity, in which CB promoted both the NOx conversion and N2 selectivity below 250 °C. Moreover, the more favourable ratios of Ce4+ to Ce3+, and plentiful surface adsorbed oxygen species are the reasons why CeNb3Fe0.3/TiO2 catalyst has better catalytic activity than other catalysts at lower temperature. Simultaneously, owing to the modulation of Fe to the redox properties of Ce and Nb, the large number of oxygen vacancies and acid sites, the CeNb3Fe0.3/TiO2 catalyst is is beneficial to NOx reduction and CB oxidation. Further, the results of in situ DRIFTS study reveal the NH3-SCR reactions over CeNb3Fex/TiO2 catalysts are mainly controlled by the L-H mechanism (< 200 °C) and E-R mechanism (> 200 °C), respectively.

Effect of Preparation Conditions on the n-Pentane Isomerisation Performance of Pt-S2O82–/ZrO2–Al2O3 Catalysts Prepared by the Microemulsion Method

2017 ◽  
Vol 42 (1) ◽  
pp. 14-22
Author(s):  
Hua Song ◽  
Yao Meng ◽  
Hualin Song ◽  
Feng Li
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Space Velocity ◽  
Catalytic Performance ◽  
Catalyst Preparation ◽  
Molar Ratio ◽  
Mass Ratio ◽  
Microemulsion Method ◽  
Preparation Conditions ◽  
Weight Hourly Space Velocity ◽  
Lower Temperature

Pt-promoted S2O82–/ZrO2–Al2O3 (SZA) catalysts were successfully prepared by the microemulsion (Pt-SZA-M) and impregnation (Pt-SZA-I) methods. The effects of the preparation parameters (surfactant-to-oil ratio, surfactant-to-cosurfactant ratio, types of cosurfactant and oil phase, etc.) on the catalytic activity of Pt-SZA-M catalysts in the isomerisation of n-pentane were investigated. The results showed that the optimal catalyst preparation conditions were: a cetyltrimethylammonium bromide (CTAB)/ n-butanol mass ratio of 4:6, a (CTAB + n-butanol)/cyclohexane mass ratio of 3:7, a content of H2PtCl6 solution in microemulsion of 3.6 wt% and a N2H5OH/H2PtCl6 molar ratio of 25:1. A comparison of the isopentane yield for Pt-SZA-M with that for Pt-SZA-I was also performed. The results showed that the microemulsion method led to smaller and more uniform Pt particles (4.5 nm) on the SZA. In comparison with Pt-SZA-I, the isopentane yield for Pt-SZA-M was increased by 13.5% at 180 °C, showing the catalytic performance of Pt-SZA-M at lower temperature was improved significantly. At a reaction temperature of 230 °C, a pressure of 2.0 MPa, a hydrogen/ n-pentane molar ratio of 4:1 and a weight hourly space velocity of 1.0 h−1, the yield of isopentane for Pt-SZA-M reached 60.8%.

Reactivity in the system carbon-hydrogen-methane

1967 ◽  
Vol 20 (8) ◽  
pp. 1561 ◽  
Author(s):  
JD Blackwood ◽  
BD Cullis ◽  
DJ McCarthy
Keyword(s):  
Surface Area ◽  
Active Surface ◽  
Active Surface Area ◽  
Methane Formation ◽  
Forward Reaction ◽  
Reversible Process ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Increasing Temperature ◽  
Initial Reactivity

Experimental work has shown that the rate constant k* = R/p1 (where R is the rate of methane formation and p1 is the hydrogen partial pressure) for the forward reaction, C + 2H2 ↔ CH4, is a function of the temperature of char preparation and reaction and can be expressed by ���������������������� k* = w exp(b/Tp)exp(-c/Tp) where w, b, and c are constants; Tp and Tg are the temperatures, in �K, of char preparation and gasification respectively; and Tg≤Tp. Chars which have been gasified at a given temperature and then exposed to a higher temperature do not show their initial reactivity when returned to the lower temperature. The deactivation of the char, as evidenced by a measurable decrease in active surface area, is a non-reversible process. Approximate values of the active surface area per unit mass of char have been calculated, and a linear relationship between reactivity and active surface area has been found experimentally. Both the forward and reverse processes proceed by chemisorption of either methane or hydrogen on the same type of active site, and the nature of the sites is unchanged by temperature, although their number decreases with increasing temperature and as a result, the equilibrium is independent of char type. The value of the heat of adsorption of hydrogen on carbon, calculated from the experimental results, was approximately 7 kcal mole-1.

Silicon Tetrachloride Synthesis from Rice Hulls: Transmission and Scanning Electron Microscope Study

1972 ◽  
Vol 30 ◽  
pp. 236-237 ◽  
Author(s):  
Richard S. Thomas ◽  
Prabir K. Basu ◽  
Francis T. Jones
Keyword(s):  
Silicon Tetrachloride ◽  
Silica Sand ◽  
Mineral Matter ◽  
Chemical Heterogeneity ◽  
Scanning Electron Microscope Study ◽  
Rice Hulls ◽  
Hull Structure ◽  
Lower Temperature ◽  
Image Position ◽  
Disposal Problem

Silicon tetrachloride, used in industry for the production of highest purity silicon and silica, is customarily manufactured from silica-sand and charcoal.SiCl4 can also be made from rice hulls, which contain up to 20 percent silica and only traces of other mineral matter. Hulls, after carbonization, actually prove superior as a starting material since they react at lower temperature. This use of rice hulls may offer a new, profitable solution for a rice mill byproduct disposal problem.In studies of the reaction kinetics with carbonized hulls, conversion of SiO2 to SiCl4 was found to proceed within a few minutes to a constant, limited yield which depended reproducibly on the ambient temperature of the reactor. See Fig. 1. This suggested that physical or chemical heterogeneity of the silica in the hull structure might be involved.

The design and catalytic performance of molybdenum active sites on an MCM-41 framework for the aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

2019 ◽  
Vol 9 (3) ◽  
pp. 811-821 ◽  
Author(s):  
Zhao-Meng Wang ◽  
Li-Juan Liu ◽  
Bo Xiang ◽  
Yue Wang ◽  
Ya-Jing Lyu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Aerobic Oxidation ◽  
Catalytic Performance ◽  
Mcm 41

The catalytic activity decreases as –(SiO)3Mo(OH)(O) > –(SiO)2Mo(O)2 > –(O)4–MoO.

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