Effect of Ni Reducibility on Anisole Hydrodeoxygenation Activity in the La-Ni/γ-Al2O3 Catalytic System

2019 ◽  
Vol 18 (2) ◽  
Author(s):  
Brett Pomeroy ◽  
Teri Doxtator ◽  
Jose E. Herrera ◽  
Dominic Pjontek
Keyword(s):  
Catalytic Activity ◽  
Catalytic System ◽  
Catalyst Surface ◽  
Reaction Pathway ◽  
Catalyst Characterization ◽  
Temperature Programmed Reduction ◽  
Visible Spectroscopy ◽  
Uv Visible ◽  
Temperature Programmed

Abstract The effect of lanthanum addition on the activity of a series of Ni/γ-Al2O3 catalysts for anisole hydrodeoxygenation (HDO) was evaluated. Catalyst characterization using hydrogen temperature-programmed reduction (H2-TPR) and UV-visible spectroscopy suggests that lanthanum incorporation results in the formation of larger metallic Ni domains in the catalyst surface, which in turn favour the direct anisole hydrogenation pathway to methoxycyclohexane. Despite the improvements to reducibility that resulted from the incorporation of La, the catalysts displayed lower selectivity towards cyclohexane, independent of total nickel loading. The catalytic activity results were rationalized in terms of a proposed reaction pathway where anisole is initially hydrogenated followed by sequential deoxygenation steps.

scholarly journals Precipitated K-Promoted Co–Mn–Al Mixed Oxides for Direct NO Decomposition: Preparation and Properties

Catalysts ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 592 ◽  
Author(s):  
Květa Jirátová ◽  
Kateřina Pacultová ◽  
Jana Balabánová ◽  
Kateřina Karásková ◽  
Anna Klegová ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Mixed Oxides ◽  
No Decomposition ◽  
Temperature Programmed Reduction ◽  
X Ray ◽  
Co2 Desorption ◽  
Metal Nitrates ◽  
Temperature Programmed ◽  
Desorption Method ◽  
Al Oxide

Direct decomposition of nitric oxide (NO) proceeds over Co–Mn–Al mixed oxides promoted by potassium. In this study, answers to the following questions have been searched: Do the properties of the K-promoted Co–Mn–Al catalysts prepared by different methods differ from each other? The K-precipitated Co–Mn–Al oxide catalysts were prepared by the precipitation of metal nitrates with a solution of K2CO3/KOH, followed by the washing of the precipitate to different degrees of residual K amounts, and by cthe alcination of the precursors at 500 °C. The properties of the prepared catalysts were compared with those of the best catalyst prepared by the K-impregnation of a wet cake of Co–Mn–Al oxide precursors. The solids were characterized by chemical analysis, DTG, XRD, N2 physisorption, FTIR, temperature programmed reduction (H2-TPR), temperature programmed CO2 desorption (CO2-TPD), X-ray photoelectron spectrometry (XPS), and the species-resolved thermal alkali desorption method (SR-TAD). The washing of the K-precipitated cake resulted in decreasing the K amount in the solid, which affected the basicity, reducibility, and non-linearly catalytic activity in NO decomposition. The highest activity was found at ca 8 wt.% of K, while that of the best K-impregnated wet cake catalyst was at about 2 wt.% of K. The optimization of the cake washing conditions led to a higher catalytic activity.

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.

Comparative 1HNMR and UV-Visible Studies of Polyene Polymer Epoxidations Catalyzed by Iron(III), Manganese(III) and Chromium(III) Porphyrins

1998 ◽  
Vol 02 (01) ◽  
pp. 53-60 ◽  
Author(s):  
E. M. DAVORAS ◽  
R. DIAPER ◽  
A. DERVISSI ◽  
M. J. TORNARITIS ◽  
A. G. COUTSOLELOS
Keyword(s):  
Catalytic Activity ◽  
Catalytic Reaction ◽  
Manganese Porphyrin ◽  
Visible Spectroscopy ◽  
Two Phase ◽  
H Nmr ◽  
Catalytic Epoxidation ◽  
Uv Visible ◽  
Phase Systems

The catalytic epoxidation of cis-polybutadiene was studied in two-phase systems, CH 2 CI 2/ H 2 O and PhIO (solid)/ CH 2 Cl 2, using chlorochromium(III), chloromanganese(III) and chloroiron(III) tetraphenylporphyrin complexes as catalysts. Comparison of the catalytic activity of these three catalysts showed that the manganese porphyrin is the most suitable catalyst for this reaction. The results are based on reaction product ratios as determined by 1 H NMR . UV-Visible spectroscopy allowed monitoring of the metalloporphyrin evolution during the catalytic reaction.

ChemInform Abstract: Temperature-programmed Reduction and Catalytic Activity of Ni/Al2O3.

ChemInform ◽  
1987 ◽  
Vol 18 (38) ◽  
Author(s):  
HOANG DANG LANH HOANG DANG LANH ◽  
HO SI THOANG HO SI THOANG ◽  
NGUYEN KHOAI NGUYEN KHOAI ◽  
J. VOELTER
Keyword(s):  
Catalytic Activity ◽  
Temperature Programmed Reduction ◽  
Temperature Programmed

Preparation of Fibrous SO42-/ZrO2-Nio Solid Acid Catalyst, Characterization and its Catalytic Properties

2012 ◽  
Vol 518-523 ◽  
pp. 873-877
Author(s):  
Qiang Du ◽  
Tian Tian Xu ◽  
Xue Mei Song ◽  
Ying Zhang ◽  
Yang Liao ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Solid Acid ◽  
Solid Acid Catalyst ◽  
Acid Catalyst ◽  
Oxide Surface ◽  
Catalyst Characterization ◽  
High Catalytic Activity ◽  
Preparation Conditions ◽  
Acidic Sites ◽  
Temperature Programmed

A novel SO42-/ZrO2-NiO solid acid catalyst was prepared by using collagen fiber as the template. It was found that the SO42-//sup>ZrO2-NiO catalyst remained good fibrous morphology by scanning electron microscopy (SEM). The IR analysis suggested that the metal oxide surface and SO42-were combined to form dual-coordinate state. The catalyst had both medium strong acidic sites and strong acidic sites through temperature-programmed decomposition (TPD) of ammonia. The calcination temperature is inversely proportional to the surface area of fibrous ZrO2-NiO. The catalyst was applied to the esterification of acetic acid with n-butanol to estimate the catalytic activity and the best preparation conditions of SO42-/ZrO2-NiO solid acid catalyst was found out. The results showed the SO42-/ZrO2-NiO catalyst had high catalytic activity.

scholarly journals Zr-Modified ZnO for the Selective Oxidation of Cinnamaldehyde to Benzaldehyde

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 716 ◽  
Author(s):  
Pengju Du ◽  
Tongming Su ◽  
Xuan Luo ◽  
Xinling Xie ◽  
Zuzeng Qin ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Selective Oxidation ◽  
Active Sites ◽  
Catalyst Surface ◽  
Precipitation Method ◽  
N2 Adsorption ◽  
X Ray ◽  
Temperature Programmed ◽  
Zr Modification ◽  
Adsorption Desorption

ZnO and Zr-modified ZnO were prepared using a precipitation method and used for the selective oxidation of cinnamaldehyde to benzaldehyde in the present study. The results showed that physicochemical properties of ZnO were significantly affected by the calcination temperature, and calcination of ZnO at 400 °C demonstrated the optimum catalytic activity for the selective oxidation of cinnamaldehyde to benzaldehyde. With 0.01 g ZnO calcined at 400 °C for 2 h as a catalyst, 8.0 g ethanol and 2.0 g cinnamaldehyde reacted at an oxygen pressure of 1.0 MPa and 70 °C for 60 min, resulting in benzaldehyde selectivity of 69.2% and cinnamaldehyde conversion of 16.1%. Zr was the optimal modifier for ZnO: when Zr-modified ZnO was used as the catalyst, benzaldehyde selectivity reached 86.2%, and cinnamaldehyde conversion was 17.6%. The X-ray diffractometer and N2 adsorption–desorption characterization indicated that doping with Zr could reduce the crystallite size of ZnO (101) and increase the specific surface area of the catalyst, which provided more active sites for the reaction. X-ray photoelectron spectrometer results showed that Zr-doping could exchange the electrons with ZnO and reduce the electron density in the outer layer of Zn, which would further affect benzaldehyde selectivity. The results of CO2 temperature-programmed desorption showed that Zr-modification enhanced the alkalinity of the catalyst surface, which caused the Zr–ZnO catalyst to exhibit higher catalytic activity.

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