In this work, monometallic (1 wt% of Ru or 5 wt% of Ni) and bimetallic catalysts (1 wt% Ru-5 wt.% Ni) deposited on alumina (Al2O3), magnesium aluminate spinel (MgAl2O4), and yttria-stabilized ...zirconia (YSZ) were prepared by wet impregnation. The synthesis method of MgAl2O4 was optimized and a well crystallized phase with high specific surface area was obtained by using wet impregnation, as a simple and low cost route, at 800 °C for 2 h.
The catalytic activity was compared at atmospheric pressure and 750 °C toward methane dry reforming (DRM) reaction with a molar ratio CH4/CO2 = 1/1 and a Weight Hourly Space Velocity (WHSV) of 60.000 mL g−1.h−1.
Catalytic activity classification was obtained as the following: Ni/MgAl2O4 > Ru-Ni/Al2O3 > Ru-Ni/MgAl2O4 > Ru-Ni/YSZ > Ni/Al2O3 > Ni/YSZ > Ru/Al2O3 > Ru/YSZ » Ru/MgAl2O4. Between the different catalysts, 5 wt% Ni/MgAl2O4 catalyst exhibited excellent catalytic activity for DRM. Furthermore, this catalyst was found to be very stable without any deactivation after 50 h under reacting mixture with a low carbon formation rate (3.58 mgC/gcat/h). Such superior activity and stability of MgAl2O4 supported Ni catalyst is consistent with characterization results from BET, XRD, TPR, CO-pulse chemisorption and CHNS analysis. It can be due to a strong interaction between Ni and MgAl2O4 leading to the incorporation of Ni into the spinel lattice and the formation of oxygen vacancies offering a benefit for DRM reaction.
Furthermore, it seems that the addition of ruthenium onto Ni/MgAl2O4 decreases the interaction between Ni and the spinel leading to a decrease in the catalyst performance. On the other side, the addition of ruthenium on Ni/Al2O3 leads to an increase in the catalyst stability and efficiency by inhibiting the formation of poorly active phase NiAl2O4 already observed in TPR.
•5 wt% Ni/MgAl2O4 exhibits highest performance in DRM.•Strong Ni/MgAl2O4 interaction leads to incorporation of Ni into spinel lattice.•Ru addition has positive effect on Ni/Al2O3for DRM contrary to Ni/MgAl2O4 and Ni/YSZ.•5 wt% Ni/MgAl2O4: high stability without deactivation after 50 h in reacting mixture.
The aim of this work was to determine the nature and the strength of surface acid sites present on boron alumina surface. From the results obtained by FTIR of CO adsorbed at −135 °C, it can be ...concluded that the boron alumina has a Brönsted acidity due to the OH groups. These Brönsted acid sites are stronger than those of γ-alumina but in much smaller quantities due to its lower specific surface area. Similarly, it is noted that the boron alumina exhibits a single OH type with a single band around 3701 cm
−1
. This band represents a single configuration of OH species linked to boron and this species is disturbed by the adsorption of the CO probe molecule whereas on alumina we notice the presence of four OH species linked to aluminum. Only one of which is disturbed by the adsorption of CO with a decrease in the intensity of this band and the increase in the intensity of a band present at lower frequency.
This work consists in the study of catalysts likely to present a good activity in the combustion of the landfill biogas for its valorization and a high performance in the selective catalytic ...oxidation of NH
3
to N
2
. In this study, biogas catalytic combustion was investigated on 2 wt%PdO/5 wt%CuO/γ-Al
2
O
3
catalyst. This catalyst was prepared by wet impregnation than the catalytic reactivity was tested under atmospheric pressure using the following mixture: CH
4
(1 vol%), CO
2
(0.6 vol%), O
2
(4 vol%), H
2
O (0.1 vol%), 1000 ppm NH
3
and He with a total flow rate of 100 cm
3
min
−1
and compared with 2 wt%PdO/Al
2
O
3
and 5 wt%CuO/Al
2
O
3
. Furthermore, these different catalysts were characterized by inductively coupled plasma atomic emission spectroscopy, specific surface area analysis (BET), X-ray diffraction, diffuse reflectance spectroscopy and H
2
temperature-programmed reduction (H
2
-TPR). This study showed that 2 wt%PdO/5 wt%CuO/γ-Al
2
O
3
catalyst exhibited a better performance towards the selective catalytic oxidation of NH
3
into N
2
compared to the other catalysts with a methane conversion corresponding to the best compromise in between.
Hydrogen production from dry reforming of methane (DRM) was investigated on different Nickel based catalysts deposited on MgAl2O4. MgAl2O4 spinel was prepared using γ-Alumina supplied from different ...manufacturers (Sigma Aldrich, Alfa Aesar and Degussa) with low and high specific surface area. Moreover, the influence of different parameters on the catalytic activity on methane dry reforming was studied such as the effect of Ni content, the effect of commercial alumina and the effect of doping nickel with cerium and lanthanum.
During this study, the catalytic activity was compared at atmospheric pressure at 750 °C during 4 h then 650 °C during 4 h toward methane dry reforming (DRM) reaction with a molar ratio CH4/CO2 = 1/1 and a Weight Hourly Space Velocity (WHSV) of 60.000 mL g−1.h−1. The results showed that among the different catalysts 1.5Ce–Ni5/MgAl2O4, synthesized with alumina from Alfa Aesar, exhibited the best catalytic activity for DRM.
Furthermore, this catalyst showed the best performance during a stability test at 600 °C for 24 h under reacting mixture with a low carbon formation rate (2.71 mgC/gcat/h). Such superior activity is consistent with characterization results from BET, XRD, SEM, TPR and TPO analysis. Furthermore, it seems that the addition of Cerium on Ni/MgAl2O4 leads to an increase in catalyst efficiency. It can be due to an effective active oxygen transfer due to the redox properties of CeO2, leading to the formation of oxygen vacancies offering a benefit for DRM reaction.
•5 wt.% Ni can be used as optimal concentration in order to obtain high performance.•Between Ce and La promoters, Ce addition has positive effect on Ni/MgAl2O4 for DRM.•1.5Ce-Ni5/MgAl2O4 exhibits highest performance in DRM.
Abstract Isopropyl alcohol (IPA) catalytic oxidation remains one of the most popular techniques to remove volatile organic compounds from indoor places. In our study, catalytic oxidation of IPA was ...investigated on catalysts based on platinum deposited on mullite (Al6Si2O13), known for its excellent thermal stability. Pt/Al6Si2O13 catalysts were prepared by impregnation with and without methyl cellulose (MC) and were tested in order to study the influence of MC on the platinum particle dispersion over the support. The catalytic reactivity was compared with Pt/α-alumina and Pt/SiO2. Moreover, the resulting materials were characterized by BET, XRD, TEM and H2-chemisorption. This study showed that platinum exhibits better dispersion on alumina sites than silica sites. This can be due to a strong interaction between platinum and alumina, leading to a higher dispersion of platinum species. Furthermore, the addition of MC enhanced the Pt dispersion over the mullite, leading to an improvement in the catalytic performance.
Well crystallised aluminium borate Al
18B
4O
33 has been synthesised from alumina and boric acid with a BET area of 18
m
2/g after calcination at 1100
°C. Afterwards, 2
wt.% Pd/Al
18B
4O
33 was ...prepared by conventional impregnation of Pd(NO
3)
2 aqueous solution and calcination in air at 500
°C. The catalytic activity of Pd/Al
18B
4O
33 in the complete oxidation of methane was measured between 300 and 900
°C and compared with that of Pd/Al
2O
3. Pd/Al
18B
4O
33 exhibited a much lower activity than Pd/Al
2O
3 when treated in hydrogen at 500
°C or aged in O
2/H
2O (90:10) at 800
°C prior to catalytic testing. Surprisingly, a catalytic reaction run up to 900
°C in the reaction mixture induced a steep increase of the catalytic activity of Pd/Al
18B
4O
33 which became as active as Pd/Al
2O
3. Moreover, the decrease of the catalytic activity observed around 750
°C for Pd/Al
2O
3 and attributed to PdO decomposition into metallic Pd was significantly shifted to higher temperatures (820
°C) in the case of Pd/Al
18B
4O
33. The existence of two distinct types of PdO species formed on Al
18B
4O
33 and being, respectively, responsible for the improvement of the activity at low and high temperature was proposed on the basis of diffuse reflectance spectroscopy and temperature-programmed desorption of O
2.
We present a unique meteorological and snow observational dataset in Mount Lebanon, a mountainous region with a Mediterranean climate, where snowmelt is an essential water resource. The study region ...covers the recharge area of three karstic river basins (total area of 1092 km2 and an elevation up to 3088 m). The dataset consists of (1) continuous meteorological and snow height observations, (2) snowpack field measurements, and (3) medium-resolution satellite snow cover data. The continuous meteorological measurements at three automatic weather stations (MZA, 2296 m; LAQ, 1840 m; and CED, 2834 m a.s.l.) include surface air temperature and humidity, precipitation, wind speed and direction, incoming and reflected shortwave irradiance, and snow height, at 30 min intervals for the snow seasons (November–June) between 2011 and 2016 for MZA and between 2014 and 2016 for CED and LAQ. Precipitation data were filtered and corrected for Geonor undercatch. Observations of snow height (HS), snow water equivalent, and snow density were collected at 30 snow courses located at elevations between 1300 and 2900 m a.s.l. during the two snow seasons of 2014–2016 with an average revisit time of 11 days. Daily gap-free snow cover extent (SCA) and snow cover duration (SCD) maps derived from MODIS snow products are provided for the same period (2011–2016). We used the dataset to characterize mean snow height, snow water equivalent (SWE), and density for the first time in Mount Lebanon. Snow seasonal variability was characterized with high HS and SWE variance and a relatively high snow density mean equal to 467 kg m−3. We find that the relationship between snow depth and snow density is specific to the Mediterranean climate. The current model explained 34 % of the variability in the entire dataset (all regions between 1300 and 2900 m a.s.l.) and 62 % for high mountain regions (elevation 2200–2900 m a.s.l.). The dataset is suitable for the investigation of snow dynamics and for the forcing and validation of energy balance models. Therefore, this dataset bears the potential to greatly improve the quantification of snowmelt and mountain hydrometeorological processes in this data-scarce region of the eastern Mediterranean. The DOI for the data is https://doi.org/10.5281/zenodo.583733.
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