Samarium Promoted Ni/Al2O3 Catalysts for Syngas Production from Glycerol Pyrolys (original) (raw)
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Syngas production from glycerol-dry(CO2) reforming over La-promoted Ni/Al2O3 catalyst
Renewable Energy, 2015
A 3 wt% La-promoted Ni/Al2O3 catalyst was prepared via wet co-impregnation technique and physicochemically-characterized. Lanthanum was responsible for better metal dispersion; hence higher BET specific surface area (96.0 m2 g−1) as compared to the unpromoted Ni/Al2O3 catalyst (85.0 m2 g−1). In addition, the La-promoted catalyst possessed finer crystallite size (9.1 nm) whilst the unpromoted catalyst measured 12.8 nm. Subsequently, glycerol dry reforming was performed at atmospheric pressure and temperatures ranging from 923 to 1123 K employing CO2-to-glycerol ratio from zero to five. Significantly, the reaction results have yielded syngas as main gaseous products with H2:CO ratios always below than 2.0 with concomitant maximum 96% glycerol conversion obtained at the CO2-to-glycerol ratio of 1.67. In addition, the glycerol consumption rate can be adequately captured using power law modelling with the order of reactions equal 0.72 and 0.14 with respect to glycerol and CO2 whilst the activation energy was 35.0 kJ mol−1. A 72 h longevity run moreover revealed that the catalyst gave a stable catalytic performance.
Bulletin of Chemical Reaction Engineering & Catalysis, 2016
The carbon dioxide (CO2) dry reforming of glycerol for syngas production is one of the promising ways to benefit the oversupply crisis of glycerol worldwide. It is an attractive process as it converts carbon dioxide, a greenhouse gas into a synthesis gas and simultaneously removed from the carbon biosphere cycle. In this study, the glycerol dry reforming was carried out using Silver (Ag) promoted Nickel (Ni) based catalysts supported on silicon oxide (SiO2) i.e. Ag-Ni/SiO2. The catalysts were prepared through wet impregnation method and characterized by using Brunauer-Emmett-Teller (BET) surface area, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Thermo Gravimetric (TGA) analysis. The experiment was conducted in a tubular reactor which condition fixed at 973 K and CO2:glycerol molar ratio of 1, under atmospheric pressure. It was found that the main gaseous products are H₂, CO and CH4 with H₂:CO molar ratio < 1.0. From the reaction study, Ag(5)-Ni/SiO2 results i...
Conversion of glycerol over 10%Ni/γ-Al2O3 catalyst
Applied Catalysis B: Environmental, 2014
The conversion of glycerol in gas phase and atmospheric pressure has been investigated over 10 wt.% Ni/␥-Al 2 O 3 catalyst. The catalysts were prepared with nickel nitrate and pre-treated with hydrogen in the range of 623-1073 K. The resultant catalysts were characterized by N 2-physisoption, H 2-chemisorption, X-ray diffraction (XRD), TGA-MS, TEM, RAMAN, NH 3-TPD, XPS, TPO-MS and XANES. The stability and the catalytic behavior of the catalysts were affected by the reduction pre-treatment. Glycerol reaction pathways were proposed based on dehydration, dehydrogenation and hydrogenolysis steps. The main products identified were: hydroxyacetone, pyruvaldehyde, pyruvic acid, lactic acid, lactide, acetaldehyde and methane. The number of exposed Ni atoms and the degree of reduction of the NiO species affected the hydrogenolysis reaction of glycerol to CH 4 affecting the catalytic stability. The catalyst was deactivated by coke formation, by transformation of Ni phase to nickel carbide (Ni 3 C), as well as by oxidation of the Ni phase during the reaction. In addition, Raman analysis revealed two types of carbonaceous deposits over the used samples: on the Ni species and on the support. The regeneration treatment by oxidation-reduction reactivated the catalyst successfully.
Hydrogen production via glycerol dry reforming over La-Ni/Al 2O3 catalyst
2013
Glycerol (a bio-waste generated from biodiesel production) has been touted as a promising bio-syngas precursor via reforming route. Previous studies have indicated that carbon deposition is the major performance-limiting factor for nickel (Ni) catalyst during glycerol steam reforming. In the current paper, dry (CO2)-reforming of glycerol, a new reforming route was carried out over alumina (Al2O3)-supported nonpromoted and lanthanum-promoted Ni catalysts. Both sets of catalysts were synthesized via wet coimpregnation procedure. The physicochemical characterization of the catalyst showed that the promoted catalyst possessed smaller metal crystallite size, hence higher metal dispersion compared to the virgin Ni/Al2O3 catalyst. This was also corroborated by the surface images captured by the FESEM analysis. In addition, BET surface area measurement gave 92.05m²/g for non-promoted Ni catalyst whilst promoted catalysts showed an average of 1 to 6% improvement depending on the La loading. Reaction studies at 873 K showed that glycerol dry reforming successfully produced H2 with glycerol conversion and H2 yield that peaked at 9.7% and 25% respectively over 2wt% La content. The optimum catalytic performance by 2%La-Ni/Al2O3 can be attributed to the larger BET surface area and smaller crystallite size that ensured accessibility of active catalytic area.
2021
Received: 2nd June June 2021 Revised: 29th July 2021 Accepted: 26th August 2021 Online: 31 August 2021 The aqueous phase reforming (APR) of glycerol into value-added products, including H2 and alkanes, is environmentally green. In this work, the conversion of glycerol into syngas was demonstrated using MgO-supported Ni-Sn catalysts. Ni species is known for its capability of converting glycerol, but the activity towards water gas shift (WGS) reaction has not been satisfied. Loading Ni-Sn onto MgO has increased the catalyst basicity, which promotes a positive effect in WGS reaction. A series of bimetallic catalysts, impregnated Ni-Sn on MgO support, was prepared with various Ni-Sn loading amounts. To better understand the behavior of prepared catalysts, they were evaluated physiochemically through XRD, BET, and FTIR. The catalytic activity test was performed for APR in a continuous flow reactor with aqueous glycerol 10 v-% as a feedstock at a reaction temperature of 250°C. As a result...
Experimental Investigation of Steam Reforming of Glycerol over Alumina Supported Nickel Catalysts
The growing demand of hydrogen needs renewable sources of raw materials to produce it. Glycerol, by-product of biodiesel synthesis, could be a bio-renewable substrate to obtain hydrogen. Momentous amount of glycerol is produced as a byproduct during bio-diesel production by the transesterification of vegetable oils, which are available at low cost in large supply from renewable raw materials. As hydrogen is a clean energy carrier, conversion of glycerol to hydrogen is one among the most attractive ways to make use of glycerol. Production of hydrogen from glycerol is environmentally friendly because it adds value to glycerol generated from biodiesel plants. In this study, the catalytic production of hydrogen by steam reforming of glycerol has been experimentally performed in a fixed-bed reactor. The performance of this process was evaluated over 5wt%, 10wt%, and 15wt% Ni/Al2O3. The catalysts were prepared by the wet impregnation technique. For a comparative purpose, the steam reforming experiments were conducted under same operating conditions, i.e., reaction temperature ranging from 700°C to 900°C, atmospheric pressure and 1:9 glycerol to water molar ratio. Also the effect of glycerol to water ratio, metal loading, and the feed flow rate (space velocity) was analysed. The results showed that the hydrogen production increased with the increase in the treatment temperature. The highest amount of hydrogen produced was attained over 15wt% Ni/Al2O3 at 850 °C at 1:9 glycerol to water molar ratio. The catalyst Co/Al2O3,Cu/Al2O3 were prepared by wet impregnation technique and need to do activity test and compare the results with Ni/Al2O3.
Nickel Catalysts Supported Over TiO 2 , SiO 2 and ZrO 2 for the Steam Reforming of Glycerol
ChemCatChem, 2012
The main reaction route is parallel to coking by CO decomposition and dehydration of the substrate to form surface olefin species, which may desorb, reformate or, regrettably, polymerise to form carbonaceous deposits. [6] This is especially the case if a low water/glycerol feeding ratio is employed. Coke may also form as a result of the Bouduard reaction (CO disproportion), which may be thermodynamically favoured below 700 8C. [7] Coke removal is possible by steaming and gasification, particularly at high temperature. [2, 8] Detailed investigations into catalyst deactivation are available for methane or ethanol SR. The dehydration reaction pathway is mainly favoured by big Ni particles, [9, 10] but also by strong surface acidity (e.g. in the case of Al 2 O 3 supported samples). Considerable efforts have been devoted to develop nonacidic supports, such as MgAl 2 O 4 , [2, 11] Ni x Mg 1Àx O [12] or MgO. [13, 14] Up until now, these have mainly been adopted for the SR of ethanol. Unfortunately, such catalysts either showed unsatisfactory activity or, even when active, induced some scale-up problems owing to poor mechanical properties or formation problems. Alternatively, attempts have been made to limit surface acidity of common supports, for example, by impregnating alumina or zirconia with lanthanum oxide. [6, 15] The best catalytic systems appear to be the ones in which the synergism between the metal and the support leads to metal stabilisation and decreases the rate of coke formation. MgO, CeO 2 and TiO 2 were used for their well-known ability to retard coke formation and to interact with metals that promote the catalytic activity as supports. [16, 17] Furthermore, the modification of Ni/Al 2 O 3 with Ce, Zr, Mg and La, brought about an improvement in hydrogen selectivity owing to surface Ni exposure in the case of Mg, steam activation for Zr, and stability of the metallic phase under the reaction conditions if Ce or La were added. [18] Nevertheless, in spite of a growing number of papers on GSR, activity data are often contrasting and no clear relationships between the main physicochemical properties of the catalyst and its activity, selectivity and durability have been drawn. Therefore, the aim of this work was to design, synthesise and characterise supported Ni catalysts for GSR. TiO 2 , SiO 2 , mesoporous SBA-15 and ZrO 2 were chosen as supports owing to their different acidic and redox properties, and interaction with the metallic active phase. The catalysts were prepared by using different synthetic procedures, which were able to tune the thermal resistance and Ni dispersion. In particular, each sample was synthesised from the liquid phase, with the active phase deposited by impregnation, and calcined at 800 8C to impart proper thermal resistance for this high temperature application. In addition, a special preparation procedure, namely flame pyrolysis (FP) was employed to achieve high temperature stability and high metal dispersion. The latter technique proved effective for the preparation of thermally resistant samples for different high-temperature applications, such as the catalytic combustion of methane. [19, 20] Furthermore, it led to unexpectedly high dispersion of the active phase in differently supported V-based catalysts even at relatively high loading (up to 10 wt %). [21, 24] Therefore, it seems in
RSC Advances, 2014
Glycerol steam reforming, which is a potential technology for hydrogen production in fuel-cell applications, is of great interest to researchers in recent years. Using aqueous glycerol, which is a byproduct in biodiesel production, as a direct feed for steam reforming is a promising method to produce hydrogen. Ni (5, 10, 15, 20 and 25 wt%) loaded on commercial γ-Al2O3 by the impregnation method is used to study steam reforming of glycerol. The catalyst was characterized by XRD, EDAX, BET surface area, TPR, NH3-TPD, TEM, CHNS and Raman techniques. The catalysts are evaluated on time streams for the effect of Ni loading, temperature, and glycerol-to-water mole ratio (GWMRs). Under the parameters investigated, 15 wt% Ni/γ-Al2O3 was found to be the most promising catalyst in terms of glycerol conversion and hydrogen production with minimum coking. The characterization of the catalysts clearly establishes that interaction of Ni2+ with γ-Al2O3 support, Ni2+ reducibility, particle size, and acidity of the support are seen governing the stable activity of the catalysts. Thus, a structural activity correlation has been established on the Ni/γ-Al2O3 catalysts.
CO2 reforming of coke oven gas over a Ni/γAl2O3 catalyst to produce syngas for methanol synthesis
Fuel, 2012
The CO 2 reforming of coke oven gases (COG) was carried out over a Ni/γAl 2 O 3 catalyst in order to obtain a suitable syngas for methanol synthesis. The influence of different operating conditions, such as temperature and volumetric hourly space velocity (VHSV), was studied. It was found that the H 2 present in the feed gas promotes the Reverse Water Gas Shift reaction (RWGS), which produces water. Nevertheless, the Ni/γAl 2 O 3 catalyst showed a high selectivity to the CO 2 reforming reaction and it was possible to avoid the RWGS under certain operating conditions. Moreover, a part of the reaction could take place via a different path (RWGS followed by the steam reforming of methane instead of the direct dry reforming of methane). The deactivation of the Ni/γAl 2 O 3 catalyst was also studied. Both the methane and the carbon dioxide conversions remained steady for 50 hours without showing any sign of deactivation.
Catalytic performance of Ni-Cu/Al 2 O 3 for effective syngas production by methanol steam reforming
Fuel
Publisher: Elsevier NOTICE: this is the author's version of a work that was accepted for publication in Fuel. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Fuel, [232], (2018)]