Direct Hydrogen Production from Extra-Heavy Crude Oil under Supercritical Water Conditions Using a Catalytic (Ni-Co/Al2O3) Upgrading Process (original) (raw)
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Green Chemistry, 2012
ABSTRACT We report the activity and the selectivity of several heterogeneous nickel catalysts for the supercritical water gasification (SCWG) of biomass. The effects of catalyst support on the carbon conversion and hydrogen selectivity were demonstrated using 44 different materials, covering a wide range of chemical and physical properties. At 5% nickel loading, α-Al2O3, carbon nanotubes (CNTs), and MgO supports resulted in high carbon conversions, while SiO2, Y2O3, hydrotalcite, yttria-stabilized zirconia (YSZ), and TiO2 showed modest activities. Utilization of different γ-Al2O3 supports resulted in a wide range of catalytic activities from almost inactive to highly active. Other catalyst carriers such as zeolites, molecular sieves, CeO2, and ZrO2 had insignificant activity under the conditions tested (i.e., 380 °C, 2 wt% feed). Aside from the catalytic activity, the stable metal oxide supports under the experimental conditions of this work, as identified by XRD, were α-Al2O3, boehmite, YSZ, and TiO2. Given the high hydrogen yield and carbon conversion as well as its superior stability in supercritical water, α-Al2O3 was chosen for a more elaborate investigation. It was found that when using the same amount of nickel, the methane yield significantly decreased by increasing the nickel to support ratio whereas the carbon conversion was only slightly affected. At a given nickel to support ratio, a threefold increase in methane yield was observed by increasing the temperature from 350 to 410 °C. The catalyst activation conditions (e.g., calcination and reduction) had a small impact on its catalytic performance. The catalyst activity increased with the addition of alkali promoters (i.e., K, Na, Cs) and decreased with the addition of tin. The highest catalytic activity was obtained with the addition of 0.5% potassium. In summary, nickel loading and alkali promoters improved the hydrogen selectivity and the carbon conversion of the Ni/α-Al2O3 catalyst.
ASME 2010 8th International Fuel Cell Science, Engineering and Technology Conference: Volume 2, 2010
A series of well crystallized Ni-Co-Zn-Al LDHs materials has been prepared by the urea hydrolysis method as precursors of mixed oxide catalysts for the Ethanol Steam Reforming (ESR) reaction. The calcination of the layered precursors gives rise to high surface area mixed oxides, mainly a mixture of rock-salt phase (NiO), wurtzite phase (ZnO) and spinel phase. Both precursors and mixed oxides have been throughtfully characterized and the steam reforming of ethanol has been investigated over the calcined catalysts in flow reactor and in-situ FT-IR experiments. The data here reported provide evidence of the good catalytic activity of Co-Zn-Al and Co-Ni-Zn-Al catalysts prepared from hydrotalcite-like LHD precursors for ethanol steam reforming. At 823 K the most active Co/Ni catalyst containains a predominant spinel phase with composition near Zn 0.58 Ni 0.42 [Al 0.44 Co 0.56 ] 2 O 4 and small amounts of NiO and ZnO.
2016
In this study, a series of Ni, Co mono and bimetallic catalyst supported by Mg and Al were prepared and evaluated for hydrogen production from various model /waste biomass samples via SCWG process. The SCWG tests were conducted at 650 °C, 26 MPa and water to biomass ratio of five. It was found that for catalyst preparation, coprecipitation technique is better than impregnation, and the best catalyst in terms of hydrogen yield is CopCat-2Ni4Co4. The hydrogen yield from different biomass with this catalyst was found to be in the order of: Canola meal > Timothy grass > Wheat straw ~ Lignin > Cellulose. Canola meal was identified as a promising feedstock for hydrogen production from SCWG. Also, the effect of catalyst loading on hydrogen yield was investigated.It was confirmed that high catalyst loading up to 50 wt% is desirable for hydrogen production.
Topics in Catalysis, 2009
A series of Co-Ni catalysts, prepared from hydrotalcite (HT)-like materials by co-precipitation, has been studied for the hydrogen production by ethanol steam reforming. The total metal loading was fixed at 40% and the Co-Ni composition was varied (40-0, 30-10, 20-20, 10-30 and 0-40). The catalysts were characterized using X-ray diffraction, N 2 physisorption, H 2 chemisorption, temperature-programmed reduction, scanning transmission electron microscope and energy dispersive spectroscopy. The results demonstrated that the particle size and reducibility of the Co-Ni catalysts are influenced by the degree of formation of a HT-like structure, increasing with Co content. All the catalysts were active and stable at 575°C during the course of ethanol steam reforming with a molar ratio of H 2 O:ethanol = 3:1. The activity decreased in the order 30Co-10Ni [ 40Co * 20Ni-20Co * 10Co-30Ni [ 40Ni. The 40Ni catalyst displayed the strongest resistance to deactivation, while all the Co-containing catalysts exhibited much higher activity than the 40Ni catalyst. The hydrogen selectivities were high and similar among the catalysts, the highest yield of hydrogen was found over the 30Co-10Ni catalyst. In general, the best catalytic performance is obtained with the 30Co-10Ni catalyst, in which Co and Ni are intimately mixed and dispersed in the HT-derived support, as indicated by the STEM micrograph and complementary mapping of Co, Ni, Al, Mg and O.
Hydrogenation of CO2 over Alkali Metal-Modified Ni/Al2O3 Catalysts
Adsorption Science & Technology, 1998
A group of Ni and Ni, Li/Al2O3 catalysts were prepared using impregnation and controlled surface reaction methods. The various steps in the preparation were characterised by IR spectroscopy. The catalysts were reduced under the same conditions, while fixed conditions were also employed for the subsequent reactions in order to effect a better comparison. The total and metal surface areas, the degree of nickel reduction and the activity of the catalysts towards CO2 methanation were all measured in order to compare the effect of preparation method on the structural properties as well as on the catalyst activity and selectivity. Nickel catalysts modified with lithium, either by controlled surface reaction or double impregnation utilising H2Li2EDTA, exhibited a higher activity in CO2 methanation than any other catalyst samples investigated.
Renewable hydrogen production via steam reforming of simulated bio-oil over Ni-based catalysts
International Journal of Hydrogen Energy, 2019
The production of hydrogen via steam reforming (SR) of simulated bio-oil (glycerol, syringol, n-butanol, m-xylene, m-cresol, and furfural) was investigated over Ni/CeO 2-Al 2 O 3 and Me-Ni/CeO 2-Al 2 O 3 (Me ¼ Rh, Ru) catalysts. Monometallic (Ni) and bimetallic (Rh-Ni and Ru-Ni) catalysts were prepared by the wetness impregnation technique of the CeO 2-Al 2 O 3 support previously synthesized by the surfactant-assisted co-precipitation method. The as-prepared powders were systematically characterized by N 2-physisorption, XRD, H 2-TPR, and TEM measurements to analyze their structure, morphology, and reducibility properties. Experiments were performed in a continuous fixed-bed reactor at atmospheric pressure, temperature of 800 C, steam to carbon (S/C) ratio of 5, and WHSV of 21.15 h À1. Then, the temperature was decreased to 700 C and increased afterwards to 800 C. After the experiments TPO and TEM analysis were performed on the spent catalysts to check any evidence of catalyst deactivation. The results showed that the incorporation of noble metal (Ru or Rh) promoter positively affected the activity of the Ni/CeO 2-Al 2 O 3 catalysts by enhancing the reducibility of Ni 2þ species. Ni-based catalyst deactivated under the studied conditions, whereas Ru-and mainly Rh-promoted systems showed increased resistance to carbon deposition by favouring the gasification of adsorbed carbon species. Between all tested catalysts, the Rh-Ni/CeO 2-Al 2 O 3 provided the highest H 2 yield and coking-resistance in SR of simulated bio-oil.
Steam reforming of sunflower oil over Ni/Al catalysts prepared from hydrotalcite-like materials
2003
Using catalytic steam reforming of biofuels to produce hydrogen for energy systems based on fuel cells is an option that may help to reduce the net emissions of CO 2 into the atmosphere. Vegetable oils are some of the most interesting options because of their high potential yield of hydrogen. They are, however, more difficult to reform than the light hydrocarbon feedstocks that are used for producing hydrogen industrially by steam reforming. Catalysts prepared from hydrotalcite-like materials are promising for use in the steam reforming of vegetable oils, since their catalytic activity is significantly higher than that of commercial catalysts for hydrocarbon steam reforming. In this paper, a study is made of how the nickel content of HT-derived catalysts affects their activity for steam reforming of sunflower oil. Three catalysts were prepared with Ni/Al atomic ratios of 1, 2, and 3, respectively. The samples were characterized by various techniques to correlate their activity with the structural characteristics of the catalysts: X-ray diffraction (XRD), BET, thermogravimetric analysis (TGA), and hydrogen chemisorption. The results showed that the catalyst activity increased as the nickel content in the material decreased. The support and its properties seemed to play a key role in the performance of the HT-derived catalysts. This is probably because a decrease in the Ni content produces a better dispersion of the metal and higher BET areas, which leads to a higher capacity for water adsorption. With the most active catalyst (Ni/Al of 1), 2.2 mol H 2 /(g cat h) was produced at 575 8C, 2 bar, and a steam-to-carbon ratio of 3.
Catalysis Communications, 2001
Steam reforming vegetable oils has recently been proposed as a process for producing hydrogen from renewable resources. In this paper, we present a hydrotalcite-type (HT) nickel catalyst, with an Ni/Al atomic ratio of 2/1, that is suitable for steam reforming sun¯ower oil. We have studied the activity of this catalyst at steam to carbon (S/C) ratios of 3, 6 and 9, and temperatures from 500°C to 650°C, and compared it with two commercial catalysts for steam reforming hydrocarbons (ICI 46/1 and UCI G90C). The HT catalyst had almost 10 times more catalytic activity than the commercial catalysts. Structural characterization of the catalysts by BET, X-ray diraction (XRD) and hydrogen-pulse chemisorption, showed that the higher activity of the HT catalyst is due to its higher surface and metal areas. These are 104 and 17:2 m 2 =g, respectively.
Journal of Natural Gas Science and Engineering, 2011
Cobalt nickel oxide catalysts, prepared using co-precipitation procedure, were studied for the conversion of synthesis gas to light olefins. Specially, we studied the effect of a range of preparation variables, including the molar ratio of the [Co]/[Ni], pH, temperature and ageing time of the precipitation solution and finally, calcination conditions such as calcination temperature and calcination time. The catalyst containing a molar ratio of 80% Co and 20% Ni, aged for 150 min, precipitated at 50 C and pH of 8.3 and calcined at 550 C for 10 h performed optimally for the conversion of synthesis gas to light olefins. Characterization of both precursors and calcined catalysts was carried out using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) specific surface area measurements and thermal analysis methods including Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC).