The Influence of Lanthanide on NiO-MgO-SiO2 Catalysts for Syngas Production via Propane Steam Reforming (original) (raw)
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Catalysts
The oxy-steam reforming of liquefied natural gas reaction (OSR-LNG) is promising process for syngas generation. In this paper, the catalytic properties of NiO/La2O3 systems prepared by wet impregnation and co-precipitation methods were extensively investigated in OSR-LNG reaction. The physicochemical properties of the studied catalytic materials were determined using various techniques including Temperature programmed reduction (TPR-H2), Temperature programmed desorption (TPD-NH3), Brunauer, Emmett and Teller (BET), X-ray diffraction (XRD) and Scanning electron microscopy (SEM) with an energy dispersive X-Ray spectrometer (EDS). Reactivity measurements performed in the OSR-LNG process showed that the catalyst preparation method and the calcination temperature significantly affected the activity of NiO/La2O3 catalysts in the OSR-LNG reaction. The catalytic activity tests showed that NiO/La2O3 system prepared by a wet impregnation method and calcined at 700 °C showed the total convers...
Role of La2O3 as Promoter and Support in Ni/γ-Al2O3 Catalysts for Dry Reforming of Methane
Chinese Journal of Chemical Engineering, 2014
The nature of support and type of active metal affect catalytic performance. In this work, the effect of using La 2 O 3 as promoter and support for Ni/γ-Al 2 O 3 catalysts in dry reforming of methane was investigated. The reforming reactions were carried out at atmospheric pressure in the temperature range of 500-700 °C. The activity and stability of the catalyst, carbon formation, and syngas (H 2 /CO) ratio were determined. Various techniques were applied for characterization of both fresh and used catalysts. Addition of La 2 O 3 to the catalyst matrix improved the dispersion of Ni and adsorption of CO 2 , thus its activity and stability enhanced.
An Alumina-Supported Ni-La-Based Catalyst for Producing Synthetic Natural Gas
Catalysts, 2016
LaNi 5 , known for its hydrogen storage capability, was adapted to the form of a metal oxide-supported (γ-Al 2 O 3) catalyst and its performance for the Sabatier reaction assessed. The 20 wt % La-Ni/γ-Al 2 O 3 particles were prepared via solution combustion synthesis (SCS) and exhibited good catalytic activity, achieving a CO 2 conversion of 75% with a high CH 4 selectivity (98%) at 1 atm and 300 • C. Characteristics of the La-Ni/γ-Al 2 O 3 catalyst were identified at various stages of the catalytic process (as-prepared, activated, and post-reaction) and in-situ DRIFTS was used to probe the reaction mechanism. The as-prepared catalyst contained amorphous surface La-Ni spinels with particle sizes <6 nm. The reduction process altered the catalyst make-up where, despite the reducing conditions, Ni 2+-based particles with diameters between 4 and 20 nm decorated with LaO x moieties were produced. However, the post-reaction catalyst had particle sizes of 4-9 nm and comprised metallic Ni, with the LaO x decoration reverting to a form akin to the as-prepared catalyst. DRIFTS analysis indicated that formates and adsorbed CO species were present on the catalyst surface during the reaction, implying the reaction proceeded via a H 2-assisted and sequential CO 2 dissociation to C and O. These were then rapidly hydrogenated into CH 4 and H 2 O.
Journal of Catalysis, 1997
The reforming of methane by carbon dioxide is studied over a Ni/La 2 O 3 catalyst which presents an unusual catalytic stability compared to other nickel-based catalysts. A thorough TEM/EDX study combined with isotopic transient DRIFT and TAP experiments reveals the existence of a tight interface between a lanthanum carbonate phase and the nickel particles. A "bi-functional" mechanism is proposed to account for the observed kinetic behaviour: methane is activated on the Ni particles, carbon dioxide interacts with La 2 O 3 to form carbonates which scavenge carbon from nickel at the Ni-La 2 O 3 interface, thus restoring the Ni particles to their original state. This specific morphology of the active phase is also assumed to hinder the formation of deactivating coke, which explains the catalytic stability of such a catalyst.
The catalytic performance of Ce-and La-promoted Ni/SBA-15 catalysts for syngas production from CO2 reforming of methane has been investigated in a fixed-bed reactor at stoichiometric feed composition. Both promoted and unpromoted catalysts possessed high BET surface area of 303-445 m 2 g-1. Additionally, SBA-15 support had a relatively uniform rod-like shape with a diameter of about 0.55 µm and a reduction in the crystallite size of NiO phase from 27.0 to 19.1 nm was observed with promoter addition reasonably due to the strong interaction between promoter and NiO particles. CeO2 and La2O3 dopants were finely dispersed on catalyst surface. Temperature-programmed oxidation of spent catalysts showed that coke-resistance was improved significantly with promoter modification and 3%La-10%Ni/SBA-15 catalyst was the most resistant to carbonaceous deposition rationally due to the least NiO crystallite size hindering the nucleation and growth of graphitic carbon. Hence, La-promoted catalyst appeared to be the optimum catalyst in terms of reactant conversion, H2 yield and stability whilst a gradual decline in both reactant conversion and H2 yield was experienced with unpromoted and Ce-doped catalysts. Regardless of catalyst types, the ratio of H2 to CO was always less than unity preferred for Fischer-Tropsch synthesis.
Industrial & Engineering Chemistry Research, 2019
Deactivation of Ni/La 2 O 3 2 O 3 catalyst in the ethanol steam reforming (ESR) was studied in order to establish the optimal conditions for maximizing H 2 production and achieving steady behavior. The ESR reactions were conducted in a fluidized bed reactor under the following operating conditions: 500-650 ºC; space-time up to 0.35 g catalyst h/g EtOH ; and steam/ethanol (S/E) molar ratio in the feed, 3-9. The features of the deactivated catalysts and the nature and morphology of the coke deposited were analyzed by Temperature Programmed Oxidation, X-Ray Diffraction, Scanning Electron Microscopy, and Raman Spectroscopy. Catalyst deactivation was solely caused by coke deposition, especially by encapsulating coke, with acetaldehyde, ethylene, and ethanol being the main precursors, whose concentration was high for lower values of space-time. Conversely, the filamentous coke formed from CH 4 and CO (with their highest concentration for intermediate values of space-time) had a much lower impact on deactivation. Owing to the effect of space-time on the extent of reactions leading to the formation of coke precursors, the Ni/La 2 O 3 2 O 3 catalyst stability was enhanced by increasing space-time. The increase in temperature and S/E ratio was also beneficial since both variables promoted coke gasification. Consequently, a steady H 2 yield throughout 200 h reaction was attained at 600 ºC, the space-time of 0.35 g catalyst h/g EtOH and S/E > 3.
Bulletin of Chemical Reaction Engineering & Catalysis
In this paper, the catalytic properties of La-Ni-M (M = Co, Cu) based materials in dry reforming of methane (DRM) for syngas (CO + H2) production, were studied in the temperature range 773−1073 K. The LaNi0.9M0.1O3 and La2Ni0.9M0.1O4 (M = Co, Cu and Ni/M = 0.9/0.1) catalysts were prepared by partial substitution of Ni by Co or Cu using sol-gel method then characterized by XRD, H2-TPR and N2 physisorption. The XRD analysis of fresh catalysts showed, in the case of Co-substitution, the formation of La-Ni and La-Co perovskite and spinel structures, while only LaNiO3 and La2NiO4 phases were observed for the Cu-substituted samples. The substitution of these two structures by copper decreases the reduction temperature compared to cobalt. The reactivity results showed that the partial substitution of nickel by copper decreases the methane activation temperature, whereas a better stability of catalytic activity and syngas production was obtained via the cobalt-substituted catalysts, which i...
Analysis of Ni/La2O3–αAl2O3 Catalyst Deactivation by Coke Deposition in the Ethanol Steam Reforming
The effect of C-containing byproducts on the deactivation of Ni/La 2 O 3 -αAl 2 O 3 catalyst in the steam reforming of ethanol (SRE) was studied. The catalyst was prepared by wet impregnation method and subsequently calcined at 550ºC and reduced at 700ºC, prior the reforming reactions. The kinetic runs were carried out in a fluidized bed reactor under the following operating conditions: atmospheric pressure; 500 ºC; space-time, 5.2 and 9.2 g catalyst min g EtOH -1 and time on stream, 20 h. The properties of the fresh and used catalysts were analyzed by N 2 adsorption-desorption, H 2 chemisorption and X-ray diffraction (XRD), and the nature and amount of coke deposited on the catalyst were analyzed by Scanning Electron Microscopy (SEM) and Temperature Programmed Oxidation (TPO) analysis. It was found that the catalyst deactivation level is not directly dependent on the coke content but it highly depends on ethanol conversion: for a low conversion, the coke deposited encapsulates and blocks the metallic active sites, causing a fast deactivation of the catalyst, whereas for a high conversion the coke is deposited as filamentous carbon that contributes to decreasing the catalyst porosity but without affecting notably to catalyst stability. The different nature of the coke deposited on the catalyst is attributed to the intermediate compounds produced in the reaction medium, with acetaldehyde being the major responsible for the formation of encapsulating coke, whereas the CH4 and CO presence favors the formation of fibrous coke.
Hydrogen production from a mixture of side products of pyrolysis oil through the catalytic steam reforming was carried out. Acetic acid and phenol were considered as side products in the bio-oil derived from the pyrolysis of biomass. The performance of bimetallic Nickel-Cobalt (Ni-Co) catalyst supported on different ratios of Lanthanum (III) Oxide (La 2 O 3) and gamma-aluminum oxide (g-Al 2 O 3) was evaluated. The catalytic properties of the prepared catalysts were characterized for the total acidity, basicity, catalyst total surface area, crystallinity and the reducibility of active metal. The results of the characterization shows that presence of g-Al 2 O 3 as a support decreased the reducibility, acidic and basic site of the catalyst but increased its performance due to high surface area. By increasing the g-Al 2 O 3 metal oxide content in the catalyst, the coke deposits are increased because of the weak interaction of metal-support of high g-Al 2 O 3 contents catalysts. Catalyst dilution was found to increase the performance of the steam reforming reaction by changing the catalyst bed height. The results show that the $100% conversion for acetic acid and 95.7% for phenol at 800 C over the undiluted catalyst while 97% of phenol conversion was achieved while SiC dilution applied.