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1.
《International Journal of Hydrogen Energy》2020,45(36):18502-18518
Ni-based catalysts were prepared using two hydroxyapatites (Ca-HA1, SBET = 7 m2/g and Ca-HA2, SBET = 60 m2/g) with different physico-chemical properties. The objective of the study was to evaluate the performance of these two materials as promising supports for dry reforming reaction (DRM) as well as to investigate the influence of different process parameters, such as temperature, pressure, time and catalyst pretreatment on the performance of these two catalysts. Thermodynamic calculations were performed to determine the conditions that would limit solid carbon deposit and favor the reactants conversion. Then, an experimental parametric study was carried out to investigate the impact of the temperature, pressure, catalyst pretreatment and support thermal treatment on the catalysts performance. The results showed that the catalyst pretreatment allowed the reduction of the nickel particles in a higher extent, which resulted in better catalytic performance when compared to the catalysts without pretreatment. High temperatures around 700 °C and low pressures around 1.6 bar were required to attain high CH4 and CO2 conversions around 70–80% as well as high H2 and CO selectivity around 90% for 90 h of time on stream. In all cases, Ni/Ca-HA2 catalyst presented better catalytic performance than Ni/Ca-HA1 due to the presence of smaller nickel particles (10–20 nm), stronger basicity, higher density of basic sites (0.23 mmol g−1) as well as higher specific surface area (SBET = 60 m2/g) of the Ca-HA2 support. Ni/Ca-HA2 catalyst was highly active (initial methane conversion: 75%) and relatively stable during 90 h of TOS and its catalytic behavior was comparable with the performance of Ni-based catalysts prepared with conventional supports reported in the literature. 相似文献
2.
《International Journal of Hydrogen Energy》2019,44(1):246-255
Fe modified natural clay supported Ni catalysts promoted with Lanthanum (La), aluminum (Al) and Manganese (Mn) were prepared by impregnation method. Calcined or reduced catalysts were characterized by Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), H2-temperature programmed reduction (H2-TPR) and CO2-temperature programmed desorption (CO2-TPD). The addition of La, Al and Mn obviously affected the specific surface area and catalyst basicity. The presence of La, Al and Mn resulted in smaller Ni0 crystallite size and further promoted Ni dispersion. Al-promoted catalysts improved the Ni reducibility compared to La and Mn-promoted catalysts. After a reduction step at 900 °C, the studied catalysts have been tested in dry reforming of methane (DRM) from 850 to 600 °C. Al-promoted Fe-clay based catalysts presented the best catalytic performance in DRM. Both CH4 and CO2 conversions, and H2/CO molar ratio followed the trend of thermodynamic calculations. Furthermore all conversions and H2/CO molar ratio were close to theoretical values that were also forecasted by thermodynamics by means of HSC Chemistry 5.0. 相似文献
3.
《International Journal of Hydrogen Energy》2021,46(62):31608-31622
Addition of rare earth oxide, especially lanthanide oxide, was regarded as a promising strategy to improve the carbon resistance for Nickel-based catalysts in dry reforming of methane (DRM). In this work, Nickel-based catalysts containing lanthanide oxides (NiLa/SiO2, NiCe/SiO2, NiSm/SiO2, and NiGd/SiO2) were prepared and employed to catalyze DRM. Lanthanide oxide affected the formation of Ni nanoparticles in different size. In NiLa/SiO2 and NiCe/SiO2, Ni nanoparticles maintained relatively small size (4 nm), while in NiSm/SiO2 and NiGd/SiO2, nickel particles were in large size (8 nm). NiLa/SiO2 and NiCe/SiO2 exhibited better stability than the other two catalysts, with CH4 conversion decreasing from 64.6 to 57.6% and 61.6 to 60.3%, respectively in 10 h on stream. The kinetic study confirmed that adding lanthanide oxide significantly affected the activation energy of CH4 dissociation and CO2 dissociation. Compared to monometallic Ni/SiO2, the presence of Sm and Gd suppressed CO2 dissociation, and introduction of Ce and La effectively promoted CO2 dissociation. These characters contributed to the higher carbon resistance and good stability for NiLa/SiO2 and NiCe/SiO2 catalysts in DRM reaction. 相似文献
4.
Gilvan P. Figueredo Rodolfo L.B.A. Medeiros Heloísa P. Macedo Ângelo A.S. de Oliveira Renata M. Braga José M.R. Mercury Marcus A.F. Melo Dulce M.A. Melo 《International Journal of Hydrogen Energy》2018,43(24):11022-11037
A systematic and comparative study was made to determine the influence of perovskite-type LaAlO3 and commercial α-Al2O3 on the performance of nickel-based catalysts in dry reforming of methane (DRM). The perovskite-type LaAlO3 was selected due to its characteristics of solid state semiconductor with oxygen vacancies and high structural stability. The catalysts were characterized by X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), N2 adsorption-desorption, temperature programmed reduction (TPR-H2), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The catalyst performance was evaluated based on activity tests (600–800 °C) and short- and long-term stability (10 and 20 h) at 700 °C at a GHSV (Gas Hourly Space Velocity) of 18 and 72 L g?1 h?1. The TPR-H2 profiles indicate that the oxygen vacancies on the perovskite surface exerted a strong effect on the reduction temperature and reducibility of the NiO nanoparticles, resulting in weak Ni0/support interaction. The results of the tests after 10 h under GHSV of 18 L g?1 h?1 indicate that the Ni/LaAlO3 catalyst is 7.8 and 11.5% more stable than Ni/α-Al2O3 in the conversions of CH4 and CO2, respectively. The higher stability and activity of Ni/LaAlO3 is directly ascribed to the presence of NiO (3.38 wt%) after activation, which promoted the formation of carbon nanotubes (CNT) and increased the dispersion of the metallic phase. Even under severe conditions of activation and reaction (high GHSV), as in the long-term test, the Ni/LaAlO3 catalyst showed a 37.2% higher H2 yield than the Ni/α-Al2O3. Analyses by TEM indicate that the Ni/α-Al2O3 catalyst exhibited deactivation problems associated with sintering effects. Thus, the presence of structural defects and surfaces rich in oxygen vacancies makes LaAlO3 perovskite a potential support for application in methane catalytic reforming processes. 相似文献
5.
Hydrogen and/or syngas production by combined steam and dry reforming of methane on nickel catalysts
《International Journal of Hydrogen Energy》2020,45(49):26254-26264
Two alumina supported Ni catalysts with pore sizes of 5.4 nm and 9 nm were synthetized, characterized and tested in the Combined Steam and Dry Reforming of Methane (CSDRM) for the production of hydrogen rich gases or syngas. The reaction mixture was designed to simulate the composition of real clean biogas, the addition of water being made in order to have molar ratios of H2O:CO2 corresponding to 2.5:1, 7.5:1 and 12.5:1. Structural and functional characterization of catalysts revealed that Ni/Al2O3 with larger pore size shows better characteristics: higher surface area, lower Ni crystallite sizes, higher proportion of stronger catalytic sites for hydrogen adsorption, and higher capacity to adsorb CO2. At all studied temperatures, for a CH4:CO2:H2O molar ratio of 1:0.48:1.2, a (H2+CO) mixture with H2:CO ratio around 2.5 is obtained. For the production of hydrogen rich gases, the optimum conditions are: CH4:CO2:H2O = 1:0.48:6.1 and 600 °C. No catalyst deactivation was observed after 24 h time on stream for both studied catalysts, and no carbon deposition was revealed on the used catalysts surface regardless the reaction conditions. 相似文献
6.
Zahra Taherian Mardali Yousefpour Mohammad Tajally Behnam Khoshandam 《International Journal of Hydrogen Energy》2017,42(39):24811-24822
Methane reforming with CO2 over Samaria-promoted Ni and Co/SBA-15 was comparatively investigated. The Co, Ni (10%wt) and Sm (0.5, 1 and 1.5%wt) ions were introduced by two-solvent impregnation method. The Ni and Co catalysts with/without promoter, were examined by N2 adsorption-desorption, x-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), temperature programmed reduction (TPR) and thermogravimetric analysis (TGA) methods, and then evaluated in CO2 reforming of methane. The XRD and TEM results indicated that Ni and Co/SBA-15 promoted by 1%wt of Samaria, had the smallest NiO and Co3O4 particles size and the highest dispersion; as a result, they would rather studying dry reforming of methane test. Catalytic results indicated that Samaria promoted Ni/SBA-15 had the highest conversion (CH4 conversion~58% at 700 °C), while a remarkable decrease of catalytic activity was observed over Samaria-promoted Co/SBA-15 (CH4 conversion~25% at 700 °C). The positive effect of Samaria on Ni/SBA-15 catalyst activity is probably due to smaller NiO particles, higher NiO dispersion and lower trend to carbon deposition. On the contrary, the negative effect of Samaria on Co/SBA-15 catalyst activity is maybe due to Co oxidation to inactive phase and sintering of Co particles in high temperatures. 相似文献
7.
Ce0.75Zr0.25O2 solid solution supported Ru catalysts were prepared and tested for CH4–CO2 reforming. The effect of Ru content on the properties of the catalysts was investigated by means of N2 adsorption–desorption, H2-TPR/MS, XRD, XPS, CO chemisorption and H2-TPD/MS. It was found that the highly dispersed Ru species favored the interaction between Ru and Ce0.75Zr0.25O2. The reduced Ce0.75Zr0.25O2 was able to store hydrogen, while Ru promoted the reduction of Ce0.75Zr0.25O2. Under the identical conditions, the CH4 and CO2 conversions of the catalysts increased with the increase of Ru content, however, the turnover frequencies of CH4 and CO2 were higher for the catalysts with lower Ru contents, which may be resulted from the strong interaction between Ru and Ce0.75Zr0.25O2. The Ru catalyst exhibited good stability and excellent resistance to carbon deposition. Remarkably, zirconium and cerium hydrides were detected in the used catalyst, which may participate in the elimination of the carbon deposit. Apart from the nature of metallic Ru and the redox property of Ce0.75Zr0.25O2, we suggest that the excellent resistance of the catalyst to carbon deposition is also attributed to the hydrogen storage of the reduced Ce0.75Zr0.25O2. 相似文献
8.
Sufang He Zhanqiang Mei Nengsheng Liu Lei Zhang Jichang Lu Xiaofeng Li Jing Wang Dedong He Yongming Luo 《International Journal of Hydrogen Energy》2017,42(21):14429-14438
The effect of nickel precursor on Ni/SBA-15 catalysts was studied in ethanol steam reforming (ESR) for hydrogen production. These catalysts were prepared via incipient-wetness impregnation method using nickel nitrate and nickel citrate precursors, respectively (denoted as Ni/SBA-15(N) and Ni/SBA-15(C), respectively), and characterized by various techniques including H2-TPR, XRD, TEM and TG. It was found that the use of nickel citrate precursor, compared to nickel nitrate precursor, could greatly strengthen the NiO-support interaction and promote the homogeneous distribution of nickel species, to obtain the small nickel particles with high dispersion. After a 25 h time-on-stream test, much lower coke deposition was formed over Ni/SBA-15(C) than Ni/SBA-15(N). Moreover, NiCx species had be found over the used Ni/SBA-15(C), in which the carbon could be removed easily at lower temperature to exposure the active Ni sites; While carbon nanofibers with regular graphite-structure were the primary coke species over the spent Ni/SBA-15(N), which was difficultly remove and thus covered the active Ni sites easily. Due to these, Ni/SBA-15(C) displayed the higher catalytic activities and better stabilities in ESR than Ni/SBA-15(N). In summary, nickel citrate is an excellent precursor for the preparation of Ni/SBA-15 catalysts with high dispersion and strong interaction. 相似文献
9.
Berna Erdogan Huseyin Arbag Nail Yasyerli 《International Journal of Hydrogen Energy》2018,43(3):1396-1405
In this study, the activity of the mesoporous SBA-15 supported Ni, Co and NiCo catalysts prepared by the wet-impregnation were investigated in dry reforming of methane reaction. The catalysts were characterized by XRD, TPR, N2 adsorption-desorption isotherms, SEM, TEM and TG/DT techniques before and/or after activity tests. N2 adsorption-desorption isotherm of the all catalysts were consistent with Type IV isotherm, indicating mesoporous structures. TEM images of bimetallic NiCo catalysts clearly proved the presence of characteristic honeycomb structure. Incorporation Co into SBA-15 supported Ni catalysts inhibited the agglomeration of the nickel particles due to the formation of NiCo alloy. Activity test results showed that bimetallic 4Ni1Co@SBA-15 catalyst (Ni/Co:4/1) gave highly promising activity with high methane (73%) and carbon dioxide (89%) conversion values at 750 °C. Co incorporation into SBA-15 supported Ni catalyst significantly decreased the coke formation during dry reforming of methane. 相似文献
10.
A series of Ce-incorporated SBA-15 mesoporous materials were synthesized through direct hydrothermal synthesis method and further impregnated with 12 wt.% Ni. The samples were characterized by ICP-AES, XRD, N2 physisorption, XPS, TPR, H2 chemisorption, TGA, temperature-programmed hydrogenation (TPH) and TEM measurements. The low-angle XRD and N2 physisorption results showed the Ce successfully incorporated into the framework of SBA-15. The catalytic properties of these catalysts were investigated in methane reforming with CO2. The Ce/Si molar ratio had a significant influence on the catalytic performance. The highest catalytic activity and long-term stability were obtained over the Ni/Ce-SBA-15 (Ce/Si = 0.04) sample. The improved catalytic behavior could be attributed to the cerium impact in the framework of SBA-15, where cerium promoted the dispersion of nano-sized Ni species and inhibited the carbon formation. In comparison with the effect of CeO2 crystallites in SBA-15, cerium in the framework of SBA-15 promoted the formation of the nickel metallic particles with smaller size. The XRD and TGA results exhibited that carbon deposition was responsible for activity loss of Ni/SBA-15 and Ni/Ce-SBA-15 (Ce/Si = 0.06) catalysts. TEM results showed that the hexagonal mesopores of SBA-15 were still kept intact after reaction and the pore walls of SBA-15 prevented the aggregation of nickel. 相似文献
11.
Seyed Mehdi Mousavi Fereshteh Meshkani Mehran Rezaei 《International Journal of Hydrogen Energy》2018,43(13):6532-6538
The influence of the various promoters (Zr, La and Mg) on the physicochemical and catalytic characteristics of the 10% Ni/Ce0.95Mn0.05O2 solid solution catalyst were investigated in methane dry reforming at atmospheric pressure. The co-precipitation method was employed for the synthesis of the catalyst carrier. The catalysts were characterized by BET, XRD, H2-TPR and TPO analyses. The obtained results revealed that the addition of the promoters increased the BET surface area and the highest BET surface area was related to the catalyst promoted by La (58.99 m2/gr). The results of the TPR analysis showed that the broad peak related to the reduction of NiO species was shifted to the higher temperature, indicating the enhancement of the interaction between NiO particles and the support due to the addition of the promoter. The obtained results indicated that the addition of Mg improved the activity (CH4 conversion (%) = 67 at 700 °C) and stability and reduced the amount of deposited carbon. Furthermore smaller Ni crystalline size was related to the catalyst promoted by Mg (10.0 nm). The highest and the lowest amount of carbon deposition was observed on the 10Ni/Ce0.95Mn0.05O2 and 10Ni/Ce0.85Zr0.10Mn0.05O2 catalysts, respectively. 相似文献
12.
A series of MgO-coated SBA-15 mesoporous silica with MgO contents ranging from 2 wt% to 15 wt% have been successfully synthesized by a simple one-pot synthesis method and further impregnated with 10 wt% Ni. Ni/SBA-15 modified with 8 wt% MgO was also prepared by conventional impregnation method. The materials were characterized by means of XRD, N2 physisorption, TEM by applying high-angle annular dark field (HAADF), XPS, CO2-TPD, TGA and temperature-programmed hydrogenation (TPH) techniques, and their catalytic performance was tested for methane reforming with CO2. The results showed that MgO was successfully coated on the walls of mesoporous silica and the mesoporous structure of SBA-15 was well maintained after MgO modification. Compared to MgO-impregnated material, MgO-coated counterpart showed a better order in the mesostructure and more medium basic sites. The addition of MgO enhanced initial catalytic activity of Ni/SBA-15, and the catalyst with 8 wt% MgO coating showed the most excellent catalytic activity. The MgO coating induced an improved dispersion of Ni species and larger medium basic sites than that of MgO impregnation, which led to an enhanced long-term stability and resistance to carbon formation. The deposition of graphitic carbon species during the reaction was the main reason for the deactivation of Ni/SBA-15 catalyst. 相似文献
13.
Min Hye Youn Jeong Gil SeoJi Chul Jung Sunyoung ParkIn Kyu Song 《International Journal of Hydrogen Energy》2009
Mesoporous yttria-stabilized zirconia (YSZ-X) supports with different Y/Zr molar ratio (X) were prepared by a sol–gel method. 20 wt% Ni catalysts supported on YSZ-X (X = 0, 0.1, 0.2, and 0.3) were then prepared by an incipient wetness impregnation method for use in hydrogen production by auto-thermal reforming of ethanol. The effect of Y/Zr molar ratio (X) on the catalytic performance of Ni/YSZ-X (X = 0, 0.1, 0.2, and 0.3) catalysts was investigated. Hydrogen selectivity and by-product distributions over the catalysts were different depending on the Y/Zr molar ratio (X). Hydrogen selectivity over Ni/YSZ-X (X = 0, 0.1, 0.2, and 0.3) catalysts showed a volcano-shaped curve with respect to Y/Zr molar ratio (X). Among the catalysts tested, Ni/YSZ-0.1 showed the best catalytic performance and the lowest carbon deposition in hydrogen production by auto-thermal reforming of ethanol. High reducibility and excellent structural stability of Ni/YSZ-0.1 catalyst were responsible for its superior catalytic performance. 相似文献
14.
《International Journal of Hydrogen Energy》2022,47(90):38242-38257
Herein, a series of 5NixHo/YZr (x = 1, 2, 3, 4, 5 wt%) materials, never reported before, were tested in DRM reaction and characterized using several techniques like Nitrogen physisorption, X-ray diffraction, UV–vis and RAMAN spectroscopies, High Resolution Transmission Electron Microscopy, H2-Temperature Programmed Reduction, CO2-Temperature Programmed De-adsorption and Thermogravimetry. The incorporation of Yttria in the structure modifies pore sizes and stabilizes cubic Zirconia phases, whereas the addition of Ho as a promotor brings stable cubic zirconia, stable cubic holmium zirconium oxide phase and a wide range of reducible NiO-interacted species. In particular, an optimum Ho loading of 4 wt%, characterized by a minimum bandgap, strong suppression of RWGS reaction and maximum amount of reducible NiO-interacted species allows to achieve 84.1% H2 yield and 84.1% CO yield constantly over 420-min time on stream. The least basic sites availability over 5Ni5Ho/YZr results into inferior catalyst performance. 相似文献
15.
Metal oxide-stabilized mesoporous zirconia supports (M–ZrO2) with different metal oxide stabilizer (M = Zr, Y, La, Ca, and Mg) were prepared by a templating sol–gel method. 20 wt% Ni catalysts supported on M–ZrO2 (M = Zr, Y, La, Ca, and Mg) were then prepared by an incipient wetness impregnation method for use in hydrogen production by auto-thermal reforming of ethanol. The effect of metal oxide stabilizer (M = Zr, Y, La, Ca, and Mg) on the catalytic performance of supported nickel catalysts was investigated. Ni/M–ZrO2 (M = Y, La, Ca, and Mg) catalysts exhibited a higher catalytic performance than Ni/Zr–ZrO2, because surface oxygen vacancy of M–ZrO2 (M = Y, La, Ca, and Mg) and reducibility of Ni/M–ZrO2 (M = Y, La, Ca, and Mg) were enhanced by the addition of lower valent metal cation. Hydrogen yield over Ni/M–ZrO2 (M = Zr, Y, La, Ca, and Mg) catalyst was monotonically increased with increasing both surface oxygen vacancy of M–ZrO2 support and reducibility of Ni/M–ZrO2 catalyst. Among the catalysts tested, Ni catalyst supported on yttria-stabilized mesoporous zirconia (Ni/Y–ZrO2) showed the best catalytic performance. 相似文献
16.
Alireza Dehghanpoor-Gharashah Mehran Rezaei Fereshteh Meshkani 《International Journal of Hydrogen Energy》2021,46(43):22454-22462
Dry reforming of glycerol is an interesting method for syngas production due to its H2/CO ≈ 1 that is suitable for FT synthesis. In this study, the performance of the Ni/MgO.Al2O3 catalysts with different nickel contents was investigated in glycerol dry reforming. The MgO.Al2O3 carrier was prepared by a simple sol-gel method and the nickel-based catalysts were synthesized by the wet impregnation method. The prepared catalysts possessed high BET surface area and pore volume. The TPR analysis showed a strong interaction between Ni and the catalyst support. The results demonstrated that the glycerol conversion decreased by increasing in CO2/glycerol (GRR) molar ratio. All the prepared samples showed high stability in glycerol dry reforming during 25 h of reaction, indicating the high resistance of the catalysts against carbon formation. Also, 10 wt%Ni/MgO.Al2O3 catalysts possessed the highest catalytic performance (52% of glycerol conversion at 750 °C) due to the high dispersion of nickel on the prepared carrier. 相似文献
17.
《International Journal of Hydrogen Energy》2019,44(20):9866-9872
Dry reforming of methane (DRM) is a reaction that converts two greenhouse gases, CH4 and CO2, to syngas (H2 + CO). Gas chromatography (GC) is almost exclusively used to evaluate catalyst performance. In order to measure the hydrogen production rate with GC, an inert gas with a constant flow rate is usually fed into the system as an internal standard. In this work, an IR spectroscopy-based method is used to achieve the same technical goal with much higher time resolution and much smaller measurement errors. IR measures the molar fractions of CH4, CO2, CO and H2O in the reaction effluent. By applying general mass balance principle and the relevant reaction stoichiometries, H2 production rate is successfully measured without an internal standard. The results are quite close to those obtained by GC with much higher time resolution, making it possible to observe fast reaction kinetics. 相似文献
18.
Katarzyna Świrk Magnus Rønning Monika Motak Teresa Grzybek Patrick Da Costa 《International Journal of Hydrogen Energy》2021,46(22):12128-12144
Ni-based Mg/Al double-layered hydroxides, also called hydrotalcites (HTs), were co-precipitated with Zr (5 wt%) and impregnated with Y (0.2, 0.4, 0.6 wt%), and compared to the catalyst co-precipitated with both Y (0.4 wt%) and Zr (5 wt%). Their performance in dry reforming of methane was determined in the temperature range of 850–600 °C and stability tests at 700 °C for 5 h. The materials were characterized by X-ray powder diffraction, X-ray fluorescence, nitrogen adsorption/desorption, H2-TPR, CO2-TPD, hydrogen chemisorption, thermogravimetric analysis, transmission electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy. A decrease in reducibility and lower total number of basic sites were observed for the sample promoted only with zirconia compared to the unpromoted material. After promotion with yttrium, no formation of ZrO2–Y2O3 solid solution was evident from XRD. The Ni dispersion was decreased due to decoration of the surface with Y species, leading to blockage of available nickel sites. All Zr and Y promoted samples were, however, more active in DRM than unpromoted HTNi. The co-precipitated Zr and Y catalyst (HTNi-ZrY0.4-cop) exhibited increasing conversion over time, and a H2/CO close to 1 in the isothermal test at 700 °C. H2-TPSR on the spent catalysts revealed that the promotion with yttrium favored regeneration of the catalytic bed, consuming the majority of removable coke and decreasing the formation of unreactive coke. 相似文献
19.
Pedro M. Araújo Kevin M. da Costa Fabio B. Passos 《International Journal of Hydrogen Energy》2021,46(47):24107-24116
Nickel supported on perovskite supports were investigated in the autothermal reforming of methane. The catalysts were prepared by incipient wetness impregnation and characterized by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), N2 physisorption, H2 temperature programmed reduction (H2-TPR), H2 chemisorption, dehydrogenation of cyclohexane model reaction and Raman spectroscopy. The alumina supported catalyst exhibited highest initial conversion and selectivity to H2, however it deactivated. All catalysts with perovskite support were very stable, with Ni/CaTiO3 and Ni/BaTiO3 converting over 70% of the methane. Due to carbon formation, Ni/SrTiO3 conversion was only 50%. Turnover frequency was higher on perovskite supported catalysts. Deactivated Ni/Al2O3 favored total oxidation of methane instead of methane reforming, however the selectivity of catalysts supported on perovskites remained stable. 相似文献
20.
Min Hye Youn Jeong Gil SeoSunyoung Park Ji Chul JungDong Ryul Park In Kyu Song 《International Journal of Hydrogen Energy》2008
Zirconia supports were prepared by a sol–gel method (S-ZrO2) and by a templating sol–gel method (M-ZrO2). Nickel catalysts supported on zirconia were then prepared by an incipient wetness impregnation method for use in hydrogen production by auto-thermal reforming of ethanol. For comparison, a commercial zirconia (C-ZrO2) was also employed as a support for nickel catalyst. The effect of preparation method of zirconia on the catalytic property and catalytic performance of supported nickel catalysts (Ni/C-ZrO2, Ni/S-ZrO2, and Ni/M-ZrO2) was investigated. The crystalline and physical property of zirconia supports and the catalytic performance of supported nickel catalysts were strongly affected by the preparation method of zirconia. BET surface area and pore volume were decreased in the order of M-ZrO2 > S-ZrO2 > C-ZrO2. Both M-ZrO2 and S-ZrO2 supports showed only tetragonal phase of ZrO2, while C-ZrO2 support exhibited tetragonal and monoclinic phases of ZrO2. Crystalline size of nickel species in the Ni/ZrO2 catalysts decreased with increasing surface area and pore volume of ZrO2 supports. All the Ni/ZrO2 catalysts exhibited 100% conversion of ethanol at 500 °C, while product distributions over the Ni/ZrO2 catalysts were different depending on the preparation method of zirconia. Among the catalysts tested, the Ni/M-ZrO2 catalyst showed the best catalytic performance in hydrogen production by auto-thermal reforming of ethanol. Well developed mesopore, high surface area, and pure tetragonal phase of ZrO2 were responsible for fine nickel dispersion and high catalytic performance of Ni/M-ZrO2. C–C bond cleavage reaction and methane steam reforming reaction were also accelerated over the Ni/M-ZrO2 catalyst. 相似文献