scholarly journals Effect of nanostructured supports on catalytic methane decomposition

2000 ◽  
Vol 72 (1-2) ◽  
pp. 327-331 ◽  
Author(s):  
L. Ji ◽  
S. Tang ◽  
P. Chen ◽  
H. C. Zeng ◽  
J. Lin ◽  
...  
Keyword(s):  
Carbon Deposition ◽  
Sol Gel ◽  
Methane Decomposition ◽  
Molar Ratio ◽  
Carbon Formation ◽  
Commercial Catalyst ◽  
Support Particle ◽  
Different Types ◽  
Support Size ◽  
Effect Of Support

Carbon deposition from catalytic methane decomposition has drawn increasing interest recently. Previously, we have found the carbon formation depends on the crystalline structure of the support, following the trend of Ni/CeO2 > Ni/CaO > Ni/MgO, because Ni supported on MgO is uniformly dispersed and can stabilize high-x CH x intermediates. We have also found that the addition of Pt can inhibit the carbon deposition on Co/Al2O3 because the alloying between Pt and Co results in the better dispersion of Co on the support. Furthermore, it was revealed that by judging the Ni/Mg molar ratio from 1 to 0.25 we could reduce the diameter of deposited carbon nanotubes from 20 to 12 nm, with substantially smaller production rate. All of these previous studies indicated that better dispersion of the supported metal would benefit the decreasing of carbon deposition. Here we present our recent investigation of the effect of support particle size on the carbon deposition. Three different types of 10 wt% Co/Al2O3 catalysts were prepared: Co on commercial Al2O3 (Cat 1), Co on sol-gel-processed Al2O3 (Cat 2), and sol-gel-made homogeneous Co-in-Al2O3 (Cat 3). TEM showed that the diameter of the Co3O4 particles in sol-gel Al2O3 is only around 6 nm, while it is 20-40 nm in the commercial catalyst. By using XRD and FTIR, Co was identified as crystalline Co3O4 in the as-prepared Cat 1 sample, CoAl2O4 in Cat 2, and amorphous Al2O3 in Cat 3, indicating the best dispersion in Cat 3. Methane CO2 reforming was studied on the three catalysts. Longer lifetime was measured for Cat 3 as compared to those on Cat 1 and Cat 2 (>20 h vs. 1 h). The support size effect is discussed.

scholarly journals Effect of Support Particle Morphology of Ni Catalysts on Growth of Carbon Nanotubes by Methane Decomposition

2006 ◽  
Vol 49 (6) ◽  
pp. 308-314 ◽  
Author(s):  
Akinori Nakayama ◽  
Kouta Asai ◽  
Yoshiyuki Nagayasu ◽  
Shinji Iwamoto ◽  
Eriko Yagasaki ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Particle Morphology ◽  
Methane Decomposition ◽  
Ni Catalysts ◽  
Support Particle ◽  
Effect Of Support

scholarly journals Dry Reforming of Propane over γ-Al2O3 and Nickel Foam Supported Novel SrNiO3 Perovskite Catalyst

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 68 ◽  
Author(s):  
Sudhakaran M.S.P ◽  
Md. Hossain ◽  
Gnanaselvan Gnanasekaran ◽  
Young Mok
Keyword(s):  
Catalytic Activity ◽  
Carbon Deposition ◽  
Nickel Foam ◽  
Sol Gel ◽  
Dry Reforming ◽  
Catalyst Characterization ◽  
Carbon Formation ◽  
Perovskite Catalyst ◽  
X Ray ◽  
Activity Test

The SrNiO3 perovskite catalyst was synthesized by the citrate sol-gel method and supported on γ-Al2O3 and Nickel foam, which was used to produce syngas (CO and H2) via dry reforming of propane (DRP). Several techniques characterized the physicochemical properties of the fresh and spent perovskite catalyst. The X-ray diffractograms (XRD) characterization confirmed the formation of the perovskite compound. Before the catalytic activity test, SrNiO3 perovskite catalyst was reduced in the H2 atmosphere. Results indicated that the H2 reduction slightly increased the activity of the SrNiO3 perovskite catalyst. The catalytic activity was examined for the CO2/C3H8 ratio of 3 and reaction temperatures in the range of 550 °C–700 °C. The results from the catalytic study achieved 88% conversion of C3H8 and 66% conversion of CO2 with SrNiO3/NiF at 700 °C. Also, syngas with a maximum concentration of 21 vol.% of CO and 29 vol.% of H2 was produced from the DRP. The strong basicity of SrNiO3 perovskite enhanced the CO selectivity, resulting in minimal carbon formation. Post reaction catalyst characterization showed the presence of carbon deposition which could have originated from propane decomposition.

Hydrogen Production by Carbon-Catalyzed Methane Decomposition Via Thermogravimetry

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Vidyasagar Shilapuram ◽  
Nesrin Ozalp
Keyword(s):  
Weight Gain ◽  
Hydrogen Production ◽  
Reaction Temperature ◽  
Reaction Rate ◽  
Carbon Deposition ◽  
Activated Carbons ◽  
Catalyst Activity ◽  
High Energy ◽  
Methane Decomposition ◽  
Carbon Formation

Hydrogen is a high energy content fuel and methane is currently the most preferred feedstock for hydrogen production. Direct thermal splitting of methane offers the cleanest technique to produce hydrogen and carbon as coproduct fuel. Carbonaceous catalysts have significant impact on methane to hydrogen conversion. This study presents thermogravimetric experiment results of carbon-catalyzed methane decomposition using commercial catalyst. Results are presented in terms of carbon formation rate, amount of carbon deposition on the catalyst, sustainability factor, catalyst activity, and kinetics of the reaction. The results show that weight gain because of carbon formation depends on reaction temperature, methane volume percent in the feed gas, and nature of the carbonaceous catalyst. It was observed that the reaction rate was dominant at the beginning, and deactivation rate was dominant toward the end of reaction. X-ray diffraction (XRD) and scanning electron microscopic (SEM) analysis of deactivated catalytic samples show decreasing disorder with increasing reaction temperature. Finally, performance comparison of activated carbons (ACs) studied in literature shows that activated carbon sample chosen in this study outperforms in terms of carbon deposition, reaction rate, carbon weight gain, and sustainability factor.

Efficient Micromixing for Continuous Biodiesel Production from Jatropha Oil

2018 ◽  
Vol 9 (1) ◽  
pp. 133-139
Author(s):  
Waleed S. Mohammed ◽  
Ahmed H. El-Shazly ◽  
Marwa F. Elkady ◽  
Masahiro Ohshima
Keyword(s):  
Methyl Esters ◽  
Continuous Process ◽  
Sol Gel ◽  
Average Diameter ◽  
Biodiesel Production ◽  
High Mass ◽  
Molar Ratio ◽  
Jatropha Oil ◽  
Energy Deficiency ◽  
Gel Preparation

Introduction: The utilization of biodiesel as an alternative fuel is turning out to be progressively famous these days because of worldwide energy deficiency. The enthusiasm for utilizing Jatropha as a non-edible oil feedstock is quickly developing. The performance of the base catalyzed methanolysis reaction could be improved by a continuous process through a microreactor in view of the high mass transfer coefficient of this technique. Materials & Methods: Nanozirconium tungstovanadate, which was synthetized using sol-gel preparation method, was utilized in a complementary step for biodiesel production process. The prepared material has an average diameter of 0.066 &µm. Results: First, the NaOH catalyzed methanolysis of Jatropha oil was investigated in a continuous microreactor, and the efficient mixing over different mixers and its impact on the biodiesel yield were studied under varied conditions. Second, the effect of adding the nanocatalyst as a second stage was investigated. Conclusion: The maximum percentage of produced methyl esters from Jatropha oil was 98.1% using a methanol/Jatropha oil molar ratio of 11 within 94 s using 1% NaOH at 60 &°C. The same maximum conversion ratio was recorded with the nanocatalyst via only 0.3% NaOH.

Mechanisms of methane decomposition and carbon species oxidation on the Pr0.42Sr0.6Co0.2Fe0.7Nb0.1O3−σ electrode with high catalytic activity

2015 ◽  
Vol 3 (45) ◽  
pp. 22816-22823 ◽  
Author(s):  
Peng Zhang ◽  
Guoqing Guan ◽  
Deni S. Khaerudini ◽  
Xiaogang Hao ◽  
Chunfeng Xue ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Carbon Deposition ◽  
Methane Decomposition ◽  
High Catalytic Activity ◽  
Carbon Species

Carbon deposition characteristics on PSCFN and Ni–YSZ due to thermal CH4 decomposition are investigated by using TPR technique.

scholarly journals Green Synthesis of N/Zr Co-Doped TiO2 for Photocatalytic Degradation of p-Nitrophenol in Wastewater

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 235
Author(s):  
Hayette Benkhennouche-Bouchene ◽  
Julien G. Mahy ◽  
Cédric Wolfs ◽  
Bénédicte Vertruyen ◽  
Dirk Poelman ◽  
...  
Keyword(s):  
Visible Light ◽  
Tio2 Nanoparticles ◽  
Sol Gel ◽  
Visible Region ◽  
Chemical Properties ◽  
Pure Tio2 ◽  
Molar Ratio ◽  
Xps Spectra ◽  
Doped Tio2 ◽  
Co Doped

TiO2 prepared by a green aqueous sol–gel peptization process is co-doped with nitrogen and zirconium to improve and extend its photoactivity to the visible region. Two nitrogen precursors are used: urea and triethylamine; zirconium (IV) tert-butoxide is added as a source of zirconia. The N/Ti molar ratio is fixed regardless of the chosen nitrogen precursor while the quantity of zirconia is set to 0.7, 1.4, 2, or 2.8 mol%. The performance and physico-chemical properties of these materials are compared with the commercial Evonik P25 photocatalyst. For all doped and co-doped samples, TiO2 nanoparticles of 4 to 8 nm of size are formed of anatase-brookite phases, with a specific surface area between 125 and 280 m2 g−1 vs. 50 m2 g−1 for the commercial P25 photocatalyst. X-ray photoelectron (XPS) measurements show that nitrogen is incorporated into the TiO2 materials through Ti-O-N bonds allowing light absorption in the visible region. The XPS spectra of the Zr-(co)doped powders show the presence of TiO2-ZrO2 mixed oxide materials. Under visible light, the best co-doped sample gives a degradation of p-nitrophenol (PNP) equal to 70% instead of 25% with pure TiO2 and 10% with P25 under the same conditions. Similarly, the photocatalytic activity improved under UV/visible reaching 95% with the best sample compared to 50% with pure TiO2. This study suggests that N/Zr co-doped TiO2 nanoparticles can be produced in a safe and energy-efficient way while being markedly more active than state-of-the-art photocatalytic materials under visible light.

scholarly journals Ni-γ-AL2O3 catalysts for obtaining nanocarbon by decomposition of natural gas

2021 ◽  
Author(s):  
Hikmet Ibrahimov ◽  
Sara Malikli ◽  
Zenfira Ibrahimova ◽  
Rahim Babali ◽  
Sevinc Aleskerova
Keyword(s):  
Natural Gas ◽  
Specific Surface ◽  
Catalytic Converter ◽  
Sol Gel ◽  
Nickel Content ◽  
Maximum Yield ◽  
Methane Decomposition ◽  
Impregnation Method ◽  
Decomposition Of Methane ◽  
Gas Supply

Abstractγ-Al2O3 was synthesized by the Sol–gel method, Ni (NO3)2 was placed in the pores by the impregnation method, and Ni-γ-Al2O3 was obtained by pyrolysis in a hydrogen stream in a CVD device. By the method of chemical vapors phase deposition (CVD) on Ni-Al2O3 catalytic converter with decomposition of methane in the natural gas produced carbon nanotubes (CNT) (Chunduri et al. in Mater Express 4(3):235–241, 2014; Zhou et al. in Appl Catal B 208:44–59, 2017). The catalytic activity of the catalysts in methane decomposition was examined from 650 °C to 900 °C by the method of chemical vapors phase deposition (CVD), the yield of CNTs tends to increase with the growth at the ratio of natural gas supply to hydrogen. The specific surface increases with an increase of nickel content and can reach 265.5 m2/g for a sample of 2% Ni-A12O3 at 850 °C. Growth at the temperature of methane decomposition leads to reduction in its specific surface. It has been established that the use of the Ni-Cu/γ-Al2O3 catalytic system, in which copper acts as a stabilizing additive, makes it possible to double the maximum yield of the carbon product during the decomposition of natural gas.

Sol-Gel Synthesis and Characterization of Ultrafine ZrSiO4 Powder

2014 ◽  
Vol 906 ◽  
pp. 66-71
Author(s):  
Zhen Quan Li ◽  
Qiang Zhen ◽  
Ya Li Wang
Keyword(s):  
Wavelength Range ◽  
High Purity ◽  
Raw Materials ◽  
Formation Rate ◽  
Sol Gel ◽  
Molar Ratio ◽  
Sem And Tem ◽  
Homogeneous Product ◽  
Sol Gel Synthesis ◽  
Calcined Temperature

High purity ZrSiO4 powder were synthesized using Si (C2H5O)4 and ZrOCl2·8H2O as raw materials by the sol-gel method, LiCl was added as mineralizer to promote crystallization of zircon. The influences of molar ratio of Zr:Si, calcined time and calcined temperature on the synthesis of ZrSiO4 powder were investigated. XRD, SEM and TEM were used to characterize the powders. It was found that when the molar ratio of Zr:Si was 1:1.2, the calcined temperature was 1600°C and the calcined time was 4h, the high purity ZrSiO4 ultrafine powder was obtained. The ZrSiO4 formation began at 1300°C and when the gel was calcined at 1600°Cfor 4 h, the formation rate of ZrSiO4 was up to 95%. SEM and TEM studies reveal a homogeneous product with particle sizes on the order of 0.1-1μm. The IR emissivity of ultrafine ZrSiO4 is 0.892 at the whole wavelength range, and that is up to 0.951 at the wavelength range of 8-14 μm.

Effect of Complexing Agent on Morphology and Crystal Structure of La1-xCexCoO3 (x=0, 0.2, and 0.4) Perovskite-Type Mixed Oxides Catalyst Prepared by Sol-Gel Method

2010 ◽  
Vol 658 ◽  
pp. 29-32 ◽  
Author(s):  
Kanit Soongprasit ◽  
Duangdao Aht-Ong ◽  
Viboon Sricharoenchaikul ◽  
Duangduen Atong
Keyword(s):  
Crystal Structure ◽  
Polyvinyl Alcohol ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Value Added ◽  
Molar Ratio ◽  
Complexing Agent ◽  
Nitrate Hexahydrate ◽  
Mixed Oxide Catalysts ◽  
Perovskite Type

. La1-xCexCoO3 (x=0, 0.2, and 0.4) perovskite-type mixed oxides using polyvinyl alcohol (PVA) as complexing agent at two molar ratio of metal ion to PVA (1:1 and 1:2) were successfully prepared by sol-gel process. The precursor included lanthanum (II) nitrate hexahydrate, cerium (II) nitrate hexahydrate, and cobalt (II) nitrate hexahydrate where polyvinyl alcohol was added as complexing agent. The suitable condition of Cerium (Ce) substitution and PVA molar ratio were established for further application in hydrocarbon conversion to high value added products. TGA thermogram of as-prepared precursor showed that PVA absolutely decomposed at temperature higher than 500°C. XRD patterns of calcined catalyst showed both LaCoO3 rhombohedral and CeO2 cubic structures that confirmed the formation of mixed crystal structure. Nevertheless, Co3O4 slightly appeared with low peak intensity which came from the oxidation reaction of as-prepared catalyst during calcinations. XRD showed that PVA did not effect to crystal structure of synthesized catalyst. Higher PVA content added in the precursor cause the reduction of crystal growth of catalyst in calcinations step. In contrast, morphology of catalyst is directly related with PVA content such that the spongy and sheet-like structure were formed with increasing PVA content which prevented the agglomeration of particles. The results showed that PVA content play an important role in morphology of perovskite-type mixed oxide catalysts but did not affected to their crystal structures.

scholarly journals Small-angle scattering investigation of silica xerogels and sonogels prepared with ionic liquid pyridinium tetrafluoroborate

2017 ◽  
Vol 11 (3) ◽  
pp. 229-233 ◽  
Author(s):  
László Almásy ◽  
Ana-Maria Putz ◽  
Adél Len ◽  
Josef Plestil ◽  
Cecilia Savii
Keyword(s):  
Ionic Liquid ◽  
Small Angle ◽  
Sol Gel ◽  
Molar Ratio ◽  
Strong Increase ◽  
Silica Xerogels ◽  
X Ray Scattering ◽  
Angle Scattering ◽  
Gel Processing ◽  
Functionalized Alkoxide

Silica matrices were prepared via acid catalysed sol-gel processing augmented with sonocatalysis. As silica precursors, a mixture of tetra-functionalized alkoxide (TMOS) and three-functionalized alkoxide methyl-trimethoxysilane (MTMS) were employed. Ionic liquid N-butyl-3-methylpyridinium tetrafluoroborate ([bmPy][BF4]), was used in various proportions, aiming to catalyse the sol-gel reactions, and to influence the mesoporous silica materials properties, serving as pore template. Small-angle neutron (SANS) and small-angle X-ray scattering (SAXS) techniques were used to explore the xerogels and sonogels microstructure evolution as a function of the IL/Si molar ratio. The results show a strong increase of the primary particle size under the influence of the ionic liquid. Ultrasonic agitation leads to further size increase by ca. 10%.

Sign in / Sign up

Export Citation Format

Share Document