scholarly journals Synthesis of Ce/MgO Catalysts for Direct Oxidation of Hibiscus cannabinus Stalks to Vanillin

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1449
Author(s):  
Nur Akila Syakida Idayu Khairul Khairul Anuar ◽  
Anita Ramli ◽  
Lim Jun Wei
Keyword(s):  
Microwave Irradiation ◽  
Significant Loss ◽  
Hibiscus Cannabinus ◽  
Catalyst Loading ◽  
Homogeneous Catalyst ◽  
Direct Oxidation ◽  
N2 Adsorption ◽  
Diffraction Peaks ◽  
Desorption Isotherms ◽  
Adsorption Desorption

One possible method of producing vanillin from biomass is through controlled oxidation of lignin. Direct oxidation of kenaf stalks was chosen without having to separate the cellulose and hemicellulose components from the lignocellulosic biomass. This makes the process greener, as well as saving time. In this paper, Ce/MgO catalysts were developed for oxidation of kenaf stalks and kenaf lignin under microwave irradiation. The catalysts were characterized for their physicochemical properties using XRD and N2 adsorption–desorption isotherms. The synthesized MgO showed the presence of diffraction peaks assigned to cubic MgO while the 30Ce/MgO catalysts showed the presence of cubic fluorite of CeO2. N2 adsorption–desorption isotherms showed that all catalysts possess Type III isotherm according to IUPAC classification, indicating a nonporous structure. All catalysts were tested for direct oxidation of kenaf stalks under 300 W of microwave irradiation using H2O2 as the oxidizing agent at pH 11.5 and temperatures between 160 and 180 °C for 10–30 min with 5–15% catalyst loading. The highest vanillin yields of 3.70% and 2.90% for extracted lignin and direct biomass oxidation were achieved using 30Ce/MgO-48. In comparison, 7.80% and 4.45% were obtained using 2N of NaOH homogeneous catalyst for extracted lignin and direct biomass, respectively, at 170 °C for 20 min. The reusability test shows that 30Ce/MgO can be used up to three cycles without significant loss in catalytic activity. Other compounds detected were 4-vinylguaiacol, syringol and syringaldehyde.

Nanosized Titanium Oxynitride and Molybdenum Oxynitride Particles Assembled in Mesoporous Silica MCM-41

2006 ◽  
Vol 510-511 ◽  
pp. 138-141 ◽  
Author(s):  
Shan Zheng ◽  
Lian Gao
Keyword(s):  
Composite Materials ◽  
Mesoporous Silica ◽  
Mesoporous Materials ◽  
N2 Adsorption ◽  
Xps Spectra ◽  
Desorption Isotherms ◽  
Adsorption Desorption ◽  
Nitridation Temperature ◽  
Mcm 41

Titanium oxynitride and molybdenum oxynitride assembled in the pores of mesoporous materials were achieved by nitriding titania-modified MCM-41 and molybdena-modified MCM-41 at 800°C for 3 hours under flowing NH3 atmosphere. XRD, XPS and N2 adsorption-desorption isotherms were employed to characterize the structure of the composite materials. The results showed that the nanosized TiOxNy and MoOxNy particles were assembled in mesoporous silica MCM-41 with the restrict mesopores. The hexagonal periodicity of the parent MCM-41 materials was maintained upon assembly at the provided nitridation temperature. The exact formation was TiO0.4N0.8 in MCM-TiOxNy, and MoO1.7N0.57 in MCM-MoOxNy, which were calculated from the data in XPS spectra of Ti 2p and Mo 3d.

Ammoxidation of 3-Picoline over V2O5/TiO2 Catalysts: Effects of TiO2 Supports on the Catalytic Performance

2011 ◽  
Vol 396-398 ◽  
pp. 791-797 ◽  
Author(s):  
Fu Min Zhang ◽  
Fei Chen ◽  
Qiang Xiao ◽  
Yi Jun Zhong ◽  
Wei Dong Zhu
Keyword(s):  
Catalytic Properties ◽  
External Surface ◽  
Weak Interactions ◽  
Catalytic Performance ◽  
Vanadium Oxides ◽  
Active Species ◽  
Direct Oxidation ◽  
N2 Adsorption ◽  
Wet Impregnation ◽  
Adsorption Desorption

A series of V2O5/TiO2catalysts were prepared by wet impregnation, and these prepared catalysts were characterized by XRD, N2 adsorption-desorption, H2-TPR, and TEM techniques and used in the selective ammoxidation of 3-picoline to 3-cyanopyridine. The effects of TiO2 supports on the catalytic properties of the resulting catalysts for the ammoxidation of 3-picoline to 3-cyanopyridine were investigated in detail. It is found that the V5+/V4+ transformation during ammoxidation is more favorable than the V5+/V3+ transformation for the selective ammoxidation of 3-picoline to 3-cyanopyridine. The V2O5/TiO2catalysts prepared from the nanosized TiO2particles as supports show a high activity for the direct oxidation of 3-picoline by air, resulting Subscript text Subscript textin a low selectivity for 3-cyanopyridine. This could be due to the fact that the active species vanadium oxides could be only supported on the external surface of the nano-sized TiO2particles with very minor contact area, leading to the weak interactions between active species and support.

Biosorption of crystal violet dye using inactive biomass of the fungus Diaporthe schini

2019 ◽  
Vol 79 (4) ◽  
pp. 709-717 ◽  
Author(s):  
Patrícia Grassi ◽  
Caroline Reis ◽  
Fernanda C. Drumm ◽  
Jordana Georgin ◽  
Denise Tonato ◽  
...  
Keyword(s):  
Crystal Violet ◽  
X Ray Diffraction ◽  
N2 Adsorption ◽  
Biosorption Capacity ◽  
X Ray ◽  
Crystal Violet Dye ◽  
Endothermic Process ◽  
Desorption Isotherms ◽  
Adsorption Desorption ◽  
Scanning Electron

Abstract An inactive biomass of a new fungus recently discovered, Diaporthe schini, was evaluated for the biosorption of crystal violet (CV) in simulated textile effluents. The characterization assays were performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and N2 adsorption/desorption isotherms. The influences of pH and biosorbent dosage on the biosorption capacity were evaluated. Kinetics, equilibrium and thermodynamic studies were also carried out. Characterization techniques showed an amorphous biosorbent, with a rough surface containing irregular particles and surface area of 6.5 m2 g−1. The most adequate values of pH and biosorbent dosage were 7.5 and 0.4 g L−1, respectively. The Elovich kinetic model and the Sips equilibrium model were suitable to fit the experimental data. The biosorption capacity increased with temperature, reaching a maximum biosorption capacity of 642.3 mg g−1 at 328 K. The biosorption was a spontaneous and endothermic process. Diaporthe schini inactive biomass was an interesting biosorbent to treat colored effluents, presenting efficiency of 87% in the decolorization of a simulated dye house effluent.

Adsorptive removal of Rhodamine B from aqueous solution by nanoporous polydivinylbenzene

2017 ◽  
Vol 75 (7) ◽  
pp. 1651-1658 ◽  
Author(s):  
Hongyu Jia ◽  
Ningning Liu
Keyword(s):  
Rhodamine B ◽  
Adsorption Process ◽  
Order Model ◽  
N2 Adsorption ◽  
Adsorptive Removal ◽  
Langmuir Isotherm Model ◽  
Pseudo Second Order ◽  
Desorption Isotherms ◽  
Adsorption Desorption ◽  
Scanning Electron

Nanoporous polydivinylbenzene (PDVB) material has been successfully prepared via the copolymerization of divinylbenzene monomers. The nanoporous PDVB was characterized through N2 adsorption/desorption isotherms, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The nanoporous PDVB as an adsorbent was applied for the removal of Rhodamine B (RhB). The adsorption behavior of PDVB for the removal of RhB showed that the isotherm data followed the Langmuir isotherm model and the kinetic adsorption obeyed the pseudo-second-order model. Thermodynamic parameters illustrated that the adsorption process was spontaneous and exothermic. Interestingly, the spent nanoporous PDVB has excellent regenerative performance through treating it with ethanol. These results revealed that PDVB might be an excellent adsorbent for the removal of RhB from wastewater.

scholarly journals Influence of the synthesis conditions on the characteristics and metal adsorption properties of the 3-(1,4-phenylenediamine)propylsilica xerogel

2005 ◽  
Vol 30 (4) ◽  
pp. 43-49 ◽  
Author(s):  
J. C. P Vaghetti ◽  
J. L. Brasil ◽  
T. M. H Costa ◽  
E. C. Lima ◽  
E.V Benvenutti
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Aqueous Solution ◽  
Adsorption Properties ◽  
Metal Adsorption ◽  
N2 Adsorption ◽  
Organic Precursor ◽  
Synthesis Conditions ◽  
Desorption Isotherms ◽  
Adsorption Desorption

The hybrid 3-(1,4-phenylenediamine)propylsilica xerogel was obtained starting from two different organic precursor quantity (5 and 8 mmol) to 22 mmol of TEOS, in the synthesis. The xerogel samples were characterized by using CHN elemental analysis, N2 adsorption-desorption isotherms, infrared thermal analysis. The xerogel was used as metal sorbent for Cu2+, Cd2+ and Pb2+ in aqueous solution with concentration range of 10-3 to 10-5 mmol l-1. The quantity of organic precursor added in the synthesis influences the characteristics of the xerogel as morphology and thermal stability, as well as the metal adsorption capacity.

Influence of Synthesis Condition on N2 Adsorption Characteristics of Anatase TiO2 Particles Prepared in an Aqueous Solution

2008 ◽  
Vol 388 ◽  
pp. 103-106
Author(s):  
Yoshitake Masuda ◽  
Kazumi Kato
Keyword(s):  
Aqueous Solution ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Anatase Tio2 ◽  
N2 Adsorption ◽  
Tio2 Particles ◽  
Bet Specific Surface Area ◽  
Desorption Isotherms ◽  
Adsorption Desorption

TiO2 was crystallized to form particles in aqueous solutions containing ammonium hexafluorotitanate and boric acid. XRD diffraction patterns indicated they were in a single phase of anatase TiO2. TiO2 particles prepared at 90 °C exhibited N2 adsorption-desorption isotherms of type IV. BET specific surface area of the particles was estimated to 13 m2/g. On the other hand, TiO2 particles prepared at 50 °C exhibited N2 adsorption-desorption isotherms of type I. BET specific surface area of the particles was estimated to 168 m2/g. Crystal growth of TiO2 was strongly affected by synthesis temperature. Nano-sized pores or surface structure of TiO2 particles prepared at 50 °C would increase N2 adsorption volume to realize high BET specific surface area. Additionally, aqueous solution process described here had an advantage that TiO2 crystallized at ambient temperature. Anatase TiO2 was prepared without annealing at high temperature which caused aggregation of particles and disappearance of surface nanostructures. The particles with large surface area can be thus utilized for catalyst, cosmetic, photocatalyst, dye-sensitized solar cell or sensors.

scholarly journals A water soluble 3-n-propyl-1-azonia-4-azabicyclo[2.2.2]octanechloride silsesquioxane grafted onto Al/SiO2 surface: chromium adsorption study

2006 ◽  
Vol 31 (2) ◽  
pp. 53-58 ◽  
Author(s):  
L. T. Arenas ◽  
N. M. Simon ◽  
Y. Gushikem ◽  
T. M. H. Costa ◽  
E. C. Lima ◽  
...  
Keyword(s):  
Silica Surface ◽  
Water Soluble ◽  
N2 Adsorption ◽  
Adsorption Study ◽  
Chromium Vi ◽  
Grafting Reaction ◽  
Chromium Adsorption ◽  
Desorption Isotherms ◽  
Adsorption Desorption ◽  
Soluble Material

The water soluble material, 3-n-propyl-1-azonia-4-azabicyclo[2.2.2]octanechloride silsesquioxane (dabcosil silsesquioxane) was obtained. The dabcosil silsesquioxane was grafted onto a silica surface, previously modified with aluminum oxide. The resulting solid, dabcosil-Al/SiO2, presents 0.15 mmol of dabco groups per gram of material. The product of the grafting reaction was analyzed by infrared spectroscopy and N2 adsorption-desorption isotherms. The dabcosil-Al/SiO2 material was used as sorbent for chromium (VI) adsorption in aqueous solution.

Preparation of Silver Metallic Sponge from Macroporous Carbon Template

2006 ◽  
Vol 510-511 ◽  
pp. 770-773
Author(s):  
Jia Yan ◽  
An Jie Wang ◽  
Dong Pyo Kim
Keyword(s):  
Heat Dissipation ◽  
Reduction Reaction ◽  
Bet Surface Area ◽  
Borohydride Reduction ◽  
N2 Adsorption ◽  
Carbon Template ◽  
Desorption Isotherms ◽  
Porous Silver ◽  
Adsorption Desorption ◽  
Macroporous Carbon

Silver-containing porous frameworks have been extensively used in catalysis, electrochemistry, for heat dissipation and biofiltration. In this study, porous silver sponge was prepared by using a sacrificial macroporous carbon template. Aqueous AgNO3 was infiltrated into the carbon template and reduced to Ag by borohydride reduction reaction, followed by burning of the sacrificial template in air at 500~650°C. The products were characterized by SEM, XRD, and N2 adsorption-desorption isotherms. The Ag sponge exhibited a BET surface area of 12 m2/g.

Synthesis and Characterization of Stable Mesoporous Multilamellar Silica Vesicles

2007 ◽  
Vol 121-123 ◽  
pp. 473-478 ◽  
Author(s):  
Yu Fang Zhu ◽  
Jian Lin Shi ◽  
Wei Hua Shen
Keyword(s):  
Pore Volume ◽  
Specific Area ◽  
Synthesis And Characterization ◽  
N2 Adsorption ◽  
Structure Directing Agent ◽  
Large Pore Volume ◽  
Desorption Isotherms ◽  
Adsorption Desorption ◽  
High Specific Area

A family of mesoporous multilamellar silica vesicles has been successfully synthesized by using P123 as structure directing agent and hexane as co-surfactant. The structure was characterized with XRD, TEM, and N2 adsorption-desorption isotherms. This multilamellar silica vesicle materials process high specific area, large pore volume, and a bimodale pore size distribution. Furthermore, these materials are stable when the surfactant is removed at 530 oC.

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