scholarly journals Altered Properties of TiO2 for Photocatalytic Oxidative Desulphurisation

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Che Ku Nor Liana Che Ku Hitam ◽  
Aishah Abdul Jalil
Keyword(s):  
Band Gap ◽  
High Surface ◽  
High Surface Area ◽  
Band Gap Energy ◽  
Energy Usage ◽  
Reaction Conditions ◽  
Electrolysis Method ◽  
Visible Irradiation ◽  
Carrier Separation ◽  
Adsorption Desorption

Photocatalytic oxidative desulphurisation has become a promising technique as a result of its high capability, mild reaction conditions, economical, and low energy usage. In the present study, copper oxide doped on titanium dioxide (CuO/TiO2) was prepared by facile electrolysis method. The presence of mesoporous materials with high surface area was confirmed by nitrogen (N2) adsorption-desorption analysis where the band gap energies were determined by ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS). The photoactivity testing on desulphurisation of 100 mg L-1 dibenzothiophene (DBT) revealed the highest extraction (7.5 x 10-3 mM min-1) and photooxidation rates (1.8 x 10-3 mM min-1), which were acquired by 0.8 g L-1 Cu0.1T0.9 after 2 h under visible irradiation. This is attributed by the well dispersion of CuO on TiO2, suitable band gap energy, and better charge carrier separation by the synergistic interaction of both materials.

scholarly journals Catalytic Transfer of Fructose to 5-Hydroxymethylfurfural over Bimetal Oxide Catalysts

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Qiuyun Zhang ◽  
Xiaofang Liu ◽  
Tingting Yang ◽  
Quanlin Pu ◽  
Caiyan Yue ◽  
...  
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
Direct Conversion ◽  
Significant Loss ◽  
Desorption Isotherm ◽  
High Yield ◽  
Reaction Conditions ◽  
Strong Acidity ◽  
Adsorption Desorption

Direct conversion of fructose into 5-hydroxymethylfurfural (HMF) is achieved by using modified aluminum-molybdenum mixed oxide (S-AlMo) as solid acid catalysts. The synthesized catalyst was characterized by powder XRD, nitrogen adsorption-desorption isotherm, NH3-TPD, and SEM. As a result, the presence of strong acidity, mesostructures, and high surface area in the S-AlMo catalyst was confirmed by nitrogen adsorption-desorption isotherm and NH3-TPD studies. A study by optimizing the reaction conditions such as catalyst dosage, reaction temperature, and time has been performed. Under the optimal reaction conditions, HMF was obtained in a high yield of 49.8% by the dehydration of fructose. Moreover, the generality of the catalyst is also demonstrated by glucose and sucrose with moderate yields to HMF (24.9% from glucose; 27.6% from sucrose) again under mild conditions. After the reaction, the S-AlMo catalyst can be easily recovered and reused four times without significant loss of its catalytic activity.

Texture Evaluation of Sol-Gel Derived Mesoporous Bioactive Glass

2013 ◽  
Vol 284-287 ◽  
pp. 230-234
Author(s):  
Yu Jen Chou ◽  
Chi Jen Shih ◽  
Shao Ju Shih
Keyword(s):  
Surface Area ◽  
Calcination Temperature ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
Bioactive Glasses ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Adsorption Desorption

Recent years mesoporous bioactive glasses (MBGs) have become important biomaterials because of their high surface area and the superior bioactivity. Various studies have reported that when MBGs implanted in a human body, hydroxyl apatite layers, constituting the main inorganic components of human bones, will form on the MBG surfaces to increase the bioactivity. Therefore, MBGs have been widely applied in the fields of tissue regeneration and drug delivery. The sol-gel process has replaced the conventional glasses process for MBG synthesis because of the advantages of low contamination, chemical flexibility and lower calcination temperature. In the sol-gel process, several types of surfactants were mixed with MBG precursor solutions to generate micelle structures. Afterwards, these micelles decompose to form porous structures after calcination. Although calcination is significant for contamination, crystalline and surface area in MBG, to the best of the authors’ knowledge, only few systematic studies related to calcination were reported. This study correlated the calcination parameters and the microstructure of MBGs. Microstructure evaluation was characterized by transmission electron microscopy and nitrogen adsorption/desorption. The experimental results show that the surface area and the pore size of MBGs decreased with the increasing of the calcination temperature, and decreased dramatically at 800°C due to the formation of crystalline phases.

Efficient and Reusable Silica Gel Supported Metal Ionic Liquid Catalysts for Palmitic Acid Esterification to Biodiesel

2021 ◽  
Vol 43 (1) ◽  
pp. 1-1
Author(s):  
Guo Yingwei Guo Yingwei ◽  
Chen Xuedan Chen Xuedan ◽  
Yan Shiting Yan Shiting ◽  
Zhang Zhengliang Zhang Zhengliang ◽  
Chen Yuqin Chen Yuqin ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Palmitic Acid ◽  
Silica Gel ◽  
High Surface ◽  
High Surface Area ◽  
Kinetic Studies ◽  
Catalytic Performance ◽  
Reaction Conditions ◽  
Acid Esterification ◽  
Supported Metal

A series of silica gel (SG) supported metal ionic liquid catalysts (x[Bmim]Cl-CrCl3/SG) were synthesized and exploited for the esterification of palmitic acid (PA) with methanol (ML) to produce biodiesel efficiently. The 10%[Bmim]Cl-CrCl3/SG catalyst with high surface area and desirable acidity exhibited the best catalytic performance and reusability after six consecutive running cycles. Based on the response surface analysis, the optimal reaction conditions were obtained as follows: methanol/acid mole ratio = 11:1 mol/mol, catalyst amount = 5.3 wt%, reaction time = 65 min, as well as reaction temperature = 373 K, reaching to a biodiesel yield of 96.1%. Further kinetic studies demonstrated that the esterification of PA with ML obeyed 1.41 order kinetics for acid concentration with the activation energy of 16.88 kJ/mol

scholarly journals Catalytic Activity of High-Surface-Area Amorphous MgO Obtained from Upsalite

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1338
Author(s):  
Marek Gliński ◽  
Ewa M. Iwanek (nee Wilczkowska) ◽  
Urszula Ulkowska ◽  
Agnieszka Czajka ◽  
Zbigniew Kaszkur
Keyword(s):  
Surface Area ◽  
Carbonyl Compounds ◽  
Main Product ◽  
High Surface ◽  
High Surface Area ◽  
Hydrogenation Reaction ◽  
Transfer Hydrogenation ◽  
Reaction Conditions ◽  
Synthesis Conditions ◽  
Transfer Hydrogenation Reaction

The first aim of the research was to synthesize a pure Upsalite, which is an amorphous form of MgCO3, by modifying a procedure described in the literature, so that it would be the precursor of a high-surface, amorphous magnesium oxide. The results indicate that within the studied reaction conditions, the type of alcohol used as the reactant has the most pronounced effect on the yield of reaction. From the two alcohols that led to the highest yield of Upsalite, methanol gave a substantially larger surface area (794 vs. 191 m2 g−1). The optimized synthesis conditions of Upsalite were used to obtain MgO via thermolysis, whose activity in the transfer hydrogenation reaction (THR) from ethanol, 2-propanol and 2-pentanol to various carbonyl compounds was determined. The optimal conditions for the thermolysis were as follows: vacuum, T = 673 K as the final temperature, and a heating rate of 2 deg min−1. The high-surface, amorphous magnesia (SBET = 488 m2 g−1) was found to be a very selective catalyst to 4-t-butylcyclohexanone in THR, which led to a diastereoselectivity of over 94% to the E-isomer of 4-t-butylcyclohexanol for more than 3 h, with conversions of up to 97% with either 2-propanol or 2-pentanol as the hydrogen donor. In the case of acrolein and 2-n-propylacrolein being used as the hydrogen acceptors, the unsaturated alcohol (UOL) was the main product of the reaction, with higher UOL yields noted for ethanol than 2-propanol.

Efficient and Reusable Silica Gel Supported Metal Ionic Liquid Catalysts for Palmitic Acid Esterification to Biodiesel

2021 ◽  
Vol 43 (1) ◽  
pp. 1-1
Author(s):  
Guo Yingwei Guo Yingwei ◽  
Chen Xuedan Chen Xuedan ◽  
Yan Shiting Yan Shiting ◽  
Zhang Zhengliang Zhang Zhengliang ◽  
Chen Yuqin Chen Yuqin ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Palmitic Acid ◽  
Silica Gel ◽  
High Surface ◽  
High Surface Area ◽  
Kinetic Studies ◽  
Catalytic Performance ◽  
Reaction Conditions ◽  
Acid Esterification ◽  
Supported Metal

A series of silica gel (SG) supported metal ionic liquid catalysts (x[Bmim]Cl-CrCl3/SG) were synthesized and exploited for the esterification of palmitic acid (PA) with methanol (ML) to produce biodiesel efficiently. The 10%[Bmim]Cl-CrCl3/SG catalyst with high surface area and desirable acidity exhibited the best catalytic performance and reusability after six consecutive running cycles. Based on the response surface analysis, the optimal reaction conditions were obtained as follows: methanol/acid mole ratio = 11:1 mol/mol, catalyst amount = 5.3 wt%, reaction time = 65 min, as well as reaction temperature = 373 K, reaching to a biodiesel yield of 96.1%. Further kinetic studies demonstrated that the esterification of PA with ML obeyed 1.41 order kinetics for acid concentration with the activation energy of 16.88 kJ/mol

scholarly journals No detectable aerobic methane efflux from plant material, nor from adsorption/desorption processes

2008 ◽  
Vol 5 (6) ◽  
pp. 1551-1558 ◽  
Author(s):  
M. U. F. Kirschbaum ◽  
A. Walcroft
Keyword(s):  
Zea Mays ◽  
High Surface ◽  
High Surface Area ◽  
Atmospheric Methane ◽  
Plant Materials ◽  
Methane Fluxes ◽  
Detached Leaves ◽  
Filter Papers ◽  
Adsorption Desorption ◽  
Methane Efflux

Abstract. In early 2006, Keppler et al. (Nature, 439:187–191) reported a novel finding that plant leaves, and even simple organic materials, can release methane under aerobic conditions. We investigated here whether the reported methane release might simply arise from methane desorption from sample surfaces after prior exposure to higher methane concentrations. We exposed standard cellulose filter papers (i.e. organic material with a high surface area) to atmospheric methane concentration and then transferred them to a low-methane atmosphere. Our results suggest that any desorption flux was extremely small (−0.0001±0.0019 ngCH4 kgDW−1 s−1) and would play no quantitatively significant role in modifying any measured methane fluxes. We also incubated fresh detached leaves of several species and intact Zea mays seedlings under aerobic and low-light conditions. After correcting for a small measured methane influx into empty chambers, measured rates of methane emission by plant materials were zero or, at most, very small, ranging from −0.25±1.1 ngCH4 kgDW−1 s−1 for Zea mays seedlings to 0.10±0.08 ngCH4 kgDW−1 s−1 for a mixture of freshly detached grasses. These rates were much smaller than the rates originally reported by Keppler et al. (2006).

scholarly journals Enzymatic Bioreactors: An Electrochemical Perspective

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1232
Author(s):  
Simin Arshi ◽  
Mehran Nozari-Asbemarz ◽  
Edmond Magner
Keyword(s):  
Direct Electron Transfer ◽  
High Surface ◽  
High Surface Area ◽  
Enzyme Engineering ◽  
Future Perspective ◽  
Enzymatic System ◽  
Reaction Conditions ◽  
Flow Reactors ◽  
Recent Developments ◽  
Enzyme Cascades

Biocatalysts provide a number of advantages such as high selectivity, the ability to operate under mild reaction conditions and availability from renewable resources that are of interest in the development of bioreactors for applications in the pharmaceutical and other sectors. The use of oxidoreductases in biocatalytic reactors is primarily focused on the use of NAD(P)-dependent enzymes, with the recycling of the cofactor occurring via an additional enzymatic system. The use of electrochemically based systems has been limited. This review focuses on the development of electrochemically based biocatalytic reactors. The mechanisms of mediated and direct electron transfer together with methods of immobilising enzymes are briefly reviewed. The use of electrochemically based batch and flow reactors is reviewed in detail with a focus on recent developments in the use of high surface area electrodes, enzyme engineering and enzyme cascades. A future perspective on electrochemically based bioreactors is presented.

Facile Fabrication of Single Crystalline Ceria Nanoparticles for Photo-Responsive Applications

2012 ◽  
Vol 734 ◽  
pp. 127-137
Author(s):  
D.P. Das ◽  
Armita Dash ◽  
B.K. Mishra
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Band Gap Energy ◽  
Ceria Nanoparticles ◽  
Processing Conditions ◽  
Hydrothermal Route ◽  
Single Crystalline ◽  
Nanocrystallite Size ◽  
Facile Fabrication

The present investigation is about fabrication of single-crystalline ceria (CeO2) nanoparticle by a hydrothermal route. High surface area CeO2 was synthesized with transformation of morphology from nanofibers to nanocubes in response to processing conditions. A steady variation of average nanocrystallite size ca. in the range 3.0-16.9 nm and a range of band gap energy from 2.6 to 2.9 eV were measured. The surface area of the nanoparticles varied in the range 16.0136.1 m2/g and the variation in surface area is attributed to the nature of packing of particles. The ceria nanofibers could generate 870.5 µmol of H2 in 3 h of irradiation.

Efficient Removal of Cd2+ by the Mesoporous Silica Functionalized by APTES

2013 ◽  
Vol 726-731 ◽  
pp. 2409-2412
Author(s):  
Xiao Feng Cai ◽  
Kang Wei Ji ◽  
Wan Hao Wu ◽  
Jie Hou ◽  
Shi You Hao
Keyword(s):  
Aqueous Solution ◽  
Mesoporous Silica ◽  
Ph Value ◽  
High Surface ◽  
High Surface Area ◽  
Efficient Removal ◽  
Structure Directing Agent ◽  
Functionalized Mesoporous Silica ◽  
Adsorption Desorption ◽  
Large Pore Size

Amino-functionalized mesoporous silica (AFMS) with high amino loading, high surface area, and large pore size was synthesized using the anionic surfactant N-lauroylsarcosine sodium (Sar-Na) as template and 3-aminopropyltriethoxysilane (APTES) as co-structure directing agent (CSDA). The synthesized AFMS was characterized by N2adsorption-desorption, TEM and elemental analyzer. The results of the removal of Cd2+from aqueous solution showed that the pH value of aqueous solution affected the removal efficiency of Cd2+greatly, and that unary adsorption isotherm of Cd2+on the AFMS was well described by the Sips isotherm model, in which the adsorption capacity was 2.43 mmol/g for Cd2+, much higher than the literature data.

scholarly journals Mesoporous CdO/Al2O3 nanocomposite with enhanced optoelectronic properties for visible-light photocatalysis and bactericidal applications

2021 ◽  
Author(s):  
Janani B ◽  
Asad Syed ◽  
Abdallah M. Elgorban ◽  
Ali H. Bahkali ◽  
S. Sudheer Khan
Keyword(s):  
Photoelectron Spectroscopy ◽  
Organic Contaminants ◽  
Dye Degradation ◽  
High Surface ◽  
High Surface Area ◽  
Energy Shift ◽  
Band Gap Energy ◽  
Oh Radicals ◽  
X Ray ◽  
Viable Solution

Abstract Pristine Al2O3 and CdO are known to possess poor photocatalytic activity individually. The formation of CdO/Al2O3 heterojunction was investigated for the enhancement of photocatalytic performance. High resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) has been used to determine the crystalline feature and elemental composition of the NCs respectively. Peaks ascribed to Cd-O and O-Al-O was noted in fourier-transform infrared spectroscopy (FTIR) analysis. The NCs exhibits a high surface area (27.23 m2/g) to their contributing particles which was analysed using BET analyser. The band gap energy of CdO/Al2O3NCs was observed to be 2.95 eV which shows a considerable energy shift from its individual particles, CdO (2.73 eV) and Al2O3 (3.94 eV). The results displayed that the degradation efficiency of the CdO-Al2O3 NCs was enhanced 14 times than pristine Al2O3 and 3.5 times than pristine CdO. The MB dye has showed the half life period of 80 min. TOC analysis of degraded product supported high mineralization of the pollutants. The dye degradation was driven by OH. radicals and the CdO-Al2O3 nanocomposite possessed high reusability which was confirmed by six cycle test. Growth inhibition of E. coli, P. aeruginosa and B. subtilis was attained by exposure to CdO/Al2O3 NCs. The CdO-Al2O3 NCs can be a viable solution for degradation of organic contaminants effectively under natural sun light as well as an efficient antibacterial agent.

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