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Correlation of urea precipitation temperature with phase formation, morphology, and catalytic activity for CO2 conversion of CeO2
(2025-08-01)
Seeharaj, Panpailin
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Duangtanon, Jenjira
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Sreemueang, Chanakan
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Noppharat, Phetchphalin
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Kulthananat, Tachatad
This study proposes a simple method for tailoring the morphology and activity of cerium oxide (CeO<inf>2</inf>) catalysts in converting carbon dioxide (CO<inf>2</inf>) and methanol to green organic carbonate, dimethyl carbonate (DMC), to utilize and reduce CO<inf>2</inf> emissions. CeO<inf>2</inf> was prepared by urea precipitation at 85, 105, and 125 °C for 2 h, then calcining at 600 °C for 2 h. The phase structure and morphology of CeO<inf>2</inf> correlated with the urea hydrolysis rate. A low degree of supersaturation at 85 °C led to heterogeneous precipitation of cerium oxycarbonate (Ce<inf>2</inf>O(CO<inf>3</inf>)<inf>2</inf>.H<inf>2</inf>O) and CeO<inf>2</inf> with spherical morphology, while a higher degree of supersaturation at 105 °C and 125 °C resulted in homogeneous precipitation of single-phase Ce<inf>2</inf>O(CO<inf>3</inf>)<inf>2</inf>.H<inf>2</inf>O with spindle and elongated octahedral morphology, respectively. The spindle-shaped CeO<inf>2</inf> prepared at 105 °C with a predominant surface (111) facet showed the highest catalytic activity, with a DMC yield of 18.81 mmol.g<inf>cat</inf>−1. The enhanced catalytic efficiency of spindle-shaped CeO<inf>2</inf> was due to the high concentration of surface-active defect sites of exposed cerium cations and oxygen vacancies, which optimized the number of acid–base sites in adsorbing and activating CO<inf>2</inf> and methanol to produce DMC.
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Modification of acid–base properties of metal-doped ZnO catalysts for the transesterification of propylene carbonate with methanol to dimethyl carbonate
(2025-04-01)
Ieamviteevanich, Pimchanok
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Kim-Lohsoontorn, Pattaraporn
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Seeharaj, Panpailin
This study investigated the effect of metal dopants on the surface properties of ZnO-based catalysts for the transesterification of propylene carbonate (PC) with methanol to produce dimethyl carbonate (DMC). A series of metal-doped ZnO nanocatalysts (M-ZnO, where M is Ca2+, Cu2+, Ce3+, La3+, and Y3+ with the mol ratio of Zn2+/Mx+ = 4) were prepared by a simple co-precipitation method followed by calcining in air at 673 K for 5 h. Introducing different metal cations into the ZnO system decreased crystallite size and created surface defects of exposed cations and oxygen vacancies, increasing surface-active acid and basic sites. The catalytic performance for DMC production was ranked as follows: Ca-ZnO < Cu–ZnO < ZnO < Ce-ZnO < Y-ZnO < La-ZnO. La-ZnO showed the highest performance of all catalysts, with 67% PC conversion, 67% DMC selectivity, and 45% DMC yield. The improvement of catalytic activity was correlated with an increase in the concentration of moderate and strong acid–base functionalities on the La-ZnO surfaces for participating in the reaction of PC and methanol to form DMC.
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Fe2O3-graphene anchored Ag nanocomposite catalyst for enhanced sonocatalytic degradation of methylene blue
(2021-05-01)
Noypha, Amnuay
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Areerob, Yonrapach
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Chanthai, Saksit
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Nuengmatcha, Prawit
In the present research work, Fe<inf>2</inf>O<inf>3</inf>-graphene-Ag (FGA) was synthesized by a simple hydrothermal method. The sonocatalytic activity of the FGA particles was evaluated by the degradation of methylene blue (MB) under ultrasonic irradiation, revealing their good sonocatalytic activity. The effects of various experimental factors, such as dosage, time, and ultrasonic frequencies on the sonocatalytic efficiency were investigated; a significant influence of different factors on the sonocatalytic degradation of MB was observed, whereas the best degradation conditions were obtained when ultrasonic irradiation was performed for 90 min at room temperature considering MB concentration = 0.5 g L−1, C<inf>catalyts</inf> = 1 g L−1, and pH 6.5. Moreover, the sonocatalytic activity of the FGA was compared to that of Fe<inf>2</inf>O<inf>3</inf> (F), graphene (G), and Fe<inf>2</inf>O<inf>3</inf>-graphene (FG). As a result, the FGA was found to exhibit higher sonocatalytic activity than other catalysts (FGA > FG > G > F), which evidenced the practical utility of the synthesized FGA as a highly effective catalyst for the removal of dye pollutants. Finally, the plausible sonocatalytic mechanism of FGA is also discussed in this work.
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Catalytic ozonation using iron-doped water treatment sludge as a catalyst for treatment of phenol in synthetic wastewater
(2019-04-01)
Sukmilin, Apiradee
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Boonchom, Banjong
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Jarusutthirak, Chalor
In this study, iron (Fe)-doped water treatment sludge, designated as Fe/WTS, was prepared by a hydrothermal method using phosphoric acid and impregnation with ferric nitrate. The results from X-ray diffraction (XRD) confirmed the presence of Fe loaded on the WTS support, while Brunauer-Emmett-Teller (BET) analysis indicated an increase of specific surface area of the WTS from 37.37 m2/g to 118.51 m2/g after acid modification. The Fe/WTS was successfully used as a catalyst in catalytic ozonation for degradation of phenol in synthetic wastewater. Factors affecting phenol removal efficiency including reaction time, pH, catalyst dosage, and Fe content were investigated. At the optimum condition, i.e., reaction time of 120 min, pH of 11, catalyst dosage of 1 g/L, and Fe content of 2% (w/w), the removal efficiency of phenol was 99.16% which was higher than that of sole ozonation (44.61%). The results of kinetic analyses indicated that the reactions of catalytic ozonation in the presence of Fe/WTS and WTS catalysts followed pseudo-first order kinetic model with rate constants of 0.0362 and 0.0065 min-1, respectively, while that of sole ozone was 0.0046 min-1. This finding presented the potential use of Fe/WTS as a novel catalyst for catalytic ozonation.
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Preparation of monometallic catalysts on carbon support for synthesis of biodiesel fuel
(2019-01-01)
Longprang, Tripob
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Udomsap, Parncheewa
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Chollacoop, Nuwong
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Fuji, Masayoshi
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Eiad-Ua, Apiluck
Monometallic catalysts have been prepared on nano-porous carbon support materials by way of hydrothermal carbonization of Cattail (genus Typha) leaves. The catalysts are for synthesis of biodiesel fuel. This research studied the effect of hydrothermal temperature (at 160-200 °C), reaction time (4-24 h) and the presence of KOH on the activated porosity of a carbon support. Then the type of loaded metal catalyst (Mn, Fe, Co, Ni, Cu and Pb), placed on the carbon support by an impregnation method, was investigated. This led to partial hydrogenation catalytic activity forming biodiesel. The carbonization temperature was studied in the range 500-900 °C for 2 hours. The samples were characterized by scanning electron microscopy, nitrogen sorption, fourier transform infrared spectroscopy and X-ray diffraction. The results indicated that the hydrothermal process at 200 °C for 12 hours exhibited the highest surface area, porosity and pore volume. This led to an appropriate distribution of metal on the carbon support surface.
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Photocatalysis of heat treated sodium- and hydrogen-titanate nanoribbons for water splitting, H2/O2 generation and oxalic acid oxidation
(2013-04-09)
Kiatkittipong, Kunlanan
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Iwase, Akihide
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Scott, Jason
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Amal, Rose
The photocatalytic activity of sodium titanate (Na<inf>1.48</inf>H<inf>0.52</inf>Ti<inf>3</inf>O<inf>7</inf>), sodium hexatitanate (Na<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf>), and hydrogen titanate (H<inf>2</inf>Ti<inf>3</inf>O<inf>7</inf>) nanoribbons and anatase TiO<inf>2</inf> nanorods were compared for water splitting, oxalic acid photodegradation and H<inf>2</inf> and O<inf>2</inf> generation using sacrificial agents. The intrinsic properties of the materials were found to affect their performance depending on the particular reaction system. The Na<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf> nanoribbons, in the presence of RuO<inf>2</inf> co-catalyst, outperformed the anatase nanorods, for the water splitting reaction, generating over 10 times more H<inf>2</inf>/O<inf>2</inf>. This was thought to derive from their tunnel-like structure which provided better electron/hole separation when compared with TiO<inf>2</inf>. However, the efficient holes and electrons scavenging in the presence of sacrificial agents, methanol or AgNO<inf>3</inf>, to generate H<inf>2</inf> or O<inf>2</inf>, respectively, overwhelmed the tunnel-like structure effect. In this case photoactivity was governed by the crystal structure, with observed decreasing activity in the order TiO<inf>2</inf>>Na<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf>>H<inf>2</inf>Ti<inf>3</inf>O<inf>7</inf>~Na<inf>1.48</inf>H<inf>0.52</inf>Ti<inf>3</inf>O<inf>7</inf>, and by the band gap of the semiconductor which determined its capacity to absorb photons in producing electron/hole pairs. © 2013 Elsevier Ltd.
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Synthesis of carbon nanotube and carbon nanofiber in nanopore of anodic aluminum oxide template by chemical vapor deposition at atmospheric pressure
(2012-10-15)
Kasi, Jafar Khan
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Kasi, Ajab Khan
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Wongwiriyapan, Winadda
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Afzulpurkar, Nitin
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Dulyaseree, Paweena
Carbon nanotube (CNT) is one of the most attractive materials for the potential applications of nanotechnology due to its excellent mechanical, thermal, electrical and optical properties. We demonstrated the fabrication of carbon nanotube and carbon nanofiber (CNF) inside the pore and at the surface of anodic aluminum oxide (AAO) membrane by chemical vapor deposition method at atmospheric pressure. Ethanol was used as a hydrocarbon source and Co-Mo as catalyst. CNT was synthesized at different temperature. High graphitic multiwall carbon nanotube (MWCNT) was found at 750°C, while CNF was found at 800oC and above temperature analyzing by Raman spectroscopy. © (2012) Trans Tech Publications, switzerland.

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