KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Search Results

Now showing 1 - 9 of 9

Some of the metrics are blocked by your
consent settings
Valorization of eggshell waste to metal-doped CaO catalysts for producing dimethyl carbonate by transesterification of propylene carbonate with methanol
(2026-05-01)
Seeharaj, Panpailin
;
Werupho, Sakila
;
Puyamsai, Araya
;
Choengchan, Nathawut
;
Kim-Lohsoontorn, Pattaraporn
To align with a circular economy, this study aimed to extend the lifecycle of eggshell waste by valorizing it into a catalyst for producing the green chemical dimethyl carbonate (DMC) through the transesterification of propylene carbonate (PC) with methanol. CaO derived from eggshells was modified by doping with 10 mol% of aliovalent metal cations, including Na+, Mg2+, and Ce3+, via a calcination-hydration-dehydration process. The catalyst activity was tested under atmospheric air at 40–70 °C for 1–3 h. Metal-doped CaO possessed better activity than pure CaO, and the performance was ranked in order as CaO < Na–CaO < Ce–CaO < Mg–CaO. At the optimized reaction conditions of 50 °C for 2 h, the Mg–CaO catalyst exhibited the best performance, with 77% PC conversion, 62% DMC selectivity, and 37% DMC yield. This improvement correlated with the high surface-active area and optimum basicity induced by incorporating Mg2+ into the CaO structure and forming MgO–CaO mixed oxide phases. This study demonstrated a greener process for producing DMC under mild conditions using metal-doped CaO catalysts derived from eggshell waste.
Some of the metrics are blocked by your
consent settings
Correlation of urea precipitation temperature with phase formation, morphology, and catalytic activity for CO2 conversion of CeO2
(2025-08-01)
Seeharaj, Panpailin
;
Duangtanon, Jenjira
;
Sreemueang, Chanakan
;
Noppharat, Phetchphalin
;
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.
Some of the metrics are blocked by your
consent settings
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
;
Kim-Lohsoontorn, Pattaraporn
;
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.
Some of the metrics are blocked by your
consent settings
Alkanolamine-Grafted and Copper-Doped Titanium Dioxide Nanosheets-Graphene Composite Heterostructure for CO2 Photoreduction
(2023-11-13)
Karawek, Apisit
;
Kitjanukit, Nutkamol
;
Neamsung, Wannisa
;
Kinkaew, Chonlathon
;
Phadungbut, Poomiwat
CO<inf>2</inf> photoreduction is an intriguing approach to carbon capture, utilization, and storage (CCUS). It relies on an effective photocatalyst to generate photoinduced electrons that incorporate carbon dioxide (CO<inf>2</inf>), yielding fuel products, e.g., methane, methanol, and ethanol. The heterostructure of titanium dioxide nanosheets (TNS) and graphene oxide (GO) is a sandwich-type composite consisting of two 2-dimensional nanostructures (2D-2D). It was demonstrated as an excellent candidate for CO<inf>2</inf> photoreduction due to its outstanding charge separation ability. This research studied the photoactivity of alkanolamine-grafted TNS and alkanolamine-grafted and copper-doped TNS/GO composites. In the first experiment, triethanolamine-grafted TNS (TEA-TNS) exhibited the best ability in CO<inf>2</inf> photoreduction compared to monoethanolamine- and diethanolamine-grafted TNS (MEA-TNS and DEA-TNS) due to the base-catalyzed hydration nature of CO<inf>2</inf>-TEA interactions. In the second experiment, we studied the photoactivity of four composites, including copper-doped TNS/GO (Cu-TNS/GO), TEA-[Cu-TNS/GO] (grafting TEA on Cu-TNS/GO), Cu-[TEA-TNS]/GO (doping Cu on TEA-TNS/GO), and TEA-Cu-TNS/GO (one-step hydrothermal synthesis with the Cu precursor, TEA, and GO). TEA-[Cu-TNS/GO] showed the best photoactivity since TEA was added last to the heterostructures, which benefited in avoiding side chelation reactions between TEA and Cu ions and ensuring TEA exposure to CO<inf>2</inf>
Some of the metrics are blocked by your
consent settings
Improvement of surface properties of metal doped-CeO2 nanospindle catalysts for direct synthesis of dimethyl carbonate from CO2 and methanol
(2023-06-01)
Seeharaj, Panpailin
;
Saenman, Thanita
;
Phiwhom, Thanabat
;
Muangsuwan, Chutanan
;
Srinives, Sira
To utilize carbon dioxide (CO<inf>2</inf>) which is the main greenhouse gas, this study developed effective metal doped-CeO<inf>2</inf> nanospindle catalysts for conversion of CO<inf>2</inf> and methanol into dimethyl carbonate (DMC). Ce<inf>0.9</inf>M<inf>0.1</inf>O<inf>2</inf> nanospindles (where M is a transition metal, i.e., Zr, Fe, Cu and Co) were prepared by a template-free hydrothermal method. The substitution of different valence and size cations, including Zr4+, Fe3+, Cu2+ and Co2+, for Ce4+ sites in the fluorite CeO<inf>2</inf> lattice induced the defect formation of surface-active sites of exposed Ce3+ and oxygen vacancies through the charge compensation and redox pair reactions. Ce<inf>0.9</inf>Fe<inf>0.1</inf>O<inf>2</inf> solid solution with well-preserved spindle shaped morphology showed the highest catalytic performance by giving DMC yield at 3.56 mmol.g<inf>cat</inf>−1 with 100% DMC selectivity. The improvement of catalytic activity was attributed to the higher proportion of surface defect sites and variation of acid-base properties caused by the integration of Fe dopants into CeO<inf>2</inf> ionic system.
Some of the metrics are blocked by your
consent settings
Ultrasonically assisted surface modified CeO2 nanospindle catalysts for conversion of CO2 and methanol to DMC
(2022-11-01)
Kulthananat, Tachatad
;
Kim-Lohsoontorn, Pattaraporn
;
Seeharaj, Panpailin
This study developed a facile and effective approach to engineer the surface properties of cerium oxide (CeO<inf>2</inf>) nanospindle catalysts for the direct synthesis of dimethyl carbonate (DMC) from CO<inf>2</inf> and methanol. CeO<inf>2</inf> nanospindles were first prepared by a simple precipitation method followed by wet chemical redox etching with sodium borohydride (NaBH<inf>4</inf>) under high intensity ultrasonication (ultrasonic horn, 20 kHz, 150 W/cm2). The ultrasonically assisted surface modification of the CeO<inf>2</inf> nanospindles in NaBH<inf>4</inf> led to particle collisions and surface reduction that resulted in an increase in the number of surface-active sites of exposed Ce3+ and oxygen vacancies. The surface modified CeO<inf>2</inf> nanospindles showed an improvement of catalytic activity for DMC formation, yielding 17.90 mmol·g<inf>cat</inf>−1 with 100 % DMC selectivity. This study offers a simple and effective method to modify a CeO<inf>2</inf> surface, and it can further be applied for other chemical activities.
Some of the metrics are blocked by your
consent settings
Soft template-assisted copper-doped sodium dititanate nanosheet/graphene oxide heterostructure for photoreduction of carbon dioxide to liquid fuels
(2022-08-26)
Lertthanaphol, Napat
;
Prawiset, Natthanicha
;
Soontornapaluk, Pornpinun
;
Kitjanukit, Nutkamol
;
Neamsung, Wannisa
Photoreduction of CO<inf>2</inf> to a high-value product is an interesting approach that not only captures CO<inf>2</inf> but also converts it into other products that can be sold or used in industry. The mechanism for the CO<inf>2</inf> conversion relies strongly on photo-generated electrons that further couple with CO<inf>2</inf> and form active radicals for the reaction. In this research, we synthesized a heterostructure of copper-doped sodium dititanate nanosheets and graphene oxide (CTGN) following a one-step hydrothermal process with assistance from a sodium hydroxide soft template. The role of the template here is to facilitate the formation of the nanosheets, creating the nanosheet-graphene 2D-2D heterostructure. The heterostructure yields excellent charge mobility and a low charge recombination rate, while the nanosheet-graphene interfaces house active radicals and stabilize intermediates. The CTGN exhibits an outstanding photoactivity in the photoreduction of CO<inf>2</inf>, producing liquid fuels, including acetone, methanol, ethanol and i-propanol.
Some of the metrics are blocked by your
consent settings
One-Step Hydrothermal Synthesis of Precious Metal-Doped Titanium Dioxide–Graphene Oxide Composites for Photocatalytic Conversion of CO2 to Ethanol
(2021-12-28)
Lertthanaphol, Napat
;
Pienutsa, Natpichan
;
Chusri, Kittapas
;
Sornsuchat, Thirawit
;
Chanthara, Prowpatchara
We utilized a one-step hydrothermal process for the synthesis of precious metal-doped titanium dioxide (TiO<inf>2</inf>)/graphene oxide (GO) composites. The metal-doped TiO<inf>2</inf>/GO composites, including silver–TiO<inf>2</inf>/GO (Ag–TiO<inf>2</inf>/GO), palladium–TiO<inf>2</inf>/GO (Pd–TiO<inf>2</inf>/GO), and copper–TiO<inf>2</inf>/GO (Cu–TiO<inf>2</inf>/GO), were synthesized by mixing a metal precursor, titanium butoxide, and graphene oxide in a water–ethanol mixture in an autoclave hydrothermal reactor. The photocatalytic performance of the composites was tested in the photoreduction of carbon dioxide (CO<inf>2</inf>) to ethanol. Ag–TiO<inf>2</inf>/GO, Pd–TiO<inf>2</inf>/GO, and Cu–TiO<inf>2</inf>/GO exhibited an ethanol production rate of 109, 125, and 233 μmol/g<inf>cat</inf> h, respectively. The outstanding performances of Cu–TiO<inf>2</inf>/GO can be attributed to a combined effect of key parameters, including optical band gap, crystallite size, and BET surface area.
Some of the metrics are blocked by your
consent settings
CeO2/CuO/TiO2heterojunction photocatalysts for conversion of CO2to ethanol
(2021-09-10)
Seeharaj, Panpailin
;
Vittayakorn, Naratip
;
Morris, John
;
Kim-Lohsoontorn, Pattaraporn
An attempt to reduce CO2 emissions has led to the development of CeO2/CuO/TiO2 heterojunction photocatalysts for photoconversion of CO2 to useful products, e.g. ethanol. Composite photocatalysts were simply prepared by mixing TiO2 (P25) with different mass ratios of CeO2 (1 wt%) and CuO (2 or 3 wt%) by ball milling. The prepared photocatalysts had uniformly distributed CeO2 and CuO phases, throughout the TiO2 phase. The integration of CeO2 and CuO into TiO2 at 1 wt% CeO2 and 3 wt% CuO produced a composite, with a reduced band gap of 2.88 eV, allowing absorption of lower energy light and a lower electron-hole recombination rate. The 1%CeO2/3%CuO/TiO2 photocatalysts yielded ethanol at 30.5 μmol gcat-1 h-1, almost three times higher than the yield from pure TiO2. This improved CO2 conversion efficiency was due to contributions from properties of both additives: CeO2 increased light absorption, while CuO acted as an electron trap and enhanced CO2 adsorption. In addition, the heterojunction at the interfaces facilitated the photogenerated charge separation, which, in turn, increased the charge participation in the catalyzed conversion reactions.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results