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1.
Small ; : e2406243, 2024 Oct 04.
Artículo en Inglés | MEDLINE | ID: mdl-39363796

RESUMEN

Anode materials storing large-scale lithium ions gradually decrease electrochemical performance due to severe volume changes during cycling. Therefore, there is an urgent need to develop anode materials with high electrochemical capacity and durability, without deterioration arising due to the volume changes during the electrochemical processes. To date, mesoporous materials have received attention as anode materials due to their ability to mitigate volume expansion, offer a short pathway for Li+ transport, and exhibit anomalous high capacity. However, the nano-frameworks of transition metal oxide collapse during conversion reactions, demanding an improvement in nano-framework structure stability. In this study, ordered mesoporous nickel manganese oxide (m-NMO) is designed as an anode material with a highly durable nanostructure. Interestingly, m-NMO showed better cycle performance and higher electrochemical capacity than those of nickel oxide and manganese oxide. Operando small-angle X-ray scattering and ex situ transmission electron microscopic results confirmed that the binary m-NMO sustained a highly durable nanostructure upon cycling, unlike the single metal oxide electrodes where the mesostructures collapsed. Ex situ X-ray absorption spectroscopy proved that nickel and manganese showed different electrochemical reaction voltages, and thus undergoes sequential conversion reactions. As a result, both elements can act as complementary nano-propping buffers to maintain stable mesostructure.

2.
Dalton Trans ; 53(36): 15284-15296, 2024 Sep 18.
Artículo en Inglés | MEDLINE | ID: mdl-39222328

RESUMEN

In this study, a catalyst composite of Co-Cu was prepared from chloride-containing precursor of Co(II) and Cu(II) metals using the milky latex of the Euphorbia neriifolia plant following green principles of synthesis. The catalyst composite was characterized using XRD, EDAX, SEM, HR-TEM, FTIR, XPS and TOF-MS. The crystallinity of the mixed-oxide composite with a distorted octahedral nature was confirmed from analysis. Chemical charge analysis of the Co-Cu mixed phase based on XPS revealed Co2+ and Cu2+ oxidation states. This material was used for synthesizing 2,4,5-triaryl-1H-imidazole (TIMDZOL) derivatives. Analysis of reaction conditions revealed that EtOH : PEG at 8 : 2 ratio under microwave conditions showed better yields with less time and better reusability of the Co-Cu catalyst.

3.
Medicine (Baltimore) ; 102(46): e35994, 2023 Nov 17.
Artículo en Inglés | MEDLINE | ID: mdl-37986344

RESUMEN

The purpose of this study is to analyze the publicness of medical services in public and private medical institutions, with a focus on treatment performance using National Health Insurance data. Data from the National Health Insurance Service were used to compare the publicness of medical services in public and private medical institutions. Beta regression analysis was conducted after adjusting for the relevant characteristics to identify the impact on the public treatment performance of medical institutions. The public case rate of public health institutions was higher than that of private medical institutions. According to the type of medical care institution, the public case rate was higher in general hospitals and tertiary hospitals than in hospitals. Recently, it has often highlighted that increasing emphasis of profitability in the evaluation of public health institutions is damaging the publicness of medical services. Even in this study, it can be evaluated that the public case rate of public health institutions is not higher than that of private medical institutions.


Asunto(s)
Programas Nacionales de Salud , Salud Pública , Humanos , Hospitales Públicos , Instituciones de Salud , Seguro de Salud
4.
Materials (Basel) ; 16(19)2023 Oct 08.
Artículo en Inglés | MEDLINE | ID: mdl-37834735

RESUMEN

This study describes the single-step synthesis of a mesoporous layered nickel-chromium-sulfide (NCS) and its hybridization with single-layered graphene oxide (GO) using a facile, inexpensive chemical method. The conductive GO plays a critical role in improving the physicochemical and electrochemical properties of hybridized NCS/reduced GO (NCSG) materials. The optimized mesoporous nanohybrid NCSG is obtained when hybridized with 20% GO, and this material exhibits a very high specific surface area of 685.84 m2/g compared to 149.37 m2/g for bare NCS, and the pore diameters are 15.81 and 13.85 nm, respectively. The three-fold superior specific capacity of this optimal NCSG (1932 C/g) is demonstrated over NCS (676 C/g) at a current density of 2 A/g. A fabricated hybrid supercapacitor (HSC) reveals a maximum specific capacity of 224 C/g at a 5 A/g current density. The HSC reached an outstanding energy density of 105 Wh/kg with a maximum power density of 11,250 W/kg. A 4% decrement was observed during the cyclic stability study of the HSC over 5000 successive charge-discharge cycles at a 10 A/g current density. These results suggest that the prepared nanohybrid NCSG is an excellent cathode material for gaining a high energy density in an HSC.

5.
ACS Appl Mater Interfaces ; 15(26): 31393-31402, 2023 Jul 05.
Artículo en Inglés | MEDLINE | ID: mdl-37339373

RESUMEN

Active and nonprecious-metal bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are vital components of clean energy conversion devices such as regenerative fuel cells and rechargeable metal-air batteries. Porous manganese oxides (MnOx) are promising electrocatalyst candidates because of their high surface area and the abundance of Mn. MnOx catalysts exhibit various oxidation states and crystal structures, which critically affect their electrocatalytic activity. These effects remain elusive mainly because the synthesis of oxidation-state-controlled porous MnOx with similar structural properties is challenging. In this work, four different mesoporous manganese oxides (m-MnOx) were synthesized and used as model catalysts to investigate the effects of local structures and Mn valence states on the activity toward oxygen electrocatalysis. The following activity trends were observed: m-Mn2O3 > m-MnO2 > m-MnO > m-Mn3O4 for the ORR and m-MnO2 > m-Mn2O3 > m-MnO ≈ m-Mn3O4 for the OER. These activity trends suggest that high-valent Mn species (Mn(III) and Mn(IV)) with disordered atomic arrangements induced by nanostructuring significantly influence electrocatalysis. In situ X-ray absorption spectroscopy was used to analyze the changes in the oxidation states under the ORR and OER conditions, which showed the surface phase transformation and generation of active species during electrocatalysis.

6.
Luminescence ; 38(5): 625-636, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-36929164

RESUMEN

The present investigation deals with the effect of calcination temperature on the structural and thermoluminescent (TL) properties of Zn2 SiO4 materials. For this study, Zn2 SiO4 was prepared via a simple hydrothermal route and calcinated at temperatures from 700°C to 1100°C in an air atmosphere. TL data of all Zn2 SiO4 samples showed two peaks at around 240°C and 330°C due to the formation of the luminescence centre during X-ray irradiation. More interestingly, the Zn2 SiO4 sample calcinated at 900°C exhibited a shift in the TL peak (282°C and 354°C) with an optimal TL intensity attributed to its good crystallinity with a well-defined hexagonal plate-like morphology. X-ray-irradiated Zn2 SiO4 samples calcinated at 900°C exhibited a high-temperature TL glow curve peak, suggesting that the present material could be used for high-temperature dosimetry applications.


Asunto(s)
Luminiscencia , Zinc , Temperatura , Rayos X , Dosimetría Termoluminiscente , Difracción de Rayos X
7.
Anal Methods ; 15(2): 171-178, 2023 Jan 06.
Artículo en Inglés | MEDLINE | ID: mdl-36504026

RESUMEN

Surface chemistry of electrodes plays a critical role in the fields of electrochemistry and electric-field-assisted separation. In this study, making ingenious use of the ordered mesoporous structure of silica materials and the electrochemical stability of ionic liquids (ILs) when integrated with polyvinylpyrrolidone (PVP), the PVP-modified IL-mesoporous silica/platinum wire (Pt/PVP@meso-SiO2@IL) was fabricated to increase hydroelectric stability and avoid the problem of electrode polarization. The effect of different amounts of mesoporous silica material used to modify the surface of the Pt electrode was systematically investigated. As a result, we successfully obtained a highly ordered mesoporous Pt/PVP@meso-SiO2 material with smooth surface. Because pentyl triethylamine bis(trifluoromethylsulfonyl) imide exhibits a wide electrochemical window between -3 to 3 V, this IL was chosen to modify mesopores under vacuum. Even after repeatedly applying electric field on Pt/PVP@meso-SiO2@IL 100 times, this working electrode remained stable and showed high hydroelectric stability. After verifying the feasibility of this method, it was successfully applied in the electric-field-assisted separation of 2.0 and 3.0 µm polystyrene particles without any impediment from electrode polarization problems. This work provides a brand-new insight for resolving the problem of electrode polarization by developing a versatile tool for the electroseparation of micro-objects.

8.
ACS Nano ; 16(1): 631-642, 2022 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-35029370

RESUMEN

Iron oxide anode materials for rechargeable lithium-ion batteries have garnered extensive attention because of their inexpensiveness, safety, and high theoretical capacity. Nanostructured iron oxide anodes often undergo negative fading, that is, unconventional capacity increase, which results in a capacity increasing upon cycling. However, the detailed mechanism of negative fading still remains unclear, and there is no consensus on the provenance. Herein, we comprehensively investigate the negative fading of iron oxide anodes with a highly ordered mesoporous structure by utilizing advanced synchrotron-based analysis. Electrochemical and structural analyses identified that the negative fading originates from an optimization of the electrolyte-derived surface layer, and the thus formed layer significantly contributes to the structural stability of the nanostructured electrode materials, as well as their cycle stability. This work provides an insight into understanding the origin of negative fading and its influence on nanostructured anode materials.

9.
Medicine (Baltimore) ; 100(50): e28362, 2021 Dec 17.
Artículo en Inglés | MEDLINE | ID: mdl-34918716

RESUMEN

ABSTRACT: A growing number of people depend on flexible employment, characterized by outsider employment and lower levels of job security. This study investigated whether there was a synergistic effect of employment status and job insecurity on mental disorders.This study used data from the 2012 Canadian Community Health Survey-Mental Health (CCHS) of 13,722 Canada's labor force population aged 20 to 70. Data were collected from January to December, 2012, using computer-assisted personal interviewing. As combining employment status with perceived job insecurity, we formed five job categories: secure full-time, full-time insecure, part-time secure, part-time insecure employment, and unemployment.Results showed that, regardless of employment status (full-time vs part-time), insecure employment was significantly associated with high risk of mental disorders. Furthermore, the odds ratios for insecure employment were similar to those for unemployment. Male workers who are full-time, but with insecure jobs, were more likely to experience mental disorders than female workers.This study's findings imply that while perceived job insecurity may be a critical factor for developing mental health problems among workers, providing effective health care services can mitigate an excessive health risk for the most vulnerable employment, especially for insecure part-time employment and unemployment.


Asunto(s)
Empleo , Trastornos Mentales/epidemiología , Salud Mental , Desempleo/psicología , Adulto , Canadá/epidemiología , Empleo/psicología , Empleo/estadística & datos numéricos , Femenino , Estado de Salud , Conducta de Búsqueda de Ayuda , Humanos , Masculino , Trastornos Mentales/etiología , Trastornos Mentales/psicología , Persona de Mediana Edad , Salud Pública
10.
Chem Commun (Camb) ; 57(81): 10500-10503, 2021 Oct 12.
Artículo en Inglés | MEDLINE | ID: mdl-34580686

RESUMEN

The movement of the sulfur species of a lithium-sulfur battery cathode was directly observed through pioneering operando SAXS analysis. Micropore is a prior repository for sulfur before and after the electrochemical reaction. Mesopore is actual reaction site for sulfur species. The separate properties of the pores were established, adding critical insight to advanced carbon cathode material design.

11.
RSC Adv ; 11(44): 27453-27460, 2021 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-35480669

RESUMEN

The oxidative desulfurization (ODS) of organic sulfur compounds over tungsten oxide supported on highly ordered mesoporous SnO2 (WO x /meso-SnO2) was investigated. A series of WO x /meso-SnO2 with WO x contents from 10 wt% to 30 wt%, were prepared by conventional wet impregnation. The physico-chemical properties of the WO x /meso-SnO2 catalysts were characterized by X-ray diffraction (XRD), N2 adsorption-desorption isotherms, electron microscopy, Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and the temperature-programmed reduction of hydrogen (H2-TPR). The characterization results indicated that these catalysts possessed mesoporous structures with uniform pores, high specific surface areas, and well-dispersed polyoxotungstate species on the surface of meso-SnO2 support. The ODS performances were evaluated in a biphasic system (model oil/acetonitrile, S initial = 2000 ppm), using H2O2 as an oxidant, and acetonitrile as an extractant. Dibenzothiophene (DBT) in the model oil was removed completely within 60 min at 50 °C using 20 wt% WO x /meso-SnO2 catalyst. Additionally, the effect of reaction temperature, H2O2/DBT molar ratio, amount of catalyst and different sulfur-containing substrates on the catalytic performances were also investigated in detail. More importantly, the 20 wt% WO x /meso-SnO2 catalyst exhibited 100% surfur-removal efficiency without any regeneration process, even after six times recycling.

12.
Lab Chip ; 20(19): 3535-3543, 2020 09 29.
Artículo en Inglés | MEDLINE | ID: mdl-32852497

RESUMEN

An open-tubular radially cyclical electric field-flow fractionation technique which achieves the online separation of microparticles in a functional annular channel is proposed in this study. The system was set up by using a stainless steel tube and a platinum wire modified with ionic liquid/mesoporous silica materials as the external and internal electrodes. The feasibility for online separation of various particles was experimentally demonstrated. Particles in the channel were affected by a radial electric field and field-flow fractionation (FFF). On the cross section, different particles showed distinctive migration distances depending on their own properties and the different magnitudes of forces being exerted. The same kind of particles form an annular distribution within the same annulus while different particles form annular distributions at varied concentric annuli through electrophoresis. Under a laminar flow of FFF, different sizes of particles formed a conical arrangement within the annular separation channel. With the joint influence of electric field and flow field, different trajectories were obtained and the particles were eventually separated. Voltage, frequency and duty cycle value are the main parameters affecting the separation of particles. By adjusting these parameters, particles migrate in a zigzag trajectory on one side of the electrodes (mode I) and reach both sides of the electrodes (mode II). Six polystyrene particles were completely separated with high resolution within several minutes. Our system offers numerous advantages of label-free, high-resolution and online separation without tedious operations, and it is a promising tool for the effective separation of various micro-objects.

13.
Small ; 16(1): e1905868, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31788955

RESUMEN

Beyond a traditional view that metal nanoparticles formed upon electrochemical reaction are inactive against lithium, recently their electrochemical participations are manifested and elucidated as catalytic and interfacial effects. Here, ruthenium metal composed of ≈5 nm nanoparticles is prepared and the pure ruthenium as a lithium-ion battery anode for complete understanding on anomalous lithium storage reaction mechanism is designed. In particular, the pure metal electrode is intended for eliminating the electrochemical reaction-derived Li2 O phase accompanied by catalytic Li2 O decomposition and the interfacial lithium storage at Ru/Li2 O phase boundary, and thereby focusing on the ruthenium itself in exploring its electrochemical reactivity. Intriguingly, unusual lithium storage not involving redox reactions with electron transfer but leading to lattice expansion is identified in the ruthenium electrode. Size-dependent charge redistribution at surface enables additional lithium adsorption to occur on the inactive but more environmentally sensitive nanoparticles, providing innovative insight into dynamic electrode environments in rechargeable lithium chemistry.

14.
Healthcare (Basel) ; 8(1)2019 Dec 19.
Artículo en Inglés | MEDLINE | ID: mdl-31861601

RESUMEN

Because the high-cost of medical imaging can cause a tremendous economic burden across the health care system, we investigated factors associated with taking additional computed tomography (CT) scans. Data of gastric cancer patients were eligible for analysis if the patient underwent a gastrectomy during the study period (2002-2013). We defined initial CT scans as those taken within 90 days from the surgery date. If there was an additional CT scan between the date of an initial CT scan and the surgery date, we regarded it as a reexamination. We used multivariate logistic regression analysis for reexamination CT scans. Among 3342 gastrectomy patients, 1165 participants underwent second CT scans. Transfer experience (adjusted odds ratio (OR) = 23.87, 95% confidence interval (CI) = 18.15-31.39) was associated with higher OR for reexamination. Among transferred patients, an increased number per 100 beds at the initial CT hospital was associated with a decreased OR for reexamination (OR = 0.88, 95% CI = 0.83-0.94), but increased beds in surgery hospitals was related to an increased OR for reexamination (OR = 1.29, 95% CI = 1.20-1.36). In our study, transfer experience, initial CT scan in a low-volume hospital, and surgical treatment in a high-volume hospital were associated with reexamination CT scans.

15.
Asia Pac J Public Health ; 31(6): 499-509, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-31516035

RESUMEN

The purpose of this study was to determine whether the introduction of diagnosis-related groups (DRGs) shifted the medical services from inpatient to outpatient settings. Using a difference-in-difference analysis, the changes in length of stay, outpatient visit days within 30 days before hospitalization, and outpatient visit days within 30 days after hospital discharge were evaluated. The length of stay was reduced after the DRG policy, consistent with previous studies. Outpatient visit days within 30 days before a hospital admission increased significantly after the policy change. In addition, outpatient visit days within 30 days after a hospital discharge increased in all the medical institutions excluding hospitals. The study findings are consistent with the expectation that providers respond to changes in the payment system to protect or enhance their economic interests. Health care providers in Korea responded to the DRG policy by reducing the intensity of inpatient treatment and transferring costs to outpatient settings.


Asunto(s)
Atención Ambulatoria/estadística & datos numéricos , Grupos Diagnósticos Relacionados , Hospitalización/estadística & datos numéricos , Humanos , Revisión de Utilización de Seguros , Tiempo de Internación/estadística & datos numéricos , República de Corea
16.
Environ Res ; 172: 649-657, 2019 05.
Artículo en Inglés | MEDLINE | ID: mdl-30878736

RESUMEN

The catalytic oxidation of toluene with ozone at room temperature was carried out over hierarchically ordered mesoporous catalysts (CeO2 (meso), Mn2O3 (meso), ZrO2 (meso), and γ-Al2O3 (meso)) and Al2O3 with various textural properties and phases (γ-Al2O3 (meso), γ-Al2O3 (13 nm), and α-Al2O3) to examine the effects of the nature of the catalyst on the catalytic activity. The catalysts were characterized by N2-physisorption measurements, powder X-ray diffraction, temperature programmed reduction, X-ray photoelectron spectroscopy and scanning transmission electron microscopy with energy dispersive spectroscopy. Among the ordered mesoporous catalysts, γ-Al2O3 (meso) had the highest toluene removal efficiency because of its highest surface area and pore volume, which in turn was selected for further investigation. Manganese (Mn) was introduced to various Al2O3 to improve the toluene removal efficiency. Comparing the Mn-loaded catalysts supported on various Al2O3 with different crystalline phases or pore structures, Mn/γ-Al2O3 (meso), had the highest catalytic activity as well as the highest CO2/CO ratio. The higher activity was attributed to the larger surface area, weaker interaction between Mn and Al2O3, and larger portion of Mn2O3 phase. The increase in ozone concentration led to an improvement in the carbon balance but this enhancement was insufficient due to the deposition of by-products on the catalyst. After long term tests at room temperature, the reaction intermediates and carbonaceous deposits of the used catalysts were identified.


Asunto(s)
Técnicas de Química Analítica , Ozono , Tolueno , Óxido de Aluminio/química , Catálisis , Técnicas de Química Analítica/métodos , Manganeso/química , Ozono/química , Temperatura , Tolueno/aislamiento & purificación
17.
Artículo en Inglés | MEDLINE | ID: mdl-30577514

RESUMEN

Background: This study researched related causes that make scheduled surgeries canceled not to be conducted and based on the research it is to derive issues in order to reduce surgery cancellation. Methods: We analyzed the association of surgery cancellation with patient characteristics, surgical characteristics and surgery schedule related characteristics, using electronic medical record (EMR) data on surgeries conducted at a university hospital in Korea over 10 years. Additionally, we examined the reasons for surgery cancellation based on patient and hospital characteristics. We used chi-square tests to analyze the distribution of various characteristics according to reasons for surgery cancellation. Multivariate logistic regression analyses were conducted to evaluate the factors associated with surgery cancellation. Results: Among 60,333 cases, surgery cancellation rate was 8.0%. The results of the logistic regression indicated a high probability of surgery cancellation when the patient was too old (odds ratio [OR]: 1.35, 95% confidence interval [CI]: 1.14⁻1.59), when it was a neurosurgery case (OR: 1.39, 95% CI: 1.21⁻1.59), when local anesthesia was used (OR: 1.15, 95% CI: 1.07⁻1.24) or when it was a planned surgery (OR: 2.45, 95% CI: 2.21⁻2.73). The surgery cancellation rate was lower when the patient was female (OR: 0.87, 95% CI: 0.82⁻0.93) or when the surgery was related to Obstetrics & Gynecology (OR: 0.53, 95% CI: 0.46⁻0.60) or Ophthalmology (OR: 0.66, 95% CI: 0.56⁻0.79). Among the canceled 4834 cases, the surgery cancellation rate for the reasons of patients was 93.2% and the surgery cancellation rate for the reasons of a hospital was 6.8%. Conclusions: This study found that there are related various causes to cancel operations, including patient characteristics, surgery related characteristics and surgery schedule related characteristics and it means that it would be possible for some reasons to be prevented. Every medical institution should consider the operation cancellation as an important issue and systematic monitoring should be needed.


Asunto(s)
Hospitales Generales/estadística & datos numéricos , Hospitales Universitarios/estadística & datos numéricos , Pacientes Desistentes del Tratamiento/estadística & datos numéricos , Procedimientos Quirúrgicos Operativos/estadística & datos numéricos , Adolescente , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Procedimientos Quirúrgicos Electivos/estadística & datos numéricos , Registros Electrónicos de Salud , Femenino , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Embarazo , República de Corea , Factores Sexuales , Factores Socioeconómicos , Adulto Joven
18.
ACS Appl Mater Interfaces ; 10(35): 29992-29999, 2018 Sep 05.
Artículo en Inglés | MEDLINE | ID: mdl-30088911

RESUMEN

It is widely accepted that solid electrolyte interphase (SEI) layer of carbonaceous material is formed by irreversible decomposition reaction of an electrolyte, and acts as a passivation layer to prevent further decomposition of the electrolyte, ensuring reliable operation of a Li-ion battery. On the other hand, recent studies have reported that some transition metal oxide anode materials undergo reversible decomposition of an organic electrolyte during cycling, which is completely different from carbonaceous anode materials. In this work, we revisit the electrochemical reaction of an electrolyte that produces SEI layer on the surface of carbonaceous anode materials using soft X-ray absorption spectroscopy. We discover that the reversible formation and decomposition of SEI layer are also able to occur on the carbonaceous materials in both Li- and Na-ion battery systems. These new findings on the unexpected behavior of SEI in the carbonaceous anode materials revealed by soft X-ray absorption spectroscopy would be highly helpful in more comprehensive understanding of the interfacial chemistry of carbonaceous anode materials in Li- and Na-ion batteries.

19.
J Nanosci Nanotechnol ; 18(1): 353-358, 2018 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-29768853

RESUMEN

Ordered mesoporous Cu-Mn binary metal oxide (meso-CuMnOx) catalysts were successfully synthesized by a hard-templating method from a mesoporous silica template with a cubic Ia3d mesostructure (KIT-6) or hydrophobic KIT-6, exhibiting a well-developed crystalline framework, a regular pore size distribution and a high surface area. The copper and manganese elements in the mesoporous Cu-Mn binary metal oxides (meso-CuMnOx-N and meso-CuMnOx-HP), obtained from the KIT-6 and hydrophobic KIT-6, respectively, were homogeneously dispersed in the whole particles. The activities of meso-CuMnOx catalysts for the decomposition of a liquid monopropellant containing an energetic ionic liquid, ammonium dinitramide, were much higher than that over a CuMnOx catalyst prepared by a conventional precipitation method. This is attributed to the well-developed mesoporosity of the meso-CuMnOx catalysts. Among the mesoporous CuMnOx catalysts, the decomposition onset temperature over meso-CuMnOx-HP (87.9 °C) was found to be lower than that over meso-CuMnOx-N (100.4 °C), probably due to its higher mesoporosity and surface area.

20.
J Nanosci Nanotechnol ; 18(9): 6300-6303, 2018 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-29677785

RESUMEN

The thermal and catalytic pyrolysis of Pinus densiflora (P. densiflora) were performed to test the catalytic cracking efficiency of two mesoporous Al2O3 catalysts with different surface areas. Thermogravimetric analysis (TGA) of P. densiflora showed that the differential TG (DTG) peak heights obtained from catalytic pyrolysis were smaller than those of non-catalytic pyrolysis due to the conversion of the reaction intermediates to coke. Pyrolyzer-gas chromatography/mass spectrometry analysis/flame ionization detection (Py-GC/MS/FID) suggested that using the Al2O3 catalysts, the yields of phenols and levoglucosan decreased with a concomitant increase in the yields of aldehydes, alcohol, ketones, and furans. Between the two catalysts, Al2O3-B prepared by spray pyrolysis showed higher cracking efficiency than Al2O3-A prepared by hydrothermal method because of its larger surface area.

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