scholarly journals Study on Photocatalytic Desulfurization and Denitrification Performance of Cu- and Cr-Modified MWCNT

Processes ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1823
Author(s):  
Yi Sun ◽  
Weiwei Jian ◽  
Siqi Tong ◽  
Danzhu Ma ◽  
Bohan Zhuang ◽  
...  

Carbon nanotubes are a promising adsorbent for desulfurization and denitrification. In this paper, Cu- and Cr-doped TiO2 supported by multi-walled carbon nanotubes (MWCNTs/Cu-Cr-TiO2) were synthesized by the sol-gel method. Characterizations of the samples were performed by TEM, XPS, XRD, DRS, and BET. The experiments of simultaneous desulfurization and denitrification were conducted in a fixed-bed reactor. The results showed that the adsorbent with a Cu to Cr molar ratio of 3 displays excellent adsorption property. The SO2 and NO adsorption capacity of MWCNTs/Cu-Cr-TiO2 (Cu/Cr = 3) were 36.83 and 12.34 mg/g under the optimal experimental operating parameters (SO2 content: 1575 mg/m3, NO content 736 mg/m3, O2 content 8%, H2O content 5%, and space velocity 1003 h−1). The adsorption capacity of MWCNTs/Cu-Cr-TiO2 was significantly better than that of the adsorbent doped with Cu or Cr alone (MWCNTs/Cu-TiO2 and MWCNTs/Cr-TiO2). Compared with single metal doping, bimetallic multivalent states accelerate the electron migration and separation from holes, which increase the number of oxygen vacancies and enhance the adsorption of SO2 and NO. The kinetic models and the reaction mechanism of the desulfurization and denitrification were also analyzed in this work.

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 321
Author(s):  
Yen-Ling Chen ◽  
Chin-Fang Juang ◽  
Yen-Cho Chen

The hydrogen production from ammonia decomposition on commercial 5 wt.% Ru/C (C: activated carbon) catalyst with different cesium (Cs) loadings at lower temperatures of 325–400 °C in the fixed-bed reactor was experimentally investigated. Based on the parameters used in this work, the results showed that the ammonia conversion at 350 °C is increased with the increasing Cs/Ru molar ratio, and it reaches its maximum value at the Cs/Ru molar ratio of 4.5. After that, it is rapidly decreased with a further increase of Cs/Ru molar ratio, and it is even smaller than that of the pure Ru/C case at the Cs/Ru molar ratio of 6. The Cs promotion at the lower Cs/Ru molar ratios may be due to the so-called “hot ring promotion”. The possible mechanisms for Cs effects on the ammonia conversion at higher Cs/Ru molar ratio are discussed. At optimum Cs loading, the results showed that all the ammonia conversions at 400 °C are near 100% for the GHSV (gas hourly space velocity) from 48,257 to 241,287 mL/(h·gcat).


Author(s):  
Venkateswara Rao Surisetty ◽  
Janusz Kozinski ◽  
Ajay K. Dalai

The effects of operating conditions on the higher alcohols synthesis reaction from synthesis gas were studied in a single-pass tubular downflow fixed-bed reactor, using sulfided K-promoted trimetallic Co-Rh-Mo catalyst supported on multi-walled carbon nanotubes (MWCNTs). The p CO conversion increased monotonically with increasing reaction temperature (from 275 to 350°C) and pressure (from 800 to 1400 psi), while decreasing monotonically with increasing GHSV (from 2.4 to 4.2 m3 (STP)/(kg of cat./h)). To maximize the ethanol STY and selectivity, the optimum operating conditions were determined as 330°C, 1320 psi, and 3.8 m3 (STP)/kg of cat./h). Maximum ethanol STY and selectivity were obtained using gas with H2 to CO molar ratio around 1.25.


Catalysts ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 24 ◽  
Author(s):  
Jeremías Martínez ◽  
Edgar Hernández ◽  
Salvador Alfaro ◽  
Ricardo López Medina ◽  
Guadalupe Valverde Aguilar ◽  
...  

In this work, we present an investigation concerning the evaluation of the catalytic properties of Ni nanoparticles supported on ZrO2, SiO2, and MgAl2O4 for CO2 hydrogenation to methane. The supports were prepared by coprecipitation and sol-gel, while Ni was incorporated by impregnation (10–20 wt %). X-ray diffraction, nitrogen physisorption, temperature-programmed reduction, H2 pulse chemisorption, Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy were the main characterization techniques employed. A laboratory fixed-bed reactor operated at atmospheric pressure, a temperature range of 350–500 °C, and a stoichiometric H2/CO2 molar ratio was used for catalyst evaluation. The most outstanding results were obtained with nickel catalysts supported on ZrO2 with CO2 conversions of close to 60%, and selectivity to methane formation was 100% on a dry basis, with high stability after 250 h of reaction time. The majority presence of tetragonal zirconia, as well as the strong Ni–ZrO2 interaction, were responsible for the high catalytic performance of the Ni/ZrO2 catalysts.


2021 ◽  
Vol 9 (2) ◽  
pp. 105110
Author(s):  
Y. Huaccallo-Aguilar ◽  
S. Álvarez-Torrellas ◽  
M. Larriba ◽  
V.I. Águeda ◽  
J.A. Delgado ◽  
...  

2018 ◽  
Vol 916 ◽  
pp. 139-143 ◽  
Author(s):  
Noor Asmawati Mohd Zabidi ◽  
Tuan Syahylah Tuan Sulong ◽  
Sardar Ali

CO2 conversion into valuable chemicals is an attractive option to deal with the increasing CO2 concentration in the atmosphere. In this study, Cu/ZnO catalyst was synthesized on multi-walled carbon nanotubes (MWCNTs) and Al2O3 supports via incipient wetness impregnation method. The physicochemical properties of the catalysts were investigated using TEM, XRD, N2 adsorption-desorption analysis, H2-TPR and XPS. The performance of the synthesized catalysts in a CO2 hydrogenation reaction was evaluated in a fixed-bed reactor at 503 K, 22.5 bar and H2:CO2 ratio of 3:1. TEM images showed that Cu/ZnO nanoparticles were deposited inside the CNTs as well as on the exterior walls of the CNTs. The average CuO crystallite size on Al2O3 and CNTs supports was 15.7 and 11 nm, repectively. Results of H2-TPR studies showed that the reducibility of the catalyst was improved on the CNTs support. XPS analysis confirmed the presence of Cu2+ in the samples, however, the binding energy of Cu 2p3/2 peak on the Al2O3 support was shifted to higher value compared to that of CNTs support. Products obtained from the CO2 hydrogenation reaction in the presence of these catalyts were methanol, ethanol, methyl formate and methane. The CO2 conversion of around 23% was obtained using both types of catalysts, however, Cu/ZnO on CNTs resulted in higher yield of methyl formate compared to that of Al2O3-supported catalyst.


2017 ◽  
Vol 68 (7) ◽  
pp. 1496-1500
Author(s):  
Rami Doukeh ◽  
Mihaela Bombos ◽  
Ancuta Trifoi ◽  
Minodora Pasare ◽  
Ionut Banu ◽  
...  

Hydrodesulphurization of dimethyldisulphide was performed on Ni-Co-Mo /�-Al2O3 catalyst. The catalyst was characterized by determining the adsorption isotherms, the pore size distribution and the acid strength. Experiments were carried out on a laboratory echipament in continuous system using a fixed bed catalytic reactor at 50-100�C, pressure from 10 barr to 50 barr, the liquid hourly space velocity from 1h-1 to 4h-1 and the molar ratio H2 / dimethyldisulphide 60/1. A simplified kinetic model based on the Langmuir�Hinshelwood theory, for the dimethyldisulphide hydrodesulfurization process of dimethyldisulphide has been proposed. The results show the good accuracy of the model.


2019 ◽  
Vol 20 (5) ◽  
pp. 390-400 ◽  
Author(s):  
Nabil N. AL-Hashimi ◽  
Amjad H. El-Sheikh ◽  
Rania F. Qawariq ◽  
Majed H. Shtaiwi ◽  
Rowan AlEjielat

Background: The efficient analytical method for the analysis of nonsteroidal antiinflammatory drugs (NSAIDs) in a biological fluid is important for determining the toxicological aspects of such long-term used therapies. Methods: In the present work, multi-walled carbon nanotubes reinforced into a hollow fiber by chitosan sol-gel assisted-solid/ liquid phase microextraction (MWCNTs-HF-CA-SPME) method followed by the high-performance liquid chromatography-diode array detection (HPLC–DAD) was developed for the determination of three NSAIDs, ketoprofen, diclofenac, and ibuprofen in human urine samples. MWCNTs with various dimensions were characterized by various analytical techniques. The extraction device was prepared by immobilizing the MWCNTs in the pores of 2.5 cm microtube via chitosan sol-gel assisted technology while the lumen of the microtube was filled with few microliters of 1-octanol with two ends sealed. The extraction device was operated by direct immersion in the sample solution. Results: The main factors influencing the extraction efficiency of the selected NSAIDs have been examined. The method showed good linearity R2 ≥ 0.997 with RSDs from 1.1 to 12.3%. The limits of detection (LODs) were 2.633, 2.035 and 2.386 µg L-1, for ketoprofen, diclofenac, and ibuprofen, respectively. The developed method demonstrated a satisfactory result for the determination of selected drugs in patient urine samples and comparable results against reference methods. Conclusion: The method is simple, sensitive and can be considered as an alternative for clinical laboratory analysis of selected drugs.


Author(s):  
Radwa A. El-Salamony ◽  
Sara A. El-Sharaky ◽  
Seham A. Al-Temtamy ◽  
Ahmed M. Al-Sabagh ◽  
Hamada M. Killa

Abstract Recently, because of the increasing demand for natural gas and the reduction of greenhouse gases, interests have focused on producing synthetic natural gas (SNG), which is suggested as an important future energy carrier. Hydrogenation of CO2, the so-called methanation reaction, is a suitable technique for the fixation of CO2. Nickel supported on yttrium oxide and promoted with cobalt were prepared by the wet-impregnation method respectively and characterized using SBET, XRD, FTIR, XPS, TPR, and HRTEM/EDX. CO2 hydrogenation over the Ni/Y2O3 catalyst was examined and compared with Co–Ni/Y2O3 catalysts, Co% = 10 and 15 wt/wt. The catalytic test was conducted with the use of a fixed-bed reactor under atmospheric pressure. The catalytic performance temperature was 350 °C with a supply of H2:CO2 molar ratio of 4 and a total flow rate of 200 mL/min. The CH4 yield was reached 67%, and CO2 conversion extended 48.5% with CO traces over 10Co–Ni/Y2O3 catalyst. This encourages the direct methanation reaction mechanism. However, the reaction mechanism over Ni/Y2O3 catalyst shows different behaviors rather than that over bi-metal catalysts, whereas the steam reforming of methane reaction was arisen associated with methane consumption besides increase in H2 and CO formation; at the same temperature reaction.


Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 224 ◽  
Author(s):  
Jung-Eun Park ◽  
Yong-Seok Jang ◽  
Tae-Sung Bae ◽  
Min-Ho Lee

Multi walled carbon nanotubes-hydroxyapatite (MWCNTs-HA) with various contents of MWCNTs was synthesized using the sol-gel method. MWCNTs-HA composites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). HA particles were generated on the surface of MWCNT. Produced MWCNTs-HA nanocomposites were coated on pure titanium (PT). Characteristic of the titanium coated MWCNTs-HA was evaluated by field-emission scanning electron microscopy (FE-SEM) and XRD. The results show that the titanium surface was covered with MWCNTs-HA nanoparticles and MWCNTs help form the crystalized hydroxyapatite. Furthermore, the MWCNTs-HA coated titanium was investigated for in vitro cellular responses. Cell proliferation and differentiation were improved on the surface of MWCNT-HA coated titanium.


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