scholarly journals PECULIARITIES OF SMALL STRAINED ALICYCLE COMPOUNDS FORMATION IN CATALYTIC TRANSFORMATION OF METHANOL OVER ZEOLITE H-ZSM-5

2018 ◽  
Vol 61 (12) ◽  
pp. 74-80
Author(s):  
Valentin Yu. Doluda ◽  
Alexey V. Bykov ◽  
Mikhail G. Sulman ◽  
Alexander I. Sidorov ◽  
Natalia V. Lakina ◽  
...  
Keyword(s):  
Reaction Temperature ◽  
Carbon Concentration ◽  
Photoelectron Spectroscopy ◽  
Feed Rate ◽  
Accumulation Rate ◽  
Formation Rate ◽  
Carbon Surface ◽  
Catalytic Transformation ◽  
X Ray ◽  
Methanol Feed Rate

The article presents the results of strained hydrocarbons formation study during the catalytic transformation of methanol into hydrocarbons on zeolite H-ZSM-5. The formation of the following strained cyclic compounds was determined: 1,1-dimethylcyclopropane, 1,2-dimethyl-cyclopropane, 1,1,2-trimethylcyclopropane, 1,2,3-trimethylcyclopropane, 1,1,2,2-tetramethylcyclo-propane, 1,1,2 , 3-tetramethylcyclopropane. The non-stationary character of strained cyclic hydrocarbons formation with a pronounced hydrocarbons formation rate maximum and subsequent deactivation of the catalyst was found. The temperature effect on strained hydrocarbons yield was evaluated. Thus, with an increase in the process reaction temperature up to 400 °C, a maximum of strained hydrocarbons accumulation rate was achieved as 8-8.5 g(Hyd)/(kg(Cat)·h) on 350 h of reaction, and a further increase in the reaction temperature leads to a decrease in the strained hydrocarbons accumulation rate. The effect of the methanol feed rate on the strained hydrocarbons formation rate was also studied. An increase in the methanol feed rate from 0.02 ml/min to 0.16 ml/min results in increase in the strained hydrocarbons formation rate up to 37 g (Hyd)/(kg(Cat)·h). The article presents results of H-ZSM-5 physicochemical study used by ammonia chemisorption, nitrogen phisisorption, X-ray photoelectron spectroscopy. Physicochemical studies of catalyst samples after the methanol transformation process to form strained hydrocarbons showed a twofold decrease in the number of acid sites from 1.2 mmol(NH3)/g (sample) to 0.3 mmol (NH3)/g(sample) and a significant decrease in surface area of micropores from 294 m2/g for the initial sample to 16 m2/g for the sample after the reaction. The X-ray diffraction spectroscopy method showed that the composition of the catalysts H-ZSM-5 surface includes carbon, oxygen, silicon and aluminum. Carbon concentration was found to be 4.3 at.% on the surface of the initial catalyst. While the carbon concentration increases up to 14.1 at.% during the reaction. Also oxygen content on the catalysts surface decreases from 59.9 to 53.4 at%, silica concentration decreases from 35.5 to 32.1 at.%. The following indicates the formation of a carbon surface layer over the catalysts.

scholarly journals Hydrothermal Activation of Porous Nitrogen-Doped Carbon Materials for Electrochemical Capacitors and Sodium-Ion Batteries

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2163 ◽  
Author(s):  
Yuliya V. Fedoseeva ◽  
Egor V. Lobiak ◽  
Elena V. Shlyakhova ◽  
Konstantin A. Kovalenko ◽  
Viktoriia R. Kuznetsova ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Carbon Nanomaterials ◽  
Carbon Materials ◽  
Sodium Ion ◽  
Carbon Surface ◽  
Energy Storage And Conversion ◽  
Sodium Ion Batteries ◽  
X Ray ◽  
Nitrogen Doped ◽  
Nitrogen Doped Carbon

Highly porous nitrogen-doped carbon nanomaterials have distinct advantages in energy storage and conversion technologies. In the present work, hydrothermal treatments in water or ammonia solution were used for modification of mesoporous nitrogen-doped graphitic carbon, synthesized by deposition of acetonitrile vapors on the pyrolysis products of calcium tartrate. Morphology, composition, and textural characteristics of the original and activated materials were studied by transmission electron microscopy, X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, infrared spectroscopy, and nitrogen gas adsorption method. Both treatments resulted in a slight increase in specific surface area and volume of micropores and small mesopores due to the etching of carbon surface. Compared to the solely aqueous medium, activation with ammonia led to stronger destruction of the graphitic shells, the formation of larger micropores (1.4 nm vs. 0.6 nm), a higher concentration of carbonyl groups, and the addition of nitrogen-containing groups. The tests of nitrogen-doped carbon materials as electrodes in 1M H2SO4 electrolyte and sodium-ion batteries showed improvement of electrochemical performance after hydrothermal treatments especially when ammonia was used. The activation method developed in this work is hopeful to open up a new route of designing porous nitrogen-doped carbon materials for electrochemical applications.

scholarly journals CO2 Methanation of Biogas over 20 wt% Ni-Mg-Al Catalyst: on the Effect of N2, CH4, and O2 on CO2 Conversion Rate

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1201
Author(s):  
Danbee Han ◽  
Yunji Kim ◽  
Hyunseung Byun ◽  
Wonjun Cho ◽  
Youngsoon Baek
Keyword(s):  
Reaction Temperature ◽  
Photoelectron Spectroscopy ◽  
Conversion Rate ◽  
Space Velocity ◽  
Molar Ratio ◽  
Co2 Conversion ◽  
X Ray Diffraction ◽  
Co2 Methanation ◽  
X Ray ◽  
Ch4 Production

Biogas contains more than 40% CO2 that can be removed to produce high quality CH4. Recently, CH4 production from CO2 methanation has been reported in several studies. In this study, CO2 methanation of biogas was performed over a 20 wt% Ni-Mg-Al catalyst, and the effects of CO2 conversion rate and CH4 selectivity were investigated as a function of CH4, O2, H2O, and N2 compositions of the biogas. At a gas hourly space velocity (GHSV) of 30,000 h−1, the CO2 conversion rate was ~79.3% with a CH4 selectivity of 95%. In addition, the effects of the reaction temperature (200–450 °C), GHSV (21,000–50,000 h−1), and H2/CO2 molar ratio (3–5) on the CO2 conversion rate and CH4 selectivity over the 20 wt% Ni-Mg-Al catalyst were evaluated. The characteristics of the catalyst were analyzed using Brunauer–Emmett–Teller surface area analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The catalyst was stable for approximately 200 h at a GHSV of 30,000 h−1 and a reaction temperature of 350 °C. CO2 conversion and CH4 selectivity were maintained at 75% and 93%, respectively, and the catalyst was therefore concluded to exhibit stable activity.

scholarly journals Preparation of Monoclinic Pyrrhotite by Thermal Decomposition of Jarosite Residues and Its Heavy Metal Removal Performance

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 267
Author(s):  
Cuimin Xu ◽  
Qiaoqin Xie ◽  
Fan Xu ◽  
Yuefei Zhou ◽  
Hanlin Wang ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Reaction Temperature ◽  
Photoelectron Spectroscopy ◽  
Metal Removal ◽  
Formation Rate ◽  
Heavy Metal Removal ◽  
Phase Evolution ◽  
The Core ◽  
Hydrometallurgical Processing ◽  
Monoclinic Pyrrhotite

Jarosite residues produced by zinc hydrometallurgical processing are hazardous solid wastes. In this study, monoclinic pyrrhotite (M­Po) was prepared by the pyrolysis of jarosite residues in H2S atmosphere. The influence of gas speed, reaction temperature, and time was considered. The mineral phase, microstructure, and elemental valence of the solids before and after pyrolysis were analyzed using X­ray diffraction, scanning electron microscopy, and X­ray photoelectron spectroscopy, respectively. The performances of the prepared M­Po on the removal of Zn and Pb from aqueous solution were evaluated. The results show M­Po to be the sole product at the reaction temperatures of 550 to 575 °C. Most of the M­Po particles are at the nanometer scale and display xenomorphic morphology. The phase evolution process during pyrolysis is suggested as jarosite → hematite/magnetite → pyrite → pyrite+M­Po → M­Po+hexagonal pyrrhotite (H­Po) → H­Po. The formation rate, crystallinity, and surface microtexture of M­Po are controlled by reaction temperature and time. Incomplete sulfidation may produce coarse particles with core–shell (where the core is oxide and the shell is sulfide) and triple-layer (where the core is sulfate, the interlayer is oxide, and the shell is sulfide) structures. M­Po produced at 575 °C exhibits an excellent heavy metal removal ability, which has adsorption capacities of 25 mg/g for Zn and 100 mg/g for Pb at 25 °C and pH ranges from 5 to 6. This study indicates that high-temperature sulfidation is a novel and efficient method for the treatment and utilization of jarosite residues.

scholarly journals Bactericides Based on Copper Nanoparticles Restrain Growth of Important Plant Pathogens

Pathogens ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1024
Author(s):  
Adamantia Varympopi ◽  
Anastasia Dimopoulou ◽  
Ioannis Theologidis ◽  
Theodora Karamanidou ◽  
Alexandra Kaldeli Kerou ◽  
...  
Keyword(s):  
Copper Nanoparticles ◽  
Photoelectron Spectroscopy ◽  
Xanthomonas Campestris ◽  
Plant Pathogens ◽  
Bacterial Resistance ◽  
Accumulation Rate ◽  
Low Cost ◽  
Attenuated Total Reflection ◽  
X Ray

Copper nanoparticles (CuNPs) can offer an alternative to conventional copper bactericides and possibly slow down the development of bacterial resistance. This will consequently lower the accumulation rate of copper to soil and water and lower the environmental and health burden imposed by copper application. Physical and chemical methods have been reported to synthesize CuNPs but their use as bactericides in plants has been understudied. In this study, two different CuNPs products have been developed, CuNP1 and CuNP2 in two respective concentrations (1500 ppm or 300 ppm). Both products were characterized using Dynamic Light Scattering, Transmission Electron Microscopy, Attenuated Total Reflection measurements, X-ray Photoelectron Spectroscopy, X-ray Diffraction and Scattering, and Laser Doppler Electrophoresis. They were evaluated for their antibacterial efficacy in vitro against the gram-negative species Agrobacterium tumefaciens, Dickeya dadantii, Erwinia amylovora, Pectobacterium carotovorum, Pseudomonas corrugata, Pseudomonas savastanoi pv. savastanoi, and Xanthomonas campestris pv. campestris. Evaluation was based on comparisons with two commercial bactericides: Kocide (copper hydroxide) and Nordox (copper oxide). CuNP1 inhibited the growth of five species, restrained the growth of P. corrugata, and had no effect in X. c. pv campestris. MICs were significantly lower than those of the commercial formulations. CuNP2 inhibited the growth of E. amylovora and restrained growth of P. s. pv. savastanoi. Again, its overall activity was higher compared to commercial formulations. An extensive in vitro evaluation of CuNPs that show higher potential compared to their conventional counterpart is reported for the first time and suggests that synthesis of stable CuNPs can lead to the development of low-cost sustainable commercial products.

scholarly journals Synergy Effect of Nitrogen and Molybdenum on Activated Carbon Matrix for Selective Adsorptive Desulfurization: Insights into Surface Chemistry Modification

2021 ◽  
Author(s):  
Musa O Azeez ◽  
Abdulkadir Tanimu ◽  
Khalid Alhooshani ◽  
Saheed A. Ganiyu
Keyword(s):  
Activated Carbon ◽  
Surface Chemistry ◽  
Adsorption Capacity ◽  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
Pore Volume ◽  
Carbon Surface ◽  
Synergy Effect ◽  
Adsorptive Desulfurization ◽  
X Ray

Abstract This study reports the synthesis of mesoporous metal-modified nitrogen doped activated carbon (AC-N-Mo) from date seeds by ZnCl2 activation and its applicability for selective adsorptive desulfurization of dibenzothiophene (DBT). The AC-N-Mo exhibits higher adsorption capacity for DBT at 100 mg-S/L with the maximum value of 99.7% corresponding to 19.94 mg-S/g at room temperature than the unmodified carbon with 17.96 mg-S/g despite its highest surface area and pore volume of 1027 m2g− 1 and 0.55 cm3g− 1 respectively. The adsorption capacity breakthrough follows the order AC-N-Mo > AC-Mo > AC > AC-N. AC-N-Mo also displayed excellent selectivity in the presence of aromatics (toluene, naphthalene and 1-methylisoquinoline). The enhancement in the DBT uptake capacities of AC-N-Mo is attributed to synergy effect of nitrogen heteroatom that aid well dispersion of molybdenum nanoparticles on carbon surface thereby improving its surface chemistry and promising textural characteristics. The kinetic studies showed that the DBT adsorption proceeds via pseudo-second order kinetics while the isotherm revealed that both Freundlich and Langmuir fit the data but Freundlich fit the data more accurately for the best performing adsorbent. The physico-chemical properties (surface area, pore volume, carbon content, particle size etc.) of as-prepared adsorbents namely; AC, AC-N, AC-N-Mo and AC-Mo were characterized by N2- physisorption, X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Spectroscopy/Energy Dispersive Spectroscopy (SEM/EDS), Raman Spectroscopy (RS), Fourier Transform Infrared Spectroscopy (FTIR) and Ammonia-Temperature-Programmed Desorption (NH3-TPD).

scholarly journals Catalytic Methanol to Hydrocarbons Transformation Particularities in Case of Micro Structured Flows Application

2022 ◽  
Vol 8 (1) ◽  
pp. 17-24
Author(s):  
R. Brovko ◽  
L. Mushinskii ◽  
V. Doluda
Keyword(s):  
Fluidized Bed ◽  
Reaction Temperature ◽  
Feed Rate ◽  
Average Diameter ◽  
Predominant Formation ◽  
Medium Size ◽  
Scale Production ◽  
Liquid Hydrocarbons ◽  
Monolithic Catalyst ◽  
Methanol Feed Rate

The methanol into hydrocarbons transformation is a complex catalytic reaction accompanied by the formation of a wide range of hydrocarbons and proceeding on the surface of acid sites of various zeolites. Zeolite H-ZSM-5 considered to be most often used catalyst for this process. H-ZSM-5 is a highly dispersed material with a crystal diameter of 1–20 microns, which complicates its direct use in reactors with a fixed catalyst bed due to the high hydraulic pressure drop of the catalytic bed. Traditionally in industry, this issue is solved by using complex reactor systems with a fluidized bed, which is justified for large-scale production. In small and medium-size plants, the use of fluidized bed systems is not economically feasible. One of the possible solutions to this problem is the use of a monolithic catalyst with a supported layer of H-ZSM-5 zeolite. This article presents a study of the catalytic activity of a zeolite-containing microstructured monolith in methanol into hydrocarbons transformation. The monolith was synthesized by pressing a zeolite-containing mass followed by drying, calcining, and secondary growth of the zeolite on the monolith surface. A sample of a monolith with an average channel diameter of 0.5, 1.0, 1.5, 2.0 mm were synthesized this way. Samples of the microstructured catalyst were tested at varying temperatures from 250 to 450 °C and at varying the specific methanol feed rate from 0.65 to 2.3 kg (MeOH)/(kg (Cat) h). For this purpose, the monolithic catalyst was placed in a reactor for testing microstructured catalysts, which consisted of a pump, a temperature controller, a catalytic reactor, a condenser, a separating funnel, and a chromatograph. Varying the conditions showed that for the preferential production of gaseous C1–C4 hydrocarbons, it is advisable to carry out the reaction under the following conditions: the average diameter of the catalyst channels is 2 mm, the reaction temperature is 350 °C, the methanol feed rate is 1.65 kg (MeOH)/(kg (Cat) h). For the predominant formation of liquid hydrocarbons of the C5–C8 fraction, it is advisable to carry out the transformation of methanol into hydrocarbons under the following conditions: the average diameter of the catalyst channels is 1 mm, the reaction temperature is 350 °C, the methanol feed rate is 0.65 kg (MeOH) / (kg (Cat) h). For the predominant formation of liquid hydrocarbons of the C9–C12 fraction, it is advisable to carry out the transformation of methanol into hydrocarbons under the following conditions: the average diameter of the catalyst channels is 0.5 mm, the reaction temperature is 350 °C, and the methanol feed rate is 0.65 kg (MeOH) / (kg (Cat) h).

scholarly journals Ultrasound-Assisted Surface Modification of MWCNT Using Organic Acids

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 72
Author(s):  
Patricia A. de León-Martínez ◽  
Aidé Sáenz-Galindo ◽  
Carlos A. Ávila-Orta ◽  
Adalí O. Castañeda-Facio ◽  
Marlene L. Andrade-Guel ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Organic Acids ◽  
Functional Groups ◽  
Photoelectron Spectroscopy ◽  
Surface Defects ◽  
Low Frequency ◽  
Carbon Surface ◽  
X Ray ◽  
Different Types ◽  
Surface Modified

In the present work, multiple-wall carbon nanotubes (MWCNTs) were surface modified in an environmentally friendly way, using low-frequency ultrasonic energy. This type of modification was carried-out using two different types of organic acids, citric acid (CA) and oxalic acid (OA). The modification of the MWCNTs was confirmed by Fourier-transform infrared spectroscopy (FTIR), where functional groups such as OH, C=O, O–C=O and COOH were detected. By means of Raman spectroscopy, an increase in carbon surface defects was found. On the other hand, using X-ray photoelectron spectroscopy (XPS), oxidation was evidenced on the surface of the modified MWCNT. In both Raman spectroscopy and XPS, the results indicate a greater modification when CA is used, possibly due to the fact that CA has a larger number of functional groups. MWCNT-CA showed good dispersion in methanol, while MWCNT-OA showed good stability in methanol and ethanol. Finally, a 20% removal of creatinine efficiency improvement was found with respect to the unmodified MWCNTs, while no improvement was found in the case of urea and uric acid.

scholarly journals Free-Carbon Surface for PtCu Nanoparticles: An In Situ Near Ambient Pressure X-ray Photoelectron Spectroscopy Study

2020 ◽  
Vol 124 (35) ◽  
pp. 19046-19056
Author(s):  
Rafael Castillo ◽  
Sara Navarro-Jaén ◽  
Francisca Romero-Sarria ◽  
Virginia Pérez-Dieste ◽  
Carlos Escudero ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Free Carbon ◽  
Carbon Surface ◽  
Spectroscopy Study ◽  
X Ray

scholarly journals Preparation of Graphite Oxide Containing Different Oxygen-Containing Functional Groups and the Study of Ammonia Gas Sensitivity

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3745 ◽  
Author(s):  
Liming Luo ◽  
Tongjiang Peng ◽  
Mingliang Yuan ◽  
Hongjuan Sun ◽  
Shichan Dai ◽  
...  
Keyword(s):  
Moisture Content ◽  
Functional Groups ◽  
Reaction Temperature ◽  
Graphite Oxide ◽  
Photoelectron Spectroscopy ◽  
Raw Material ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Gas Sensitivity ◽  
X Ray

A series of graphite oxide samples were prepared using the modified Hummers method. Flake graphite was used as the raw material and the reaction temperature of the aqueous solution was changed (0 °C, 30 °C, 50 °C, 60 °C, 70 °C, 80 °C, and 100 °C). X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectral analysis, X-ray photoelectron spectroscopy, and contact angle tests were performed to characterize the structure, chemical bonding, type, and content of oxygen-containing functional groups of the graphite oxide samples. The results showed that the type and content of each oxygen-containing functional group could be controlled by changing the reaction temperature with the addition of water. As the temperature of the system increased, the degree of oxidation of the graphite oxide samples first increased and then decreased. Too high a temperature (100 °C) of the system led to the formation of epoxy groups by the decomposition of some hydroxyl groups in the samples, causing the reduction of oxygen-containing functional groups between the graphite layers, poor hydrophilic properties, and low moisture content. When the system temperature was 50 °C, the interlayer spacing of the graphite oxide samples was at its highest, the graphite was completely oxidized (C/O = 1.85), and the oxygen-containing functional groups were mainly composed of hydroxyl groups (accounting for approximately 28.88% of the total oxygen-containing functional groups). The high content of hydroxyl and carboxyl groups had good hydrophilic ability and showed the highest moisture content. The sample at 50 °C had better sensitivity to ammonia because of its high hydroxyl group and carboxyl group content, with the sample showing an excellent profile when the ammonia concentration was 20–60 ppm.

scholarly journals CO2 Methanation of Biogas Over 20 wt% Ni-Mg-Al Catalyst: On the Effect of N2, CH4, and O2 on CO2 Conversion Rate

2020 ◽  
Author(s):  
Danbee Han ◽  
Yunji Kim ◽  
Hyunseung Byun ◽  
Wonjun Cho ◽  
Youngsoon Baek
Keyword(s):  
Reaction Temperature ◽  
Photoelectron Spectroscopy ◽  
Conversion Rate ◽  
Space Velocity ◽  
Bet Surface Area ◽  
Molar Ratio ◽  
Co2 Conversion ◽  
Co2 Methanation ◽  
X Ray ◽  
Ch4 Production

Biogas contains more than 40% CO2 that can be removed to produce high quality CH4. Recently, CH4 production from CO2 methanation has been reported in several studies. In this study, CO2 methanation of biogas was performed over a 20 wt% Ni-Mg-Al catalyst, and the effects of CO2 conversion rate and CH4 selectivity were investigated as a function of CH4, O2, H2O, and N2 compositions of the biogas. At a gas hourly space velocity (GHSV) of 30,000/h, the CO2 conversion rate was ~79.3% with a CH4 selectivity of 95%. In addition, the effects of the reaction temperature (200–450 °C), GHSV (21,000–50,000/h), and H2/CO2 molar ratio (3–5) on the CO2 conversion rate and CH4 selectivity over the 20 wt% Ni-Mg-Al catalyst were evaluated. The characteristics of the catalyst were analyzed using Brunauer-Emmett-Teller (BET) surface area analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The catalyst was stable for approximately 200 h at a GHSV of 30,000/h and a reaction temperature of 350 °C. CO2 conversion and CH4 selectivity were maintained at 75% and 93%, respectively, and the catalyst was therefore concluded to exhibit stable activity.

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