scholarly journals Non-Solvent Synthesis of a Robust Potassium-Doped PdCu-Pd-Cu@C Nanocatalyst for High Selectively Tandem Reactions

Catalysts ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1191
Author(s):  
Sanha Jang ◽  
Dicky Annas ◽  
Sehwan Song ◽  
Jong-Seong Bae ◽  
Sungkyun Park ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Alkali Metal ◽  
Gas Flow ◽  
High Surface ◽  
High Surface Area ◽  
Weight Ratio ◽  
Pd Nanoparticles ◽  
Catalytic Performance ◽  
Mechanical Grinding ◽  
Metal Doped

A non-solvent synthesis of alkali metal-doped PdCu-Pd-Cu@C is presented that needs no mechanical grinding and utilizes heat treatment under an N2 gas flow. Pluronic® F127 is used to generate pores and a high surface area, and tannic acid is used as a carbon source for the PdCu-Pd-Cu@C nanocatalysts. Because some C is transferred to organic compounds during the nitrogen heat treatment, this demonstrated the advantage of raising the weight ratio of active metals comparatively. The PdCu-Pd-Cu@C nanocatalyst developed in this study outperformed commercial Pd/C catalysts by bimetallic PdCu-Pd-Cu nanoparticles and Pd nanoparticles in terms of catalytic activity (selectivity of commercial Pd/C: 45%; PdCu-Pd-Cu@C nanocatalyst: 76%). The alkali metal dopants increase the selectivity of the final product on the PdCu-Pd-Cu@C surface because they are electron-rich, which assists in the adsorption of the substrate (selectivity of PdCu-Pd-Cu@C nanocatalyst: 76%; K-doped PdCu-Pd-Cu@C nanocatalysts: 90%). Furthermore, even after being reused 5 times in this research, the final catalytic performance was comparable to that of the initial catalyst.

scholarly journals Pd Nanoparticles Stabilized on the Cross-Linked Melamine-Based SBA-15 as a Catalyst for the Mizoroki–Heck Reaction

2021 ◽  
Author(s):  
Ayat Nuri ◽  
Abolfazl Bezaatpour ◽  
Mandana Amiri ◽  
Nemanja Vucetic ◽  
Jyri-Pekka Mikkola ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Inductively Coupled Plasma ◽  
High Surface ◽  
High Surface Area ◽  
Coupling Reaction ◽  
Pd Nanoparticles ◽  
Significant Activity ◽  
Inductively Coupled ◽  
Transmission Electron ◽  
Ft Ir

AbstractMesoporous SBA-15 silicate with a high surface area was prepared by a hydrothermal method, successively modified by organic melamine ligands and then used for deposition of Pd nanoparticles onto it. The synthesized materials were characterized with infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), nitrogen physisorption, scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), nuclear magnetic resonance (NMR) and inductively coupled plasma (ICP-OES). The catalyst was effectively used in the Mizoroki–Heck coupling reaction of various reactants in the presence of an organic base giving the desired products in a short reaction time and with small catalysts loadings. The reaction parameters such as the base type, amounts of catalyst, solvents, and the temperature were optimized. The catalyst was easily recovered and reused at least seven times without significant activity losses. Graphic Abstract

scholarly journals Developing Eco-Friendly and Cost-Effective Porous Adsorbent for Carbon Dioxide Capture

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1962
Author(s):  
Mahboubeh Nabavinia ◽  
Baishali Kanjilal ◽  
Noahiro Fujinuma ◽  
Amos Mugweru ◽  
Iman Noshadi
Keyword(s):  
Carbon Dioxide ◽  
Surface Area ◽  
Co2 Capture ◽  
High Surface ◽  
Scale Up ◽  
Polymer Networks ◽  
High Surface Area ◽  
Excellent Thermal Stability ◽  
Doped Polymers ◽  
Metal Doped

To address the issue of global warming and climate change issues, recent research efforts have highlighted opportunities for capturing and electrochemically converting carbon dioxide (CO2). Despite metal doped polymers receiving widespread attention in this respect, the structures hitherto reported lack in ease of synthesis with scale up feasibility. In this study, a series of mesoporous metal-doped polymers (MRFs) with tunable metal functionality and hierarchical porosity were successfully synthesized using a one-step copolymerization of resorcinol and formaldehyde with Polyethyleneimine (PEI) under solvothermal conditions. The effect of PEI and metal doping concentrations were observed on physical properties and adsorption results. The results confirmed the role of PEI on the mesoporosity of the polymer networks and high surface area in addition to enhanced CO2 capture capacity. The resulting Cobalt doped material shows excellent thermal stability and promising CO2 capture performance, with equilibrium adsorption of 2.3 mmol CO2/g at 0 °C and 1 bar for at a surface area 675.62 m2/g. This mesoporous polymer, with its ease of synthesis is a promising candidate for promising for CO2 capture and possible subsequent electrochemical conversion.

Efficient and Reusable Silica Gel Supported Metal Ionic Liquid Catalysts for Palmitic Acid Esterification to Biodiesel

2021 ◽  
Vol 43 (1) ◽  
pp. 1-1
Author(s):  
Guo Yingwei Guo Yingwei ◽  
Chen Xuedan Chen Xuedan ◽  
Yan Shiting Yan Shiting ◽  
Zhang Zhengliang Zhang Zhengliang ◽  
Chen Yuqin Chen Yuqin ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Palmitic Acid ◽  
Silica Gel ◽  
High Surface ◽  
High Surface Area ◽  
Kinetic Studies ◽  
Catalytic Performance ◽  
Reaction Conditions ◽  
Acid Esterification ◽  
Supported Metal

A series of silica gel (SG) supported metal ionic liquid catalysts (x[Bmim]Cl-CrCl3/SG) were synthesized and exploited for the esterification of palmitic acid (PA) with methanol (ML) to produce biodiesel efficiently. The 10%[Bmim]Cl-CrCl3/SG catalyst with high surface area and desirable acidity exhibited the best catalytic performance and reusability after six consecutive running cycles. Based on the response surface analysis, the optimal reaction conditions were obtained as follows: methanol/acid mole ratio = 11:1 mol/mol, catalyst amount = 5.3 wt%, reaction time = 65 min, as well as reaction temperature = 373 K, reaching to a biodiesel yield of 96.1%. Further kinetic studies demonstrated that the esterification of PA with ML obeyed 1.41 order kinetics for acid concentration with the activation energy of 16.88 kJ/mol

Surface Hardness Modify and Improve Wear Properties of EP\ NanoZrO2

2021 ◽  
Vol 19 (2) ◽  
pp. 77-82
Author(s):  
Fadhil K. Farhan ◽  
Aws Abbas Hussein ◽  
Ali Q. Tuama
Keyword(s):  
Wear Resistance ◽  
High Surface ◽  
Ceramic Powder ◽  
High Surface Area ◽  
Surface Hardness ◽  
Weight Ratio ◽  
Hardness Test ◽  
Wear Properties ◽  
Mechanical Mixing ◽  
Dioxide Powder

The liquid and mechanical mixing method was used in addition to ultrasound technology to prepare samples according to standard conditions. The percentage of cementing with ceramic powder was adopted from 1% to 4% as a weight ratio, and by using mixing drivers, nanocomposites were prepared depending on the theoretical density of the components. The velvet density was measured using Archimedes' method, and the results showed a successive improvement and increase in density with the weight ratio of addition. The results of the particulate hardness test showed a significant improvement in the results of the prepared nanostructures compared to the base sample (pure epoxy). With regard to the properties of wear resistance (wear modulus) using the screw-on-disk method, the cemented samples showed a higher wear resistance compared to the base sample. The results were interpreted based on the values of density and hardness in addition to the properties possessed by the ceramic powder of high surface area and average granular size of 32 nanometers through scanning electron microscopy. In this work, nanostructures based on (a polymer) supported with nanoscale zirconium dioxide powder were developed.

scholarly journals High surface area nitrogen-functionalized Ni nanozymes for efficient peroxidase-like catalytic activity

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0257777
Author(s):  
Anuja Tripathi ◽  
Kenneth D. Harris ◽  
Anastasia L. Elias
Keyword(s):  
Catalytic Activity ◽  
Plasma Treatment ◽  
Surface Composition ◽  
Point Of Care ◽  
High Surface ◽  
Effective Means ◽  
High Surface Area ◽  
Catalytic Performance ◽  
Optimal Time ◽  
Ammonia Plasma

Nitrogen-functionalization is an effective means of improving the catalytic performances of nanozymes. In the present work, plasma-assisted nitrogen modification of nanocolumnar Ni GLAD films was performed using an ammonia plasma, resulting in an improvement in the peroxidase-like catalytic performance of the porous, nanostructured Ni films. The plasma-treated nanozymes were characterized by TEM, SEM, XRD, and XPS, revealing a nitrogen-rich surface composition. Increased surface wettability was observed after ammonia plasma treatment, and the resulting nitrogen-functionalized Ni GLAD films presented dramatically enhanced peroxidase-like catalytic activity. The optimal time for plasma treatment was determined to be 120 s; when used to catalyze the oxidation of the colorimetric substrate TMB in the presence of H2O2, Ni films subjected to 120 s of plasma treatment yielded a much higher maximum reaction velocity (3.7⊆10−8 M/s vs. 2.3⊆10−8 M/s) and lower Michaelis-Menten coefficient (0.17 mM vs. 0.23 mM) than pristine Ni films with the same morphology. Additionally, we demonstrate the application of the nanozyme in a gravity-driven, continuous catalytic reaction device. Such a controllable plasma treatment strategy may open a new door toward surface-functionalized nanozymes with improved catalytic performance and potential applications in flow-driven point-of-care devices.

scholarly journals Synthesis, characterization of Silica Obtained from Rice Husk and Determination its Silica Content by Modified Volumetric Method

2016 ◽  
Vol 11 (2) ◽  
pp. 93 ◽  
Author(s):  
Nijhuma Kayal ◽  
Nahar Singh
Keyword(s):  
Heat Treatment ◽  
Surface Area ◽  
Rice Husk ◽  
High Surface ◽  
High Surface Area ◽  
Atomic Emission ◽  
Silica Content ◽  
Volumetric Method ◽  
Trace Impurities ◽  
Pure Silica

<p>The objective of the work was to develop pure silica with high surface area from rice husk by chemical and heat treatment. The silica samples were characterized in terms of chemical composition, particle size distribution, morphology and surface area. The amount of silica was determined by a modified volumetric method. The trace impurities in silica were quantitatively determined by inductive coupled plasma atomic emission spectroscopy (ICP-AES). A 99% silica powder with surface area 282 m<sup>2</sup>/gm could be produced by chemical and heat treatment at 1000 ºC for 2 h.</p>

scholarly journals Improved Catalytic Transfer Hydrogenation of Levulinate Esters with Alcohols over ZrO2 Catalyst

2020 ◽  
Vol 2 (1) ◽  
pp. 28
Author(s):  
Tommaso Tabanelli ◽  
Paola Blair Vásquez ◽  
Emilia Paone ◽  
Rosario Pietropaolo ◽  
Nikolaos Dimitratos ◽  
...  
Keyword(s):  
Gas Flow ◽  
Agricultural Waste ◽  
High Surface ◽  
High Surface Area ◽  
Tetragonal Zirconia ◽  
Transfer Hydrogenation ◽  
Catalytic Transfer Hydrogenation ◽  
Flow Conditions ◽  
Catalytic Transfer ◽  
Alkyl Levulinates

Levulinic acid (LA) and its esters (alkyl levulinates) are polyfunctional molecules that can be obtained from lignocellulosic biomass. Herein, the catalytic conversion of methyl and ethyl levulinates into γ-valerolactone (GVL) via catalytic transfer hydrogenation (CTH) by using methanol, ethanol, and 2-propanol as the H-donor/solvent, was investigated under both batch and gas-flow conditions. In particular, high-surface-area, tetragonal zirconia has proven to be a suitable catalyst for this reaction. Isopropanol was found to be the best H-donor under batch conditions, with ethyl levulinate providing the highest yield in GVL. However, long reaction times and high autogenic pressures are needed in order to work in the liquid-phase at high temperature with light alcohols. The reactions occurring under continuous gas-flow conditions, at atmospheric pressure and a relatively low contact time (1 s), were found to be much more efficient, also showing excellent GVL yields when EtOH was used as the reducing agent (GVL yield of around 70% under optimized conditions). The reaction has also been tested using a true bio-ethanol, derived from agricultural waste. These results represent the very first examples of the CTH of alkyl levulinates under continuous gas-flow conditions reported in the literature.

Efficient and Reusable Silica Gel Supported Metal Ionic Liquid Catalysts for Palmitic Acid Esterification to Biodiesel

2021 ◽  
Vol 43 (1) ◽  
pp. 1-1
Author(s):  
Guo Yingwei Guo Yingwei ◽  
Chen Xuedan Chen Xuedan ◽  
Yan Shiting Yan Shiting ◽  
Zhang Zhengliang Zhang Zhengliang ◽  
Chen Yuqin Chen Yuqin ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Palmitic Acid ◽  
Silica Gel ◽  
High Surface ◽  
High Surface Area ◽  
Kinetic Studies ◽  
Catalytic Performance ◽  
Reaction Conditions ◽  
Acid Esterification ◽  
Supported Metal

A series of silica gel (SG) supported metal ionic liquid catalysts (x[Bmim]Cl-CrCl3/SG) were synthesized and exploited for the esterification of palmitic acid (PA) with methanol (ML) to produce biodiesel efficiently. The 10%[Bmim]Cl-CrCl3/SG catalyst with high surface area and desirable acidity exhibited the best catalytic performance and reusability after six consecutive running cycles. Based on the response surface analysis, the optimal reaction conditions were obtained as follows: methanol/acid mole ratio = 11:1 mol/mol, catalyst amount = 5.3 wt%, reaction time = 65 min, as well as reaction temperature = 373 K, reaching to a biodiesel yield of 96.1%. Further kinetic studies demonstrated that the esterification of PA with ML obeyed 1.41 order kinetics for acid concentration with the activation energy of 16.88 kJ/mol

Oxygen uptake by porcine colon contents

1998 ◽  
Vol 1998 ◽  
pp. 163-163
Author(s):  
K. Hillman
Keyword(s):  
Dissolved Oxygen ◽  
Surface Area ◽  
Gas Flow ◽  
High Surface ◽  
High Surface Area ◽  
Oxygen Electrode ◽  
Gut Contents ◽  
Constant Flow Rate ◽  
Anaerobic Microorganisms ◽  
Ringer’S Solution

Since the gut environment is generally assumed to be anaerobic, studies of the monogastric intestinal microflora have concentrated on the anaerobic microorganisms. However, the intestinal epithelium constitutes a very high surface area in relation to the volume of the gut contents, and all of this surface area is richly supplied with blood. Appreciable dissolved oxygen concentrations can be detected in the intestines of anaesthetised piglets (Hillman et al, 1993), although this is never detectable in the intestines of killed animals. It was considered important to investigate the persistence of intestinal oxygen after death, in order to determine the accuracy of postmortem measurements of this component of the intestinal environment. This report demonstrates the rapidity of removal of oxygen by porcine colon contents, and indicates that, since the oxygen supply to the intestine stops when the blood circulation stops, accurate measurements of dissolved oxygen can never be made in the intestines of killed animals.Colon contents were obtained from three freshly slaughtered 20 kg piglets and diluted to 20% (w/v) slurries in quarter-strength Ringer's solution (Unipath, UK). The slurries were transferred (25 ml) to 50 ml conical flasks, stirred by magnetic follower (approx 400 rpm) and surrounded by a water jacket to maintain a temperature of 39°C in the vessel contents. A polarographic oxygen electrode was inserted so that the membrane was submerged. Gas flow through the headspace was provided by compressed air and nitrogen, mixed via a pair of needle valves to provide a constant flow rate of 600 ml min-1. Calibration of the system was performed in sterile Ringer's solution using air and oxygen-free nitrogen: calibration was repeated between each experiment.

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