Influence of Ag Metal Dispersion on the Catalyzed Reduction of CO2 into Chemical Fuels over Ag–ZrO2 Catalysts
Ontology highlight
ABSTRACT:
SUBMITTER:
PROVIDER: S-EPMC9520683 | biostudies-literature | 2022 Sep
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:The inherent variability and insufficiencies in the co-production of propylene from steam crackers has raised concerns regarding the global propylene production gap and has directed industry to develop more on-purpose propylene technologies. The oxidative dehydrogenation of propane by CO2 (CO2-ODHP) can potentially fill this gap while consuming a greenhouse gas. Non-precious FeNi and precious NiPt catalysts supported on CeO2 have been identified as promising catalysts for CO2-ODHP and dry reforming, respectively, in flow reactor studies conducted at 823 K. In-situ X-ray absorption spectroscopy measurements revealed the oxidation states of metals under reaction conditions and density functional theory calculations were utilized to identify the most favorable reaction pathways over the two types of catalysts.
| S-EPMC5893610 | biostudies-literature
Project description:The electrochemical carbon dioxide reduction reaction (CO2RR) to C2 chemicals has received great attention. Here, we report the cuprous oxide (Cu2O) nanocubes cooperated with silver (Ag) nanoparticles via the replacement reaction for a synergetic CO2RR. The Cu2O-Ag tandem catalyst exhibits an impressive Faradaic efficiency (FE) of 72.85% for C2 products with a partial current density of 243.32 mA·cm-2. The electrochemical experiments and density functional theory (DFT) calculations reveal that the introduction of Ag improves the intermediate CO concentration on the catalyst surface and meanwhile reduces the C-C coupling reaction barrier energy, which is favorable for the synthesis of C2 products.
| S-EPMC8070483 | biostudies-literature
Project description:The thermo-catalytic synthesis of hydrocarbons from CO2 and H2 is of great interest for the conversion of CO2 into valuable chemicals and fuels. In this work, we aim to contribute to the fundamental understanding of the effect of alloying on the reaction yield and selectivity to a specific product. For this purpose, Fe-Co alloy nanoparticles (nanoalloys) with 30, 50 and 76 wt% Co content are synthesized via the Inert Gas Condensation method. The nanoalloys show a uniform composition and a size distribution between 10 and 25 nm, determined by means of X-ray diffraction and electron microscopy. The catalytic activity for CO2 hydrogenation is investigated in a plug flow reactor coupled with a mass spectrometer, carrying out the reaction as a function of temperature (393-823 K) at ambient pressure. The Fe-Co nanoalloys prove to be more active and more selective to CO than elemental Fe and Co nanoparticles prepared by the same method. Furthermore, the Fe-Co nanoalloys catalyze the formation of C2-C5 hydrocarbon products, while Co and Fe nanoparticles yield only CH4 and CO, respectively. We explain this synergistic effect by the simultaneous variation in CO2 binding energy and decomposition barrier as the Fe/Co ratio in the nanoalloy changes. With increasing Fe content, increased activation temperatures for the formation of CH4 (from 440 K to 560 K) and C2-C5 hydrocarbons (from 460 K to 560 K) are observed.
| S-EPMC7408123 | biostudies-literature
Project description:A leading method for hydrogen production that is free of carbon oxides is catalytic methane decomposition. In this research, Fe and Fe-Ni supported catalysts prepared by the wet impregnation method were used in methane decomposition. The effects of doping the parent support (ZrO2) with La2O3 and WO3 were studied. It was discovered that the support doped with La2O3 gave the best performance in terms of CH4 conversion, H2 yield, and stability at the test condition, 800°C and 4,000-ml h-1 g-1 cat. space velocity. The addition of Ni significantly improved the performance of all the monometallic catalysts. The catalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), temperature-programmed reduction/oxidation (TPR/TPO), thermogravimetric analyzer (TGA), and microscopy (SEM and Raman) techniques. Phases of the different forms of Fe were identified by XRD. BET showed a drastic decline in the specific surface area of the catalysts with respect to the supports. TPR profiles revealed a progressive change in the valency of Fe in its combined form to the zero valence-free metal. The La2O3-promoted support gave the best performance and maintained good stability during the time on stream.
| S-EPMC7201101 | biostudies-literature
Project description:This article presents the experiments on the hydroconversion of mixtures of safflower oil (SO) mixed with straight run gas oil (SRGO) in a different ratio as an alternative to obtain biojet. The research was conducted in two stages; the first stage a mixture of SO/SRGO was subjected hydrotreating at 350 °C, 380 °C, 80 bar, LHSV 1 h−1 and 1.5 h−1, over the sulfided NiMo/Al2O3 catalyst, while in the second stage a mixture of SO/SRGO which was already hydrotreated was subjected to a hydroisomerization at 280 °C, LHSV 1 h−1, P = 30 bar, over the sulfided Pt-ZrO2/Al2O3 catalyst. It was studied the influence of SO/SRGO ratio and hydroconversion conditions on the biojet quality produced, compared with characteristics required by standard ASTM D1655. The best condition for obtaining the biojet were 380 °C, 80 bar, LHSV 1 h−1 for hydrotreating followed by hydroisomerization of 20% SO in the mixture at 280 °C, LHSV 1 h−1, P = 30 bar. Supplementary Information The online version contains supplementary material available at 10.1007/s11144-022-02197-8.
| S-EPMC8929454 | biostudies-literature
Project description:The effect of the ZrO2 loading was studied on spherical SiO2@ZrO2-CaO structures synthetized by a simple route that combines the Stöber and sol-gel methods. The texture of these materials was determined using SBET by N2 adsorption, where the increment in SiO2 spheres' surface areas was reached with the incorporation of ZrO2. Combined the characterization techniques of using different alcoholic dissolutions of zirconium (VI) butoxide 0.04 M, 0.06 M, and 0.08 M, we obtained SiO2@ZrO2 materials with 5.7, 20.2, and 25.2 wt % of Zr. Transmission electron microscopy (TEM) analysis also uncovered the shape and reproducibility of the SiO2 spheres. The presence of Zr and Ca in the core-shell was also determined by TEM. X-ray diffraction (XRD) profiles showed that the c-ZrO2 phase changed in to m-ZrO2 by incorporating calcium, which was confirmed by Raman spectroscopy. The purity of the SiO2 spheres, as well as the presence of Zr and Ca in the core-shell, was assessed by the Fourier transform infrared (FTIR) method. CO2 temperature programmed desorption (TPD-CO2) measurements confirmed the increment in the amount of the basic sites and strength of these basic sites due to calcium incorporation. The catalyst reuse in FAME production from canola oil transesterification allowed confirmation that these calcium core@shell catalysts turn out to be actives and stables for this reaction.
| S-EPMC6981678 | biostudies-literature
Project description:The bioinspired incorporation of pendant proton donors into transition metal catalysts is a promising strategy for converting environmentally deleterious CO2 to higher energy products. However, the mechanism of proton transfer in these systems is poorly understood. Herein, we present a series of cobalt complexes with varying pendant secondary and tertiary amines in the ligand framework with the aim of disentangling the roles of the first and second coordination spheres in CO2 reduction catalysis. Electrochemical and kinetic studies indicate that the rate of catalysis shows a first-order dependence on acid, CO2, and the number of pendant secondary amines, respectively. Density functional theory studies explain the experimentally observed trends and indicate that pendant secondary amines do not directly transfer protons to CO2, but instead bind acid molecules from solution. Taken together, these results suggest a mechanism in which noncooperative pendant amines facilitate a hydrogen-bonding network that enables direct proton transfer from acid to the activated CO2 substrate.
| S-EPMC5879468 | biostudies-literature
Project description:In this work, the role of In2O3 in a heterojunction with TiO2 is studied as a way of increasing the photocatalytic activity for gas-phase CO2 reduction using water as the electron donor and UV irradiation. Depending on the nature of the employed In2O3, different behaviors appear. Thus, with the high crystallite sizes of commercial In2O3, the activity is improved with respect to TiO2, with modest improvements in the selectivity to methane. On the other hand, when In2O3 obtained in the laboratory, with low crystallite size, is employed, there is a further change in selectivity toward CH4, even if the total conversion is lower than that obtained with TiO2. The selectivity improvement in the heterojunctions is attributed to an enhancement in the charge transfer and separation with the presence of In2O3, more pronounced when smaller particles are used as in the case of laboratory-made In2O3, as confirmed by time-resolved fluorescence measurements. Ternary systems formed by these heterojunctions with silver nanoparticles reflect a drastic change in selectivity toward methane, confirming the role of silver as an electron collector that favors the charge transfer to the reaction medium.
| S-EPMC8837040 | biostudies-literature
Project description:The reduction of N2 to NH3 by Mo-dependent nitrogenase at its active-site metal cluster FeMo-cofactor utilizes reductive elimination of Fe-bound hydrides with obligatory loss of H2 to activate the enzyme for binding/reduction of N2. Earlier work showed that wild-type nitrogenase and a nitrogenase with amino acid substitutions in the MoFe protein near FeMo-cofactor can catalytically reduce CO2 by two or eight electrons/protons to carbon monoxide (CO) and methane (CH4) at low rates. Here, it is demonstrated that nitrogenase preferentially reduces CO2 by two electrons/protons to formate (HCOO(-)) at rates >10 times higher than rates of CO2 reduction to CO and CH4. Quantum mechanical calculations on the doubly reduced FeMo-cofactor with a Fe-bound hydride and S-bound proton (E2(2H) state) favor a direct reaction of CO2 with the hydride ("direct hydride transfer" reaction pathway), with facile hydride transfer to CO2 yielding formate. In contrast, a significant barrier is observed for reaction of Fe-bound CO2 with the hydride ("associative" reaction pathway), which leads to CO and CH4. Remarkably, in the direct hydride transfer pathway, the Fe-H behaves as a hydridic hydrogen, whereas in the associative pathway it acts as a protic hydrogen. MoFe proteins with amino acid substitutions near FeMo-cofactor (α-70(Val→Ala), α-195(His→Gln)) are found to significantly alter the distribution of products between formate and CO/CH4.
| S-EPMC5068488 | biostudies-literature
Project description:Energy-storing artificial-photosynthetic systems for CO2 reduction must derive the reducing equivalents from a renewable source rather than from sacrificial donors. To this end, a homogeneous, integrated chromophore/two-catalyst system is described that is thermodynamically capable of photochemically driving the energy-storing reverse water-gas shift reaction (CO2 + H2 → CO + H2O), where the reducing equivalents are provided by renewable H2. The system consists of the chromophore zinc tetraphenylporphyrin (ZnTPP), H2 oxidation catalysts of the form [Cp(R)Cr(CO)3](-), and CO2 reduction catalysts of the type Re(bpy-4,4'-R2)(CO)3Cl. Using time-resolved spectroscopic methods, a comprehensive mechanistic and kinetic picture of the photoinitiated reactions of mixtures of these compounds has been developed. It has been found that absorption of a single photon by broadly absorbing ZnTPP sensitizes intercatalyst electron transfer to produce the substrate-active forms of each. The initial photochemical step is the heretofore unobserved reductive quenching of the low-energy T1 state of ZnTPP. Under the experimental conditions, the catalytically competent state decays with a second-order half-life of ∼15 μs, which is of the right magnitude for substrate trapping of sensitized catalyst intermediates.
| S-EPMC4103353 | biostudies-literature