Molecular Dynamic Simulation of Hydrogen Production by Catalytic Gasification of Key Intermediates of Biomass in Supercritical Water

2017 ◽  
Vol 140 (4) ◽  
Author(s):  
Hui Jin ◽  
Bin Chen ◽  
Xiao Zhao ◽  
Changqing Cao
Keyword(s):  
Supercritical Water ◽  
Active Sites ◽  
Density Functional ◽  
Free Carbon ◽  
Ni Catalyst ◽  
Catalytic Gasification ◽  
Syngas Production ◽  
Reactor Optimization ◽  
Cu Catalyst ◽  
Microscopic Reaction

Supercritical water gasification (SCWG) is an efficient and clean conversion of biomass due to the unique chemical and physical properties. Anthracene and furfural are the key intermediates in SCWG, and their microscopic reaction mechanism in supercritical water may provide information for reactor optimization and selection of optimal operating condition. Density functional theory (DFT) and reactive empirical force fields (ReaxFF) were combined to investigate the molecular dynamics of catalytic gasification of anthracene and furfural. The simulation results showed that Cu and Ni obviously increased the production of H radicals, therefore the substance SCWG process. Ni catalyst decreased the production of H2 with the residence time of 500 ps while significantly increased CO production and finally increased the syngas production. Ni catalyst was proved to decrease the free carbon production to prohibit the carbon deposition on the surface of active sites; meanwhile, Cu catalyst increased the production of free carbon.

Activated char supported Fe-Ni catalyst for syngas production from catalytic gasification of pine wood

2021 ◽  
pp. 125600
Author(s):  
Jianjun Hu ◽  
Zhentao Jia ◽  
Shuheng Zhao ◽  
Wei Wang ◽  
Quanguo Zhang ◽  
...  
Keyword(s):  
Ni Catalyst ◽  
Catalytic Gasification ◽  
Pine Wood ◽  
Syngas Production

scholarly journals Insight into the Ex Situ Catalytic Pyrolysis of Biomass over Char Supported Metals Catalyst: Syngas Production and Tar Decomposition

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1397 ◽  
Author(s):  
Mian Hu ◽  
Baihui Cui ◽  
Bo Xiao ◽  
Shiyi Luo ◽  
Dabin Guo
Keyword(s):  
Active Sites ◽  
Catalytic Pyrolysis ◽  
Supported Catalyst ◽  
Ex Situ ◽  
Molar Ratio ◽  
Ni Catalyst ◽  
Nitrogenous Compounds ◽  
Syngas Production ◽  
Valence States ◽  
Pyrolysis Of Biomass

Ex situ catalytic pyrolysis of biomass using char-supported nanoparticles metals (Fe and Ni) catalyst for syngas production and tar decomposition was investigated. The characterizations of fresh Fe-Ni/char catalysts were determined by TGA, SEM–EDS, Brunauer–Emmett–Teller (BET), and XPS. The results indicated that nanoparticles metal substances (Fe and Ni) successfully impregnated into the char support and increased the thermal stability of Fe-Ni/char. Fe-Ni/char catalyst exhibited relatively superior catalytic performance, where the syngas yield and the molar ratio of H2/CO were 0.91 Nm3/kg biomass and 1.64, respectively. Moreover, the lowest tar yield (43.21 g/kg biomass) and the highest tar catalytic conversion efficiency (84.97 wt.%) were also obtained under the condition of Ni/char. Ultimate analysis and GC–MS were employed to analyze the characterization of tar, and the results indicated that the percentage of aromatic hydrocarbons appreciably increased with the significantly decrease in oxygenated compounds and nitrogenous compounds, especially in Fe-Ni/char catalyst, when compared with no catalyst pyrolysis. After catalytic pyrolysis, XPS was employed to investigate the surface valence states of the characteristic elements in the catalysts. The results indicated that the metallic oxides (MexOy) were reduced to metallic Me0 as active sites for tar catalytic pyrolysis. The main reactions pathway involved during ex situ catalytic pyrolysis of biomass based on char-supported catalyst was proposed. These findings indicate that char has the potential to be used as an efficient and low-cost catalyst toward biomass pyrolysis for syngas production and tar decomposition.

Field Effect Modulation of Electrocatalytic Hydrogen Evolution at Back-Gated Two-Dimensional MoS2 Electrodes

2019 ◽  
Author(s):  
Yan Wang ◽  
Sagar Udyavara ◽  
Matthew Neurock ◽  
C. Daniel Frisbie
Keyword(s):  
Electric Field ◽  
Hydrogen Evolution ◽  
Active Sites ◽  
Density Functional ◽  
Electrode Materials ◽  
Density Functional Theory Calculations ◽  
Electronic Charge ◽  
Back Side ◽  
Gate Electrode ◽  
Conventional Manner

<div> <div> <div> <p> </p><div> <div> <div> <p>Electrocatalytic activity for hydrogen evolution at monolayer MoS2 electrodes can be enhanced by the application of an electric field normal to the electrode plane. The electric field is produced by a gate electrode lying underneath the MoS2 and separated from it by a dielectric. Application of a voltage to the back-side gate electrode while sweeping the MoS2 electrochemical potential in a conventional manner in 0.5 M H2SO4 results in up to a 140-mV reduction in overpotential for hydrogen evolution at current densities of 50 mA/cm2. Tafel analysis indicates that the exchange current density is correspondingly improved by a factor of 4 to 0.1 mA/cm2 as gate voltage is increased. Density functional theory calculations support a mechanism in which the higher hydrogen evolution activity is caused by gate-induced electronic charge on Mo metal centers adjacent the S vacancies (the active sites), leading to enhanced Mo-H bond strengths. Overall, our findings indicate that the back-gated working electrode architecture is a convenient and versatile platform for investigating the connection between tunable electronic charge at active sites and overpotential for electrocatalytic processes on ultrathin electrode materials.</p></div></div></div><br><p></p></div></div></div>

Towards a Design of Active Oxygen Evolution Catalysts: Insights from Automated Density Functional Theory Calculations and Machine Learning

2019 ◽  
Author(s):  
Seoin Back ◽  
Kevin Tran ◽  
Zachary Ulissi
Keyword(s):  
Machine Learning ◽  
Oxygen Evolution ◽  
Active Sites ◽  
Density Functional ◽  
Chemical Space ◽  
Density Functional Theory Calculations ◽  
Catalyst Design ◽  
Transition Metal Catalysts ◽  
Oxide Materials ◽  
Design Strategies

<div> <div> <div> <div><p>Developing active and stable oxygen evolution catalysts is a key to enabling various future energy technologies and the state-of-the-art catalyst is Ir-containing oxide materials. Understanding oxygen chemistry on oxide materials is significantly more complicated than studying transition metal catalysts for two reasons: the most stable surface coverage under reaction conditions is extremely important but difficult to understand without many detailed calculations, and there are many possible active sites and configurations on O* or OH* covered surfaces. We have developed an automated and high-throughput approach to solve this problem and predict OER overpotentials for arbitrary oxide surfaces. We demonstrate this for a number of previously-unstudied IrO2 and IrO3 polymorphs and their facets. We discovered that low index surfaces of IrO2 other than rutile (110) are more active than the most stable rutile (110), and we identified promising active sites of IrO2 and IrO3 that outperform rutile (110) by 0.2 V in theoretical overpotential. Based on findings from DFT calculations, we pro- vide catalyst design strategies to improve catalytic activity of Ir based catalysts and demonstrate a machine learning model capable of predicting surface coverages and site activity. This work highlights the importance of investigating unexplored chemical space to design promising catalysts.<br></p></div></div></div></div><div><div><div> </div> </div> </div>

scholarly journals Study on the adsorption selection of CH$$_4$$ on CuO (110) versus (111) surfaces: a density functional theory study

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Long Lin ◽  
Linwei Yao ◽  
Shaofei Li ◽  
Zhengguang Shi ◽  
Kun Xie ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Adsorption Capacity ◽  
Active Sites ◽  
Density Functional ◽  
Oxygen Vacancies ◽  
Density Functional Theory Calculations ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Strong Adsorption ◽  
Selection Of

AbstractFinding the active sites of suitable metal oxides is a key prerequisite for detecting CH$$_4$$ 4 . The purpose of the paper is to investigate the adsorption of CH$$_4$$ 4 on intrinsic and oxygen-vacancies CuO (111) and (110) surfaces using density functional theory calculations. The results show that CH$$_4$$ 4 has a strong adsorption energy of −0.370 to 0.391 eV at all site on the CuO (110) surface. The adsorption capacity of CH$$_4$$ 4 on CuO (111) surface is weak, ranging from −0.156 to −0.325 eV. In the surface containing oxygen vacancies, the adsorption capacity of CuO surface to CH$$_4$$ 4 is significantly stronger than that of intrinsic CuO surface. The results indicate that CuO (110) has strong adsorption and charge transfer capacity for CH$$_4$$ 4 , which may provide experimental guidance.

scholarly journals Density Functional Theory and Molecular Docking Investigations of the Chemical and Antibacterial Activities for 1-(4-Hydroxyphenyl)-3-phenylprop-2-en-1-one

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3631
Author(s):  
Ahmed M. Deghady ◽  
Rageh K. Hussein ◽  
Abdulrahman G. Alhamzani ◽  
Abeer Mera
Keyword(s):  
Density Functional Theory ◽  
Antibacterial Activity ◽  
Molecular Docking ◽  
Carbonyl Group ◽  
Active Sites ◽  
Density Functional ◽  
Chemical Reactivity ◽  
Basis Set ◽  
Molecular Docking Study ◽  
Functional Theory

The present investigation informs a descriptive study of 1-(4-Hydroxyphenyl) -3-phenylprop-2-en-1-one compound, by using density functional theory at B3LYP method with 6-311G** basis set. The oxygen atoms and π-system revealed a high chemical reactivity for the title compound as electron donor spots and active sites for an electrophilic attack. Quantum chemical parameters such as hardness (η), softness (S), electronegativity (χ), and electrophilicity (ω) were yielded as descriptors for the molecule’s chemical behavior. The optimized molecular structure was obtained, and the experimental data were matched with geometrical analysis values describing the molecule’s stable structure. The computed FT-IR and Raman vibrational frequencies were in good agreement with those observed experimentally. In a molecular docking study, the inhibitory potential of the studied molecule was evaluated against the penicillin-binding proteins of Staphylococcus aureus bacteria. The carbonyl group in the molecule was shown to play a significant role in antibacterial activity, four bonds were formed by the carbonyl group with the key protein of the bacteria (three favorable hydrogen bonds plus one van der Waals bond) out of six interactions. The strong antibacterial activity was also indicated by the calculated high binding energy (−7.40 kcal/mol).

scholarly journals Engineering single-atomic ruthenium catalytic sites on defective nickel-iron layered double hydroxide for overall water splitting

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Panlong Zhai ◽  
Mingyue Xia ◽  
Yunzhen Wu ◽  
Guanghui Zhang ◽  
Junfeng Gao ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Water Splitting ◽  
Layered Double Hydroxide ◽  
Hydrogen Evolution Reaction ◽  
Active Sites ◽  
Density Functional ◽  
Rational Design ◽  
Single Atom ◽  
Nickel Iron ◽  
Double Hydroxide

AbstractRational design of single atom catalyst is critical for efficient sustainable energy conversion. However, the atomic-level control of active sites is essential for electrocatalytic materials in alkaline electrolyte. Moreover, well-defined surface structures lead to in-depth understanding of catalytic mechanisms. Herein, we report a single-atomic-site ruthenium stabilized on defective nickel-iron layered double hydroxide nanosheets (Ru1/D-NiFe LDH). Under precise regulation of local coordination environments of catalytically active sites and the existence of the defects, Ru1/D-NiFe LDH delivers an ultralow overpotential of 18 mV at 10 mA cm−2 for hydrogen evolution reaction, surpassing the commercial Pt/C catalyst. Density functional theory calculations reveal that Ru1/D-NiFe LDH optimizes the adsorption energies of intermediates for hydrogen evolution reaction and promotes the O–O coupling at a Ru–O active site for oxygen evolution reaction. The Ru1/D-NiFe LDH as an ideal model reveals superior water splitting performance with potential for the development of promising water-alkali electrocatalysts.

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