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Yurong He

Bio: Yurong He is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Catalysis & Dissociation (chemistry). The author has an hindex of 10, co-authored 28 publications receiving 298 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the influence of different iron carbides on the activity and selectivity of iron-based Fischer-Tropsch catalysts has been studied, and the intrinsic FTS activity is assigned to each corresponding iron carbide based on the phase composition and the particle size.
Abstract: The influence of different iron carbides on the activity and selectivity of iron-based Fischer–Tropsch catalysts has been studied. Different iron carbide phases are obtained by the pretreatment of a binary Fe/SiO2 model catalyst (prepared by coprecipitation method) to different gas atmospheres (syngas, CO, or H2). The phase structures, compositions, and particle sizes of the catalysts are characterized systematically by XRD, XAFS, MES, and TEM. It is found that in the syngas-treated catalyst only χ-Fe5C2 carbide is formed. In the CO-treated catalyst, Fe7C3 and χ-Fe5C2 with a bimodal particle size distribution are formed, while the H2-treated catalyst exhibits the bimodal size distributed e-Fe2C and χ-Fe5C2 after a Fischer–Tropsch synthesis (FTS) reaction. The intrinsic FTS activity is calculated and assigned to each corresponding iron carbide based on the phase composition and the particle size. It is identified that Fe7C3 has the highest intrinsic activity (TOF = 4.59 × 10–2 s–1) among the three candidat...

181 citations

Journal ArticleDOI
TL;DR: The adsorption and co-adsorption of CO and H2 at different coverages on p(4 × 4) Ru(0001) have been computed using periodic density functional theory (GGA-RPBE) and atomistic thermodynamics and provide the basis for exploring the mechanisms of catalytic conversion of synthesis gas.
Abstract: The adsorption and co-adsorption of CO and H2 at different coverages on p(4 × 4) Ru(0001) have been computed using periodic density functional theory (GGA-RPBE) and atomistic thermodynamics. Only molecular CO adsorption is possible and the saturation coverage is 0.75 ML (nCO = 12) with CO molecules co-adsorbed at different sites and has a hexagonal adsorption pattern as found by low energy electron diffraction. Only dissociative H2 adsorption is possible and the saturation coverage is 1 ML (nH = 16) with H atoms at face-centered cubic sites. The computed CO and H2 desorption patterns and temperatures agree reasonably with the experiments under ultrahigh vacuum conditions. For CO and H2 co-adsorption (nCO + mH2; n = 1–6 and m = 7, 6, 5, 5, 3, 1), CO pre-coverage affects H adsorption strongly, and each pre-adsorbed CO molecule blocks 2H adsorption sites and H2 does not adsorb on the surface with CO pre-coverage larger than 0.44 ML (nCO = 7); all these are in full agreement with the experiments under ultrahigh vacuum conditions. Our results provide the basis for exploring the mechanisms of catalytic conversion of synthesis gas.

49 citations

Journal ArticleDOI
TL;DR: For the hydroformylation of alkenes, developing ligand-free heterogeneous catalysts is a research focus because of both fundamental research interests and potential commercial applications as discussed by the authors.
Abstract: For the hydroformylation of alkenes, developing ligand-free heterogeneous catalysts is a research focus because of both fundamental research interests and potential commercial applications. However...

33 citations

Journal ArticleDOI
TL;DR: In this article, a series of tetragonal ZrO2 with crystal sizes ranging between 4.0 and 11.3 nm was successfully prepared using UiO-66 as precursors.

33 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigate carbon diffusion induced by tensile, screw dislocation, edge dislocation and polycrystal boundary through reactive molecular dynamics simulations with ReaxFF potentials.
Abstract: Carbon diffusion is a critical process to the manufacture of many industry products, such as iron carbides, stainless steels, and carbon materials. Here we investigate carbon diffusion induced by tensile, screw dislocation, edge dislocation, and polycrystal boundary through reactive molecular dynamics simulations with ReaxFF potentials. The temperature enhances the dynamics and therefore the carbon diffusion. The pre-existing defects promote the carbon diffusion with a linear relationship between carbon diffusion barrier and strain as well as line defect concentrations. Furthermore, we also observed a linear relationship between the carbon diffusion barrier and the volume fractions of the polycrystalline boundary, indicating that the grain boundary mechanism is prominent in carbon diffusion in the carbon iron.

26 citations


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01 May 1993
TL;DR: Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems.
Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

29,323 citations

Journal ArticleDOI
TL;DR: In this paper, the challenges and opportunities in converting CO2 directly to olefins over a single tandem catalyst are discussed, and three routes: direct hydrogenation, methanol synthesis, and Fischer-Tropsch synthesis.
Abstract: The utilization of CO2 as a carbon source for synthesis of value-added chemicals and fuels, particularly light olefins, is one of the most attractive routes to convert CO2 as part of a large-scale process. Designing active, selective, and stable catalysts for olefin production is challenging because of the difficulty characterizing structure–property relationships for the highly complex CO2 hydrogenation reaction network. To understand the challenges and opportunities in converting CO2 directly to olefins over a single tandem catalyst, this Perspective reviews the following three routes: (1) direct hydrogenation of CO2 to olefins over promoted catalysts; (2) methanol synthesis followed by methanol-to-olefins (MeOH-mediated route); (3) CO production via the reverse-water–gas-shift reaction, followed by Fischer–Tropsch synthesis (CO-mediated route). Future research directions are proposed on the critical research areas of elucidating reaction mechanisms by combining in situ characterization techniques with ...

169 citations

Journal ArticleDOI
TL;DR: The key zeolite descriptors that influence catalytic performance, such as framework topologies, nanoconfinement effects, Brønsted acidities, secondary-pore systems, particle sizes, extraframework cations and atoms, hydrophobicity and hydrophilicity, and proximity between acid and metallic sites are discussed to provide a deep understanding of the significance of zeolites to C1 chemistry.
Abstract: C1 chemistry, which is the catalytic transformation of C1 molecules including CO, CO2 , CH4 , CH3 OH, and HCOOH, plays an important role in providing energy and chemical supplies while meeting environmental requirements. Zeolites are highly efficient solid catalysts used in the chemical industry. The design and development of zeolite-based mono-, bi-, and multifunctional catalysts has led to a booming application of zeolite-based catalysts to C1 chemistry. Combining the advantages of zeolites and metallic catalytic species has promoted the catalytic production of various hydrocarbons (e.g., methane, light olefins, aromatics, and liquid fuels) and oxygenates (e.g., methanol, dimethyl ether, formic acid, and higher alcohols) from C1 molecules. The key zeolite descriptors that influence catalytic performance, such as framework topologies, nanoconfinement effects, Bronsted acidities, secondary-pore systems, particle sizes, extraframework cations and atoms, hydrophobicity and hydrophilicity, and proximity between acid and metallic sites are discussed to provide a deep understanding of the significance of zeolites to C1 chemistry. An outlook regarding challenges and opportunities for the conversion of C1 resources using zeolite-based catalysts to meet emerging energy and environmental demands is also presented.

150 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed to use CO2 as feedstock to produce fine chemicals and renewable fuels, which presents unique challenges in its implementation at scale, such as heterogeneous catalysis.
Abstract: Utilization of CO2 as feedstock to produce fine chemicals and renewable fuels is a highly promising field, which presents unique challenges in its implementation at scale. Heterogeneous catalysis w...

140 citations

Journal ArticleDOI
TL;DR: In this paper, a highly active, selective, and stable catalyst for the hydrogenation of CO2 to short chain olefins was synthesized in one single step by using a metal organic framework as catalyst precursor.
Abstract: We report the synthesis of a highly active, selective, and stable catalyst for the hydrogenation of CO2 to short chain olefins in one single step by using a metal organic framework as catalyst precursor. By studying the promotion of the resulting Fe(41 wt %)-carbon composites with different elements (Cu, Mo, Li, Na, K, Mg, Ca, Zn, Ni, Co, Mn, Fe, Pt, and Rh), we have found that only K is able to enhance olefin selectivity. Further catalyst optimization in terms of promoter loading results in catalysts displaying unprecedented C2–C4 olefin space time yields of 33.6 mmol·gcat–1·h–1 at XCO2 = 40%, 320 °C, 30 bar, H2/CO2 = 3, and 24 000 mL·g–1·h–1. Extensive characterization demonstrates that K promotion affects catalytic performance by (i) promoting a good balance between the different Fe active phases playing a role in CO2 hydrogenation, namely, iron oxide and iron carbides and by (ii) increasing CO2 and CO uptake while decreasing H2 affinity, interactions responsible for boosting olefin selectivity.

139 citations