Economic benefit analysis of low-level high vacuum compaction method from the perspective of low carbon

In order to discuss the superiorities of High Vacuum Drubbing Means (HVDM) in soft foundation treatment of roads, this paper takes the soft foundation treatment project of Wucheng Road in Wuwei County of Wanjiang City Belt in China as an example. By comparing and analyzing the economic benefit differences between HVDM method and traditional powder injection pile method in soft soil foundation treatment, the following conclusions are drawn: Low-level high-vacuum compaction method soft base processing method is better than traditional powder-jet pile method in soft foundation treatment. The method can better reduce the consumption of raw materials such as cement and stone, avoid the pollution of the social environment caused by cement production, shorten the construction period by about 50 % and save the direct labor cost. Compared with the traditional powder-sprayed pile method, total cost of the project can be saved by more than 30 % and the construction quality is controllable. The construction process is green and its social and economic benefits are remarkable

Novel magnetic carbon supported molybdenum disulfide catalyst and its application in residue upgrading

A novel hybrid material consisted of carbon covered Fe3O4 nanoparticles and MoS2 nanoflower (FCM) was designed and prepared by micelle-assisted hydrothermal methods. Multiple techniques, including X-Ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) were employed to characterize it. The results show that FCM has a flower-like morphology with a 330 nm Fe3O4 core as well as 70 nm highly crystalline MoS2 shell. FCM is superparamagnetic with a saturation magnetization of 35 emu g(-1). Then hydrocracking of Canadian bitumen residue (CBR) was applied to estimate its catalytic activity. The results show that FCM exhibits superior catalytic hydrocracking activity compared to bulk MoS2 and commercial oil-dispersed Mo(CO)(6) by the same Mo loading. Further measurement by elemental analysis, XPS and XRD reveals that the MoS2 nanoflower with abundant catalytic active sites and covered carbon layer with anti-coke ability donate to the superior upgrading performance. Besides, the catalysts can be easily recovered by the external magnetic field. This work provides a novel kind magnetic nanocatalyst which is potential for slurry-phase hydrocracking applications. (C) 2020, Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communi-cations Co., Ltd

Tailoring the structure and energy level over transition-metal doped MoS2 towards enhancing 4-nitrophenol reduction reaction

Exploring high-efficiency, robust and cost-effective catalysts for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) is greatly desirable. Herein, a series of transition-metal doped MoS2 (M-MoS2, M = Mn, Fe, Co, Ni, Cu, Zn) with expanded interlayer spacing are fabricated by one-step solvothermal strategy. Notably, nickel doped molybdenum disulfide (Ni-MoS2) is found to exhibit prominent catalytic activity with an apparent rate constant (K) of 1.09 min(-1) and excellent stability over six continuous runs of recycling experiments. The results demonstrate that the expanded interlayer spacing (0.94 nm) can increase the active sites of reactant absorption, and Ni dopants can lower the energy level (d-band center) to facilitate the desorption of H. Thus, the catalytic activity of Ni-MoS2 is enhanced by synergistically structural and energy level modulation. This study offers an effective strategy to design transition metal sulfides with higher catalytic reactivity for the environment-related catalysis processes

Facile synthesis of magnetic recyclable Fe3O4@PDA@MoS2 nanocomposites for effectively hydrocracking of residue

Magnetic nanocomposites provide manifold perspectives for sustainable development. However, the cumbersome operation process and energy consumption after treatment limit its application in the practical industry. Herein, we present a simple and universal strategy to synthesize Fe3O4@PDA@shell nanoparticles via in-situ homogeneous hydrolysis reaction growth different nanomaterials on the PDA modified Fe3O4 nanospheres, which can avoid multistep repetitive washing, redispersing, and drying. As an example, we introduced the synthesis process of Fe3O4@PDA@MoS2 catalyst used for heavy oil hydrocracking in detail. The synthesis processes were significantly simplified and the dispersity and stability of the nanosized MoS2 were improved due to the copious functional groups and strong adhesion properties of polydopamine. The as-prepared Fe3O4@P-DA@MoS2 nanoparticle catalysts showed high activity and excellent stability. The viscosity of residue was decreased by 99.8% and the recovery of the catalyst reached 90% under harsh conditions (405 degrees C at 13 MPa H-2). We also demonstrate the versatility of this strategy for other shell materials, such as WS2, VS2, Pd, and Rh components, which is promising for designing multifunctional core-shell-shell materials for various applications

Control of metal-support interaction in magnetic MoS2 catalyst to enhance hydrodesulfurization performance

Studies on the metal-support interaction have been a key step for deeply understanding the catalytic behavior of hydrodesulfurization (HDS) reactions. In particular, modification of the surface hydroxyl groups on alumina can determine its surface metal species and their dispersion degrees and thus influence the reactivity of catalysts. Herein, magnetic MoS2 nanoparticles supported on thiol groups grafted alumina (Fe3O4@Al2O3-SH@MoS2) were synthesized, leading to excellent catalytic hydrodesulfurization performance in a slurry-phase reactor of 40% desulfurization efficiency and high stability of 105 h in the long-term evaluation. Density functional theory calculations and multiple catalyst characterizations demonstrated that the grafting of thiol groups not only significantly weakened the metal-support interaction by bridging the support and active phase but also inhibited the coke formation, improved the cycle performance of the catalyst. This work proves to be an effective method to adjust the metal-support interaction, leading to enhanced catalytic performance. Besides, the magnetic properties of the catalyst enable it to be separated from the reaction media quickly, which is promising to be used in slurry reactors that process heavy crude oil

Donor-Acceptor Couples of Metal and Metal Oxides with Enriched Ni3+ Active Sites for Oxygen Evolution

Exploiting precious-metal-free and high-activity oxygen evolution reaction (OER) electrocatalysts has been in great demands toward many energy storage and conversion processes, for example, carbon dioxide reduction, metal-air batteries, and water splitting. In this study, the simple solid-state method is employed for coupling Ni (electron donors) with lower-Fermi-level MoO2 or WOx (electron acceptors) into donoracceptor ensembles with well-designed interfaces as robust electrocatalysts for OER. The resulting Ni/MoO2 and Ni/WOx electrocatalysts exhibit smaller overpotentials of 287 and 333 mV at 10 mA cm(-2) as well as smaller Tafel slopes of 51 and 65 mV/ dec, respectively, with respect to the single Ni, MoO2, WOx, and even the benchmark RuO2 in 1 M KOH. Specially, on account of a higher Fermi level of Ni in comparison with MoO2 and WOx, their strong electronic interaction results in directional interfacial electron transfer and increases the hole density over Ni, dramatically enriching the population of high-valence Ni3+ active sites and decreasing the Fermi level of Ni. The existence of Ni3+ can strengthen the chemisorption of OH-, and the downshift of the Ni Fermi level can significantly expedite migration of electrons toward the surface of catalysts during OER, thus synergistically boosting the OER catalytic performance. Furthermore, the inner Ni/MoO2 and Ni/WOx heterostructures and the electrochemically induced surface layers of oxides/hydroxides collectively boost the OER kinetics. This study highlights the importance of designing highly efficient OER electrocatalysts with high-valence active species (Ni3+) and better matched energy levels induced by the work function difference through interfacial engineering

Interfacial engineering of transition-metal sulfides heterostructures with built-in electric-field effects for enhanced oxygen evolution reaction

Developing highly efficient, durable, and non-noble electrocatalysts for the sluggish anodic oxygen evolution reaction (OER) is the pivotal for meeting the practical demand in water splitting. However, the current transition-metal electrocatalysts still suffer from low activity and durability on account of poor interfacial reaction kinetics. In this work, a facile solid-state synthesis strategy is developed to construct transition-metal sulfides heterostructures (denoted as MS2/NiS2, M = Mo or W) for boosting OER electrocatalysis. As a result, MoS2/NiS2 and WS2/NiS2 show lower overpotentials of 300 mV and 320 mV to achieve the current density of 10 mA.cm(-2), and smaller Tafel slopes of 60 mV.dec(-1) and 83 mV-dec(-1) in 1 mol.L-1 KOH, respectively, in comparison with the single MoS2, WS2, NiS2, as well as even the benchmark RuO2. The experiments reveal that the designed heterostructures have strong electronic interactions and spontaneously develop a built-in electric field at the heterointerface with uneven charge distribution based on the difference of band structures, which promote interfacial charge transfer, improve absorptivity of OH , and modulate the energy level more comparable to the OER. Thus, the designed transition-metal sulfides heterostructures exhibit a remarkably high electrocatalytic activity for OER. This study provides a simple strategy to manipulate the heterostructure interface via an energy level engineering method for OER and can be extended to fabricate other heterostructures for various energy-related applications. (C) 2021 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved