查看更多>>摘要：The filamentous coke deposition limits the application of Ni/bio-char in the tar reforming process during biomass gasification. The addition of H2O and CO2 can improve tar conversion during the gasification process, while the effect of H2O and CO2 on filamentous coke deposition during non-oxygenates tar reforming process has not been extensively explored. To reduce the filamentous coke deposition by optimizing reforming agent, this work investigated the effect of reforming agent on filamentous coke deposition on Ni/bio-char catalyst during reforming of non-oxygenates tar. During CO2 reforming process, the accumulation of filamentous coke resulted in the decline of catalyst activity. In terms of steam reforming process, the promotion effect of steam atmosphere on mesopores of Ni/bio-char contributed to improving the conversion of non-oxygenates tar. The free radicals O* from the dissociation of H2O could oxidize the filamentous coke on Ni/bio-char, which resulted in the filamentous coke deposition (38%) in steam reforming lower than CO2 reforming (57%). Overall, the addition of steam in reforming agent contributed to improving non-oxygenates tar conversion and inhibiting filamentous coke formation during the reforming of non-oxygenates tar over Ni/bio-char.
Klimov, O. V.Nadeina, K. A.Budukva, S. V.Avdeenko, E. A....
11页
查看更多>>摘要：A NiMoP/Al(2)O(3 )catalyst deactivated at the industrial plant was subjected to oxidative regeneration and reactivation with water and an aqueous solution of citric acid. The catalyst was studied at all stages by XRD, UV-vis, Raman spectroscopy, FTIR spectroscopy, XPS and HRTEM methods. The catalyst samples after oxidative regeneration, treatment with water and rejuvenation with citric acid were tested in hydrotreatment of the model feedstock and straight-run gasoil. It was established that the regenerated catalyst contained phosphorus strongly bound to the support and soluble or insoluble Ni and Mo compounds. The catalyst after water treatment contained only insoluble Ni and Mo compounds and a phosphate monolayer, while treatment with citric acid resulted in the formation of citrate complex compounds. Ni and Mo compounds in the sulfide form, which were obtained from insoluble components, showed high activity in the target hydrotreating reactions.
查看更多>>摘要：The production of cyclohexanone, of industrial importance, is at a distance to environment friendly and efficiency. As a solution, a mild sustainable catalytic hydrogenation is presented herein, of phenol into cyclohexanone on Pd/C with potassium formate the hydrogen donor under open atmosphere. Some important reaction conditions, such as temperature, reaction time, catalyst, amount of potassium formate, etc. were investigated and analyzed. The positive growth was found to accelerate the conversion rate of phenol while reducing cyclohexanone selectivity by weakening the protection of phosphotungstic acid. Phosphotungstic acid was confirmed to be the co-catalyst exhibiting the highest activity under given conditions. Based on experiments, we have made reasonable assumptions about the reaction mechanism, while the reaction kinetics proves high reaction rates within a wide temperature range, indicating the reaction to be quick process. Furthermore, the good reusability and recyclability of Pd/C catalyst is verified to benefit future industrial applications.
查看更多>>摘要：alpha-MoC, 8-Mo2C, and MoC-Mo2C were synthesized and investigated in the selective hydrogenation of 1,3 -butadiene to understand the effect of crystal phases. The catalysts were characterized by XRD, N-2-physisorption, SEM, TEM, XPS and chemisorptions. The adsorption properties and electronic properties over MoC(001) and Mo2C(001) were investigated by DFT calculations. The catalysts were evaluated at low and high temperatures in a fixed-bed reactor. beta-Mo2C exhibits high activity and low butenes selectivity, due to the high concentration of hydrogen at each active site as well as the stronger adsorption and higher capacity of alkene; MoC-Mo2C shows better stability due to synergetic effect. At high temperature, the reaction rate is more dependent on the P-H2 than P-C4H6. Increasing P-H2 could promote the activity and reduce oligomers formation. 8-Mo2C exhibits the best performance at high temperatures concerning its high activity and the inhibition of oligomerization. This work is valuable for the non-precious metal catalyst development.
Hossein, Sayyed MahdiGhiaci, Mehran A.Kulinich, Sergei A.Wunderlich, Wilfried S....
9页
查看更多>>摘要：Carbon fiber felt (CFF) as a carbonaceous framework has received great attention in catalysis applications. In this work, a novel nanocomposite composed of cobalt oxide micro-sized particles (MPs) incorporated in nitrogen -doped carbon and wrapped by coil-like TiO2-SiO2 layer was fabricated through a co-assembly protocol including MPs implanting, hydrolysis and calcination steps. The structural properties and performance of the prepared Co/N-CFF@TiO2-SiO2 catalyst was evaluated by different techniques. Mechanical, chemical and thermal stabilities of CFF were stepwise improved and the results explain how the N-CFF matrix and strong spiral envelope promoted textural features in the final composite. Moreover, the catalyst exhibited good activity in oxidation of ethyl benzene by molecular oxygen. Under optimized conditions (130 degrees C, 12 h, 5 mL of ethyl-benzene, 20 bar O-2 pressure), the ethyl benzene conversion and acetophenone selectivity were 25% and 88%, respectively. The novel Co/N-CFF@TiO2-SiO2 catalyst showed excellent long-term stability over 6 consecutive cycles, which permits to consider it as an ideal platform for application at industrial scales due to its green and bulk nature.
查看更多>>摘要：The main purpose of photocatalytic hydrogen evolution is to fundamentally solve the problem of energy shortage and environmental pollution. In this experiment, based on the adjustment of the density of MoC quantum dots (MoC-QDs) on carbon film and the morphology of 3D porous g-C3N4, this exploring aimed at exploring the influence of various morphology combinations on the hydrogen evolution performance. Using bulk g-C3N4 (CN-B) as a reference, the tubular and honeycomb g-C3N4 were prepared by solvothermal and chemical vapor deposition methods. The experimental results show that the hydrogen production of MoCT-7 and MoCH-5 composite catalysts are 1.54 and 1.76 times that of MoCB-15, respectively, which proves that the ingenious morphology matching is an effective strategy to improve the catalytic performance. It is believed that CN-H and CN-T have unique slow photo effect and directional electron transfer characteristics, respectively. The well-dispersed MoCQDs provide abundant active sites, and the thin carbon film is conducive to the adsorption of dye molecules and electrons transfer. This experiment is expected to provide some references for the in-depth study of g-C3N4 and the design of novel photocatalysts.
查看更多>>摘要：Efficient and bifunctional catalyst for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is crucial for achieving of easily-operable water electrolysis. Herein, Ni,Fe sulfides embedded N,S co-doped carbon hybrids (NiFeS@NSCs) with tunable Ni:Fe ratios were devised through pyrolysis of methionine chelated Ni, Fe precursors. In this type of heterojunction hybrids, the spontaneous diffusion of electrons from embedded sulfides to NSC shell increases the reducibility of NSC and the oxidizability of sulfides, which are therefore capable of catalyzing OER and HER simultaneously. The typical Ni2FeS@NSC hybrid with Ni:Fe molar ratio of 2:1 offered high electrocatalytic ability for alkali OER (overpotential of 247 mV at 10 mA cm(-2)), which is significantly superior to that of individual sulfide. In addition, good HER efficiency was concurrently ensured by Ni2FeS@NSC. The symmetric water electrolyzer based on Ni2FeS@NSC required an input voltage of 1.77 V to arouse an electrolysis current density of 10 mA cm(-2). This work offers a feasible approach to enhance the OER, HER bifunctional catalytic performances via interfacial electrons diffusion within heterojunction hybrid.
查看更多>>摘要：Over the past few decades, heterogeneous photocatalysis has become a "green " alternative to traditional methods to degrade various environmental pollutants. TiO2, a low-cost and ultraviolet-light-active photocatalyst has been intensively used to decompose organic pollutants in water. The combination of TiO2 with non-toxic carbonaceous nanomaterials (CNMs) has been proved to extend TiO2 light absorption from ultraviolet (UV) to visible or even near infrared light region. Over the last decade, numerous studies on the development of CNM/TiO2 heterojunctions as efficient visible-light-responsive photocatalysts have been reported. However, a comprehensive review with respect to their synthesis, structural characteristics, photocatalytic activity enhancement is absent. In this review, the construction and characteristics (e.g. band structures, optical absorption, and interfacial charge transfer) of each class of CNM/TiO2 heterojunctions will be comprehensively reviewed. In addition, the application of CNM/TiO2 heterojunctions for photocatalytic degradation of persistent organic pollutants will be presented in detail. This review ends with a summary and future perspectives in exploring high performance CNM/TiO2 photocatalysts.
查看更多>>摘要：Considering the disadvantages of Cu-based catalyst for acetylene hydrochlorination, such as poor dispersion, severe carbon deposition and insufficient active sites, supported Cu-complex catalysts were synthesized by using phosphine-oxide organic compounds as ligands. A local active domain was successfully constructed based on the complexation of Cu atom to heteroatomic structure in meticulously selected ligands, in which the phenyl group acts as an electron donor to change the CuCl2 active site electronic structure. The density functional theory calculation proved the existence of a strong interaction between triphenylphosphine oxide and CuCl2, and synchronously, electrons on the benzene ring were transferred to the Cl atom in CuCl2, stabilizing the Cu species. This superior activity may be attributed to the heightened adsorption of HCl and weakened C2H2 and vinyl chloride adsorption by the constructed local active domain, which impedes the carbon deposition that promotes the continuous exposure of active sites. Under the reaction conditions: T = 180 ?, GHSV(C2H2) = 180 h(-1 )and V-HCl/VC2H2 = 1.2, the C2H2 conversion of 15%Cu7%TPPO/AC reaches 88%, which was over 30% higher than 15%Cu/AC catalyst. The significantly improved activity and stability of the proposed catalyst provides a reference for green and sustainable production of vinyl chloride.
NSTL
Elsevier