查看更多>>摘要：Solar light-driven catalysis provides a viable approach for solar-to-chemical energy conversion, but it is difficult to maximize the conversion efficiency of solar energy through individual photocatalysis or photothermocatalysis. Herein, we construct a light-induced photo- and thermal-synergistic catalysis based on an adjacent Co and Cu nanoparticles co-loading on SrTiO3 nanoparticles. Under the irradiation of concentrated solar light, the SrTiO3 support is excited by ultraviolet light to induce photocatalytic effect to generate photocarriers; meanwhile, the localized surface plasma resonance-active Cu nanoparticles mainly absorb the visible-infrared light to produce hot electrons which are either quenched to generate heat or transported to active sites; finally, the active-phase Co nanoparticles converge the electrons and heat to drive CO hydrogenation into C2-C4 hydrocarbons. This study demonstrates that a rationally-designed catalyst can effectively convert solar energy to photocarriers/hot electrons and heat, and importantly, can couple them to regulate reaction pathways towards the producdon of value-added chemicals.
查看更多>>摘要：MoOx/CeO2 catalysts prepared by impregnation with (NH4)6H8Mo7O_(28) aqueous solution were applied for catalytic oxidation of 1,2-dichloroethane. MoOx exists on CeO2 fluorite as isolated (O=)2Mo(O-Ce)2, poly MoO4 and nano-particles, of which (O=)2Mo(O-Ce)2 presents high acidity and reducibility of Mo, and decreases the basicity of CeO2, leading to the formation of reactive intermediate during 1,2-dichloroethane adsorption. The activity of MoOx/CeO2 catalysts for 1,2-dichloroethane oxidation increases with acidity and surface oxygen from CeO2 domain. The catalyst with 2.6 Mo atom nm~(-2) presents the highest apparent activity with T_(90) of 280 °C in feed containing 1000/2000 ppm 1,2-dichloroethane at 60,000 h~(-1) space velocity. For chlorinated aromatic oxidation, similar high stable activity is observed. The ability of (O=)2Mo(O-Ce)2 for water dissociation promotes Cl removal, and thus, the chlorination is inhibited completely within experiment temperature. Mo~(6+)=0 of (O=)2Mo (O-Ce)2 is highly stable in wet feed, leading to high resistance of MoOx/CeO2 catalysts to water.
查看更多>>摘要：We report the synthesis and characterization, reaction kinetics, and deactivation mechanism of a series of catalysts with metallic nickel (Ni) and molybdenum carbide (Mo2C) particles supported on zeolite Y (Ni-Mo2C/FAU) in methane steam reforming (MSR) reaction at 850 °C. Despite a low Ni loading of 2.4 wt%, MSR on Ni-Mo2C/ FAU exhibits high activity and stability, yet deactivation of Ni-FAU is significant. Further investigations elucidate that the catalyst deactivation is caused by Ni particle sintering via Ostwald ripening instead of coking, and steam induces hydroxylated Ni surface that accelerates sintering. Moreover, Mo2C boosts the activity and stability of Ni on zeolite Y by enhancing CH4 activation rather than activating H2O. The interplays among Mo2C and Ni particles dynamically balance the carbon formation and consumption rates, and inhibit Ni sintering. This study demonstrates that high MSR activity and stability can be achieved on transition metal carbide - Ni catalysts with systematically tuned compositional, structural, and interfacial factors.
查看更多>>摘要：The development of efficient and stable Ru catalysts is crucial for synthesis of decarbonized NH3. Herein, a series of γ-Al2O3-supported Cs-promoted Ru catalysts were prepared, among which a 1.5CS-RU/γ-Al2O3 catalyst with a Cs/Ru molar ratio of 1.5 and a Ru size of ～2 nm exhibited high NH3 synthesis rates (6.9-30 mmol g_(cat)~(-1) h~(-1)) at ～400 °C and 1 MPa. We unraveled that the surface acidity/basicity could be changed, and new active sites could be generated at the interfaces between the Ru particles and the CsOH-Cs~0 species by tuning the Cs/Ru molar ratio. Among the active sites, Cs° (minor), which transferred electrons to Ru, was present at the boundaries of the Ru particles and CsOH (major), which attracted the dissociative hydrogen atoms from the metallic Ru surfaces via a spillover effect and changed the surface acidity/basicity. This facilitated the adsorption/desorption of reactant species, tnus promoting NH3 synthesis.
查看更多>>摘要：An unexpected CO2-induced dissolution of ZnO into ionic liquids was discovered. This process exhibited high dissolution speed and the dissociated mixture was applied as an efficient Zn-based catalytic system for the CO2-promoted hydration of propargylic alcohols under atmospheric pressure with broad substrate scope. Moreover, this system could be recycled and reused for at least 16 times with excellent yields continuously obtained, which is an unprecedented record for this reaction. Significantly, this system could employ waste pigments as the ZnO source and work even under flue gas atmosphere. In the mechanistic investigations, the interaction between ZnO, CO2 and ionic liquids to give N-heterocyclic carbene/C02 adducts proved to be the key factor for this specific dissolution. These adducts were further identified to exhibit better reactivity than the normal CO2 by experimental data and density functional theory (DFT) calculations, which might be responsible for the excellent performance of the abovementioned catalytic system.
查看更多>>摘要：Herein, we assemble semi-metallic 1T' phase M0S2 on the surface Ti3C2 MXene (1T'-MoS2/Ti3C2 composite) by one-step hydrothermal method for nitrogen fixation. 1T'-MoS2/Ti3C2 composites present a high ammonia yield rate of 31.96 μg h~(-1) mg~(-1)_(cat.) at - 0.95 V vs. RHE and a Faradaic efficiency (FE) of 30.75% at - 0.7 V, which is much better than pure 1T'-MoS2 and pure Ti3C2 MXenes alone. Furthermore, the 1T'-MoS2/Ti3C2 composites exhibit good selectivity and stability with no significant decrease in ammonia yield rate and FE. Density functional theory (DFT) calculations reveal that 1T'-MoS2/Ti3C2 composite makes the activation and further reduction of *N2 more thermodynamically favorable than pure 1T-M0S2. ~(15)N isotopic labeling experiment confirms that nitrogen in produced ammonia originates from N2 in the electrolyte.
查看更多>>摘要：Because of its complexity, selective conversion of lignocellulosic biomass into platform chemicals presents significant challenges. Herein, we converted birch wood into high-yield lignin-derived phenolic monomers and dimers and holocellulose-derived polyols and monocarboxylic acids via a two-step cascade reaction using 0.1 wt % Pd on N-doped carbon (Pd_(0.1)/CNx) and passivated alumina-coated Ni on activated carbon (M2 @Al2O3/AC) catalysts. The catalytic fractionation of birch sawdust using Pd_(0.1)/CNX produced 11.1 wt% monomers, 5.6% dimers, and 63.4 wt% pulp-rich solid (PRS) based on feed weight. The subsequent conversion of PRS over passivated Ni2 @Al2O3/AC produced 21.6 wt% C2-C6 polyols and 7.9 wt% monocarboxylic acids. After the whole biomass conversion reaction, the Pd_(0.1)/CNx and Ni2 @Al2O3/AC catalysts were separated using their different magnetic responses and reused three times without activity loss. The structure-performance relationships of the Pd_(0.1)/CNx catalysts synthesized using different methods and effect of passivation on the performance of the Ni2 @Al2O3/AC catalyst were analyzed.
查看更多>>摘要：To achieve the efficient electrocatalytic upgrading of nitrate (NO3~-) and hydrogen sulfide (H2S) to value-added ammonia (NH3) and sulfur (S) from wastewater, herein, we report a remarkable nitrogen-doped carbon nanotubes encapsulated iron carbide array electrode (Fe3C@N-CNTs/IF) as both cathode and anode for the efficient electrocatalytic reduction of NO3~- to NH3 and oxidation of H2S to S, respectively. Both experimental and theoretical calculation confirm the high activity of Fe3C@N-CNTs/IF. A maximal NH3 faradaic efficiency of ～97.9% with the yield rate of 0.922 mg h~(-1) cm~(-2) at - 1.1 V vs. SCE and the S yield rate of 33.76 mg h~(-1) cm~(-2) at the current density of 100 mA cm~(-2) can be achieved. In addition, a flow cell is employed with a multifunctional Fe3C@N-CNTs/IF electrode with channels made by laser to maintains excellent stability for continuous upcycling NO3~- and H2S to produce NH3 and S, which demonstrates its massive potential for practical application.
查看更多>>摘要：This work addresses the stability of different Ru-based dual function materials (DFM, x% Ru, 6.1% "Na2O"/ Al2O3) during cycles of CO2 capture from simulated power plant effluent (320 °C; 7.5% CO2, 15% steam, 4.5% O2, balance N2 (v/v)) and subsequent catalytic methanation. Aging studies are carried out to simulate natural gas combustion flue gas on DFM granules, tablets, and ring tablets prepared by sequentially impregnating Ru and Na2O. Stability increases with Ru loading; however, 0.5% Ru DFMs demonstrate a small but steady loss of CH4 produced per cycle consistent with deactivation of the Ru component likely due to exposure to high levels of O2 and steam in the flue gas. CO chemisorption, in-situ FT-IR, and transient microreactor studies all verify that there is loss in Ru active surface area, possibly due to sintering, which consequently results in lower methanating ability.
查看更多>>摘要：Modulation of electronic structure and facilitation of *H adsorption through defective sites is of great significance for photocatalytic hydrogen evolution. Here, we designed an S vacancies 1T-WS2/CdS to achieve 70.9 mmol/g/h hydrogen evolution rate accompanied with 39.1% AQY at 500 nm via coordinating the interfacial electronic engineering and photothermal effect. The photothermal effect induced by S vacancies 1T-WS2 effectively lowered the apparent activation energy from 15.96 kJ/mol to 10.51 kJ/mol, meanwhile, the directional migration of electrons from CdS to S vacancies accelerated by lattice heating was the main reason for boosting photocatalytic hydrogen evolution. Both the decrease of free energy of *H due to the existence of S vacancies and the enhancement of field strength caused by effective enrichment of electrons at the interface of S vacancies 1T-WS2/ CdS. This work provided valuable insight into the use of non-precious metal co-catalysts for photo-thermal assisted photocatalytic hydrogen evolution.
NSTL