查看更多>>摘要：Ni-catalysts are promising candidate for fatty acid hydrodeoxygenation (HDO), but are limited by their quite poor HDO selectivity. Herein, a mesoporous Ni-Mo/SiO2-TiO2 catalyst was prepared by precipitation and impregnation method and used for methyl laurate HDO, yielding 96.3% n-dodecane yield at full methyl laurate conversion. Non-edible bio-lipids such as jatropha oil and waste cooking oil also converted to n-C14+16+18 hy-drocarbons with yields of 94.3% and 92.4%, respectively. Besides, Ni-Mo/SiO2TiO2 shows strong chemo-selectivity towards the HDO of ester groups. Experimental results showed that Mo-addition and Ti/Si molar ratio strongly influenced HDO selectivity. Oxygen vacancies formed on partial reduced TiO2 surface securely bond Ni NPs and activate C=O/C-O bonds, improving Ni NPs dispersion and promoting R-COOCH3 R-CHO reduction. Additional, Mo-addition switches reactant adsorption configuration from eta(1)(C)-acyl to eta(2)(C,O)-aldehyde, pro-moting the formation of R-CH2OH intermediate. Moreover, abundant Bronsted acidic sites (Mo4+-OH, Mo6+-OH, hydroxy groups) facilitate the HDO of R-CH2OH to R-CH3.
查看更多>>摘要：The ordered mesoporous Zr-modified MCM-41 materials were synthesized by using four different preparation methods including impregnation method, precipitation method, ultrasound method and trituration method, respectively; active zinc species were immobilized on the modified materials with different methods for introducing zirconia species as effective catalysts for the acetylene hydration. All the synthesized materials were characterized by various techniques including BET, FTIR, XRD, TGA, TEM, XPS, NH3-TPD, H-2-TPR, and solid stated UV-vis. The correlation between structural properties of zirconia modified support and catalytic performance of the Zn catalysts was evaluated in detailed in the acetylene hydration. It is demonstrate that the Zr-modified materials showed the excellent thermostability, and zirconia species addition could enhance the interactions between active metal and support, as well as control the metal particles size with better dispersion. In addition, the substantial enhancement of acid sites and total acid quantity for the modified materials were contributed to the zirconia species addition. Besides, activity evaluation confirms that the Zn/ZM-P catalyst showed more optimistic catalytic performance above 92% C2H2 conversion and 85% selectivity to acetaldehyde in the acetylene hydration due to the stronger metal-support interactions and more acid sites. The study would provide scientific basis for the design of metal catalysts.
查看更多>>摘要：Carbon encapsulated iron catalysts hold great potential for one-step hydroxylation of benzene to phenol due to their unique core-shell nanostructures. However, their catalytic performance is moderate, since the carbon shells have impeded their activity toward H(2)O(2)activation. Herein, we demonstrate that alloying engineering of Fe cores with Co atoms is a promising strategy to address the issue about H(2)O(2)activation. The incorporation of Co into Fe cores can generate strong synergetic effects to promote H(2)O(2)activation, while still maintaining the structural benefits of carbon shells for benzene hydroxylation reaction. As a result, the phenol yield obtained on carbon encapsulated FeCo (FeCo@C) reaches to 26.4 +/- 0.7% with a selectivity of 96.2 +/- 1.2%, much higher than that of Fe@C and Co@C. With the improved intrinsic catalytic behavior toward H2O2 activation and well reserved carbon structure benefits, FeCo@C should be a promising catalyst for a broad liquid-phase reactions using H(2)O(2)as the oxidant.
查看更多>>摘要：Vapor-phase dehydration of 1,2-propanediol to form propanal was performed over H3PO4/SiO2 catalyst with Bronsted acid sites, which exhibited a high activity for the formation of propanal, and the successive modification of H3PO4/SiO2 by WO3 and Ag could further improve both the activity and the stability of catalysts. The H3PO4/SiO2 catalyst modified by both Ag and WO3 could provide a propanal selectivity of 94.6% with a complete conversion of 1,2-propanediol in an H-2 flow at 250 ? and a weight hourly space velocity of 2.70 h(-1). Bronsted acid sites were effective for the formation of propanal, and the doping of WO3 could significantly increase the amount of Bronsted acid sites, resulting in the improvement of catalytic activity. On the other hand, the doping of Ag could protect the Bronsted acid sites and inhibit coke deposition on the catalyst surface in an H2 atmosphere, leading to the improvement of catalyst stability.
查看更多>>摘要：Electrolysis of water to produce clean and renewable hydrogen fuel is a very significant way for sustainable energy development. The most advanced catalysts for hydrogen evolution are Pt-based materials. However, due to the high cost and scarcity of Pt elements, it is indispensable to improve the stability and intrinsic catalytic activity of Pt. The design and synthesis of Pt/support materials provide an effective approach for efficient catalytic hydrogen evolution reaction (HER). Herein, an excellent heterostructure induced 4.78-Pt/V8C7 @C hybrid was synthesized as electrocatalyst for efficient electrocatalytic HER. The 4.78-Pt/V8C7 @C hybrid exhibits excellent HER activity due to the synergy interaction, which can modulate the electronic structure of Pt NPs and the hydrogen adsorption of Pt NPs surface. Notably, compared with commercial Pt/C, the 4.78-Pt/V8C7 @C hybrid exhibits more remarkable HER performance in acidic and alkaline media. The 4.78-Pt/V8C7 @C hybrid delivers an overpotential of 6 mV at 10 mA cm(-2) in 0.5 M H2SO4. And the mass activity of 0.78 mA Ptg-1 is reached at -0.02 V, which is 12.4 times that of Pt/C. This work provide that the vanadium carbide networks is an effective substrate material for the deposition of Pt NPs to improve HER activity and stability.
查看更多>>摘要：Sulfadiazine (SDZ) pollution can cause genetic mutation of organisms and lead to different kinds of disease for humans, but it is facing the dilemma of low photodegradation efficiency. Different from the traditional photo-catalysts, this work focuses on constructing a multi-electron-channel system in trimetallic metal-organic frameworks (MOFs) to accelerate the separation of electron-hole pairs, in which the carriers can be direction-ally converted among separate electron channels via Fo & BULL;rster resonance energy transfer process. As a result, the optimal trimetallic MOF can sharply remove similar to 70% of SDZ within 20 min and remain unchanged after 9 cycles. These findings provide a new inspiration for designing photogenerated carrier reaction kinetics to accelerate SDZ degradation.
查看更多>>摘要：1,3-Pentadiene plays an extremely important role in the production of polymers and fine chemicals. Herein, the LaPO(4 & nbsp;)catalyst exhibits excellent catalytic performance for the dehydration production of 1,3-pentadiene with 2,3-pentanediol, a C5 diol platform compound that can be easily obtained by hydrogenation of bio-based 2,3-pentanedione. The relationships of catalyst structure-acid/base properties-catalytic performance was estab-lished, and an acid-base synergy effect was disclosed for the on-purpose synthesis of 1,3-pentadiene. Thus, a balance between acid and base sites was required, and an optimized LaPO4 with acid/base ratio of 2.63 afforded a yield of 1,3-pentadiene as high as 61.5% at atmospheric pressure. Notably, the Bronsted acid sites with weak or medium in LaPO4 catalyst can inhibit the occurrence of pinacol rearrangement, resulting in higher 1,3-pentadiene production. In addition, the investigation on reaction pathways demonstrated that the E2 mechanism was dominant in this dehydration reaction, accompanied by the assistance of E1 and E1cb.
查看更多>>摘要：Herein, the phase and photocatalytic property of graphitic carbon nitride (g-C3N4) are modulated with the functionalization of ionic liquid (IL) by post-treatment of g-C(3)N(4 )with imidazolium sulfonic acid chloride. The structure, morphology and optoelectronic properties of synthesized catalyst were thoroughly investigated. The functionalization of Ionic liquid has induced polycrystallinity to the amorphous g-C3N4. The g-C3N4 -IL is highly efficient towards photocatalytic side-chain oxidation of toluene using H2O2 with toluene conversion of 58% with 97% benzaldehyde selectivity in acetonitrile and toluene conversion of 49% and 96% benzaldehyde selectivity in organic solvent-free conditions. The synergy between g-C3N4 and the IL elevates the visible light absorption and lower photoluminescence intensity. The g-C3N4-IL catalyst efficiently halts over-oxidation to get high selectivity for the desired product. In addition, graphene oxide and reduced graphene oxide were also functionalized with IL to examine their photocatalytic efficiency and considerable efficiencies were observed. The g-C3N4-IL is highly stable and recyclable.
查看更多>>摘要：Hydrodeoxygenation (HDO) of lignin to value-added biofuels and chemicals has a great significance for the advanced utilization of renewable lignocelluloses and the future biobased economy but is always a big challenge. Herein, a Ga-doped HZSM-5 supported metal Ru catalyst (bifunctional Ru/Ga-HZSM-5) exhibited the excellent HDO performance for converting diphenyl ether (DPE) to produce the only product, i.e., cyclohexane, under extremely mild conditions (180 ?, 1 MPa H-2 and 2 h). The oxygen-containing group in DPE was mainly removed through the cleavage of the C-O ether bond, followed by metal-and acid-catalyzed comprehensive hydrogenation and deoxygenation. Further characterization results confirmed that the doping of Ga remarkably enhanced the interaction between the metal Ru and the support. For the depolymerization of real lignin, Ru/Ga-HZSM-5 could not only significantly improve the total liquid yield of lignin, but also convert the oxygen-containing species into the aliphatic hydrocarbons.
查看更多>>摘要：gamma-Cu-2(OH)(3)Cl is used as a Fenton catalyst to mineralize phenol in high chloride solutions. The mineralization of phenol can be enhanced even at 15000 mg.L-1 NaCl under ambient pH. In addition, other aromatic contaminants including bisphenol A, benzoic acid, 2-chlorophenol, salicylic acid and aniline can also be effectively mineralized under the high chloride concentration. However, reference catalysts including CuSO4, CuO and Cu2O are significantly depressed by chloride. The chloride resistance ability of gamma-Cu-2(OH)(3)Cl is proposed. First, sigma-Cu-ligand complexes formed between Cu2+ and phenolic hydroxyl can react with H2O2 to promote the rapid reduction of Cu2+ to Cu+, which are not hindered by chloride. Second, the self-redox property of gamma-Cu-2(OH)(3)Cl which initiates the electron transfer from H2O2 to Cu2+ to generate Cu+ is improved by chloride. Third, the circumneutral pH could suppress HO center dot & nbsp; scavenging by chloride. The activation energies of phenol mineralization over gamma-Cu-2(OH)(3)Cl in chloride-free and high chloride solutions are 42.9 and 32.3 kJ.mol(-1), respectively. Chloride does not change the phenol mineralization pathway but accelerates its degradation into small carboxylic acids.
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Elsevier