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? 2021 Elsevier LtdDeveloping heterogeneous catalyst containing both CO2-philic groups and catalytic active sites is highly desirable for efficient CO2 chemical fixation. In this work, a triazine-functionalized poly(ionic liquid) ...
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? 2021 Elsevier LtdDeveloping heterogeneous catalyst containing both CO2-philic groups and catalytic active sites is highly desirable for efficient CO2 chemical fixation. In this work, a triazine-functionalized poly(ionic liquid) (T-PIL) was designed and synthesized. This metal free catalyst showed extremely enhanced CO2 adsorption and improved catalytic ability for the cycloaddition reaction of CO2 without co-catalysts. Especially for the epoxides of large size and strong steric hindrance, the yields of the cyclic carbonates were improved up to three times in the presence of triazine motifs. An intramolecular synergistic mechanism of triazine and imidazolium motifs was proposed on the basis of density functional theory (DFT) calculations and diffused reflectance infrared Fourier transform spectroscopy (DRIFTS). The imidazolium groups with paired bromine anions acted as catalytic active sites and would enhance CO2 activation and the ring-opening of epoxides. While the triazine groups acting as CO2-philic groups could enhance the CO2 adsorption and activation. This work highlights that the incorporation of two motifs with synergistic effect in one catalyst can significantly improve its catalytic performance.
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In the present work, a strategy for the incorporation of nitrogen-rich units to an unsaturated Cr-based MOF, MIL100-Cr, is reported. Based on this strategy, various cyanide functional groups (diamino malononitrile, 1,3-phenylene d...
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In the present work, a strategy for the incorporation of nitrogen-rich units to an unsaturated Cr-based MOF, MIL100-Cr, is reported. Based on this strategy, various cyanide functional groups (diamino malononitrile, 1,3-phenylene diacetonitrile, and malononitrile) were incorporated into the framework and utilized as exceptional catalysts in the carbon dioxide fixation under mild, solvent, and co-catalyst free conditions. This is the first report on the application of cyano-bifunctional frameworks in cycloaddition reaction. The contemporaneous presence of accessible Lewis acid sites and pendent cyanide groups results in highly striking conversion and TON even for bulky and large substrates. High tendency and strong interaction of cyanide groups with CO2 cause a synergetic effect in the performance of the catalysts. The role of different cyanide groups applied in this work has also been studied. The reaction wouldn't proceed in the presence of pristine MOF without co-catalyst addition.
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Exploring novel and metal-free electrocatalysts for CO2 reduction is of great significance not only for reducing of CO2 emission but also for energy storage. However, searching metal-free and highly efficient electrocatalysts for ...
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Exploring novel and metal-free electrocatalysts for CO2 reduction is of great significance not only for reducing of CO2 emission but also for energy storage. However, searching metal-free and highly efficient electrocatalysts for CO2 reduction is still challenging. Here, we report that a metal-free and metallic borophene can be used as an efficient electrocatalyst for CO2 reduction. Through a comprehensive DFT investigation of CO2 activation and conversion on newly fabricated metallic 2D boron sheets (borophene, beta(12) or chi(3) boron sheets), our calculational results indicate that electron deficient borophene can provide electrons to CO2 and effectively activate the inserted CO2 by breaking pi bond of CO2. Moreover, the study demonstrates that the most feasible product of CO2 reduction on the borophene is CH4 with a limiting potential of -0.27 V and the largest activation barrier of 0.98 eV along the minimum energy pathway. The very small values of the limiting potential and activation barrier indicate that CO2 reduction reaction on borophene is both thermodynamically and kinetically feasible. Overall, our work provides insight that the metal free and metallic borophene can be used as an excellent electrocatalyst for CO2 reduction.
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CO2 fixation and conversion are desirable to solve the exceeding CO2 emission. Traditional CO2 cycloaddition needs strict conditions, co-catalyst and solvent, causing energy intensive and complex recycle process. In this work, an ...
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CO2 fixation and conversion are desirable to solve the exceeding CO2 emission. Traditional CO2 cycloaddition needs strict conditions, co-catalyst and solvent, causing energy intensive and complex recycle process. In this work, an integrated ionic polymers (IPs) and phosphomolybdate (PM012) co-modified CuTCPPCo MOF all-in-one composite catalyst (PBPCT*) is designed for solar driven, solvent-free and co-catalyst-free CO2 cycloaddition. The PMo_(12) clusters and IPs offer abundant active sites for reactants activation and ring opening. The activation energy significandy decreases from 66.36 kJ·mol~(-1) of CuTCPPCo MOF to 49.47 kJ·mol~(-1) of PBPCT*, and guarantees higher efficient with 99.2% yield of styrene carbonate at 353 K for 12 h. The TOF of 580.73 h~(-1) under light density of 0.8 W/cm~2 superior to traditional heating with TOF of 473.0 h~(-1). This provides a new avenue to gather all the advantages in one catalyst, furnishing a promising approach for reducing CO2 emission and utilization.
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Herein, we report the adoption of adjustable composition nitrogen-rich units via introduction of diverse amine groups to an unsaturated metal organic framework, MIL-100(Cr), and the application of the products obtained as novel ca...
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Herein, we report the adoption of adjustable composition nitrogen-rich units via introduction of diverse amine groups to an unsaturated metal organic framework, MIL-100(Cr), and the application of the products obtained as novel catalysts in the aspect of CO2 cycloaddition reactions to afford cyclic carbonates in the absence of co catalyst and solvent under mild conditions (60 degrees C, 1 MPa). Incorporation of amine groups to the frameworks leads to substantial increment in the catalytic performance of the structures. The concomitant presence of acidic and basic sites in the structure causes great conversion and selectivity in cycloaddition reactions even for large and bulky epoxides. The comparison of various groups of amines (2-aminopyridine, 1,2-phenylene diamine, 3aminopyridine and ethylene diamine) incorporated on the surface with different orientations demonstrates the effect of the orientation type in catalytic activity. CO2 gas sorption measurement helps to better understand the process of catalytic activity. The pristine MOF is unable to progress the reaction without addition of co-catalyst.
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Co-pyrolysis of water hyacinth (Eichhornia crassipes) and HDPE is a commercially effective method to mitigate the pressure of environmental pollution and the problem of invasive alien species. In this paper, the thermal behavior a...
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Co-pyrolysis of water hyacinth (Eichhornia crassipes) and HDPE is a commercially effective method to mitigate the pressure of environmental pollution and the problem of invasive alien species. In this paper, the thermal behavior and kinetic evaluation of the two raw materials with or without catalysts have been investigated. The mechanism of catalytic pyrolysis was also investigated by analyzing the free radicals generated during catalytic pyrolysis. The results showed that the heating rates had a negligible effect on the pyrolysis process. The addition of HDPE could reduce the formation of char and be conducive to the complete reaction with the higher value of the comprehensive pyrolysis index (CPI). The sample containing 75% water hyacinth exhibited the strongest synergistic effect in co-pyrolysis, with the lowest value of the difference between experimental and theoretical weight loss (Delta W) and activation energy among the co-pyrolysis samples. However, the sample with 25% water hyacinth showed an inhibiting effect due to the positive value of Delta W in the main decomposition temperature. Whereas the sample containing HZSM-5 had the lowest Delta W and activation energy compared to the blends without catalysts indicating that the presence of HZSM-5 was conducive to the synergistic effect in co-pyrolysis. The promotion was then demonstrated to be due to the abundance of free radicals generated in the catalytic process. This paper aims to provide some suggestions on the solution for the alleviation of environmental and energy crisis.
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In this study, a facile one-step method via pyrolysis was used to prepare nitrogen self-doped metal free catalysts derived from inexpensive biomass-chitin for an electrochemical CO2 reduction reaction (CO2RR). The microstructure, ...
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In this study, a facile one-step method via pyrolysis was used to prepare nitrogen self-doped metal free catalysts derived from inexpensive biomass-chitin for an electrochemical CO2 reduction reaction (CO2RR). The microstructure, surface area, defect and N type in the catalysts were analyzed by BET, Raman, XPS, SEM and TEM. The sustainable chitin-based electrocatalyst prepared under optimized conditions has a surface area of 1972 m2/g and can convert CO2 into CO with FECO of ~90% at a potential of ?0.59 V (vs. RHE). This good CO2RR performance results from plentiful active sites due to a high surface area, rich ultra-micropores that are beneficial to CO2 adsorption, abundant mesopores for CO2 transport improvement, a high content of pyridinic and graphitic nitrogen that is favorable for a CO2 reduction reaction and a low interfacial charge transfer resistance leading to a rapid electron transfer rate from the catalyst to CO2. This study shows the feasibility of N self-doped biomass-derived catalysts for CO2RR with the potential for large-scale industrial applications.
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Searching environmentally friendly and low-cost catalysts for CO2 reduction is critical for the development of sustainable energy and environmental technolo_gies. In this work, we report a novel heterointerface between graphene an...
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Searching environmentally friendly and low-cost catalysts for CO2 reduction is critical for the development of sustainable energy and environmental technolo_gies. In this work, we report a novel heterointerface between graphene and BN nanotubes or nanoribbons as efficient catalysts for CO2 reduction with high activity and selectivity. The active sites are found to be at the C-N interfaces of graphene-BN (G-BN) and their excellent catalytic performance is derived from the surface curvature effect. The density functional theory (DFT) results reveal that the most energy favorable pathway for the formation of CH3OH is * + CO2 ! *COOH ! *CO ! *OCH ! *OCH2 ! *OCH3 ! *CH3OH ! * + CH3OH. And the formation of CH4 is through * + CO2 ! *COOH ! *CO ! *OCH ! *OCH2 ! *OCH3 ! *O + CH4 ! *OH + CH4 ! *H2O + CH4 pathway. Moreover, the calculated results further demonstrate that for the smaller index of G-BN nanotubes, such as G-BN (3), the formation of CH3OH product is much easier than the *O intermediate and CH4 molecule due to the lower free energy change. However, for the higher indexed G-BN nanotubes, after forming *OCH3 intermediate, the generation of *O and CH4 molecule is more feasible, particularly for G-BN (9), and the calculated limit ing potential is only ?0.42 V, which is higher than the best Cu-based materials, like ?0.93 V on Cu(111), and ?0.74 V on Cu (211). This metal free heterostructure is confirmed to facilitate CO2 conversion with high activity and selectivity, demonstrating a great potential as a new type of catalyst for CO2 reduction.
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In the context of global warming and the future circular economy, chemical fixation of carbon dioxide (CO2) is a fast-developing research area because gaseous CO2 could be trapped and converted into value-added products, industria...
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In the context of global warming and the future circular economy, chemical fixation of carbon dioxide (CO2) is a fast-developing research area because gaseous CO2 could be trapped and converted into value-added products, industrial chemicals and pharmaceuticals. The latest advancements focus on homogeneous and heterogeneous catalysts, yet drawbacks of high price, complicated design and difficult recovery need to be circumvented. Although the catalyst-free concept has been extensively used in synthetic chemistry, this paradigm remains underexplored in the domain of CO2 conversion. Therefore, here we review catalyst-free chemical and photochemical fixation of CO2 for the manufacture of products such as ureas, carbamates, oxazolidinones, quinazoline-2,4(1H,3H)-diones, benzimidazoles, 1,6-dioxospiro/1,6-dioxaspiro derivatives, polymers, N-formamides, N-methylamines and carboxylic acids. Noteworthy, the catalyst-free conversion of CO2 can be accomplished in water or in solvent-less conditions. We also discuss the reaction mechanisms leading to the formation of CO2-derived products in the absence of any catalyst or additives.
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Abstract SSZ‐13, small‐pore zeolite with chabazite (CHA) topology, exhibits outstanding performance in gas adsorption‐separation and catalysis. However, most of the studies on SSZ‐13 zeolite are limited to the powder form. In ...
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Abstract SSZ‐13, small‐pore zeolite with chabazite (CHA) topology, exhibits outstanding performance in gas adsorption‐separation and catalysis. However, most of the studies on SSZ‐13 zeolite are limited to the powder form. In practical application, the SSZ‐13 zeolite should be shaped with a certain amount of inert binder into technical form resulting in reduced performance. Herein, shaped binder‐free SSZ‐13 zeolite was prepared by treating the extruded SSZ‐13/SiO2 sample with amantadine solution under hydrothermal conditions, to crystallize the SiO2 binder into the zeolite phase. The characterization and DFT calculation results point out that the recrystallization of SiO2 binder in shaped SSZ‐13 into zeolite crystal could improve the physical and chemical properties. Enhanced CO2 adsorption capacity and catalysis performance in CO2‐assisted oxidative dehydrogenation of ethane and propane were also found on the shaped binder‐free SSZ‐13 zeolite.
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