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2018 Volume 39 Issue 12
2018, 39(12):
Abstract:
2018, 39(12): 1861-1868
doi: 10.1016/S1872-2067(18)63144-4
Abstract:
Through several waves of technological research and un-matched innovation strategies, bio-catalysis has been widely used at the industrial level. Because of the value of enzymes, methods for producing value-added compounds and industrially-relevant fine chemicals through biological methods have been developed. A broad spectrum of numerous biochemical pathways is catalyzed by enzymes, including enzymes that have not been identified. However, low catalytic efficacy, low stability, inhibition by non-cognate substrates, and intolerance to the harsh reaction conditions required for some chemical processes are considered as major limitations in applied bio-catalysis. Thus, the development of green catalysts with multi-catalytic features along with higher efficacy and induced stability are important for bio-catalysis. Implementation of computational science with metabolic engineering, synthetic biology, and machine learning routes offers novel alternatives for engineering novel catalysts. Here, we describe the role of synthetic biology and metabolic engineering in catalysis. Machine learning algorithms for catalysis and the choice of an algorithm for predicting protein-ligand interactions are discussed. The importance of molecular docking in predicting binding and catalytic functions is reviewed. Finally, we describe future challenges and perspectives.
Through several waves of technological research and un-matched innovation strategies, bio-catalysis has been widely used at the industrial level. Because of the value of enzymes, methods for producing value-added compounds and industrially-relevant fine chemicals through biological methods have been developed. A broad spectrum of numerous biochemical pathways is catalyzed by enzymes, including enzymes that have not been identified. However, low catalytic efficacy, low stability, inhibition by non-cognate substrates, and intolerance to the harsh reaction conditions required for some chemical processes are considered as major limitations in applied bio-catalysis. Thus, the development of green catalysts with multi-catalytic features along with higher efficacy and induced stability are important for bio-catalysis. Implementation of computational science with metabolic engineering, synthetic biology, and machine learning routes offers novel alternatives for engineering novel catalysts. Here, we describe the role of synthetic biology and metabolic engineering in catalysis. Machine learning algorithms for catalysis and the choice of an algorithm for predicting protein-ligand interactions are discussed. The importance of molecular docking in predicting binding and catalytic functions is reviewed. Finally, we describe future challenges and perspectives.
2018, 39(12): 1869-1880
doi: 10.1016/S1872-2067(18)63153-5
Abstract:
Co2C-based catalysts with SiO2, γ-Al2O3, and carbon nanotubes (CNTs) as support materials were prepared and evaluated for the Fischer-Tropsch to olefin (FTO) reaction. The combination of catalytic performance and structure characterization indicates that the cobalt-support interaction has a great influence on the Co2C morphology and catalytic performance. The CNT support facilitates the formation of a CoMn composite oxide during calcination, and Co2C nanoprisms were observed in the spent catalysts, resulting in a product distribution that greatly deviates from the classical Anderson-Schulz-Flory (ASF) distribution, where only 2.4 C% methane was generated. The Co3O4 phase for SiO2-and γ-Al2O3-supported catalysts was observed in the calcined sample. After reduction, CoO, MnO, and low-valence CoMn composite oxide were generated in the γ-Al2O3-supported sample, and both Co2C nanospheres and nanoprisms were identified in the corresponding spent catalyst. However, only separated phases of CoO and MnO were found in the reduced sample supported by SiO2, and Co2C nanospheres were detected in the spent catalyst without the evidence of any Co2C nanoprisms. The Co2C nanospheres led to a relatively high methane selectivity of 5.8 C% and 12.0 C% of the γ-Al2O3-and SiO2-supported catalysts, respectively. These results suggest that a relatively weak cobalt-support interaction is necessary for the formation of the CoMn composite oxide during calcination, which benefits the formation of Co2C nanoprisms with promising catalytic performance for the sustainable production of olefins via syngas.
Co2C-based catalysts with SiO2, γ-Al2O3, and carbon nanotubes (CNTs) as support materials were prepared and evaluated for the Fischer-Tropsch to olefin (FTO) reaction. The combination of catalytic performance and structure characterization indicates that the cobalt-support interaction has a great influence on the Co2C morphology and catalytic performance. The CNT support facilitates the formation of a CoMn composite oxide during calcination, and Co2C nanoprisms were observed in the spent catalysts, resulting in a product distribution that greatly deviates from the classical Anderson-Schulz-Flory (ASF) distribution, where only 2.4 C% methane was generated. The Co3O4 phase for SiO2-and γ-Al2O3-supported catalysts was observed in the calcined sample. After reduction, CoO, MnO, and low-valence CoMn composite oxide were generated in the γ-Al2O3-supported sample, and both Co2C nanospheres and nanoprisms were identified in the corresponding spent catalyst. However, only separated phases of CoO and MnO were found in the reduced sample supported by SiO2, and Co2C nanospheres were detected in the spent catalyst without the evidence of any Co2C nanoprisms. The Co2C nanospheres led to a relatively high methane selectivity of 5.8 C% and 12.0 C% of the γ-Al2O3-and SiO2-supported catalysts, respectively. These results suggest that a relatively weak cobalt-support interaction is necessary for the formation of the CoMn composite oxide during calcination, which benefits the formation of Co2C nanoprisms with promising catalytic performance for the sustainable production of olefins via syngas.
2018, 39(12): 1881-1889
doi: 10.1016/S1872-2067(18)63154-7
Abstract:
A straightforward and efficient protocol for dearomatizing indoles is described. The reaction, catalyzed by an inexpensive Co(Ⅲ)/Zn(Ⅱ) catalyst, starts from easily accessible N-pyrimidinyl indoles and ene-yne ketones. Mild reaction conditions, high diastereoselectivity, a broad substrate scope, effective functional group tolerance, and reasonable to remarkable yields were observed.
A straightforward and efficient protocol for dearomatizing indoles is described. The reaction, catalyzed by an inexpensive Co(Ⅲ)/Zn(Ⅱ) catalyst, starts from easily accessible N-pyrimidinyl indoles and ene-yne ketones. Mild reaction conditions, high diastereoselectivity, a broad substrate scope, effective functional group tolerance, and reasonable to remarkable yields were observed.
2018, 39(12): 1890-1900
doi: 10.1016/S1872-2067(18)63152-3
Abstract:
A carbon-doped TiO2/fly ash support (C-TiO2/FAS) composite photocatalyst was successfully synthesized through sol impregnation and subsequent carbonization. The carbon dopants were derived from the organic species generated during the synthesis of the C-TiO2/FAS composite. A series of analytical techniques, such as scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), were used to characterize the properties of the prepared samples. The results indicated that C-TiO2 was successfully coated on the FAS surface. Coupling between C-TiO2 and FAS resulted in the formation of Si-O-C and Al-O-Ti bonds at their interface. The formation of Si-O-C and Al-O-Ti bonds gave rise to a positive shift of the valence band edge of C-TiO2 and enhanced its oxidation capability of photogenerated holes as well as photodegradation efficiency of methyl orange. Moreover, the C-TiO2/FAS photocatalyst exhibited favorable reusability and separability. This work may provide a new route for tuning the electronic band structure of TiO2.
A carbon-doped TiO2/fly ash support (C-TiO2/FAS) composite photocatalyst was successfully synthesized through sol impregnation and subsequent carbonization. The carbon dopants were derived from the organic species generated during the synthesis of the C-TiO2/FAS composite. A series of analytical techniques, such as scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), were used to characterize the properties of the prepared samples. The results indicated that C-TiO2 was successfully coated on the FAS surface. Coupling between C-TiO2 and FAS resulted in the formation of Si-O-C and Al-O-Ti bonds at their interface. The formation of Si-O-C and Al-O-Ti bonds gave rise to a positive shift of the valence band edge of C-TiO2 and enhanced its oxidation capability of photogenerated holes as well as photodegradation efficiency of methyl orange. Moreover, the C-TiO2/FAS photocatalyst exhibited favorable reusability and separability. This work may provide a new route for tuning the electronic band structure of TiO2.
2018, 39(12): 1901-1909
doi: 10.1016/S1872-2067(18)63137-7
Abstract:
Development of efficient heterostructured photocatalysts that respond to visible light remains a considerable challenge. We herein show the synthesis of ZnIn2S4/carbon quantum dot hybrid photocatalysts with flowerlike microspheres via a facile solvothermal method. The ZnIn2S4/carbon quantum dot flowerlike microspheres display enhanced photocatalytic and photoelectrochemical activity compared with that of pure ZnIn2S4. With a content of only 0.5 wt% carbon quantum dots, 93% of Cr(VI) is reduced under visible-light irradiation at 40 min. As a co-catalyst, the carbon quantum dots improve the light absorption and lengthen the lifetime of charge carriers, consequently enhancing the photocatalytic and photoelectrochemical activity.
Development of efficient heterostructured photocatalysts that respond to visible light remains a considerable challenge. We herein show the synthesis of ZnIn2S4/carbon quantum dot hybrid photocatalysts with flowerlike microspheres via a facile solvothermal method. The ZnIn2S4/carbon quantum dot flowerlike microspheres display enhanced photocatalytic and photoelectrochemical activity compared with that of pure ZnIn2S4. With a content of only 0.5 wt% carbon quantum dots, 93% of Cr(VI) is reduced under visible-light irradiation at 40 min. As a co-catalyst, the carbon quantum dots improve the light absorption and lengthen the lifetime of charge carriers, consequently enhancing the photocatalytic and photoelectrochemical activity.
2018, 39(12): 1910-1918
doi: 10.1016/S1872-2067(18)63140-7
Abstract:
A novel visible light-responsive homogeneous catalyst based on Bi2WO6 quantum dots (QDs-BWO)/Bi2WO6 nanosheets (N-BWO) was successfully fabricated through a simple hydrothermal method. A variety of techniques were employed to investigate the morphology, structure, and electronic properties of the samples. The photocatalytic performance of the QDs/N-BWO materials was investigated by monitoring the degradation of 4-chlorophenol and rhodamine B under visible light irradiation. The as-fabricated QDs/N-BWO materials showed higher photocatalytic activity than both QDs-BWO and N-BWO. The results reveal that the incorporation of the QDs improved the separation efficiency of electron-hole pairs, leading to enhanced photocatalytic activity. Moreover, the results of quenching experiments show that·O2- species played a major role in the degradation process. This work provides an important reference for the fabrication of homogeneous catalysts with high performance in the degradation of different types of pollutants.
A novel visible light-responsive homogeneous catalyst based on Bi2WO6 quantum dots (QDs-BWO)/Bi2WO6 nanosheets (N-BWO) was successfully fabricated through a simple hydrothermal method. A variety of techniques were employed to investigate the morphology, structure, and electronic properties of the samples. The photocatalytic performance of the QDs/N-BWO materials was investigated by monitoring the degradation of 4-chlorophenol and rhodamine B under visible light irradiation. The as-fabricated QDs/N-BWO materials showed higher photocatalytic activity than both QDs-BWO and N-BWO. The results reveal that the incorporation of the QDs improved the separation efficiency of electron-hole pairs, leading to enhanced photocatalytic activity. Moreover, the results of quenching experiments show that·O2- species played a major role in the degradation process. This work provides an important reference for the fabrication of homogeneous catalysts with high performance in the degradation of different types of pollutants.
2018, 39(12): 1919-1928
doi: 10.1016/S1872-2067(18)63143-2
Abstract:
Catalytic oxidation at room temperature is recognized as the most promising method for formaldehyde (HCHO) removal. Pt-based catalysts are the optimal catalyst for HCHO decomposition at room temperature. Herein, flower-like hierarchical Pt/NiAl-LDHs catalysts with different[Ni2+]/[Al3+] molar ratios were synthesized via hydrothermal method followed by NaBH4 reduction of Pt precursor at room temperature. The flower-like hierarchical Pt/NiAl-LDHs were composed of interlaced nanoplates and metallic Pt nanoparticles (NPs) approximately 3-4 nm in diameter were loaded on the surface of the Pt/NiAl-LDHs with high dispersion. The as-prepared Pt/NiAl21 nanocomposite was highly efficient in catalyzing oxidation of HCHO into CO2 at room temperature. The high activity of the hierarchical Pt/NiAl21 nanocomposite was maintained after seven recycle tests, suggesting the high stability of the catalyst. Based on in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies, a reaction mechanism was put forward about HCHO decomposition at room temperature. This work provides new insights into designing and fabricating high-performance catalysts for efficient indoor air purification.
Catalytic oxidation at room temperature is recognized as the most promising method for formaldehyde (HCHO) removal. Pt-based catalysts are the optimal catalyst for HCHO decomposition at room temperature. Herein, flower-like hierarchical Pt/NiAl-LDHs catalysts with different[Ni2+]/[Al3+] molar ratios were synthesized via hydrothermal method followed by NaBH4 reduction of Pt precursor at room temperature. The flower-like hierarchical Pt/NiAl-LDHs were composed of interlaced nanoplates and metallic Pt nanoparticles (NPs) approximately 3-4 nm in diameter were loaded on the surface of the Pt/NiAl-LDHs with high dispersion. The as-prepared Pt/NiAl21 nanocomposite was highly efficient in catalyzing oxidation of HCHO into CO2 at room temperature. The high activity of the hierarchical Pt/NiAl21 nanocomposite was maintained after seven recycle tests, suggesting the high stability of the catalyst. Based on in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies, a reaction mechanism was put forward about HCHO decomposition at room temperature. This work provides new insights into designing and fabricating high-performance catalysts for efficient indoor air purification.
2018, 39(12): 1929-1941
doi: 10.1016/S1872-2067(18)63146-8
Abstract:
CeO2,Ce1-xZrxO2, and Ce1-xYxO2-δ(x=0.25, 0.50, 0.75, and 1.00) have been rapidly synthesized to estimate their catalytic behavior in decomposing CH3SH. The role of oxygen vacancies, and the relationship between the oxygen species and catalytic properties of CeO2 andZr-doped and Y-doped ceria-based materials are investigated in detail. Combining the observed catalytic performance with the characterization results, it can be deemed that surface lattice oxygenplays a critical role in methanethiol catalytic conversion over cerium oxides. Ce0.75Zr0.25O2 shows higher catalytic activity for CH3SH decomposition due to the large amount of surface lattice oxygen,readily available oxygen species, and excellent redox properties. Ce0.75Y0.25O2-δ displays better catalytic stability owing to the greater number of oxygen vacancies that would promote bulk lattice oxygen migration to the surface of the catalyst in order to replenish surface lattice oxygen. In addition, the results show that the difference in chemical valence between Ce and the heteroatoms would strongly influence the amount of surface lattice oxygen as well as the mobility of bulk-phase oxygen in these catalysts, thus affecting their activity and stability.
CeO2,Ce1-xZrxO2, and Ce1-xYxO2-δ(x=0.25, 0.50, 0.75, and 1.00) have been rapidly synthesized to estimate their catalytic behavior in decomposing CH3SH. The role of oxygen vacancies, and the relationship between the oxygen species and catalytic properties of CeO2 andZr-doped and Y-doped ceria-based materials are investigated in detail. Combining the observed catalytic performance with the characterization results, it can be deemed that surface lattice oxygenplays a critical role in methanethiol catalytic conversion over cerium oxides. Ce0.75Zr0.25O2 shows higher catalytic activity for CH3SH decomposition due to the large amount of surface lattice oxygen,readily available oxygen species, and excellent redox properties. Ce0.75Y0.25O2-δ displays better catalytic stability owing to the greater number of oxygen vacancies that would promote bulk lattice oxygen migration to the surface of the catalyst in order to replenish surface lattice oxygen. In addition, the results show that the difference in chemical valence between Ce and the heteroatoms would strongly influence the amount of surface lattice oxygen as well as the mobility of bulk-phase oxygen in these catalysts, thus affecting their activity and stability.
2018, 39(12): 1942-1950
doi: 10.1016/S1872-2067(18)63133-X
Abstract:
Great efforts have been devoted to the developing of simple, efficient and stable heterogeneous catalysts for the styrene epoxidation reaction (SER). Metal oxides can be of industrial importance by offering an economic and green route for selectively converting styrene into styrene oxide (SO). Herein, by treating the pristine porous 2D Co3O4 sheets with NaBH4 solution, a novel hierarchical structure, i.e., 0D Co3O4 nanoparticles decorated on 2D porous Co3O4 sheets, was obtained. This simple solution reduction strategy not only realizes the morphology evolution, but also induces the modification of the valence states of metal ions and the simultaneous generation of surface oxygen vacancies. The hierarchical 0D/2D Co3O4 hybrids rich in oxygen vacancies (OV-Co3O4) exhibit a much better SER performance than the Co3O4 sheets (P-Co3O4), with the yield of SO more than doubled. The excellent catalytic performance of the OV-Co3O4 can be ascribed to the synergistic effects regarding the hierarchical porous structure, the modification of surface chemical composition and the creation of surface oxygen vacancies.
Great efforts have been devoted to the developing of simple, efficient and stable heterogeneous catalysts for the styrene epoxidation reaction (SER). Metal oxides can be of industrial importance by offering an economic and green route for selectively converting styrene into styrene oxide (SO). Herein, by treating the pristine porous 2D Co3O4 sheets with NaBH4 solution, a novel hierarchical structure, i.e., 0D Co3O4 nanoparticles decorated on 2D porous Co3O4 sheets, was obtained. This simple solution reduction strategy not only realizes the morphology evolution, but also induces the modification of the valence states of metal ions and the simultaneous generation of surface oxygen vacancies. The hierarchical 0D/2D Co3O4 hybrids rich in oxygen vacancies (OV-Co3O4) exhibit a much better SER performance than the Co3O4 sheets (P-Co3O4), with the yield of SO more than doubled. The excellent catalytic performance of the OV-Co3O4 can be ascribed to the synergistic effects regarding the hierarchical porous structure, the modification of surface chemical composition and the creation of surface oxygen vacancies.
2018, 39(12): 1951-1959
doi: 10.1016/S1872-2067(18)63155-9
Abstract:
An amorphous CoSnO3@rGO nanocomposite fabricated using a surfactant-assisted assembly method combined with thermal treatment served as a catalyst for non-aqueous lithium-oxygen (Li-O2) batteries. In contrast to the specific surface area of the bare CoSnO3 nanoboxes (104.3 m2 g-1), the specific surface area of the CoSnO3@rGO nanocomposite increased to approximately 195.8 m2 g-1 and the electronic conductivity also improved. The increased specific surface area provided more space for the deposition of Li2O2, while the improved electronic conductivity accelerated the decomposition of Li2O2. Compared to bare CoSnO3, the overpotential reduced by approximately 20 and 60 mV at current densities of 100 and 500 mA g-1 when CoSnO3@rGO was used as the catalyst. A Li-O2 battery using a CoSnO3@rGO nanocomposite as the cathode catalyst cycled indicated a superior cyclic stability of approximately 130 cycles at a current density of 200 mA g-1 with a limited capacity of 1000 mAh g-1, which is 25 cycles more than that of the bare amorphous CoSnO3 nanoboxes.
An amorphous CoSnO3@rGO nanocomposite fabricated using a surfactant-assisted assembly method combined with thermal treatment served as a catalyst for non-aqueous lithium-oxygen (Li-O2) batteries. In contrast to the specific surface area of the bare CoSnO3 nanoboxes (104.3 m2 g-1), the specific surface area of the CoSnO3@rGO nanocomposite increased to approximately 195.8 m2 g-1 and the electronic conductivity also improved. The increased specific surface area provided more space for the deposition of Li2O2, while the improved electronic conductivity accelerated the decomposition of Li2O2. Compared to bare CoSnO3, the overpotential reduced by approximately 20 and 60 mV at current densities of 100 and 500 mA g-1 when CoSnO3@rGO was used as the catalyst. A Li-O2 battery using a CoSnO3@rGO nanocomposite as the cathode catalyst cycled indicated a superior cyclic stability of approximately 130 cycles at a current density of 200 mA g-1 with a limited capacity of 1000 mAh g-1, which is 25 cycles more than that of the bare amorphous CoSnO3 nanoboxes.
2018, 39(12): 1960-1970
doi: 10.1016/S1872-2067(18)63147-X
Abstract:
The coupled reaction of methyl acetate and n-hexane was carried out over a HZSM-5 catalyst. In addition to a thermal coupling effect, systematic variations in the product distribution were also observed in the coupled system. The bezene-toluene-xylene (BTX) selectivity was remarkably improved while the H2, CO, and CO2 selectivity decreased. Rapid deactivation of the catalyst was observed, caused by the extremely high reactivity of methyl acetate, which was alleviated after adding n-hexane. These results indicated that a coupling effect exists in this system. A detailed pathway for the coupled system is suggested based on the analysis of the surface species, carbonaceous species deposited on the catalyst, as well as the product selectivity changes. The good match between the "hydrogen deficiency" of methyl acetate and the "hydrogen richness" of n-hexane is consistent with the observed coupling effect.
The coupled reaction of methyl acetate and n-hexane was carried out over a HZSM-5 catalyst. In addition to a thermal coupling effect, systematic variations in the product distribution were also observed in the coupled system. The bezene-toluene-xylene (BTX) selectivity was remarkably improved while the H2, CO, and CO2 selectivity decreased. Rapid deactivation of the catalyst was observed, caused by the extremely high reactivity of methyl acetate, which was alleviated after adding n-hexane. These results indicated that a coupling effect exists in this system. A detailed pathway for the coupled system is suggested based on the analysis of the surface species, carbonaceous species deposited on the catalyst, as well as the product selectivity changes. The good match between the "hydrogen deficiency" of methyl acetate and the "hydrogen richness" of n-hexane is consistent with the observed coupling effect.
2018, 39(12): 1971-1979
doi: 10.1016/S1872-2067(18)63158-4
Abstract:
Fischer-Tropsch synthesis (FTS) has the potential to be a powerful strategy for producing liquid fuels from syngas if highly selective catalysts can be developed. Herein, a series of iron nanoparticle catalysts encapsulated by nitrogen-doped graphitic carbon were prepared by a one-step pyrolysis of a ferric L-glutamic acid complex. The FeC-800 catalyst pyrolyzed at 800℃ showed excellent catalytic activity (239.4 μmolCO gFe-1 s-1), high C5-C11 selectivity (49%), and good stability in FTS. The high dispersion of ferric species combined with a well-encapsulated structure can effectively inhibit the migration of iron nanoparticles during the reaction process, which is beneficial for high activity and good stability. The nitrogen-doped graphitic carbon shell can act as an electron donor to the iron particles, thus promoting CO activation and expediting the formation of Fe5C2, which is the key factor for obtaining high C5-C11 selectivity.
Fischer-Tropsch synthesis (FTS) has the potential to be a powerful strategy for producing liquid fuels from syngas if highly selective catalysts can be developed. Herein, a series of iron nanoparticle catalysts encapsulated by nitrogen-doped graphitic carbon were prepared by a one-step pyrolysis of a ferric L-glutamic acid complex. The FeC-800 catalyst pyrolyzed at 800℃ showed excellent catalytic activity (239.4 μmolCO gFe-1 s-1), high C5-C11 selectivity (49%), and good stability in FTS. The high dispersion of ferric species combined with a well-encapsulated structure can effectively inhibit the migration of iron nanoparticles during the reaction process, which is beneficial for high activity and good stability. The nitrogen-doped graphitic carbon shell can act as an electron donor to the iron particles, thus promoting CO activation and expediting the formation of Fe5C2, which is the key factor for obtaining high C5-C11 selectivity.
