Carbon dioxide capture and reduction(CCR)process emerges as an efficient catalytic strategy for CO_(2)capture and conversion to valuable chemicals.K-promoted Cu/Al_(2)O_(3)catalysts exhibited promising CO_(2)capture e...Carbon dioxide capture and reduction(CCR)process emerges as an efficient catalytic strategy for CO_(2)capture and conversion to valuable chemicals.K-promoted Cu/Al_(2)O_(3)catalysts exhibited promising CO_(2)capture efficiency and highly selective conversion to syngas(CO+H_(2)).The dynamic nature of the Cu-K system at reaction conditions complicates the identification of the catalytically active phase and surface sites.The present work aims at more precise understanding of the roles of the potassium and copper and the contribution of the metal oxide support.Whileγ-Al_(2)O_(3)guarantees high dispersion and destabilisation of the potassium phase,potassium and copper act synergistically to remove CO_(2)from diluted streams and promote fast regeneration of the active phase for CO_(2)capture releasing CO while passing H_(2).A temperature of 350℃is found necessary to activate H_(2)dissociation and generate the active sites for CO_(2)capture.The effects of synthesis parameters on the CCR activity are also described by combination of ex-situ characterisation of the materials and catalytic testing.展开更多
The plasma catalytic degradation of o-xylene in simulated air was improved by loading low amounts of Pt,Pd,or Au onto Co_(3)O_(4).At room temperature,o-xylene conversion and CO_(x)selectivity using a0.1 wt%Pt/Co_(3)O_...The plasma catalytic degradation of o-xylene in simulated air was improved by loading low amounts of Pt,Pd,or Au onto Co_(3)O_(4).At room temperature,o-xylene conversion and CO_(x)selectivity using a0.1 wt%Pt/Co_(3)O_(4)catalyst reached 98.9%and 80%,and the energy efficiency was at the top level in comparison with values in the literature.A stable o-xylene degradation performance could be obtained by online regenerating the heat-insulated reactor with a high energy density.After characterization,it was found that the loading of nanosized Pt not only increased the Co^(3+)/Co^(2+)ratio,where the Co^(3+)benefitted the formation of reactive oxygen species,but also conduced Pt^(0)to oxygen activation,resulting in effective promotion of complete o-xylene oxidation.Operando plasma diffuse reflectance infrared Fourier transform spectroscopy demonstrated the complete o-xylene oxidation and proved that Pt played a key role in the complete oxidation of o-xylene.展开更多
Diesel particulate matter(DPM)and hydrocarbons(HCs)emitted from diesel engines have a negative affect on air quality and human health.Catalysts for oxidative removal of DPM and HCs are currently used universally but t...Diesel particulate matter(DPM)and hydrocarbons(HCs)emitted from diesel engines have a negative affect on air quality and human health.Catalysts for oxidative removal of DPM and HCs are currently used universally but their low removal efficiency at low temperatures is a problem.In this study,Cu-doped CeO_(2) loaded on Al_(2)O_(3) coupled with plasma was used to enhance low-temperature oxidation of DPM and HCs.Removals of DPM and HCs at 200℃ using the catalyst were as high as 90%with plasma but below 30%without plasma.Operando plasma diffuse reflectance infrared Fourier transform spectroscopy coupled with mass spectrometry was conducted to reveal the functional mechanism of the oxygen species in the DPM oxidation process.It was found that Cu-CeO_(2) can promote the formation of adsorbed oxygen(M^(+)-O_(2)^(-))and terminal oxygen(M=O),which can react with DPM to form carbonates that are easily converted to gaseous CO_(2).Our results provide a practical plasma catalysis technology to obtain simultaneous removals of DPM and HCs at low temperatures.M+O-2Diesel particulate matter(DPM)and hydrocarbons(HCs)emitted from diesel engines have a negative affect on air quality and human health.Catalysts for oxidative removal of DPM and HCs are currently used universally but their low removal efficiency at low temperatures is a problem.In this study,Cu-doped CeO_(2) loaded on Al_(2)O_(3) coupled with plasma was used to enhance low-temperature oxidation of DPM and HCs.Removals of DPM and HCs at 200°C using the catalyst were as high as 90%with plasma but below 30%without plasma.Operando plasma diffuse reflectance infrared Fourier transform spectroscopy coupled with mass spectrometry was conducted to reveal the functional mechanism of the oxygen species in the DPM oxidation process.It was found that Cu–CeO_(2) can promote the formation of adsorbed oxygen(–)and terminal oxygen(M=O),which can react with DPM to form carbonates that are easily converted to gaseous CO_(2).Our results provide a practical plasma catalysis technology to obtain simultaneous removals of DPM and HCs at low temperatures.展开更多
Gold(Au)nanostructures(NSs)have been widely employed as cocatalysts to improve the photoactivity of semiconductor materials,while a systematic summary of the engineering approaches of Au NSs to maximize the solar-to-f...Gold(Au)nanostructures(NSs)have been widely employed as cocatalysts to improve the photoactivity of semiconductor materials,while a systematic summary of the engineering approaches of Au NSs to maximize the solar-to-fuel conversion efficiency is still lacking.In this review,the recently developed strategies for elevating the overall photocatalytic performance of Au-based catalysts and the deep physical chemistry mechanisms are highlighted.Firstly,the synthetic approaches of Au NSs are summarized,followed by an elaboration on their multiple functions in improving photoactivity.Afterward,modification strategies of Au NSs used to enhance the photocatalytic efficiency of Au-semiconductor composites,including controlling the Au NSs morphology,size,crystal phase,defect engineering,alloying with different metals,modulating interfacial interaction,and introducing an external field,are summarized and discussed independently.Additionally,advanced characterization techniques that can provide insights into the charge dynamics of the photocatalysts are introduced.Finally,we share our opinion on the challenges and outline potentially promising opportunities and directions for efficient Au-based photocatalysis research moving forward.We sincerely look forward to this review can deliver insightful views to design efficient Au-based photocatalysts and spur certain innovations to other metal-based catalysts.展开更多
The rising CO2 level, population boom and increasing energy demand prompts the need of an efficient and sustainable solution to tackle the global warming issue. Reduction of greenhouse gas（GHG） emission through the ...The rising CO2 level, population boom and increasing energy demand prompts the need of an efficient and sustainable solution to tackle the global warming issue. Reduction of greenhouse gas（GHG） emission through the conversion of detrimental CO2 into methanol is one of the most promising solutions for optimising economic and resource efficiency. The utilisation of the abundant and sustainable sunlight to replace thermal and electric energy for CO2 conversion to valuable chemicals is a highly sustainable process and attracted much research interests. Herein, we summarised the catalytic methods for CO2 conversion to methanol, reviewed the photocatalytic properties and efficient photocatalysts, as well as their performance. Carbon [78TD$IF]quantum dots（CQDs） as a new member of the carbon nanomaterials family have attracted increasing attention owing to their excellent photoluminescence property, light harvesting capability, charge recombination suppression and effective electron transport ability. This paper highlighted the multifaceted roles of CQDs in photocatalytic reactions. To this end, the challenges and future directions of CQDs-based photocatalysts have been outlined.展开更多
Surface-functionalized nitrogen/carbon co-doped polymorphic TiO_(2) phase junction nanoparticles uniformly distributed in porous carbon matrix were synthesized by a simple one-step pyrolysis of titanium based metal-or...Surface-functionalized nitrogen/carbon co-doped polymorphic TiO_(2) phase junction nanoparticles uniformly distributed in porous carbon matrix were synthesized by a simple one-step pyrolysis of titanium based metal-organic framework(MOF),NH_(2)-MIL^(-1)25(Ti) at 700℃ under water vapour atmosphere.Introducing water vapour during the pyrolysis of NH_(2)-MIL^(-1)25(Ti) not only functionalizes the derived porous carbon matrix with carboxyl groups but also forms additional oxygen-rich N like interstitial/intraband states lying above the valence band of TiO2 along with the self-doped carbo n,which further narrows the energy band gaps of polymorphic TiO2 nanoparticles that enhance photocatalytic charge transfer efficiency.Without co-catalyst,sample N-C-TiO2/CArW demonstrates H_(2) evolution activity of 426 μmol gcat-1h^(-1),which remarkably outperforms commercial TiO_(2)(P-25) and N-C-TiO_(2)/CAr with a 5-fold and 3-fold H_(2) generation,respectively.This study clearly shows that water vapour atmosphere during the pyrolysis increases the hydrophilicity of the Ti-MOF derived composites by functionalizing porous carbon matrix with carboxylic groups,as well as enhancing the electrical conductivity and charge transfer efficiency due to the formation of additional localized oxygen-rich N like interstitial/intraband states.This work also demonstrates that by optimizing the anatase-rutile phase composition of the TiO2 polymorphs,tuning the energy band gaps by N/C co-doping and functionalizing the porous carbon matrix in the N-C-TiO2/C nanocomposites,the photocatalytic H_(2) generation activity can be further enhanced.展开更多
TiO2‐supported Pd‐Sb bimetallic catalysts were prepared and evaluated for the direct synthesis of H2O2 at ambient pressure.The addition of Sb to Pd significantly enhanced catalytic performance,and a Pd50Sb catalyst ...TiO2‐supported Pd‐Sb bimetallic catalysts were prepared and evaluated for the direct synthesis of H2O2 at ambient pressure.The addition of Sb to Pd significantly enhanced catalytic performance,and a Pd50Sb catalyst showed the greatest selectivity of up to 73%.Sb promoted the dispersion of Pd on TiO2,as evidenced by transmission electron microscopy and X‐ray diffraction.X‐ray photoelectron spectroscopy indicated that the oxidation of Pd was suppressed by Sb.In addition,Sb2O3 layers were formed and partially wrapped the surfaces of Pd catalysts,thus suppressing the activation of H2 and subsequent hydrogenation of H2O2.In situ diffuse reflection infrared Fourier transform spectroscopy for CO adsorption suggested that Sb homogenously located on the surface of Pd‐Sb catalysts and isolated contiguous Pd sites,resulting in the rise of the ratio of Pd monomer sites that are favorable for H2O2 formation.As a result,the Sb modified Pd surfaces significantly enhanced the non‐dissociative activation of O2 and H2O2 selectivity.展开更多
N-F-codoped TiO2 （NFTO） photocatalysts were synthesized by a simple sol-gel process with tetrabutyl titanate （Ti（OBu）4 ） as the precursor of TiO 2 and ammonium fluoride （NH4 F） as the source of N and F.The syn...N-F-codoped TiO2 （NFTO） photocatalysts were synthesized by a simple sol-gel process with tetrabutyl titanate （Ti（OBu）4 ） as the precursor of TiO 2 and ammonium fluoride （NH4 F） as the source of N and F.The synthesized photocatalysts were investigated by X- ray diffraction （XRD）,X-ray photoelectron spectroscopy （XPS）,ultraviolet-visible diffuse reflectance spectroscopy （UV-Vis DRS） and photodegradation reaction tests of 4-chlorophenol under visible light irradiation to understand the relationship between the structure of NFTO catalyst and corresponding photocatalytic activity.The crystal phase and particle size of catalysts were found to be largely affected by the calcination temperature.In addition,N-F-codoping could inhibit phase transition of TiO2 from anatase to rutile.The presence of N and F atoms in the lattice of TiO2 is responsible for the visible light catalytic activity.In UV-Vis DRS tests,the spectrum of NFTO exhibited red shift compared with Degussa P25 and the band gap was reduced to around 2.92 eV.Under optimal calcination temperature and dopant concentration conditions,the NFTO photocatalyst exhibited the highest activity in the photodegradation reaction tests of 4-chlorophenol under visible light irradiation with a degradation rate of 75.84%.Besides,the 5-recycle test showed that NFTO photocatalyst could be reused and its activity kept stable under visible light irradiation.展开更多
Post-synthetic treatment of high-silica as-made ZSM-5 with organic template in the micropores was explored to reduce/remove the external surface acid density of ZSM-5. It is found that Na_2H_2 EDTA treatment can selec...Post-synthetic treatment of high-silica as-made ZSM-5 with organic template in the micropores was explored to reduce/remove the external surface acid density of ZSM-5. It is found that Na_2H_2 EDTA treatment can selectively remove the surface Al atoms, but generates new acid sites（likely silanol nests） on the external surface. H_3PO_4 treatment is unable to remove surface Al atoms, while small amount of P is left on the external surface, which effectively decreases the acid density. The catalytic performance of the resultant materials is evaluated in the methanol conversion reaction. H_3PO_4 treatment can effectively improve both the catalytic lifetime and the stability of propene selectivity.This occurs due to a combination of the increased tolerance to the external coke deposition and the depressed coking rate（reduced side reactions）. Na_2H_2 EDTA treatment only prolongs the catalytic lifetime, resulting from the improved tolerance to the external coke deposition. Under the optimized H_3PO_4 treatment condition, the resultant ZSM-5 gives a catalytic lifetime of about 1.5 times longer than the precursor. Moreover, the propene selectivity is improved, showing a slight increasing trend until the deactivation.展开更多
The SAPO‐34 catalysts were modified with metal cations by different processes(conventional ion exchange(CIE),template‐assisted ion incorporation(TII)and alcoholic ion exchange(AIE)),systematically characterized by X...The SAPO‐34 catalysts were modified with metal cations by different processes(conventional ion exchange(CIE),template‐assisted ion incorporation(TII)and alcoholic ion exchange(AIE)),systematically characterized by XRD,XRF,N2 adsorption‐desorption,UV‐VIS,H2‐TPR,EPR,SEM,EDX,XPS,NH3‐TPD,1H NMR and IGA,and applied in MTO reaction.The metal cations incorporation introduces extra diffusion hindrance by metallic species located in the cavity of SAPO‐34.In particular,the Zn cations‐modified SAPO‐34 catalysts exhibit core‐shell like structure,with Si‐rich and Zn‐rich sublayer near the external surface,which favors the coke deposition at the beginning of MTO reaction,exerts marked impact on the diffusion of the generated products with relatively large molecular size(e.g.propylene),and significantly increases the selectivity to ethylene and the ratio of ethylene to propene in the MTO reaction.展开更多
Methylcyclopentenyl cations(MCP+)have been regarded as active intermediates during methanol conversion,however,their function mode in the reaction are still uncertain.In our recent report,trimethylcyclopentenyl cation...Methylcyclopentenyl cations(MCP+)have been regarded as active intermediates during methanol conversion,however,their function mode in the reaction are still uncertain.In our recent report,trimethylcyclopentenyl cation(triMCP+)and its deprotonated counterpart(trimethylcyclopentadiene,tri MCP)were directly captured on H-RUB-50 catalyst with small cavity by the aid of in situ 13C MAS NMR spectroscopy,and their higher catalytic reactivity were clarified by 12C/13C-CH3OH isotopic switch experiment.In this contribution,an alternative route-cyclopentadienes-based cycle was applied on methanol conversion catalyzed on the H-RUB-50,in which ethene was produced with the participation of tri MCP+as critical intermediate.Then the cyclopentadienes-based cycle was predicted to be energetically favorable for ethene formation by density functional theory(DFT)calculations.The energetic comparison of paring mechanism in the aromatics-based cycle and cyclopentadienes-based cycle with the involvements of trimethylcyclopentadienyl(tri MCPdi+)and tri MCP+as the corresponding active intermediates suggests that cyclopentadienes-based cycle is a feasible route for ethene formation.Furthermore,this work highlights the importance of the steric constraint and the host-vip interaction induced by the zeolite with cavity structure in the formation of intermediates and reaction pathway.展开更多
The main challenge in the dehydration of glycerol to acrolein lies in overcoming catalystdeactivation and improving the selectivity to acrolein. The relationship between theacidity in the mesoporous channels and catal...The main challenge in the dehydration of glycerol to acrolein lies in overcoming catalystdeactivation and improving the selectivity to acrolein. The relationship between theacidity in the mesoporous channels and catalytic performance of glycerol dehydration israrely reported. In this work, to investigate the influence of acidity in the mesoporouschannels of hierarchical ZSM-5 catalysts on the dehydration of glycerol to acrolein, a seriesof hierarchical ZSM-5 zeolites with comparable mesoporous volume and mesoporous sizebut different acid properties in mesopores have been successfully prepared via alkalinetreatment. The sample with the abundant mesoporosity and highest acidity display thebest performance.展开更多
The SAPO-34 catalyst was fine-tuned with zinc cations through a straightforward template-assisted ion incorporation (TH) process, without the necessary template pre-removal and the preparation of NH4- SAPO-34 intermed...The SAPO-34 catalyst was fine-tuned with zinc cations through a straightforward template-assisted ion incorporation (TH) process, without the necessary template pre-removal and the preparation of NH4- SAPO-34 intermediate, which is more facile, efficient and cost-effective than the conventional ion exchange process. The template-assisted zinc cations incorporated SAPO-34 catalysts were characterized by XRD, XRF, N2 adsorption-desorption, XPS, SEM, EDX,NMR, respectively. Enhanced selectivity to ethylene and ratio of ethylene to propylene in MTO reaction are observed over the zinc cations modified SAPO-34 catalysts, due to the facilitated formation of lower methylbenzenes that favour the ethylene gen eration, as well as the increased diffusion hindrance originated from the zinc cations incorporation and the facil让ated generation of aromatics compound.展开更多
Direct conversion of syngas to aromatics has great potential to decrease fossil fuel dependence.Here,a unique structured hybrid catalyst composed of Fe_(3)O_(4) nanoparticles intimately dispersed inside an acidic zeol...Direct conversion of syngas to aromatics has great potential to decrease fossil fuel dependence.Here,a unique structured hybrid catalyst composed of Fe_(3)O_(4) nanoparticles intimately dispersed inside an acidic zeolite is developed.1 to 4 nm sized Fe_(3)O_(4) nanoparticles end up evenly dispersed in an acidic and slightly mesoporous Al-ZSM-5 based on Fe_(3)O_(4) restructuring during co-hydro thermal synthesis using organosilane modification.A very high aromatic productivity of 214 mmolaromatics h^(-1) gFe^(-1) can be obtained with a remarkable 62%aromatic selectivity in hydrocarbons.This catalyst has excellent sintering resistance ability and maintains stable aromatics production over 570 h.The synthetic insights that postulate a mechanism for the metastable oxide-zeolite reorganization during hydrothermal synthesis could serve as a generic route to sinter-resistant oxide-zeolite composite materials with uniform,well-dispersed oxide nanoparticles in close intimacy with-and partially confined in-a zeolite matrix.展开更多
The effect of N_(2)discharge products on cyclohexane degradation over a MnO_(2)/γ-Al_(2)O_(3)catalyst has been evaluated by feeding N_(2)discharge products to the catalyst using a specially designed dielectric barrie...The effect of N_(2)discharge products on cyclohexane degradation over a MnO_(2)/γ-Al_(2)O_(3)catalyst has been evaluated by feeding N_(2)discharge products to the catalyst using a specially designed dielectric barrier discharge reactor.At a reaction temperature of 100℃,the cyclohexane conversion increased from 2.46%(without N_(2)discharge products)to 26.3%(with N_(2)discharge products).N-and O-containing by-product(3,4-dehydroproline)was found on the catalyst surface using gas chromatograph-mass spectrometry identification,in which C=N–C and C=N–H bonds were also confirmed from x-ray photoelectron spectroscopy analysis results.Operando analysis results using diffuse reflectance infrared Fourier transform spectroscopy revealed that N atoms can react with surface H_(2)O possibly to NH and OH reactive species that have reactivities to promote CO oxidation to CO_(2).The mechanism of N-atom-driven cyclohexane degradation to CO and CO_(2)is proposed.展开更多
Identification of the catalyst characteristics correlating with the key performance parameters including selectivity and stability is key to the rational catalyst design. Herein we focused on the identification of pro...Identification of the catalyst characteristics correlating with the key performance parameters including selectivity and stability is key to the rational catalyst design. Herein we focused on the identification of property-performance relationships in the methanol-to-olefin(MTO) process by studying in detail the catalytic behaviour of MFI, MEL and their respective intergrowth zeolites. The detailed material characterization reveals that both the high production of propylene and butylenes and the large Me OH conversion capacity correlate with the enrichment of lattice Al sites in the channels of the pentasil structure as identified by 27 Al MAS NMR and 3-methylpentane cracking results. The lack of correlation between MTO performance and other catalyst characteristics, such as crystal size, presence of external Brønsted acid sites and Al pairing suggests their less pronounced role in defining the propylene selectivity. Our analysis reveals that catalyst deactivation is rather complex and is strongly affected by the enrichment of lattice Al in the intersections, the overall Al-content, and crystal size. The intergrowth of MFI and MEL phases accelerates the catalyst deactivation rate.展开更多
Ozone(O_(3)) generated by a dielectric barrier discharge(DBD) is widely used in various industrial processes. In this study, NaCl aqueous solution was used as a novel electric power transmission electrode in a DBD rea...Ozone(O_(3)) generated by a dielectric barrier discharge(DBD) is widely used in various industrial processes. In this study, NaCl aqueous solution was used as a novel electric power transmission electrode in a DBD reactor(instead of a traditional metal electrode) for highly efficient ozone generation. The results demonstrated that a high O_(3) yield of 242 g k Wh^(-1) with a concentration of 14.6 g m^(-3)O_(3) was achieved. The power transmission mechanism works because NaCl aqueous solution behaves as a capacitor when an alternating pulse voltage below 8 k Hz is used.Compared with the resistance of the discharge barrier and discharge space, the resistance of NaCl aqueous solution can be ignored, which ensures that O_(3) is generated efficiently. It is expected that O_(3) generation using NaCl aqueous solution as a novel electrode in a DBD reactor could be an alternative technology with good application prospects.展开更多
Developing a widely-used reactive force field is meaningful to explore the fundamental reaction mechanism on gas-surface chemical reaction dynamics due to its very high computational efficiency. We here present a stud...Developing a widely-used reactive force field is meaningful to explore the fundamental reaction mechanism on gas-surface chemical reaction dynamics due to its very high computational efficiency. We here present a study of hydrogen and its deuterated molecules dissociation on Pd surfaces based on a full-dimensional potential energy surface （PES） constructed by using a simple second moment approximation reactive force field （SMA RFF）. Although the descriptions of the adsorbate-substrate interaction contain only the dissociation reaction of H2/Pd（111） system, a good transferability of SMA potential energy surface （PES） is shown to investigate the hydrogen dissociation on Pd（100）. Our simulation results show that, the dissociation probabilities of H2 and its deuterated molecules on Pd（111） and Pd（100） surfaces keep non-monotonous variations with respect to the incident energy Ei, which is in good agreement with the previous ab initio molecular dynamics. Furthermore, for the oriented molecules, the dissociation probabilities of the oriented H2 （D2 and T2） molecule have the same orientation dependence behavior as those oriented HD （HT and DT） molecules.展开更多
The high-temperature(HT) and low-temperature(LT) hydrothermal stabilities of molecular-sieve-based catalysts are important for the selective catalytic reduction of NOx with ammonia(NH3-SCR). In this paper, we report a...The high-temperature(HT) and low-temperature(LT) hydrothermal stabilities of molecular-sieve-based catalysts are important for the selective catalytic reduction of NOx with ammonia(NH3-SCR). In this paper, we report a catalyst, Cu2+ loading SAPO-17, synthesized using cyclohexylamine(CHA), which is commercially available and inexpensive and is utilized in NH3-SCR reduction for the first time. After systematic investigations on the optimization of Si and Cu2+ contents, it was concluded that Cu-SAPO-17-8.0%-0.22 displays favorable catalytic performance, even after being heated at 353 K for 24 h and at 973 K for 16 h. Moreover, the locations of CHAs, host–vip interaction and the Bronsted acid sites were explored by Rietveld refinement against powder X-ray diffraction data of as-made SAPO-17-8.0%. The refinement results showed that two CHAs exist within one eri cage and that the protonated CHA forms a hydrogen bond with O4, which indicates that the proton bonding with O4 will form the Bronsted acid site after the calcination.展开更多
文摘Carbon dioxide capture and reduction(CCR)process emerges as an efficient catalytic strategy for CO_(2)capture and conversion to valuable chemicals.K-promoted Cu/Al_(2)O_(3)catalysts exhibited promising CO_(2)capture efficiency and highly selective conversion to syngas(CO+H_(2)).The dynamic nature of the Cu-K system at reaction conditions complicates the identification of the catalytically active phase and surface sites.The present work aims at more precise understanding of the roles of the potassium and copper and the contribution of the metal oxide support.Whileγ-Al_(2)O_(3)guarantees high dispersion and destabilisation of the potassium phase,potassium and copper act synergistically to remove CO_(2)from diluted streams and promote fast regeneration of the active phase for CO_(2)capture releasing CO while passing H_(2).A temperature of 350℃is found necessary to activate H_(2)dissociation and generate the active sites for CO_(2)capture.The effects of synthesis parameters on the CCR activity are also described by combination of ex-situ characterisation of the materials and catalytic testing.
基金supported by National Natural Science Foundation of China(No.12075037)Research and Application Service Platform Project of API Manufacturing Environmental Protection and Safety Technology in China(No.2020-0107-3-1)。
文摘The plasma catalytic degradation of o-xylene in simulated air was improved by loading low amounts of Pt,Pd,or Au onto Co_(3)O_(4).At room temperature,o-xylene conversion and CO_(x)selectivity using a0.1 wt%Pt/Co_(3)O_(4)catalyst reached 98.9%and 80%,and the energy efficiency was at the top level in comparison with values in the literature.A stable o-xylene degradation performance could be obtained by online regenerating the heat-insulated reactor with a high energy density.After characterization,it was found that the loading of nanosized Pt not only increased the Co^(3+)/Co^(2+)ratio,where the Co^(3+)benefitted the formation of reactive oxygen species,but also conduced Pt^(0)to oxygen activation,resulting in effective promotion of complete o-xylene oxidation.Operando plasma diffuse reflectance infrared Fourier transform spectroscopy demonstrated the complete o-xylene oxidation and proved that Pt played a key role in the complete oxidation of o-xylene.
基金supported by National Natural Science Foundation of China(nos 12075037 and 22206013)。
文摘Diesel particulate matter(DPM)and hydrocarbons(HCs)emitted from diesel engines have a negative affect on air quality and human health.Catalysts for oxidative removal of DPM and HCs are currently used universally but their low removal efficiency at low temperatures is a problem.In this study,Cu-doped CeO_(2) loaded on Al_(2)O_(3) coupled with plasma was used to enhance low-temperature oxidation of DPM and HCs.Removals of DPM and HCs at 200℃ using the catalyst were as high as 90%with plasma but below 30%without plasma.Operando plasma diffuse reflectance infrared Fourier transform spectroscopy coupled with mass spectrometry was conducted to reveal the functional mechanism of the oxygen species in the DPM oxidation process.It was found that Cu-CeO_(2) can promote the formation of adsorbed oxygen(M^(+)-O_(2)^(-))and terminal oxygen(M=O),which can react with DPM to form carbonates that are easily converted to gaseous CO_(2).Our results provide a practical plasma catalysis technology to obtain simultaneous removals of DPM and HCs at low temperatures.M+O-2Diesel particulate matter(DPM)and hydrocarbons(HCs)emitted from diesel engines have a negative affect on air quality and human health.Catalysts for oxidative removal of DPM and HCs are currently used universally but their low removal efficiency at low temperatures is a problem.In this study,Cu-doped CeO_(2) loaded on Al_(2)O_(3) coupled with plasma was used to enhance low-temperature oxidation of DPM and HCs.Removals of DPM and HCs at 200°C using the catalyst were as high as 90%with plasma but below 30%without plasma.Operando plasma diffuse reflectance infrared Fourier transform spectroscopy coupled with mass spectrometry was conducted to reveal the functional mechanism of the oxygen species in the DPM oxidation process.It was found that Cu–CeO_(2) can promote the formation of adsorbed oxygen(–)and terminal oxygen(M=O),which can react with DPM to form carbonates that are easily converted to gaseous CO_(2).Our results provide a practical plasma catalysis technology to obtain simultaneous removals of DPM and HCs at low temperatures.
基金financially supported by the National Natural Science Foundation of China(21902132)the Research Foundation-Flanders(1280021N,1242922N,1298323N)。
文摘Gold(Au)nanostructures(NSs)have been widely employed as cocatalysts to improve the photoactivity of semiconductor materials,while a systematic summary of the engineering approaches of Au NSs to maximize the solar-to-fuel conversion efficiency is still lacking.In this review,the recently developed strategies for elevating the overall photocatalytic performance of Au-based catalysts and the deep physical chemistry mechanisms are highlighted.Firstly,the synthetic approaches of Au NSs are summarized,followed by an elaboration on their multiple functions in improving photoactivity.Afterward,modification strategies of Au NSs used to enhance the photocatalytic efficiency of Au-semiconductor composites,including controlling the Au NSs morphology,size,crystal phase,defect engineering,alloying with different metals,modulating interfacial interaction,and introducing an external field,are summarized and discussed independently.Additionally,advanced characterization techniques that can provide insights into the charge dynamics of the photocatalysts are introduced.Finally,we share our opinion on the challenges and outline potentially promising opportunities and directions for efficient Au-based photocatalysis research moving forward.We sincerely look forward to this review can deliver insightful views to design efficient Au-based photocatalysts and spur certain innovations to other metal-based catalysts.
文摘The rising CO2 level, population boom and increasing energy demand prompts the need of an efficient and sustainable solution to tackle the global warming issue. Reduction of greenhouse gas（GHG） emission through the conversion of detrimental CO2 into methanol is one of the most promising solutions for optimising economic and resource efficiency. The utilisation of the abundant and sustainable sunlight to replace thermal and electric energy for CO2 conversion to valuable chemicals is a highly sustainable process and attracted much research interests. Herein, we summarised the catalytic methods for CO2 conversion to methanol, reviewed the photocatalytic properties and efficient photocatalysts, as well as their performance. Carbon [78TD$IF]quantum dots（CQDs） as a new member of the carbon nanomaterials family have attracted increasing attention owing to their excellent photoluminescence property, light harvesting capability, charge recombination suppression and effective electron transport ability. This paper highlighted the multifaceted roles of CQDs in photocatalytic reactions. To this end, the challenges and future directions of CQDs-based photocatalysts have been outlined.
基金EPSRC CDT in Metamaterials at University of Exeter and Leverhulme Trust(RPG-2018-320) for financial support。
文摘Surface-functionalized nitrogen/carbon co-doped polymorphic TiO_(2) phase junction nanoparticles uniformly distributed in porous carbon matrix were synthesized by a simple one-step pyrolysis of titanium based metal-organic framework(MOF),NH_(2)-MIL^(-1)25(Ti) at 700℃ under water vapour atmosphere.Introducing water vapour during the pyrolysis of NH_(2)-MIL^(-1)25(Ti) not only functionalizes the derived porous carbon matrix with carboxyl groups but also forms additional oxygen-rich N like interstitial/intraband states lying above the valence band of TiO2 along with the self-doped carbo n,which further narrows the energy band gaps of polymorphic TiO2 nanoparticles that enhance photocatalytic charge transfer efficiency.Without co-catalyst,sample N-C-TiO2/CArW demonstrates H_(2) evolution activity of 426 μmol gcat-1h^(-1),which remarkably outperforms commercial TiO_(2)(P-25) and N-C-TiO_(2)/CAr with a 5-fold and 3-fold H_(2) generation,respectively.This study clearly shows that water vapour atmosphere during the pyrolysis increases the hydrophilicity of the Ti-MOF derived composites by functionalizing porous carbon matrix with carboxylic groups,as well as enhancing the electrical conductivity and charge transfer efficiency due to the formation of additional localized oxygen-rich N like interstitial/intraband states.This work also demonstrates that by optimizing the anatase-rutile phase composition of the TiO2 polymorphs,tuning the energy band gaps by N/C co-doping and functionalizing the porous carbon matrix in the N-C-TiO2/C nanocomposites,the photocatalytic H_(2) generation activity can be further enhanced.
基金supported by the National Natural Science Foundation of China(91534127,U1463205)the Innovation Scientists and Technicians Troop Construction Projects of Henan Provincethe Chinese Education Ministry 111 Project(B08021)~~
文摘TiO2‐supported Pd‐Sb bimetallic catalysts were prepared and evaluated for the direct synthesis of H2O2 at ambient pressure.The addition of Sb to Pd significantly enhanced catalytic performance,and a Pd50Sb catalyst showed the greatest selectivity of up to 73%.Sb promoted the dispersion of Pd on TiO2,as evidenced by transmission electron microscopy and X‐ray diffraction.X‐ray photoelectron spectroscopy indicated that the oxidation of Pd was suppressed by Sb.In addition,Sb2O3 layers were formed and partially wrapped the surfaces of Pd catalysts,thus suppressing the activation of H2 and subsequent hydrogenation of H2O2.In situ diffuse reflection infrared Fourier transform spectroscopy for CO adsorption suggested that Sb homogenously located on the surface of Pd‐Sb catalysts and isolated contiguous Pd sites,resulting in the rise of the ratio of Pd monomer sites that are favorable for H2O2 formation.As a result,the Sb modified Pd surfaces significantly enhanced the non‐dissociative activation of O2 and H2O2 selectivity.
基金supported by the Scienceand Technology Project of Education Commission of Chongqing of China(No.KJ110709)the Key Science Project of Ministry of Education of China(No.2008119)+1 种基金the Colleges and Universities Innovation Team Project of Chongqing of China(No.KJTD201020)the Scienceand Technology Project of Engineering Research Centre for Waste Oil,Ministry of Education of China(No.FYKJ2009012)
文摘N-F-codoped TiO2 （NFTO） photocatalysts were synthesized by a simple sol-gel process with tetrabutyl titanate （Ti（OBu）4 ） as the precursor of TiO 2 and ammonium fluoride （NH4 F） as the source of N and F.The synthesized photocatalysts were investigated by X- ray diffraction （XRD）,X-ray photoelectron spectroscopy （XPS）,ultraviolet-visible diffuse reflectance spectroscopy （UV-Vis DRS） and photodegradation reaction tests of 4-chlorophenol under visible light irradiation to understand the relationship between the structure of NFTO catalyst and corresponding photocatalytic activity.The crystal phase and particle size of catalysts were found to be largely affected by the calcination temperature.In addition,N-F-codoping could inhibit phase transition of TiO2 from anatase to rutile.The presence of N and F atoms in the lattice of TiO2 is responsible for the visible light catalytic activity.In UV-Vis DRS tests,the spectrum of NFTO exhibited red shift compared with Degussa P25 and the band gap was reduced to around 2.92 eV.Under optimal calcination temperature and dopant concentration conditions,the NFTO photocatalyst exhibited the highest activity in the photodegradation reaction tests of 4-chlorophenol under visible light irradiation with a degradation rate of 75.84%.Besides,the 5-recycle test showed that NFTO photocatalyst could be reused and its activity kept stable under visible light irradiation.
文摘Post-synthetic treatment of high-silica as-made ZSM-5 with organic template in the micropores was explored to reduce/remove the external surface acid density of ZSM-5. It is found that Na_2H_2 EDTA treatment can selectively remove the surface Al atoms, but generates new acid sites（likely silanol nests） on the external surface. H_3PO_4 treatment is unable to remove surface Al atoms, while small amount of P is left on the external surface, which effectively decreases the acid density. The catalytic performance of the resultant materials is evaluated in the methanol conversion reaction. H_3PO_4 treatment can effectively improve both the catalytic lifetime and the stability of propene selectivity.This occurs due to a combination of the increased tolerance to the external coke deposition and the depressed coking rate（reduced side reactions）. Na_2H_2 EDTA treatment only prolongs the catalytic lifetime, resulting from the improved tolerance to the external coke deposition. Under the optimized H_3PO_4 treatment condition, the resultant ZSM-5 gives a catalytic lifetime of about 1.5 times longer than the precursor. Moreover, the propene selectivity is improved, showing a slight increasing trend until the deactivation.
文摘The SAPO‐34 catalysts were modified with metal cations by different processes(conventional ion exchange(CIE),template‐assisted ion incorporation(TII)and alcoholic ion exchange(AIE)),systematically characterized by XRD,XRF,N2 adsorption‐desorption,UV‐VIS,H2‐TPR,EPR,SEM,EDX,XPS,NH3‐TPD,1H NMR and IGA,and applied in MTO reaction.The metal cations incorporation introduces extra diffusion hindrance by metallic species located in the cavity of SAPO‐34.In particular,the Zn cations‐modified SAPO‐34 catalysts exhibit core‐shell like structure,with Si‐rich and Zn‐rich sublayer near the external surface,which favors the coke deposition at the beginning of MTO reaction,exerts marked impact on the diffusion of the generated products with relatively large molecular size(e.g.propylene),and significantly increases the selectivity to ethylene and the ratio of ethylene to propene in the MTO reaction.
基金the financial support from the National Natural Science Foundation of China(Nos.91745109,21703239 and 21972142)the Key Research Program of Frontier Sciences,CAS,Grant No.QYZDY-SSW-JSC024+2 种基金the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2014165)the International Partnership Program of Chinese Academy of Sciences,Grant No.121421KYSB20180007Liaoning Revitalization Talents Program(XLYC1807227)。
文摘Methylcyclopentenyl cations(MCP+)have been regarded as active intermediates during methanol conversion,however,their function mode in the reaction are still uncertain.In our recent report,trimethylcyclopentenyl cation(triMCP+)and its deprotonated counterpart(trimethylcyclopentadiene,tri MCP)were directly captured on H-RUB-50 catalyst with small cavity by the aid of in situ 13C MAS NMR spectroscopy,and their higher catalytic reactivity were clarified by 12C/13C-CH3OH isotopic switch experiment.In this contribution,an alternative route-cyclopentadienes-based cycle was applied on methanol conversion catalyzed on the H-RUB-50,in which ethene was produced with the participation of tri MCP+as critical intermediate.Then the cyclopentadienes-based cycle was predicted to be energetically favorable for ethene formation by density functional theory(DFT)calculations.The energetic comparison of paring mechanism in the aromatics-based cycle and cyclopentadienes-based cycle with the involvements of trimethylcyclopentadienyl(tri MCPdi+)and tri MCP+as the corresponding active intermediates suggests that cyclopentadienes-based cycle is a feasible route for ethene formation.Furthermore,this work highlights the importance of the steric constraint and the host-vip interaction induced by the zeolite with cavity structure in the formation of intermediates and reaction pathway.
基金The work was supported by the Australian Research Council Discovery Projects(grant no.DP150103842,DP180104010,DE190101618)the SOAR Fellowship,and the Sydney Nano Grand Challenge from the University of Sydney。
文摘The main challenge in the dehydration of glycerol to acrolein lies in overcoming catalystdeactivation and improving the selectivity to acrolein. The relationship between theacidity in the mesoporous channels and catalytic performance of glycerol dehydration israrely reported. In this work, to investigate the influence of acidity in the mesoporouschannels of hierarchical ZSM-5 catalysts on the dehydration of glycerol to acrolein, a seriesof hierarchical ZSM-5 zeolites with comparable mesoporous volume and mesoporous sizebut different acid properties in mesopores have been successfully prepared via alkalinetreatment. The sample with the abundant mesoporosity and highest acidity display thebest performance.
基金the National Natural Science Foundation of China(21603223,91745109,91545104,21473182,91334205)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2014165)for financial support
文摘The SAPO-34 catalyst was fine-tuned with zinc cations through a straightforward template-assisted ion incorporation (TH) process, without the necessary template pre-removal and the preparation of NH4- SAPO-34 intermediate, which is more facile, efficient and cost-effective than the conventional ion exchange process. The template-assisted zinc cations incorporated SAPO-34 catalysts were characterized by XRD, XRF, N2 adsorption-desorption, XPS, SEM, EDX,NMR, respectively. Enhanced selectivity to ethylene and ratio of ethylene to propylene in MTO reaction are observed over the zinc cations modified SAPO-34 catalysts, due to the facilitated formation of lower methylbenzenes that favour the ethylene gen eration, as well as the increased diffusion hindrance originated from the zinc cations incorporation and the facil让ated generation of aromatics compound.
基金supported financially by the National Natural Science Foundation of China(51776206)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2017BT01N092)+4 种基金the National Key R&D Program of China(2018YFB1501504)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX20_0095)the Fundamental Research Funds for the Central Universities(3203002104D)the Research Foundation-Flanders(FWO,grant 12E8617N)for funding and KU Leuven grant C14/20/086visiting scholar(2017-20202)at the Guangzhou Institute of Energy Conversion,Chinese Academy of Sciences。
文摘Direct conversion of syngas to aromatics has great potential to decrease fossil fuel dependence.Here,a unique structured hybrid catalyst composed of Fe_(3)O_(4) nanoparticles intimately dispersed inside an acidic zeolite is developed.1 to 4 nm sized Fe_(3)O_(4) nanoparticles end up evenly dispersed in an acidic and slightly mesoporous Al-ZSM-5 based on Fe_(3)O_(4) restructuring during co-hydro thermal synthesis using organosilane modification.A very high aromatic productivity of 214 mmolaromatics h^(-1) gFe^(-1) can be obtained with a remarkable 62%aromatic selectivity in hydrocarbons.This catalyst has excellent sintering resistance ability and maintains stable aromatics production over 570 h.The synthetic insights that postulate a mechanism for the metastable oxide-zeolite reorganization during hydrothermal synthesis could serve as a generic route to sinter-resistant oxide-zeolite composite materials with uniform,well-dispersed oxide nanoparticles in close intimacy with-and partially confined in-a zeolite matrix.
基金National Natural Science Foundation of China(No.12075037)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX21_2873)Research and Application Service Platform Project of API Manufacturing Environmental Protection and Safety Technology in China(No.2020-0107-3-1).
文摘The effect of N_(2)discharge products on cyclohexane degradation over a MnO_(2)/γ-Al_(2)O_(3)catalyst has been evaluated by feeding N_(2)discharge products to the catalyst using a specially designed dielectric barrier discharge reactor.At a reaction temperature of 100℃,the cyclohexane conversion increased from 2.46%(without N_(2)discharge products)to 26.3%(with N_(2)discharge products).N-and O-containing by-product(3,4-dehydroproline)was found on the catalyst surface using gas chromatograph-mass spectrometry identification,in which C=N–C and C=N–H bonds were also confirmed from x-ray photoelectron spectroscopy analysis results.Operando analysis results using diffuse reflectance infrared Fourier transform spectroscopy revealed that N atoms can react with surface H_(2)O possibly to NH and OH reactive species that have reactivities to promote CO oxidation to CO_(2).The mechanism of N-atom-driven cyclohexane degradation to CO and CO_(2)is proposed.
基金supported by the BASF and the Advanced Research Center Chemical Building Blocks Consortium (ARC CBBC) for Funding under Project (2016.007.TUD)
文摘Identification of the catalyst characteristics correlating with the key performance parameters including selectivity and stability is key to the rational catalyst design. Herein we focused on the identification of property-performance relationships in the methanol-to-olefin(MTO) process by studying in detail the catalytic behaviour of MFI, MEL and their respective intergrowth zeolites. The detailed material characterization reveals that both the high production of propylene and butylenes and the large Me OH conversion capacity correlate with the enrichment of lattice Al sites in the channels of the pentasil structure as identified by 27 Al MAS NMR and 3-methylpentane cracking results. The lack of correlation between MTO performance and other catalyst characteristics, such as crystal size, presence of external Brønsted acid sites and Al pairing suggests their less pronounced role in defining the propylene selectivity. Our analysis reveals that catalyst deactivation is rather complex and is strongly affected by the enrichment of lattice Al in the intersections, the overall Al-content, and crystal size. The intergrowth of MFI and MEL phases accelerates the catalyst deactivation rate.
基金supported by National Natural Science Foundation of China (Nos. 12075037 and 22206013)the Natural Science Foundation of Jiangsu Province (No. BK20210857)the Leading Innovative Talents Cultivation Project of Changzhou City (No. CQ20210083)。
文摘Ozone(O_(3)) generated by a dielectric barrier discharge(DBD) is widely used in various industrial processes. In this study, NaCl aqueous solution was used as a novel electric power transmission electrode in a DBD reactor(instead of a traditional metal electrode) for highly efficient ozone generation. The results demonstrated that a high O_(3) yield of 242 g k Wh^(-1) with a concentration of 14.6 g m^(-3)O_(3) was achieved. The power transmission mechanism works because NaCl aqueous solution behaves as a capacitor when an alternating pulse voltage below 8 k Hz is used.Compared with the resistance of the discharge barrier and discharge space, the resistance of NaCl aqueous solution can be ignored, which ensures that O_(3) is generated efficiently. It is expected that O_(3) generation using NaCl aqueous solution as a novel electrode in a DBD reactor could be an alternative technology with good application prospects.
基金This work was supported by the National Natural Science Foundation of China （No.21506053） and Doctoral Scientific Research Foundation Project （KYY15023）.
文摘Developing a widely-used reactive force field is meaningful to explore the fundamental reaction mechanism on gas-surface chemical reaction dynamics due to its very high computational efficiency. We here present a study of hydrogen and its deuterated molecules dissociation on Pd surfaces based on a full-dimensional potential energy surface （PES） constructed by using a simple second moment approximation reactive force field （SMA RFF）. Although the descriptions of the adsorbate-substrate interaction contain only the dissociation reaction of H2/Pd（111） system, a good transferability of SMA potential energy surface （PES） is shown to investigate the hydrogen dissociation on Pd（100）. Our simulation results show that, the dissociation probabilities of H2 and its deuterated molecules on Pd（111） and Pd（100） surfaces keep non-monotonous variations with respect to the incident energy Ei, which is in good agreement with the previous ab initio molecular dynamics. Furthermore, for the oriented molecules, the dissociation probabilities of the oriented H2 （D2 and T2） molecule have the same orientation dependence behavior as those oriented HD （HT and DT） molecules.
文摘The high-temperature(HT) and low-temperature(LT) hydrothermal stabilities of molecular-sieve-based catalysts are important for the selective catalytic reduction of NOx with ammonia(NH3-SCR). In this paper, we report a catalyst, Cu2+ loading SAPO-17, synthesized using cyclohexylamine(CHA), which is commercially available and inexpensive and is utilized in NH3-SCR reduction for the first time. After systematic investigations on the optimization of Si and Cu2+ contents, it was concluded that Cu-SAPO-17-8.0%-0.22 displays favorable catalytic performance, even after being heated at 353 K for 24 h and at 973 K for 16 h. Moreover, the locations of CHAs, host–vip interaction and the Bronsted acid sites were explored by Rietveld refinement against powder X-ray diffraction data of as-made SAPO-17-8.0%. The refinement results showed that two CHAs exist within one eri cage and that the protonated CHA forms a hydrogen bond with O4, which indicates that the proton bonding with O4 will form the Bronsted acid site after the calcination.
