Chemical warfare agents(CWAs)remain a persistent hazard in many parts of the world,necessitating a deeper exploration of their chemical and physical characteristics and reactions under diverse conditions.Diisopropyl m...Chemical warfare agents(CWAs)remain a persistent hazard in many parts of the world,necessitating a deeper exploration of their chemical and physical characteristics and reactions under diverse conditions.Diisopropyl methylphosphonate(DIMP),a commonly used CWA surrogate,is widely studied to enhance our understanding of CWA behavior.The prevailing thermal decomposition model for DIMP,developed approximately 25 years ago,is based on data collected in nitrogen atmospheres at temperatures ranging from 700 K to 800 K.Despite its limitations,this model continues to serve as a foundation for research across various thermal and reactive environments,including combustion studies.Our recent experiments have extended the scope of decomposition analysis by examining DIMP in both nitrogen and zero air across a lower temperature range of 175??C to 250??C.Infrared spectroscopy results under nitrogen align well with the established model;however,we observed that catalytic effects,stemming from decomposition byproducts and interactions with stainless steel surfaces,alter the reaction kinetics.In zero air environments,we observed a novel infrared absorption band.Spectral fitting suggests this band may represent a combination of propanal and acetone,while GCMS analysis points to vinyl formate and acetone as possible constituents.Although the precise identity of these new products remains unresolved,our findings clearly indicate that the existing decomposition model cannot be reliably extended to lower temperatures or non-nitrogen environments without further revisions.展开更多
Both direct and sensitized irradiations of the endo title compound lead to a decarbony- lation product,4-isopropylbiphenyl,via Norrish Type 1 reaction,while the exo isomer gives a carbene intermediate and subsequently...Both direct and sensitized irradiations of the endo title compound lead to a decarbony- lation product,4-isopropylbiphenyl,via Norrish Type 1 reaction,while the exo isomer gives a carbene intermediate and subsequently formaldehyde 2-biphenylyl isopropyl hemiacetal,which in turn gradually decomposes to dimethyl phenylbenzyl alcohol at room temperature.The triplet pathway dominates the photoreaction of the exo isomer.The singlet and triplet lifetimes of the reactant are found to be 0.29 ns and 5.4μs,respectively.~3(n,π~*),~1(n,π~*),~3(π,π~*)electronic configurations of the exo isomer and ~3(π,π~*)of the endo isomer are photochemically active,but ~1(π,π~*)of the endo isomer shows indirect photoreactivity.展开更多
Hydrocarbons are one of the important fluids within the Earth's crust,and different biotic and abitoic processes can generate hydrocarbon during geological periods.Tracing the sources and sinks of hydrocarbons can...Hydrocarbons are one of the important fluids within the Earth's crust,and different biotic and abitoic processes can generate hydrocarbon during geological periods.Tracing the sources and sinks of hydrocarbons can help us better understand the carbon cycle of the earth.In this study,an improved approach of adsorbed hydrocarbons extraction from sediments was established.The improved thermal desorption approach,compound-specific isotope analysis and position-specific isotope analysis were integrated to investigate the molecular and intramolecular isotope fractionation between trace hydrocarbon gases within sediments and geological hydrocarbon deposits.The isotopic compositions of the terminal position carbon of propane(δ^(13)C_(terminal))serves as a correlation indicator between trace hydrocarbon gases within sediments and geological hydrocarbon deposits.The tight sandstone gas from the Turpan-Hami Basin is a first case study for the application of this novel method to trace hydrocarbon origins.The results showed that the hydrocarbons in the tight sandstone gases in the study area most likely originated from humic organic matter(typeⅢkerogen)at an early mature stage.δ^(13)C_(terminal)values of the thermally desorbed propane gases from different source rocks were distinguishable and the values of the tight sandstone gases significantly overlap with those of the Lower Jurassic Sangonghe source rocks,suggesting their genetic relationship.Overall,the results provided novel position-specific carbon isotopic constraints on origins of hydrocarbons.展开更多
We report a robust pillar-layered metal-organic framework,Zn‑tfbdc‑dabco(tfbdc:tetrafluoroterephthal-ate,dabco:1,4-diazabicyclo[2.2.2]octane),featuring the fluorinated pore environment,for the preferential binding of ...We report a robust pillar-layered metal-organic framework,Zn‑tfbdc‑dabco(tfbdc:tetrafluoroterephthal-ate,dabco:1,4-diazabicyclo[2.2.2]octane),featuring the fluorinated pore environment,for the preferential binding of propane over propylene and thus highly inverse selective separation of propane/propylene mixture.The inverse propane-selective performance of Zn‑tfbdc‑dabco for the propane/propylene separation was validated by single-component gas adsorption isotherms,isosteric enthalpy of adsorption calculations,ideal adsorbed solution theory calculations,along with the breakthrough experiment.The customized fluorinated networks served as a propane-trap to form more interactions with the exposed hydrogen atoms of propane,as unveiled by the simulation studies at the molecular level.With the advantage of inverse propane-selective adsorption behavior,high adsorption capacity,good cycling stability,and low isosteric enthalpy of adsorption,Zn‑tfbdc‑dabco can be a promising candidate adsorbent for the challenging propane/propylene separation to realize one-step purification of the target propylene substance.展开更多
Propylene,a pivotal chemical feedstock,is extensively used in synthesizing high-value derivatives such as polypropylene and acrylonitrile[1].Although propylene is predominantly produced via naphtha cracking,a persiste...Propylene,a pivotal chemical feedstock,is extensively used in synthesizing high-value derivatives such as polypropylene and acrylonitrile[1].Although propylene is predominantly produced via naphtha cracking,a persistent supply-demand gap exists[2].Non-oil routes,such as propane dehydrogenation(PDH),are increasingly attractive,particularly with the availability of shale gas[3].Modern non-oxidative PDH heavily relies on Pt nanoparticle catalysts promoted with SnOx(e.g.,PtSn/Al2O3 used in Honeywell UOP's Oleflex process)[4].However,these systems suffer from inherent limitations:high Pt costs,coke formation via deep dehydrogenation,and sintering during regeneration-necessitating environmentally detrimental oxychlorination treatments to restore activity[5].展开更多
Non-oxidative dehydrogenation of propane(PDH)is an important route for large-scale on purpose propene production.Although cobalt-based catalysts are promising alternatives to currently used platinum-or chromium oxide-...Non-oxidative dehydrogenation of propane(PDH)is an important route for large-scale on purpose propene production.Although cobalt-based catalysts are promising alternatives to currently used platinum-or chromium oxide-based catalysts,their further developments are hindered by the uncertainties related to the kind of the active sites involved in the desired and side reactions.To contribute to closing such a gap,we systematically investigate the role of oxidized CoO_(x) and metallic Co0 species in the PDH reaction over catalysts based in Silicalite-1 with supported CoO_(x) species differing in their redox properties.C_(3)H_(8) pulse experiments with sub-millisecond and second resolution at pulse sizes of about 13 and 2200 nmol,respectively,combined with in-depth catalyst characterization and PDH tests at different propane conversions enabled us to understand how the reaction-induced reduction of CoO_(x) affects product selectivity.Propane readily reacts with CoO_(x) to yield propene,carbon oxides and water.The formed Co0 species show high activity to coking and cracking reactions.However,if the size of such species is below 2 nm,these undesired reactions are significantly hindered due to the coverage of the active sites by carbon-containing species.The remaining uncovered surface Co0 sites selectively dehydrogenate propane to propene.The best-performing catalyst showed higher activity than a commercial-like K-CrOx/Al_(2)O_(3) and operated durable in a series of 10 dehydrogenation/regeneration cycles under industrial relevant conditions.The space time yield of propene formation of 0.97 kg·h^(-1)·kgcat^(-1) was achieved at 550℃,52%equilibrium propane conversion and 95% propene selectivity.展开更多
Recent studies have revealed the extraordinary performance of zirconium oxide in propane dehydrogenation,which is attributed to the excellent reactivity of the coordinatively unsaturated zirconium sites(Zr_(cus))aroun...Recent studies have revealed the extraordinary performance of zirconium oxide in propane dehydrogenation,which is attributed to the excellent reactivity of the coordinatively unsaturated zirconium sites(Zr_(cus))around the oxygen vacancies.The origin of the enhanced catalytic activity of ZrO_(2)with defective tetrahedral Zr sites was examined by direct comparison with its pristine counterpart in the current study.Electronic-structure analysis revealed that electrons from oxygen removal were localized within vacancies on the defective surface,which directly attacked the C-H bond in propane.The involvement of localized electrons activates the C-H bond via back-donation to the antibonding orbital on the defective surface;conversely,charge is transferred from propane to the pristine surfaces.The barrier for the first C-H bond activation is clearly significantly reduced on the defective surfaces compared to that on the pristine surfaces,which verifies the superior activity of Zr_(cus).Notably,however,the desorption of both propene and hydrogen molecules from Zr_(cus)is more difficult due to strong binding.The calculated turnover frequency(TOF)for propene formation demonstrates that the pristine surfaces exhibit better catalytic performance at lower temperatures,whereas the defective surfaces have a larger TOF at high temperatures.However,the rate-determining step and reaction order on the defective surface differ from those on the pristine surface,which corroborates that the catalysts follow different mechanisms.A further optimization strategy was proposed to address the remaining bottlenecks in propane dehydrogenation on zirconium oxide.展开更多
Propane dehydrogenation(PDH)has emerged as a key on-purpose technology for the production of propylene,but it often depends on toxic chromium and expensive platinum catalysts,highlighting the need for environmentally ...Propane dehydrogenation(PDH)has emerged as a key on-purpose technology for the production of propylene,but it often depends on toxic chromium and expensive platinum catalysts,highlighting the need for environmentally friendly and cost-effective alternatives.In this study,we developed a facile impregnation method to fabricate unsaturated Co single-atoms with a tricoordinated Co_(1)O_(3)H_(x) structure by regulating silanol nests in purely siliceous Beta zeolites.Detailed PDH catalytic tests and characterizations revealed a positive correlation between the presence of silanol nests and enhanced catalytic activity.Additionally,the unsaturated Co single-atoms exhibited a carbon deposition rate more than an order of magnitude slower than that of Co nanoparticles.Notably,the optimized Co_(0.3%)/deAl-meso-Beta catalyst achieved a record-high propylene formation rate of 21.2 mmol_(C3H6) g_(cat)^(-1) h^(-1),with an exceptional propylene selectivity of 99.1%at 550℃.Moreover,the Co_(0.3%)/deAl-meso-Beta catalyst demonstrated excellent stability,with negligible deactivation after 5 consecutive regeneration cycles.This study emphasizes the pivotal role of silanol nests of zeolites in stabilizing and modulating the coordination environment of metallic active sites,providing valuable insights for the design of high-activity,high-stability,and low-cost PDH catalysts.展开更多
The dehydrogenation of alkanes has emerged as a vital complementary process to address the increasing global demand for olefins.A key challenge remains in the construction of novel active centers that offer superior a...The dehydrogenation of alkanes has emerged as a vital complementary process to address the increasing global demand for olefins.A key challenge remains in the construction of novel active centers that offer superior activity,stability,and cost-effectiveness.Herein,tricoordinated cobalt atoms were successfully fabricated through an in-situ ligand-protected synthesis by introducing tungsten atoms into zeolite frameworks.These unsaturated Co species efficiently activate C-H bonds while suppressing C-C bond cleavage,resulting in exceptional catalytic activity and olefin selectivity in both propane and ethane dehydrogenation reactions.The optimized Co_(0.2%)@0.01W-S-1 catalyst demonstrated an impressive propylene formation rate of 15.2 molC_(3H6)gcC h^(-1)at 823 K and an ethylene formation rate of 240.3mol_(C2H4)g_(Co)^(-1)h^(-1)at 913 K,with propylene and ethylene selectivities of 99.0%and 97.5%,respectively.These results not only significantly surpass conventional tetracoordinated Co catalysts but also rival some Pt-based catalysts under similar conditions.Importantly,the catalyst exhibited excellent stability in dehydrogenation reactions,with no significant loss in catalytic activity after five consecutive regeneration cycles.This work offers valuable insights into the design of zeolite-supported non-precious metal catalysts with high activity and durability for efficient alkane dehydrogenation.展开更多
Dispersing metals from nanoparticles to clusters is often achieved using ligand protection methods,which exhibit unique properties such as suppressing structure-sensitive side reactions.However,this method is limited ...Dispersing metals from nanoparticles to clusters is often achieved using ligand protection methods,which exhibit unique properties such as suppressing structure-sensitive side reactions.However,this method is limited by the use of different metal precursor salts corresponding to different ligands.An alternative approach,the ion exchange(IE)method,can overcome this limitation to some extent.Nevertheless,there is still an urgent need to address the stabilization of metals(especially precious metals)by using IE method.Here,we reported a Pt cluster catalyst prepared mainly by anchoring Pt atoms via O located near the framework Zn in zincosilicate zeolites and riveted by zeolite surface rings after reduction(reduced Pt/Zn-3-IE).The catalyst can achieve an initial propane conversion of 26%in a pure propane atmosphere at 550℃and shows little deactivation even after 7.5 d of operation.Moreover,the alteration of catalyst by the introduction of framework Zn was also highlighted and interpreted.展开更多
Transition metal cobalt exhibits strong activation capabilities for alkanes,however,the instability of Co sites leads to sintering and coke deposition,resulting in rapid deactivation.Hierarchical zeolites,with their d...Transition metal cobalt exhibits strong activation capabilities for alkanes,however,the instability of Co sites leads to sintering and coke deposition,resulting in rapid deactivation.Hierarchical zeolites,with their diverse pore structures and high surface areas,are used to effectively anchor metals and enhance coke tolerance.Herein,a post-treatment method using an alkaline solution was employed to synthesize meso-microporous zeolite supports,which were subsequently loaded with Co species for propane dehydrogenation catalyst.The results indicate that the application of NaOH,an inorganic base,produces supports with a larger mesopore volume and more abundant hydroxyl nests compared to TPAOH,an organic base.UV-vis,Raman,and XPS analyses reveal that Co in the 0.5Co/SN-1-0.05 catalyst is mainly in the form of tetrahedral Co^(2+),which effectively activates C-H bonds.In contrast,the 0.5Co/S-1 catalyst contains mainly Co_(3)O_(4)species.Co^(2+)supported on hierarchical zeolites shows better propane conversion(58.6%)and propylene selectivity(>96%)compared to pure silica zeolites.Coke characterization indicates that hierarchical zeolites accumulate more coke,but it is mostly in the form of easily removable disordered carbon.The mesopores in the microporous zeolite support help disperse the active Co metal and facilitate coke removal during dehydrogenation,effectively preventing deactivation from sintering and coke coverage.展开更多
Propane dehydrogenation(PDH)is a vital industrial process for producing propene,utilizing primarily Cr-based or Pt-based catalysts.These catalysts often suffer from challenges such as the toxicity of Cr,the high costs...Propane dehydrogenation(PDH)is a vital industrial process for producing propene,utilizing primarily Cr-based or Pt-based catalysts.These catalysts often suffer from challenges such as the toxicity of Cr,the high costs of noble metals like Pt,and deactivation issues due to sintering or coke formation at elevated temperatures.We introduce an exceptional Ru-based catalyst,Ru nanoparticles anchored on a nitrogendoped carbon matrix(Ru@NC),which achieves a propane conversion rate of 32.2%and a propene selectivity of 93.1%at 550°C,with minimal coke deposition and a low deactivation rate of 0.0065 h^(-1).Characterizations using techniques like TEM and XPS,along with carefully-designed controlled experiments,reveal that the notable performance of Ru@NC stems from the modified electronic state of Ru by nitrogen dopant and the microporous nature of the matrix,positioning it as a top contender among state-of-the-art PDH catalysts.展开更多
Direct converting carbon dioxide(CO_(2))and propane(C_(3)H_(8))into aromatics with high carbon utilization offers a desirable opportunity to simultaneously mitigate CO_(2)emission and adequately utilize C_(3)H_(8) in ...Direct converting carbon dioxide(CO_(2))and propane(C_(3)H_(8))into aromatics with high carbon utilization offers a desirable opportunity to simultaneously mitigate CO_(2)emission and adequately utilize C_(3)H_(8) in shale gas.Owing to their thermodynamic resistance,converting CO_(2)and C_(3)H_(8) respectively remains difficult.Here,we achieve 60.2%aromatics selectivity and 48.8%propane conversion over H-ZSM-5-25 via a zeolite-catalyzing the coupling of CO_(2)and C_(3)H_(8).Operando dual-beam FTIR spectroscopy combined with ^(13)C-labeled CO_(2)tracing experiments revealed that CO_(2)is directly involved in the generation of aromatics,with its carbon atoms selectively embedded into the aromatic ring,bypassing the reverse water-gas shift pathway.Accordingly,a cooperative aromatization mechanism is proposed.Thereinto,lactones,produced from CO_(2)and olefins,are proven to be the key intermediate.This work not only provides an opportunity for simultaneous conversion of CO_(2)and C_(3)H_(8),but also expends coupling strategy designing of CO_(2)and alkanes over acidic zeolites.展开更多
The oxidative dehydrogenation of propane to propylene using CO_(2)(CO_(2)-ODH)offers a promising route for both propylene production and CO_(2)utilization.In this study,we investigate the effect of alkali metal doping...The oxidative dehydrogenation of propane to propylene using CO_(2)(CO_(2)-ODH)offers a promising route for both propylene production and CO_(2)utilization.In this study,we investigate the effect of alkali metal doping on Pt-based catalysts in CO_(2)-ODH reactions.The optimized 0.1 KPt/S-1 catalyst achieved a high propane conversion of 48.3%,propylene selectivity of 85.5%,and CO_(2)conversion of 19.1%at a low temperature of 500℃with the Pt loading of 0.2 wt%and K loading of 0.1 wt%respectively.Characterization techniques,including high-resolution transmission electron microscope(HR-TEM),CO-diffuse reflectance infrared Fourier transform spectroscopy(CO-DRIFTS),X-ray absorption fine structure(XAFS),and X-ray Photoelectron Spectroscopy(XPS),revealed that the doping of K with Pt led to a strong interaction between potassium and platinum(Pt-KO_(x)cluster).This interaction resulted in a reduction of Pt particle size and a local enrichment of electron density around Pt atoms.These structural modifications improved the anchoring of Pt nanoparticles and enhanced Pt atom dispersion,thereby enhancing the activity of the catalyst and minimizing side reactions.Additionally,pyridine infrared(Py-IR)and temperature-programmed desorption(TPD)studies demonstrated that the prepared0.1 KPt/S-1 catalyst exhibited optimal acidity,which promoted C–H activation and facilitated the efficient adsorption and activation of CO_(2).These dual effects significantly lowered the activation energy for CO_(2)-ODH,enabling efficient dehydrogenation to propylene at a lower temperature of 500℃.This work highlights the critical role of alkali metal doping in modifying the electronic properties of Pt and optimizing catalyst acidity,which collectively contribute to the enhanced performance of the 0.1 KPt/S-1 catalyst.These findings offer valuable insights into the mechanistic pathway of CO_(2)-ODH and provide a foundation for the rational design of high-performance dehydrogenation catalysts.展开更多
Direct propane dehydrogenation(DPDH)represents a highly attractive route for on-purpose propylene production,a key building block in the petrochemical industry.In particular,among various catalytic platforms,vanadium-...Direct propane dehydrogenation(DPDH)represents a highly attractive route for on-purpose propylene production,a key building block in the petrochemical industry.In particular,among various catalytic platforms,vanadium-based catalysts have emerged as promising candidates due to their tunable properties including redox ability,surface acidity,and resistance to coking.Although the catalytic community has obtained great achievement in this area,how to promote vanadium-based catalysts towards the next step in DPDH applications like industrial-level implementations is still challenging.Moreover,there are still several controversial theories in our community,meaning it is necessary to clarify these indistinct points to pave the way for the next generation of research.Herein,the pivotal modification strategies of vanadium-based catalysts have been summarized via introducing representative works.In addition,the current unclear mechanism and research gaps,especially in the issues of deactivation and selectivity control,are also revealed so that the potential research directions are well-founded proposed.By integrating fundamental understanding and practical considerations,this review aims to inspire the further development of vanadium-based DPDH catalysts for in-depth academic research and next-generation industrial deployment.展开更多
Propane dehydrogenation(PDH)is a key process for increasing the production of propylene,which is an important part of the chemical industry.Platinum-based catalysts have emerged as efficient catalysts for this reactio...Propane dehydrogenation(PDH)is a key process for increasing the production of propylene,which is an important part of the chemical industry.Platinum-based catalysts have emerged as efficient catalysts for this reaction due to their excellent activity and selectivity.However,challenges such as high platinum cost,catalyst deactivation,and side reactions remain significant barriers to their widespread use in industry.This review provides a comprehensive overview of recent advances in platinumbased catalysts for PDH,focusing on strategies to optimize their performance.We discuss the design and synthesis of Pt-based catalysts,emphasizing the role of promoters,such as Sn,Zn,Ga,and other promoters,in improving selectivity and stability.We also explore the effects of support materials and zeolite encapsulated catalysts on dispersion and activity for Pt-based catalysts.In addition,we highlight the use of machine learning to predict catalyst performance and guide the development of nextgeneration Pt-based catalyst materials.This review synthesizes insights from experimental studies and machine learning computational modeling and aims to provide a route for overcoming the limitations of Pt-based catalysts and advancing the PDH process.展开更多
Crystalized CeO_(2)structures were typically considered potential photocatalysts due to their great capacity to alter the active sites’size and ability to absorb light.However,the controllable fabrication of well-def...Crystalized CeO_(2)structures were typically considered potential photocatalysts due to their great capacity to alter the active sites’size and ability to absorb light.However,the controllable fabrication of well-defined hierarchical structures of CeO_(2)with high reactive facets is significant and challenging.Herein,a series of CeO_(2)supports including hierarchical flower-like(F-CeO_(2)),ball-like(B-CeO_(2)),cube-like(C-CeO_(2)),and rod-like CeO_(2)(R-CeO_(2))supports were prepared by hydrothermal method(BCeO_(2),R-CeO_(2)and C-CeO_(2))or ice-bath method(F-CeO_(2))respectively.V atoms were selected as the active atoms and loaded on these supports.Their structure-activity relationship in photo-assisted thermal propane dehydrogenation(PTPDH)was investigated systematically.The samples were characterized by Xray diffraction,scanning electron microscopy,transmission electron microscopy,N2 adsorption-desorption isotherms,and Fourier transform infrared spectrum.Results show that R-CeO_(2)support exhibits the biggest surface area thus achieving the best dispersion of VOx species.UV-vis spectrum and photoluminescence spectrum indicate that V/F-CeO_(2)has the best light adsorption property and V/R-CeO_(2)has the best carrier migration capacity.The activity tests demonstrate that the V/R-CeO_(2)has the largest net growth rate and the V/F-CeO_(2)has the biggest relative growth ratio.Furthermore,the non-thermal effect was confirmed by the kinetic method,which lowers the propane reaction orders,selectively promoting the first C-H bond activation.The light radiation TPSR experiment confirmed this point.DFT calculations show a good linear relationship between the energy barrier and the exchanged electron number.It inspires the design of high-reactive facets for boosting the intrinsic activity of the C-H bond in photoassisted thermal chemical processes.展开更多
Metal oxide catalysts are widely employed in propane dehydrogenation(PDH)for propylene synthesis,requiring sequential reduction-reaction-regeneration cycles.However,the eff ect of water present in the inlet gas or rea...Metal oxide catalysts are widely employed in propane dehydrogenation(PDH)for propylene synthesis,requiring sequential reduction-reaction-regeneration cycles.However,the eff ect of water present in the inlet gas or reactor on the catalytic per-formance of various metal oxides remains insuffi ciently understood.This study examines the infl uence of water on supported metal oxide catalysts,specifi cally CoO x/Al_(2)O_(3),VO x/Al_(2)O_(3),and an industrial analog CrO x/Al_(2)O_(3) catalyst.By combining titration experiments,in situ Fourier transform infrared spectroscopy,kinetic analysis,and isotopic techniques,we demon-strate that even trace amounts of water can markedly suppress PDH performance via dissociative adsorption on the oxide surface.Methanol pretreatment eff ectively scavenges adsorbed water,recovering Lewis acid-base sites and consequently restoring PDH activity.This work underscores the profound inhibitory role of trace water in PDH over metal oxide catalysts and illustrates the potential of methanol pretreatment as an effective strategy to mitigate this limitation.展开更多
As an important chemical product,propylene(C_(3)H_(6))is widely used in production of many crucial chemical products such as polypropylene.Propane(C_(3)H_(8))is introduced as an inevitable gas impurity during the naph...As an important chemical product,propylene(C_(3)H_(6))is widely used in production of many crucial chemical products such as polypropylene.Propane(C_(3)H_(8))is introduced as an inevitable gas impurity during the naphtha cracking in propylene production.At present,thermal-driven energy-intensive cryogenic distillation is the most common purification method in industry.An energy-efficient,cost-effective and environmental-friendly separation technology is required to get polymer grade C_(3)H_(6)(higher than 99.5%).In face of the increasing demand of propylene,new separation technology based on porous adsorbents is expected to be a promising alternative.In recent years,metal-organic frameworks(MOFs)have obtained attention by their high porosity,regular adjustable pore shape and pore environment and keep making breakthroughs in separation and purification of many industrial gas mixtures,and are thus considered as one of the most potential types of adsorbents.The physical properties of C_(3)H_(6)and C_(3)H_(8),such as boiling point,size and kinetic diameter,are close to each other,making their separation a challenge.Most C_(3)H_(6)/C_(3)H_(8)sieving MOFs based on narrow sieving channels that restrict the access of molecules larger than their confined entrance purify mixtures at the cost of diffusion and capacity.To improve the adsorption of MOFs based on molecular sieving,a novel‘pearl-necklace’strategy was designed,which was named for its connected channel and molecular pocket vividly,but the diffusion limitation remains unsolved.展开更多
Directional design of efficient catalysts for volatile organic compounds degradation remains a complex,yet effective and challenging process.Herein,oxygen-rich vacancy Co_(3)O_(4)-anchored Pt catalysts were prepared t...Directional design of efficient catalysts for volatile organic compounds degradation remains a complex,yet effective and challenging process.Herein,oxygen-rich vacancy Co_(3)O_(4)-anchored Pt catalysts were prepared through atom-trapping strategy and relevant vacancy defect inductive effect was proposed.The 0.6Pt/VO-Co_(3)O_(4)catalyst presented a reaction rate value of 32.2×10^(-5)mol·g_(cat)^(-1)·s^(-1)at 160℃for catalytic propane total oxidation,which was nearly 5 times the reaction rate of Co_(3)O_(4)(6.7×10^(-5)mol·g_(cat)^(-1)·s^(-1)).Also,it exhibited excellent water-resistance and catalytic stability.The Pt atoms were stabilized on the Co_(3)O_(4)surface by vacancy defects to improve dispersion.Meanwhile,the vacancy defect inductive effect induced stronger electron interaction between Pt and Co_(3)O_(4)on the surface,thus promote the redox ability at low-temperature.The mobility and oxygen-activating ability of surface lattice oxygen were also strengthened by the vacancy defect inductive effect.This facilitated the generation of more surface-active oxygen species for the cleavage of C-H bond and the deep oxidation of intermediate species.Overall,this study proposed a novel concept the fabrication of highly efficient catalysts for the purpose of catalytic oxidation.展开更多
基金sponsored by the Department of Defense,Defense Threat Reduction Agency under the Materials Science in Extreme Environments University Research Alliance,HDTRA1-20-2-0001。
文摘Chemical warfare agents(CWAs)remain a persistent hazard in many parts of the world,necessitating a deeper exploration of their chemical and physical characteristics and reactions under diverse conditions.Diisopropyl methylphosphonate(DIMP),a commonly used CWA surrogate,is widely studied to enhance our understanding of CWA behavior.The prevailing thermal decomposition model for DIMP,developed approximately 25 years ago,is based on data collected in nitrogen atmospheres at temperatures ranging from 700 K to 800 K.Despite its limitations,this model continues to serve as a foundation for research across various thermal and reactive environments,including combustion studies.Our recent experiments have extended the scope of decomposition analysis by examining DIMP in both nitrogen and zero air across a lower temperature range of 175??C to 250??C.Infrared spectroscopy results under nitrogen align well with the established model;however,we observed that catalytic effects,stemming from decomposition byproducts and interactions with stainless steel surfaces,alter the reaction kinetics.In zero air environments,we observed a novel infrared absorption band.Spectral fitting suggests this band may represent a combination of propanal and acetone,while GCMS analysis points to vinyl formate and acetone as possible constituents.Although the precise identity of these new products remains unresolved,our findings clearly indicate that the existing decomposition model cannot be reliably extended to lower temperatures or non-nitrogen environments without further revisions.
基金This project was supported by the National Natural Science Foundation of China.
文摘Both direct and sensitized irradiations of the endo title compound lead to a decarbony- lation product,4-isopropylbiphenyl,via Norrish Type 1 reaction,while the exo isomer gives a carbene intermediate and subsequently formaldehyde 2-biphenylyl isopropyl hemiacetal,which in turn gradually decomposes to dimethyl phenylbenzyl alcohol at room temperature.The triplet pathway dominates the photoreaction of the exo isomer.The singlet and triplet lifetimes of the reactant are found to be 0.29 ns and 5.4μs,respectively.~3(n,π~*),~1(n,π~*),~3(π,π~*)electronic configurations of the exo isomer and ~3(π,π~*)of the endo isomer are photochemically active,but ~1(π,π~*)of the endo isomer shows indirect photoreactivity.
基金financially supported by the National Natural Science Foundation of China(Grant No.42102202)U.S.Department of Energy Geosciences program(DE-SC0016271)。
文摘Hydrocarbons are one of the important fluids within the Earth's crust,and different biotic and abitoic processes can generate hydrocarbon during geological periods.Tracing the sources and sinks of hydrocarbons can help us better understand the carbon cycle of the earth.In this study,an improved approach of adsorbed hydrocarbons extraction from sediments was established.The improved thermal desorption approach,compound-specific isotope analysis and position-specific isotope analysis were integrated to investigate the molecular and intramolecular isotope fractionation between trace hydrocarbon gases within sediments and geological hydrocarbon deposits.The isotopic compositions of the terminal position carbon of propane(δ^(13)C_(terminal))serves as a correlation indicator between trace hydrocarbon gases within sediments and geological hydrocarbon deposits.The tight sandstone gas from the Turpan-Hami Basin is a first case study for the application of this novel method to trace hydrocarbon origins.The results showed that the hydrocarbons in the tight sandstone gases in the study area most likely originated from humic organic matter(typeⅢkerogen)at an early mature stage.δ^(13)C_(terminal)values of the thermally desorbed propane gases from different source rocks were distinguishable and the values of the tight sandstone gases significantly overlap with those of the Lower Jurassic Sangonghe source rocks,suggesting their genetic relationship.Overall,the results provided novel position-specific carbon isotopic constraints on origins of hydrocarbons.
文摘We report a robust pillar-layered metal-organic framework,Zn‑tfbdc‑dabco(tfbdc:tetrafluoroterephthal-ate,dabco:1,4-diazabicyclo[2.2.2]octane),featuring the fluorinated pore environment,for the preferential binding of propane over propylene and thus highly inverse selective separation of propane/propylene mixture.The inverse propane-selective performance of Zn‑tfbdc‑dabco for the propane/propylene separation was validated by single-component gas adsorption isotherms,isosteric enthalpy of adsorption calculations,ideal adsorbed solution theory calculations,along with the breakthrough experiment.The customized fluorinated networks served as a propane-trap to form more interactions with the exposed hydrogen atoms of propane,as unveiled by the simulation studies at the molecular level.With the advantage of inverse propane-selective adsorption behavior,high adsorption capacity,good cycling stability,and low isosteric enthalpy of adsorption,Zn‑tfbdc‑dabco can be a promising candidate adsorbent for the challenging propane/propylene separation to realize one-step purification of the target propylene substance.
文摘Propylene,a pivotal chemical feedstock,is extensively used in synthesizing high-value derivatives such as polypropylene and acrylonitrile[1].Although propylene is predominantly produced via naphtha cracking,a persistent supply-demand gap exists[2].Non-oil routes,such as propane dehydrogenation(PDH),are increasingly attractive,particularly with the availability of shale gas[3].Modern non-oxidative PDH heavily relies on Pt nanoparticle catalysts promoted with SnOx(e.g.,PtSn/Al2O3 used in Honeywell UOP's Oleflex process)[4].However,these systems suffer from inherent limitations:high Pt costs,coke formation via deep dehydrogenation,and sintering during regeneration-necessitating environmentally detrimental oxychlorination treatments to restore activity[5].
文摘Non-oxidative dehydrogenation of propane(PDH)is an important route for large-scale on purpose propene production.Although cobalt-based catalysts are promising alternatives to currently used platinum-or chromium oxide-based catalysts,their further developments are hindered by the uncertainties related to the kind of the active sites involved in the desired and side reactions.To contribute to closing such a gap,we systematically investigate the role of oxidized CoO_(x) and metallic Co0 species in the PDH reaction over catalysts based in Silicalite-1 with supported CoO_(x) species differing in their redox properties.C_(3)H_(8) pulse experiments with sub-millisecond and second resolution at pulse sizes of about 13 and 2200 nmol,respectively,combined with in-depth catalyst characterization and PDH tests at different propane conversions enabled us to understand how the reaction-induced reduction of CoO_(x) affects product selectivity.Propane readily reacts with CoO_(x) to yield propene,carbon oxides and water.The formed Co0 species show high activity to coking and cracking reactions.However,if the size of such species is below 2 nm,these undesired reactions are significantly hindered due to the coverage of the active sites by carbon-containing species.The remaining uncovered surface Co0 sites selectively dehydrogenate propane to propene.The best-performing catalyst showed higher activity than a commercial-like K-CrOx/Al_(2)O_(3) and operated durable in a series of 10 dehydrogenation/regeneration cycles under industrial relevant conditions.The space time yield of propene formation of 0.97 kg·h^(-1)·kgcat^(-1) was achieved at 550℃,52%equilibrium propane conversion and 95% propene selectivity.
文摘Recent studies have revealed the extraordinary performance of zirconium oxide in propane dehydrogenation,which is attributed to the excellent reactivity of the coordinatively unsaturated zirconium sites(Zr_(cus))around the oxygen vacancies.The origin of the enhanced catalytic activity of ZrO_(2)with defective tetrahedral Zr sites was examined by direct comparison with its pristine counterpart in the current study.Electronic-structure analysis revealed that electrons from oxygen removal were localized within vacancies on the defective surface,which directly attacked the C-H bond in propane.The involvement of localized electrons activates the C-H bond via back-donation to the antibonding orbital on the defective surface;conversely,charge is transferred from propane to the pristine surfaces.The barrier for the first C-H bond activation is clearly significantly reduced on the defective surfaces compared to that on the pristine surfaces,which verifies the superior activity of Zr_(cus).Notably,however,the desorption of both propene and hydrogen molecules from Zr_(cus)is more difficult due to strong binding.The calculated turnover frequency(TOF)for propene formation demonstrates that the pristine surfaces exhibit better catalytic performance at lower temperatures,whereas the defective surfaces have a larger TOF at high temperatures.However,the rate-determining step and reaction order on the defective surface differ from those on the pristine surface,which corroborates that the catalysts follow different mechanisms.A further optimization strategy was proposed to address the remaining bottlenecks in propane dehydrogenation on zirconium oxide.
文摘Propane dehydrogenation(PDH)has emerged as a key on-purpose technology for the production of propylene,but it often depends on toxic chromium and expensive platinum catalysts,highlighting the need for environmentally friendly and cost-effective alternatives.In this study,we developed a facile impregnation method to fabricate unsaturated Co single-atoms with a tricoordinated Co_(1)O_(3)H_(x) structure by regulating silanol nests in purely siliceous Beta zeolites.Detailed PDH catalytic tests and characterizations revealed a positive correlation between the presence of silanol nests and enhanced catalytic activity.Additionally,the unsaturated Co single-atoms exhibited a carbon deposition rate more than an order of magnitude slower than that of Co nanoparticles.Notably,the optimized Co_(0.3%)/deAl-meso-Beta catalyst achieved a record-high propylene formation rate of 21.2 mmol_(C3H6) g_(cat)^(-1) h^(-1),with an exceptional propylene selectivity of 99.1%at 550℃.Moreover,the Co_(0.3%)/deAl-meso-Beta catalyst demonstrated excellent stability,with negligible deactivation after 5 consecutive regeneration cycles.This study emphasizes the pivotal role of silanol nests of zeolites in stabilizing and modulating the coordination environment of metallic active sites,providing valuable insights for the design of high-activity,high-stability,and low-cost PDH catalysts.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1506000)Gusu Innovation and Entrepreneurship Leading Talents Program(ZXL2022497)+5 种基金Jiangsu Distinguished Professor programfinancial support by National Natural Science Foundation of China(Grant No.22301057)Natural Science Foundation of Hebei Province(Grant No.B2023201065)Science Research Project of Hebei Education Department(Grant No.BJK2024103)supported by the Open Research Fund of Shanghai Key Laboratory of High-resolution Electron MicroscopyOpen Project of State Key Laboratory of Supramolecular Structure and Materials(sklssm2024019),ShanghaiTech University。
文摘The dehydrogenation of alkanes has emerged as a vital complementary process to address the increasing global demand for olefins.A key challenge remains in the construction of novel active centers that offer superior activity,stability,and cost-effectiveness.Herein,tricoordinated cobalt atoms were successfully fabricated through an in-situ ligand-protected synthesis by introducing tungsten atoms into zeolite frameworks.These unsaturated Co species efficiently activate C-H bonds while suppressing C-C bond cleavage,resulting in exceptional catalytic activity and olefin selectivity in both propane and ethane dehydrogenation reactions.The optimized Co_(0.2%)@0.01W-S-1 catalyst demonstrated an impressive propylene formation rate of 15.2 molC_(3H6)gcC h^(-1)at 823 K and an ethylene formation rate of 240.3mol_(C2H4)g_(Co)^(-1)h^(-1)at 913 K,with propylene and ethylene selectivities of 99.0%and 97.5%,respectively.These results not only significantly surpass conventional tetracoordinated Co catalysts but also rival some Pt-based catalysts under similar conditions.Importantly,the catalyst exhibited excellent stability in dehydrogenation reactions,with no significant loss in catalytic activity after five consecutive regeneration cycles.This work offers valuable insights into the design of zeolite-supported non-precious metal catalysts with high activity and durability for efficient alkane dehydrogenation.
文摘Dispersing metals from nanoparticles to clusters is often achieved using ligand protection methods,which exhibit unique properties such as suppressing structure-sensitive side reactions.However,this method is limited by the use of different metal precursor salts corresponding to different ligands.An alternative approach,the ion exchange(IE)method,can overcome this limitation to some extent.Nevertheless,there is still an urgent need to address the stabilization of metals(especially precious metals)by using IE method.Here,we reported a Pt cluster catalyst prepared mainly by anchoring Pt atoms via O located near the framework Zn in zincosilicate zeolites and riveted by zeolite surface rings after reduction(reduced Pt/Zn-3-IE).The catalyst can achieve an initial propane conversion of 26%in a pure propane atmosphere at 550℃and shows little deactivation even after 7.5 d of operation.Moreover,the alteration of catalyst by the introduction of framework Zn was also highlighted and interpreted.
基金supported by the National Natural Science Foundation of China(Nos.22035009,22178381)the National Key R&D Program of China(Nos.2021YFA1501301,2021YFC2901100)the State Key Laboratory of Heavy Oil Processing(No.2021-03).
文摘Transition metal cobalt exhibits strong activation capabilities for alkanes,however,the instability of Co sites leads to sintering and coke deposition,resulting in rapid deactivation.Hierarchical zeolites,with their diverse pore structures and high surface areas,are used to effectively anchor metals and enhance coke tolerance.Herein,a post-treatment method using an alkaline solution was employed to synthesize meso-microporous zeolite supports,which were subsequently loaded with Co species for propane dehydrogenation catalyst.The results indicate that the application of NaOH,an inorganic base,produces supports with a larger mesopore volume and more abundant hydroxyl nests compared to TPAOH,an organic base.UV-vis,Raman,and XPS analyses reveal that Co in the 0.5Co/SN-1-0.05 catalyst is mainly in the form of tetrahedral Co^(2+),which effectively activates C-H bonds.In contrast,the 0.5Co/S-1 catalyst contains mainly Co_(3)O_(4)species.Co^(2+)supported on hierarchical zeolites shows better propane conversion(58.6%)and propylene selectivity(>96%)compared to pure silica zeolites.Coke characterization indicates that hierarchical zeolites accumulate more coke,but it is mostly in the form of easily removable disordered carbon.The mesopores in the microporous zeolite support help disperse the active Co metal and facilitate coke removal during dehydrogenation,effectively preventing deactivation from sintering and coke coverage.
基金supported by the National Key Research and Development Project of China(No.2022YFE0113800)the National Natural Science Foundation of China(No.22102013)+2 种基金Natural Science Foundation of Chongqing(No.cstc2021jcyj-msxmX0945)Venture and Innovation Support Program for Chongqing Overseas Returnees(No.cx2020107)Thousand Talents Program for Distinguished Young Scholars,Postdoctoral Fellowship Program of CPSF(No.GZB20230910)。
文摘Propane dehydrogenation(PDH)is a vital industrial process for producing propene,utilizing primarily Cr-based or Pt-based catalysts.These catalysts often suffer from challenges such as the toxicity of Cr,the high costs of noble metals like Pt,and deactivation issues due to sintering or coke formation at elevated temperatures.We introduce an exceptional Ru-based catalyst,Ru nanoparticles anchored on a nitrogendoped carbon matrix(Ru@NC),which achieves a propane conversion rate of 32.2%and a propene selectivity of 93.1%at 550°C,with minimal coke deposition and a low deactivation rate of 0.0065 h^(-1).Characterizations using techniques like TEM and XPS,along with carefully-designed controlled experiments,reveal that the notable performance of Ru@NC stems from the modified electronic state of Ru by nitrogen dopant and the microporous nature of the matrix,positioning it as a top contender among state-of-the-art PDH catalysts.
文摘Direct converting carbon dioxide(CO_(2))and propane(C_(3)H_(8))into aromatics with high carbon utilization offers a desirable opportunity to simultaneously mitigate CO_(2)emission and adequately utilize C_(3)H_(8) in shale gas.Owing to their thermodynamic resistance,converting CO_(2)and C_(3)H_(8) respectively remains difficult.Here,we achieve 60.2%aromatics selectivity and 48.8%propane conversion over H-ZSM-5-25 via a zeolite-catalyzing the coupling of CO_(2)and C_(3)H_(8).Operando dual-beam FTIR spectroscopy combined with ^(13)C-labeled CO_(2)tracing experiments revealed that CO_(2)is directly involved in the generation of aromatics,with its carbon atoms selectively embedded into the aromatic ring,bypassing the reverse water-gas shift pathway.Accordingly,a cooperative aromatization mechanism is proposed.Thereinto,lactones,produced from CO_(2)and olefins,are proven to be the key intermediate.This work not only provides an opportunity for simultaneous conversion of CO_(2)and C_(3)H_(8),but also expends coupling strategy designing of CO_(2)and alkanes over acidic zeolites.
基金supported by the National Key Research and Development Program of China(2022YFE0208300)the Natural Science Foundation of China(22078354)。
文摘The oxidative dehydrogenation of propane to propylene using CO_(2)(CO_(2)-ODH)offers a promising route for both propylene production and CO_(2)utilization.In this study,we investigate the effect of alkali metal doping on Pt-based catalysts in CO_(2)-ODH reactions.The optimized 0.1 KPt/S-1 catalyst achieved a high propane conversion of 48.3%,propylene selectivity of 85.5%,and CO_(2)conversion of 19.1%at a low temperature of 500℃with the Pt loading of 0.2 wt%and K loading of 0.1 wt%respectively.Characterization techniques,including high-resolution transmission electron microscope(HR-TEM),CO-diffuse reflectance infrared Fourier transform spectroscopy(CO-DRIFTS),X-ray absorption fine structure(XAFS),and X-ray Photoelectron Spectroscopy(XPS),revealed that the doping of K with Pt led to a strong interaction between potassium and platinum(Pt-KO_(x)cluster).This interaction resulted in a reduction of Pt particle size and a local enrichment of electron density around Pt atoms.These structural modifications improved the anchoring of Pt nanoparticles and enhanced Pt atom dispersion,thereby enhancing the activity of the catalyst and minimizing side reactions.Additionally,pyridine infrared(Py-IR)and temperature-programmed desorption(TPD)studies demonstrated that the prepared0.1 KPt/S-1 catalyst exhibited optimal acidity,which promoted C–H activation and facilitated the efficient adsorption and activation of CO_(2).These dual effects significantly lowered the activation energy for CO_(2)-ODH,enabling efficient dehydrogenation to propylene at a lower temperature of 500℃.This work highlights the critical role of alkali metal doping in modifying the electronic properties of Pt and optimizing catalyst acidity,which collectively contribute to the enhanced performance of the 0.1 KPt/S-1 catalyst.These findings offer valuable insights into the mechanistic pathway of CO_(2)-ODH and provide a foundation for the rational design of high-performance dehydrogenation catalysts.
基金support from Liaoning Revitalization Talents Program(XLYC2203068)National Natural Science Foundation of China(21902116)2024 Fundamental Research Funding of the Educational Department of Liaoning Province.Y.L.acknowledges the Program of China Scholarships Council(No.202206250016).
文摘Direct propane dehydrogenation(DPDH)represents a highly attractive route for on-purpose propylene production,a key building block in the petrochemical industry.In particular,among various catalytic platforms,vanadium-based catalysts have emerged as promising candidates due to their tunable properties including redox ability,surface acidity,and resistance to coking.Although the catalytic community has obtained great achievement in this area,how to promote vanadium-based catalysts towards the next step in DPDH applications like industrial-level implementations is still challenging.Moreover,there are still several controversial theories in our community,meaning it is necessary to clarify these indistinct points to pave the way for the next generation of research.Herein,the pivotal modification strategies of vanadium-based catalysts have been summarized via introducing representative works.In addition,the current unclear mechanism and research gaps,especially in the issues of deactivation and selectivity control,are also revealed so that the potential research directions are well-founded proposed.By integrating fundamental understanding and practical considerations,this review aims to inspire the further development of vanadium-based DPDH catalysts for in-depth academic research and next-generation industrial deployment.
文摘Propane dehydrogenation(PDH)is a key process for increasing the production of propylene,which is an important part of the chemical industry.Platinum-based catalysts have emerged as efficient catalysts for this reaction due to their excellent activity and selectivity.However,challenges such as high platinum cost,catalyst deactivation,and side reactions remain significant barriers to their widespread use in industry.This review provides a comprehensive overview of recent advances in platinumbased catalysts for PDH,focusing on strategies to optimize their performance.We discuss the design and synthesis of Pt-based catalysts,emphasizing the role of promoters,such as Sn,Zn,Ga,and other promoters,in improving selectivity and stability.We also explore the effects of support materials and zeolite encapsulated catalysts on dispersion and activity for Pt-based catalysts.In addition,we highlight the use of machine learning to predict catalyst performance and guide the development of nextgeneration Pt-based catalyst materials.This review synthesizes insights from experimental studies and machine learning computational modeling and aims to provide a route for overcoming the limitations of Pt-based catalysts and advancing the PDH process.
基金the National Key R&D Program of China(Nos.2021YFA1501301,2021YFC2901100)the National Natural Science Foundation of China(Nos.22178381,22035009).
文摘Crystalized CeO_(2)structures were typically considered potential photocatalysts due to their great capacity to alter the active sites’size and ability to absorb light.However,the controllable fabrication of well-defined hierarchical structures of CeO_(2)with high reactive facets is significant and challenging.Herein,a series of CeO_(2)supports including hierarchical flower-like(F-CeO_(2)),ball-like(B-CeO_(2)),cube-like(C-CeO_(2)),and rod-like CeO_(2)(R-CeO_(2))supports were prepared by hydrothermal method(BCeO_(2),R-CeO_(2)and C-CeO_(2))or ice-bath method(F-CeO_(2))respectively.V atoms were selected as the active atoms and loaded on these supports.Their structure-activity relationship in photo-assisted thermal propane dehydrogenation(PTPDH)was investigated systematically.The samples were characterized by Xray diffraction,scanning electron microscopy,transmission electron microscopy,N2 adsorption-desorption isotherms,and Fourier transform infrared spectrum.Results show that R-CeO_(2)support exhibits the biggest surface area thus achieving the best dispersion of VOx species.UV-vis spectrum and photoluminescence spectrum indicate that V/F-CeO_(2)has the best light adsorption property and V/R-CeO_(2)has the best carrier migration capacity.The activity tests demonstrate that the V/R-CeO_(2)has the largest net growth rate and the V/F-CeO_(2)has the biggest relative growth ratio.Furthermore,the non-thermal effect was confirmed by the kinetic method,which lowers the propane reaction orders,selectively promoting the first C-H bond activation.The light radiation TPSR experiment confirmed this point.DFT calculations show a good linear relationship between the energy barrier and the exchanged electron number.It inspires the design of high-reactive facets for boosting the intrinsic activity of the C-H bond in photoassisted thermal chemical processes.
基金supported by the National Key R&D Program of China(No.2023YFA1507800)the National Science Foundation of China(Nos.22121004,22122808,22478279,and 22108201)+1 种基金the Haihe Laboratory of Sustainable Chemical Trans-formations,the Program of Introducing Talents of Discipline to Uni-versities(No.BP0618007)the XPLORER PRIZE.
文摘Metal oxide catalysts are widely employed in propane dehydrogenation(PDH)for propylene synthesis,requiring sequential reduction-reaction-regeneration cycles.However,the eff ect of water present in the inlet gas or reactor on the catalytic per-formance of various metal oxides remains insuffi ciently understood.This study examines the infl uence of water on supported metal oxide catalysts,specifi cally CoO x/Al_(2)O_(3),VO x/Al_(2)O_(3),and an industrial analog CrO x/Al_(2)O_(3) catalyst.By combining titration experiments,in situ Fourier transform infrared spectroscopy,kinetic analysis,and isotopic techniques,we demon-strate that even trace amounts of water can markedly suppress PDH performance via dissociative adsorption on the oxide surface.Methanol pretreatment eff ectively scavenges adsorbed water,recovering Lewis acid-base sites and consequently restoring PDH activity.This work underscores the profound inhibitory role of trace water in PDH over metal oxide catalysts and illustrates the potential of methanol pretreatment as an effective strategy to mitigate this limitation.
基金support of the National Natural Science Foundation of China(Nos.22378369 and 22205207)Major Project of Natural Science Foundation of Zhejiang Province(LD24B060001).
文摘As an important chemical product,propylene(C_(3)H_(6))is widely used in production of many crucial chemical products such as polypropylene.Propane(C_(3)H_(8))is introduced as an inevitable gas impurity during the naphtha cracking in propylene production.At present,thermal-driven energy-intensive cryogenic distillation is the most common purification method in industry.An energy-efficient,cost-effective and environmental-friendly separation technology is required to get polymer grade C_(3)H_(6)(higher than 99.5%).In face of the increasing demand of propylene,new separation technology based on porous adsorbents is expected to be a promising alternative.In recent years,metal-organic frameworks(MOFs)have obtained attention by their high porosity,regular adjustable pore shape and pore environment and keep making breakthroughs in separation and purification of many industrial gas mixtures,and are thus considered as one of the most potential types of adsorbents.The physical properties of C_(3)H_(6)and C_(3)H_(8),such as boiling point,size and kinetic diameter,are close to each other,making their separation a challenge.Most C_(3)H_(6)/C_(3)H_(8)sieving MOFs based on narrow sieving channels that restrict the access of molecules larger than their confined entrance purify mixtures at the cost of diffusion and capacity.To improve the adsorption of MOFs based on molecular sieving,a novel‘pearl-necklace’strategy was designed,which was named for its connected channel and molecular pocket vividly,but the diffusion limitation remains unsolved.
文摘Directional design of efficient catalysts for volatile organic compounds degradation remains a complex,yet effective and challenging process.Herein,oxygen-rich vacancy Co_(3)O_(4)-anchored Pt catalysts were prepared through atom-trapping strategy and relevant vacancy defect inductive effect was proposed.The 0.6Pt/VO-Co_(3)O_(4)catalyst presented a reaction rate value of 32.2×10^(-5)mol·g_(cat)^(-1)·s^(-1)at 160℃for catalytic propane total oxidation,which was nearly 5 times the reaction rate of Co_(3)O_(4)(6.7×10^(-5)mol·g_(cat)^(-1)·s^(-1)).Also,it exhibited excellent water-resistance and catalytic stability.The Pt atoms were stabilized on the Co_(3)O_(4)surface by vacancy defects to improve dispersion.Meanwhile,the vacancy defect inductive effect induced stronger electron interaction between Pt and Co_(3)O_(4)on the surface,thus promote the redox ability at low-temperature.The mobility and oxygen-activating ability of surface lattice oxygen were also strengthened by the vacancy defect inductive effect.This facilitated the generation of more surface-active oxygen species for the cleavage of C-H bond and the deep oxidation of intermediate species.Overall,this study proposed a novel concept the fabrication of highly efficient catalysts for the purpose of catalytic oxidation.
