Molybdenum carbide has shown great potential in various hydrogenation reactions,and serves as a primary active species for synthesis of ethanol from dimethyl oxalate hydrogenation process which is a crucial step in th...Molybdenum carbide has shown great potential in various hydrogenation reactions,and serves as a primary active species for synthesis of ethanol from dimethyl oxalate hydrogenation process which is a crucial step in the efficient utilization of coal resources.In this study,a molybdenum carbide catalyst with a three-dimensional mesh-like hollow structure and lattice defects was carefully designed.The MoO_(3)precursor with abundant oxygen vacancies and defects was prepared by flame spray pyrolysis,and a structural modifier,Cu,was introduced by sputtering.The Cu deposited by sputtering affected the carburization and phase evolution processes.A three-dimensional mesh-like hollow structure composed of defective molybdenum carbide is formed,with theβ-Mo_(2)C exhibiting lattice distortions and defects.This defectiveβ-Mo_(2)C exhibits high reactivity,and facilitates the C=O hydrogenation process,showing a high reactivity of 83.1%yield in the hydrogenation of dimethyl oxalate.This work provides a new approach to the design and application of molybdenum carbide catalysts.展开更多
The efficient catalytic conversion of fossil-based low-carbon small molecules to oxygen-containing chemicals is an attractive research topic in the fields of energy and chemical engineering.The selective oxidation of ...The efficient catalytic conversion of fossil-based low-carbon small molecules to oxygen-containing chemicals is an attractive research topic in the fields of energy and chemical engineering.The selective oxidation of dimethyl ether(DME),which is derived from fossil resources,represents a promising approach to producing high-concentration formaldehyde with low energy consumption.However,there is still a lack of catalysts achieving satisfactory conversion of DME with high selectivity for formaldehyde under mild conditions.In this work,an efficient iron-molybdate(FeMo)catalyst was developed for the selective oxidation of DME to formaldehyde.The DME conversion of 84% was achieved with a superior formaldehyde selectivity(77%)at 300℃,a performance that is superior to all previously reported results.In an approximately 550 h continuous reaction,the catalyst maintained a conversion of 64% and a formaldehyde selectivity of 79%.Combined X-ray diffraction(XRD),Transmission electron microscope(TEM),Ultraviolet-visible spectroscopy(UV-Vis),Hydrogen temperature-programmed reduction(H_(2)-TPR),Fourier transform infrared(FT-IR)analyses,along with density functional theory(DFT)calculations,demonstrated that the excellent FeMo catalyst was composed of active Fe_(2)(MoO_(4))_(3)and MoO_(3)phases,and there was an interaction between them,which contributed to the efficient DME dissociation and smooth hydrogen spillover,leading to a superior DME conversion.With the support of DME/O_(2)pulse experiments,in-situ Raman,in-situ Dimethyl ether infrared spectroscopy(DME-IR)and DFT calculation results,a Mars-van Krevelen(MvK)reaction mechanism was proposed:DME was dissociated on the interface between Fe_(2)(MoO_(4))_(3)and MoO_(3)phases to form active methoxy species firstly,and it dehydrogenated to give hydrogen species;the generated hydrogen species smoothly spilled over from Fe_(2)(MoO_(4))_(3)to MoO_(3)enhanced by the interaction between Fe_(2)(MoO_(4))_(3)and MoO_(3);then the hydrogen species was consumed by MoO_(3),leading to a reduction of MoO_(3),and finally,the reduced MoO_(3)was re-oxidized by O_(2),returning to the initial state.These findings offer valuable insights not only for the development of efficient FeMo catalysts but also for elucidating the reaction mechanism involved in the oxidation of DME to formaldehyde,contributing to the optimized utilization of DME derived from fossil resources.展开更多
Sperm cryopreservation is an essential technique for male fertility preservation,especially in men who are undergoing medical treatment.Conventional cryopreservation methods face limitations such as oxidative stress,D...Sperm cryopreservation is an essential technique for male fertility preservation,especially in men who are undergoing medical treatment.Conventional cryopreservation methods face limitations such as oxidative stress,DNA fragmentation,and cytotoxicity associated with traditional cryoprotectants like dimethyl sulfoxide(DMSO).Recent breakthroughs have focused on improving post-thaw sperm viability with novel cryoprotectants and innovative freezing strategies.Prospective approaches include the use of amino acid-based cryoprotectants,deep eutectic solvents,and antioxidants that have been described to prevent oxidative damage and maintain DNA integrity.Vitrification,a high-speed freezing technique that prevents ice crystal formation,has demonstrated superior outcomes compared to conventional slow freezing.Moreover,the Direct Dropping Method,a cryoprotectant-free approach,has been introduced as a contamination-minimizing technique that preserves sperm functionality.Multiomics tools are also utilized to determine biomarkers for protocol optimization.Despite these advancements,cryoprotectant toxicity is a central challenge,emphasizing the necessity for safer agents.Future research must focus on long-term sperm functionality and individualized cryopreservation strategies to maximize reproductive outcomes.The current review highlights the challenges associated with sperm cryopreservation,explores innovative strategies and novel cryoprotectants,underscores the significance of maintaining DNA integrity,and proposes future research directions to improve fertility preservation outcomes.展开更多
The catalytic direct synthesis of dimethyl carbonate(DMC)from CO_(2)and methanol is a crucial approach to utilizing CO_(2)and producing high-value chemicals.However,the high stability of the CO_(2)molecule imposes the...The catalytic direct synthesis of dimethyl carbonate(DMC)from CO_(2)and methanol is a crucial approach to utilizing CO_(2)and producing high-value chemicals.However,the high stability of the CO_(2)molecule imposes thermodynamic limitations on this reaction pathway,along with challenges related to insufficient catalyst activity and stability.Currently,solutions primarily focus on developing efficient catalyst.Herein,La-doped CeO_(2)nanoflower catalysts(La_(x)CeO_(2))were synthesized via hydrothermal method.Characterization reveals that La doping optimizes the pore structure and enriched oxygen vacancies,thereby enhancing catalytic performance.Notably,La_(0.1)CeO_(2)exhibits the largest pore size and highest oxygen vacancy content,achieving a remarkable DMC productivity of 9.42 mmol/g under 140℃,4 MPa of CO_(2),and 3 h of reactio n,surpassing pure CeO_(2)nano flowers.Based on experimental findings and in-situ diffuse infrared Fourier transform analysis,a plausible reaction pathway was proposed.This work underscores the potential of La_(x)CeO_(2)nano flowers as efficient catalysts for sustainable CO_(2)conversion to DMC.展开更多
Periodontitis is a common oral disease characterized by progressive alveolar bone resorption and inflammation of the periodontal tissues.Dimethyl fumarate(DMF)has been used in the treatment of various immune-inflammat...Periodontitis is a common oral disease characterized by progressive alveolar bone resorption and inflammation of the periodontal tissues.Dimethyl fumarate(DMF)has been used in the treatment of various immune-inflammatory diseases due to its excellent anti-inflammatory and antioxidant functions.Here,we investigated for the first time the therapeutic effect of DMF on periodontitis.In vivo studies showed that DMF significantly inhibited periodontal destruction,enhanced mitophagy,and decreased the M1/M2 macrophage ratio.In vitro studies showed that DMF inhibited macrophage polarization toward M1 macrophages and promoted polarization toward M2 macrophages,with improved mitochondrial function,inhibited oxidative stress,and increased mitophagy in RAW 264.7 cells.Furthermore,DMF increased intracellular mitochondrial Tu translation elongation factor(TUFM)levels to maintain mitochondrial homeostasis,promoted mitophagy,and modulated macrophage polarization,whereas TUFM knockdown decreased the protective effect of DMF.Finally,mechanistic studies showed that DMF increased intracellular TUFM levels by protecting TUFM from degradation via the ubiquitin-proteasomal degradation pathway.Our results demonstrate for the first time that DMF protects mitochondrial function and inhibits oxidative stress through TUFM-mediated mitophagy in macrophages,resulting in a shift in the balance of macrophage polarization,thereby attenuating periodontitis.Importantly,this study provides new insights into the prevention of periodontitis.展开更多
Ethanol synthesis via dimethyl oxalate hydrogenation has garnered increasing attention in the fields of syngas utilization.Althoughε-Fe_(2)C has been identified as a promising active species for DMO hydrogenation to ...Ethanol synthesis via dimethyl oxalate hydrogenation has garnered increasing attention in the fields of syngas utilization.Althoughε-Fe_(2)C has been identified as a promising active species for DMO hydrogenation to ethanol,its formation is kinetically challenging during carbonization.In this work,a Fe_(4)N phase was first synthesized by pretreating a 30Fe/SiO_(2)catalyst in an ammonia environment,followed by carbonization in a methanol-H_(2) flow to obtain ε-Fe_(2)C as the active phase.Fe_(4)N,rather than Fe-O-Si,facilitates the transformation into iron carbide during the carbonization process.The transformation pathway of iron nitride(Fe_(x)N)is mediated by intermediate iron carbonyl species(Fe-CO),ultimately leading to the formation of iron carbide as the active phase.The resulting catalyst exhibited 40 times higher catalytic activity than the untreated catalyst in DMO hydrogenation.Combined structure properties and DFT calculation revealed that the lower energy barrier ofε-Fe_(2)C for ester hydrogenation underpins/strengthens its superior performance,while the STY of ε-Fe_(2)C is 2.8 times that ofε'-Fe_(2.2)C and 58 times that ofχ-Fe_(5)C_(2).This study provides a novel strategy for designing highly efficient iron carbide catalysts for the esters hydrogenation system.展开更多
The direct conversion of greenhouse gas CO_(2) and low-cost CH3OH into valuable dimethyl carbonate(DMC)offers a promising low-carbon synthetic pathway,but the slow CO_(2) activation kinetics and entropy-decreasing nat...The direct conversion of greenhouse gas CO_(2) and low-cost CH3OH into valuable dimethyl carbonate(DMC)offers a promising low-carbon synthetic pathway,but the slow CO_(2) activation kinetics and entropy-decreasing nature of this reaction significantly restrict DMC yield to below 1%.In this work,2-cyanopyridine(2-CP)was employed as a dehydrating agent to suppress the reverse reaction between DMC and H_(2)O,shifting the thermodynamic equilibrium in favor of DMC production.Under this thermodynamic unconstrained condition,increasing oxygen vacancies,especially in the form of oxygen vacancy clusters,promotes catalytic activity significantly.We achieve a catalytic activity of 211 mmol/(g·h)at 140℃ on H_(2)-treated,oxygen-vacancy-clusters-rich CeO_(2) in the presence of 2-CP,a 1.6-fold increase compared to the activity with air-treated CeO_(2) under identical conditions.The DMC yield reaches 8.54%in a 20mL CH3OH solution with 2-CP,surpassing the calculated DMC yield of about 0.66%from the reaction equilibrium constant under the same conditions and without using the dehydrating agent.This work suggests the importance of using a dehydrating agent and also highlights oxygen vacancy clusters as pivotal active sites to promote DMC synthesis.Achieving sustainable DMC synthesis requires further exploration,encompassing strategies such as methods for regeneration of 2-CP.展开更多
A biodegradable and green organic compound octadecyl dimethyl benzyl amm-onium chloride(ODBAC)was used as an efficient inhibitor for cold rolled steel(CRS)in phosphoric acid(H_(3)PO_(4)).The mechanism of adsorption an...A biodegradable and green organic compound octadecyl dimethyl benzyl amm-onium chloride(ODBAC)was used as an efficient inhibitor for cold rolled steel(CRS)in phosphoric acid(H_(3)PO_(4)).The mechanism of adsorption and film formation of ODBAC on CRS was studied through experimental and theoretical calculations.The weight loss method shows that the inhibition efficiency of ODBAC can reach 92.01%at a concentration of 10 mg·L^(-1).The adsorption of ODBAC on the CRS surface conforms to the Langmuir isotherm model,which is a mixed adsorption mainly based on physical adsorption.The X-ray photoelectron spectroscopy(XPS)and contact angle results confirmed the existence of the ODBAC film and steel surface's hydrophobicity has been significantly enhanced.Electrochemical test results reveal that the film's formation mainly inhibits the cathodic corrosion reaction and effectively increases the charge transfer resistance.Quantum chemical calculations have found that N18 in ODBAC and C24 and C25 on the benzene ring are the key active adsorption sites.Molecular dynamics simulation results indicate that ODBAC can sharply reduce the free fraction volume to 8%and inhibit the diffusion of corrosion particles,meaning that the formed ODBAC film makes it difficult for corrosion particles to penetrate,thus improving the corrosion resistance of CRS in H_(3)PO_(4).展开更多
The hydrogenation of dimethyl oxalate(DMO)to ethanol(Et OH)represents a promising avenue for syngas conversion and plays a pivotal role in advancing sustainable energy economies.Nevertheless,designing catalysts with h...The hydrogenation of dimethyl oxalate(DMO)to ethanol(Et OH)represents a promising avenue for syngas conversion and plays a pivotal role in advancing sustainable energy economies.Nevertheless,designing catalysts with high Et OH yields at low temperatures remains a significant challenge.This study introduces an efficient catalyst featuring a rich SiO_(2)-Ni_(3)Mo_(3)N interface,which achieved a remarkable 97.5%Et OH yield at 210°C and 2 MPa.Impressively,an Et OH yield of 95%was also obtained at 210°C and 1.5 MPa.The research demonstrates that the addition of SiO_(2)fosters the development of a rich SiO_(2)-Ni_(3)Mo_(3)N interface,which enhances the concentration of Lewis acid sites(L-acid)and Brønsted acids sites(B-acid)within the catalyst.This enhancement promotes the adsorption of raw material and intermediate products while increasing H_(2)adsorption,thereby boosting the catalyst's deep hydrogenation capacity.Density functional theory(DFT)simulations indicate that SiO2incorporation modifies the catalyst's metal d-band center through electron transfer,increasing its adsorption capability for raw materials and intermediates and facilitating Et OH production.Consequently,this study achieves high Et OH yields at low temperatures,advances the industrialization process of syngas to Et OH conversion,and offers novel insights into constructing highly active catalytic interfaces for DMO hydrogenation.展开更多
Poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate)(PETG)possesses excellent properties and stability than traditional poly(ethylene terephthalate)(PET).However,the production and application of PETG are ...Poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate)(PETG)possesses excellent properties and stability than traditional poly(ethylene terephthalate)(PET).However,the production and application of PETG are restricted by the expensive monomer(1,4-cyclohexanedimethanol,CHDM).Direct upgrading of waste PET to dimethyl cyclohexane-1,4-dicarboxylate(DMCD)can promote the production of CHDM in large scale.In this work,a bifunctional Ru/UiO-66_(def)-SO_(3)H catalyst was synthesized and utilized in coupled methanolysis(of waste PET to dimethyl terephthalate(DMT))and hydrogenation(of DMT to DMCD)under mild condition.Characterizations revealed that Ru/UiO-66_(def)-SO_(3)H possessed mesopores(dominant channels of 2.72 and 3.44 nm),enlarged surface area(998 m^(2)·g^(–1)),enhanced acidity(580μmol·g^(–1)),and Ru nanoparticles(NPs)dispersed highly(45.1%)compared to those of Ru/UiO-66.These combined advantages could accelerate the methanolysis and hydrogenation reactions simultaneously,promoting the performance of direct upgrading of PET to DMCD in one pot.In particular,the conversion of PET and yield of DMCD over Ru/UiO-66_(def)-SO_(3)H reached 100%and 97.7%at 170℃and 3 MPa H_(2)within 6 h.Moreover,Ru/UiO-66_(def)-SO3H was also capable for the upcycling of waste PET-based products including beverage bottles,textile fiber and packaging film to DMCD.展开更多
Mordenite with different Si/Al ratios were synthesized by solvent-free method and used for dimethyl ether(DME)carbonylation reaction.The influence of Si/Al ratio in the feedstock on the structure,porosity and acid sit...Mordenite with different Si/Al ratios were synthesized by solvent-free method and used for dimethyl ether(DME)carbonylation reaction.The influence of Si/Al ratio in the feedstock on the structure,porosity and acid sites were systematically investigated.The characterization results showed that with the increase of Si/Al ratio in the feedstock,part of silicon species fail to enter the skeleton and the specific surface area and pore volume of the samples decreased.The amount of weak acid and medium strong acid decreased alongside with the increasing Si/Al ratio,and the amount of strong acid slightly increased.The Al atoms preferentially enter the strong acid sites in the 8 member ring(MR)channel during the crystallization process.The high Si/Al ratio sample had more acid sites located in the 8 MR channel,leading to more active sites for carbonylation reaction and higher catalytic performance.Appropriately increasing the Si/Al ratio was beneficial for the improvement of carbonylation reaction activity over the mordenite(MOR)catalyst.展开更多
Compared with organic electrolytes,aqueous electrolytes exhibit significantly higher ionic conductivity and possess inherent safety features,showcasing unique advantages in supercapacitors.However,challenges remain fo...Compared with organic electrolytes,aqueous electrolytes exhibit significantly higher ionic conductivity and possess inherent safety features,showcasing unique advantages in supercapacitors.However,challenges remain for low-salt aqueous electrolytes operating at high voltage and low temperature.Herein,we report a low-salt(0.87 m,m means mol kg^(-1))'salt in dimethyl sulfoxide/water'hybrid electrolyte with non-flammability via hybridizing aqueous electrolyte with an organic co-solvent of dimethyl sulfoxide(hydrogen bond acceptor).As a result,the 0.87 m hybrid electrolyte exhibits enhanced electrochemical stability,a freezing temperature below-50℃,and an outstanding ionic conductivity of 0.52mS cm~(-1)at-50℃.Dimethyl sulfoxide can anchor water molecules through intermolecular hydrogen bond interaction,effectively reinforcing the stability of water in the hybrid electrolyte.Furthermore,the interaction between dimethyl sulfoxide and water molecules diminishes the involvement of water in the generation of ordered ice crystals,finally facilitating the low-temperature performance of the hybrid electrolyte.When paired with the 0.87 m'salt in dimethyl sulfoxide/water'hybrid electrolyte,the symmetric supercapacitor presents a 2.0 V high operating voltage at 25℃,and can operate stably at-50℃.Importantly,the suppressed electrochemical reaction of water at-50℃further leads to the symmetric supercapacitor operated at a higher voltage of 2.6 V.This modification strategy opens an effective avenue to develop low-salt electrolytes for high-voltage and low-temperature aqueous supercapacitors.展开更多
It is well known that calcium oxide (CaO) has better catalytic efficiency than most heterogeneous catalysts in many transesterification reactions. However, the gradual deactivation problem prevents its large-scale app...It is well known that calcium oxide (CaO) has better catalytic efficiency than most heterogeneous catalysts in many transesterification reactions. However, the gradual deactivation problem prevents its large-scale application in industry. In this paper, the deactivation mechanism of CaO in a fixed-bed reactor is investigated based on the transesterification reaction of propylene carbonate and methanol. The leaching amount of CaO during the reaction was estimated by the concentration of Ca in the products. The pretreated and recovered catalysts were characterized by FT-IR, XRD, TG-MS and SEM-EDS. It is evident from experiments and characterization that the deactivation process of CaO is accompanied by the leaching of calcium species and the generation of CaCO3, which are also verified by DFT calculations. At high temperature and high weight hourly space velocity, the deactivation was attributed to the formation of dense CaCO3 shell, which prevents the contact between the feedstock and the active species inside.展开更多
Dimethyl carbonate(DMC)is a crucial chemical raw material widely used in organic synthesis,lithiumion battery electrolytes,and various other fields.The current primary industrial process employs a conventional sodium ...Dimethyl carbonate(DMC)is a crucial chemical raw material widely used in organic synthesis,lithiumion battery electrolytes,and various other fields.The current primary industrial process employs a conventional sodium methoxide basic catalyst to produce DMC through the transesterification reaction between vinyl carbonate and methanol.However,the utilization of this catalyst presents several challenges during the process,including equipment corrosion,the generation of solid waste,susceptibility to deactivation,and complexities in separation and recovery.To address these limitations,a series of alkaline poly(ionic liquid)s,i.e.[DVBPIL][PHO],[DVCPIL][PHO],and[TBVPIL][PHO],with different crosslinking degrees and structures,were synthesized through the construction of cross-linked polymeric monomers and functionalization.These poly(ionic liquid)s exhibit cross-linked structures and controllable cationic and anionic characteristics.Research was conducted to investigate the effect of the cross-linking degree and structure on the catalytic performance of transesterification in synthesizing DMC.It was discovered that the appropriate cross-linking degree and structure of the[DVCPIL][PHO]catalyst resulted in a DMC yield of up to 80.6%.Furthermore,this catalyst material exhibited good stability,maintaining its catalytic activity after repeated use five times without significant changes.The results of this study demonstrate the potential for using alkaline poly(ionic liquid)s as a highly efficient and sustainable alternative to traditional catalysts for the transesterification synthesis of DMC.展开更多
Background:Complementary medicine is an interesting field for extracting bio-active compounds from various plant and animal sources.The hepatoprotective effect of the methanolic extract of a species of sea cucumber ca...Background:Complementary medicine is an interesting field for extracting bio-active compounds from various plant and animal sources.The hepatoprotective effect of the methanolic extract of a species of sea cucumber called Holothuria leu-cospilota in an animal model of liver cancer caused by dimethyl nitrosamine(DMN)was studied.Methods:Wistar female rats were randomly divided into five groups(n=12):control(intact),positive control(received 1%DMN[10 mg/kg/week,intraperitoneally]for 12 weeks),and three treatment groups(received 50,100,and 200 mg/kg/day H.leu-cospilota extract orally for 12 weeks along with intraperitoneal administration of 1%DMN[10 mg/kg/week]).In all groups,ultrasound was performed on the liver every week to check its density.Blood sampling and liver isolation were performed on three occasions,at 4,8,and 12 weeks,to check liver enzymes and the histopathological condition of the liver tissue(every week,four animals from each group were randomly selected).Results:Liver density changes were evident from the eighth week onward in the positive control group.Histopathological results indicated pathologic changes in the positive control group after 4 weeks.The increase in liver enzymes in the posi-tive control group was significantly different from that in the treatment and control groups.Conclusions:We demonstrated the hepatoprotective effect of H.leucospilota on DMN-induced liver damage in rats using biochemical and histological parameters and ultrasonography.More additional research(in silico or in vitro)is needed to find the exact mechanism and the main biological compound in H.leucospilota.展开更多
The direct synthesis of dimethyl carbonate(DMC)from CO_(2)and methanol has attracted much attention as an environmentally benign and alternative route for conventional routes.Herein,a series of cerium oxide catalysts ...The direct synthesis of dimethyl carbonate(DMC)from CO_(2)and methanol has attracted much attention as an environmentally benign and alternative route for conventional routes.Herein,a series of cerium oxide catalysts with various textural features and surface properties were prepared by the one-pot synthesis method for the direct DMC synthesis from CO_(2)and methanol,and the structure-performance relationship was investigated in detail.Characterization results revealed that both of surface acid-base properties and the oxygen vacancies contents decreased with the rising crystallinity at increasingly higher calcination temperature accompanied by an unexpectedly volcano-shaped trend of DMC yield observed on the catalysts.In situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)studies indicated that the adsorption rate of methanol is slower than that of CO_(2)and the methanol activation state largely influences the formation of key intermediate.Although the enhanced surface acidity-basicity and oxygen vacancies brought by low-temperature calcination could facilitate the activation of CO_(2),the presence of excess strongly basic sites on low-crystallinity sample was detrimental to DMC synthesis due to the preferred formation of unreactive mono/polydentate carbonates as well as the further impediment of methanol activation.Moreover,with the use of 2-cyanopyridine as a dehydration reagent,the DMC synthesis was found to be both influenced by the promotion from the rapid in situ removal of water and the inhibition from the competitive adsorption of hydration products on the same active sites.展开更多
Product selectivity and reaction pathway are highly dependent on surface structure of heterogeneous catalysts.For vapor-phase hydrogenation of dimethyl oxalate(DMO),"EG route"(DMO→methyl glycolate(MG)ethyle...Product selectivity and reaction pathway are highly dependent on surface structure of heterogeneous catalysts.For vapor-phase hydrogenation of dimethyl oxalate(DMO),"EG route"(DMO→methyl glycolate(MG)ethylene glycol(EG)→ethanol(ET))and"MA route"(DMO→MG→methyl acetate(MA))were proposed over traditional Cu based catalysts and Mo-based or Fe-based catalysts,respectively.Herein,tunable yield of ET(93.7%)and MA(72.1%)were obtained through different reaction routes over WO_(x) modified Cu/SiO_(2) catalysts,and the corresponding reaction route was further proved by kinetic study and in-situ DRIFTS technology.Mechanistic studies demonstrated that H_(2) activation ability,acid density and Cu-WO_(x) interaction on the catalysts were tuned by regulating the surface W density,which resulted in the different reaction pathway and product selectivity.What's more,high yield of MA produced from DMO hydrogenation was firstly reported with the H_(2) pressure as low as 0.5 MPa.展开更多
The selective hydrogenation of dimethyl toluene-2,4-dicarbamate(TDC)to methyl cyclohexyl-2,4-dicarbamate(also called hydrogenated TDC,HTDC)is an essential process for non-phosgene synthesis of methylcyclohexane-2,4-di...The selective hydrogenation of dimethyl toluene-2,4-dicarbamate(TDC)to methyl cyclohexyl-2,4-dicarbamate(also called hydrogenated TDC,HTDC)is an essential process for non-phosgene synthesis of methylcyclohexane-2,4-diisocyanate.Herein,we prepared a series of supported Rh-based catalysts by the excessive impregnation method and investigated their catalytic performance for the selective hydrogenation of TDC.The emphasis was put on the influence of support properties on the catalytic performance.Among the prepared catalysts,Rh/g-Al_(2)O_(3)performed the best:a HTDC yield of 88.4%was achieved with a 100%conversion of TDC under the conditions of 100℃,3 MPa and 1 h.Furthermore,Rh/γ-Al_(2)O_(3)could be repetitively used for 4 times without a significant loss of its catalytic activity.TEM,XRD,N_(2)adsorption-desorption,H_(2)-TPR,NH_(3)/CO_(2)-TPD,XPS and ICP characterizations were employed to distinguish the properties of the prepared catalysts and the results were correlated with their catalytic performance.It is indicated that the yield of HTDC shows a positive relevance with the percentage of moderate-to-strong acid sites and the content of Rh^(n+)(n≥3)in the catalysts.High values of the percentage and the content can promote a strong interaction between Rh nanoparticles and the supports,facilitating both the transfer of electrons from Rh to the support and the formation of Rh^(n+)species.This is conducive to activating the benzene ring of TDC and thereby improving the yield of HTDC.展开更多
Dimethyl ether carbonylation to methyl acetate was comparatively investigated over mor- denite supported copper （Cu/HMOR） catalysts prepared by different methods including evaporation, urea hydrolysis, incipient wet...Dimethyl ether carbonylation to methyl acetate was comparatively investigated over mor- denite supported copper （Cu/HMOR） catalysts prepared by different methods including evaporation, urea hydrolysis, incipient wetness impregnation and ion-exchange. The results showed that Cu/HMOR prepared via iron-exchange method exhibited the highest catalytic activity due to the synergistic effect of active-site metal and acidic molecular sieve support. Conversion of 95.3% and methyl acetate selectivity of 94.9% were achieved under conditions of 210℃, 1.5 MPa, and GSHV of 4883 h-1. The catalysts were characterized by nitrogen absorption, X-ray diffraction, NH3 temperature program desorption, and CO temperature program desorption techniques. It was found that Cu/HMOR prepared by ion-exchange method possessed high surface area, moderate strong acid centers, and CO adsorption centers, which improved catalytic performance for the reaction of CO insertion to dimethyl ether.展开更多
The effect of calcination temperature on the catalytic activity for the dimethyl ether （DME） carbonylation into methyl acetate （MA） was investigated over mordenite supported copper （Cu/HMOR） prepared by ion-exch...The effect of calcination temperature on the catalytic activity for the dimethyl ether （DME） carbonylation into methyl acetate （MA） was investigated over mordenite supported copper （Cu/HMOR） prepared by ion-exchange process. The results showed that the catalytic activity was obviously affected by the calcination temperature. The maximal DME conversion of 97.2% and the MA selectivity of 97.9% were obtained over the Cu/HMOR calcined at 430 ℃ under conditions of 210 ℃, 1.5 MPa, and GSHV of 4883 h^-1. The obtained Cu/HMOR catalysts were characterized by powder X-ray diffraction, N2 absorption, NH3 temperature program desorption, CO temperature program desorption, and Raman techniques. Proper calcination temperature was effective to promote copper ions migration and diffusion, and led the support HMOR to possess more acid activity sites, which exhibited the complete decomposing of copper nitrate, large surface area and optimum micropore structure, more amount of CO adsorption site and proper amount of weak acid centers.展开更多
文摘Molybdenum carbide has shown great potential in various hydrogenation reactions,and serves as a primary active species for synthesis of ethanol from dimethyl oxalate hydrogenation process which is a crucial step in the efficient utilization of coal resources.In this study,a molybdenum carbide catalyst with a three-dimensional mesh-like hollow structure and lattice defects was carefully designed.The MoO_(3)precursor with abundant oxygen vacancies and defects was prepared by flame spray pyrolysis,and a structural modifier,Cu,was introduced by sputtering.The Cu deposited by sputtering affected the carburization and phase evolution processes.A three-dimensional mesh-like hollow structure composed of defective molybdenum carbide is formed,with theβ-Mo_(2)C exhibiting lattice distortions and defects.This defectiveβ-Mo_(2)C exhibits high reactivity,and facilitates the C=O hydrogenation process,showing a high reactivity of 83.1%yield in the hydrogenation of dimethyl oxalate.This work provides a new approach to the design and application of molybdenum carbide catalysts.
基金supported by the National Natural Science Foundation of China(U23A2088,22025206)the Dalian Innovation Support Plan for High Level Talents(2022RG13)+2 种基金DICP(Grant:DICP I202453,DICP I202234)the Fundamental Research Funds for the Central Universities(20720220008)support of the Liaoning Key Laboratory of Biomass Conversion for Energy and Material。
文摘The efficient catalytic conversion of fossil-based low-carbon small molecules to oxygen-containing chemicals is an attractive research topic in the fields of energy and chemical engineering.The selective oxidation of dimethyl ether(DME),which is derived from fossil resources,represents a promising approach to producing high-concentration formaldehyde with low energy consumption.However,there is still a lack of catalysts achieving satisfactory conversion of DME with high selectivity for formaldehyde under mild conditions.In this work,an efficient iron-molybdate(FeMo)catalyst was developed for the selective oxidation of DME to formaldehyde.The DME conversion of 84% was achieved with a superior formaldehyde selectivity(77%)at 300℃,a performance that is superior to all previously reported results.In an approximately 550 h continuous reaction,the catalyst maintained a conversion of 64% and a formaldehyde selectivity of 79%.Combined X-ray diffraction(XRD),Transmission electron microscope(TEM),Ultraviolet-visible spectroscopy(UV-Vis),Hydrogen temperature-programmed reduction(H_(2)-TPR),Fourier transform infrared(FT-IR)analyses,along with density functional theory(DFT)calculations,demonstrated that the excellent FeMo catalyst was composed of active Fe_(2)(MoO_(4))_(3)and MoO_(3)phases,and there was an interaction between them,which contributed to the efficient DME dissociation and smooth hydrogen spillover,leading to a superior DME conversion.With the support of DME/O_(2)pulse experiments,in-situ Raman,in-situ Dimethyl ether infrared spectroscopy(DME-IR)and DFT calculation results,a Mars-van Krevelen(MvK)reaction mechanism was proposed:DME was dissociated on the interface between Fe_(2)(MoO_(4))_(3)and MoO_(3)phases to form active methoxy species firstly,and it dehydrogenated to give hydrogen species;the generated hydrogen species smoothly spilled over from Fe_(2)(MoO_(4))_(3)to MoO_(3)enhanced by the interaction between Fe_(2)(MoO_(4))_(3)and MoO_(3);then the hydrogen species was consumed by MoO_(3),leading to a reduction of MoO_(3),and finally,the reduced MoO_(3)was re-oxidized by O_(2),returning to the initial state.These findings offer valuable insights not only for the development of efficient FeMo catalysts but also for elucidating the reaction mechanism involved in the oxidation of DME to formaldehyde,contributing to the optimized utilization of DME derived from fossil resources.
文摘Sperm cryopreservation is an essential technique for male fertility preservation,especially in men who are undergoing medical treatment.Conventional cryopreservation methods face limitations such as oxidative stress,DNA fragmentation,and cytotoxicity associated with traditional cryoprotectants like dimethyl sulfoxide(DMSO).Recent breakthroughs have focused on improving post-thaw sperm viability with novel cryoprotectants and innovative freezing strategies.Prospective approaches include the use of amino acid-based cryoprotectants,deep eutectic solvents,and antioxidants that have been described to prevent oxidative damage and maintain DNA integrity.Vitrification,a high-speed freezing technique that prevents ice crystal formation,has demonstrated superior outcomes compared to conventional slow freezing.Moreover,the Direct Dropping Method,a cryoprotectant-free approach,has been introduced as a contamination-minimizing technique that preserves sperm functionality.Multiomics tools are also utilized to determine biomarkers for protocol optimization.Despite these advancements,cryoprotectant toxicity is a central challenge,emphasizing the necessity for safer agents.Future research must focus on long-term sperm functionality and individualized cryopreservation strategies to maximize reproductive outcomes.The current review highlights the challenges associated with sperm cryopreservation,explores innovative strategies and novel cryoprotectants,underscores the significance of maintaining DNA integrity,and proposes future research directions to improve fertility preservation outcomes.
基金supported by Jiangsu Province Science and Technology Plan Special Fund(BZ2022053)National Natural Science Foundation of China(42476239)+1 种基金Natural Science Research Projects of Universities in Jiangsu Province(24KJD530004)the Dean/Opening Project of Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology(2021K008)。
文摘The catalytic direct synthesis of dimethyl carbonate(DMC)from CO_(2)and methanol is a crucial approach to utilizing CO_(2)and producing high-value chemicals.However,the high stability of the CO_(2)molecule imposes thermodynamic limitations on this reaction pathway,along with challenges related to insufficient catalyst activity and stability.Currently,solutions primarily focus on developing efficient catalyst.Herein,La-doped CeO_(2)nanoflower catalysts(La_(x)CeO_(2))were synthesized via hydrothermal method.Characterization reveals that La doping optimizes the pore structure and enriched oxygen vacancies,thereby enhancing catalytic performance.Notably,La_(0.1)CeO_(2)exhibits the largest pore size and highest oxygen vacancy content,achieving a remarkable DMC productivity of 9.42 mmol/g under 140℃,4 MPa of CO_(2),and 3 h of reactio n,surpassing pure CeO_(2)nano flowers.Based on experimental findings and in-situ diffuse infrared Fourier transform analysis,a plausible reaction pathway was proposed.This work underscores the potential of La_(x)CeO_(2)nano flowers as efficient catalysts for sustainable CO_(2)conversion to DMC.
基金Natural Science Foundation of China(grant nos.82270991)Zhejiang Provincial Natural Science Foundation of China/Outstanding Youth Science Foundation(grant no.LR21H140002)+4 种基金Medical Health Science and Technology Major Project of Zhejiang Provincial Health Commission(grant no.WKJ-ZJ-2311)Wenzhou Science and Technology Bureau Public Welfare Social Development(Medical and Health)Science and Technology Project(grant no.ZY2021015)Opening Research Fund from Shanghai Key Laboratory of Stomatology,Shanghai Ninth People’s Hospital,College of Stomatology,Shanghai Jiao Tong University School of Medicine(grant no.2022SKLS-KFKT011)Guangxi Key Laboratory of the Rehabilitation and Reconstruction for Oral and Maxillofacial Research(grant no.GXKLRROM2106)State Key Laboratory of Oral Diseases Open Fund(grant no.SKLOD2024OF08).
文摘Periodontitis is a common oral disease characterized by progressive alveolar bone resorption and inflammation of the periodontal tissues.Dimethyl fumarate(DMF)has been used in the treatment of various immune-inflammatory diseases due to its excellent anti-inflammatory and antioxidant functions.Here,we investigated for the first time the therapeutic effect of DMF on periodontitis.In vivo studies showed that DMF significantly inhibited periodontal destruction,enhanced mitophagy,and decreased the M1/M2 macrophage ratio.In vitro studies showed that DMF inhibited macrophage polarization toward M1 macrophages and promoted polarization toward M2 macrophages,with improved mitochondrial function,inhibited oxidative stress,and increased mitophagy in RAW 264.7 cells.Furthermore,DMF increased intracellular mitochondrial Tu translation elongation factor(TUFM)levels to maintain mitochondrial homeostasis,promoted mitophagy,and modulated macrophage polarization,whereas TUFM knockdown decreased the protective effect of DMF.Finally,mechanistic studies showed that DMF increased intracellular TUFM levels by protecting TUFM from degradation via the ubiquitin-proteasomal degradation pathway.Our results demonstrate for the first time that DMF protects mitochondrial function and inhibits oxidative stress through TUFM-mediated mitophagy in macrophages,resulting in a shift in the balance of macrophage polarization,thereby attenuating periodontitis.Importantly,this study provides new insights into the prevention of periodontitis.
基金supported by the National Natural Science Foundation of China(21878227,22278309)。
文摘Ethanol synthesis via dimethyl oxalate hydrogenation has garnered increasing attention in the fields of syngas utilization.Althoughε-Fe_(2)C has been identified as a promising active species for DMO hydrogenation to ethanol,its formation is kinetically challenging during carbonization.In this work,a Fe_(4)N phase was first synthesized by pretreating a 30Fe/SiO_(2)catalyst in an ammonia environment,followed by carbonization in a methanol-H_(2) flow to obtain ε-Fe_(2)C as the active phase.Fe_(4)N,rather than Fe-O-Si,facilitates the transformation into iron carbide during the carbonization process.The transformation pathway of iron nitride(Fe_(x)N)is mediated by intermediate iron carbonyl species(Fe-CO),ultimately leading to the formation of iron carbide as the active phase.The resulting catalyst exhibited 40 times higher catalytic activity than the untreated catalyst in DMO hydrogenation.Combined structure properties and DFT calculation revealed that the lower energy barrier ofε-Fe_(2)C for ester hydrogenation underpins/strengthens its superior performance,while the STY of ε-Fe_(2)C is 2.8 times that ofε'-Fe_(2.2)C and 58 times that ofχ-Fe_(5)C_(2).This study provides a novel strategy for designing highly efficient iron carbide catalysts for the esters hydrogenation system.
基金supported by the National Natural Science Foundation of China(Nos.22272078 and 52371196)the National Key Research and Development Programof the Ministry of Science and Technology of China(No.2020YFA0406102)the“Innovation and Entrepreneurship of Talents plan”of Jiangsu Province.
文摘The direct conversion of greenhouse gas CO_(2) and low-cost CH3OH into valuable dimethyl carbonate(DMC)offers a promising low-carbon synthetic pathway,but the slow CO_(2) activation kinetics and entropy-decreasing nature of this reaction significantly restrict DMC yield to below 1%.In this work,2-cyanopyridine(2-CP)was employed as a dehydrating agent to suppress the reverse reaction between DMC and H_(2)O,shifting the thermodynamic equilibrium in favor of DMC production.Under this thermodynamic unconstrained condition,increasing oxygen vacancies,especially in the form of oxygen vacancy clusters,promotes catalytic activity significantly.We achieve a catalytic activity of 211 mmol/(g·h)at 140℃ on H_(2)-treated,oxygen-vacancy-clusters-rich CeO_(2) in the presence of 2-CP,a 1.6-fold increase compared to the activity with air-treated CeO_(2) under identical conditions.The DMC yield reaches 8.54%in a 20mL CH3OH solution with 2-CP,surpassing the calculated DMC yield of about 0.66%from the reaction equilibrium constant under the same conditions and without using the dehydrating agent.This work suggests the importance of using a dehydrating agent and also highlights oxygen vacancy clusters as pivotal active sites to promote DMC synthesis.Achieving sustainable DMC synthesis requires further exploration,encompassing strategies such as methods for regeneration of 2-CP.
基金support from National Natural Science Foundation of China(52161016)Joint Key Project of Agricultural Fundamental Research in Yunnan Province(202101BD070001-017)+2 种基金Yunnan Provincial Academician Workstation(202305AF150009)Special Project of“Top Young Talents”of Yunnan Ten Thousand Talents Plan(51900109)Special Project of“Leading Talents of Industrial Technology”of Yunnan Ten Thousand Talents Plan(80201408)are acknowledged.
文摘A biodegradable and green organic compound octadecyl dimethyl benzyl amm-onium chloride(ODBAC)was used as an efficient inhibitor for cold rolled steel(CRS)in phosphoric acid(H_(3)PO_(4)).The mechanism of adsorption and film formation of ODBAC on CRS was studied through experimental and theoretical calculations.The weight loss method shows that the inhibition efficiency of ODBAC can reach 92.01%at a concentration of 10 mg·L^(-1).The adsorption of ODBAC on the CRS surface conforms to the Langmuir isotherm model,which is a mixed adsorption mainly based on physical adsorption.The X-ray photoelectron spectroscopy(XPS)and contact angle results confirmed the existence of the ODBAC film and steel surface's hydrophobicity has been significantly enhanced.Electrochemical test results reveal that the film's formation mainly inhibits the cathodic corrosion reaction and effectively increases the charge transfer resistance.Quantum chemical calculations have found that N18 in ODBAC and C24 and C25 on the benzene ring are the key active adsorption sites.Molecular dynamics simulation results indicate that ODBAC can sharply reduce the free fraction volume to 8%and inhibit the diffusion of corrosion particles,meaning that the formed ODBAC film makes it difficult for corrosion particles to penetrate,thus improving the corrosion resistance of CRS in H_(3)PO_(4).
基金the financial support from the National Natural Science Foundation of China(No.21962015)the Bingtuan Graduate Innovation Project 2024(No.BTYJXM-2024-K12)。
文摘The hydrogenation of dimethyl oxalate(DMO)to ethanol(Et OH)represents a promising avenue for syngas conversion and plays a pivotal role in advancing sustainable energy economies.Nevertheless,designing catalysts with high Et OH yields at low temperatures remains a significant challenge.This study introduces an efficient catalyst featuring a rich SiO_(2)-Ni_(3)Mo_(3)N interface,which achieved a remarkable 97.5%Et OH yield at 210°C and 2 MPa.Impressively,an Et OH yield of 95%was also obtained at 210°C and 1.5 MPa.The research demonstrates that the addition of SiO_(2)fosters the development of a rich SiO_(2)-Ni_(3)Mo_(3)N interface,which enhances the concentration of Lewis acid sites(L-acid)and Brønsted acids sites(B-acid)within the catalyst.This enhancement promotes the adsorption of raw material and intermediate products while increasing H_(2)adsorption,thereby boosting the catalyst's deep hydrogenation capacity.Density functional theory(DFT)simulations indicate that SiO2incorporation modifies the catalyst's metal d-band center through electron transfer,increasing its adsorption capability for raw materials and intermediates and facilitating Et OH production.Consequently,this study achieves high Et OH yields at low temperatures,advances the industrialization process of syngas to Et OH conversion,and offers novel insights into constructing highly active catalytic interfaces for DMO hydrogenation.
文摘Poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate)(PETG)possesses excellent properties and stability than traditional poly(ethylene terephthalate)(PET).However,the production and application of PETG are restricted by the expensive monomer(1,4-cyclohexanedimethanol,CHDM).Direct upgrading of waste PET to dimethyl cyclohexane-1,4-dicarboxylate(DMCD)can promote the production of CHDM in large scale.In this work,a bifunctional Ru/UiO-66_(def)-SO_(3)H catalyst was synthesized and utilized in coupled methanolysis(of waste PET to dimethyl terephthalate(DMT))and hydrogenation(of DMT to DMCD)under mild condition.Characterizations revealed that Ru/UiO-66_(def)-SO_(3)H possessed mesopores(dominant channels of 2.72 and 3.44 nm),enlarged surface area(998 m^(2)·g^(–1)),enhanced acidity(580μmol·g^(–1)),and Ru nanoparticles(NPs)dispersed highly(45.1%)compared to those of Ru/UiO-66.These combined advantages could accelerate the methanolysis and hydrogenation reactions simultaneously,promoting the performance of direct upgrading of PET to DMCD in one pot.In particular,the conversion of PET and yield of DMCD over Ru/UiO-66_(def)-SO_(3)H reached 100%and 97.7%at 170℃and 3 MPa H_(2)within 6 h.Moreover,Ru/UiO-66_(def)-SO3H was also capable for the upcycling of waste PET-based products including beverage bottles,textile fiber and packaging film to DMCD.
基金supported by China National Natural Science Foundation(22008260,21908123)。
文摘Mordenite with different Si/Al ratios were synthesized by solvent-free method and used for dimethyl ether(DME)carbonylation reaction.The influence of Si/Al ratio in the feedstock on the structure,porosity and acid sites were systematically investigated.The characterization results showed that with the increase of Si/Al ratio in the feedstock,part of silicon species fail to enter the skeleton and the specific surface area and pore volume of the samples decreased.The amount of weak acid and medium strong acid decreased alongside with the increasing Si/Al ratio,and the amount of strong acid slightly increased.The Al atoms preferentially enter the strong acid sites in the 8 member ring(MR)channel during the crystallization process.The high Si/Al ratio sample had more acid sites located in the 8 MR channel,leading to more active sites for carbonylation reaction and higher catalytic performance.Appropriately increasing the Si/Al ratio was beneficial for the improvement of carbonylation reaction activity over the mordenite(MOR)catalyst.
基金partly supported by the National Key R&D Program of China(2022YFB4101602)the National Natural Science Foundation of China(22078052)the Fundamental Research Funds for the Central Universities(DUT22ZD207)。
文摘Compared with organic electrolytes,aqueous electrolytes exhibit significantly higher ionic conductivity and possess inherent safety features,showcasing unique advantages in supercapacitors.However,challenges remain for low-salt aqueous electrolytes operating at high voltage and low temperature.Herein,we report a low-salt(0.87 m,m means mol kg^(-1))'salt in dimethyl sulfoxide/water'hybrid electrolyte with non-flammability via hybridizing aqueous electrolyte with an organic co-solvent of dimethyl sulfoxide(hydrogen bond acceptor).As a result,the 0.87 m hybrid electrolyte exhibits enhanced electrochemical stability,a freezing temperature below-50℃,and an outstanding ionic conductivity of 0.52mS cm~(-1)at-50℃.Dimethyl sulfoxide can anchor water molecules through intermolecular hydrogen bond interaction,effectively reinforcing the stability of water in the hybrid electrolyte.Furthermore,the interaction between dimethyl sulfoxide and water molecules diminishes the involvement of water in the generation of ordered ice crystals,finally facilitating the low-temperature performance of the hybrid electrolyte.When paired with the 0.87 m'salt in dimethyl sulfoxide/water'hybrid electrolyte,the symmetric supercapacitor presents a 2.0 V high operating voltage at 25℃,and can operate stably at-50℃.Importantly,the suppressed electrochemical reaction of water at-50℃further leads to the symmetric supercapacitor operated at a higher voltage of 2.6 V.This modification strategy opens an effective avenue to develop low-salt electrolytes for high-voltage and low-temperature aqueous supercapacitors.
基金supported by the Liaoning Provincial Natural Science Foundation Joint Fund for Innovation Capability Improvement(2021-NLTS-12-02)Key Research and Local Service Projects of the Liaoning Provincial Department of Education(LDB2019005).
文摘It is well known that calcium oxide (CaO) has better catalytic efficiency than most heterogeneous catalysts in many transesterification reactions. However, the gradual deactivation problem prevents its large-scale application in industry. In this paper, the deactivation mechanism of CaO in a fixed-bed reactor is investigated based on the transesterification reaction of propylene carbonate and methanol. The leaching amount of CaO during the reaction was estimated by the concentration of Ca in the products. The pretreated and recovered catalysts were characterized by FT-IR, XRD, TG-MS and SEM-EDS. It is evident from experiments and characterization that the deactivation process of CaO is accompanied by the leaching of calcium species and the generation of CaCO3, which are also verified by DFT calculations. At high temperature and high weight hourly space velocity, the deactivation was attributed to the formation of dense CaCO3 shell, which prevents the contact between the feedstock and the active species inside.
基金supported by the National Key Research and Development Program of China(2022YFB4101800)National Natural Science Foundation of China(22278077,22108040)+2 种基金Key Program of Qingyuan Innovation Laboratory(00221004)Research Program of Qingyuan Innovation Laboratory(00523006)Natural Science Foundation of Fujian Province(2022J02019)。
文摘Dimethyl carbonate(DMC)is a crucial chemical raw material widely used in organic synthesis,lithiumion battery electrolytes,and various other fields.The current primary industrial process employs a conventional sodium methoxide basic catalyst to produce DMC through the transesterification reaction between vinyl carbonate and methanol.However,the utilization of this catalyst presents several challenges during the process,including equipment corrosion,the generation of solid waste,susceptibility to deactivation,and complexities in separation and recovery.To address these limitations,a series of alkaline poly(ionic liquid)s,i.e.[DVBPIL][PHO],[DVCPIL][PHO],and[TBVPIL][PHO],with different crosslinking degrees and structures,were synthesized through the construction of cross-linked polymeric monomers and functionalization.These poly(ionic liquid)s exhibit cross-linked structures and controllable cationic and anionic characteristics.Research was conducted to investigate the effect of the cross-linking degree and structure on the catalytic performance of transesterification in synthesizing DMC.It was discovered that the appropriate cross-linking degree and structure of the[DVCPIL][PHO]catalyst resulted in a DMC yield of up to 80.6%.Furthermore,this catalyst material exhibited good stability,maintaining its catalytic activity after repeated use five times without significant changes.The results of this study demonstrate the potential for using alkaline poly(ionic liquid)s as a highly efficient and sustainable alternative to traditional catalysts for the transesterification synthesis of DMC.
文摘Background:Complementary medicine is an interesting field for extracting bio-active compounds from various plant and animal sources.The hepatoprotective effect of the methanolic extract of a species of sea cucumber called Holothuria leu-cospilota in an animal model of liver cancer caused by dimethyl nitrosamine(DMN)was studied.Methods:Wistar female rats were randomly divided into five groups(n=12):control(intact),positive control(received 1%DMN[10 mg/kg/week,intraperitoneally]for 12 weeks),and three treatment groups(received 50,100,and 200 mg/kg/day H.leu-cospilota extract orally for 12 weeks along with intraperitoneal administration of 1%DMN[10 mg/kg/week]).In all groups,ultrasound was performed on the liver every week to check its density.Blood sampling and liver isolation were performed on three occasions,at 4,8,and 12 weeks,to check liver enzymes and the histopathological condition of the liver tissue(every week,four animals from each group were randomly selected).Results:Liver density changes were evident from the eighth week onward in the positive control group.Histopathological results indicated pathologic changes in the positive control group after 4 weeks.The increase in liver enzymes in the posi-tive control group was significantly different from that in the treatment and control groups.Conclusions:We demonstrated the hepatoprotective effect of H.leucospilota on DMN-induced liver damage in rats using biochemical and histological parameters and ultrasonography.More additional research(in silico or in vitro)is needed to find the exact mechanism and the main biological compound in H.leucospilota.
文摘The direct synthesis of dimethyl carbonate(DMC)from CO_(2)and methanol has attracted much attention as an environmentally benign and alternative route for conventional routes.Herein,a series of cerium oxide catalysts with various textural features and surface properties were prepared by the one-pot synthesis method for the direct DMC synthesis from CO_(2)and methanol,and the structure-performance relationship was investigated in detail.Characterization results revealed that both of surface acid-base properties and the oxygen vacancies contents decreased with the rising crystallinity at increasingly higher calcination temperature accompanied by an unexpectedly volcano-shaped trend of DMC yield observed on the catalysts.In situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)studies indicated that the adsorption rate of methanol is slower than that of CO_(2)and the methanol activation state largely influences the formation of key intermediate.Although the enhanced surface acidity-basicity and oxygen vacancies brought by low-temperature calcination could facilitate the activation of CO_(2),the presence of excess strongly basic sites on low-crystallinity sample was detrimental to DMC synthesis due to the preferred formation of unreactive mono/polydentate carbonates as well as the further impediment of methanol activation.Moreover,with the use of 2-cyanopyridine as a dehydration reagent,the DMC synthesis was found to be both influenced by the promotion from the rapid in situ removal of water and the inhibition from the competitive adsorption of hydration products on the same active sites.
基金supported by National Natural Science Foundation of China (No.22102147 and 22002151)State Key Laboratory of Chemical Engineering (No.SKL-ChE-22A02)+2 种基金Zhejiang Provincial Natural Science Foundation of China under Grant No.LQ21B030009the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDA29050300)Qinchuang Yuan high-level innovation and entrepreneurship talents implementing project (No.QCYRCXM-2022-177)。
文摘Product selectivity and reaction pathway are highly dependent on surface structure of heterogeneous catalysts.For vapor-phase hydrogenation of dimethyl oxalate(DMO),"EG route"(DMO→methyl glycolate(MG)ethylene glycol(EG)→ethanol(ET))and"MA route"(DMO→MG→methyl acetate(MA))were proposed over traditional Cu based catalysts and Mo-based or Fe-based catalysts,respectively.Herein,tunable yield of ET(93.7%)and MA(72.1%)were obtained through different reaction routes over WO_(x) modified Cu/SiO_(2) catalysts,and the corresponding reaction route was further proved by kinetic study and in-situ DRIFTS technology.Mechanistic studies demonstrated that H_(2) activation ability,acid density and Cu-WO_(x) interaction on the catalysts were tuned by regulating the surface W density,which resulted in the different reaction pathway and product selectivity.What's more,high yield of MA produced from DMO hydrogenation was firstly reported with the H_(2) pressure as low as 0.5 MPa.
基金financially supported by National Natural Science Foundation of China(U21A20306,21978066)Hebei Province Fig.7.Reaction mechanism of selective hydrogenation of TDC over Rh-based catalysts.Graduate Innovation Funding Project(CXZZBS2023033).
文摘The selective hydrogenation of dimethyl toluene-2,4-dicarbamate(TDC)to methyl cyclohexyl-2,4-dicarbamate(also called hydrogenated TDC,HTDC)is an essential process for non-phosgene synthesis of methylcyclohexane-2,4-diisocyanate.Herein,we prepared a series of supported Rh-based catalysts by the excessive impregnation method and investigated their catalytic performance for the selective hydrogenation of TDC.The emphasis was put on the influence of support properties on the catalytic performance.Among the prepared catalysts,Rh/g-Al_(2)O_(3)performed the best:a HTDC yield of 88.4%was achieved with a 100%conversion of TDC under the conditions of 100℃,3 MPa and 1 h.Furthermore,Rh/γ-Al_(2)O_(3)could be repetitively used for 4 times without a significant loss of its catalytic activity.TEM,XRD,N_(2)adsorption-desorption,H_(2)-TPR,NH_(3)/CO_(2)-TPD,XPS and ICP characterizations were employed to distinguish the properties of the prepared catalysts and the results were correlated with their catalytic performance.It is indicated that the yield of HTDC shows a positive relevance with the percentage of moderate-to-strong acid sites and the content of Rh^(n+)(n≥3)in the catalysts.High values of the percentage and the content can promote a strong interaction between Rh nanoparticles and the supports,facilitating both the transfer of electrons from Rh to the support and the formation of Rh^(n+)species.This is conducive to activating the benzene ring of TDC and thereby improving the yield of HTDC.
文摘Dimethyl ether carbonylation to methyl acetate was comparatively investigated over mor- denite supported copper （Cu/HMOR） catalysts prepared by different methods including evaporation, urea hydrolysis, incipient wetness impregnation and ion-exchange. The results showed that Cu/HMOR prepared via iron-exchange method exhibited the highest catalytic activity due to the synergistic effect of active-site metal and acidic molecular sieve support. Conversion of 95.3% and methyl acetate selectivity of 94.9% were achieved under conditions of 210℃, 1.5 MPa, and GSHV of 4883 h-1. The catalysts were characterized by nitrogen absorption, X-ray diffraction, NH3 temperature program desorption, and CO temperature program desorption techniques. It was found that Cu/HMOR prepared by ion-exchange method possessed high surface area, moderate strong acid centers, and CO adsorption centers, which improved catalytic performance for the reaction of CO insertion to dimethyl ether.
基金This work was supported by the National Natural Science Foundation of China （No.51006110 and No.51276183） and the National Natural Research Foundation of China/Japan Science and Technology Agency （No.51161140331）.
文摘The effect of calcination temperature on the catalytic activity for the dimethyl ether （DME） carbonylation into methyl acetate （MA） was investigated over mordenite supported copper （Cu/HMOR） prepared by ion-exchange process. The results showed that the catalytic activity was obviously affected by the calcination temperature. The maximal DME conversion of 97.2% and the MA selectivity of 97.9% were obtained over the Cu/HMOR calcined at 430 ℃ under conditions of 210 ℃, 1.5 MPa, and GSHV of 4883 h^-1. The obtained Cu/HMOR catalysts were characterized by powder X-ray diffraction, N2 absorption, NH3 temperature program desorption, CO temperature program desorption, and Raman techniques. Proper calcination temperature was effective to promote copper ions migration and diffusion, and led the support HMOR to possess more acid activity sites, which exhibited the complete decomposing of copper nitrate, large surface area and optimum micropore structure, more amount of CO adsorption site and proper amount of weak acid centers.
