BACKGROUND:Patients with diabetes mellitus(DM)are vulnerable to community-acquired pneumonia(CAP),which have a high mortality rate.We aimed to investigate the value of heparin-binding protein(HBP)as a prognostic marke...BACKGROUND:Patients with diabetes mellitus(DM)are vulnerable to community-acquired pneumonia(CAP),which have a high mortality rate.We aimed to investigate the value of heparin-binding protein(HBP)as a prognostic marker of mortality in patients with DM and CAP.METHODS:This retrospective study included CAP patients who were tested for HBP at intensive care unit(ICU)admission from January 2019 to April 2020.Patients were allocated to the DM or non-DM group and paired with propensity score matching.Baseline characteristics and clinical outcomes up to 90 days were evaluated.The primary outcome was the 10-day mortality.Receiver operating characteristic(ROC)curves,Kaplan-Meier analysis,and Cox regression were used for statistical analysis.RESULTS:Among 152 enrolled patients,60 pairs were successfully matched.There was no significant difference in 10-day mortality,while more patients in the DM group died within 28 d(P=0.024)and 90 d(P=0.008).In the DM group,HBP levels at ICU admission were higher in 10-day non-survivors than in 10-day survivors(median 182.21[IQR:55.43-300]ng/ml vs.median 66.40[IQR:34.13-107.85]ng/mL,P=0.019),and HBP levels could predict the 10-day mortality with an area under the ROC curve of 0.747.The cut-off value,sensitivity,and specificity were 160.6 ng/mL,66.7%,and 90.2%,respectively.Multivariate Cox regression analysis indicated that HBP was an independent prognostic factor for 10-day(HR 7.196,95%CI:1.596-32.455,P=0.01),28-day(HR 4.381,95%CI:1.449-13.245,P=0.009),and 90-day mortality(HR 4.581,95%CI:1.637-12.819,P=0.004)in patients with DM.CONCLUSION:Plasma HBP at ICU admission was associated with the 10-day,28-day,and 90-day mortality,and might be a prognostic factor in patients with DM and CAP.展开更多
Colorectal cancer has a high incidence and mortality rate in China, with the majority of cases being middle and low rectal cancer. Surgical intervention is currently the main treatment modality for locally advanced re...Colorectal cancer has a high incidence and mortality rate in China, with the majority of cases being middle and low rectal cancer. Surgical intervention is currently the main treatment modality for locally advanced rectal cancer, with the common goal of improving oncological outcomes while preserving function. The controversy regarding the circumferential resection margin distance in rectal cancer surgery has been resolved. With the promotion of neoadjuvant therapy concepts and advancements in technology, treatment strategies have become more diverse.Following tumor downstaging, there is an increasing trend towards extending the safe distance of distal rectal margin. This provides more opportunities for patients with low rectal cancer to preserve their anal function.However, there is currently no consensus on the specific distance of distal resection margin.展开更多
The build-up of misfoldedα-synuclein(α-syn)in the central nervous system is the pathological hallmark of a number of neurodegenerative diseases that are known asα-synucleinopathies.These include Parkinson’s diseas...The build-up of misfoldedα-synuclein(α-syn)in the central nervous system is the pathological hallmark of a number of neurodegenerative diseases that are known asα-synucleinopathies.These include Parkinson’s disease(PD),Parkinson’s disease with dementia(PDD),dementia with Lewy body(LB),multiple system atrophy(MSA),and a subset of Alzheimer’s disease.Growing evidence underscores that the intercellular transmission and amplification of pathologicalα-syn are critical processes underlying the progression ofα-synucleinopathies(Peng et al.,2020),and as such,the study of these processes could lead to the identification of promising therapeutics to mitigate disease progression.Most previous studies have focused solely on pathological seeds in relation to disease progression.展开更多
Hierarchical SAPO‐34 crystals were synthesized by a facile acid etching post‐treatment. Butterfly‐shaped porous patterns on four side faces and hierarchical pores composed of micropores,mesopores and macropores wer...Hierarchical SAPO‐34 crystals were synthesized by a facile acid etching post‐treatment. Butterfly‐shaped porous patterns on four side faces and hierarchical pores composed of micropores,mesopores and macropores were formed after a nitric acid or oxalic acid treatment. The catalyticperformance of the hierarchical SAPO‐34 for the methanol to olefins (MTO) process showed that thesynergistic effect of the hierarchical pores and acid sites resulted in a longer catalyst lifetime (from210 to 390 min for the acid treated SAPO‐34) and higher selectivity to light olefins of 92%–94%.The ethylene selectivity can be adjusted between 37.4% and 51.5% by the pore size. No hierarchical SAPO‐34 was obtained after a treatment with butanedioic acid, and with this sample, fast deactivation was detected after 100 min.展开更多
Cu-Fe composite oxides were prepared by co-precipitation method and tested for higher alcohol synthesis from syngas. The selectivity to C2＋OH and C6＋OH in alcohol distribution was very high while the methane product...Cu-Fe composite oxides were prepared by co-precipitation method and tested for higher alcohol synthesis from syngas. The selectivity to C2＋OH and C6＋OH in alcohol distribution was very high while the methane product fraction in hydrocarbon distribution was rather low, demonstrating a promising potential in higher alcohols synthesis from syngas. The distribution of alcohols and hydrocarbons approximately obeyed Anderson-Schulz-Flory distribution with similar chain growth probability, indicating alcohols and hydrocarbons derived from the same intermediates. The effects of Cu/Fe molar ratio, reaction temperature and gas hourly space velocity （GHSV） on catalytic performance were studied in detail. The sample with a Cu/Fe molar ratio of 10/1 exhibited the best catalytic performance. Higher reaction temperature accelerated water-gas-shift reaction and led to lower total alcohols selectivity. GHSV showed great effect on catalytic performance and higher GHSV increased the total alcohol selectivity, indicating there existed visible dehydration reaction of alcohol into hydrocarbon.展开更多
A novel melting-assisted solvent-free route using solid oxalic acid was proposed for the post-treatment of SAPO-11 zeolite,followed by loading with 0.5 wt%Pt by the incipient wetness impregnation method.Subsequently,t...A novel melting-assisted solvent-free route using solid oxalic acid was proposed for the post-treatment of SAPO-11 zeolite,followed by loading with 0.5 wt%Pt by the incipient wetness impregnation method.Subsequently,the performance of the obtained bifunctional catalysts toward the hydroisomerization of n-dodecane was examined.The prepared samples were characterized by XRD,SEM,BET,XRF,Py-IR,and solid-state NMR.From the results,it was found that the high crystallinity and uniform morphology were retained after the post-treatment and that more(002)crystal faces were exposed,which was beneficial since more acid sites were provided.More importantly,the total Bronsted acid sites and the ratio(Ra)of the micropore area to the total surface area were optimized by this method.Thus,the catalytic performance was enhanced significantly,and the prepared Pt-SAPO-11-10%catalyst had the highest i-dodecane yield of 80.1%compared to 55.3%of Pt-SAPO-11.Expectedly,this facile and cost-effective method is promising for the hydroisomerization of normal paraffin in the production of lubricant base oils.展开更多
Density‐functional theory calculations were carried out to study the strontium(Sr)‐doping effect on methane activation over a lanthanum‐oxide(La2O3)catalyst for the oxidative coupling of methane(OCM)using the clust...Density‐functional theory calculations were carried out to study the strontium(Sr)‐doping effect on methane activation over a lanthanum‐oxide(La2O3)catalyst for the oxidative coupling of methane(OCM)using the cluster model.Eight Sr‐doped La2O3cluster models were built from pure La2O3clusters that were used previously to model the La2O3catalyst.These form two distinct categories,namely,those without a radical character(LaSrO2(OH),La2SrO4,La3SrO5(OH),and La5SrO8(OH))and those with a radical character(LaSrO3,La2SrO4(OH),La3SrO6,and La5SrO9).The potential‐energy surface for CH4activation to form a CH3radical at different Sr-O and La-O pair sites on these Sr‐doped La2O3clusters was calculated to study the Sr‐doping effect on the OCM catalytic activity.CH4physisorption and chemisorption energies,and activation barriers,and CH3desorption energies were predicted.Compared with the pure La2O3clusters,in general,the Sr‐doped La2O3clusters are thermodynamically and kinetically more reactive with CH4.For the Sr‐doped La2O3clusters without the radical character,the Sr-O pair site is more reactive with CH4than the La-O pair site,although a direct release of the CH3radical is also highly endothermic as in the case of the pure La2O3clusters.In contrast,for the Sr‐doped La2O3clusters with a radical character,the activation of CH4at the oxygen radical site and the release of the CH3radical are much easier.Thus,our calculations suggest that the Sr dopant prompts the OCM catalytic activity of the La2O3catalyst by providing a highly active oxygen‐radical site and by strengthening the basicity of the M-O pair site,which leads to lower CH4activation energies and lower CH3desorption energies.展开更多
A reaction-coupling strategy is often employed for CO_(2)hydrogenation to produce fuels and chemicals using oxide/zeolite bifunctional catalysts.Because the oxide components are responsible for CO_(2)activation,unders...A reaction-coupling strategy is often employed for CO_(2)hydrogenation to produce fuels and chemicals using oxide/zeolite bifunctional catalysts.Because the oxide components are responsible for CO_(2)activation,understanding the structural effects of these oxides is crucial,however,these effects still remain unclear.In this study,we combined In_(2)O_(3),with varying particle sizes,and SAPO‐34 as bifunctional catalysts for CO_(2)hydrogenation.The CO_(2)conversion and selectivity of the lower olefins increased as the average In_(2)O_(3)crystallite size decreased from 29 to 19 nm;this trend mainly due to the increasing number of oxygen vacancies responsible for CO_(2) and H_(2) activation.However,In_(2)O_(3)particles smaller than 19 nm are more prone to sintering than those with other sizes.The results suggest that 19 nm is the optimal size of In_(2)O_(3)for CO_(2)hydrogenation to lower olefins and that the oxide particle size is crucial for designing catalysts with high activity,high selectivity,and high stability.展开更多
Palladium oxide(PdOx)and cobalt oxide(Co3O4)are efficient catalysts for methane(CH4)combustion,and Pd‐doped Co3O4catalysts have been found to exhibit better catalytic activities,which suggest synergism between the tw...Palladium oxide(PdOx)and cobalt oxide(Co3O4)are efficient catalysts for methane(CH4)combustion,and Pd‐doped Co3O4catalysts have been found to exhibit better catalytic activities,which suggest synergism between the two components.We carried out first‐principles calculations at the PBE+U level to investigate the Pd‐doping effect on CH4reactivity over the Co3O4catalyst.Because of the structural complexity of the Pd‐doped Co3O4catalyst,we built Pd‐doped catalyst models using Co3O4(001)slabs with two different terminations and examined CH4reactivity over the possible Pd?O active sites.A low energy barrier of0.68eV was predicted for CH4dissociation over the more reactive Pd‐doped Co3O4(001)surface,which was much lower than the0.98and0.89eV that was predicted previously over the more reactive pure Co3O4(001)and(011)surfaces,respectively.Using a simple model,we predicted CH4reaction rates over the pure Co3O4(001)and(011)surfaces,and Co3O4(001)surfaces with different amounts of Pd dopant.Our theoretical results agree well with the available experimental data,which suggests a strong synergy between the Pd dopant and the Co3O4catalyst,and leads to a significant increase in CH4reaction rate.展开更多
Co2C‐based catalysts with SiO2,γ‐Al2O3,and carbon nanotubes(CNTs)as support materials were prepared and evaluated for the Fischer‐Tropsch to olefin(FTO)reaction.The combination of catalytic performance and structu...Co2C‐based catalysts with SiO2,γ‐Al2O3,and carbon nanotubes(CNTs)as support materials were prepared and evaluated for the Fischer‐Tropsch to olefin(FTO)reaction.The combination of catalytic performance and structure characterization indicates that the cobalt‐support interaction has a great influence on the Co2C morphology and catalytic performance.The CNT support facilitates the formation of a CoMn composite oxide during calcination,and Co2C nanoprisms were observed in the spent catalysts,resulting in a product distribution that greatly deviates from the classical Anderson‐Schulz‐Flory(ASF)distribution,where only 2.4 C%methane was generated.The Co3O4 phase for SiO2‐andγ‐Al2O3‐supported catalysts was observed in the calcined sample.After reduction,CoO,MnO,and low‐valence CoMn composite oxide were generated in theγ‐Al2O3‐supported sample,and both Co2C nanospheres and nanoprisms were identified in the corresponding spent catalyst.However,only separated phases of CoO and MnO were found in the reduced sample supported by SiO2,and Co2C nanospheres were detected in the spent catalyst without the evidence of any Co2C nanoprisms.The Co2C nanospheres led to a relatively high methane selectivity of 5.8 C%and 12.0 C%of theγ‐Al2O3‐and SiO2‐supported catalysts,respectively.These results suggest that a relatively weak cobalt‐support interaction is necessary for the formation of the CoMn composite oxide during calcination,which benefits the formation of Co2C nanoprisms with promising catalytic performance for the sustainable production of olefins via syngas.展开更多
The directly selective hydrogenolysis of xylitol to ethylene glycol(EG) and 1,2-propylene glycol(1,2-PDO)was performed on Cu–Ni–ZrO_2 catalysts prepared by a co-precipitation method. Upon optimizing the reaction con...The directly selective hydrogenolysis of xylitol to ethylene glycol(EG) and 1,2-propylene glycol(1,2-PDO)was performed on Cu–Ni–ZrO_2 catalysts prepared by a co-precipitation method. Upon optimizing the reaction conditions(518 K, 4.0 MPaH_2 and 3 h), 97.0% conversion of xylitol and 63.1% yield of glycols were obtained in water without extra inorganic base. The catalyst still remained stable activity after six cycles and above 80% total selectivity of glycols was obtained when using 20.0% xylitol concentration. XRD, TEM and ICP results indicated that Cu–Ni–ZrO_2 catalysts possess favorable stability. Cu and Ni are beneficial to the cleavage of C–O and C–H bond, respectively. To reduce the hydrogen consumption, isopropanol was added as in-situ hydrogen source and 96.4% conversion of xylitol with 43.6% yield of glycols were realized.展开更多
Natural gas and shale gas,with methane as the main component,are important and clean fossil energy resources.Direct catalytic conversion of methane to valuable chemicals is considered a crown jewel topic in catalysis....Natural gas and shale gas,with methane as the main component,are important and clean fossil energy resources.Direct catalytic conversion of methane to valuable chemicals is considered a crown jewel topic in catalysis.Substantial studies on processes including methane reforming,oxidative coupling of methane,non-oxidative coupling of methane,etc.have been conducted for many years.However,owing to the intrinsic chemical inertness of CH4,harsh reaction conditions involving either extremely high temperatures or highly oxidative reactants are required to activate the C–H bonds of CH4 in such thermocatalytic processes,which may cause the target products,such as ethylene or methanol,to be further converted into coke or CO and CO2.It is desirable to adopt a new strategy for direct CH4 conversion under mild conditions.Herein,we report that efficient electrocatalytic oxidation of methane to alcohols at ambient temperature and pressure can be achieved using a NiO/Ni hollow fiber electrode.This work opens a new avenue for direct catalytic conversion of CH4.展开更多
The X-ray photoelectron spectroscopy （XPS） was used to investigate the surface characteristic of potassium-promoted or un-promoted both β-Mo2C and α-MoC1-x pretreated by syngas at different temperatures,and the pr...The X-ray photoelectron spectroscopy （XPS） was used to investigate the surface characteristic of potassium-promoted or un-promoted both β-Mo2C and α-MoC1-x pretreated by syngas at different temperatures,and the promotional effect of potassium on the catalytic performance was also studied.XPS results revealed that the content of surface Mo and its valence distribution between β-Mo2C and α-MoC1-x were quite different.Promoted by potassium,the remarkable changes were observed for surface composition and valence of Mo distribution over β-Mo2C.Potassium had strong electronic effect on β-Mo2C,which led to a higher Mo4＋ content.On the contrary,potassium had little electronic effect on α-MoC1-x,and K-Mo interaction was weak.Therefore,Mo0 and Mo2＋ became the dominant species on the catalyst surface,and the Mo4＋ content showed almost no increase as the pretreatment temperature enhanced.In terms of catalytic performance of molybdenum carbides,the increase in Mo0 most likely explained the increase in hydrocarbon selectivity,yet Mo4＋ might be responsible for the alcohols synthesis.展开更多
Nickel and potassium co-modified β-Mo2C catalysts were prepared and used for CO hydrogenation reaction. The major products over β-Mo2C were C1-C4 hydrocarbons, only few alcohols were obtained. Addition of potassium ...Nickel and potassium co-modified β-Mo2C catalysts were prepared and used for CO hydrogenation reaction. The major products over β-Mo2C were C1-C4 hydrocarbons, only few alcohols were obtained. Addition of potassium resulted in remarkable selectivity shift from hydrocarbons to alcohols at the expense of CO conversion over β-Mo2C. Moreover, it was found that potassium enhanced the ability of chain propagation with a higher C2＋OH production. Modified by nickel,β-Mo2C showed a relatively high CO conversion, however, the products were similar to those of pure β-Mo2C. When co-modified by nickel and potassium,β-Mo2C exhibited high activity and selectivity towards mixed alcohols synthesis, and also the whole chain propagation to produce alcohols especially for the stage of C1 OH to C2OH was remarkably enhanced. It was concluded that the Ni and K had, to some extent, synergistic effect on CO conversion.展开更多
MnOx-promoted Ni-based catalyst supported by ZnO was developed to selectively hydrogenate glucose into polyols in water at 523 K with a yield of 64.9%. Using glucose, sorbitol, glycerol and LA as the rawmaterials, the...MnOx-promoted Ni-based catalyst supported by ZnO was developed to selectively hydrogenate glucose into polyols in water at 523 K with a yield of 64.9%. Using glucose, sorbitol, glycerol and LA as the rawmaterials, the roles of nickel, ZnO and MnOx were investigated. The results show that nickel provided a new pathway of glucose to sorbitol and played an important role in the hydrogenation of C3 intermediates to 1,2-propanediol(1,2-PDO). The high yield of 1, 2-PDO was attributed to effective C–C bond cleavage performance of ZnO support promoted by MnOx. ZnO and MnOx contribute to the conversion of glycerol to lactic acid(LA) and LA to 1, 2-PDO, respectively. A concise pathway for hydrogenation of glucose over Ni-based catalyst was proposed.展开更多
Chinese fir(Cunninghamia lanceolata(Lamb.)Hook),a fast-growing and economically important timber tree species in China,is widely used in construction,furniture,and paper manufacture but has a long breeding cycle.Chemi...Chinese fir(Cunninghamia lanceolata(Lamb.)Hook),a fast-growing and economically important timber tree species in China,is widely used in construction,furniture,and paper manufacture but has a long breeding cycle.Chemical mutagens,such as ethyl methane sulfonate(EMS)and sodium azide(SA),are widely used in crops such as rice,wheat,cotton,soybean and sugarcane but their utility for tree breeding is unknown.In this study we examined the effects of EMS and S A on Chinese fir seed germination and growth.Chinese fir seeds were treated with the two chemical mutagens;were planted in Jiangle County,Fujian Province,China;and their heights were measured from 2011 to2017.The concentrations and durations of treatment with the two chemical mutagens were significantly associated with the Chinese fir seedling and mortality rates,as well as with the heights of trees from the seedling stage to 3 years old.We also generated 127 mutants with abnormal branches and reproductive growth.We report here the effects of two chemical mutagens on Chinese fir breeding;our data will contribute to knowledge of the utility of EMS and SA in forestry.展开更多
Based on the difference of hydroxy group configuration on the special adsorption and coordination of phosphate on the dispersed α-Fe2O3 nanodisks with diameter of 150-200 nm different planes of α-Fe2O3 nanoparticles...Based on the difference of hydroxy group configuration on the special adsorption and coordination of phosphate on the dispersed α-Fe2O3 nanodisks with diameter of 150-200 nm different planes of α-Fe2O3 nanoparticles, using （001） plane of α-Fe2O3, well-crystallized and well and thickness of 40-80 nm were synthesized via a hydrotherrnal method. The magnetic properties of synthesized nanodisks were investigated. It was found that the nanodisks possessed a saturation magnetization （Ms） of 0.38 emu/g, a rernanent magnetization （Mr） of 0.031 ernu/g and a coercivity of 452.91 Oe at room temperature. The Mr and coercivity of synthesized α-Fe2O3 nanodisks are higher and the Ms is lower than those of other previously reported α-Fe2O3 nanostructures.展开更多
Fe modified and un-modified K/Mo2C were prepared and investigated as catalysts for CO hydrogenation reaction. Compared with K/Mo2C catalyst, the addition of Fe increased the production of alcohols, especially the C2＋...Fe modified and un-modified K/Mo2C were prepared and investigated as catalysts for CO hydrogenation reaction. Compared with K/Mo2C catalyst, the addition of Fe increased the production of alcohols, especially the C2＋OH. Meanwhile, considerable amounts of C5＋ hydrocar- bons and C2= -C4= were formed, whereas methane selectivity greatly decreased. Also, the activity and selectivity of the catalyst were readily affected by the reaction pressure and temperature employed. According to the XPS results, Mo4＋ might be responsible for the production of alcohols, whereas the low valence state of Mo species such as Mo^0 and/or Mo^2＋ might be account for the high activity and selectivity toward hydrocarbons.展开更多
基金supported by the National Key Research and Development Program of China(2021YFC2501800)Leader Project of Henan Province Health Young and Middle-aged Professor(HNSWJW2020013).
文摘BACKGROUND:Patients with diabetes mellitus(DM)are vulnerable to community-acquired pneumonia(CAP),which have a high mortality rate.We aimed to investigate the value of heparin-binding protein(HBP)as a prognostic marker of mortality in patients with DM and CAP.METHODS:This retrospective study included CAP patients who were tested for HBP at intensive care unit(ICU)admission from January 2019 to April 2020.Patients were allocated to the DM or non-DM group and paired with propensity score matching.Baseline characteristics and clinical outcomes up to 90 days were evaluated.The primary outcome was the 10-day mortality.Receiver operating characteristic(ROC)curves,Kaplan-Meier analysis,and Cox regression were used for statistical analysis.RESULTS:Among 152 enrolled patients,60 pairs were successfully matched.There was no significant difference in 10-day mortality,while more patients in the DM group died within 28 d(P=0.024)and 90 d(P=0.008).In the DM group,HBP levels at ICU admission were higher in 10-day non-survivors than in 10-day survivors(median 182.21[IQR:55.43-300]ng/ml vs.median 66.40[IQR:34.13-107.85]ng/mL,P=0.019),and HBP levels could predict the 10-day mortality with an area under the ROC curve of 0.747.The cut-off value,sensitivity,and specificity were 160.6 ng/mL,66.7%,and 90.2%,respectively.Multivariate Cox regression analysis indicated that HBP was an independent prognostic factor for 10-day(HR 7.196,95%CI:1.596-32.455,P=0.01),28-day(HR 4.381,95%CI:1.449-13.245,P=0.009),and 90-day mortality(HR 4.581,95%CI:1.637-12.819,P=0.004)in patients with DM.CONCLUSION:Plasma HBP at ICU admission was associated with the 10-day,28-day,and 90-day mortality,and might be a prognostic factor in patients with DM and CAP.
基金supported by “San Ming” Project of Shenzhen, China (No. SZSM201612051)National Natural Science Foundation of China (No. 81972240)。
文摘Colorectal cancer has a high incidence and mortality rate in China, with the majority of cases being middle and low rectal cancer. Surgical intervention is currently the main treatment modality for locally advanced rectal cancer, with the common goal of improving oncological outcomes while preserving function. The controversy regarding the circumferential resection margin distance in rectal cancer surgery has been resolved. With the promotion of neoadjuvant therapy concepts and advancements in technology, treatment strategies have become more diverse.Following tumor downstaging, there is an increasing trend towards extending the safe distance of distal rectal margin. This provides more opportunities for patients with low rectal cancer to preserve their anal function.However, there is currently no consensus on the specific distance of distal resection margin.
文摘The build-up of misfoldedα-synuclein(α-syn)in the central nervous system is the pathological hallmark of a number of neurodegenerative diseases that are known asα-synucleinopathies.These include Parkinson’s disease(PD),Parkinson’s disease with dementia(PDD),dementia with Lewy body(LB),multiple system atrophy(MSA),and a subset of Alzheimer’s disease.Growing evidence underscores that the intercellular transmission and amplification of pathologicalα-syn are critical processes underlying the progression ofα-synucleinopathies(Peng et al.,2020),and as such,the study of these processes could lead to the identification of promising therapeutics to mitigate disease progression.Most previous studies have focused solely on pathological seeds in relation to disease progression.
基金supported by the National Natural Science Foundation of China (21403279, 21507141, 21506243)the Science and Technology Commission of Shanghai Municipality (14DZ1207602, 14DZ1203700)~~
文摘Hierarchical SAPO‐34 crystals were synthesized by a facile acid etching post‐treatment. Butterfly‐shaped porous patterns on four side faces and hierarchical pores composed of micropores,mesopores and macropores were formed after a nitric acid or oxalic acid treatment. The catalyticperformance of the hierarchical SAPO‐34 for the methanol to olefins (MTO) process showed that thesynergistic effect of the hierarchical pores and acid sites resulted in a longer catalyst lifetime (from210 to 390 min for the acid treated SAPO‐34) and higher selectivity to light olefins of 92%–94%.The ethylene selectivity can be adjusted between 37.4% and 51.5% by the pore size. No hierarchical SAPO‐34 was obtained after a treatment with butanedioic acid, and with this sample, fast deactivation was detected after 100 min.
基金the State Key Fundamental Research Program(Ministry of Science and Technology of China,No.2011CBA00501)Shanghai Municipal Science and Technology Commission,China(Grant No:11DZ1200300)the Foundation of State Key Laboratory of Coal Conversion(Grant No:1112610)
文摘Cu-Fe composite oxides were prepared by co-precipitation method and tested for higher alcohol synthesis from syngas. The selectivity to C2＋OH and C6＋OH in alcohol distribution was very high while the methane product fraction in hydrocarbon distribution was rather low, demonstrating a promising potential in higher alcohols synthesis from syngas. The distribution of alcohols and hydrocarbons approximately obeyed Anderson-Schulz-Flory distribution with similar chain growth probability, indicating alcohols and hydrocarbons derived from the same intermediates. The effects of Cu/Fe molar ratio, reaction temperature and gas hourly space velocity （GHSV） on catalytic performance were studied in detail. The sample with a Cu/Fe molar ratio of 10/1 exhibited the best catalytic performance. Higher reaction temperature accelerated water-gas-shift reaction and led to lower total alcohols selectivity. GHSV showed great effect on catalytic performance and higher GHSV increased the total alcohol selectivity, indicating there existed visible dehydration reaction of alcohol into hydrocarbon.
基金supported by the National Natural Science Foundation of China(21776295)the Youth Innovation Promotion Association,CAS(2017355)~~
文摘A novel melting-assisted solvent-free route using solid oxalic acid was proposed for the post-treatment of SAPO-11 zeolite,followed by loading with 0.5 wt%Pt by the incipient wetness impregnation method.Subsequently,the performance of the obtained bifunctional catalysts toward the hydroisomerization of n-dodecane was examined.The prepared samples were characterized by XRD,SEM,BET,XRF,Py-IR,and solid-state NMR.From the results,it was found that the high crystallinity and uniform morphology were retained after the post-treatment and that more(002)crystal faces were exposed,which was beneficial since more acid sites were provided.More importantly,the total Bronsted acid sites and the ratio(Ra)of the micropore area to the total surface area were optimized by this method.Thus,the catalytic performance was enhanced significantly,and the prepared Pt-SAPO-11-10%catalyst had the highest i-dodecane yield of 80.1%compared to 55.3%of Pt-SAPO-11.Expectedly,this facile and cost-effective method is promising for the hydroisomerization of normal paraffin in the production of lubricant base oils.
基金supported by the National Natural Science Foundation of China(21473233,21403277)the Frontier Science Program of Shell Global Solutions International B.V.(PT32281)+1 种基金the Ministry of Science and Technology of China(2016YFA0202802)the Shanghai Municipal Science and Technology Commission(14ZR1444600)~~
文摘Density‐functional theory calculations were carried out to study the strontium(Sr)‐doping effect on methane activation over a lanthanum‐oxide(La2O3)catalyst for the oxidative coupling of methane(OCM)using the cluster model.Eight Sr‐doped La2O3cluster models were built from pure La2O3clusters that were used previously to model the La2O3catalyst.These form two distinct categories,namely,those without a radical character(LaSrO2(OH),La2SrO4,La3SrO5(OH),and La5SrO8(OH))and those with a radical character(LaSrO3,La2SrO4(OH),La3SrO6,and La5SrO9).The potential‐energy surface for CH4activation to form a CH3radical at different Sr-O and La-O pair sites on these Sr‐doped La2O3clusters was calculated to study the Sr‐doping effect on the OCM catalytic activity.CH4physisorption and chemisorption energies,and activation barriers,and CH3desorption energies were predicted.Compared with the pure La2O3clusters,in general,the Sr‐doped La2O3clusters are thermodynamically and kinetically more reactive with CH4.For the Sr‐doped La2O3clusters without the radical character,the Sr-O pair site is more reactive with CH4than the La-O pair site,although a direct release of the CH3radical is also highly endothermic as in the case of the pure La2O3clusters.In contrast,for the Sr‐doped La2O3clusters with a radical character,the activation of CH4at the oxygen radical site and the release of the CH3radical are much easier.Thus,our calculations suggest that the Sr dopant prompts the OCM catalytic activity of the La2O3catalyst by providing a highly active oxygen‐radical site and by strengthening the basicity of the M-O pair site,which leads to lower CH4activation energies and lower CH3desorption energies.
文摘A reaction-coupling strategy is often employed for CO_(2)hydrogenation to produce fuels and chemicals using oxide/zeolite bifunctional catalysts.Because the oxide components are responsible for CO_(2)activation,understanding the structural effects of these oxides is crucial,however,these effects still remain unclear.In this study,we combined In_(2)O_(3),with varying particle sizes,and SAPO‐34 as bifunctional catalysts for CO_(2)hydrogenation.The CO_(2)conversion and selectivity of the lower olefins increased as the average In_(2)O_(3)crystallite size decreased from 29 to 19 nm;this trend mainly due to the increasing number of oxygen vacancies responsible for CO_(2) and H_(2) activation.However,In_(2)O_(3)particles smaller than 19 nm are more prone to sintering than those with other sizes.The results suggest that 19 nm is the optimal size of In_(2)O_(3)for CO_(2)hydrogenation to lower olefins and that the oxide particle size is crucial for designing catalysts with high activity,high selectivity,and high stability.
基金supported by the National Natural Science Foundation of China(21473233,21403277)the Energy Technologies Institute LLP,UK~~
文摘Palladium oxide(PdOx)and cobalt oxide(Co3O4)are efficient catalysts for methane(CH4)combustion,and Pd‐doped Co3O4catalysts have been found to exhibit better catalytic activities,which suggest synergism between the two components.We carried out first‐principles calculations at the PBE+U level to investigate the Pd‐doping effect on CH4reactivity over the Co3O4catalyst.Because of the structural complexity of the Pd‐doped Co3O4catalyst,we built Pd‐doped catalyst models using Co3O4(001)slabs with two different terminations and examined CH4reactivity over the possible Pd?O active sites.A low energy barrier of0.68eV was predicted for CH4dissociation over the more reactive Pd‐doped Co3O4(001)surface,which was much lower than the0.98and0.89eV that was predicted previously over the more reactive pure Co3O4(001)and(011)surfaces,respectively.Using a simple model,we predicted CH4reaction rates over the pure Co3O4(001)and(011)surfaces,and Co3O4(001)surfaces with different amounts of Pd dopant.Our theoretical results agree well with the available experimental data,which suggests a strong synergy between the Pd dopant and the Co3O4catalyst,and leads to a significant increase in CH4reaction rate.
文摘Co2C‐based catalysts with SiO2,γ‐Al2O3,and carbon nanotubes(CNTs)as support materials were prepared and evaluated for the Fischer‐Tropsch to olefin(FTO)reaction.The combination of catalytic performance and structure characterization indicates that the cobalt‐support interaction has a great influence on the Co2C morphology and catalytic performance.The CNT support facilitates the formation of a CoMn composite oxide during calcination,and Co2C nanoprisms were observed in the spent catalysts,resulting in a product distribution that greatly deviates from the classical Anderson‐Schulz‐Flory(ASF)distribution,where only 2.4 C%methane was generated.The Co3O4 phase for SiO2‐andγ‐Al2O3‐supported catalysts was observed in the calcined sample.After reduction,CoO,MnO,and low‐valence CoMn composite oxide were generated in theγ‐Al2O3‐supported sample,and both Co2C nanospheres and nanoprisms were identified in the corresponding spent catalyst.However,only separated phases of CoO and MnO were found in the reduced sample supported by SiO2,and Co2C nanospheres were detected in the spent catalyst without the evidence of any Co2C nanoprisms.The Co2C nanospheres led to a relatively high methane selectivity of 5.8 C%and 12.0 C%of theγ‐Al2O3‐and SiO2‐supported catalysts,respectively.These results suggest that a relatively weak cobalt‐support interaction is necessary for the formation of the CoMn composite oxide during calcination,which benefits the formation of Co2C nanoprisms with promising catalytic performance for the sustainable production of olefins via syngas.
基金financial supports provided by the National Natural Science Foundation of China (21406255)the Shanghai Science and Technology Committee (16dz1207200)the Youth Innovation Promotion Association CAS (2015231)
文摘The directly selective hydrogenolysis of xylitol to ethylene glycol(EG) and 1,2-propylene glycol(1,2-PDO)was performed on Cu–Ni–ZrO_2 catalysts prepared by a co-precipitation method. Upon optimizing the reaction conditions(518 K, 4.0 MPaH_2 and 3 h), 97.0% conversion of xylitol and 63.1% yield of glycols were obtained in water without extra inorganic base. The catalyst still remained stable activity after six cycles and above 80% total selectivity of glycols was obtained when using 20.0% xylitol concentration. XRD, TEM and ICP results indicated that Cu–Ni–ZrO_2 catalysts possess favorable stability. Cu and Ni are beneficial to the cleavage of C–O and C–H bond, respectively. To reduce the hydrogen consumption, isopropanol was added as in-situ hydrogen source and 96.4% conversion of xylitol with 43.6% yield of glycols were realized.
文摘Natural gas and shale gas,with methane as the main component,are important and clean fossil energy resources.Direct catalytic conversion of methane to valuable chemicals is considered a crown jewel topic in catalysis.Substantial studies on processes including methane reforming,oxidative coupling of methane,non-oxidative coupling of methane,etc.have been conducted for many years.However,owing to the intrinsic chemical inertness of CH4,harsh reaction conditions involving either extremely high temperatures or highly oxidative reactants are required to activate the C–H bonds of CH4 in such thermocatalytic processes,which may cause the target products,such as ethylene or methanol,to be further converted into coke or CO and CO2.It is desirable to adopt a new strategy for direct CH4 conversion under mild conditions.Herein,we report that efficient electrocatalytic oxidation of methane to alcohols at ambient temperature and pressure can be achieved using a NiO/Ni hollow fiber electrode.This work opens a new avenue for direct catalytic conversion of CH4.
文摘The X-ray photoelectron spectroscopy （XPS） was used to investigate the surface characteristic of potassium-promoted or un-promoted both β-Mo2C and α-MoC1-x pretreated by syngas at different temperatures,and the promotional effect of potassium on the catalytic performance was also studied.XPS results revealed that the content of surface Mo and its valence distribution between β-Mo2C and α-MoC1-x were quite different.Promoted by potassium,the remarkable changes were observed for surface composition and valence of Mo distribution over β-Mo2C.Potassium had strong electronic effect on β-Mo2C,which led to a higher Mo4＋ content.On the contrary,potassium had little electronic effect on α-MoC1-x,and K-Mo interaction was weak.Therefore,Mo0 and Mo2＋ became the dominant species on the catalyst surface,and the Mo4＋ content showed almost no increase as the pretreatment temperature enhanced.In terms of catalytic performance of molybdenum carbides,the increase in Mo0 most likely explained the increase in hydrocarbon selectivity,yet Mo4＋ might be responsible for the alcohols synthesis.
基金supported by the National Key Project for Basic Research of China (973 Project) (No. 2005CB221400)
文摘Nickel and potassium co-modified β-Mo2C catalysts were prepared and used for CO hydrogenation reaction. The major products over β-Mo2C were C1-C4 hydrocarbons, only few alcohols were obtained. Addition of potassium resulted in remarkable selectivity shift from hydrocarbons to alcohols at the expense of CO conversion over β-Mo2C. Moreover, it was found that potassium enhanced the ability of chain propagation with a higher C2＋OH production. Modified by nickel,β-Mo2C showed a relatively high CO conversion, however, the products were similar to those of pure β-Mo2C. When co-modified by nickel and potassium,β-Mo2C exhibited high activity and selectivity towards mixed alcohols synthesis, and also the whole chain propagation to produce alcohols especially for the stage of C1 OH to C2OH was remarkably enhanced. It was concluded that the Ni and K had, to some extent, synergistic effect on CO conversion.
基金financially supported by the National Science Foundation of China (21671132)Shanghai Science and Technology Committee(16dz1207200)the Youth Innovation Promotion Association CAS(2015231)
文摘MnOx-promoted Ni-based catalyst supported by ZnO was developed to selectively hydrogenate glucose into polyols in water at 523 K with a yield of 64.9%. Using glucose, sorbitol, glycerol and LA as the rawmaterials, the roles of nickel, ZnO and MnOx were investigated. The results show that nickel provided a new pathway of glucose to sorbitol and played an important role in the hydrogenation of C3 intermediates to 1,2-propanediol(1,2-PDO). The high yield of 1, 2-PDO was attributed to effective C–C bond cleavage performance of ZnO support promoted by MnOx. ZnO and MnOx contribute to the conversion of glycerol to lactic acid(LA) and LA to 1, 2-PDO, respectively. A concise pathway for hydrogenation of glucose over Ni-based catalyst was proposed.
基金supported by grants from the Guangdong Provincial Science and Technology Plan Project(2016B020201002)the Science and Technology Research Project of Beijing Forestry University(2018WS01)+2 种基金the Research and Development Project of Beijing Forestry University(2016BLPX13)the National Natural Science Foundation of China(31700581)the Key Project of the National Forestry Bureau(2012–06)。
文摘Chinese fir(Cunninghamia lanceolata(Lamb.)Hook),a fast-growing and economically important timber tree species in China,is widely used in construction,furniture,and paper manufacture but has a long breeding cycle.Chemical mutagens,such as ethyl methane sulfonate(EMS)and sodium azide(SA),are widely used in crops such as rice,wheat,cotton,soybean and sugarcane but their utility for tree breeding is unknown.In this study we examined the effects of EMS and S A on Chinese fir seed germination and growth.Chinese fir seeds were treated with the two chemical mutagens;were planted in Jiangle County,Fujian Province,China;and their heights were measured from 2011 to2017.The concentrations and durations of treatment with the two chemical mutagens were significantly associated with the Chinese fir seedling and mortality rates,as well as with the heights of trees from the seedling stage to 3 years old.We also generated 127 mutants with abnormal branches and reproductive growth.We report here the effects of two chemical mutagens on Chinese fir breeding;our data will contribute to knowledge of the utility of EMS and SA in forestry.
文摘Based on the difference of hydroxy group configuration on the special adsorption and coordination of phosphate on the dispersed α-Fe2O3 nanodisks with diameter of 150-200 nm different planes of α-Fe2O3 nanoparticles, using （001） plane of α-Fe2O3, well-crystallized and well and thickness of 40-80 nm were synthesized via a hydrotherrnal method. The magnetic properties of synthesized nanodisks were investigated. It was found that the nanodisks possessed a saturation magnetization （Ms） of 0.38 emu/g, a rernanent magnetization （Mr） of 0.031 ernu/g and a coercivity of 452.91 Oe at room temperature. The Mr and coercivity of synthesized α-Fe2O3 nanodisks are higher and the Ms is lower than those of other previously reported α-Fe2O3 nanostructures.
基金supported by the Key Project of Chinese National Programs for Fundamental Research and Development(973 Program-2005CB221400)
文摘Fe modified and un-modified K/Mo2C were prepared and investigated as catalysts for CO hydrogenation reaction. Compared with K/Mo2C catalyst, the addition of Fe increased the production of alcohols, especially the C2＋OH. Meanwhile, considerable amounts of C5＋ hydrocar- bons and C2= -C4= were formed, whereas methane selectivity greatly decreased. Also, the activity and selectivity of the catalyst were readily affected by the reaction pressure and temperature employed. According to the XPS results, Mo4＋ might be responsible for the production of alcohols, whereas the low valence state of Mo species such as Mo^0 and/or Mo^2＋ might be account for the high activity and selectivity toward hydrocarbons.
