Acetylene is produced from the reaction between calcium carbide(CaC_(2))and water,while the production of CaC_(2) generates significant amount of carbon dioxide not only because it is an energy-intensive process but a...Acetylene is produced from the reaction between calcium carbide(CaC_(2))and water,while the production of CaC_(2) generates significant amount of carbon dioxide not only because it is an energy-intensive process but also the raw material for CaC_(2) synthesis is from coal.Here,a comprehensive biomass-to-acetylene process was constructed that integrated several units including biomass pyrolysis,oxygen-thermal CaC_(2) fabrication and calcium looping.For comparison,a coal-to-acetylene process was also established by using coal as feedstock.The carbon efficiency,energy efficiency and environmental impacts of the bio-based calcium carbide acetylene(BCCA)and coal-based calcium carbide acetylene(CCCA)processes were systematically analyzed.Moreover,the environmental impacts were further evaluated by applying thermal integration at system level and energy substitution in CaC_(2) furnace.Even though the BCCA process showed lower carbon efficiency and energy efficiency than that of the CCCA process,life cycle assessment demonstrated the BCCA(1.873 kgCO_(2eq) kg-prod^(-1))a lower carbon footprint process which is 0.366 kgCO_(2eq) kg-prod^(-1) lower compared to the CCCA process.With sustainable energy(biomass power)substitution in CaC_(2) furnace,an even lower GWP value of 1.377 kgCO_(2eq) kg-prod^(-1) can be achieved in BCCA process.This work performed a systematic analysis on integrating biomass into industrial acetylene production,and revealed the positive role of biomass as raw material(carbon)and energy supplier.展开更多
A series of model catalysts were obtained by treating commercial fresh and spent catalysts unloaded from the factory with different methods, including green oil dipping, extraction and high-temperature regeneration;fi...A series of model catalysts were obtained by treating commercial fresh and spent catalysts unloaded from the factory with different methods, including green oil dipping, extraction and high-temperature regeneration;finally, the deactivation behavior of the commercial catalyst for acetylene hydrogenation were studied. The influence of various possible deactivation factors on the catalytic performance was elucidated via detailed structural characterization, surface composition analysis, and activity evaluation.The results showed that green oil, carbon deposit and sintering of active metal were the main reasons for deactivation, among which green oil and carbon deposit led to rapid deactivation, while the activity could be recovered after regeneration by high-temperature calcination. The sintering of active metal components was attributed to the high-temperature regeneration in hydrothermal conditions, which was slow but irreversible and accounted for permanent deactivation. Thus, optimizing the regeneration is expected to extend the service life of the commercial catalyst.展开更多
The reactions of [Bt3NH][μ-CO)(μ-RS)Fe2(CO)6] (1a-d) (R=nPr,nBu,tBu, Ph) with p-MeC6H4C=CPh or m-NO2C6H4C=CPh were studied and products of the vinyl type (μ-σ,π-p-MeC6H4C=CHPh)(μ-RS)Fe2(CO)6 (2) and (μ-σ,π-ph...The reactions of [Bt3NH][μ-CO)(μ-RS)Fe2(CO)6] (1a-d) (R=nPr,nBu,tBu, Ph) with p-MeC6H4C=CPh or m-NO2C6H4C=CPh were studied and products of the vinyl type (μ-σ,π-p-MeC6H4C=CHPh)(μ-RS)Fe2(CO)6 (2) and (μ-σ,π-phC=CHC6H4Me-p) (μ-RS)Fe2(CO)6 (3) (R=nPr, nBu, tBu, Ph) were obtained. While the structures of all the compounds 2a-d and 3a-d were characterized by elemental analysis, IR,1H NMR and MS spectroscopies, the single-crystal structure of 2c(R=tBu) was determined by X-ray diffraction method. The X-ray dim-action result of 2c showed that the substituted vinyl ligand p-MeC6H4C=CHPh bridges the two uon centers, being σ-bonded to one metal through the olefinic carbon attached to p-MeC6H44 group, while π-bonded to the other via olefinic linkage; the Fe2(CO)6 and proton units are in a cis fashion and the tBu group is bonded to sulfur atom through an e-type of bond.展开更多
Rational design of catalytic sites to activate the C≡C bond is of paramount importance to advance acetylene hydrochlorination. Herein, Cu sites with electron-rich and electron-deficient states were constructed by con...Rational design of catalytic sites to activate the C≡C bond is of paramount importance to advance acetylene hydrochlorination. Herein, Cu sites with electron-rich and electron-deficient states were constructed by controlling the impregnation solutions. The π electrons flowing from acetylene to Cu site are facilitated over the electron-deficient Cu sites, achieving high activation of C≡C bond. The contradiction between the increased activation of acetylene required for enhanced catalytic activity and the resistance of Cu site to reduction by acetylene required for maintaining catalytic stability can be balanced by establishing strong interactions of Cu site with pyrrolic-N species. The catalytic activity displays a volcano shape scaling relationship as a function of Cu particle size. Tribasic copper chloride is concomitantly generated with the construction of electron-deficient Cu sites. The H–Cl bond of HCl can be activated over the tribasic copper chloride, accelerating the surface reaction of vinyl chloride production. This strategy of inducing electron deficiency provides new insight into the rational design of catalysts for the synthesis of vinyl chloride with a high catalytic performance.展开更多
In this work,DFT calculations were used firstly to simulate the nitrogen coordinated metal single-atom catalysts(M-N_(x)SACs,M=Hg,Cu,Au,and Ru) to predict their catalytic activities in acetylene hydrochlorination.The ...In this work,DFT calculations were used firstly to simulate the nitrogen coordinated metal single-atom catalysts(M-N_(x)SACs,M=Hg,Cu,Au,and Ru) to predict their catalytic activities in acetylene hydrochlorination.The DFT results showed that Ru-N_(x)SACs had the best catalytic performance among the four catalysts,and Ru-N_(x)SACs could effectively inhibit the reduction of ruthenium cation.To verify the DFT results,Ru-N_(x)SACs were fabricated by pyrolyzing MOFs in-situ spatially confined metal precursors.The N coordination environment could be controlled by changing the pyrolysis temperature.Catalytic performance tests indicated that low N coordination number(Ru-N_(2),Ru-N_(3))exhibited excellent catalytic activity and stability compared to RuCl_(3)catalyst.DFT calculations further revealed that Ru-N_(2)and Ru-N_(3)had a tendency to activate HCl at the first step of reaction,whereas Ru-N4tended to activate C_(2)H_(2).These findings will serve as a reference for the design and control of metal active sites.展开更多
This work aims to solve the problems of low reaction activity of Cu-based catalysts and agglomeration of active centers in acetylene hydrochlorination.Cu-based catalysts supported by NAP co-doped activated carbon(AC)w...This work aims to solve the problems of low reaction activity of Cu-based catalysts and agglomeration of active centers in acetylene hydrochlorination.Cu-based catalysts supported by NAP co-doped activated carbon(AC)with different content(mCu-xNP/AC)were manufactured and applied in the acetylene hydrochlorination reaction.It was found that the doping of carriers N and P induced the transformation of Cu^(2+)to Cu^(+),and the catalytic activity was markedly improved.Under the optimal reaction temperature of 220℃,the gas hourly space velocity(GHSV)of C_(2)H_(2)was 90 h^(-1)and V_(HCl):V_(C_(2)H_(2))was 1.15.The initial activity of the 5%Cu-30 NP/AC catalyst reached 95.59%.Through some characterization methods showed the addition of N and P improved the dispersion of Cu in carbon,which increased the ratio of Cu^+/Cu^(2+).The measurement results confirmed that the chemisorption capacity of mCu-xNP/AC for C_(2)H_(2)decreased slightly,and the chemisorption capacity for HCl increased significantly,which was the reason for the increased activity of the catalyst.The conclusion provides a reference for the development of acetylene hydrochlorination Cu catalyst.展开更多
This article presents simulation results on the effects of neutral gas flow for nanoparticle transport in atmospheric-pressure,radio-frequency,capacitively-coupled,and acetylene discharge.The acetylene gas is set to f...This article presents simulation results on the effects of neutral gas flow for nanoparticle transport in atmospheric-pressure,radio-frequency,capacitively-coupled,and acetylene discharge.The acetylene gas is set to flow into the chamber from the upper showerhead electrode.The internal energy of the gas medium therein is transferred into kinetic energy so the gas advection can be triggered.This is represented by the pressure volume work term of the gas energy converse equation.The gas advection leads to the gas temperature sink at the gas inlet,hence a large gas temperature gradient is formed.The thermophoresis relies on the gas temperature gradient,and causes the profile of nanoparticle density to vary from a double-peak structure to a single-peak one.The gas advection influences the properties of electron density and temperature as well and causes the drift-ambipolar mode profile of electron density asymmetric.In the bulk region,i.e.away from the inlet,the gas advection is more like one isovolumetric compression,which slightly increases the temperature of the gas medium at consuming its kinetic energy.展开更多
New hyperbranched poly(aryleneethynylene)s containing carbazole moieties are synthesized in high yields (up to 87%) by polycyclotrimerization of 3,6-bis(4-ethynylphenyl)-9-octylcarbazole and its copolymerization...New hyperbranched poly(aryleneethynylene)s containing carbazole moieties are synthesized in high yields (up to 87%) by polycyclotrimerization of 3,6-bis(4-ethynylphenyl)-9-octylcarbazole and its copolymerization with 1-octyne catalyzed by CpCo(CO)2 in THF. The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, UV, photoluminescence, and cyclic voltammetry analyses. All the polymers are soluble in common organic solvents and show outstanding thermal stability (≥ 430℃). They graphitize in high yields (up to 79%) when pyrolyzed at 800℃. Upon photoexcitation, the polymers emit a strong deep blue light of ca. 400 nm with quantum yields larger than 60%.展开更多
A laboratory incubation experiment was conducted to investigate nitrous oxide(N 2O) emission and reduction in a paddy soil(Stagnic Anthrosol) response to the pretreatment of water regime. The paddy soil was maintaine...A laboratory incubation experiment was conducted to investigate nitrous oxide(N 2O) emission and reduction in a paddy soil(Stagnic Anthrosol) response to the pretreatment of water regime. The paddy soil was maintained under either air dried(sample D) or submerged(sample F) conditions for 110 d before the soil was adjusted into soil moisture of 20%, 40%, 60%, 80% and 100% water holding capacity(WHC) respectively, and then incubated with or without 10%(v/v) acetylene for 138 h at 25℃. At lower soil water content (≤60% WHC), N 2O emission from the sample F was 2 29 times higher than that from the sample D( P <0 01). While, N 2O emission from the sample F was only 29 and 14 percent of that from the sample D at the soil moisture of 80% and 100% WHC, respectively( P <0 01). The maximal N 2O emissions observed at soil moisture of 80% WHC were about 24 and 186 times higher than the minima obtained at the soil moisture of 20% WHC for the sample F and D, respectively. But at the soil moisture of 80% and 100% WHC, N 2O emission from the sample F with acetylene(F+ACE) was comparable to that of the sample D with acetylene (D+ACE). The results showed that the F sample produced N 2O ability in denitrification was similar to the sample D, however, the sample F was in the better reduction of N 2O to N 2 than the sample D even after the soil moisture was adjusted into the same level of 80% or 100% WHC. Therefore, the pretreatment of water regime influenced the strength and product composition of denitrification and N 2O emission from the paddy soil.展开更多
Commercial production of vinyl chloride from acetylene relies on the use of HgCla as the catalyst, which has caused severe environmental problem and threats to human health because of its toxicity. Therefore, it is vi...Commercial production of vinyl chloride from acetylene relies on the use of HgCla as the catalyst, which has caused severe environmental problem and threats to human health because of its toxicity. Therefore, it is vital to explore alternative catalysts without mercury. We report here that N-doped carbon can catalyze directly transformation of acetylene to vinyl chloride. Particularly, N-doped high surface area mesoporous carbon exhibits a rather high activity with the acetylene conversion reaching 77% and vinyl chloride selectivity above 98% at a space velocity of 1.0 mL.min-l.g-1 and 200 ~C. It delivers a stable performa℃nce within a test period of 100h and no obvious deactivation is observed, demonstrating potentials to substitute the notoriously toxic mercuric chloride catalyst.展开更多
In the process of dimerization of acetylene to produce monovinylacetylene (MVA),the loss of active component CuCl in the Nieuwland catalyst due to the formation of a dark red precipitate was investigated.The formula...In the process of dimerization of acetylene to produce monovinylacetylene (MVA),the loss of active component CuCl in the Nieuwland catalyst due to the formation of a dark red precipitate was investigated.The formula of the precipitate was CuCl·2C2H2·1/5NH 3,and it was presumed to be formed by the combination of NH 3,C2H2 and [Cu]-acetylene π-complex,which was an intermediate in the dimerization reaction.The addition of hydrochloric acid into the catalyst can reduce the formation of precipitate,whereas excessive H+ is unfavorable to the dimerization reaction of acetylene.To balance between high acetylene conversion and low loss rate of CuCl,the optimum mass percentage of HCl in the added hydrochloric acid was determined.The result showed the optimum mass percentage of HCl decreased from 5.0% to 3.2% when the space velocity of acetylene was from 140 h-1 to 360 h-1.The result in this work also indicated the pH of the Nieuwland catalyst should be kept in the range of 5.80-5.97 during the reaction process,which was good for both catalyst life and acetylene conversion.展开更多
Ni/Si O_2 and bimetallic Ni_xGa/SiO_2 catalysts with different Ni/Ga atomic ratios(x = 10~2) were investigated for the selective hydrogenation of acetylene.It was found that Ni_xGa/SiO_2 showed higher selectivity to ...Ni/Si O_2 and bimetallic Ni_xGa/SiO_2 catalysts with different Ni/Ga atomic ratios(x = 10~2) were investigated for the selective hydrogenation of acetylene.It was found that Ni_xGa/SiO_2 showed higher selectivity to ethylene than Ni/Si O_2.This is attributed to the formation Ni-Ga alloy and Ni3 Ga intermetallic compound(IMC) where there was a charge transfer from Ga to Ni,which is favorable for reducing the adsorption strength and amount of ethylene on Ni atoms.As a result,the over-hydrogenation,the C–C bond hydrogenolysis and the polymerization were suppressed,and subsequently the selectivity to ethylene was enhanced.With the decrease of Ni/Ga atomic ratio,the activity and stability of the Ni_xGa/SiO_2 catalysts increased first and then decreased,while the ethylene selectivity tended to increase.Ni_5 Ga/SiO_2 exhibited the best performance.Under the conditions of 180 °C,0.1 MPa,and a reactant(1.0 vol% acetylene,5.0 vol% H_2 and 94 vol% N_2) with the space velocity of 36,000 m L h^(-1) g^(-1),the acetylene conversion maintained at 100% on Ni_5 Ga/SiO_2 during 120 h time on stream and the selectivity to ethylene was 75%~81%after reaction for 68 h.It was also found that the formation of Ni-Ga alloy and Ni_3 Ga IMC suppressed the incorporation of carbon to form NiCx,subsequently enhancing the catalyst stability.Additionally,with increasing the Ga content,the catalyst acid amount and strength tended to increase,which promoted the polymerization and carbon deposition and so the catalyst deactivation.展开更多
The chemical thermodynamic equilibrium of acetylene production by coal pyrolysis in hydrogen plasma was studied. The thermodynamic equilibrium is obtained by using the method of free energy. Calculated results show th...The chemical thermodynamic equilibrium of acetylene production by coal pyrolysis in hydrogen plasma was studied. The thermodynamic equilibrium is obtained by using the method of free energy. Calculated results show that the hydrogen concentration in the equilibrium system is very important for the acetylene production by coal conversion and the energy consumption for the production of acetylene per-kilogram strongly depends on the hydrogen concentration and the temperature.展开更多
A novel chiral methylpropargyl ester containing azobenzene moiety(S)-(-)-3-methyl-3-{4-[4-(n-octyloxy)phenylazophenyl]carbonyl}oxy-1-propyne 3(C25H30N2O3,Mr = 406.51) was synthesized and characterized by IR,NM...A novel chiral methylpropargyl ester containing azobenzene moiety(S)-(-)-3-methyl-3-{4-[4-(n-octyloxy)phenylazophenyl]carbonyl}oxy-1-propyne 3(C25H30N2O3,Mr = 406.51) was synthesized and characterized by IR,NMR and single-crystal X-ray diffraction.The crystal is of monoclinic system,space group P21 with a=6.7610(17),b=7.675(2),c=22.749(7),β=97.613(6)°,V=1170.1(6)3,Z=2,Dc=1.154,F(000)=436,μ=0.076 mm-1,R=0.0544 and wR=0.1569 for 2444 observed reflections with Ⅰ〉2σ(Ⅰ).Structure analysis proved that the azobenzene presents a trans form, and intermolecular hydrogen bonds yield a 3D framework. The ehiral acetylene carrying azobenzene moieties can be a potential alternative nonlinear optical, helical polymer, and liquid crystalline material.展开更多
The concentrations of nitrous oxide varies between 57 and 329 nmol/dm3, saturation is 674%~4 134% in the Zhujiang River Estuary. This suggests that the area is an emissive source of nitrous oxide. The acetylene inhib...The concentrations of nitrous oxide varies between 57 and 329 nmol/dm3, saturation is 674%~4 134% in the Zhujiang River Estuary. This suggests that the area is an emissive source of nitrous oxide. The acetylene inhibition technique is employed to evaluate the rates of nitrification, denitrification and nitrate reduction by bacterial activities in the sediments at three sites. The average of nitrification, denitrification and nitrate reduction rates ranges from 0.32 to 2.43, 0.03 to 0.84 and 4.17 to 13.06 mmol/(m2·h), respectively. The ver- tical profiles of the sediments show that the nitrification and denitrification processes mainly take place in the depth from 0 to 4 cm and depend on regional conditions. The rates of nitrification, denitrification and nitrate reduction are dominated by Eh, nitrate and ammoni- um concentrations in sediments and DO in overlay water. There is a coupling between nitrification and denitrification.展开更多
Ce-A12O3 catalysts prepared by co-precipitation are investigated both in NO oxidation by 02 and in selective catalytic reduction of NO by C2H2 (C2H2-SCR). It is found that C2H2-SCR is initiated and controlled by NO ...Ce-A12O3 catalysts prepared by co-precipitation are investigated both in NO oxidation by 02 and in selective catalytic reduction of NO by C2H2 (C2H2-SCR). It is found that C2H2-SCR is initiated and controlled by NO oxidation to NO2 over A12O3. Ce loading on A12O3 is almost inactive for NO oxidation below 350℃, since NO2 strongly adsorbs on cerium oxide, leading to the active sites being blocked, which was characterized by temperature-programmed desorption of NO and NO2 and Fourier transform infrared spectroscopy after NO+O2 coadsorption over the samples. However, in the case of C2H2-SCR, Ce loading on A1203 significantly improves the reaction by accelerating the NO oxidation step in the temperature range of 250-450℃, since the nitrate species produced by NO2 adsorption is an active intermediate required by C2H2-SCR.展开更多
Cost effective separation of acetylene(C_2H_2)and ethylene(C_2H_4)is of key importance to obtain essential chemical raw materials for polymer industry.Due to the low compression limit of C_2H_2,there is an urgent dema...Cost effective separation of acetylene(C_2H_2)and ethylene(C_2H_4)is of key importance to obtain essential chemical raw materials for polymer industry.Due to the low compression limit of C_2H_2,there is an urgent demand to develop suitable materials for efficiently separating the two gases under ambient conditions.In this paper,we provided a high-throughput screening strategy to study porous metal-organic frameworks(MOFs)containing open metal sites(OMS)for C_2H_2/C_2H_4 separation,followed by a rational design of novel MOFs in-silico.A set of accurate force fields was established from ab initio calculations to describe the critical role of OMS towards guest molecules.From a large-scale computational screening of 916 experimental Cu-paddlewheel-based MOFs,three materials were identified with excellent separation performance.The structure-performance relationships revealed that the optimal materials should have the largest cavity diameter around 5-10?and pore volume in-between 0.3-1.0 cm^3 g^(-1).Based on the systematic screening study result,three novel MOFs were further designed with the incorporation of fluorine functional group.The results showed that Cu-OMS and the-F group on the aromatic rings close to Cu sites could generate a synergistic effect on the preferential adsorption of C_2H_2 over C_2H_4,leading to a remarkable improvement of C_2H_2 separation performance of the materials.The findings could provide insight for future experimental design and synthesis of high-performance nanostructured materials for C_2H_2/C_2H_4 separation.展开更多
A new preparation method was proposed to deposit amorphous alloys alloys containing NiPand metallic metallic additives such as Fe.Co. and Cu.The different effects of metallic additive onstructure and catalytic ...A new preparation method was proposed to deposit amorphous alloys alloys containing NiPand metallic metallic additives such as Fe.Co. and Cu.The different effects of metallic additive onstructure and catalytic properties of supported amorphous NiMPB/SiO2 (M=Fe, Co. Cu) cafalysts were observed,and the improvement of catalytic activity due to heating pretreatment in hydrogenwas found.展开更多
Methane coupling in microwave plasma under atmospheric pressure has been investigated.The effects of molar ratio n(CH4)/n(H2),flow rate and microwave power on the reaction have been studied.(1)With the decrease ...Methane coupling in microwave plasma under atmospheric pressure has been investigated.The effects of molar ratio n(CH4)/n(H2),flow rate and microwave power on the reaction have been studied.(1)With the decrease of n(CH4)/n(H2)ratio,methane conversion,C2 hydrocarbon yield,energy yield and space-time yield of acetylene increased,but the yield of carbon deposit decreased.(2)With the increase of microwave power,energy yield of acetylene decreased,but space-time yield of acetylene increased.(3)With the increase of flow rate,energy yield and space-time yield of acetylene increased first and then decreased.Finally,under the reaction conditions of CH4 flow rate of 700 mL/min,n(CH4)/n(H2)ratio of 1/4 and microwave power of 400 W,the energy yield and space-time yield of acetylene could reach 0.337 mmol/kJ and 12.3 mol/(s m3),respectively.The reaction mechanism of methane coupling in microwave plasma has been investigated based on the thermodynamics of chemical reaction.Interestingly,the acetylene yield of methane coupling in microwave plasma was much higher than the maximum thermodynamic yield of acetylene.This phenomenon was tentatively explained from non-expansion work in the microwave plasma system.展开更多
基金the National Natural Science Foundation of China(21978128,91934302)the State Key Laboratory of Materials-oriented Chemical Engineering(ZK202006)is acknowledged.
文摘Acetylene is produced from the reaction between calcium carbide(CaC_(2))and water,while the production of CaC_(2) generates significant amount of carbon dioxide not only because it is an energy-intensive process but also the raw material for CaC_(2) synthesis is from coal.Here,a comprehensive biomass-to-acetylene process was constructed that integrated several units including biomass pyrolysis,oxygen-thermal CaC_(2) fabrication and calcium looping.For comparison,a coal-to-acetylene process was also established by using coal as feedstock.The carbon efficiency,energy efficiency and environmental impacts of the bio-based calcium carbide acetylene(BCCA)and coal-based calcium carbide acetylene(CCCA)processes were systematically analyzed.Moreover,the environmental impacts were further evaluated by applying thermal integration at system level and energy substitution in CaC_(2) furnace.Even though the BCCA process showed lower carbon efficiency and energy efficiency than that of the CCCA process,life cycle assessment demonstrated the BCCA(1.873 kgCO_(2eq) kg-prod^(-1))a lower carbon footprint process which is 0.366 kgCO_(2eq) kg-prod^(-1) lower compared to the CCCA process.With sustainable energy(biomass power)substitution in CaC_(2) furnace,an even lower GWP value of 1.377 kgCO_(2eq) kg-prod^(-1) can be achieved in BCCA process.This work performed a systematic analysis on integrating biomass into industrial acetylene production,and revealed the positive role of biomass as raw material(carbon)and energy supplier.
基金the financial support from the Sinopec Catalyst Co.Ltd.,China。
文摘A series of model catalysts were obtained by treating commercial fresh and spent catalysts unloaded from the factory with different methods, including green oil dipping, extraction and high-temperature regeneration;finally, the deactivation behavior of the commercial catalyst for acetylene hydrogenation were studied. The influence of various possible deactivation factors on the catalytic performance was elucidated via detailed structural characterization, surface composition analysis, and activity evaluation.The results showed that green oil, carbon deposit and sintering of active metal were the main reasons for deactivation, among which green oil and carbon deposit led to rapid deactivation, while the activity could be recovered after regeneration by high-temperature calcination. The sintering of active metal components was attributed to the high-temperature regeneration in hydrothermal conditions, which was slow but irreversible and accounted for permanent deactivation. Thus, optimizing the regeneration is expected to extend the service life of the commercial catalyst.
基金supported by the National Natural Science Foundation of China.
文摘The reactions of [Bt3NH][μ-CO)(μ-RS)Fe2(CO)6] (1a-d) (R=nPr,nBu,tBu, Ph) with p-MeC6H4C=CPh or m-NO2C6H4C=CPh were studied and products of the vinyl type (μ-σ,π-p-MeC6H4C=CHPh)(μ-RS)Fe2(CO)6 (2) and (μ-σ,π-phC=CHC6H4Me-p) (μ-RS)Fe2(CO)6 (3) (R=nPr, nBu, tBu, Ph) were obtained. While the structures of all the compounds 2a-d and 3a-d were characterized by elemental analysis, IR,1H NMR and MS spectroscopies, the single-crystal structure of 2c(R=tBu) was determined by X-ray diffraction method. The X-ray dim-action result of 2c showed that the substituted vinyl ligand p-MeC6H4C=CHPh bridges the two uon centers, being σ-bonded to one metal through the olefinic carbon attached to p-MeC6H44 group, while π-bonded to the other via olefinic linkage; the Fe2(CO)6 and proton units are in a cis fashion and the tBu group is bonded to sulfur atom through an e-type of bond.
基金Financial support from the National Natural Science Foundation of China (NSFCgrant No.U20A20119,21606199,22078302,52070035)+3 种基金the Science and Technology Department of Zhejiang Province (LGG20B060004)the China Postdoctoral Science Foundation (2020M671791)the Jilin Province Scientific and the Technological Planning Project of China (No.20200403001SF)the National Key Research and Development Program of China (2021YFA1501800,2021YFA1501801,2021YFA1501802)。
文摘Rational design of catalytic sites to activate the C≡C bond is of paramount importance to advance acetylene hydrochlorination. Herein, Cu sites with electron-rich and electron-deficient states were constructed by controlling the impregnation solutions. The π electrons flowing from acetylene to Cu site are facilitated over the electron-deficient Cu sites, achieving high activation of C≡C bond. The contradiction between the increased activation of acetylene required for enhanced catalytic activity and the resistance of Cu site to reduction by acetylene required for maintaining catalytic stability can be balanced by establishing strong interactions of Cu site with pyrrolic-N species. The catalytic activity displays a volcano shape scaling relationship as a function of Cu particle size. Tribasic copper chloride is concomitantly generated with the construction of electron-deficient Cu sites. The H–Cl bond of HCl can be activated over the tribasic copper chloride, accelerating the surface reaction of vinyl chloride production. This strategy of inducing electron deficiency provides new insight into the rational design of catalysts for the synthesis of vinyl chloride with a high catalytic performance.
基金supported by the National Natural Science Foundation of China (NSFC,22172082,21978137,22102074,and 21878162)Natural Science Foundation of Tianjin (20JCZDJC00770)+1 种基金Postdoctoral Research Foundation of China (2021M701776)NCC Fund (NCC2020FH05)。
文摘In this work,DFT calculations were used firstly to simulate the nitrogen coordinated metal single-atom catalysts(M-N_(x)SACs,M=Hg,Cu,Au,and Ru) to predict their catalytic activities in acetylene hydrochlorination.The DFT results showed that Ru-N_(x)SACs had the best catalytic performance among the four catalysts,and Ru-N_(x)SACs could effectively inhibit the reduction of ruthenium cation.To verify the DFT results,Ru-N_(x)SACs were fabricated by pyrolyzing MOFs in-situ spatially confined metal precursors.The N coordination environment could be controlled by changing the pyrolysis temperature.Catalytic performance tests indicated that low N coordination number(Ru-N_(2),Ru-N_(3))exhibited excellent catalytic activity and stability compared to RuCl_(3)catalyst.DFT calculations further revealed that Ru-N_(2)and Ru-N_(3)had a tendency to activate HCl at the first step of reaction,whereas Ru-N4tended to activate C_(2)H_(2).These findings will serve as a reference for the design and control of metal active sites.
基金supported by the Taishan Scholars Program of Shandong Province(tsqn202103051)the Project of Scientific Research in Shihezi University(CXFZ202205)。
文摘This work aims to solve the problems of low reaction activity of Cu-based catalysts and agglomeration of active centers in acetylene hydrochlorination.Cu-based catalysts supported by NAP co-doped activated carbon(AC)with different content(mCu-xNP/AC)were manufactured and applied in the acetylene hydrochlorination reaction.It was found that the doping of carriers N and P induced the transformation of Cu^(2+)to Cu^(+),and the catalytic activity was markedly improved.Under the optimal reaction temperature of 220℃,the gas hourly space velocity(GHSV)of C_(2)H_(2)was 90 h^(-1)and V_(HCl):V_(C_(2)H_(2))was 1.15.The initial activity of the 5%Cu-30 NP/AC catalyst reached 95.59%.Through some characterization methods showed the addition of N and P improved the dispersion of Cu in carbon,which increased the ratio of Cu^+/Cu^(2+).The measurement results confirmed that the chemisorption capacity of mCu-xNP/AC for C_(2)H_(2)decreased slightly,and the chemisorption capacity for HCl increased significantly,which was the reason for the increased activity of the catalyst.The conclusion provides a reference for the development of acetylene hydrochlorination Cu catalyst.
基金supported by National Natural Science Foundation of China(Nos.11805107 and 12275039)the Fundamental Research Funds in Heilongjiang Provincial Universities of China(No.135509124)the Graduate Innovation Foundation of Qiqihar University(No.YJSCX2022014)。
文摘This article presents simulation results on the effects of neutral gas flow for nanoparticle transport in atmospheric-pressure,radio-frequency,capacitively-coupled,and acetylene discharge.The acetylene gas is set to flow into the chamber from the upper showerhead electrode.The internal energy of the gas medium therein is transferred into kinetic energy so the gas advection can be triggered.This is represented by the pressure volume work term of the gas energy converse equation.The gas advection leads to the gas temperature sink at the gas inlet,hence a large gas temperature gradient is formed.The thermophoresis relies on the gas temperature gradient,and causes the profile of nanoparticle density to vary from a double-peak structure to a single-peak one.The gas advection influences the properties of electron density and temperature as well and causes the drift-ambipolar mode profile of electron density asymmetric.In the bulk region,i.e.away from the inlet,the gas advection is more like one isovolumetric compression,which slightly increases the temperature of the gas medium at consuming its kinetic energy.
基金This project was financially supported by National Natural Science Foundation of China(No.50473034).
文摘New hyperbranched poly(aryleneethynylene)s containing carbazole moieties are synthesized in high yields (up to 87%) by polycyclotrimerization of 3,6-bis(4-ethynylphenyl)-9-octylcarbazole and its copolymerization with 1-octyne catalyzed by CpCo(CO)2 in THF. The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, UV, photoluminescence, and cyclic voltammetry analyses. All the polymers are soluble in common organic solvents and show outstanding thermal stability (≥ 430℃). They graphitize in high yields (up to 79%) when pyrolyzed at 800℃. Upon photoexcitation, the polymers emit a strong deep blue light of ca. 400 nm with quantum yields larger than 60%.
文摘A laboratory incubation experiment was conducted to investigate nitrous oxide(N 2O) emission and reduction in a paddy soil(Stagnic Anthrosol) response to the pretreatment of water regime. The paddy soil was maintained under either air dried(sample D) or submerged(sample F) conditions for 110 d before the soil was adjusted into soil moisture of 20%, 40%, 60%, 80% and 100% water holding capacity(WHC) respectively, and then incubated with or without 10%(v/v) acetylene for 138 h at 25℃. At lower soil water content (≤60% WHC), N 2O emission from the sample F was 2 29 times higher than that from the sample D( P <0 01). While, N 2O emission from the sample F was only 29 and 14 percent of that from the sample D at the soil moisture of 80% and 100% WHC, respectively( P <0 01). The maximal N 2O emissions observed at soil moisture of 80% WHC were about 24 and 186 times higher than the minima obtained at the soil moisture of 20% WHC for the sample F and D, respectively. But at the soil moisture of 80% and 100% WHC, N 2O emission from the sample F with acetylene(F+ACE) was comparable to that of the sample D with acetylene (D+ACE). The results showed that the F sample produced N 2O ability in denitrification was similar to the sample D, however, the sample F was in the better reduction of N 2O to N 2 than the sample D even after the soil moisture was adjusted into the same level of 80% or 100% WHC. Therefore, the pretreatment of water regime influenced the strength and product composition of denitrification and N 2O emission from the paddy soil.
基金supported by the Natural Science Foundation of China(No.11079005 and 21033009)the Ministry of Science and Technology of China(2011CBA00503 and 2012CB720302)
文摘Commercial production of vinyl chloride from acetylene relies on the use of HgCla as the catalyst, which has caused severe environmental problem and threats to human health because of its toxicity. Therefore, it is vital to explore alternative catalysts without mercury. We report here that N-doped carbon can catalyze directly transformation of acetylene to vinyl chloride. Particularly, N-doped high surface area mesoporous carbon exhibits a rather high activity with the acetylene conversion reaching 77% and vinyl chloride selectivity above 98% at a space velocity of 1.0 mL.min-l.g-1 and 200 ~C. It delivers a stable performa℃nce within a test period of 100h and no obvious deactivation is observed, demonstrating potentials to substitute the notoriously toxic mercuric chloride catalyst.
基金supported by the National Basic Research Program of China (No. 2009CB219901)
文摘In the process of dimerization of acetylene to produce monovinylacetylene (MVA),the loss of active component CuCl in the Nieuwland catalyst due to the formation of a dark red precipitate was investigated.The formula of the precipitate was CuCl·2C2H2·1/5NH 3,and it was presumed to be formed by the combination of NH 3,C2H2 and [Cu]-acetylene π-complex,which was an intermediate in the dimerization reaction.The addition of hydrochloric acid into the catalyst can reduce the formation of precipitate,whereas excessive H+ is unfavorable to the dimerization reaction of acetylene.To balance between high acetylene conversion and low loss rate of CuCl,the optimum mass percentage of HCl in the added hydrochloric acid was determined.The result showed the optimum mass percentage of HCl decreased from 5.0% to 3.2% when the space velocity of acetylene was from 140 h-1 to 360 h-1.The result in this work also indicated the pH of the Nieuwland catalyst should be kept in the range of 5.80-5.97 during the reaction process,which was good for both catalyst life and acetylene conversion.
基金supported by the National Natural Science Foundation of China (21576193)
文摘Ni/Si O_2 and bimetallic Ni_xGa/SiO_2 catalysts with different Ni/Ga atomic ratios(x = 10~2) were investigated for the selective hydrogenation of acetylene.It was found that Ni_xGa/SiO_2 showed higher selectivity to ethylene than Ni/Si O_2.This is attributed to the formation Ni-Ga alloy and Ni3 Ga intermetallic compound(IMC) where there was a charge transfer from Ga to Ni,which is favorable for reducing the adsorption strength and amount of ethylene on Ni atoms.As a result,the over-hydrogenation,the C–C bond hydrogenolysis and the polymerization were suppressed,and subsequently the selectivity to ethylene was enhanced.With the decrease of Ni/Ga atomic ratio,the activity and stability of the Ni_xGa/SiO_2 catalysts increased first and then decreased,while the ethylene selectivity tended to increase.Ni_5 Ga/SiO_2 exhibited the best performance.Under the conditions of 180 °C,0.1 MPa,and a reactant(1.0 vol% acetylene,5.0 vol% H_2 and 94 vol% N_2) with the space velocity of 36,000 m L h^(-1) g^(-1),the acetylene conversion maintained at 100% on Ni_5 Ga/SiO_2 during 120 h time on stream and the selectivity to ethylene was 75%~81%after reaction for 68 h.It was also found that the formation of Ni-Ga alloy and Ni_3 Ga IMC suppressed the incorporation of carbon to form NiCx,subsequently enhancing the catalyst stability.Additionally,with increasing the Ga content,the catalyst acid amount and strength tended to increase,which promoted the polymerization and carbon deposition and so the catalyst deactivation.
文摘The chemical thermodynamic equilibrium of acetylene production by coal pyrolysis in hydrogen plasma was studied. The thermodynamic equilibrium is obtained by using the method of free energy. Calculated results show that the hydrogen concentration in the equilibrium system is very important for the acetylene production by coal conversion and the energy consumption for the production of acetylene per-kilogram strongly depends on the hydrogen concentration and the temperature.
基金supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry
文摘A novel chiral methylpropargyl ester containing azobenzene moiety(S)-(-)-3-methyl-3-{4-[4-(n-octyloxy)phenylazophenyl]carbonyl}oxy-1-propyne 3(C25H30N2O3,Mr = 406.51) was synthesized and characterized by IR,NMR and single-crystal X-ray diffraction.The crystal is of monoclinic system,space group P21 with a=6.7610(17),b=7.675(2),c=22.749(7),β=97.613(6)°,V=1170.1(6)3,Z=2,Dc=1.154,F(000)=436,μ=0.076 mm-1,R=0.0544 and wR=0.1569 for 2444 observed reflections with Ⅰ〉2σ(Ⅰ).Structure analysis proved that the azobenzene presents a trans form, and intermolecular hydrogen bonds yield a 3D framework. The ehiral acetylene carrying azobenzene moieties can be a potential alternative nonlinear optical, helical polymer, and liquid crystalline material.
基金supported by the Knowledge Innovation Engineering of Chinese Academy of Sciences under contract No.KZCX3-SW-214,KSCX2-SW-132the Natural Science Foundation of Guangdong Province under contract No.032622.
文摘The concentrations of nitrous oxide varies between 57 and 329 nmol/dm3, saturation is 674%~4 134% in the Zhujiang River Estuary. This suggests that the area is an emissive source of nitrous oxide. The acetylene inhibition technique is employed to evaluate the rates of nitrification, denitrification and nitrate reduction by bacterial activities in the sediments at three sites. The average of nitrification, denitrification and nitrate reduction rates ranges from 0.32 to 2.43, 0.03 to 0.84 and 4.17 to 13.06 mmol/(m2·h), respectively. The ver- tical profiles of the sediments show that the nitrification and denitrification processes mainly take place in the depth from 0 to 4 cm and depend on regional conditions. The rates of nitrification, denitrification and nitrate reduction are dominated by Eh, nitrate and ammoni- um concentrations in sediments and DO in overlay water. There is a coupling between nitrification and denitrification.
基金supported by the National Natural Science Foundation of China (Grant No. 20833011 and 20877015)the State Hi-tech Research and Development Project of the Ministry of Science and Technology of China (Grant No. 2008AA06Z319)
文摘Ce-A12O3 catalysts prepared by co-precipitation are investigated both in NO oxidation by 02 and in selective catalytic reduction of NO by C2H2 (C2H2-SCR). It is found that C2H2-SCR is initiated and controlled by NO oxidation to NO2 over A12O3. Ce loading on A12O3 is almost inactive for NO oxidation below 350℃, since NO2 strongly adsorbs on cerium oxide, leading to the active sites being blocked, which was characterized by temperature-programmed desorption of NO and NO2 and Fourier transform infrared spectroscopy after NO+O2 coadsorption over the samples. However, in the case of C2H2-SCR, Ce loading on A1203 significantly improves the reaction by accelerating the NO oxidation step in the temperature range of 250-450℃, since the nitrate species produced by NO2 adsorption is an active intermediate required by C2H2-SCR.
基金Financial support by the Fundamental Research Funds for the Central Universities(No.buctrc201727)the Natural Science Foundation of China(No.21536001,21722602,and 21322603)。
文摘Cost effective separation of acetylene(C_2H_2)and ethylene(C_2H_4)is of key importance to obtain essential chemical raw materials for polymer industry.Due to the low compression limit of C_2H_2,there is an urgent demand to develop suitable materials for efficiently separating the two gases under ambient conditions.In this paper,we provided a high-throughput screening strategy to study porous metal-organic frameworks(MOFs)containing open metal sites(OMS)for C_2H_2/C_2H_4 separation,followed by a rational design of novel MOFs in-silico.A set of accurate force fields was established from ab initio calculations to describe the critical role of OMS towards guest molecules.From a large-scale computational screening of 916 experimental Cu-paddlewheel-based MOFs,three materials were identified with excellent separation performance.The structure-performance relationships revealed that the optimal materials should have the largest cavity diameter around 5-10?and pore volume in-between 0.3-1.0 cm^3 g^(-1).Based on the systematic screening study result,three novel MOFs were further designed with the incorporation of fluorine functional group.The results showed that Cu-OMS and the-F group on the aromatic rings close to Cu sites could generate a synergistic effect on the preferential adsorption of C_2H_2 over C_2H_4,leading to a remarkable improvement of C_2H_2 separation performance of the materials.The findings could provide insight for future experimental design and synthesis of high-performance nanostructured materials for C_2H_2/C_2H_4 separation.
文摘A new preparation method was proposed to deposit amorphous alloys alloys containing NiPand metallic metallic additives such as Fe.Co. and Cu.The different effects of metallic additive onstructure and catalytic properties of supported amorphous NiMPB/SiO2 (M=Fe, Co. Cu) cafalysts were observed,and the improvement of catalytic activity due to heating pretreatment in hydrogenwas found.
基金supported by the National Natural Science Foundation of China(No.11074038)
文摘Methane coupling in microwave plasma under atmospheric pressure has been investigated.The effects of molar ratio n(CH4)/n(H2),flow rate and microwave power on the reaction have been studied.(1)With the decrease of n(CH4)/n(H2)ratio,methane conversion,C2 hydrocarbon yield,energy yield and space-time yield of acetylene increased,but the yield of carbon deposit decreased.(2)With the increase of microwave power,energy yield of acetylene decreased,but space-time yield of acetylene increased.(3)With the increase of flow rate,energy yield and space-time yield of acetylene increased first and then decreased.Finally,under the reaction conditions of CH4 flow rate of 700 mL/min,n(CH4)/n(H2)ratio of 1/4 and microwave power of 400 W,the energy yield and space-time yield of acetylene could reach 0.337 mmol/kJ and 12.3 mol/(s m3),respectively.The reaction mechanism of methane coupling in microwave plasma has been investigated based on the thermodynamics of chemical reaction.Interestingly,the acetylene yield of methane coupling in microwave plasma was much higher than the maximum thermodynamic yield of acetylene.This phenomenon was tentatively explained from non-expansion work in the microwave plasma system.