Ionic liquids predominantly consist of ionic species[1]and have low melting points[2]usually less than 373 K.They were widely used in organic syn-thesis as green solvents or catalysts[3,4].Recently,Cooper et al[5]repo...Ionic liquids predominantly consist of ionic species[1]and have low melting points[2]usually less than 373 K.They were widely used in organic syn-thesis as green solvents or catalysts[3,4].Recently,Cooper et al[5]reported the preparation of an AEL type aluminophosphate molecular sieve using 1-ethyl-3-methylimidazolium bromide([emim]Br)ionic liq-uid as both the solvent and template.They named the novel attractive procedure ionothermal synthesis to distinguish it from the hydrothermal process.The AEL type aluminophosphate molecular sieve has no acidic sites because of its electrically neutral struc-ture[6].However,introducing Si species to substitute P in the framework will impart mild acidity to the AEL type molecular sieve and make it active for a va-riety of heterogeneous acidic catalytic reactions such as the hydroisomerization of alkane[7.8].In this work,Si species were introduced into the synthesis mixture and the silicoaluminophosphate molecular sieve with AEl structure was ionothermally synthe-sized.Meanwhile,the effect of Si species amount on the product properties was investigated.展开更多
Two series of WP/Al2O3 catalyst precursors with WP mass loading in the range 18.5%—37.1% were prepared using the impregnation method and mixing method, respectively, and the catalysts were then obtained by temperatur...Two series of WP/Al2O3 catalyst precursors with WP mass loading in the range 18.5%—37.1% were prepared using the impregnation method and mixing method, respectively, and the catalysts were then obtained by temperature-programmed reduction of supported tungsten phosphate (precursor of WP/Al2O3 catatlysts) in H2 at 650℃ for 4h. The catalysts were characterized by XRD, BET, TG/DTA , XPS and 31P MAS-NMR. The activities of these catalysts were tested in the hydrodenitrogenation (HDN) of pyridine and hydrodesulfurization (HDS) of thiophene at 340℃ and 3.0MPa. The results showed that owing to the stronger interaction of the support with the active species, the precursor of WP/Al2O3 catalyst was more difficultly phosphided and a greater amount of W spe- cies was in a high valence state W6+ on the surface of the catalyst prepared by the impregnation method than that by the mixing method. 31P MAS-NMR results indicated that 31P shift from 85% H3PO4 of 2.55×10-4 for WP and 2.57 ×10-4 for WP/γ-Al2O3 catalysts prepared by mixing method. Such WP/Al2O3 catalysts showed higher HDN activi- ties and lower HDS activities than those prepared by the impregnation method under the same loading of WP. WP/γ-Al2O3 catalysts with weak interaction between support and active species were favorable for HDN reaction while the WP/γ-Al2O3 catalysts with strong interaction were favorable for HDS reaction.展开更多
A series of 12-molybdophosphoric acid (MPA) supported on V2O5 dispersed γ-Al2O3 catalysts with different vanadia loadings were prepared by impregnation and characterized by N2 adsorption-desorption, X-ray diffraction...A series of 12-molybdophosphoric acid (MPA) supported on V2O5 dispersed γ-Al2O3 catalysts with different vanadia loadings were prepared by impregnation and characterized by N2 adsorption-desorption, X-ray diffraction, temperature-programmed reduction, in situ laser Raman spectroscopy, UV-Vis diffused reflectance spectroscopy, scanning electron microscopy, and temperature-programmed desorption of NH3 techniques. Their catalytic activities were evaluated for the vapor phase aerobic oxidation of benzyl alcohol. The catalysts exhibited high catalytic activity and the conversion of benzyl alcohol depended on the vanadia content while the catalyst with 15 wt% V2O5 content showed optimum activity. The characterization results suggest the presence of well-dispersed V2O5 and partially disintegrated Keggin ions of MPA on the support. In situ Raman studies showed a reduced Mo(IV) species when the catalysts were calcined at high temperatures. The high oxidation activity of the catalysts is related to the synergistic effect between MPA and V2O5.展开更多
The ultrafine particles of a new style Fe-Cu-based catalysts for CO hydrogenation were prepared by impregnating the organic sol of Fe（OH）3 and Cu（OH）2 onto the activated Al2O3, in which the organic sol of Fe（OH）...The ultrafine particles of a new style Fe-Cu-based catalysts for CO hydrogenation were prepared by impregnating the organic sol of Fe（OH）3 and Cu（OH）2 onto the activated Al2O3, in which the organic sol of Fe（OH）3 and Cu（OH）2 were prepared in the microemulsion of dodecylbenzenesulfonic acid sodium（S）/n-butanol（A）/toluene（O）/water with V（A）/V（O） = 0.25 and W（A）/W（S） = 1.50. This catalyst was characterized by particle size analysis, XRD and TG. The results of particle size analysis showed that Fe（OH）3 particles with a mean size of 17.1 nm and Cu（OH）2 particles with an average size of 6.65 um were obtained. TG analysis and XRD patterns suggested that 673 K is the optimal calcination temperature. CO hydrogenation produced C＋OH with a high selectivity above 58 wt% by using the ultrafine particles as catalyst, and the total alcohol yield of 0.250 g·ml^-1 ·h^-1 was obtained when the contents of Al2O3 and K were 88.61 wt% and 1.60 wt%, respectively.展开更多
Esterification of acrylic acid（AA） to produce AA esters has widespread application in the chemical industry. A series of water tolerant solid acid catalysts was prepared, and characterized by XRD, nitrogen adsorptio...Esterification of acrylic acid（AA） to produce AA esters has widespread application in the chemical industry. A series of water tolerant solid acid catalysts was prepared, and characterized by XRD, nitrogen adsorption, TGA-DTA, XPS, and ammonia adsorption FTIR. The effects of Si/Al ratio, zirconium sulfate（ZS） loading on HZSM-5 and calcination temperature on the esterification were investigated. When 20% （mass fraction） ZS is loaded on HZSM-5, the conversion of AA reaches 100%. XRD analysis indicates that ZS is highly dispersed on HZSM-5 because no crystalline structure assigned to ZS is found. Catalytic activity and hydrophobicity of ZS supported on HZSM-5 are higher compared with those of parent ZS or HZSM-5. Results show that this kind of novel catalysts is an efficient water tolerant solid acid catalyst for esterification reactions.展开更多
The performance of catalysts used in after-treatment systems is the key factor for the removal of diesel soot,which is an important component of atmosphericfine particle emissions.Herein,three-dimensionally ordered ma...The performance of catalysts used in after-treatment systems is the key factor for the removal of diesel soot,which is an important component of atmosphericfine particle emissions.Herein,three-dimensionally ordered macroporous–mesoporous Ti_(x)Si+(1-x)O_(2)(3DOM-m Ti_(x)Si+(1-x)O_(2))and its supported MnO_(x)catalysts doped with different alkali/alkaline-earth metals(AMnO_(x)/3 DOM-m Ti_(0.7)Si_(0.3)O_(2)(A:Li,Na,K,Ru,Cs,Mg,Ca,Sr,Ba))were prepared by mesoporous template(P123)-assisted colloidal crystal template(CCT)and incipient wetness impregnation methods,respectively.Physicochemical characterizations of the catalysts were performed using scanning electron microscopy,X-ray diffraction,N_(2)adsorption–desorption,H_(2)temperature-programmed reduction,O_(2)temperature-programmed desorption,NO temperature-programmed oxidation,and Raman spectroscopy techniques;then,we evaluated their catalytic performances for the removal of diesel soot particles.The results show that the 3DOM-m Ti_(0.7)Si_(0.3)O_(2)supports exhibited a well-defined 3DOM-m nanostructure,and AMnO_(x)nanoparticles with 10–50 nm were evenly dispersed on the inner walls of the uniform macropores.In addition,the as-prepared catalysts exhibited good catalytic performance for soot combustion.Among the prepared catalysts,CsMnO_(x)/3DOM-m Ti_(0.7)Si_(0.3)O_(2)had the highest catalytic activity for soot combustion,with T10,T50,and T90(the temperatures corresponding to soot conversion rates of 10%,50%,and 90%)values of 285,355,and 393℃,respectively.The high catalytic activity of the CsMnO_(x)/3 DOM-m Ti_(0.7)Si_(0.3)O_(2)catalysts was attributed to their excellent low-temperature reducibility and homogeneous macroporous–mesoporous structure,as well as to the synergistic effects between Cs and Mn species and between CsMnO_(x)and the Ti_(0.7)Si_(0.3)O_(2)support.展开更多
The influence of preparation conditions （e.g. H2-N2 ratios, final nitriding temperatures） on the performance of MoNx/SBA-15 catalysts for ammonia decomposition was investigated. The variation of catalytic activity w...The influence of preparation conditions （e.g. H2-N2 ratios, final nitriding temperatures） on the performance of MoNx/SBA-15 catalysts for ammonia decomposition was investigated. The variation of catalytic activity with H2-N2 ratios may be attributed to the variation of surface compositions and particle sizes of the active components. The variation of nitriding temperatures leads to the formation of molybdenum nitride domains of varying compositions, which are responsible for the difference in their catalytic performance with respect to ammonia decomposition. At 923 K, ammonia could be completely decomposed using 15800 ml/h·gcat of GHSVNH3, which shows high performance for the catalytic decomposition of ammonia.展开更多
The use of clay minerals in the synthesis of nanosized noble metal particles to give increased catalytic activity was investigated. Nanosized platinum and ruthenium catalysts intercalated in clay (montmorillonite/hect...The use of clay minerals in the synthesis of nanosized noble metal particles to give increased catalytic activity was investigated. Nanosized platinum and ruthenium catalysts intercalated in clay (montmorillonite/hectorite) were synthesised and their catalytic activity was evaluated for the selective hydrogenation of three different α,β-unsaturated aldehydes, namely, crotonaldehyde, cinnamaldehyde, and citral, in a gas phase microreactor. The metal nano-sol was prepared by the chemical reduction of its precursor by the micellar technique in the presence of cetyl trimethyl ammonium bromide (CTAB), and the micelle stabilized metal particles were intercalated in the clay mineral by ion exchange. TEM micrographs of the catalyst particles showed that the metal particles were in the nanometre range. The average diameters of the particles were 1-25 nm. The effects of temperature, metal loading, and hydrogen flow rate on the catalytic activity and selectivity for α,β- unsaturated alcohol were studied. The results were correlated with the structural properties of the catalysts. The products formed in each reaction over the different catalysts showed that the catalysts were very active for hydrogenation, and the selectivity for the desired product, namely, α,β-unsaturated alcohol, was good. The metal catalysts intercalated in montmorillonite showed better selectivity than that in hectorite because of its higher acidity. Increased selectivity for α,β-unsaturated alcohol was observed with increased flow rate of hydrogen.展开更多
Nanocrystalline zirconia powder with high surface area and high tetragonal phase percentage is prepared by the precipitation method using ammonium hydroxide as a precipitating agent. The pH of precipitation, preparati...Nanocrystalline zirconia powder with high surface area and high tetragonal phase percentage is prepared by the precipitation method using ammonium hydroxide as a precipitating agent. The pH of precipitation, preparation temperature and calcinations＇ temperature are optimized.Crystallite size, specific surface area, tetragonal phase percentage and the thermal stability of the prepared samples are identified by diferent characterization tools such as X-ray difraction（XRD）, thermo gravimetric analysis（TGA）, diferential scanning calorimetry（DSC）, BET surface area, scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. The optimum preparation parameters for obtaining nanocrystalline zirconia with high percentage of tetragonal phase and high surface area are pH 9, preparation temperature of 80℃ and calcinations＇ temperature of 400℃. The sample prepared under optimized conditions showed a high specific surface area of 179.2 m2/g, high tetragonal phase percentage of 81% and high catalytic activity（60%） for synthesis of butyl acetate ester.展开更多
Solar-powered carbon dioxide （CO_2）-to-fuel conversion presents itself as an ideal solution for both CO_2 mit- igation and the rapidly growing world energy demand. In this work, the heating effect of light irradiati...Solar-powered carbon dioxide （CO_2）-to-fuel conversion presents itself as an ideal solution for both CO_2 mit- igation and the rapidly growing world energy demand. In this work, the heating effect of light irradiation onto a bed of supported nickel （Ni） catalyst was utilized to facilitate CO_2 conversion. Ceria （CeO_2）-titania （TiO_2） oxide supports of different compositions were employed and their effects on photothermal CO_2 conver- sion examined, Two factors are shown to be crucial for instigating photothermal CO_2 methanation activity： ① Fine nickel deposits are required for both higher active catalyst area and greater light absorption capacity for the initial heating of the catalyst bed; and ② the presence of defect sites on the support are necessary to promote adsorption of C02 for its subsequent activation, Titania inclusion within the support plays a crucial role in maintaining the oxygen vacancy defect sites on the （titanium-doped） cerium oxide. The combination of elevated light absorption and stabilized reduced states for CO_2 adsorption subsequently invokes effective Dhotothermal CO_2 methanation when the ceria and titania are blended in the ideal ratio（s）.展开更多
Amorphous aluminophosphate(AlP) and metal-aluminophosphates(MAlPs, where M = 2.5 mol%Cu, Zn, Cr, Fe, Ce, or Zr) were prepared by coprecipitation method. Their surface properties and catalytic activity for the synthesi...Amorphous aluminophosphate(AlP) and metal-aluminophosphates(MAlPs, where M = 2.5 mol%Cu, Zn, Cr, Fe, Ce, or Zr) were prepared by coprecipitation method. Their surface properties and catalytic activity for the synthesis of jasminaldehyde through the aldol condensation of nheptanal and benzaldehyde were investigated. The nitrogen adsorption-desorption isotherms showed that the microporosity exhibited by the aluminophosphate was changed to a mesoporous and macroporous structure which depended on the metal incorporated, with a concomitant change in the surface area. Temperature-programmed desorption of NHand COrevealed that the materials possessed both acidic and basic sites. The acidic strength of the material was either increased or decreased depending on the nature of the metal. The basicity was increased compared to AlP. All the materials were X-ray amorphous and powder X-ray diffraction studies indicated the absence of metal oxide phases. The Fourier transform infrared analysis confirmed the presence of phosphate groups and also the absence of any M-O moieties in the materials. The selected organic reaction occurred only in the presence of the AlP and MAlPs. The selectivity for the jasminaldehyde product was up to 75% with a yield of 65%. The best conversion of nheptanal with a high selectivity to jasminaldehyde was obtained with FeAlP as the catalyst, and this material was characterized to have less weak acid sites and more basic sites.展开更多
Photooxidative removal of pharmaceuticals and organic dyes is an effective way to eliminate growing micropollutants. However, photooxidation often results in byproducts as secondary hazardous substances such as phytot...Photooxidative removal of pharmaceuticals and organic dyes is an effective way to eliminate growing micropollutants. However, photooxidation often results in byproducts as secondary hazardous substances such as phytotoxins. Herein, we found that photooxidation of common antibiotic tetracycline hydrochloride(TCH) over a metal-free 8-hydroxyquinoline(8-HQ) functionalized carbon nitride(CN) photocatalyst significantly reduces the TCH phytotoxic effect. The phytotoxicity test of photocatalytic treated TCH-solution evaluated towards seed growth of Cicer arietinum plant model endowed natural root and shoot growth.This study highlights the conceptual insights in designing of metal-free photocatalyst for environmental remediation.展开更多
In this study, alumina, zirconia, manganese oxide/alumina, and manganese oxide/zirconia have been investigated for their catalytic activity in the condensation reaction between o-phenylenediamine and an aldehyde or a ...In this study, alumina, zirconia, manganese oxide/alumina, and manganese oxide/zirconia have been investigated for their catalytic activity in the condensation reaction between o-phenylenediamine and an aldehyde or a ketone to synthesise 2-substituted benzimidazoles and 1,5-disubstituted benzodiazepines respectively. Surface area, surface acidity, and morphology of the catalysts have been analysed and correlated with their catalytic activity. The isolated yields of 2-substituted benzimidazoles and 1,5-disubstituted benzodiazepines are in the range of 30% to 95%. A good correlation between the amount of surface acid sites as well as the surface morphology of the catalysts and the catalytic activity has been observed. This method has been found to be simple and economical. The solid supports could be regenerated and reused without much loss in their activity. Further, the solid supports have been also found to be effective as general catalysts in the condensation of o-phenylenediamine with other substituted aldehydes and ketones.展开更多
A simple and versatile method for the synthesis of 1,5-benzodiazepines from o-phenylenediamine and ketones in the presence of solvents and under solvent-free conditions that used an amorphous mesoporous iron aluminoph...A simple and versatile method for the synthesis of 1,5-benzodiazepines from o-phenylenediamine and ketones in the presence of solvents and under solvent-free conditions that used an amorphous mesoporous iron aluminophosphate as catalyst was developed.High yields with excellent selectivity were obtained with a wide variety of ketones under mild reaction conditions.The catalyst had the advantages of ease of preparation,ease of handling,simple recovery,reusability,non toxicity,and being inexpensive.展开更多
The development of low-cost,robust and efficient non-noble metal electrocatalysts is still a pursuit for the hydrogen evolution reaction(HER).Herein,a self-standing electrocatalyst,Ni_(2)P/CoP nanosheet,was fabricated...The development of low-cost,robust and efficient non-noble metal electrocatalysts is still a pursuit for the hydrogen evolution reaction(HER).Herein,a self-standing electrocatalyst,Ni_(2)P/CoP nanosheet,was fabricated directly on three-dimensional Ni foams by two facile steps,which illustrated both high activity and stability for HER in different electrolytes.Benefiting from the porous structures of nanosheets with large specific surface area and the hybrid Ni_(2)P/CoP,the as-prepared electrocatalyst presented remarkable HER with overpotentials of 65.2 and 87.8 mV to reach a current density of-10 mA cm^(-2)in neutral and alkaline media,respectively.Density function theory calculations revealed a lower activation energy of water dissociation and efficient HER steps of hybrid Ni_(2)P/CoP nanosheets compared with mono CoP.The self-standing electrocatalyst maintained excellent chemical stability.Additionally,the HER process in domestic wastewater was realized with more impressive performance by using Ni_(2)P/CoP nanosheets compared with commercial Pt/C.Hydrogen was continuously generated for 20 h in mildly alkaline dishwashing wastewater.This work provides a feasible way to fabricate non-noble metal and self-standing hybrid bimetallic phosphides for HER in neutral and alkaline media,showing great potential for efficient hydrogen production by re-utilizing wastewater resources.展开更多
The aim of this work was to evaluate the catalytic properties for n-hexane isomerization of bifunctional monometallic (Ni or Pt) and bimetallic catalysts (Pt-Ni), using HMOR zeolite as support. The method used for met...The aim of this work was to evaluate the catalytic properties for n-hexane isomerization of bifunctional monometallic (Ni or Pt) and bimetallic catalysts (Pt-Ni), using HMOR zeolite as support. The method used for metal dispersion in the zeolite was competitive ion exchange using ammine complexes [Ni(NH3)6]Cl2 and [Pt(NH3)4]Cl2 as precursors. The catalysts were characterized by X-Ray diffraction, X-Ray energy dispersion spectroscopy, temperature-programmed reduction and transmission electron microscopy. The n-hexane isomerization reaction using the catalysts was carried out to evaluate the catalyst activity. The reaction was carried out in a fixed bed reactor operating at 250?C, 1 atm, H2/C6 = 9 molar ratio. The profiles obtained from TPR suggest that, for bimetallic catalysts, the presence of platinum facilitates the reduction of Ni2+ cations. The bimetallic catalysts presented a higher activity in the isomerization of n-hexane when compared to the monometallic ones, as well better stability as the Pt content in the solid increases.展开更多
Reductive pretreatment is an important step for activating supported metal catalysts but has received little attention.In this study,reconstruction of the supported nickel catalyst was found to be sensitive to pretrea...Reductive pretreatment is an important step for activating supported metal catalysts but has received little attention.In this study,reconstruction of the supported nickel catalyst was found to be sensitive to pretreatment conditions.In contrast to the traditional activation procedure in hydrogen,activating the catalyst in syngas created supported Ni nanoparticles with a polycrystalline structure containing an abundance of grain boundaries.The unique post-activation catalyst structure offered enhanced CO adsorption and an improved CO methanation rate.The current strategy to tune the catalyst structure via manipulating the activation conditions can potentially guide the rational design of other supported metal catalysts.展开更多
Titanium dioxide（TiO2） is the most widely studied solid photocatalyst, but when applied to photocatalytic splitting of water to H2 and O2, the evolution rate of H2 is low and decreases with reaction time. The origin...Titanium dioxide（TiO2） is the most widely studied solid photocatalyst, but when applied to photocatalytic splitting of water to H2 and O2, the evolution rate of H2 is low and decreases with reaction time. The origin of the decreasing evolution rate for the photocatalytic splitting of water was investigated for the first time by directly monitoring the surface species on TiO2 during water photocatalysis with in situ attenuated total reflectance（ATR）-Fourier transform infrared（FTIR）spectroscopy. The in situ ATR-FTIR spectroscopic analysis during UV illumination of TiO2 immersed in water reveals that surface dioxygen and hydroxyl species are formed on TiO2： charged Ti—OOH-, peroxo Ti（O2）2-, and bridging Ti—（OH＋）—Ti groups. The accumulation of these surface oxygenated species on the TiO2 photocatalyst blocks the activation of H2O on the surface titania sites and is responsible for the decreasing H2 evolution rate and absence of O2 evolution.展开更多
Mesoporous zirconium oxo phosphate-sulfate was synthesized by hydrothermal method with hexadecyltrithylammonium bromide(CTAB)as the template and with zirconium nitrate or zirconium oxychloride as zirconium source.The ...Mesoporous zirconium oxo phosphate-sulfate was synthesized by hydrothermal method with hexadecyltrithylammonium bromide(CTAB)as the template and with zirconium nitrate or zirconium oxychloride as zirconium source.The optimum two-stage process was established, ^(31)P MAS NMR showed that the states of phosphate species were changed with further postsynthesis treatment by sulfate acid. The transformations of the structures at different temperatures from room temperature to 1173 K were investigated by XRD. ...展开更多
Polymer materials offer controllable structure-dependent performances in separation,catalysis and drug release.Their molecular structures can be precisely tailored to accept Li^(+)for energy storage applications.Here ...Polymer materials offer controllable structure-dependent performances in separation,catalysis and drug release.Their molecular structures can be precisely tailored to accept Li^(+)for energy storage applications.Here the design of sp^(2)carbon-based polyphenylene(PPH)with high lithium-ion uptakes and long-term stability is reported.Linear-PPH(L-PPH)exceeds the performance of crosslink-PPH(C-PPH),due to the fact that it has an ordered lamellar structure,promoting the Li^(+)intercalation/deintercalation channel.The L-PPH cell shows a clear charge and discharge plateau at 0.35 and 0.15 V vs.Li^(+)/Li,respectively,which is absent in the C-PPH cell.The Li^(+)storage capacity of L-PPH is five times that of the C-PPH.The reversible storage capacity is further improved to 261 m Ah g;by functionalizing the L-PPH with the–SO_(3)H groups.In addition,the Li-intercalated structures of C-PPH and L-PPH are investigated via near-edge X-ray absorption fine structure(NEXAFS),suggesting the high reversible Li^(+)–C=C bond interaction at L-PPH.This strategy,based on new insight into sp^(2)functional groups,is the first step toward a molecular understanding of the structure storage-capacity relationship in sp^(2)carbon-based polymer.展开更多
文摘Ionic liquids predominantly consist of ionic species[1]and have low melting points[2]usually less than 373 K.They were widely used in organic syn-thesis as green solvents or catalysts[3,4].Recently,Cooper et al[5]reported the preparation of an AEL type aluminophosphate molecular sieve using 1-ethyl-3-methylimidazolium bromide([emim]Br)ionic liq-uid as both the solvent and template.They named the novel attractive procedure ionothermal synthesis to distinguish it from the hydrothermal process.The AEL type aluminophosphate molecular sieve has no acidic sites because of its electrically neutral struc-ture[6].However,introducing Si species to substitute P in the framework will impart mild acidity to the AEL type molecular sieve and make it active for a va-riety of heterogeneous acidic catalytic reactions such as the hydroisomerization of alkane[7.8].In this work,Si species were introduced into the synthesis mixture and the silicoaluminophosphate molecular sieve with AEl structure was ionothermally synthe-sized.Meanwhile,the effect of Si species amount on the product properties was investigated.
基金Supported by the National Natural Science Foundation of China (No.200273011), the National 973 Project (No.G2000048003)and the Beijing Natural Science Foundation (No.2052009).
文摘Two series of WP/Al2O3 catalyst precursors with WP mass loading in the range 18.5%—37.1% were prepared using the impregnation method and mixing method, respectively, and the catalysts were then obtained by temperature-programmed reduction of supported tungsten phosphate (precursor of WP/Al2O3 catatlysts) in H2 at 650℃ for 4h. The catalysts were characterized by XRD, BET, TG/DTA , XPS and 31P MAS-NMR. The activities of these catalysts were tested in the hydrodenitrogenation (HDN) of pyridine and hydrodesulfurization (HDS) of thiophene at 340℃ and 3.0MPa. The results showed that owing to the stronger interaction of the support with the active species, the precursor of WP/Al2O3 catalyst was more difficultly phosphided and a greater amount of W spe- cies was in a high valence state W6+ on the surface of the catalyst prepared by the impregnation method than that by the mixing method. 31P MAS-NMR results indicated that 31P shift from 85% H3PO4 of 2.55×10-4 for WP and 2.57 ×10-4 for WP/γ-Al2O3 catalysts prepared by mixing method. Such WP/Al2O3 catalysts showed higher HDN activi- ties and lower HDS activities than those prepared by the impregnation method under the same loading of WP. WP/γ-Al2O3 catalysts with weak interaction between support and active species were favorable for HDN reaction while the WP/γ-Al2O3 catalysts with strong interaction were favorable for HDS reaction.
基金supported by the Department of Science & Technology, New Delhi under SERC scheme, DST No. SR/S1/PC-40/2006
文摘A series of 12-molybdophosphoric acid (MPA) supported on V2O5 dispersed γ-Al2O3 catalysts with different vanadia loadings were prepared by impregnation and characterized by N2 adsorption-desorption, X-ray diffraction, temperature-programmed reduction, in situ laser Raman spectroscopy, UV-Vis diffused reflectance spectroscopy, scanning electron microscopy, and temperature-programmed desorption of NH3 techniques. Their catalytic activities were evaluated for the vapor phase aerobic oxidation of benzyl alcohol. The catalysts exhibited high catalytic activity and the conversion of benzyl alcohol depended on the vanadia content while the catalyst with 15 wt% V2O5 content showed optimum activity. The characterization results suggest the presence of well-dispersed V2O5 and partially disintegrated Keggin ions of MPA on the support. In situ Raman studies showed a reduced Mo(IV) species when the catalysts were calcined at high temperatures. The high oxidation activity of the catalysts is related to the synergistic effect between MPA and V2O5.
文摘The ultrafine particles of a new style Fe-Cu-based catalysts for CO hydrogenation were prepared by impregnating the organic sol of Fe（OH）3 and Cu（OH）2 onto the activated Al2O3, in which the organic sol of Fe（OH）3 and Cu（OH）2 were prepared in the microemulsion of dodecylbenzenesulfonic acid sodium（S）/n-butanol（A）/toluene（O）/water with V（A）/V（O） = 0.25 and W（A）/W（S） = 1.50. This catalyst was characterized by particle size analysis, XRD and TG. The results of particle size analysis showed that Fe（OH）3 particles with a mean size of 17.1 nm and Cu（OH）2 particles with an average size of 6.65 um were obtained. TG analysis and XRD patterns suggested that 673 K is the optimal calcination temperature. CO hydrogenation produced C＋OH with a high selectivity above 58 wt% by using the ultrafine particles as catalyst, and the total alcohol yield of 0.250 g·ml^-1 ·h^-1 was obtained when the contents of Al2O3 and K were 88.61 wt% and 1.60 wt%, respectively.
基金Supported by the Research Fund for the Doctoral Program of Higher Education(No20050010014)the China Petroleum &Chemical Corporation ( No X503015 )the Key Discipline Construction Foundation of Beijing Education Committee ( NoXK100100643)
文摘Esterification of acrylic acid（AA） to produce AA esters has widespread application in the chemical industry. A series of water tolerant solid acid catalysts was prepared, and characterized by XRD, nitrogen adsorption, TGA-DTA, XPS, and ammonia adsorption FTIR. The effects of Si/Al ratio, zirconium sulfate（ZS） loading on HZSM-5 and calcination temperature on the esterification were investigated. When 20% （mass fraction） ZS is loaded on HZSM-5, the conversion of AA reaches 100%. XRD analysis indicates that ZS is highly dispersed on HZSM-5 because no crystalline structure assigned to ZS is found. Catalytic activity and hydrophobicity of ZS supported on HZSM-5 are higher compared with those of parent ZS or HZSM-5. Results show that this kind of novel catalysts is an efficient water tolerant solid acid catalyst for esterification reactions.
基金supported by Key Research and Development Program of Ministry of Science and Technology of the People’s Republic of China(MOST)(No.2017YFE0131200)for collaboration between China and PolandNational Nature Science Foundation of China(NSFC)(Nos.22072095,U1908204,21761162016)+3 种基金General Projects of Liaoning Province Natural Fund(No.2019-MS-284)National Engineering Laboratory for Mobile Source Emission Control Technology(No.NELMS2018A04)University level innovation team of Shenyang Normal University,Major Incubation Program of Shenyang Normal University(No.ZD201901)supported by the Research Grants Council(RGC)of Hong Kong through NSFC/RGC Joint Research Scheme(No.N_CUHK451/17)。
文摘The performance of catalysts used in after-treatment systems is the key factor for the removal of diesel soot,which is an important component of atmosphericfine particle emissions.Herein,three-dimensionally ordered macroporous–mesoporous Ti_(x)Si+(1-x)O_(2)(3DOM-m Ti_(x)Si+(1-x)O_(2))and its supported MnO_(x)catalysts doped with different alkali/alkaline-earth metals(AMnO_(x)/3 DOM-m Ti_(0.7)Si_(0.3)O_(2)(A:Li,Na,K,Ru,Cs,Mg,Ca,Sr,Ba))were prepared by mesoporous template(P123)-assisted colloidal crystal template(CCT)and incipient wetness impregnation methods,respectively.Physicochemical characterizations of the catalysts were performed using scanning electron microscopy,X-ray diffraction,N_(2)adsorption–desorption,H_(2)temperature-programmed reduction,O_(2)temperature-programmed desorption,NO temperature-programmed oxidation,and Raman spectroscopy techniques;then,we evaluated their catalytic performances for the removal of diesel soot particles.The results show that the 3DOM-m Ti_(0.7)Si_(0.3)O_(2)supports exhibited a well-defined 3DOM-m nanostructure,and AMnO_(x)nanoparticles with 10–50 nm were evenly dispersed on the inner walls of the uniform macropores.In addition,the as-prepared catalysts exhibited good catalytic performance for soot combustion.Among the prepared catalysts,CsMnO_(x)/3DOM-m Ti_(0.7)Si_(0.3)O_(2)had the highest catalytic activity for soot combustion,with T10,T50,and T90(the temperatures corresponding to soot conversion rates of 10%,50%,and 90%)values of 285,355,and 393℃,respectively.The high catalytic activity of the CsMnO_(x)/3 DOM-m Ti_(0.7)Si_(0.3)O_(2)catalysts was attributed to their excellent low-temperature reducibility and homogeneous macroporous–mesoporous structure,as well as to the synergistic effects between Cs and Mn species and between CsMnO_(x)and the Ti_(0.7)Si_(0.3)O_(2)support.
文摘The influence of preparation conditions （e.g. H2-N2 ratios, final nitriding temperatures） on the performance of MoNx/SBA-15 catalysts for ammonia decomposition was investigated. The variation of catalytic activity with H2-N2 ratios may be attributed to the variation of surface compositions and particle sizes of the active components. The variation of nitriding temperatures leads to the formation of molybdenum nitride domains of varying compositions, which are responsible for the difference in their catalytic performance with respect to ammonia decomposition. At 923 K, ammonia could be completely decomposed using 15800 ml/h·gcat of GHSVNH3, which shows high performance for the catalytic decomposition of ammonia.
基金Supported by FONDECYT, Chile-Post Doctorate-2010 Project (3100010)
文摘The use of clay minerals in the synthesis of nanosized noble metal particles to give increased catalytic activity was investigated. Nanosized platinum and ruthenium catalysts intercalated in clay (montmorillonite/hectorite) were synthesised and their catalytic activity was evaluated for the selective hydrogenation of three different α,β-unsaturated aldehydes, namely, crotonaldehyde, cinnamaldehyde, and citral, in a gas phase microreactor. The metal nano-sol was prepared by the chemical reduction of its precursor by the micellar technique in the presence of cetyl trimethyl ammonium bromide (CTAB), and the micelle stabilized metal particles were intercalated in the clay mineral by ion exchange. TEM micrographs of the catalyst particles showed that the metal particles were in the nanometre range. The average diameters of the particles were 1-25 nm. The effects of temperature, metal loading, and hydrogen flow rate on the catalytic activity and selectivity for α,β- unsaturated alcohol were studied. The results were correlated with the structural properties of the catalysts. The products formed in each reaction over the different catalysts showed that the catalysts were very active for hydrogenation, and the selectivity for the desired product, namely, α,β-unsaturated alcohol, was good. The metal catalysts intercalated in montmorillonite showed better selectivity than that in hectorite because of its higher acidity. Increased selectivity for α,β-unsaturated alcohol was observed with increased flow rate of hydrogen.
文摘Nanocrystalline zirconia powder with high surface area and high tetragonal phase percentage is prepared by the precipitation method using ammonium hydroxide as a precipitating agent. The pH of precipitation, preparation temperature and calcinations＇ temperature are optimized.Crystallite size, specific surface area, tetragonal phase percentage and the thermal stability of the prepared samples are identified by diferent characterization tools such as X-ray difraction（XRD）, thermo gravimetric analysis（TGA）, diferential scanning calorimetry（DSC）, BET surface area, scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. The optimum preparation parameters for obtaining nanocrystalline zirconia with high percentage of tetragonal phase and high surface area are pH 9, preparation temperature of 80℃ and calcinations＇ temperature of 400℃. The sample prepared under optimized conditions showed a high specific surface area of 179.2 m2/g, high tetragonal phase percentage of 81% and high catalytic activity（60%） for synthesis of butyl acetate ester.
基金financially supported by the Australian Research Council under the Laureate Fellowship Scheme (FL140100081)
文摘Solar-powered carbon dioxide （CO_2）-to-fuel conversion presents itself as an ideal solution for both CO_2 mit- igation and the rapidly growing world energy demand. In this work, the heating effect of light irradiation onto a bed of supported nickel （Ni） catalyst was utilized to facilitate CO_2 conversion. Ceria （CeO_2）-titania （TiO_2） oxide supports of different compositions were employed and their effects on photothermal CO_2 conver- sion examined, Two factors are shown to be crucial for instigating photothermal CO_2 methanation activity： ① Fine nickel deposits are required for both higher active catalyst area and greater light absorption capacity for the initial heating of the catalyst bed; and ② the presence of defect sites on the support are necessary to promote adsorption of C02 for its subsequent activation, Titania inclusion within the support plays a crucial role in maintaining the oxygen vacancy defect sites on the （titanium-doped） cerium oxide. The combination of elevated light absorption and stabilized reduced states for CO_2 adsorption subsequently invokes effective Dhotothermal CO_2 methanation when the ceria and titania are blended in the ideal ratio（s）.
基金Sud-Chemie India Ltd. Cochin for support to carry out some of the instrumental analysis work
文摘Amorphous aluminophosphate(AlP) and metal-aluminophosphates(MAlPs, where M = 2.5 mol%Cu, Zn, Cr, Fe, Ce, or Zr) were prepared by coprecipitation method. Their surface properties and catalytic activity for the synthesis of jasminaldehyde through the aldol condensation of nheptanal and benzaldehyde were investigated. The nitrogen adsorption-desorption isotherms showed that the microporosity exhibited by the aluminophosphate was changed to a mesoporous and macroporous structure which depended on the metal incorporated, with a concomitant change in the surface area. Temperature-programmed desorption of NHand COrevealed that the materials possessed both acidic and basic sites. The acidic strength of the material was either increased or decreased depending on the nature of the metal. The basicity was increased compared to AlP. All the materials were X-ray amorphous and powder X-ray diffraction studies indicated the absence of metal oxide phases. The Fourier transform infrared analysis confirmed the presence of phosphate groups and also the absence of any M-O moieties in the materials. The selected organic reaction occurred only in the presence of the AlP and MAlPs. The selectivity for the jasminaldehyde product was up to 75% with a yield of 65%. The best conversion of nheptanal with a high selectivity to jasminaldehyde was obtained with FeAlP as the catalyst, and this material was characterized to have less weak acid sites and more basic sites.
基金the department of science and technology fund for improvement of science and technology infrastructure (DST FIST) (No. SR/FST/CSI-279/2016(C)) for providing XRD and UV-DRS facilitiesthe department of science and technology science and engineering research board (DST-SERB) through the project (No. SB/EMEQ-052/2014 SERB) for financial assistancethe Director, Visvesvaraya National Institute of Technology (VNIT) Nagpur for financial support。
文摘Photooxidative removal of pharmaceuticals and organic dyes is an effective way to eliminate growing micropollutants. However, photooxidation often results in byproducts as secondary hazardous substances such as phytotoxins. Herein, we found that photooxidation of common antibiotic tetracycline hydrochloride(TCH) over a metal-free 8-hydroxyquinoline(8-HQ) functionalized carbon nitride(CN) photocatalyst significantly reduces the TCH phytotoxic effect. The phytotoxicity test of photocatalytic treated TCH-solution evaluated towards seed growth of Cicer arietinum plant model endowed natural root and shoot growth.This study highlights the conceptual insights in designing of metal-free photocatalyst for environmental remediation.
文摘In this study, alumina, zirconia, manganese oxide/alumina, and manganese oxide/zirconia have been investigated for their catalytic activity in the condensation reaction between o-phenylenediamine and an aldehyde or a ketone to synthesise 2-substituted benzimidazoles and 1,5-disubstituted benzodiazepines respectively. Surface area, surface acidity, and morphology of the catalysts have been analysed and correlated with their catalytic activity. The isolated yields of 2-substituted benzimidazoles and 1,5-disubstituted benzodiazepines are in the range of 30% to 95%. A good correlation between the amount of surface acid sites as well as the surface morphology of the catalysts and the catalytic activity has been observed. This method has been found to be simple and economical. The solid supports could be regenerated and reused without much loss in their activity. Further, the solid supports have been also found to be effective as general catalysts in the condensation of o-phenylenediamine with other substituted aldehydes and ketones.
文摘A simple and versatile method for the synthesis of 1,5-benzodiazepines from o-phenylenediamine and ketones in the presence of solvents and under solvent-free conditions that used an amorphous mesoporous iron aluminophosphate as catalyst was developed.High yields with excellent selectivity were obtained with a wide variety of ketones under mild reaction conditions.The catalyst had the advantages of ease of preparation,ease of handling,simple recovery,reusability,non toxicity,and being inexpensive.
基金China Scholarship Council/University College London for joint PhD scholarships,Engineering and Physical Sciences Research Council(EPSRC,EP/V027433/1,EP/L015862/1,EP/R023581/1)supported by the Royal Academy of Engineering under the Research Chairs and Senior Research Fellowships scheme(Brett and Shearing)the Royal Society(RGS\R1\211080,IEC\NSFC\201261)for funding support.
文摘The development of low-cost,robust and efficient non-noble metal electrocatalysts is still a pursuit for the hydrogen evolution reaction(HER).Herein,a self-standing electrocatalyst,Ni_(2)P/CoP nanosheet,was fabricated directly on three-dimensional Ni foams by two facile steps,which illustrated both high activity and stability for HER in different electrolytes.Benefiting from the porous structures of nanosheets with large specific surface area and the hybrid Ni_(2)P/CoP,the as-prepared electrocatalyst presented remarkable HER with overpotentials of 65.2 and 87.8 mV to reach a current density of-10 mA cm^(-2)in neutral and alkaline media,respectively.Density function theory calculations revealed a lower activation energy of water dissociation and efficient HER steps of hybrid Ni_(2)P/CoP nanosheets compared with mono CoP.The self-standing electrocatalyst maintained excellent chemical stability.Additionally,the HER process in domestic wastewater was realized with more impressive performance by using Ni_(2)P/CoP nanosheets compared with commercial Pt/C.Hydrogen was continuously generated for 20 h in mildly alkaline dishwashing wastewater.This work provides a feasible way to fabricate non-noble metal and self-standing hybrid bimetallic phosphides for HER in neutral and alkaline media,showing great potential for efficient hydrogen production by re-utilizing wastewater resources.
基金the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico(CNPq.Brazil)and Petrobras for their financial support to this research.
文摘The aim of this work was to evaluate the catalytic properties for n-hexane isomerization of bifunctional monometallic (Ni or Pt) and bimetallic catalysts (Pt-Ni), using HMOR zeolite as support. The method used for metal dispersion in the zeolite was competitive ion exchange using ammine complexes [Ni(NH3)6]Cl2 and [Pt(NH3)4]Cl2 as precursors. The catalysts were characterized by X-Ray diffraction, X-Ray energy dispersion spectroscopy, temperature-programmed reduction and transmission electron microscopy. The n-hexane isomerization reaction using the catalysts was carried out to evaluate the catalyst activity. The reaction was carried out in a fixed bed reactor operating at 250?C, 1 atm, H2/C6 = 9 molar ratio. The profiles obtained from TPR suggest that, for bimetallic catalysts, the presence of platinum facilitates the reduction of Ni2+ cations. The bimetallic catalysts presented a higher activity in the isomerization of n-hexane when compared to the monometallic ones, as well better stability as the Pt content in the solid increases.
基金sponsored by the National Natural Science Foundation of China (22078089 and 22122807)Natural Science Foundation of Shanghai (21ZR1425700)+1 种基金Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning and Shanghai Sailing Program (19YF1410600)The research at Lehigh University was supported by the Center for Understanding and Control of Acid Gas-Induced Evolution of Materials for Energy (UNCAGE-ME), an Energy Frontier Research Center funded by Department of Energy, Office of Science, Office of Basic Energy Sciences (DE-SC0012577)
文摘Reductive pretreatment is an important step for activating supported metal catalysts but has received little attention.In this study,reconstruction of the supported nickel catalyst was found to be sensitive to pretreatment conditions.In contrast to the traditional activation procedure in hydrogen,activating the catalyst in syngas created supported Ni nanoparticles with a polycrystalline structure containing an abundance of grain boundaries.The unique post-activation catalyst structure offered enhanced CO adsorption and an improved CO methanation rate.The current strategy to tune the catalyst structure via manipulating the activation conditions can potentially guide the rational design of other supported metal catalysts.
文摘Titanium dioxide（TiO2） is the most widely studied solid photocatalyst, but when applied to photocatalytic splitting of water to H2 and O2, the evolution rate of H2 is low and decreases with reaction time. The origin of the decreasing evolution rate for the photocatalytic splitting of water was investigated for the first time by directly monitoring the surface species on TiO2 during water photocatalysis with in situ attenuated total reflectance（ATR）-Fourier transform infrared（FTIR）spectroscopy. The in situ ATR-FTIR spectroscopic analysis during UV illumination of TiO2 immersed in water reveals that surface dioxygen and hydroxyl species are formed on TiO2： charged Ti—OOH-, peroxo Ti（O2）2-, and bridging Ti—（OH＋）—Ti groups. The accumulation of these surface oxygenated species on the TiO2 photocatalyst blocks the activation of H2O on the surface titania sites and is responsible for the decreasing H2 evolution rate and absence of O2 evolution.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant: DICP K2000B3)
文摘Mesoporous zirconium oxo phosphate-sulfate was synthesized by hydrothermal method with hexadecyltrithylammonium bromide(CTAB)as the template and with zirconium nitrate or zirconium oxychloride as zirconium source.The optimum two-stage process was established, ^(31)P MAS NMR showed that the states of phosphate species were changed with further postsynthesis treatment by sulfate acid. The transformations of the structures at different temperatures from room temperature to 1173 K were investigated by XRD. ...
基金funded by the Engineering and Physical Sciences Research Council(EPSRC)(EP/P02467X/1 and EP/S018204/1)the Centre for Nature Inspired Chemical Engineering(EP K038656/1)。
文摘Polymer materials offer controllable structure-dependent performances in separation,catalysis and drug release.Their molecular structures can be precisely tailored to accept Li^(+)for energy storage applications.Here the design of sp^(2)carbon-based polyphenylene(PPH)with high lithium-ion uptakes and long-term stability is reported.Linear-PPH(L-PPH)exceeds the performance of crosslink-PPH(C-PPH),due to the fact that it has an ordered lamellar structure,promoting the Li^(+)intercalation/deintercalation channel.The L-PPH cell shows a clear charge and discharge plateau at 0.35 and 0.15 V vs.Li^(+)/Li,respectively,which is absent in the C-PPH cell.The Li^(+)storage capacity of L-PPH is five times that of the C-PPH.The reversible storage capacity is further improved to 261 m Ah g;by functionalizing the L-PPH with the–SO_(3)H groups.In addition,the Li-intercalated structures of C-PPH and L-PPH are investigated via near-edge X-ray absorption fine structure(NEXAFS),suggesting the high reversible Li^(+)–C=C bond interaction at L-PPH.This strategy,based on new insight into sp^(2)functional groups,is the first step toward a molecular understanding of the structure storage-capacity relationship in sp^(2)carbon-based polymer.
