The study of the leaching of vanadium(V) and molybdenum(Mo) from spent petrochemical catalysts in sodium hydroxide(NaO H) medium was performed using two approaches, namely, conventional leaching and microwave-assisted...The study of the leaching of vanadium(V) and molybdenum(Mo) from spent petrochemical catalysts in sodium hydroxide(NaO H) medium was performed using two approaches, namely, conventional leaching and microwave-assisted leaching methods. The influence of microwave power, leaching time, leaching temperature, and NaOH concentration on the leaching efficiency of spent petrochemical catalyst was investigated. Under microwave-assisted conditions(600 W, 10 min, 90°C, 2.0 mol·L^(-1) NaOH, and 0.20 g·mL^(-1) solid–liquid ratio), the leaching efficiencies of V and Mo reached 94.35% and 96.23%, respectively. It has been confirmed that microwave energy has considerable potential to enhance the efficiency of the leaching process and reduce the leaching time. It is suggested that the enhancement of the leaching efficiencies of V and Mo can be attributed to the existence of a thermal gradient between solid and liquid and the generation of cracks on the mineral surface.展开更多
Large quantities of spent hydrodesulfurization (HDS) catalysts are available from petrochemical industry. Disposal of spent catalyst is a problem as it falls under the category of hazardous industrial waste due to its...Large quantities of spent hydrodesulfurization (HDS) catalysts are available from petrochemical industry. Disposal of spent catalyst is a problem as it falls under the category of hazardous industrial waste due to its vanadium concentration. Most of these catalysts are usually supported on alumina containing a variable percentage of elements such as nickel or molybdenum. Hence these catalysts contain environmentally critical, and economically valuable metals such as molyb denum, vanadium, and, nickel. In this paper, a spent HDS catalyst was treated with caustic soda solution. Parameters such as temperature, time, and NaOH solution concentration have been studied thoroughly, in order to settle the appropriate conditions for the maximum recovery of molybdenum and vanadium. Under the best leaching conditions (20 %w NaOH, room temperature, 2 h) about 95% recovery of Mo and V was achieved, and the recovery of nickel obtained was of 99% in the form of NiAlO4.展开更多
Boehmite nanoparticles with a high surface area and a high degree of surface hydroxyl groups were covalently functionalized by 3‐（trimethoxysilyl）‐propylamine to support vanadium‐oxo‐sulfate and molybdenum hexac...Boehmite nanoparticles with a high surface area and a high degree of surface hydroxyl groups were covalently functionalized by 3‐（trimethoxysilyl）‐propylamine to support vanadium‐oxo‐sulfate and molybdenum hexacarbonyl complexes. These supported catalysts were then characterized by Fou‐rier‐transform infrared spectroscopy, powder X‐ray diffraction, thermogravimetry and differential thermal analysis, X‐ray‐photoelectron spectroscopy, elemental analysis, inductively coupled plasma, and transmission electron microscopy techniques. The catalysts were subsequently used for the epoxidation of cis‐cyclooctene, and the experimental procedures were optimized. The progress of the reactions was investigated by gas‐liquid chromatography. Recycling experiments revealed that these nanocatalysts could be repeatedly used several times for a nearly complete epoxidation of cis‐cyclooctene. The optimized experimental conditions were also used successfully for the epoxida‐tion of some other substituted alkenes.展开更多
A series of supported molybdenum phosphide catalysts were prepared by impregnation method. XRD, TG-DTG, XPS and BET were used to study the phase, compositions and surface areas of the prepared catalysts. A model react...A series of supported molybdenum phosphide catalysts were prepared by impregnation method. XRD, TG-DTG, XPS and BET were used to study the phase, compositions and surface areas of the prepared catalysts. A model reactant containing thiophene, pyridine and cyclohexene was used for the measurements of catalytic activities. The effect of reduction temperature on catalytic activities was investigated. The analysis results by XRD and BET are very different when the reduction temperature is changed from 400 to 900 ℃. MoP/γ-Al2O3 catalysts and CoMoP/γ-Al2O3 catalysts prepared at the reduction temperature of 500 ℃ are the most active ones.展开更多
The dispersion of functional nanometer materials in polyolefin/clay nanocomposites is a key factor to determine the performances of mate-rials[1].In this research,the sepiolite with high specific surface area and good...The dispersion of functional nanometer materials in polyolefin/clay nanocomposites is a key factor to determine the performances of mate-rials[1].In this research,the sepiolite with high specific surface area and good adsorption was introduced into the molybdenum-based butadiene polymerization system.Sepiolite-supporting MoCl5(Mo)function as the main catalysts,together with the alkyl aluminum(Al)substituted by m-cresol to form the butadiene coordination polymerization catalyst system to prepare high vinyl polybutadiene(HVPB)/sepiolite(Sep)nanocomposite.展开更多
The alcohol synthesis with a good proportion of higher alcohols was studied over promoted Co/CuLaZr catalysts. the molybdenum addition improved greatly the performance. The results of probe molecule tests could be use...The alcohol synthesis with a good proportion of higher alcohols was studied over promoted Co/CuLaZr catalysts. the molybdenum addition improved greatly the performance. The results of probe molecule tests could be used to explain the effects.展开更多
Transition metal molybdenum phosphides were prepared by direct reduction of an amorphous phosphate precursor in hydrogen at relatively low temperature (650 ℃). XRD (X ray diffraction analysis) measurements showed tha...Transition metal molybdenum phosphides were prepared by direct reduction of an amorphous phosphate precursor in hydrogen at relatively low temperature (650 ℃). XRD (X ray diffraction analysis) measurements showed that pure molybdenum phosphide formed after the reduction with H 2. The reactivity was determined in a continuous flow microreactor at a H 2 pressure of 3.0 MPa. A sample of prepared molybdenum phosphide catalyst diluted with γ Al 2O 3 (20% phosphate precursor) was used for simultaneous HDN (Hydrodenitrogenation), HDS (Hydrodesulfurization) and HDY(Hydrogenation of aromatics). The influences of space velocity, flow rate of hydrogen, reaction time and temperature on hydrotreating performance were studied. Pyridine, thiophene and cyclohexene were used as model compounds, their contents were respectively 5%, 5% and 20%. Cyclohexane was used as the solvent.展开更多
Results of research of supercritical fluid CO2-regeneration process of Nickel-Molybdenum Catalysts DN-3531 and Criterion 514 are given. Regeneration was carried out with the use of pure supercritical carbon dioxide an...Results of research of supercritical fluid CO2-regeneration process of Nickel-Molybdenum Catalysts DN-3531 and Criterion 514 are given. Regeneration was carried out with the use of pure supercritical carbon dioxide and mixture of supercritical carbon dioxide and various polar cosolvents. Regeneration process is carried out along isotherms, in the temperature range of 323 - 383 K, at pressures of P = 20 MPa and 30 MPa. Results of surface assessment of the catalyst samples regenerated show high effectiveness of suggested method.展开更多
Nitrogen electro-reduction under mild conditions is one promising alternative approach of the energyconsuming Haber-Bosch process for the artificial ammonia synthesis.One critical aspect to unlocking this technology i...Nitrogen electro-reduction under mild conditions is one promising alternative approach of the energyconsuming Haber-Bosch process for the artificial ammonia synthesis.One critical aspect to unlocking this technology is to discover the catalysts with high selectivity and efficiency.In this work,the N_(2)-to-NH_(3)conversion on the functional MoS_(2)is fully investigated by density functional theory calculations since the layered MoS_(2)provides the ideal platform for the elaborating copies of the nitrogenase found in nature,wherein the functionalization is achieved via basal-adsorption,basal-substitution or edge-substitution of transition metal elements.Our results reveal that the edge-functionalization is a feasible strategy for the activity promotion;however,the basal-adsorption and basal-substitution separately suffer from the electrochemical instability and the NRR inefficiency.Specifically,MoS_(2)functionalized via edge W-substitution exhibits an exceptional activity.The energetically favored reaction pathway is through the distal pathway and a limiting potential is less than 0.20 V.Overall,this work escalates the rational design of the high-effective catalysts for nitrogen fixation and provides the explanation why the predicated catalyst have a good performance,paving the guidance for the experiments.展开更多
Electrocatalytic water splitting is crucial for H2generation via hydrogen evolution reaction(HER)but subject to the sluggish dynamics of oxygen evolution reaction(OER).In this work,single Fe atomdoped MoS_(2)nanosheet...Electrocatalytic water splitting is crucial for H2generation via hydrogen evolution reaction(HER)but subject to the sluggish dynamics of oxygen evolution reaction(OER).In this work,single Fe atomdoped MoS_(2)nanosheets(SFe-DMNs)were prepared based on the high-throughput density functional theory(DFT)calculation screening.Due to the synergistic effect between Fe atom and MoS_(2)and optimized intermediate binding energy,the SFe-DMNs could deliver outstanding activity for both HER and OER.When assembled into a two-electrode electrolytic cell,the SFe-DMNs could achieve the current density of 50 mA cm^(-2)at a low cell voltage of 1.55 V under neutral condition.These results not only confirmed the effectiveness of high-throughput screening,but also revealed the excellent activity and thus the potential applications in fuel cells of SFe-DMNs.展开更多
基金financially supported by the High-degree Talent Introduction Program of Guangdong Academy of Sciences(No.2017GDASCX-0841)the Science and Technology Program of Guangzhou(No.201607020021)+2 种基金the National Natural Science Foundation of China(No.51304055)the Innovative Platform Construction Program of Guangdong Academy of Sciences(No.2017GDASCX-0109)the Pearl River Nova Program of Guangzhou(No.201806010016)
文摘The study of the leaching of vanadium(V) and molybdenum(Mo) from spent petrochemical catalysts in sodium hydroxide(NaO H) medium was performed using two approaches, namely, conventional leaching and microwave-assisted leaching methods. The influence of microwave power, leaching time, leaching temperature, and NaOH concentration on the leaching efficiency of spent petrochemical catalyst was investigated. Under microwave-assisted conditions(600 W, 10 min, 90°C, 2.0 mol·L^(-1) NaOH, and 0.20 g·mL^(-1) solid–liquid ratio), the leaching efficiencies of V and Mo reached 94.35% and 96.23%, respectively. It has been confirmed that microwave energy has considerable potential to enhance the efficiency of the leaching process and reduce the leaching time. It is suggested that the enhancement of the leaching efficiencies of V and Mo can be attributed to the existence of a thermal gradient between solid and liquid and the generation of cracks on the mineral surface.
文摘Large quantities of spent hydrodesulfurization (HDS) catalysts are available from petrochemical industry. Disposal of spent catalyst is a problem as it falls under the category of hazardous industrial waste due to its vanadium concentration. Most of these catalysts are usually supported on alumina containing a variable percentage of elements such as nickel or molybdenum. Hence these catalysts contain environmentally critical, and economically valuable metals such as molyb denum, vanadium, and, nickel. In this paper, a spent HDS catalyst was treated with caustic soda solution. Parameters such as temperature, time, and NaOH solution concentration have been studied thoroughly, in order to settle the appropriate conditions for the maximum recovery of molybdenum and vanadium. Under the best leaching conditions (20 %w NaOH, room temperature, 2 h) about 95% recovery of Mo and V was achieved, and the recovery of nickel obtained was of 99% in the form of NiAlO4.
基金the vice-president's office for research affairs of Shahrood University of Technology for the financial support of this work
文摘Boehmite nanoparticles with a high surface area and a high degree of surface hydroxyl groups were covalently functionalized by 3‐（trimethoxysilyl）‐propylamine to support vanadium‐oxo‐sulfate and molybdenum hexacarbonyl complexes. These supported catalysts were then characterized by Fou‐rier‐transform infrared spectroscopy, powder X‐ray diffraction, thermogravimetry and differential thermal analysis, X‐ray‐photoelectron spectroscopy, elemental analysis, inductively coupled plasma, and transmission electron microscopy techniques. The catalysts were subsequently used for the epoxidation of cis‐cyclooctene, and the experimental procedures were optimized. The progress of the reactions was investigated by gas‐liquid chromatography. Recycling experiments revealed that these nanocatalysts could be repeatedly used several times for a nearly complete epoxidation of cis‐cyclooctene. The optimized experimental conditions were also used successfully for the epoxida‐tion of some other substituted alkenes.
文摘A series of supported molybdenum phosphide catalysts were prepared by impregnation method. XRD, TG-DTG, XPS and BET were used to study the phase, compositions and surface areas of the prepared catalysts. A model reactant containing thiophene, pyridine and cyclohexene was used for the measurements of catalytic activities. The effect of reduction temperature on catalytic activities was investigated. The analysis results by XRD and BET are very different when the reduction temperature is changed from 400 to 900 ℃. MoP/γ-Al2O3 catalysts and CoMoP/γ-Al2O3 catalysts prepared at the reduction temperature of 500 ℃ are the most active ones.
基金Supported by Shandong Provincial Natural Science Foundation(ZR 2020 ME 059).
文摘The dispersion of functional nanometer materials in polyolefin/clay nanocomposites is a key factor to determine the performances of mate-rials[1].In this research,the sepiolite with high specific surface area and good adsorption was introduced into the molybdenum-based butadiene polymerization system.Sepiolite-supporting MoCl5(Mo)function as the main catalysts,together with the alkyl aluminum(Al)substituted by m-cresol to form the butadiene coordination polymerization catalyst system to prepare high vinyl polybutadiene(HVPB)/sepiolite(Sep)nanocomposite.
文摘The alcohol synthesis with a good proportion of higher alcohols was studied over promoted Co/CuLaZr catalysts. the molybdenum addition improved greatly the performance. The results of probe molecule tests could be used to explain the effects.
文摘Transition metal molybdenum phosphides were prepared by direct reduction of an amorphous phosphate precursor in hydrogen at relatively low temperature (650 ℃). XRD (X ray diffraction analysis) measurements showed that pure molybdenum phosphide formed after the reduction with H 2. The reactivity was determined in a continuous flow microreactor at a H 2 pressure of 3.0 MPa. A sample of prepared molybdenum phosphide catalyst diluted with γ Al 2O 3 (20% phosphate precursor) was used for simultaneous HDN (Hydrodenitrogenation), HDS (Hydrodesulfurization) and HDY(Hydrogenation of aromatics). The influences of space velocity, flow rate of hydrogen, reaction time and temperature on hydrotreating performance were studied. Pyridine, thiophene and cyclohexene were used as model compounds, their contents were respectively 5%, 5% and 20%. Cyclohexane was used as the solvent.
文摘Results of research of supercritical fluid CO2-regeneration process of Nickel-Molybdenum Catalysts DN-3531 and Criterion 514 are given. Regeneration was carried out with the use of pure supercritical carbon dioxide and mixture of supercritical carbon dioxide and various polar cosolvents. Regeneration process is carried out along isotherms, in the temperature range of 323 - 383 K, at pressures of P = 20 MPa and 30 MPa. Results of surface assessment of the catalyst samples regenerated show high effectiveness of suggested method.
基金financial support from the National Natural Science Foundation of China(21503097,52130101,51701152,21806023,and 51702345)China Scholarship Council(202008320215).
文摘Nitrogen electro-reduction under mild conditions is one promising alternative approach of the energyconsuming Haber-Bosch process for the artificial ammonia synthesis.One critical aspect to unlocking this technology is to discover the catalysts with high selectivity and efficiency.In this work,the N_(2)-to-NH_(3)conversion on the functional MoS_(2)is fully investigated by density functional theory calculations since the layered MoS_(2)provides the ideal platform for the elaborating copies of the nitrogenase found in nature,wherein the functionalization is achieved via basal-adsorption,basal-substitution or edge-substitution of transition metal elements.Our results reveal that the edge-functionalization is a feasible strategy for the activity promotion;however,the basal-adsorption and basal-substitution separately suffer from the electrochemical instability and the NRR inefficiency.Specifically,MoS_(2)functionalized via edge W-substitution exhibits an exceptional activity.The energetically favored reaction pathway is through the distal pathway and a limiting potential is less than 0.20 V.Overall,this work escalates the rational design of the high-effective catalysts for nitrogen fixation and provides the explanation why the predicated catalyst have a good performance,paving the guidance for the experiments.
基金supported by the Research Funds of Institute of Zhejiang University-Quzhou(IZQ2023RCZX032)the Natural Science Foundation of Guangdong Province(2022A1515010185)+1 种基金the Fundamental Research Funds for the Central Universities(FRF-TP-20-005A3)partially supported by the Special Funds for Postdoctoral Research at Tsinghua University(100415017)。
文摘Electrocatalytic water splitting is crucial for H2generation via hydrogen evolution reaction(HER)but subject to the sluggish dynamics of oxygen evolution reaction(OER).In this work,single Fe atomdoped MoS_(2)nanosheets(SFe-DMNs)were prepared based on the high-throughput density functional theory(DFT)calculation screening.Due to the synergistic effect between Fe atom and MoS_(2)and optimized intermediate binding energy,the SFe-DMNs could deliver outstanding activity for both HER and OER.When assembled into a two-electrode electrolytic cell,the SFe-DMNs could achieve the current density of 50 mA cm^(-2)at a low cell voltage of 1.55 V under neutral condition.These results not only confirmed the effectiveness of high-throughput screening,but also revealed the excellent activity and thus the potential applications in fuel cells of SFe-DMNs.
