To better understand the nature of reactive adsorption of thiophene on Ni/ZnO adsorbent,the effect of ZnO textural structure on the desulfurization activity was investigated.ZnO materials were synthesized by low-tempe...To better understand the nature of reactive adsorption of thiophene on Ni/ZnO adsorbent,the effect of ZnO textural structure on the desulfurization activity was investigated.ZnO materials were synthesized by low-temperature solid-state reaction and the corresponding Ni/ZnO adsorbents were prepared by incipient impregnation method.The analysis results showed that the crystalline sizes of ZnO as-synthesized as well as the BET surface areas varied obviously with the calcination temperature.The activity evaluations indicated that the Ni/ZnO adsorbents prepared with ZnO possessed a favorable textural structure as active component exhibited good activity of removing thiophene.The evolutions of the main crystalline phases of Ni/ZnO adsorbents before and after reaction confirmed that ZnO played a crucial role in taking up S element and converting it into ZnS in the reactive adsorption process.It was concluded that ZnO with larger surface area and smaller crystal particles resulted in better desulfurization activity,which may be the main reason for the different activities of the Ni/ZnO adsorbents prepared with ZnO calcined at different temperatures.展开更多
The thiophene removal ability of the synthesized ZnNi/diatomite-pseudo-boehmite adsorbent was tested in a lab- scale fixed-bed reaction system. X-ray diffractograms （XRD） were used to characterize the adsorbent samp...The thiophene removal ability of the synthesized ZnNi/diatomite-pseudo-boehmite adsorbent was tested in a lab- scale fixed-bed reaction system. X-ray diffractograms （XRD） were used to characterize the adsorbent samples. The effects of Zn/Ni molar ratio, various model fuels and regeneration patterns on the RADS tests were studied. The adsorption mecha- nism was investigated by XRD and MS analyses. The results indicted that thiophene in the model fuel was first decomposed on the surface Ni of the adsorbent to form Ni3S2 while the hydrocarbon portion of the molecule was released back into the process stream, followed by reduction of Ni3S2 to form H2S in the presence of H2, and then HzS is stored in the adsorbent accompanied by the conversion of ZnO into ZnS.展开更多
Aiming to improve the reactive adsorption desulfurization（RADS） performances of Ni/Zn O adsorbents,ZnxAly（OH）2（CO3）z·x H2 O precursor is synthesized by coprecipitation of Zn2＋,AlO-2,and CO2-3; the Zn OZn6A...Aiming to improve the reactive adsorption desulfurization（RADS） performances of Ni/Zn O adsorbents,ZnxAly（OH）2（CO3）z·x H2 O precursor is synthesized by coprecipitation of Zn2＋,AlO-2,and CO2-3; the Zn OZn6Al2O9 composite oxides are obtained by the calcination of ZnxAly（OH）2（CO3）z·x H2 O precursor,and the Ni/Zn O-Zn6Al2O9（6.0 wt% Ni O） adsorbents are prepared by wetness impregnation method. The phase,acid strength,acid type and quantity,morphology,and thermal properties were characterized by X-ray diffraction,temperature-programmed desorption of ammonia,pyridine-adsorbed infrared spectrum,high-resolution transmission electron microscopy,and Thermo Gravimetry-Derivative Thermo Gravimetry（TG-DTG）,respectively. The breakthrough sulfur capacities of six adsorbents are between 34.2 and 47.9 mg/gcat. The kinetic studies indicated that the active energy of RADS（49.4 k J/mol） could reach nano-sized Zn O,the particle size of is about 12.0 nm. All the excellent RADS performances can be due to the high SBET. Also,there are some extents of aromatization reactions that occur,which can be contributed to the B？nsted acid rooted in Zn6Al2O9 composite oxide,and the octane number of products can be preserved well.展开更多
As well known in the petroleum industry and academia,Ni/ZnO catalysts have excellent desulfurization performance.However,the sulfur transfer mechanism of reactive adsorption desulfurization(RADS)that occurs on Ni/ZnO ...As well known in the petroleum industry and academia,Ni/ZnO catalysts have excellent desulfurization performance.However,the sulfur transfer mechanism of reactive adsorption desulfurization(RADS)that occurs on Ni/ZnO catalysts remains controversial.Herein,a periodic Ni nanorod supported on ZnO slab was built to represent the Ni/ZnO system,and density functional theory calculations were performed to study the sulfur transfer process and the role of H_(2)within the process.The results elucidate that the direct solid-state diffusion of S from Ni to interfacial oxygen vacancies(Ov)is more favorable than the hydrogenation of S to SH/H_(2)S on Ni and the subsequent H_(2)S desorption,and accordingly,H_(2)O is produced on Ni rather than on ZnO.Ab initio thermodynamics analysis shows that the hydrogen atmosphere applied in preparing Ni/ZnO catalysts greatly promotes the O_(v)formation on ZnO surface,which accounts for the presence of interfacial O_(v)in freshly prepared catalysts.Under RADS condition,hydrogenation of interfacial O atoms to form O-H groups facilitates the reverse spillover of these lattice O atoms from ZnO to Ni,accompanied with the interfacial O_(v)generation.In contrast to the classic S transfer mechanism via H_(2)S,the present work clearly demonstrates that the interfacial S transfer is a feasible reaction pathway in the RADS mechanism.More importantly,the existence of interfacial O_(v)is an essential prerequisite for this interfacial S diffusion,and H_(2)plays a key role in facilitating the O_(v)formation.展开更多
The thiophene removal ability of the synthesized NiZnO-based adsorbent was tested in a lab-scale fixed-bed system. The X-ray diffractometer (XRD) and the temperature-programmed reduction (H2-TPR) instrument were used ...The thiophene removal ability of the synthesized NiZnO-based adsorbent was tested in a lab-scale fixed-bed system. The X-ray diffractometer (XRD) and the temperature-programmed reduction (H2-TPR) instrument were used to characterize the samples. The XRD and TPR results showed that there existed stronger synergetic effect between ZnO and NiO to form well-dispersed adsorbent particles when the Zn/Ni molar ratio in adsorbent was 0.4, and that the optimum temperature for reduction of the NiZnO-based adsorbent was approximately in the range of 350℃—400℃. In addition, the effects of reaction temperature, and reaction pressure on the reactive adsorption desulfurization tests were studied.展开更多
The effect of mixed oxide support on the performance of Ni/ZnO in the reactive adsorption desulfurization(RADS) reaction was investigated in a fixed bed reactor by using thiophene as the sulfur-containing compound in ...The effect of mixed oxide support on the performance of Ni/ZnO in the reactive adsorption desulfurization(RADS) reaction was investigated in a fixed bed reactor by using thiophene as the sulfur-containing compound in the model gasoline. A series of oxide supports for Ni/ZnO were synthesized by the co-precipitation method and characterized by XRD, N_2-adsorption, TPR and NH_3-TPD techniques. It was found that the desulfurization capacity of Ni/ZnO was enhanced greatly when active components were supported on the proper mixed oxide. Ni/ZnO supported on oxides exhibited much higher desulfurization efficiency and sulfur adsorption capacity than the unsupported Ni/ZnO and the synthesized Ni/ZnO-SA adsorbent exhibited the highest efficiency for thiophene removal. The higher desulfurization activity and sulfur capacity of Ni/ZnO supported on SiO_2-Al_2O_3 with small particle size, high specific surface area and large pore volume could promote the high dispersion of active metal phase and the transfer of sulfur to ZnO with lower mass transfer resistance. γ-Al_2O_3 species could weaken the interaction of active phases and SiO_2 as well as could increase greatly the amount of weak acids. Therefore, these oxides could impose a great influence on the structure and chemical properties of the catalyst.展开更多
To investigate the effect of texture structure on the desulfurization performance in the Ni/ZnO reactive adsorption desulfurization（RADS） system,two kinds of ZnO porous materials with rod-shaped morphology were synt...To investigate the effect of texture structure on the desulfurization performance in the Ni/ZnO reactive adsorption desulfurization（RADS） system,two kinds of ZnO porous materials with rod-shaped morphology were synthesized and their structure was characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,and N2 adsorption/desorption.The formation mechanisms of hierarchical porous ZnO（ZnO with meso and macro pores） were also studied.Their application performance was evaluated in the RADS process over Ni/ZnO absorbent.Due to the difference in structure between the two kinds of ZnO,the two ZnO based adsorbents showed different desulfurization activity.展开更多
In this study,a clew-like ZnO superstructure was synthesized by a copolymer-controlled self-assembly homogeneous precipitation method.Ni was impregnated to the clew-like ZnO superstructure to obtain Ni/ZnO adsorbents....In this study,a clew-like ZnO superstructure was synthesized by a copolymer-controlled self-assembly homogeneous precipitation method.Ni was impregnated to the clew-like ZnO superstructure to obtain Ni/ZnO adsorbents.The synthesized materials were characterized by scanning electron microscopy,transmission electron microscopy,N_2 sorption,X-ray diffraction,Fourier transform infrared spectrometry,and H2-temperature programmed reduction techniques.The reactive adsorption desulfurization(RADS)performance of the adsorbents was evaluated in a fixed bed reactor using thiophene in n-octane as a model fuel.Sample Ni/ZnO-4h exhibits a remarkably high performance with a sulfur capacity of 189.1 mg S g^(-1),which is above 6 times that of the one prepared with commercial ZnO.Characterization results show that the morphology changes from micro-clews to large solid sticks with the increase of the crystallization time.The loose and open architecture of the clew-like ZnO superstructure facilitates the diffusion of reactants/products,and prevents the adsorbent particles from breakage by supplying space for the volume expansion during the RADS process.The small nanoparticles in ZnO nanostrips result in a high sulfur adsorption capacity and also favor the dispersion of Ni,leading to an excellent RADS performance.展开更多
A high-performance Ni/ZnO adsorbent was prepared by homogeneous precipitation using urea hydro- lysis and characterized by N2 adsorption-desorption, X-ray diffraction （XRD）, and scanning electron microscope （SEM）....A high-performance Ni/ZnO adsorbent was prepared by homogeneous precipitation using urea hydro- lysis and characterized by N2 adsorption-desorption, X-ray diffraction （XRD）, and scanning electron microscope （SEM）. The adsorbent was applied to the deep desulfur- ization of gasoline and showed a high breakthrough sulful capacity and a remarkably high volume hourly space velocity. The effects of coexisting olefins in gasoline as well as adsorptive conditions on the adsorptive perfor- mance were examined. It was found that olefins in gasoline had a slightly inhibiting effect on the desulfurization performance of the adsorbent. The optimum conditions were 673 K, 1.0 Mpa with a volume hourly space velocity of 60h^-1. Under the optimum conditions, ultralow sulfur gasoline could be produced and the breakthrough sulfur capacity of the adsorbent was 360 mg-s/g-sorb for the model gasoline.展开更多
The reactive adsorption desulfurization of model gasoline was carried out on Ni/ZnO-HY adsorbent.The Ni/ZnO-HY adsorbent was characterized by N2adsorption-desorption test(BET),X-ray diffractometry(XRD),and temperature...The reactive adsorption desulfurization of model gasoline was carried out on Ni/ZnO-HY adsorbent.The Ni/ZnO-HY adsorbent was characterized by N2adsorption-desorption test(BET),X-ray diffractometry(XRD),and temperature-programmed reduction(TPR)analysis.The test results have demonstrated that HY-zeolite is a feasible support for Ni/ZnO components used in reactive adsorption desulfurization.The results of XRD and TPR analyses showed that most of nickel element was present as Ni2+species with only a small part existing as Ni3+species,and the Ni2+species had interactions with HY-zeolite.Under the conditions of this study,which specified a 50% ratio of HY-zeolite in the adsorbent,a Zn/Ni molar ratio of 10,and a reduction temperature of 400℃,the Ni/ZnO-HY adsorbent showed the best desulfurization performance.The sulfur capacity of Ni/ZnO-HY adsorbent could be recovered to 92.19% of the fresh one after being subjected to regeneration at 500℃,and could be maintained at 82.17% of the fresh one after 5 regeneration cycles.展开更多
Adsorption is an important process in wastewater treatment,and conversion of waste materials to adsorbent offers a solution to high material cost related to the use of commercial activated carbon.This study investigat...Adsorption is an important process in wastewater treatment,and conversion of waste materials to adsorbent offers a solution to high material cost related to the use of commercial activated carbon.This study investigated the adsorption behaviour of Reactive Black 5（RB5）and methylene blue（MB）onto activated carbon produced from textile sludge（TSAC）.The activated carbon was synthesized through chemical activation of precursor followed with carbonization at 650℃ under nitrogen flow.Effects of time（0–200 min）,pH（2–10）,temperature（25–60℃）,initial dye concentration（0–200 mg·L^-1）,and adsorbent dosage（0.01–0.15 g）on dye removal efficiency were investigated.Preliminary screening revealed that TSAC synthesized via H2SO4activation showed higher adsorption behaviour than TSAC activated by KCl and ZnCl2.The adsorption capacity of TSAC was found to be 11.98 mg·g^-1（RB5）and 13.27 mg·g^-1（MB）,and is dependent on adsorption time and initial dye concentration.The adsorption data for both dyes were well fitted to Freundlich isotherm model which explains the heterogeneous nature of TSAC surface.The dye adsorption obeyed pseudo-second order kinetic model,thus chemisorption was the controlling step.This study reveals potential of textile sludge in removal of dyes from aqueous solution,and further studies are required to establish the applicability of the synthesized adsorbent for the treatment of waste water containing toxic dyes from textile industry.展开更多
The adsorption behavior of folic acid onto（5,0） zigzag and（5,5） armchair carbon nanotube（SWCNT） has been investigated using B3 LYP density functional at the 6-31G＊ level. The adsorption energies,molecular orbit...The adsorption behavior of folic acid onto（5,0） zigzag and（5,5） armchair carbon nanotube（SWCNT） has been investigated using B3 LYP density functional at the 6-31G＊ level. The adsorption energies,molecular orbital analysis and structural changes at the adsorption site are indicative of covalent adsorption on the zigzag SWCNT surface,while the adsorption is physical on the armchair SWCNT surface. The density of states（DOS） Plot and the quantum molecular descriptors（QMD） are witness to the significant changes in the electronic properties of SWCNT systems after the attachment of adsorbed species to the tube surface. According to the calculated results,the single-walled carbon nanotubes are expected to be a potential efficient adsorbent for the adsorption of folic acid drug and also can be used as a suitable drug delivery vehicle within biological systems.展开更多
Dyes often include toxic, carcinogenic compounds and are harmful to humans＇ health. Therefore, removal of dyes from textile industw wastewater is essential. The present study aimed to evaluate the efficiency of the c...Dyes often include toxic, carcinogenic compounds and are harmful to humans＇ health. Therefore, removal of dyes from textile industw wastewater is essential. The present study aimed to evaluate the efficiency of the combination of zero valent iron （ZVI） powder and multi-walled carbon nanotubes （MWCNTs） in the removal of Reactive Red 198 （RR198） dye from aqueous solution. This applied research was performed in a batch system in the laboratory scale. This study investigated the effect of various factors influencing dye removal, including contact time, pH, adsorbent dose, iron powder dose, initial dye concentration, and temperature. The equilibrium adsorption data were analyzed using three common adsorption models： Langmuir, Freundlich and Temkin. Besides, kinetic and thermodynamic parameters were used to establish the adsorption mechanism. The results showed, in pH = 3, contact time = 100 min, ZVI dose = 5000 mg· L- 1, and MWCNTs dose = 600 mg· L- 1 in 100 mg· L- 1 dye concentration, the adsorption efficiency increased to 99.16%. Also, adsorption kinetics was best described by the pseudo-second-order model. Equilibrium data fitted well with the Freundlich isotherm （R2 = 0.99）. The negative values of AGo and the positive value of △H0 （91.76） indicate that the RR198 adsorption process is spontaneous and endothermic. According to the results, the combination of MWCNTs and ZVI was highly efficient in the removal of azo dyes.展开更多
The waste gas evolved from biodegradation of animal urine contains ammonia causing environmental concerns. A new and effective method for removing ammonia from such waste gas using reactive adsorption is presented. In...The waste gas evolved from biodegradation of animal urine contains ammonia causing environmental concerns. A new and effective method for removing ammonia from such waste gas using reactive adsorption is presented. In the process, activated carbon impregnated with H2SO4（H2SO4/C） is employed. Ammonia in the waste gas reacts with H2SO4 on the adsorbent instantaneously and completely to form （NIL）2SO4. The H2SO4/C adsorbent is high in NH3 adsorption capacity and regenerable. The NH3 removal capacity of this regenerable adsorbent is more than 30 times that of the adsorbents used normally in the industry. The spent H2SO4/C is regenerated by flowing low-pressure steam through the adsorbent bed to remove the （NH4）2SO4 from the adsorbent. The regeneration by-product is concentrated （NH4）2SO4 solution, which is a perfect liquid fertilizer for local use. Re-soaking the activated carbon with H2SO4 solution rejuvenates the activity of the adsorbent. Thus the H2SOJC can be reused repeatedly. In the mechanism of this reactive adsorption process, trace of H20 in the waste gas is a required, which lends itself to treating ammonia gas saturated with moisture from biodegradation of animal urine.展开更多
A Cu-Co-K/activated carbon （AC） adsorbent has been developed for the removal of carbonyl sulfide （COS）. The effects of COS concentration, reaction temperature and relative humidity were closely examined. A breakth...A Cu-Co-K/activated carbon （AC） adsorbent has been developed for the removal of carbonyl sulfide （COS）. The effects of COS concentration, reaction temperature and relative humidity were closely examined. A breakthrough of 33.23 mg COS .gl adsorbent at 60℃, under 30% relative humidity and in presence of 1.0% oxygen was exhibited in the Cu-Co-K/AC adsorbent prepared. Competitive adsorption studies for COS in the presence of CS2, and H2S were also conducted. TPD analysis was used to identify sulfur-containing products on the carbon surface, and the results indicated that H2S, COS and SO2 were all evident in the effluent gas generated from the exhausted Cu-Co-K/AC. Structure of the activated carbon samples has been characterized using nitrogen adsorption, and their surface chemical structures were also determined with X-ray photoelectron spectroscopy （XPS）. It turns out that the modification with Cu（OH）2CO3- CoPcS-KOH can significantly improve the COS removal capacity, forming SO2/4 species simultaneously. Regenera- tion of the spent activated carbon sorbents by thermal desorption has also been explored.展开更多
基金supported by National Key Fundamental Research development Plan ("973" Plan, No. 2010CB226905)the Postgraduate Innovation Fund of China University of petroleumthe Postgraduate Innovation Fund of China University of petroleum
文摘To better understand the nature of reactive adsorption of thiophene on Ni/ZnO adsorbent,the effect of ZnO textural structure on the desulfurization activity was investigated.ZnO materials were synthesized by low-temperature solid-state reaction and the corresponding Ni/ZnO adsorbents were prepared by incipient impregnation method.The analysis results showed that the crystalline sizes of ZnO as-synthesized as well as the BET surface areas varied obviously with the calcination temperature.The activity evaluations indicated that the Ni/ZnO adsorbents prepared with ZnO possessed a favorable textural structure as active component exhibited good activity of removing thiophene.The evolutions of the main crystalline phases of Ni/ZnO adsorbents before and after reaction confirmed that ZnO played a crucial role in taking up S element and converting it into ZnS in the reactive adsorption process.It was concluded that ZnO with larger surface area and smaller crystal particles resulted in better desulfurization activity,which may be the main reason for the different activities of the Ni/ZnO adsorbents prepared with ZnO calcined at different temperatures.
文摘The thiophene removal ability of the synthesized ZnNi/diatomite-pseudo-boehmite adsorbent was tested in a lab- scale fixed-bed reaction system. X-ray diffractograms （XRD） were used to characterize the adsorbent samples. The effects of Zn/Ni molar ratio, various model fuels and regeneration patterns on the RADS tests were studied. The adsorption mecha- nism was investigated by XRD and MS analyses. The results indicted that thiophene in the model fuel was first decomposed on the surface Ni of the adsorbent to form Ni3S2 while the hydrocarbon portion of the molecule was released back into the process stream, followed by reduction of Ni3S2 to form H2S in the presence of H2, and then HzS is stored in the adsorbent accompanied by the conversion of ZnO into ZnS.
文摘Aiming to improve the reactive adsorption desulfurization（RADS） performances of Ni/Zn O adsorbents,ZnxAly（OH）2（CO3）z·x H2 O precursor is synthesized by coprecipitation of Zn2＋,AlO-2,and CO2-3; the Zn OZn6Al2O9 composite oxides are obtained by the calcination of ZnxAly（OH）2（CO3）z·x H2 O precursor,and the Ni/Zn O-Zn6Al2O9（6.0 wt% Ni O） adsorbents are prepared by wetness impregnation method. The phase,acid strength,acid type and quantity,morphology,and thermal properties were characterized by X-ray diffraction,temperature-programmed desorption of ammonia,pyridine-adsorbed infrared spectrum,high-resolution transmission electron microscopy,and Thermo Gravimetry-Derivative Thermo Gravimetry（TG-DTG）,respectively. The breakthrough sulfur capacities of six adsorbents are between 34.2 and 47.9 mg/gcat. The kinetic studies indicated that the active energy of RADS（49.4 k J/mol） could reach nano-sized Zn O,the particle size of is about 12.0 nm. All the excellent RADS performances can be due to the high SBET. Also,there are some extents of aromatization reactions that occur,which can be contributed to the B？nsted acid rooted in Zn6Al2O9 composite oxide,and the octane number of products can be preserved well.
基金supported by the National Natural Science Foundation of China(22178388,21776315)the Taishan Scholars Program of Shandong Province(tsqn201909065)the Fundamental Research Funds for the Central Universities(19CX05001A).
文摘As well known in the petroleum industry and academia,Ni/ZnO catalysts have excellent desulfurization performance.However,the sulfur transfer mechanism of reactive adsorption desulfurization(RADS)that occurs on Ni/ZnO catalysts remains controversial.Herein,a periodic Ni nanorod supported on ZnO slab was built to represent the Ni/ZnO system,and density functional theory calculations were performed to study the sulfur transfer process and the role of H_(2)within the process.The results elucidate that the direct solid-state diffusion of S from Ni to interfacial oxygen vacancies(Ov)is more favorable than the hydrogenation of S to SH/H_(2)S on Ni and the subsequent H_(2)S desorption,and accordingly,H_(2)O is produced on Ni rather than on ZnO.Ab initio thermodynamics analysis shows that the hydrogen atmosphere applied in preparing Ni/ZnO catalysts greatly promotes the O_(v)formation on ZnO surface,which accounts for the presence of interfacial O_(v)in freshly prepared catalysts.Under RADS condition,hydrogenation of interfacial O atoms to form O-H groups facilitates the reverse spillover of these lattice O atoms from ZnO to Ni,accompanied with the interfacial O_(v)generation.In contrast to the classic S transfer mechanism via H_(2)S,the present work clearly demonstrates that the interfacial S transfer is a feasible reaction pathway in the RADS mechanism.More importantly,the existence of interfacial O_(v)is an essential prerequisite for this interfacial S diffusion,and H_(2)plays a key role in facilitating the O_(v)formation.
文摘The thiophene removal ability of the synthesized NiZnO-based adsorbent was tested in a lab-scale fixed-bed system. The X-ray diffractometer (XRD) and the temperature-programmed reduction (H2-TPR) instrument were used to characterize the samples. The XRD and TPR results showed that there existed stronger synergetic effect between ZnO and NiO to form well-dispersed adsorbent particles when the Zn/Ni molar ratio in adsorbent was 0.4, and that the optimum temperature for reduction of the NiZnO-based adsorbent was approximately in the range of 350℃—400℃. In addition, the effects of reaction temperature, and reaction pressure on the reactive adsorption desulfurization tests were studied.
基金financially supported by the National Natural Science Foundation of China(No.21276086)
文摘The effect of mixed oxide support on the performance of Ni/ZnO in the reactive adsorption desulfurization(RADS) reaction was investigated in a fixed bed reactor by using thiophene as the sulfur-containing compound in the model gasoline. A series of oxide supports for Ni/ZnO were synthesized by the co-precipitation method and characterized by XRD, N_2-adsorption, TPR and NH_3-TPD techniques. It was found that the desulfurization capacity of Ni/ZnO was enhanced greatly when active components were supported on the proper mixed oxide. Ni/ZnO supported on oxides exhibited much higher desulfurization efficiency and sulfur adsorption capacity than the unsupported Ni/ZnO and the synthesized Ni/ZnO-SA adsorbent exhibited the highest efficiency for thiophene removal. The higher desulfurization activity and sulfur capacity of Ni/ZnO supported on SiO_2-Al_2O_3 with small particle size, high specific surface area and large pore volume could promote the high dispersion of active metal phase and the transfer of sulfur to ZnO with lower mass transfer resistance. γ-Al_2O_3 species could weaken the interaction of active phases and SiO_2 as well as could increase greatly the amount of weak acids. Therefore, these oxides could impose a great influence on the structure and chemical properties of the catalyst.
基金Financial support from the National Basic Research Program of China (No. 2010CB226905)the National Natural Science Foundation of China (Nos. 21176258, U1162203)the Specialized Research Fund for the Doctoral Program of Higher Education (20110133110002)
文摘To investigate the effect of texture structure on the desulfurization performance in the Ni/ZnO reactive adsorption desulfurization（RADS） system,two kinds of ZnO porous materials with rod-shaped morphology were synthesized and their structure was characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,and N2 adsorption/desorption.The formation mechanisms of hierarchical porous ZnO（ZnO with meso and macro pores） were also studied.Their application performance was evaluated in the RADS process over Ni/ZnO absorbent.Due to the difference in structure between the two kinds of ZnO,the two ZnO based adsorbents showed different desulfurization activity.
基金supported by the Joint Funds of the National Natural Science Foundation of China and China National Petroleum Corporation(U1362202)the National Natural Science Foundation of China(51601223 and 21206195)+2 种基金the Fundamental Research Funds for the Central Universities(17CX05018,17CX02056 and YCX2017039)Shandong Provincial Natural Science Foundation(ZR2012BM014)the project sponsored by Scientific Research Foundation for Returned Overseas Chinese Scholars
文摘In this study,a clew-like ZnO superstructure was synthesized by a copolymer-controlled self-assembly homogeneous precipitation method.Ni was impregnated to the clew-like ZnO superstructure to obtain Ni/ZnO adsorbents.The synthesized materials were characterized by scanning electron microscopy,transmission electron microscopy,N_2 sorption,X-ray diffraction,Fourier transform infrared spectrometry,and H2-temperature programmed reduction techniques.The reactive adsorption desulfurization(RADS)performance of the adsorbents was evaluated in a fixed bed reactor using thiophene in n-octane as a model fuel.Sample Ni/ZnO-4h exhibits a remarkably high performance with a sulfur capacity of 189.1 mg S g^(-1),which is above 6 times that of the one prepared with commercial ZnO.Characterization results show that the morphology changes from micro-clews to large solid sticks with the increase of the crystallization time.The loose and open architecture of the clew-like ZnO superstructure facilitates the diffusion of reactants/products,and prevents the adsorbent particles from breakage by supplying space for the volume expansion during the RADS process.The small nanoparticles in ZnO nanostrips result in a high sulfur adsorption capacity and also favor the dispersion of Ni,leading to an excellent RADS performance.
文摘A high-performance Ni/ZnO adsorbent was prepared by homogeneous precipitation using urea hydro- lysis and characterized by N2 adsorption-desorption, X-ray diffraction （XRD）, and scanning electron microscope （SEM）. The adsorbent was applied to the deep desulfur- ization of gasoline and showed a high breakthrough sulful capacity and a remarkably high volume hourly space velocity. The effects of coexisting olefins in gasoline as well as adsorptive conditions on the adsorptive perfor- mance were examined. It was found that olefins in gasoline had a slightly inhibiting effect on the desulfurization performance of the adsorbent. The optimum conditions were 673 K, 1.0 Mpa with a volume hourly space velocity of 60h^-1. Under the optimum conditions, ultralow sulfur gasoline could be produced and the breakthrough sulfur capacity of the adsorbent was 360 mg-s/g-sorb for the model gasoline.
基金financially supported by the National Natural Science Foundation of China(No.21276086)the Opening Project of State Key Laboratory of Chemical Engineering of East China University of Science and Technology(No.SKL-ChE-11C04)
文摘The reactive adsorption desulfurization of model gasoline was carried out on Ni/ZnO-HY adsorbent.The Ni/ZnO-HY adsorbent was characterized by N2adsorption-desorption test(BET),X-ray diffractometry(XRD),and temperature-programmed reduction(TPR)analysis.The test results have demonstrated that HY-zeolite is a feasible support for Ni/ZnO components used in reactive adsorption desulfurization.The results of XRD and TPR analyses showed that most of nickel element was present as Ni2+species with only a small part existing as Ni3+species,and the Ni2+species had interactions with HY-zeolite.Under the conditions of this study,which specified a 50% ratio of HY-zeolite in the adsorbent,a Zn/Ni molar ratio of 10,and a reduction temperature of 400℃,the Ni/ZnO-HY adsorbent showed the best desulfurization performance.The sulfur capacity of Ni/ZnO-HY adsorbent could be recovered to 92.19% of the fresh one after being subjected to regeneration at 500℃,and could be maintained at 82.17% of the fresh one after 5 regeneration cycles.
基金the Ministry of Higher Education,Malaysia(MOHE)for the financial supports received under University Grant(08H05)and Fundamental Research Grant Scheme(4F872)Universiti Teknologi Malaysia for the GUP grant No.17H65the support to the main author,Wong Syie Luing,in the form of Post-Doctoral Fellowship Scheme for the project"Catalytic Cracking of Low Density Polyethylene Waste to Liquid Fuels in Fixed Bed Reactor"
文摘Adsorption is an important process in wastewater treatment,and conversion of waste materials to adsorbent offers a solution to high material cost related to the use of commercial activated carbon.This study investigated the adsorption behaviour of Reactive Black 5（RB5）and methylene blue（MB）onto activated carbon produced from textile sludge（TSAC）.The activated carbon was synthesized through chemical activation of precursor followed with carbonization at 650℃ under nitrogen flow.Effects of time（0–200 min）,pH（2–10）,temperature（25–60℃）,initial dye concentration（0–200 mg·L^-1）,and adsorbent dosage（0.01–0.15 g）on dye removal efficiency were investigated.Preliminary screening revealed that TSAC synthesized via H2SO4activation showed higher adsorption behaviour than TSAC activated by KCl and ZnCl2.The adsorption capacity of TSAC was found to be 11.98 mg·g^-1（RB5）and 13.27 mg·g^-1（MB）,and is dependent on adsorption time and initial dye concentration.The adsorption data for both dyes were well fitted to Freundlich isotherm model which explains the heterogeneous nature of TSAC surface.The dye adsorption obeyed pseudo-second order kinetic model,thus chemisorption was the controlling step.This study reveals potential of textile sludge in removal of dyes from aqueous solution,and further studies are required to establish the applicability of the synthesized adsorbent for the treatment of waste water containing toxic dyes from textile industry.
文摘The adsorption behavior of folic acid onto（5,0） zigzag and（5,5） armchair carbon nanotube（SWCNT） has been investigated using B3 LYP density functional at the 6-31G＊ level. The adsorption energies,molecular orbital analysis and structural changes at the adsorption site are indicative of covalent adsorption on the zigzag SWCNT surface,while the adsorption is physical on the armchair SWCNT surface. The density of states（DOS） Plot and the quantum molecular descriptors（QMD） are witness to the significant changes in the electronic properties of SWCNT systems after the attachment of adsorbed species to the tube surface. According to the calculated results,the single-walled carbon nanotubes are expected to be a potential efficient adsorbent for the adsorption of folic acid drug and also can be used as a suitable drug delivery vehicle within biological systems.
文摘Dyes often include toxic, carcinogenic compounds and are harmful to humans＇ health. Therefore, removal of dyes from textile industw wastewater is essential. The present study aimed to evaluate the efficiency of the combination of zero valent iron （ZVI） powder and multi-walled carbon nanotubes （MWCNTs） in the removal of Reactive Red 198 （RR198） dye from aqueous solution. This applied research was performed in a batch system in the laboratory scale. This study investigated the effect of various factors influencing dye removal, including contact time, pH, adsorbent dose, iron powder dose, initial dye concentration, and temperature. The equilibrium adsorption data were analyzed using three common adsorption models： Langmuir, Freundlich and Temkin. Besides, kinetic and thermodynamic parameters were used to establish the adsorption mechanism. The results showed, in pH = 3, contact time = 100 min, ZVI dose = 5000 mg· L- 1, and MWCNTs dose = 600 mg· L- 1 in 100 mg· L- 1 dye concentration, the adsorption efficiency increased to 99.16%. Also, adsorption kinetics was best described by the pseudo-second-order model. Equilibrium data fitted well with the Freundlich isotherm （R2 = 0.99）. The negative values of AGo and the positive value of △H0 （91.76） indicate that the RR198 adsorption process is spontaneous and endothermic. According to the results, the combination of MWCNTs and ZVI was highly efficient in the removal of azo dyes.
文摘The waste gas evolved from biodegradation of animal urine contains ammonia causing environmental concerns. A new and effective method for removing ammonia from such waste gas using reactive adsorption is presented. In the process, activated carbon impregnated with H2SO4（H2SO4/C） is employed. Ammonia in the waste gas reacts with H2SO4 on the adsorbent instantaneously and completely to form （NIL）2SO4. The H2SO4/C adsorbent is high in NH3 adsorption capacity and regenerable. The NH3 removal capacity of this regenerable adsorbent is more than 30 times that of the adsorbents used normally in the industry. The spent H2SO4/C is regenerated by flowing low-pressure steam through the adsorbent bed to remove the （NH4）2SO4 from the adsorbent. The regeneration by-product is concentrated （NH4）2SO4 solution, which is a perfect liquid fertilizer for local use. Re-soaking the activated carbon with H2SO4 solution rejuvenates the activity of the adsorbent. Thus the H2SOJC can be reused repeatedly. In the mechanism of this reactive adsorption process, trace of H20 in the waste gas is a required, which lends itself to treating ammonia gas saturated with moisture from biodegradation of animal urine.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. Ul137603, 51268021 and 51368026）, the National High Technology Research and Development Program of China （No. 2012AA062504） and the Applied Basic Research Program of Yunnan （Nos. 2011FB027 and 2011FA010）.
文摘A Cu-Co-K/activated carbon （AC） adsorbent has been developed for the removal of carbonyl sulfide （COS）. The effects of COS concentration, reaction temperature and relative humidity were closely examined. A breakthrough of 33.23 mg COS .gl adsorbent at 60℃, under 30% relative humidity and in presence of 1.0% oxygen was exhibited in the Cu-Co-K/AC adsorbent prepared. Competitive adsorption studies for COS in the presence of CS2, and H2S were also conducted. TPD analysis was used to identify sulfur-containing products on the carbon surface, and the results indicated that H2S, COS and SO2 were all evident in the effluent gas generated from the exhausted Cu-Co-K/AC. Structure of the activated carbon samples has been characterized using nitrogen adsorption, and their surface chemical structures were also determined with X-ray photoelectron spectroscopy （XPS）. It turns out that the modification with Cu（OH）2CO3- CoPcS-KOH can significantly improve the COS removal capacity, forming SO2/4 species simultaneously. Regenera- tion of the spent activated carbon sorbents by thermal desorption has also been explored.
