期刊文献+
共找到64篇文章
< 1 2 4 >
每页显示 20 50 100
Removal of Organochlorine from Model Oil Using Mg-Modified ZSM-5 Zeolite:Dechlorination Performance,Regeneration,and Thermodynamics 被引量:1
1
作者 Cheng Xingyuan Gu Jie +4 位作者 Huang Bingtian Bing Liancheng Han Dezhi Wang Guangjian Wang Fang 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS CSCD 2023年第2期24-32,共9页
Various metal-modified ZSM-5 zeolite adsorbents prepared by the impregnation method were applied to the removal of organic chlorides from model naphtha.The adsorption performance and regeneration stability were invest... Various metal-modified ZSM-5 zeolite adsorbents prepared by the impregnation method were applied to the removal of organic chlorides from model naphtha.The adsorption performance and regeneration stability were investigated by static adsorption experiments.The morphologies,structural features,and physicochemical properties of the adsorbents were characterized by X-ray diffraction,Brunauer-Emmett-Teller analysis,NH3 temperature-programmed desorption,scanning electron microscopy,transmission electron microscopy,and pyridine adsorption infrared spectroscopy.The Mg/ZSM-5 zeolite adsorbent possessed a relatively high specific surface area and good metal dispersion and exhibited the best dechlorination and regeneration performance.The characterization results revealed that introduction of the metal exerted a significant influence on the acidic properties of the catalyst surface.A decrease in the ratio of Brønsted acidic sites to Lewis acidic sites and an increase in the amount of moderately acidic sites were confirmed to be responsible for the excellent adsorption performance of the Mg-modified ZSM-5 zeolite.Furthermore,the Langmuir adsorption isotherm model was applied to study the adsorption equilibrium and thermodynamics of the Mg/ZSM-5 adsorbent under mild conditions.The results revealed that the removal of 1,2-dichloroethane by the Mg/ZSM-5 adsorbent was endothermic,spontaneous,disordered,and primarily involved physical adsorption. 展开更多
关键词 adsorption dechlorination zsm-5 zeolite metal modification THERMODYNAMICS
下载PDF
Alkali-metal-modified ZSM-5 zeolites for improvement of catalytic dehydration of lactic acid to acrylic acid 被引量:8
2
作者 袁川 刘华彦 +3 位作者 张泽凯 卢晗锋 朱秋莲 陈银飞 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2015年第11期1861-1866,共6页
Various ZSM-5 zeolites modified with alkali metals (Li, Na, K, Rb, and Cs) were prepared using ion exchange. The catalysts were used to enhance the catalytic dehydration of lactic acid (LA) to acrylic acid (AA).... Various ZSM-5 zeolites modified with alkali metals (Li, Na, K, Rb, and Cs) were prepared using ion exchange. The catalysts were used to enhance the catalytic dehydration of lactic acid (LA) to acrylic acid (AA). The effects of cationic species on the structures and surface acid-base distributions of the ZSM-5 zeolites were investigated. The important factors that affect the catalytic performance were also identified. The modified ZSM-5 catalysts were characterized using X-ray diffraction, tempera- ture-programmed desorptions of NH3 and CO2, pyridine adsorption spectroscopy, and N2 adsorption to determine the crystal phase structures, surface acidities and basicities, nature of acid sites, specific surface areas, and pore volumes. The results show that the acid-base sites that are adjusted by alkali-metal species, particularly weak acid-base sites, are mainly responsible for the formation of AA. The KZSM-5 catalyst, in particular, significantly improved LA conversion and AA selectivity because of the synergistic effect of weak acid-base sites. The reaction was conducted at different reaction temperatures and liquid hourly space velocities (LHSVs) to understand the catalyst selectivity for AA and trends in byproduct formation. Approximately 98% LA conversion and 77% AA selectivity were achieved using the KZSM-5 catalyst under the optimum conditions (40 wt% LA aqueous solution, 365 ℃, and LHSV 2 h-1). 展开更多
关键词 zsm-5 zeolite Alkali metal Lactic acid Acrylic acid Dehydration
下载PDF
Aromatization over nanosized Ga-containing ZSM-5 zeolites prepared by different methods:Effect of acidity of active Ga species on the catalytic performance 被引量:10
3
作者 Yujun Fang Xiaofang Su +4 位作者 Xuefeng Bai Wei Wu Gaoliang Wang Linfei Xiao Anran Yu 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2017年第4期768-775,共8页
Nanosized Ga-containing ZSM-5 zeolites were prepared via isomorphous substitution and impregnation followed by characterized using various techniques. The catalytic performance of the zeolites for the aromatization of... Nanosized Ga-containing ZSM-5 zeolites were prepared via isomorphous substitution and impregnation followed by characterized using various techniques. The catalytic performance of the zeolites for the aromatization of 1-hexene was investigated. The results indicate that isomorphous substitution promotes the incorporation of Ga heteroatoms into the framework along with the formation of extra-framework GaO;species([GaO;]a) that have stronger interactions with the negative potential of the framework. In addition, based on the Py-IR results and catalytic performance, the [GaO;]aspecies with stronger Lewis acid sites produced a better synergism with moderate Br?nsted acid sites and thus improved the selectivity to aromatic compounds. However, the impregnation results in the formation of Ga;O;phase and small amounts of GaO;species that are mainly located on the external surface([GaO;];), which contribute to weaker Lewis acid sites due to weaker interactions with the zeolite framework. During 1-hexene aromatization, the nanosized Ga isomorphously substituted ZSM-5 zeolite samples(Gax-NZ5) exhibited better catalytic performance compared to the impregnated samples, and the highest aromatic yield(i.e.,65.4 wt%) was achieved over the Ga4.2-NZ5 sample, which contained with the highest Ga content. 展开更多
关键词 Nanosized zsm-5 zeolite Isomorphous substitution IMPREGNATION Active gallium species AROMATIZATION
下载PDF
Thermal and hydrothermal stabilities of the alkali-treated HZSM-5 zeolites 被引量:10
4
作者 Yuning Li Dong Liu +4 位作者 Shenglin Liu Wei Wang Sujuan Xie Xiangxue Zhu Longya Xu 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2008年第1期69-74,共6页
HZSM-5 zeolites with the micro-mesopore hierarchical porosity have been prepared by the post-synthesis of alkali-treatment, and their thermal and hydrothermal stabilities were studied using DTA, XRD, and NH3-TPD chara... HZSM-5 zeolites with the micro-mesopore hierarchical porosity have been prepared by the post-synthesis of alkali-treatment, and their thermal and hydrothermal stabilities were studied using DTA, XRD, and NH3-TPD characterization techniques. Compared to the unmodified zeolite, the thermal and hydrothermal stabilities of the alkali-treated ZSM-5 zeolites were slightly deteriorated because of the introduction of mesopores caused by the desilication. Nevertheless, the alkali-treated zeolite framework could be maintained until the temperature increased to 1175 ℃. 展开更多
关键词 zsm-5 zeolite alkali-treatment thermal stability hydrothermal stability
下载PDF
Experiment and Modeling of Pure and Binary Adsorption of n-Butane and Butene-1 on ZSM-5 Zeolites with Different Si/Al Ratios 被引量:6
5
作者 王斐 汪文川 +2 位作者 黄世萍 滕加伟 谢在库 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2007年第3期376-386,共11页
Four ZSM-5 zeolite catalysts with different Si/Al ratios for the catalytic cracking of C4 fractions to produce ethylene and propylene were prepared in this study.First,the adsorption isotherms of pure n-butane and but... Four ZSM-5 zeolite catalysts with different Si/Al ratios for the catalytic cracking of C4 fractions to produce ethylene and propylene were prepared in this study.First,the adsorption isotherms of pure n-butane and butene-1 and their mixtures on these catalysts at 300K and p=0—100kPa were measured using the intelligent gra- vimetric analyzer.The experimental results indicate that the presence of Al can significantly affect the adsorption of butene-1 than that of n-butane on ZSM-5 zeolites.Then,the double Langmuir(DL)model was applied to study the pure gas adsorption on ZSM-5 zeolites for pure n-butane and butene-1.By combining the DL model with the ideal adsorbed solution theory(IAST),the IAST-DL model was applied to model the butene-1(1)/n-butane(2)binary mixture adsorption on ZSM-5 zeolites with different Si/Al ratios.The calculated results are in good agreement with the experimental data,indicating that the IAST-DL model is effective for the present systems.Finally,the adsorp- tion over a wide range of variables was predicted at low pressure and 300K by the model proposed.It is found that the selectivity of butene-1 over n-butane increases linearly with the decrease of Si/Al ratio.A correlation between the selectivity and Si/Al ratio of the sample was proposed at 300K and p=0.08MPa. 展开更多
关键词 zsm-5 zeolite N-BUTANE BUTENE-1 -adsorption isotherm Si/Al ratio SELECTIVITY
下载PDF
A novel method for enhancing the stability of ZSM-5 zeolites used for catalytic cracking of LPG: Catalyst modification by dealumination and subsequent silicon loading 被引量:3
6
作者 Leyla Vafi Ramin Karimzadeh 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第4期628-635,共8页
Composite structures of ZSM‐5 zeolites were prepared by the synthesis of mesopores and mi‐cropores using carbon nanotubes as a template. Dealumination of mesopores was performed selec‐tively using trichloroacetic a... Composite structures of ZSM‐5 zeolites were prepared by the synthesis of mesopores and mi‐cropores using carbon nanotubes as a template. Dealumination of mesopores was performed selec‐tively using trichloroacetic acid, which could only diffuse into the mesopores and not the mi‐cropores owing to the size of the trichloroacetic acid molecules. Empty spaces are created in the catalyst as a result of removal of the Al atoms from the zeolite structure. If Si atoms fill the empty space, then the structure of the mesopores becomes similar to silicates, which do not have any cata‐lytic properties. Silicon containing solution was used to fill the empty spaces, and in doing so, a unique method was developed, by which silicon atoms can directly replace the extracted Al atoms from the mesopore structure. Therefore, by changing the geometry and properties of the mesopores and micropores, the amount of coke reduced from 14%for HZSM‐5 to 3%for the modified zeolite. 展开更多
关键词 MESOPORES Carbon nanotube zsm-5 zeolite DEALUMINATION Trichloroacetic acid
下载PDF
Exploring suitable ZSM-5/MCM-41 zeolites for catalytic cracking of n-dodecane: Effect of initial particle size and Si/Al ratio 被引量:2
7
作者 李国柱 刁振恒 +1 位作者 那金丹 王莅 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第10期1655-1661,共7页
In this study,various ZSM-5/MCM-41 micro/mesoporous zeolite composites have been prepared by alkalidesilication and surfactant-directed recrystallization of ZSM-5.The effects of particle size and Si/Al ratio of initia... In this study,various ZSM-5/MCM-41 micro/mesoporous zeolite composites have been prepared by alkalidesilication and surfactant-directed recrystallization of ZSM-5.The effects of particle size and Si/Al ratio of initial ZSM-5 zeolites on the structure and catalytic performance of ZSM-5/MCM-41 composites are studied.The results of XRD,TEM N_2-adsorption-desorption,NH_3-TPD and in situ FT-IR revealed that ordered hexagonal MCM-41 mesopores with 3-4 nm pore size were formed around ZSM-5 crystals,and the specific surface area and mesopore volume of composites increased with increasing the Si/Al ratio of initial ZSM-5.Catalytic cracking of n-dodecane(550℃,4 MPa) showed that the ZSM-5/MCM-41 composites obtained from the high Si/Al ratio and nano-sized initial ZSM-5 zeolites exhibited superior catalytic performance,with the improvement higher than 87%in the catalytic activities and 21%in the deactivation rate compared with untreated zeolites.This could be ascribed to their suitable pore structure,which enhanced the diffusion of reactant molecules in pores of catalysts. 展开更多
关键词 zsm-5/MCM-41 zeolitE DESILICATION RECRYSTALLIZATION Catalytic cracking
下载PDF
Seed-Assisted Synthesis and Catalytic Performance of Nano-sized ZSM-5 Aggregates in a One-Step Crystallization Process 被引量:2
8
作者 Ziyang Wang Yaquan Wang +8 位作者 Chao Sun Aijuan Zhao Cui Wang Xu Zhang Jingjing Zhao Taotao Zhao Wenrong Liu Jiaxin Lu Shuhui Wu 《Transactions of Tianjin University》 EI CAS 2020年第4期292-304,共13页
Hierarchical nano-sized ZSM-5 aggregates were successfully synthesized via a seed-assisted method in the presence of cetyltrimethylammonium bromide(CTAB)through a facile one-step crystallization process.Commercial ZSM... Hierarchical nano-sized ZSM-5 aggregates were successfully synthesized via a seed-assisted method in the presence of cetyltrimethylammonium bromide(CTAB)through a facile one-step crystallization process.Commercial ZSM-5 zeolites with a SiO2/Al2O3 ratio comparable to that of ZSM-5 products were treated with alkali and used as the seed particles.The influences of crystallization conditions were investigated,and the possible synthesis mechanism was proposed.ZSM-5 zeolites with diff erent amounts of CTAB added were characterized using many techniques and evaluated in toluene alkylation with methanol.The results showed that a trace amount of CTAB signifi cantly promoted the crystallization of ZSM-5 zeolite,with the morphology changing from hexagonal-shape crystals to uniform spherical aggregates.CTAB may act as the structure-directing agent and assemble the primary crystallites to generate hierarchical ZSM-5 aggregates.The ZSM-5 zeolite with the smallest primary particles of 50-80 nm exhibited large specific surface area,abundant mesopores,and the greatest microporosity.The hierarchical nano-sized ZSM-5 aggregate showed higher toluene conversion and a longer lifetime without compromising the selectivity to xylene and p-xylene in toluene alkylation with methanol. 展开更多
关键词 Hierarchical zsm-5 nano-sized aggregates Seed-assisted CTAB Toluene alkylation with methanol
下载PDF
The Difference between ZSM-5 Zeolites Manufactured from Various Synthesis Systems and Their Catalytic Performances 被引量:1
9
作者 Zhao Huanyu Liu Yunqi Liu Chunying Liu Chenguang (The College of Chemistry & Chemical Engineering,China University of Petroleum(East China) Key Laboratory of Catalysis,Shandong 257061) 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2005年第3期49-55,共7页
ZSM-5 zeolites with similar St/Al ratio were synthesized successfully using various templates [n- butylamine (BTA), tetrapropylammonium bromide (TPABr) and no template (NT)] under hydrothermal conditions, The sa... ZSM-5 zeolites with similar St/Al ratio were synthesized successfully using various templates [n- butylamine (BTA), tetrapropylammonium bromide (TPABr) and no template (NT)] under hydrothermal conditions, The samples were characterized by XRD, SEM, Py-IR and BET surface area measurements in order to understand the template eiTects and the differences between the ZSM-5 santples. The synthesis of ZSM-5 with organic templates was relatively easier than those with inorganic templates and withnut template. SEM results revealed that ZSM-5 synthesized with different templates had different morphologies in similar particle size. Toluene disproportiortation reaction was carried out over the catalyst samples to evaluate the catalytic properties. The results have shown that large crystals which have a correspondingly small external surface showed a high para-xylene selectivity, and the amount of C9^+ and C5^+ was much less than that obtained from zeolite with small crystals. 展开更多
关键词 zsm-5 zeolite toluene disproportion SYNTHESIS TEMPLATE
下载PDF
Pore Structure and Catalytic Performance of Steam-Dealuminated ZSM-5/Y Composite Zeolites
10
作者 GuoJintao ShenBaojian ChenHonglin 《Petroleum Science》 SCIE CAS CSCD 2005年第1期62-65,共4页
For investigating the effect of dealumination on the pore structure and catalytic performance, ZSM-5/Y composite zeolites synthesized in situ from NaY gel were dealuminated by steaming at different temperatures. XRD ... For investigating the effect of dealumination on the pore structure and catalytic performance, ZSM-5/Y composite zeolites synthesized in situ from NaY gel were dealuminated by steaming at different temperatures. XRD (X-ray diffraction) characterization indicates that the relative crystallinity of the composite zeolites decreases with the increase in Si/Al ratio after steaming. N2 adsorption-desorption suggests that more mesopores are formed while the BET (Brunauer, Emmett and Teller) specific surface area and the micropore specific surface area decrease as the temperature of steaming rises. Daqing heavy oil was used as feedstock to test the catalytic cracking activity of ZSM-5/Y composite zeolites. The experimental results of the catalytic cracking performance reveal that the distribution of products differs due to the different conditions of hydrothermal treatment. Further hydrothermal treatment leads to an increase in the yield of light oil, and a decrease in the yield of gas products and coke. 展开更多
关键词 zsm-5/Y composite zeolites steam treatment pore structure catalytic performance
下载PDF
Synthesis and characterization of an unusual snowflake-shaped ZSM-5 zeolite with high catalytic performance in the methanol to olefin reaction 被引量:15
11
作者 李静 刘粟侥 +3 位作者 张怀科 吕恩静 任鹏举 任杰 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第2期308-315,共8页
The ZSM-5 zeolite with an unusual snowflake-shaped morphology was hydrothermally synthesized for the first time,and compared with common ellipsoidal and boat-like shaped samples.These samples were characterized by N2 ... The ZSM-5 zeolite with an unusual snowflake-shaped morphology was hydrothermally synthesized for the first time,and compared with common ellipsoidal and boat-like shaped samples.These samples were characterized by N2 adsorption-desorption,X-ray fluorescence spectroscopy,scanning electron microscopy,X-ray diffraction,magic angle spinning nuclear magnetic resonance,temperature-programmed desorption of ammonia,and infrared spectroscopy of pyridine adsorption.The results suggest that the BET surface area and SiO2/Al2O3 ratio of these samples are similar,while the snowflake-shaped ZSM-5 zeolite possesses more of the(101) face,and distortion,dislocation,and asymmetry in the framework,resulting in a larger number of acid sites than the conventional samples.Catalysts for the methanol to olefin(MTO) reaction were prepared by loading Ca on the samples.The snowflake-shaped Ca/ZSM-5 zeolite exhibited excellent selectivity for total light olefin(72%) and propene(39%) in MTO.The catalytic performance influenced by the morphology can be mainly attributed to the snowflake-shaped ZSM-5 zeolite possessing distortion,dislocation,and asymmetry in the framework,and lower diffusion limitation than the conventional samples. 展开更多
关键词 zsm-5 zeolite MODIFICATION Methanol to olefins
下载PDF
Disproportionation of Toluene by Modified ZSM-5 Zeolite Catalysts with High Shape-selectivity Prepared Using Chemical Liquid Deposition with Tetraethyl Orthosilicate 被引量:15
12
作者 腾晖 王军 +1 位作者 任晓乾 陈德民 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2011年第2期292-298,共7页
Shape-selective catalysts for the disproportionation of toluene were prepared by the modification of the cylinder-shaped ZSM-5 zeolite extrudates with chemical liquid deposition with TEOS (tetraethyl orthosilicate).... Shape-selective catalysts for the disproportionation of toluene were prepared by the modification of the cylinder-shaped ZSM-5 zeolite extrudates with chemical liquid deposition with TEOS (tetraethyl orthosilicate).Various parameters for preparing catalysts were changed to investigate the suitable conditions.The resulting cata-lysts were tested in a pressured fixed bed reactor and characterized by SEM (scanning electron microscopy).The conversion of toluene and para-xylene selectivity were influenced remarkably by the n(SiO2)/n(Al2O3) ratio of ZSM-5 zeolite,the type and amount of deposition agent,acid and solvent used,and the time and cycle of deposition treatment.TEOS was proved to be a more efficient agent than the conventional polysiloxanes when the deposition amount was low.The catalyst prepared at the suitable conditions exhibited a high para-xylene selectivity of 91.1% with considerable high conversion of 25.6%.SEM analyses confirmed the formation of a layer of amorphous silica on the external surface of ZSM-5 zeolie crystals,which was responsible for the highly enhanced shape-selectivity. 展开更多
关键词 shape-selective catalysis zsm-5 zeolite disproportionation of toluene chemical liquid deposition tet-raethyl orthosilicate
下载PDF
Adsorption of Benzene and Propylene in Zeolite ZSM-5:Grand Canonical Monte Carlo Simulations 被引量:7
13
作者 SUN Xiao-yan LI Jian-wei +2 位作者 LI Ying-xia YAN Shi-cheng CHEN Biao-hua 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2009年第3期377-382,共6页
The adsorption behavior of benzene and propylene in zeolite ZSM-5 was studied by Grand Canonical Monte Carlo(GCMC) simulations. It could be found that benzene and propylene molecules showed different adsorption beha... The adsorption behavior of benzene and propylene in zeolite ZSM-5 was studied by Grand Canonical Monte Carlo(GCMC) simulations. It could be found that benzene and propylene molecules showed different adsorption behavior in the zeolite cavities. The loadings of propylene were significantly larger than those of benzene at 100 kPa. From the figures of potential energy distribution, the potential energy of benzene/zeolite was more negative than that of propylene/zeolite, so benzene could be adsorbed more stably than propylene. When the temperature was in- creased from 298 to 443 K at 100 kPa, the loading ofpropylene was reduced from 99 to 82 molecules, whereas that of benzene changed little. When benzene and propylene were adsorbed in zeolite simultaneously, the competitive adsorption of them occurred; therefore, the potential energy distribution could be changed significantly. Besides, the adsorption isotherms of benzene and propylene in ZSM-5 at 298 and 443 K were simulated. The results exhibit that the different factors influenced the molecular adsorption at various temperatures and pressures, leading to the diffe- rent rules for the adsorption of benzene and propylene molecules in the zeolite. At a low pressure, the unfavorable energy of propylene/zeolite and the "commensurate freezing" phenomenon of benzene would make the loadings of itself higher than those of propylene. When pressure was higher than 5 kPa, the adsorption of benzene in ZSM-5 would nearly reach saturation. 展开更多
关键词 zsm-5 zeolite ADSORPTION Grand canonical monte carlo
下载PDF
Core-shell-structured Composite ZSM-5@MCM-41 Catalysts:Fabrication,Characterization,and Enhanced Performance in Hexane Catalytic Cracking
14
作者 Zhu Jiale Zhu Xuedong Yang Fan 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS CSCD 2023年第4期41-51,共11页
A series of core-shell zeolites with a ZSM-5 zeolite core and a MCM-41 shell with varying shell thicknesses were successfully fabricated via a cetyltrimethylammonium bromide(CTAB)-directed sol-gel coating method in an... A series of core-shell zeolites with a ZSM-5 zeolite core and a MCM-41 shell with varying shell thicknesses were successfully fabricated via a cetyltrimethylammonium bromide(CTAB)-directed sol-gel coating method in an ultradilute solution. Extensive characterization techniques, including XRD, TEM, N_(2) adsorption-desorption, NH_(3)-TPD, and IR measurements, confirmed the successful coating of a microporous ZSM-5 core with a mesoporous MCM-41 shell layer and were further employed to explore the textural properties and acidic properties of the samples. The hexane cracking results revealed a significant enhancement in olefin yields after introducing the MCM-41 shell to ZSM-5. Interestingly, a volcanic trend in olefin yields was observed with the increase in the shell thickness. In particular, the highest olefin yield of 51.5%, exceeding that of the core catalyst by 17.1%, was achieved when the shell thickness was controlled at 40 nm.Moreover, the catalyst lifetime investigation revealed that the core-shell composite catalyst exhibited a minimal reduction in hexane conversion of merely 3.8% over a 120 h reaction period, significantly outperforming the 11.3% reduction exhibited by the core catalyst. This remarkable catalytic performance was attributed to the passivation of external acid sites and the introduction of more developed pore channels by the shell, which effectively mitigated unwanted side reactions. The successful synthesis of these core-shell structured catalysts presents a novel strategy for improving catalytic performance in hexane cracking, in addition to serving as a solid foundation for the design of industrial catalysts for light naphtha cracking. 展开更多
关键词 catalytic cracking light olefin CORE-SHELL zsm-5 zeolitE
下载PDF
Rapid synthesis of ZSM-5 zeolite catalyst for amination of ethanolamine 被引量:3
15
作者 华月明 胡望明 《Journal of Zhejiang University Science》 EI CSCD 2004年第6期705-708,共4页
ZSM-5 zeolite was rapidly synthesized in system containing ethylenediamine from the initial gel: (5?8) Na2O: 44 EDA:Al2O3:100 SiO2:4000 H2O. The crystals were lath-shaped. The effect of pretreatment and alkalinity on... ZSM-5 zeolite was rapidly synthesized in system containing ethylenediamine from the initial gel: (5?8) Na2O: 44 EDA:Al2O3:100 SiO2:4000 H2O. The crystals were lath-shaped. The effect of pretreatment and alkalinity on crystallinity was investigated. The pretreatment of silicate source can cut down the crystallization time. Tuning the system alkalinity and controlling crystallization time can ensure forming of pure crystal. 展开更多
关键词 zsm-5 zeolite SYNTHESIS PRETREATMENT ALKALINITY
下载PDF
Physicochemical Features of Phosphorus-Modified ZSM-5 Zeolite and Its Performance on Catalytic Pyrolysis to Produce Ethylene 被引量:3
16
作者 柯明 汪燮卿 张凤美 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2003年第6期671-676,共6页
The physicochemical features of phosphorus-modified ZSM-5 zeolites (SiO2/Al2O3 molar ratio is 25) were characterized by XRD(X-ray diffraction), BET(Brunauer, Emmett and Teller spcific surface area measurement), NH3-TP... The physicochemical features of phosphorus-modified ZSM-5 zeolites (SiO2/Al2O3 molar ratio is 25) were characterized by XRD(X-ray diffraction), BET(Brunauer, Emmett and Teller spcific surface area measurement), NH3-TPD(ammonia temperature-programmed desorption) and MASNMR(magic angle spinning nuclear magnetic resonance), and the performance on catalytic pyrolysis to produce ethylene was investigated with a light hydrocarbon fixed bed micro-reactor with n-octane as feed. The results show that the acid site density, acid intensity and hydrothermal stability of ZSM-5 zeolite were improved by phosphorus modification. When P2O5 content in ZSM-5 zeolite is higher than 2.5%, phosphorus modification can prevent ZSM-5 zeolite crystal structure transformation from orthorhombic to monoclinic. In addition, the dealumination of ZSM-5 zeolite framework was moderated by phosphorus modification under high temperature hydrothermal treatment. The results of n-octane pyrolysis on phosphorus-modified ZSM-5 zeolites show that ethylene yields of zeolites with different phosphorus content are almost the same under the same n-octane conversion. However, the modified zeolites with higher pyrolysis activity give lower yield of propene, butene and total olefin than lower pyrolysis activity under the same n-octane conversion. 展开更多
关键词 phosphorus-modified zsm-5 zeolite catalytic pyrolysis ETHYLENE hydrothermal stability magic angle spinning nuclear magnetic resonance
下载PDF
Effects of Metal Oxide in ZSM-5 Zeolite on Its Catalytic Performance in FCC Process 被引量:2
17
作者 Qin Jinlai Ouyang Ying +2 位作者 Li Minggang Luo Yibin Shu Xingtian(SINOPEC Research Institute of Petroleum Processing,Beijing 100083) 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2011年第2期43-46,共4页
Effects of metal oxide in ZSM-5 zeolite on its catalytic performance in fluid catalytic cracking reaction were studied via characterization by XRD and FT-IR spectroscopy using pyridine and collidine as molecular probe... Effects of metal oxide in ZSM-5 zeolite on its catalytic performance in fluid catalytic cracking reaction were studied via characterization by XRD and FT-IR spectroscopy using pyridine and collidine as molecular probes,and the modified ZSM-5 zeolite was evaluated in a micro reactor using standard light diesel fraction as the feedstock.Test results indicate that the metal species introduced into the ZSM-5 zeolite had led to the formation of Lewis acid centers.When the modified ZSM-5 zeolite with the metal species on its surface was used as the catalyst in FCC reaction,both the propylene yield and the propylene concentration in the liquefied petroleum gas increased,but in the meantime,more hydrogen and coke were formed at high conversion rate under the joint action of nonselective cracking of Lewis acid centers and dehydrogenation at metal centers on its outside surface. 展开更多
关键词 zsm-5 zeolite metal oxide fluid catalytic cracking PROPYLENE
下载PDF
Synthesis of ZSM-5 zeolite membranes without organic templates using a varying-concentration technique 被引量:1
18
作者 CHENG Yue LIAO Runhua LI Jiansheng Wang Lianjun Sun Xiuyun 《Rare Metals》 SCIE EI CAS CSCD 2006年第z1期384-389,共6页
Template-free nanosized ZSM-5 seeds with an average size of 15 nm were prepared from a synthesis solution with the composition 12Na2O∶100SiO2∶2Al2O3∶2500H2O. By the use of these seeds, thin ZSM-5 zeolite membranes ... Template-free nanosized ZSM-5 seeds with an average size of 15 nm were prepared from a synthesis solution with the composition 12Na2O∶100SiO2∶2Al2O3∶2500H2O. By the use of these seeds, thin ZSM-5 zeolite membranes were prepared on the outer surface of a porous α-alumina tube with a pore size of 2 μm in a gel system by varying-concentration synthesis with organic-free template. The first composition synthesis sol-gel was the same as seeds of molar composition and the second one was 12Na2O∶100SiO2∶2Al2O3∶5000H2O at 180 ℃ for 10 h, respectively. XRD shows that the film consists of well-crystallized ZSM-5 zeolite. SEM investigation indicats that the zeolite films on the supports are defect free and the film thickness is approximately 8 μm. The permeances for H2, N2, CH4 and CO2 are 8.94×10-7, 3.27×10-7, 3.9×10-7, 3.14×10-7 and 0.874×10-7 mol·m2·s-1·Pa-1, respectively. The ideal selectivity of membrane at room temperature for H2/CO2, H2/N2, H2/CH4 are 2.84, 2.73 and 2.29, respectively. 展开更多
关键词 TEMPLATE-FREE varying-concentration synthesis zsm-5 zeolite membrane PERMEANCE ideal selectivity
下载PDF
Hierarchically Structured Monolithic ZSM-5 through Macroporous Silica Gel Zeolitization 被引量:1
19
作者 Lei Qian Zhao Tianbo +2 位作者 Li Fengyan Zong Baoning Tong Yangchuan 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2006年第1期57-60,共4页
The hierarchically structured ZSM-5 monolith was prepared through transforming the skeletons of the macroporous silica gel into ZSM-5 by the steam-assisted conversion method. The morphology and monolithic shapes of ma... The hierarchically structured ZSM-5 monolith was prepared through transforming the skeletons of the macroporous silica gel into ZSM-5 by the steam-assisted conversion method. The morphology and monolithic shapes of macroporous silica gel were well preserved. The hierarchically structured ZSM-5 monolith exhibited the hierarchical porosity, with mesopores and macropores existing inside the macroporous silica gel, and micropores formed by the ZSM-5. The products have been characterized properly by using the XRD, SEM and N2 adsorption–desorption methods. 展开更多
关键词 zeolitE zsm-5 hierarchical porosity macroporous silica gel steam-assisted conversion
下载PDF
Synthesis and Characterization of ZSM-5/β Co-Crystalline Zeolite
20
作者 TianboZhao HuiyingZhang +2 位作者 FengyanLi ChaoYang BaoningZong 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2005年第2期95-100,共6页
ZSM-5/β co-crystalline zeolites with different content of ZSM-5 have beensynthesized by adding different amount of ZSM-5 to the synthetic system of β zeolite with NaAlO_2,silica sol as the source of aluminum and sil... ZSM-5/β co-crystalline zeolites with different content of ZSM-5 have beensynthesized by adding different amount of ZSM-5 to the synthetic system of β zeolite with NaAlO_2,silica sol as the source of aluminum and silica, respectively, and TEA^+ as the template undercontrolled condition of the synthesis. The ZSM-5/β co-crystalline zeolite was studied by XRD, SEM,BET and NH_3-TPD. The reaction activity of toluene alkylation was investigated with a mixture oftoluene-methanol as the feedstock in a pulse micro-reactor over the ZSM-5/β co-crystalline zeolite.It is found that ZSM-5/β co-crystalline zeolite has two kinds of zeolite structure including ZSM-5and β zeolite, not in the form of a physical mixture. The pore structure of ZSM-5/βco-crystalline zeolites is different from that for β zeolite, ZSM-5 and their physical mixture. Inaddition, the peaks of both high and low temperature desorption of ammonia over the ZSM-5/βco-crystalline zeolite shift 23℃ to lower temperatures and the acid amount of its strong acid is 3%more than the physical mixture. So the ZSM-5/β co-crystalline zeolite produces the highest contentof xylene, which is 10.4% higher than the physical mixture. And the ZSM-5/β co-crystalline zeolitehas better selectivity for toluene alkylation and weaker de-methylation than β zeolite, ZSM-5 andtheir physical mixture. 展开更多
关键词 β zeolite zsm-5 co-crystalline zeolitE SYNTHESIS CHARACTERIZATION
下载PDF
上一页 1 2 4 下一页 到第
使用帮助 返回顶部