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Study of the Conversion of Postconsumer Polystyrene on CeO2/HZSM-5 Type Materials
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作者 Mirna Oliveira Sant’Ana Anne Michelle Garrido Pedrosa Marcelo José Barros de Souza 《Journal of Materials Science and Chemical Engineering》 2024年第4期29-41,共13页
The catalytic conversion of polystyrene (PS) was studied in the presence of the materials type HZSM-5, CeO<sub>2</sub>, 10% CeO<sub>2</sub>/HZSM-5 and 20% CeO<sub>2</sub>/HZSM-5, wh... The catalytic conversion of polystyrene (PS) was studied in the presence of the materials type HZSM-5, CeO<sub>2</sub>, 10% CeO<sub>2</sub>/HZSM-5 and 20% CeO<sub>2</sub>/HZSM-5, which were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and nitrogen adsorption at 77K. The catalytic tests were performed via thermogravimetric analysis (TG) at heating rates of 5, 10 and 20˚C min<sup>−1</sup> in a temperature range from 30˚C to 900˚C. For the tests, a ratio of 30% by mass of each catalytic material mixed with PS was used and the activation energy of the degradation process was determined by the Vyazovkin method. The obtained results showed that the addition of the catalyst to the PS in general reduced its degradation temperature. The 10% CeO<sub>2</sub>/HZSM-5 catalyst showed greater efficiency, as it resulted in lower activation energy for PS degradation. Thus, the combination of CeO<sub>2</sub> with HZSM-5 resulted in materials with potential for application in the catalytic degradation of polystyrene and the results indicate that the production of a composite material can be a good strategy to generate an increase in catalytic activity and a decrease in energy process activation. 展开更多
关键词 hzsm-5 zeolite Cerium Oxide POLYSTYRENE PYROLYSIS
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Effects of Light Rare Earth on Acidity and Catalytic Performance of HZSM-5 Zeolite for Catalytic Cracking of Butane to Light Olefins 被引量:31
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作者 王晓宁 赵震 +3 位作者 徐春明 段爱军 张莉 姜桂元 《Journal of Rare Earths》 SCIE EI CAS CSCD 2007年第3期321-328,共8页
The effects of rare earth(RE)on the structure,acidity,and catalytic performance of HZSM-5 zeolite were investigated.A series of RE/HZSM-5 catalysts,containing 7.54% RE(RE=La,Ce,Pr,Nd,Sm,Eu or Gd),were prepared by ... The effects of rare earth(RE)on the structure,acidity,and catalytic performance of HZSM-5 zeolite were investigated.A series of RE/HZSM-5 catalysts,containing 7.54% RE(RE=La,Ce,Pr,Nd,Sm,Eu or Gd),were prepared by the impregnation of the ZSM-5 type zeolites(Si/Al=64:1)with the corresponding RE nitrate aqueous solutions.The catalysts were characterized by means of FT-IR,UV-Vis,NH3-TPD,and IR spectroscopy of adsorbed pyridine.The catalytic performances of the RE/HZSM-5 for the catalytic cracking of mixed butane to light olefins were also measured with a fixed bed microreactor.The results revealed that the addition of light rare earth metal on the HZSM-5 catalyst greatly enhanced the selectivity to olefins,especially to propylene,thus increasing the total yield of olefins in the catalytic cracking of butane.Among the RE-modified HZSM-5 samples,Ce/HZSM-5 gave the highest yield of total olefins,and Nd/HZSM-5 gave the highest yield of propene at a reaction temperature of 600℃.The presence of rare earth metal on the HZSM-5 sample,not only modified the acidic properties of HZSM-5 including the amount of acid sites and acid type,that is,the ratio of L/B(Lewis acid/Brnsted acid),but also altered the basic properties of it,which in turn promoted the catalytic performance of HZSM-5 for the catalytic cracking of butane. 展开更多
关键词 fight rare earth hzsm-5 zeolite catalytic cracking BUTANE ACIDITY
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Effects of Calcination Temperature on the Acidity and Catalytic Performances of HZSM-5 Zeolite Catalysts for the Catalytic Cracking of n-Butane 被引量:4
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作者 Jiangyin Lu Zhen Zhao Chunming Xu Aijun Duan Pu Zhang 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2005年第4期213-220,共8页
The acidic modulations of a series of HZSM-5 catalysts were successfully made by calcination at different treatment temperatures, i.e. 500, 600, 650, 700 and 800 ℃, respectively. The results indicated that the total ... The acidic modulations of a series of HZSM-5 catalysts were successfully made by calcination at different treatment temperatures, i.e. 500, 600, 650, 700 and 800 ℃, respectively. The results indicated that the total acid amounts, their density and the amount of B-type acid of HZSM-5 catalysts rapidly decreased, while the amounts of L-type acid had almost no change and thus the ratio of L/B was obviously enhanced with the increase of calcination temperature (excluding 800 ℃). The catalytic performances of modified HZSM-5 catalysts for the cracking of n-butane were also investigated. The main properties of these catalysts were characterized by means of XRD, N2 adsorption at low temperature, NH3-TPD, FTIR of pyridine adsorption and BET surface area measurements. The results showed that HZSM-5 zeolite pretreated at 800 ℃ had very low catalytic activity for n-butane cracking. In the calcination temperature range of 500-700 ℃, the total selectivity to olefins, propylene and butene were increased with the increase of calcination temperature, while, the selectivity for arene decreased with the calcination temperature. The HZSM-5 zeolite calcined at 700 ℃ produced light olefins with high yield, at the reaction temperature of 650 ℃ the yields of total olefins and ethylene were 52.8% and 29.4%, respectively. Besides, the more important role is that high calcination temperature treatment improved the duration stability of HZSM-5 zeolites. The effect of calcination temperature on the physico-chemical properties and catalytic performance of HZSM-5 for cracking of n-butane was explored. It was found that the calcination temperature had large effects on the surface area, crystallinity and acid properties of HZSM-5 catalyst, which further affected the catalytic performance for n-butane cracking. 展开更多
关键词 hzsm-5 zeolite catalyst acidic modification calcination temperature N-BUTANE catalytic cracking OLEFIN
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Influence of the post-treatment of HZSM-5 zeolite on catalytic performance for alkylation of benzene with methanol 被引量:17
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作者 Qingtao Wang Wenwen Han +5 位作者 Hualei Hu Jinghui Lyu Xiaolong Xu Qunfeng Zhang Hongjing Wang Xiaonian Li 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2017年第12期1777-1783,共7页
The porous material HZSM-5 zeolite with micro-mesopore hierarchical porosity was prepared by post-treatment (combined alkali treatment and acid leaching) of parent zeolite and its catalytic performance for benzene a... The porous material HZSM-5 zeolite with micro-mesopore hierarchical porosity was prepared by post-treatment (combined alkali treatment and acid leaching) of parent zeolite and its catalytic performance for benzene alkylation with methanol was investigated. The effect of post-treatment on the textural properties was characterized by various techniques (including ICP-AES, XRD, nitrogen sorption isotherms, SEM, NH3-TPD, Py-IR and TG). The results indicated that the post-treatment could modify the structural and acidic properties of HZSM-5 zeolite. In this procedure, not only additional mesopores were created by selective extraction of silicon but also the acidity was tuned. Consequently, the modified HZSM-5 zeolite showed larger external surface area with less acid sites as compared to the parent zeolite. It was found out that the modified zeolite exhibited a higher benzene conversion and xylene selectivity for alkylation of benzene with methanol as well as excellent life span of the catalyst than conventional ones. This can be explained by the facts that the presence of additional mesopores improved the diffusion property in the reactions. Furthermore, the modified zeolite showed an appropriate Bronsted acidity for effective suppression of the side reaction of methanol to olefins, thus reduced the accumulation of coke on the HZSM-5 zeolite, which was favorable for the catalyst stability. In comparison with the parent HZSM-5 zeolite, the modified zeolite by alkali treatment and acid leaching showed better performance for the benzene alkylation with methanol. 展开更多
关键词 hzsm-5 zeolite Hierarchical porosity Post-treatment Benzene alkylation with methanol
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Influence of the Alkali Treatment of HZSM-5 Zeolite on Catalytic Performance of PtSn-Based Catalyst for Propane Dehydrogenation 被引量:2
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作者 Huang Li Zhou Shijian +3 位作者 Zhou Yuming Zhang Yiwei Xu Jun Wang Li 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2013年第2期11-18,共8页
The porous material ATZ with micro-mesopore hierarchical porosity was prepared by alkali treatment of parent HZSM-5 zeolite and applied for propane dehydrogenation. The zeolite samples were characterized by XRD, N2- p... The porous material ATZ with micro-mesopore hierarchical porosity was prepared by alkali treatment of parent HZSM-5 zeolite and applied for propane dehydrogenation. The zeolite samples were characterized by XRD, N2- physisorption, and NH3-TPD analysis. The results showed that the alkali treatment can modify the physicochemical prop- erties of HZSM-5 zeolite. In this case, the porous material ATZ showed larger extemal surface area with less acid sites as compared to the HZSM-5 zeolite. It was found out that the alkali treatment of HZSM-5 zeolite could promote the catalytic performance of PtSn/ATZ catalyst. The possible reason was ascribed to the low acidity of ATZ. Furthermore, the presence of mesopores could reduce the carbon deposits on the metallic surface, which was also favorable for the dehydrogenation reaction. 展开更多
关键词 hzsm-5 zeolite alkali-treatment propane dehydrogenation PROPENE
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Properties and Characterization of Modified HZSM-5 Zeolites 被引量:1
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作者 RenqingLu HejinTangbo +1 位作者 QiuyingWang ShouheXiang 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2003年第1期56-62,共7页
Physicochemical and catalytic properties of phosphorus and boron modified HZSM-5 zeolites treated with 100% steam at 673 K were investigated. The acidity and distribution of acidic sites were studied by infrared spect... Physicochemical and catalytic properties of phosphorus and boron modified HZSM-5 zeolites treated with 100% steam at 673 K were investigated. The acidity and distribution of acidic sites were studied by infrared spectroscopy using pyridine as probe molecule and temperature programmed desorption (TPD) of ammonia. The structure of the samples was characterized by XRD, and the textural properties of the catalysts were determined by nitrogen isothermal adsorption-desorption measurements and scanning electron microscopy (SEM). The XRD results show that the modified samples have no novel crystalline phase, indicating a high dispersion of phosphorus and boron species. After treatment, the microporous volume and surface area of the samples markedly decrease, implying the blockage of the channel. The nitrogen adsorption-desorption measurements suggest that the isothermal type of all samples is a combination of isothermal type I and IV, and all hysteresis loops resemble the H4-type in the IUPAC classification. The total acidity of the modified samples, determined by pyridine adsorption IR and TPD of ammonia, decreases in contrast to that of the parent HZSM-5. The conversion of n-heptane over P and B steam-modified HZSM-5 is higher than that of P and B-modified HZSM-5 zeolites but lower than that of the parent HZSM-5. 展开更多
关键词 hzsm-5 zeolite steam treatment PHOSPHORUS BORON secondary pore TEXTURE cracking activity
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Effects of Operating Conditions on the Catalytic Performance of HZSM-5 Zeolites in n-Pentane Cracking 被引量:1
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作者 Hou Xu Zhao Liu +3 位作者 Ma Zhenzhou Chen Bochong Feng Jingyuan Cui Tingting 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2021年第1期67-75,共9页
In this work,n-pentane catalytic cracking over HZSM-5 zeolites was studied at 650°C under atmosphere pressure.A particular attention was paid to the measurement of n-pentane conversion,light olefins production,pr... In this work,n-pentane catalytic cracking over HZSM-5 zeolites was studied at 650°C under atmosphere pressure.A particular attention was paid to the measurement of n-pentane conversion,light olefins production,product distribution,coke deposit,etc.Several indexes were defined to evaluate the effects of operating conditions on the catalytic performance of HZSM-5 zeolites.It was found that decreasing the weight hourly space velocity,increasing the reactant partial pressure,and increasing the carrier gas flow rate could inhibit C-H bond breaking and enhance the C-C bond breaking and hydride transfer reactions,leading to reduced alkenes selectivity,which suppressed the formation of external coke and alleviated the deactivation of HZSM-5 zeolites.It was deduced that the catalytic stability of HZSM-5 zeolites was improved at the cost of alkenes selectivity.Compared with decreasing the weight hourly space velocity and increasing the reactant partial pressure,increasing the carrier gas flow rate could enhance the diffusion process and protect alkenes from being consumed in coke formation in order to improve the catalytic stability of HZSM-5 zeolites with less reduction of alkenes selectivity. 展开更多
关键词 operating conditions hzsm-5 zeolites catalytic performance n-pentane cracking light olefins
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Investigation of the Surface State of Zeolite HZSM-5 Pretreated with Toluene by Using Fast Atom Bombardment Mass Spectrometry (FABMS)
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作者 Zhu, JH Xu, QH 《Chinese Chemical Letters》 SCIE CAS CSCD 1998年第7期671-674,共4页
Toluene pretreatment caused many activated toluene species existing on the surface of zeolite HZSM-5, by which the activity of sample was increased. Moreover, variation in the surface Si+/Al+ ratio of HZSM-5 was sensi... Toluene pretreatment caused many activated toluene species existing on the surface of zeolite HZSM-5, by which the activity of sample was increased. Moreover, variation in the surface Si+/Al+ ratio of HZSM-5 was sensitively detected by FABMS. 展开更多
关键词 zeolite hzsm-5 surface state FABMS toluene ethylation
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氧化镁改性对纳米HZSM-5分子筛催化甲醇制丙烯的影响 被引量:15
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作者 毛东森 郭强胜 孟涛 《物理化学学报》 SCIE CAS CSCD 北大核心 2010年第8期2242-2248,共7页
采用浸渍法制备了一系列不同Mg含量(0-8%,w)的改性纳米HZSM-5分子筛.利用X射线衍射(XRD)、铝固体魔角旋转核磁共振(27AlMASNMR)、N2吸附/脱附、氨-程序升温脱附(NH3-TPD)和吡啶吸附傅里叶变换红外(FT-IR)光谱等技术对改性前后样品的结... 采用浸渍法制备了一系列不同Mg含量(0-8%,w)的改性纳米HZSM-5分子筛.利用X射线衍射(XRD)、铝固体魔角旋转核磁共振(27AlMASNMR)、N2吸附/脱附、氨-程序升温脱附(NH3-TPD)和吡啶吸附傅里叶变换红外(FT-IR)光谱等技术对改性前后样品的结构和酸性进行了详细表征;并在常压、500℃和甲醇空速(WHSV)为1.0h-1的反应条件下,在连续流动固定床反应器上考察了其对甲醇制丙烯反应的催化性能.结果表明,随着Mg含量的增加,丙烯和丁烯的选择性逐渐增大,而甲烷、乙烯和芳烃的选择性逐渐降低.催化剂的稳定性先随Mg含量的增加而增加,当Mg含量为2%时达到最大,之后又随Mg含量的增加而降低.MgO改性对纳米HZSM-5分子筛催化性能的影响主要是由其酸性和织构性能的改变而引起的. 展开更多
关键词 甲醇 丙烯 纳米hzsm-5分子筛 氧化镁改性 选择性 稳定性
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纳米HZSM-5催化剂催化烃类转化反应 被引量:5
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作者 张培青 郭洪臣 +3 位作者 祝洪杰 王祥生 姜雪梅 王萍 《高等学校化学学报》 SCIE EI CAS CSCD 北大核心 2006年第12期2366-2371,共6页
制备了纳米(20~50nm)HZSM-5催化剂,用XRF,TEM和NH3-TPD等手段对催化剂进行了表征.以正辛烷及苯和正辛烷混合物的转化为模型反应,研究了单烃和混合烃在纳米HZSM-5催化剂上的转化行为,考察了反应条件对产物分布的影响.结果表明... 制备了纳米(20~50nm)HZSM-5催化剂,用XRF,TEM和NH3-TPD等手段对催化剂进行了表征.以正辛烷及苯和正辛烷混合物的转化为模型反应,研究了单烃和混合烃在纳米HZSM-5催化剂上的转化行为,考察了反应条件对产物分布的影响.结果表明,纳米HZSM-5沸石催化剂具有很强的烃类转化能力,烃类通过芳构化、异构化和烷基化等反应转化为高辛烷值的异构烷烃和芳烃,产物中异构烷烃(C4-C6)和芳烃的质量分数超过90%.直链烷烃转化为芳烃以生成苯环为主,混合烃转化为芳烃以苯和小分子烃的烷基化为主.控制反应条件町抑制苯和cf芳烃的生成.产物分析结果表明,烃类在纳米HZSM-5催化剂上的裂解、芳构化和异构化等遵循正碳离子机理. 展开更多
关键词 纳米hzsm-5沸石 正辛烷 异构化 芳构化 烷基化
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水热处理和硅烷化对ZnO/HZSM-5催化直馏汽油芳构化性能的影响 被引量:8
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作者 蔡博 龙化云 +1 位作者 靳凤英 郭新闻 《石油炼制与化工》 CAS CSCD 北大核心 2012年第12期23-28,共6页
对纳米HZSM-5分子筛进行水热处理并采用正硅酸乙酯对其改性后制备Si/HZSM-5催化剂,在此基础上采用硝酸锌等体积浸渍法改性制备Si-ZnO/HZSM-5催化剂。以直馏汽油为原料,考察水热处理温度以及硅烷化程度对ZnO/HZSM-5催化剂芳构化性能的影... 对纳米HZSM-5分子筛进行水热处理并采用正硅酸乙酯对其改性后制备Si/HZSM-5催化剂,在此基础上采用硝酸锌等体积浸渍法改性制备Si-ZnO/HZSM-5催化剂。以直馏汽油为原料,考察水热处理温度以及硅烷化程度对ZnO/HZSM-5催化剂芳构化性能的影响。结果表明:随着水热处理温度的升高,芳构化稳定性先增加后降低,说明适宜的水热处理温度有利于催化剂在直馏汽油芳构化中保持良好的活性和稳定性。硅烷化可进一步改善催化剂的芳构化稳定性,降低催化剂积炭量,但当SiO2质量分数超过12%后,由于催化剂孔口缩小,导致催化剂芳构化性能明显下降。 展开更多
关键词 直馏汽油 芳构化 纳米ZSM-5分子筛 水热处理 硅烷化
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Methane dehydro-aromatization over Mo/HZSM-5 catalysts in the absence of oxygen:Effect of steam-treatment on catalyst stability 被引量:2
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作者 Tingting Zhao Hongxia Wang 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2011年第5期547-552,共6页
The effect of steam-treatment to HZSM-5 zeolite and Mo/HZSM-5 with a steaming time range of 0.5-1 h on the catalytic performance of methane dehydro-aromatization (MDA) over Mo/HZSM-5 catalyst prepared with impregnat... The effect of steam-treatment to HZSM-5 zeolite and Mo/HZSM-5 with a steaming time range of 0.5-1 h on the catalytic performance of methane dehydro-aromatization (MDA) over Mo/HZSM-5 catalyst prepared with impregnation has been studied in detail in combination with the characterization of 1H MAS NMR technique. Both the deactivation rate constant (kd) and the Brtnsted acid sites per unit cell were calculated to quantitatively evaluate the stability of Mo/HZSM-5 catalysts treated with steam at 813 K before and after impregnation of molybdenum species, and the corresponding variation of their Brtnsted acid sites. The results reveal that a V-shape relationship between kd and the number of B 1 acid sites per unit cell is presented on Mo/HZSM-5 catalyst under the tested steam-treatment and reaction conditions. 展开更多
关键词 steam-treatment hzsm-5 zeolite MO/hzsm-5 methane dehydro-aromatization in the absence of oxygen
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Studies on Mo/HZSM-5 Complex Catalyst for Methane Aromatization 被引量:1
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作者 Qun Dong Xiaofei Zhao +1 位作者 Jian Wang M.Ichikawa 《Journal of Natural Gas Chemistry》 CAS CSCD 2004年第1期36-40,共5页
The influence of adding Fe, Cr, Co, and Ga into 3%Mo/HZSM-5 catalyst on methane aromatization, and the influence of additives ratio on methane conversion, selectivity to hydrocarbons and coke, as well as distribution ... The influence of adding Fe, Cr, Co, and Ga into 3%Mo/HZSM-5 catalyst on methane aromatization, and the influence of additives ratio on methane conversion, selectivity to hydrocarbons and coke, as well as distribution of aromatics were investigated. The experimental results showed that the addition of Fe, Cr, Co and Ga promoted the dehydrogenation and dissociation of methane. The results of NH3-TPD indicated that the acidity of HZSM-5 was changed by adding Fe and Co components, consequently the catalytic properties of Mo/HZSM-5 were changed. It was also revealed that strong acid sites were the center of methane aromatization. The results of XRD characterization showed that the crystallinity of Mo on ZSM-5 zeolite was increased after adding Fe, Co additives. 展开更多
关键词 METHANE AROMATIZATION BENZENE hzsm-5 zeolite Fe GA CR Co
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Catalytic activity of phosphorus and steam modified HZSM-5 and the theoretical selection of phosphorus grafting model 被引量:1
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作者 Renqing Lu Zuogang Cao Xinhai Liu 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2008年第2期142-148,共7页
The modification of HZSM-5 zeolite with phosphorus and steam has been studied. Results show that 1% phosphorus and steam modified HZSM-5 has the highest catalytic activity for n-heptane. Physicochemical and catalytic ... The modification of HZSM-5 zeolite with phosphorus and steam has been studied. Results show that 1% phosphorus and steam modified HZSM-5 has the highest catalytic activity for n-heptane. Physicochemical and catalytic properties of 1% phosphorus and steam modified HZSM-5 zeolites have been investigated. The X-ray diffraction (XRD) results exhibit that there is considerable variation in the relative intensity of the individual diffraction peaks. The acidity of the samples decreases with an increase in the steaming temperature, which is determined by the IR of adsorbed pyridine and temperature programmed desorption (TPD) of ammonia. The oxidation state of phosphorus shown by XPS is +5, and a model for surface structure modification is proposed. The nitrogen adsorption isotherm for all samples is a combination of type I and type IV, all hysteresis loops resemble the H4-type. The density functional and cluster model methods have been invoked to select the phosphorus grafting model, and it was found that the phosphorus grafting model were more probable in the form of the terminal oxygen coordinating with aluminum. 展开更多
关键词 hzsm-5 zeolites steam treatment phosphorous acid modification cracking activity cluster model
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Catalytic cracking of 1-butene to propylene by Ag modified HZSM-5 被引量:3
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作者 张荣荣 王正宝 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第7期1131-1137,共7页
Silver modified HZSM-5 (AgHZ) zeolite catalysts were prepared by ion exchange method and their catalytic properties in the l-butene cracking reaction were measured. The catalysts were characterized by infrared spec-... Silver modified HZSM-5 (AgHZ) zeolite catalysts were prepared by ion exchange method and their catalytic properties in the l-butene cracking reaction were measured. The catalysts were characterized by infrared spec- troscopy with pyridine adsorption (Py-IR), N2 adsorption and X-ray diffraction (XRD). The effects of Ag loading and steaming treatment on catalytic performances were studied. It is found that the activity ofHT_SM-5 (HZ) catalyst significantly decreases with the steaming time, whereas AgHZ catalysts show stable activity in the steaming time of 24-48 h and their activities increase with the Ag loading. When the steaming time is 24-48 h, the yield of propylene over HZ catalyst significantly decreases, whereas it is stable over AgHZ catalysts. The AgHZ catalysts with Ag loadings of 0.28%-0.43% (by mass) show similar propylene yields (-30%), which are higher than that over the AgHZ catalyst with a Ag loading of 0.55% (by mass). These results indicate that the steam-treated AgHZ catalysts with optimum Ag loadings have higher yield of propylene and are more stable than the steam- treated HZ catalyst. The regeneration stability measurement in butene cracking also shows that the AgHZ catalyst steam-treated under a suitable condition has better stability than the HZ catalyst. 展开更多
关键词 1-8utene Propylene Cracking hzsm-5 zeolite Silver
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FINE CONTROL OF HZSM-5'S PORE-OPENING SIZE BY A NEW CVD METHOD
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作者 董飞 王桂茹 王祥生 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 1995年第4期25-31,共7页
A new CVD method without vacuum condition(CVDWV)was designed in this study,ithad been found that by modifying the flow rate of the carrier gas(N<sub>2</sub>)and the temperature of sur-face reaction,sil... A new CVD method without vacuum condition(CVDWV)was designed in this study,ithad been found that by modifying the flow rate of the carrier gas(N<sub>2</sub>)and the temperature of sur-face reaction,silicon saturator and sample tube,the amount of silica deposited on the external sur-face of the zeolite could be precisely controlled,The changes in the physicochemical properties ofzeolite,such as pore-opening size,acidity and reaction property were investigated.The results ob-tained showed that:modification of the improved CVD method did not change the internal structureand acidity of the zeolite,but could bring about significant change of pore-opening size and reactionproperty as desired. 展开更多
关键词 hzsm-5 CVD zeolite pore-opening SIZE silica adsorption external surface DEPOSIT
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Catalyst activity comparison of alcohols over zeolites
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作者 Karthikeyan K. Ramasamy Yong Wang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2013年第1期65-71,共7页
Alcohol transformation to transportation fuel-range hydrocarbon over HZSM-5 (SIO2/A1203 = 30) catalyst was studied at 360 C and 300 psig. Product distributions and catalyst life were compared between methanol, ethan... Alcohol transformation to transportation fuel-range hydrocarbon over HZSM-5 (SIO2/A1203 = 30) catalyst was studied at 360 C and 300 psig. Product distributions and catalyst life were compared between methanol, ethanol, 1-propanol and 1-butanol as a feed. The catalyst life for 1-propanol and l-butanol was more than double compared with that for methanol and ethanol. For all the alcohols studied, the product distributions (classified to paraffin, olefin, naphthene, aromatic and naphthalene compounds) varied with time on stream (TOS). At 24 h TOS, liquid product from 1-propanol and 1-butanol transformation primarily contains higher olefin compounds. The alcohol transformation process to higher hydrocarbon involves a complex set of reaction pathways such as dehydration, oligomerization, dehydrocyclization and hydrogenation. Compared with ethylene generated from methanol and ethanol, oligomerization of propylene and butylene has a lower activation energy and can readily take place on weaker acidic sites. On the other hand, dehydrocyclization of the oligomerized products of propylene and butylene to form the cyclic compounds requires the sites with stronger acid strength. Combination of the above mentioned reasons are the primary reasons for olefin rich product generated in the later stage of the time on stream and for the extended catalyst life time for 1-propanol and 1-butanol compared with methanol and ethanol conversion over HZSM-5. 展开更多
关键词 zeolite hzsm-5 alcohol conversion catalyst activity hydrocarbons
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Study on Synthesis and Catalytic Performance of Hierarchical Zeolite
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作者 Zhang Lingling Li Fengyan +1 位作者 ZhaoTianbo Sun Guida 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2007年第3期57-60,共4页
A kind of hierarchical zeolite catalyst was synthesized by hydrothermal method. X-ray diffraction (XRD) and nitrogen adsorption-desorption method were used to study the phase and aperture structure o( the prepared ... A kind of hierarchical zeolite catalyst was synthesized by hydrothermal method. X-ray diffraction (XRD) and nitrogen adsorption-desorption method were used to study the phase and aperture structure o( the prepared catalyst. Infrared (IR) spectra of pyridine adsorbed on the sample showed that the hierarchical zeolite really had much more Bronsted and Lewis acidic sites than the HZSM-5 zeolite. The catalytic cracking of large hydrocarbon molecules showed that the hierarchical zeolite had a higher catalytic activity than the HZSM-5 zeolite. 展开更多
关键词 hierarchical zeolite catalytic cracking of large hydrocarbon molecules SELECTIVITY hzsm-5zeolite
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纳米ZSM-5沸石对芳烃苄基化反应的催化性能 被引量:11
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作者 苗海霞 薛招腾 +2 位作者 马静红 张元春 李瑞丰 《催化学报》 SCIE EI CAS CSCD 北大核心 2012年第1期183-191,共9页
采用晶种有机硅烷化法合成了纳米团簇 ZSM-5 沸石, 考察了其在芳烃苄基化反应中的催化活性. X 射线衍射、N2 吸附和扫描电镜等结果表明, 该沸石为由约 20 nm 的小晶粒聚集成的团簇体, 并形成晶间中孔, 其具有的外表面积是普通 ZSM-5 沸... 采用晶种有机硅烷化法合成了纳米团簇 ZSM-5 沸石, 考察了其在芳烃苄基化反应中的催化活性. X 射线衍射、N2 吸附和扫描电镜等结果表明, 该沸石为由约 20 nm 的小晶粒聚集成的团簇体, 并形成晶间中孔, 其具有的外表面积是普通 ZSM-5 沸石的 5 倍之多. NH3-程序升温脱附和吡啶吸附的红外光谱结果显示, 沸石的纳米化可使其表面酸中心, 尤其是强酸中心的数目增多, 大大提高了大分子的酸性位可接近性. 在芳烃苄基化反应中, 纳米 ZSM-5 沸石克服了反应分子空间位阻对催化活性的影响, 表现出优异的催化活性, 363 K 时, 甲苯苄基化反应的速率常数是普通 ZSM-5 沸石的约 13 倍. 展开更多
关键词 纳米 ZSM-5 沸石 有机硅烷化 芳烃苄基化 酸性 可接近性
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硅烷化处理的纳米ZSM-5的结构表征及催化性能 被引量:10
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作者 王坤院 王祥生 +1 位作者 李钢 龙化云 《催化学报》 SCIE CAS CSCD 北大核心 2007年第7期617-621,共5页
采用多次浸渍法和化学反应沉积法对纳米HZSM-5分子筛外表面进行了硅烷化处理,考察了改性后纳米ZSM-5对甲苯歧化的催化活性.采用改进的Hammett指示剂法和吡啶吸附红外光谱研究了催化剂的酸性位,采用X射线衍射和29Si MASNMR对催化剂的结... 采用多次浸渍法和化学反应沉积法对纳米HZSM-5分子筛外表面进行了硅烷化处理,考察了改性后纳米ZSM-5对甲苯歧化的催化活性.采用改进的Hammett指示剂法和吡啶吸附红外光谱研究了催化剂的酸性位,采用X射线衍射和29Si MASNMR对催化剂的结构进行了表征.研究结果表明,硅烷化处理降低了纳米ZSM-5酸性位的浓度,从而降低了纳米ZSM-5的催化活性.硅烷化处理还减少了纳米ZSM-5中Si的Q4物种,降低了纳米ZSM-5的相对结晶度,同时硅烷化处理产生了脱铝作用.骨架铝含量的减少导致催化剂的酸性位减少,催化活性降低. 展开更多
关键词 纳米ZSM-5沸石 硅烷化 甲苯 歧化
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