On the conversion of 1‐butene over Pt‐ZSM5

The conversion of 1‐butene over Pt‐ZSM5 was studied in the presence and absence of hydrogen. In the absence of hydrogen, the catalytic activity of the metal was rapidly poisoned and in the steady state the catalyst showed identical properties as the parent ZSM5. In the presence of hydrogen, the skeletal isomerization of butene was not affected, but the rate of oligomerization/cracking was enhanced. From the by‐products butadiene, propane, ethane and methane, ethane and propane originated mainly from oligomerization/cracking on the acid sites and not from hydrogenolysis on Pt. The contribution of the metal to the overall by‐product formation was small. Thus, an adaptation of the acid rather than of the metal sites is necessary to improve the performance of the bifunctional catalyst. This revised version was published online in July 2006 with corrections to the Cover Date.     

ZSM-5沸石晶粒尺寸对合成膜性能的影响

利用水热法,于１７０℃下在多孔α－Ａｌ２Ｏ３载体管上一次水热晶化合成了晶粒大小分别为７～８μｍ和２～３μｍ的ＺＳＭ－５沸石膜,并分别利用ＸＲＤ、ＳＥＭ和单组分气体渗透作了表征。结果表明,该膜确为完整致密无缺陷的沸石膜。由２～３μｍ晶粒形成的膜比７～８μｍ晶粒形成的膜薄,且气体渗透率高,但理想选择因数低,说明相对小的晶粒并不能形成高质量的膜。在成膜过程中,晶粒与载体之间有一匹配效应。     

吸附分离二乙苯异构体的吸附剂的制备与色谱评价

用直接法合成的ＺＳＭ－５分子筛作吸附分离二乙苯异构体的吸附剂。在１００％水蒸气氛围中，７００°Ｃ高温下焙烧８ｈ的ＺＳＭ－５分子筛对二乙苯异构体有较高的分离能力，在工业上有一定的应用前景。     

催化裂解制丙烯新型催化剂的研究

以催化重整石脑油为原料,水热处理磷改性HZSM-5分子筛为催化剂,考察了改性催化剂的催化裂解性能。结果表明,催化剂最佳改性条件为:水热处理温度700℃,处理时间1 h,处理空速2 h-1。最佳反应条件为:温度650℃,液体空速4 h-1,水/原料油(体积比)0.75,压力0.2 MPa。在此条件下,与未改性HZSM-5分子筛催化剂相比,改性者水热稳定性增强,丙烯收率提高;在磷负载质量分数为3%时,丙烯收率最高,达到22.62%。     

小晶粒ZSM-5的表征、磷改性及其在多产丙烯FCC催化剂中的应用

ZSM 5是催化裂化催化剂中的重要组分,对于增加丙烯产率有显著作用。采用XRD、SEM和粒度分析(SDP) 表征了常规(大晶粒)和小晶粒2种ZSM 5分子筛。对这2种ZSM 5分子筛进行磷改性,并对它们进行水洗实验,考察改性元素流失情况。以上述2种磷改性ZSM 5分子筛制备FCC催化剂,采用磨损指数、固定流化床装置(FFB)等方法评价催化剂催化性能。结果表明,小晶粒ZSM 5分子筛与常规ZSM 5分子筛相比,相对结晶度高,平均粒度显著小,颗粒分散均匀,条状物少。对小晶粒ZSM 5分子筛进行磷改性,可以减少改性元素的流失,进而大幅提高催化剂活性稳定性;磷改性小晶粒ZSM 5分子筛在800℃下水热处理17 h,结晶度保留率达到976%。采用磷改性小晶粒ZSM 5分子筛制备FCC催化剂,可以大大降低催化剂的磨损指数,同时增加对丙烯的选择性,提高丙烯产率。工业应用表明,丙烯产率可以提高074百分点。     

ZSM35分子筛催化剂上1-己烯骨架异构化反应的研究

在H2/1-己烯=8(分子比),p=0.2MPa,T=270℃,SV=1.0h-1的条件下比较了Si-ZSM12、Si-ZSM35、Si-Y、Si-SAPO114种分子筛催化剂的1-己烯骨架异构化反应性能,结果表明:弱酸中心可以满足1-己烯的骨架异构化催化过程;具有0.4～0.6nm孔径的分子筛是1-己烯进行骨架异构的前提条件,研究表明,对于1-己烯骨架异构化反应,在反应温度270℃,反应压力0.2～1.0MPa的反应条件下,Si-ZSM35分子筛催化剂具有独特的1-己烯骨架异构化性能。     

The versatile synthesis method for hierarchical micro‐ and mesoporous zeolite: An embedded nanocarbon cluster approach

In this work, we are reporting for the first time the synthesis of hierarchical micro‐ and mesoporous zeolite using silica–carbon (SiO₂/C) composites prepared by pyrolysis of carbonaceous gases in the presence of silica gel. The pyrolysis effectively yielded carbon deposited onto the raw silica material. The obtained SiO₂/C composites were utilised as a bifunctional material, mesoporous template and silica source, for the zeolite synthesis. Tetrapropylammonium hydroxide (TPAOH) was used as a microporous template. The combination of the obtained composites and the TPAOH for the hydrothermal synthesis resulted in the formation of hierarchical micro‐ and mesoporous ZSM‐5. The results from the SEM, TEM, and N₂ adsorption/desorption isotherms, and ²⁷Al MAS NMR characterisations of the synthesised samples obtained after the removal of the templates confirmed the successful formation of the micro‐ and mesoporous zeolites. The mesoporosity of the zeolites could be controlled by adjusting the carbon content in the SiO₂/C composites while the carbon content could be controlled by varying the deposition time and the concentration of the carbonaceous gases used. This controllable and efficient synthesis method is considered to be a promising method for creating hierarchical micro‐ and mesoporous zeolites. © 2011 Canadian Society for Chemical Engineering     

改性HZSM-5对正己烷芳构化性能的考察

用Ｇａ、Ｚｎ改性的ＨＺＳＭ－５对正己烷的芳构化性能进行了研究。在Ｇａ改性的ＨＺＳＭ－５上，Ｇａ含量存在一最佳值，此时芳烃收率和氢气收率最大。Ｚｎ改性ＨＺＳＭ－５后提高了芳烃收率，催化剂中Ｚｎ含量达一定值后再增加，芳烃收率变化不大；Ｚｎ含量过高，氢解反应加剧。在Ｇａ／ＨＺＳＭ－５中引入Ｎｉ、Ｃｒ或Ｚｎ后提高了芳烃收率，Ｚｎ、Ｃｒ的引入显著提高了Ｇａ／ＨＺＳＭ－５的脱氢功能，Ｎｉ有较强的氢解作用。     

Performance study of modified ZSM‐5 as support for bimetallic chromium–copper catalysts for VOC combustion

The catalytic performance of bimetallic chromium–copper supported over untreated ZSM‐5 (Cr? Cu/Z), ZSM‐5 treated with silicon tetrachloride (Cr–Cu/SiCl₄‐Z) and ZSM‐5 treated with steam (Cr–Cu/H₂O‐Z) is reported. The activity is based on the combustion of ethyl ethanoate and benzene at a feed concentration of 2000 ppm and a gas hourly space velocity (GHSV) of 32 000 h^?1. Due to higher reactivity and larger molecular size compared with that of water molecules, SiCl₄ reacted at the external surface of ZSM‐5 crystals. Cr–Cu/SiCl₄‐Z and Cr–Cu/H₂O‐Z both gave slightly lower conversion and carbon dioxide yield compared with Cr–Cu/Z. This was attributed to larger active metal crystallites formed in the mesopores and narrowing pore mouth and pore intersection by extraframework species. Cr–Cu/SiCl₄‐Z and Cr–Cu/H₂O‐Z both had reduced concentration and strength of acid sites, thus making them less susceptible to deactivation by coking. The coke accumulated by these two catalysts was relatively softer and more easily decomposed in oxygen during catalyst regeneration. Copyright © 2004 Society of Chemical Industry