磷改性ZSM-5分子筛催化裂解石脑油制丙烯的性能研究

以催化重整石脑油为原料,以水热处理磷改性HZSM-5为催化剂,在小型固定床反应装置上,考察了水热处理磷改性方法制备催化剂的催化裂解性能。结果表明,磷改性HZSM-5经水热处理后与未改性HZSM-5相比,水热稳定性明显改善,当磷负载量为3%wt时,PZSM-5具有较高的活性和丙烯选择性。催化裂解反应过程中选择适宜的工艺条件可有效的抑制副反应的发生。综合考虑丙烯及双烯收率,确定最佳的反应条件为:温度650℃,体积空速4h-1,水油体积比0.75,反应压力0.2MPa。     

用于甲苯甲醇烷基化制备对二甲苯反应的ZSM-5分子筛改性研究

甲苯甲醇烷基化制备对二甲苯具有良好的工业应用前景,ZSM-5分子筛由于其特殊的结构在该反应中展现出优异的催化性能,对ZSM-5分子筛进行改性研究,有助于提升其催化性能。本文从引入金属与非金属元素改性方面综述了国内外对ZSM-5分子筛改性用于甲苯甲醇烷基化制对二甲苯反应的研究进展。     

磷铝复合改性ZSM-5分子筛及其催化性能

ZSM-5分子筛是一种重要的高硅铝比择形催化剂,具有较强的酸性和较好的热、水热稳定性,通过对该分子筛进行磷与铝的复合改性,对其酸性质和孔结构进行了调变。研究结果表明,当磷铝负载量（质量分数）大于10%时,磷铝物种以片状形式沉积在ZSM-5分子筛表面,不仅提高了分子筛的酸量,还形成了孔径在10 nm左右的介孔。这种高酸性的多级孔结构使其正辛烷裂化转化率明显提高,丙烯收率增加20%以上;在重油催化裂化评价反应中降低了渣油和焦炭收率,丙烯的收率提高了1%。     

磷改性ZSM-5分子筛及其在催化增产丙烯中的应用研究进展

ZSM-5分子筛具有良好的催化活性和择型性,常被作为催化剂或助剂活性组分广泛应用于丙烯生产过程,但其在高温水热反应过程中存在易失活的问题.使用磷元素对ZSM-5分子筛进行改性能够有效改善其酸性并提高其水热稳定性,进而减少催化剂的失活.综述了磷改性ZSM-5分子筛机理的研究进展,分析了改性方法、改性磷质量分数和分子筛硅铝...     

磷改性对ZSM-5分子筛石脑油催化裂解性能的影响

以HZSM-5分子筛为载体,以磷酸氢二铵为磷源,采用等体积浸渍法制备了磷改性ZSM-5分子筛,采用吡啶吸附红外光谱法研究了磷改性ZSM-5分子筛的酸性及水热稳定性,在小型固定床反应装置上进行了石脑油催化裂解反应研究.结果表明,适量磷(3％)改性显著改善了ZSM-5分子筛的酸性和水热稳定性,提高了ZSM-5分子筛催化剂的...     

甲苯在硅沉积结合水热改性ZSM-5分子筛上的选择性歧化

采用液相沉积法研究了硅改性剂结合水热改性对择形分子筛的表面酸性和孔结构参数的影响。以甲苯的歧化反应为探针，考察了改性剂的种类和改性次数等因素对催化剂选择性和活性的影响。结果表明，硅改性剂能显著改变分子筛的强酸性，可以对择形分子筛的孔结构进行精细调节。分子筛改性后甲苯的转化率有所降低，但对二甲苯的选择性明显提高。     

磷改性ZSM-5分子筛物化性质和裂解制乙烯性能的研究

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 P205 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.     

分子筛ZSM-5的改性研究进展

介绍了ZSM-5分子筛的相关知识,阐述了对其改性的必要性。基于改性原理,从金属改性、复合改性和其他改性三方面综述了国内分子筛ZSM-5的改性研究进展,重点介绍了ZSM-5表面功能化后金属改性和复合改性的方法。评述了金属改性、预掺杂和后掺杂对改性的ZSH-5催化剂催化性能的影响。     

用于MTP反应ZSM-5分子筛的磷改性研究

将P改性用于甲醇制丙烯(MTP)反应ZSM-5分子筛的改性研究,以提高丙烯选择性和分子筛活性稳定性。采用XRD、SEM和NH_3-TPD表征催化剂物化性能。对不同硅铝比ZSM-5分子筛P改性研究发现,3种不同硅铝物质的量比(50、150和300)ZSM-5分子筛进行P改性时,在n(P)∶n(Al)=0.5~0.7时,ZSM-5分子筛改性后丙烯选择性和寿命得到提升。研究分子筛晶粒尺寸与P负载量关系时发现,随着分子筛晶粒尺寸的增大,位于分子筛表面的P含量逐渐增加,并且分子筛晶粒越小,最佳的P负载量越小。     

磷改性ZSM-5分子筛在甲醇制芳烃反应中催化性能的固体核磁研究

甲醇制芳烃反应在化工领域具有重要的现实意义,ZSM-5分子筛是这一反应的优良催化剂,磷改性是提高ZSM-5分子筛催化性能的常见方法。利用固体核磁共振技术对改性催化剂进行1H、27Al和31P表征,结合催化考评结果,推测或论证影响催化活性的因素,对反应条件的优化提出有益的帮助和支持。     

聚苯基甲基硅氧烷改性ZSM-5分子筛上的甲苯择形歧化反应

以聚苯基甲基硅氧烷为改性剂,采用化学液相沉积法对ZSM-5分子筛催化剂进行改性修饰,考察改性催化剂的甲苯择形歧化反应性能。采用XRD、BET、NH 3-TPD表征改性催化剂的孔结构和酸性质。结果表明,聚苯基甲基硅氧烷作为改性剂可以增加催化剂的弱酸中心和中强酸中心酸量,同时缩小催化剂的平均孔径,改性程度与改性次数有关。改性催化剂用于甲苯歧化反应可以增加对二甲苯的选择性,对二甲苯选择性的增加程度与改性次数有关,改性次数增多,对二甲苯选择性增加越显著,同时甲苯转化率越低,副反应越多。     

Roles of ZSM-5 modifier agents in selective toluene disproportionation

Selective toluene disproportionation has been studied over ZSM-5 zeolites modified with P, Si and Cs compounds. For the P and Si modified samples, p-xylene proportion in the primary product was 100% due to the diffusional control on the internal xylene isomerization. The number and strength of the acid sites are reduced by the three modifier agents but a relationship between para-selectivity and the decrease of the acid strength has not been observed. The most para-selective samples have been those modified with Si which has been related to the deposition of this agent on the external surface of the zeolite crystals avoiding the primary product isomerization.     

Selective toluene disproportionation over ZSM-5 zeolites

Selective toluene disproportionation to benzene and xylenes is investigated over HZSM-5 and modified HZSM-5 zeolites. The zeolites are modified with nickel, magnesium, phosphorus and boron, characterised by sorption, acidity measurement and X-ray photoelectron spectroscopy, and their activity towards toluene disproportionation is discussed in the light of their physico-chemical properties. The two types of active sites have been identified; one promoting disproportionation and the other cracking and dealkylation of toluene. It is found that the latter sites are suppressed due to incorporation of the modifiers. The modified zeolites are found to be para-selective which appears to be consistent with the commonly accepted view that modifiers like magnesium, phosphorus and boron reside in the channels and react with Brønsted acid sites, leading to partial blockages and thus favouring the formation of p-xylene. The effect of poisoning the zeolite with 1-methylisoquinoline is also investigated. In the case of poisoned catalyst, p-xylene is produced at levels up to 99%. The total elimination of other isomers from the products is suggested due to the selective poisoning of the non-selective sites (on the external crystal surface) and to partial blocking of the pore openings.     

磷镁改性HZSM-5催化剂甲苯甲醇烷基化性能研究

采用浸渍法制备了系列磷镁改性ZSM-5催化剂，考察了磷镁改性对HZSM-5催化剂甲苯甲醇烷基化反应活性和选择性的影响。并对其进行了NH3-TPD，Py—IR，XRD等表征，研究了改性氧化物在ZSM-5分子筛表面的分布状态以及其对催化剂的酸性质的影响，结果表明磷元素改性有效降低了催化剂的酸强度，抑制了甲苯歧化反应；MgO质量含量低时，主要以无定形状态高度分散在分子筛外表面上，含量较高时形成结晶态MgO。MgO改性主要作用是覆盖了催化剂外表面酸性活性中心，堵塞了孔口，提高了反应产物的对位选择性。     

磷改性ZSM-5沸石的催化裂化性能

用磷改性ZSM-5沸石,并将其制备成催化剂。初步考察了其物化性能的变化,并在固定床重油微反装置上考察了其催化裂化反应特性。研究发现,磷能显著改善ZSM-5沸石的活性、稳定性和选择性。ZSM-5沸石上不同的磷含量和其与不同的Y型分子筛配伍对催化裂化反应有着显著的影响。合理调配催化裂化催化剂的活性组分,适当控制其氢转移能力和烷基化能力,对增产丙烯有着积极的意义。     

TEOS-化学液相沉积法改性ZSM-5催化剂上的高选择性甲苯择形歧化反应

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.     

改性ZSM-5分子筛催化合成哌嗪

研究了不同金属离子改性得到的M-ZSM-5分子筛在以乙二胺(EDA)为原料合成哌嗪反应中的催化性能。通过NH3-TPD和BET法对催化剂进行表征,结果表明,经过离子交换后HZSM-5的骨架结构没有发生变化,仅仅是表面酸性发生了变化。重点考察了催化剂酸性对反应的影响,实验表明,提高弱酸和中强酸中心所占比例有利于哌嗪(PA)和三乙烯二胺(TEDA)生成。以Zn-ZSM-5和Zn/K-ZSM-5为催化剂,在常压,t=360℃,空速为0.25 g/(min.h),m(EDA)∶m(H2O)=4∶6的反应条件下,原料EDA的转化率分别为94.1%和82.6%;产物PA和TEDA的选择性分别为45.5%,42.1%和29.4%,50.1%。     

不同晶粒形貌ZSM-5分子筛的表征及催化甲苯歧化反应

制备不同晶粒形貌的ZSM-5分子筛,采用XRD、SEM和NH_3-TPD对合成的分子筛催化剂进行表征,并用于甲苯歧化反应考察其催化性能。结果表明,制备的ZSM-5分子筛具有六角板状、棒状和球状3种晶粒形貌,棒状分子筛暴露较多的(101)晶面,六角板状分子筛暴露较多的(020)晶面,棒状分子筛具有较高的强酸量。在甲苯歧化反应中,ZSM-5分子筛催化剂暴露(101)晶面越多,产物扩散可能性越大,导致甲苯转化率提高,强酸量增加使副反应发生可能性增大,降低二甲苯选择性。