改性ZSM-5催化剂上苯与FCC干气中乙烯气相烷基化反应

考察了经过改性的ZSM-5沸石和参比催化剂催化苯与流化催化裂化(FCC)干气中乙烯的气相烷基化反应.结果表明,改性ZSM-5催化剂的乙基化选择性高于参比催化剂,产物中的二甲苯和总杂质含量小于参比催化剂,稳定性优于参比催化剂.通过考察比较改性ZSM-5沸石催化剂与参比催化剂在苯与稀乙烯气相烷基化反应的工艺条件,获得了匹配于该改性ZSM-5沸石催化剂的较佳工艺条件:反应温度350～380℃,反应压力0.5～0.9 Mpa.苯烯物质的量比4.0～7.0,乙烯空速0.4～0.7 h-1.并在选定的优化工艺条件下分别对改性催化剂和参比催化剂进行了1 000 h的寿命实验.结果显示,在1 000 h寿命实验内,反应产物中乙苯含量没有下降的趋势,改性催化剂和参比催化剂的乙烯转化率分别为99.99%和99.96%,乙基化选择性分别为80%和77%,二甲苯含量分别为871和2 223 mg/kg左右.     

气相法乙苯清洁生产工艺技术进展

随着乙苯需求不断增加,乙苯工艺的开发和应用也不断进步。20多年来,我国气相法乙苯清洁生产工艺技术经历了由国外引进到催化剂国产、再到成套技术自主创新的发展历程。中国科学院大连化学物理研究所开发了用于气相法干气制乙苯的ZSM-5/ZSM-11分子筛催化剂,中国石化上海石油化工研究院开发了一系列以ZSM-5分子筛为活性组分的气相法制乙苯催化剂,我国乙苯总产能已跃居世界首位,其中,采用气相法催化剂及工艺技术的装置规模达2 410 kt·a-1,催化剂性能和工艺技术指标达到世界先进水平,所用原料也由纯乙烯拓展到稀乙烯和乙醇。在气相法工艺大规模推广的同时,对现有技术的改进、新催化剂和新工艺技术的开发工作也在进行中,未来气相法乙苯生产工艺的能耗将进一步降低,原料普适性也更好。     

从催化裂化干气中吸收丙烯

针对催化裂化干气制乙苯技术的发展和干气中丙烯对催化剂及成套技术的影响进行了对干气中丙烯选择吸收以降低其中丙烯含量的研究.通过苯、乙苯、柴油、反烃化料和乙苯/反烃化料等吸收剂对干气中丙烯吸收效果对比,表明,采用m(乙苯)/m(反烃化料)混合料对干气中丙烯吸收效果最理想.采用低温和高吸收剂/干气体积比有利于乙苯/反烃化料的混合物吸收剂对干气中丙烯的吸收,且吸收剂吸收后的气体在一定的条件下可解吸,解吸后的吸收剂可循环使用,利用吸收后的催化裂化干气制乙苯可明显降低苯耗和提高乙基化产物选择性.     

空壳型ZSM-5分子筛用于苯-乙醇烷基化制乙苯的研究

选用空壳型ZSM-5分子筛为母体催化剂,利用固定床反应器考察了煤基乙醇与苯烷基化制备乙苯反应条件对催化性能的影响,并在优化条件下评价空壳型HZSM-5母体催化剂的反应稳定性;研究了水热处理与P或Zn单组分对母体ZSM-5联合改性所得催化剂的烷基化催化性能。结果表明,空壳型HZSM-5母体催化剂用于苯与乙醇烷基化反应,连续反应100 h性能基本没有变化,苯转化率保持在13.4%左右、乙基选择性为97.8%,而二甲苯相对质量分数保持在3 400μg/g。经过单组分改性与水热处理联合改性的空壳型HZSM-5分子筛,可以进一步提高乙基选择性和降低二甲苯杂质质量分数,在苯/乙醇摩尔比为6、反应温度为340℃和空速为6 h^-1的优化条件下,苯转化率大于10%,乙基选择性大于99%,二甲苯相对质量分数低于700μg/g,具有很好的应用开发潜力。     

催化裂化轻汽油在ZSM-5分子筛催化剂上裂化反应的研究

以ZSM-5分子筛为催化剂，在小型固定床反应器上，进行了催化裂化轻汽油的裂化反应。考察了反应温度和空速对催化裂化轻汽油裂化反应气液相收率和产品分布的影响。实验结果表明，ZSM-5分子筛催化剂具有较强的裂化活性和氢转移活性。在保证裂化转化率的条件下，提高反应温度和空速可以抑制催化剂上氢转移反应的发生。以ZSM-5分子筛为催化剂上的催化裂化反应中，温度、空速是影响转化率和选择性的重要因素，因此可以通过改变温度、空速来提高目的产物的选择性。但是，单纯依靠改善反应条件，不能使目的产物的收率和选择性达到理想的程度，还必须对催化剂进行改性。ZSM-5分子筛催化剂上催化裂化反应的研究为ZSM-5分子筛催化剂的进一步改性，及ZSM-5分子筛催化剂在轻汽油催化裂解和汽油改质方面的进一步应用提供了试验依据。     

SEB-08催化剂在干气制乙苯装置的工业应用

中国石油化工股份有限公司广州分公司采用新一代SGEB气相法干气（稀乙烯）制乙苯技术,建成一套年产85 kt干气制乙苯装置。烷基化催化剂使用中国石油化工股份有限公司上海石油化工研究院研制的SEB-08稀乙烯制乙苯催化剂。运行结果表明,SEB-08催化剂可适用不同浓度的稀乙烯原料,具有较强的抗工艺波动能力,原料循环苯中甲苯含量对二甲苯的产生有较大影响,必须严格控制循环苯中甲苯含量;标定结果表明,在反应器入口温度344 ℃、入口压力0.86 MPa、苯与乙烯物质的量比6.71、乙烯质量空速0.297 h^-1和装置反应负荷109%条件下,乙烯转化率为99.73%,乙基选择性为99.65%,二甲苯含量为848×10^-6。SEB-08催化剂具有处理量大、活性高、选择性和稳定性好等优点,有利于提供现有干气制乙苯装置的生产能力。     

正十二烷在Pt/ZSM-22和Pt/ZSM-23上的加氢异构反应性能

采用常规水热合成法合成了ZSM-22和ZSM-23分子筛,进而制备了分别含有上述分子筛的催化剂,并借助XRD、SEM、NH3-TPD和Py-IR表征了这两种分子筛和催化剂的结构和酸性,同时以正十二烷为模型化合物,采用固定床反应器研究了Pt/ZSM-22和Pt/ZSM-23催化剂上正十二烷加氢异构反应性能。结果表明,在这种模型反应基础上,催化剂的反应活性和选择性主要取决于催化剂的酸量和酸强度以及酸分布,相对而言,ZSM-22分子筛催化剂由于其弱酸和中等强度酸的含量较高,具有更佳的异构化选择性。     

SEB-08催化剂在干气制乙苯装置的工业应用

烷基化催化剂SEB-08在中海油东方石化有限责任公司120 kt/a干气制乙苯装置的应用情况。该催化剂在开工过程中不需要活化,开工容易。此外,该催化剂还具有较高的活性与稳定性,主要体现在该催化剂反应起始温度低,再生周期较长。催化剂在该装置的运行结果表明,控制反应干气中丙烯含量低于300 mg/kg,严格控制循环苯中非芳和甲苯含量处于较低水平,乙苯产品中二甲苯含量、苯耗等都处在较低水平,表明该催化剂具备良好的选择性。     

催化裂化干气中乙烯制乙苯绝热反应温升和去热方式

本文介绍催化裂化干气中乙烯与苯制乙苯过程反应热平衡,讨论了进料乙烯浓度和苯/乙烯比与反应温升的关系,并论述了烃化反应器分层注入催化干气或苯的取热方式。结果表明,能有效地降低温升,确保催化剂处于最佳温区操作。     

稀土改性ZSM-5分子筛催化乙苯合成的研究

在ZSM-5分子筛水热合成过程中引入适量的稀土氧化物,制备了系列分子筛催化剂,并对其进行了XRD,NH3-TPD表征,考察了其在苯与乙醇反应过程中的催化性能。结果表明:适量稀土氧化物的引入,对于分子筛的骨架结构无明显影响,可以合成出较高结晶度的ZSM-5分子筛;催化剂酸强度无显著影响,总酸量降低;苯与乙醇的反应活性稍有下降,但乙苯选择性明显提高,并表现出优于HZSM-5的催化活性,具备一定的工业应用前景。     

Ethylbenzene disproportionation and p-xylene selectivity enhancement in xylene isomerization using high crystallinity desilicated H-ZSM-5

Desilication accompanied with minimum loss of crystallinity effect of a high alumina ZSM-5 zeolite on the isomerization reaction of ethylbenzene/xylene mixtures has been considered.Desilication was assessed through XRF,XRD,FTIR,TEM,nitrogen adsorption/desorption,NH_3-TPD,~(29)Si and~(27)Al MAS NMR analytical techniques.Desilication was accompanied with the creation of super acid sites.There exists a limit(Si/Al molar ratio of9.67)for keeping high crystallinity and obtaining improved catalytic performance.Desilication promotes ethylbenzene conversion by disproportionation and trans-alkylation reactions while the same reactions are limited for the xylene isomers.The p-xylene approach to equilibrium improves by more than 7% at 400℃ and a WHSV of 2 h~(-1)for the optimum sample with respect to the parent zeolite.At the same conditions,the optimum sample exhibits the maximum ethylbenzene conversion of 89%,i.e.more than 40%w.r.t.of the parent zeolite.However,the xylene yield decreases only 3%.     

含分子筛重整催化剂反应性能研究

对含有ZSM-5沸石的重整催化剂的催化性能进行了研究。结果表明,ZSM-5催化剂具有比常规重整催化剂更高的芳构化活性,并且产物中苯和二甲苯的含量较高,对二甲苯的含量高于其热力学平衡含量。当锌的质量分数为3.0%时,表现出更好的催化性能,铂的增加对重芳烃的产生具有明显的抑制作用。     

Co-conversion of methanol and n-hexane into aromatics using intergrown ZSM-5/ZSM-11 as a catalyst

The conversion of n-hexane and methanol into value-added aromatic compounds is a promising method for their industrially relevant utilization. In this study, intergrown ZSM-5/ZSM-11 crystals were synthesized and their resulting catalytic performance was investigated and compared to those of the isolated ZSM-5 and ZSM-11 zeolites. The physicochemical properties of ZSM-5/ZSM-11 intergrown zeolite were analyzed using X-ray diffraction, N₂ isothermal adsorption-desorption, the temperature-programmed desorption of ammonium, scanning electron microscopy, Fourier transform infrared spectra of adsorbed pyridine, and nuclear magnetic resonance of ²⁷Al , and compared with those of the ZSM-5 and ZSM-11 zeolites. The catalytic performances of the materials were evaluated during the co-feeding reaction of methanol and n-hexane under the fixed bed conditions of 400°C, 0.5 MPa (N₂), methanol:꞉n-hexane=7꞉:3 (mass ratio), and weight hourly space velocity=1 h^–1 (methanol). Compared to the ZSM-5 and ZSM-11 zeolites, the ZSM-5/ZSM-11 zeolite exhibited the largest specific surface area, a unique crystal structure, moderate acidity, and suitable Brønsted/Lewis acid ratio. The evaluation results showed that ZSM-5/ZSM-11 catalyst exhibited better catalytic reactivity than the ZSM-5 and ZSM-11 catalysts in terms of methanol conversion rate, n-hexane conversion rate, and aromatic selectivity. The outstanding catalytic property of the intergrown ZSM-5/ZSM-11 was attributed to the enhanced diffusion associated with its unique crystal structure. The benefit of using zeolite intergrowth in the co-conversion of methanol and alkanes offers a novel route for future catalyst development.     

含分子筛重整催化剂的反应性能研究

对含有ZSM-5沸石重整催化剂的催化性能进行了研究,结果表明,ZSM-5催化剂具有比常规重整催化剂更高的芳构化活性,并且产物中苯和二甲苯的含量较高,对二甲苯的含量高于其热力学平衡含量。当催化剂中锌质量分数为2.0%时,表现出更好的催化性能,铂的增加对重芳烃的产生具有明显的抑制作用。     

Benzene alkylation with methanol over phosphate modified hierarchical porous ZSM-5 with tailored acidity

The acidity and acid distribution of hierarchical porous ZSM-5 were tailored via phosphate modification.The catalytic results showed that both benzene conversion and selectivity of toluene and xylene increased with the presence of appropriate amount of phosphorus.Meanwhile,side reactions such as methanol to olefins related with the formation of by-product ethylbenzene formation and isomerization of xylene to meta-xylene were suppressed efficiently.The acid strength and sites amount of Br(o)nsted acid of the catalyst were crucial for improving benzene conversion and yield of xylene,whereas passivation of external surface acid sites played an important role in breaking thermodynamic equilibrium distribution of xylene isomers.     

Coke burning behavior of a catalyst of ZSM-5/ZSM-11 co-crystallized zeolite in the alkylation of benzene with FCC off-gas to ethylbenzene

Since the commercialization of ethylbenzene production via alkylation of benzene with the dilute ethene in FCC off-gas over a ZSM-5/ZSM-11 co-crystallized zeolite catalyst in China, the catalyst has been regenerated several times and showed good regeneration performance. During the alkylation process, the catalytic activity decreases, some of the catalyst pores are blocked and the acid centers are partly covered by coke deposition. Influence of the factors such as catalyst particle size, temperature, etc. on the burning rate of the coke was investigated by the TG technique, and a rate equation for coke burning on the ZSM-5/ZSM-11 co-crystallized catalyst was established.     

Differences between ZSM-5 and ZSM-11 zeolite catalysts in 1-hexene aromatization and isomerization

ZSM-5 and ZSM-11 zeolites with high crystallinity are synthesized and tested in the aromatization and isomerization reactions of 1-hexene at 370 °C in a continuous flow fixed bed. The results indicate that ZSM-5 and ZSM-11 zeolites possess similar acid site amount and strength, and most of the acid sites belong to Brønsted acid. When the ZSM-5 and ZSM-11 zeolites were used as catalysts, the aromatics selectivity over ZSM-11 catalyst was higher than that over ZSM-5 catalyst in contrast to i-paraffins selectivity, maybe attributed to that the C₇ and C₈ aromatics have an easier exit from the ZSM-11 zeolite. Moreover, the decrease of particle size can present superior aromatics selectivity and less i-paraffins selectivity in the aromatization and isomerization of 1-hexene over the ZSM-11 catalyst.     

甲苯甲醇烷基化制对二甲苯催化剂中试反应性能研究

经过多步改性制备了负载二氧化硅（SiO₂）、氧化镁（MgO）、五氧化二磷（P₂O₅）、贵金属铂（Pt）的纳米ZSM-5分子筛催化剂,并在六段固定床反应器上分段装填该催化剂720 g进行甲苯、甲醇烷基化制对二甲苯反应活性评价。实验结果表明,通过调变甲醇和甲苯物质的量比可以使甲苯转化率在22%~30%可调,烷基化液相产物中二甲苯选择性保持在95%以上,二甲苯中对二甲苯选择性保持在95%以上;催化剂单程寿命达到1 300 h,随着反应时间延长催化剂的活性有所下降。通过X射线衍射（XRD）、热重分析（TG-DTG）和氮气吸附-脱附等手段对参加反应前后的催化剂进行了表征,结果表明反应中生成的积炭堵塞了分子筛的孔道或覆盖了催化剂的活性位;经过在反应器内原位再生,催化剂的反应活性基本恢复到新鲜催化剂水平。     

SYNTHESIS OF ZSM-5 FROM MODIFIED CLINOPTILOLITE AND ITS CATALYTIC ACTIVITY IN ALKYLATION OF BENZENE TO ETHYLBENZENE

ZSM-5 catalysts were prepared by utilizing clinoptilolite found in Western Anatolia in abundant amounts as a type of natural zeolite. Hydrothermal reaction was conducted with HCl-treated clinoptilolite at 180°C. After characterizing the solid products obtained by this reaction as ZSM-5 by means of XRD, IR, TGA, surface area analyzer, and chemical analysis they were tested as catalysts in benzene alkylation reaction with ethylene leading to ethylbenzene. Catalytic performance of samples prepared in this study was investigated for benzene conversion, ethylbenzene yield, and selectivity. It was found that ZSM-5(A) sample showed performance similar to that of the reference sample (ZSM-5(C)) synthesized by using patented literature information in terms of benzene conversion. When the reaction temperature was increased from 400° to 425°C ethylbenzene yield and selectivity results of ZSM-5(A) sample were improved but coke formation increased. Catalyst test results indicated the possibility of using clinoptilolite as a raw material in the synthesis of ZSM-5 catalyst for alkylation of benzene with ethylene reaction.