苯与合成气在ZnAlCrO x &HZSM-5双功能催化剂上一步法制甲苯/二甲苯

与传统的甲醇和苯烷基化反应相比,合成气和苯一步法制甲苯/二甲苯具有苯转化率高,催化剂稳定性好,经济性高等优点。本研究将系列Zn基的金属氧化物与H-ZSM-5分子筛组成双功能催化剂,实现了合成气与苯高效转化为甲苯/二甲苯,并筛选出最优的双功能催化剂为ZnAlCrO _x &H-ZSM-5。原位红外实验发现,单独的合成气在催化剂上的转化较弱,但加入苯之后,苯与甲氧基等中间体的烷基化反应可以有效拉动合成气的转化。这表明,双功能催化剂中金属组分和分子筛组分间的协同作用拉动了该反应的高效进行。通过Zn、Mg、Ga等元素改性H-ZSM-5分子筛,使得分子筛B酸酸量与L酸酸量的比值降低,发现比值的降低有助于苯的转化。其中Zn改性后B酸与L酸的比值降低最为显著,苯转化率增加的也最多。调变反应温度、原料空速、合成气氢碳比可以控制苯的烷基化程度,调节苯烷基化各产物的选择性。ZnAlCrO _x &H-ZSM-5双功能催化剂在压力3MPa、温度400℃的反应条件下,兼具高的苯转化率（90.6%）和甲苯/二甲苯选择性（74.3%）,同时CO有效利用率为33.7%。     

苯与合成气烷基化催化剂的研究进展

对二甲苯（PX）是制备聚酯材料的重要原料,随着我国经济快速发展,对二甲苯的需求日益增长。目前PX主要通过石化路线生产,由于我国石油资源短缺,迫切需要开发基于煤化工路线的PX生产技术。通过苯与合成气烷基化制备PX是一条新的煤化工路线,近年来受到关注。本文综述了苯与合成气烷基化的最新进展,讨论了贵金属（Pt）、铜基氧化物、锌基氧化物（ZnZr、ZnCr）与沸石的复合以及负载和机械混合两类复合方式对催化效果的影响,分析了甲醇合成与烷基化反应的耦合机制以及反应条件的匹配关系;并与其他三种煤制芳烃技术,即合成气制芳烃、甲醇制芳烃以及苯与甲醇烷基化制烷基苯做了对比分析,表明该技术路线具有成本较低和工艺路线短的优势。     

H-beta分子筛催化苯与甲醇烷基化反应性能

采用两种促进剂协同作用改性制得了H-beta分子筛催化剂,通过XRD、BET及Py-IR对催化剂结构、比表面积及酸性变化进行表征,并将催化剂用于苯与甲醇烷基化测试其催化性能。结果表明,在反应压力为常压、反应温度400℃、空速2 h-1和苯与甲醇物质的量比为1∶1的最优条件下,苯转化率达到42. 5%、甲苯选择性为74. 6%,甲苯和二甲苯总选择性达到了94. 5%。基于结构及性能的研究,探讨了催化烷基化反应机理。     

HZSM-5催化剂改性及其催化苯与低浓度乙烯反应的中试研究

苯与低浓度乙烯烷基化制乙苯是实现低浓度乙烯高附加值利用和增产乙苯的高效路线。通过水蒸气和柠檬酸后处理改性方法制备了改性的HZSM-5催化剂，对改性前后的HZSM-5催化剂样品进行了X射线衍射(XRD)、氮气物理吸附-脱附和氨气-程序升温脱附(NH₃-TPD)表征分析，并考察了不同后处理方法改性HZSM-5催化剂的苯与低浓度乙烯烷基化反应的中试性能。结果表明，水蒸气和柠檬酸组合处理能调节催化剂的酸量和酸强度，增大催化剂的孔容和孔径，从而有效提高乙基苯选择性并抑制副反应的发生，降低二甲苯和重组分的生成；在模拟工业反应条件下，由水蒸气和柠檬酸处理改性的HZSM-5催化剂对乙基苯的选择性提高到99.0%，副产物二甲苯质量分数降低到7.7×10^-5，具有工业化应用前景。     

MgO改性HMCM-22分子筛催化苯与甲醇烷基化制甲苯

采用机械湿混法制备了一系列MgO改性的HMCM-22分子筛催化剂,通过XRD、SEM、N₂物理吸/脱附、Py-IR等手段对改性催化剂的晶体结构、表面形貌、孔道变化和酸性酸量等性质进行了表征,发现负载MgO能够有效地调变HMCM-22分子筛的酸性,但对其孔道的调节效果较弱。采用微反装置评价催化剂性能,在进料比为1∶1、常压、温度为400℃、反应时间4h、质量空速WHSV=10h^-1的条件下,考察了不同MgO负载量下的MgO/HMCM-22催化性能,研究发现MgO负载量介于3%~6%的MgO/HMCM-22催化剂具有优越的催化性能,苯转化率＞50%,甲苯选择性＞60%。同时在该反应条件下,对3%MgO/HMCM-22催化剂的稳定性进行了考察,结果表明,反应40h内,苯的转化率始终保持在50%以上;反应至第80h时,苯的转化率仍然可达23%,且甲苯选择性始终保持在65%左右。     

双功能催化剂在合成气一步法制低碳烯烃中的研究进展

双功能催化剂能够有效地突破费托合成中烯烃选择性限制,实现了高的低碳烯烃选择性,成为合成气一步法制低碳烯烃的研究热点。详细综述了近五年来金属氧化物/分子筛双功能催化剂的制备、构效关系、催化机理的研究进展,并对双功能催化剂的进一步发展方向进行了展望。     

双功能催化剂在合成气一步法制低碳烯烃中的研究进展

双功能催化剂能够有效地突破费托合成中烯烃选择性限制,实现了高的低碳烯烃选择性,成为合成气一步法制低碳烯烃的研究热点.详细综述了近五年来金属氧化物/分子筛双功能催化剂的制备、构效关系、催化机理的研究进展,并对双功能催化剂的进一步发展方向进行了展望.     

苯与长链烯烃烷基化反应催化剂的研究进展

催化剂是决定烷基化反应技术水平的关键因素之一,本文从催化剂的催化活性,产品中直链烷基苯的选择性,催化剂的使用寿命等方面评价了现有的各种催化剂,并介绍了包括杂多酸、分子筛、离子溶液等各种新型改性催化剂的研制开发。提出今后应进一步深入研究包括杂多酸在内的符合环保要求和工业化需求的新型改性催化剂。     

合成气制二甲醚双功能催化剂的研究进展

综述了二甲醚的物化特性以及其作为新型替代能源的广阔应用前景.对现有的几种不同的合成气一步法合成二甲醚的反应机理及动力学模型进行了概述.并分别介绍了双功能催化剂中的甲醇合成催化组分、甲醇脱水催化组分的研发现状及进展.CuO/ZnO/Al2O3作为甲醇合成组分技术已经比较成熟,甲醇脱水活性组分以γ-Al2O3、分子筛及其改性后产物最为常用.探讨了双功能催化剂的制备方法及改性方法的研究,这也将成为今后合成气一步法制二甲醚技术的研究热点.     

甲苯甲醇烷基化反应催化剂改性HZSM-5分子筛的研究进展

甲苯甲醇烷基化具有甲苯利用率高,产物选择性高等特点,是一条很有应用前景的合成路线。综述了改性后的HZSM-5分子筛催化剂用于甲苯甲醇烷基化反应的研究进展,通过负载元素改性或是在HZSM-5分子筛上生长Sillicalite-1层的改性方法,减小孔径或缩小孔口,屏蔽ZSM-5分子筛外表面的酸性位,可提高产物对二甲苯的选择性。     

Alkylation of benzene with carbon dioxide to low-carbon aromatic hydrocarbons over bifunctional Zn-Ti/HZSM-5 catalyst

Alkylation of benzene to value-added,high octane number and low toxic toluene and xylenes provides a way to lower benzene content in gasoline pool,and is hence a method to promote fuel quality.On the other hand,CO₂ accumulation in the atmosphere causes global warming and requires effective route for its valorization.Utilization of CO₂ as a carbon source for benzene alkylation could achieve both goals.Herein,alkylation of benzene with CO₂ and H2 was realized by a series of low-cost bifunctional catalysts containing zinc/titanium oxides(Zn/Ti oxides)and HZSM-5 molecular sieves in a fixed-bed reactor.By regulating and controlling oxygen vacancies of Zn/Ti oxides and the acidities of HZSM-5,benzene conversion and CO₂ conversion reached 28.7%and 29.9%respectively,along with a total selectivity of toluene and xylene higher than 90%.In this process,more than 25%CO₂ was effectively utilized and incorporated into the target products.Moreover,the mechanism of the reaction was analyzed and the course was simultaneously traced.CO₂ was transformed into methanol firstly,and then methanol reacted with benzene generating toluene and xylene.The innovation provides a new method for upgrading of fuels and upcycling the emissions of CO₂,which is of great environmental and economic benefits.     

ZnxZr/HZSM-5 as efficient catalysts for alkylation of benzene with carbon dioxide

Alkylation of benzene with carbon dioxide and hydrogen to produce toluene and xylene could increase the added-value of surplus benzene as well as relieve environmental problems like green-house effect. In this work, the alkylation benzene with carbon dioxide and hydrogen reaction was proceeded by using the mixture of zinc-zirconium oxide and HZSM-5 as bifunctional catalyst. The equivalent of Zn/Zr = 1 displays the best catalytic performance at 425 °C and 3.0 MPa, and benzene conversion reaches 42.9% with a selectivity of 90% towards toluene and xylene. Moreover, the carbon dioxide conversion achieves 23.3% and the carbon monoxide selectivity is lower than 35%, indicating that more than 50% carbon dioxide has been effectively incorporated into the target product, which is the best result as far as we know. Combined with characterizations, it indicated that the Zn and Zr formed a solid solution under specific conditions (Zn/Zr = 1). The as-formed solid solution not only possesses a high surface area but also provides a large amount of oxygen vacancies. Additionally, the bifunctional catalyst has excellent stabilities that could keep operating without deactivation for at least 80 h. This work provides promising industrial applications for the upgrading of aromatics.     

HZSM-5择形催化剂上乙苯烷基化反应生产对二乙苯的研究

针对乙苯与乙烯烷基化法生产对二乙苯的工艺过程,利用1 500 t/a对二乙苯的工业装置,对装有镁改性HZSM-5分子筛的固定床反应器中的乙苯烷基化反应工艺条件进行了研究。考察了反应温度、空速和原料质量比对反应的影响,并进行了分析和讨论。结果表明,在不同的工艺条件下,产物中邻、间二乙苯的质量分数均随对二乙苯的质量分数升高而升高,但间、邻二乙苯质量分数过高,增加了产品分离的难度,很难得到高纯度的对二乙苯产品。乙苯的转化率及反应产物中邻、间、对二乙苯的质量分数均随着反应温度的升高,在保证产品质量的前提下,375℃为适宜的反应温度。在乙苯循环反应过程中,乙苯质量空速应在3 h-1左右,同时乙苯与乙烯的原料质量比不宜过大,在17左右适宜。     

Catalytic kinetics of dimethyl ether one-step synthesis over CeO_2–CaO–Pd/HZSM-5 catalyst in sulfur-containing syngas process

CeO_2–CaO–Pd/HZSM-5 catalyst was prepared for the dimethyl ether(DME) one-step synthesis in a continuous fixed-bed micro-reactor from the sulfur-containing syngas. The catalytic stability over hybrid catalyst of CeO_2–CaO–Pd/HZSM-5 was investigated to ensure that the kinetics experimental results were not significantly influenced by induction period and catalytic deactivation. A large number of kinetic data points(40 sets) were obtained over a range of temperature(240–300 °C), pressure(3–4 MPa), gas hourly space velocity(GHSV)(2000–3000 L·kg~(-1)·h~(-1)) and H_2/CO mole ratio(2–3). Kinetic model for the methanol synthesis reaction and the dehydration of methanol were obtained separately according to reaction mechanism and Langmuir–Hinshelwood mechanism. Regression parameters were investigated by the method combining the simplex method and Runge–Kutta method. The model calculations were in appropriate accordance with the experimental data.     

过渡金属改性对MgO/ZSM-5催化剂苯-甲醇烷基化性能的影响

采用过渡金属对2.5%Mg O/ZSM-5催化剂进行负载改性,考察其苯-甲醇烷基化性能,结果表明,Ni和Fe改性催化剂因改性后弱酸量大幅增加,苯转化率提高,分别为56.6%和55.8%;W和Mn改性催化剂二甲苯选择性较高,约为35%;与其他改性催化剂相比,Co和Mo改性催化剂上的苯转化率和二甲苯选择性没有明显优势。选择改性效果较好的双金属催化剂进行苯-甲醇烷基化高空速(15 h-1)长时间运转实验,催化剂初始活性均大于57%,反应20 h时,苯转化率约50%,20 h后烷基化活性迅速下降,是由于催化剂积炭失活所致。     

Influence of the post-treatment of HZSM-5 zeolite on catalytic performance for alkylation of benzene with methanol

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 alkyl-ation 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 Br?nsted 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.     

改性HZSM-5上焦化苯与乙醇烷基化制乙苯

通过离子交换法制备硼改性的分子筛,并在连续固定床反应器上对其进行焦化苯与乙醇烷基化反应催化性能和脱硫性能的考察。通过XRD和BET方法对催化剂进行表征,结果表明,改性后催化剂的比表面积、微孔孔容和孔径均减少。反应评价结果显示,改性后乙苯选择性略有降低,苯转化率增加。最佳反应条件：温度（350～400） ℃,n(苯)∶n(乙醇)=(3∶1)～(5∶1),空速（4～6） h^-1。