甲醇制烯烃反应积炭调控与分子筛催化剂改性研究进展

从SAPO-34分子筛催化剂在甲醇制烯烃(MTO)反应中的积炭行为与形成机理出发,分析了积炭对催化剂、MTO反应及在工业应用中的影响,以催化剂改性和工艺技术两个角度系统总结了现有MTO反应过程中积炭调控的主要方式,为新型催化剂的开发及工艺技术优化提升提供了研究依据和参考.     

甲醇制烯烃反应积炭调控与分子筛催化剂改性研究进展

从SAPO-34分子筛催化剂在甲醇制烯烃(MTO)反应中的积炭行为与形成机理出发,分析了积炭对催化剂、MTO反应及在工业应用中的影响,以催化剂改性和工艺技术两个角度系统总结了现有MTO反应过程中积炭调控的主要方式,为新型催化剂的开发及工艺技术优化提升提供了研究依据和参考。     

甲醇制烯烃反应SAPO-34催化剂积炭行为的原位漫反射红外光谱分析

依据酸性催化剂表面吸附态物种分子产生红外信号的机理,采用原位漫反射红外光谱技术对甲醇制烯烃反应中不同反应时间与床层位置的SAPO-34催化剂积炭行为进行研究。结果表明,反应时间与床层位置的变化对SAPO-34催化剂积炭数量和物种有显著影响。反应时间延长导致SAPO-34催化剂积炭量增加,且积炭成分中重组分稠环芳烃比例上升,积炭速率逐渐加快。积炭量随床层位置自上而下逐渐减少,失活催化剂笼中烷基芳香烃类积炭通过环化和脱氢逐渐转变为多环芳香烃类。     

甲醇制烯烃催化剂失活机理的研究进展

综述了甲醇制低碳烯烃(MTO)过程中吸附、扩散和反应过程对催化剂失活的影响,其中催化剂表面积炭是MTO工艺失活的主要因素,同时介绍了甲醇催化转化低碳烯烃过程催化剂结构对反应活性和选择性的影响。     

甲醇制烯烃催化剂薄层成型技术研究

在实验室规模的喷动流化床干燥器中,利用喷雾造粒技术对甲醇制烯烃催化剂进行了薄层成型实验研究,分析了料液浓度、料液流量、床层温度、喷嘴高度和过剩气体速度对催化剂薄层成型的影响,并对薄层催化剂进行了评价。实验结果表明,分层生长制备出的薄层催化剂,与原有催化剂相比,具有较好的催化性能和良好的流动性。     

甲醇制低碳烯烃催化剂研究新进展

对甲醇制低碳烯烃催化剂的最新研究进展进行了综述,详细介绍了ZSM-5分子筛催化剂和SAPO34分子筛催化剂的改性及其在MTP/MTO过程中的反应行为,并对MTO催化剂的发展趋势进行了分析.     

甲醇制烯烃反应机理研究进展

由于不同学者所采用催化剂和实验条件等的不同,对甲醇制烯烃(Methanol-to-olefin,MTO)反应机理的认识不尽相同,且存在一定的争议。本研究综述了近年来MTO反应机理研究的主要进展,目前较为认可的机理有卡宾机理、自由基机理、碳正离子机理和烃池机理等;介绍了MTO反应的影响因素以及前述不同反应机理的产生背景,并与相关文献数据结合,对各反应机理的合理性及其不足进行深入分析;基于文献中对催化剂表征及反应过程研究的相关结果,指出烃池机理能够更为合理地解释现有实验现象,表明烃池机理较其他几种反应机理具有更广泛的适用性。     

国内甲醇制烯烃技术进展

随着我国对低碳烯烃需求的不断增加,作为乙烯生产原料的石脑油、轻柴油等原料资源,也面临严重短缺的局面,甲醇制烯烃（MTO）技术的开发成功将有效缓解我国乙烯、丙烯等石油化工产业对宝贵的石油轻烃原料资源依赖程度,开辟出一个全新的烯烃生产工艺。     

甲醇制低碳烯烃ZSM-5基催化剂的研究进展

基于甲醇制低碳烯烃催化剂ZSM-5分子筛自身的结构和酸性问题,详细地介绍了当前ZSM-5分子筛改性的一些主要方法以及分子筛改性前后催化剂性能的变化,并阐述了该催化剂在甲醇制低碳烯烃工业中的应用情况,提出了甲醇制低碳烯烃催化剂目前存在的问题以及今后研究的方向。     

甲醇制烯烃催化剂再生动力学研究

反应过的甲醇制烯烃催化剂需要经过烧炭再生才能恢复活性,研究催化剂的再生动力学对控制催化剂再生过程的影响因素,恢复催化剂活性有重要意义。利用工业数据,在再生温度627~659℃,压力0.10 MPa(G)的条件下下,建立了反应速率-温度动力学方程以及V(CO)/V(CO_2)-温度动力学方程。将动力学研究应用到实际生产中,得到影响催化剂再生过程的主要控制因素,即再生温度和主风量。考察了再生温度和主风量对烟气中O2、CO和CO_2浓度的影响,结果表明:随着再生温度的升高,CO生成速率明显增加,CO_2生成速率明显减弱;随着主风量增加,再生温度有所提高,CO生成速率明显增加,CO_2生成速率略微增加。为了稳定烧焦过程必须控制再生温度和主风量,动力学研究为装置生产操作提供了指导。     

不同结构分子筛的甲醇制丙烯催化性能

在常压、空速为1.5 h^-1、反应温度为450℃条件下,考察了4种具有不同拓扑结构的分子筛(SAPO-34、ZSM-48、ZSM-5和beta)在甲醇转化制丙烯(MTP)反应中的催化性能,并对催化剂的积炭失活行为进行了研究。结果表明,从8元环到12元环,分子筛孔口尺寸越小,低碳烯烃(乙烯+丙烯)选择性越高,积炭失活速率也越快。孔道尺寸越大,丙烯/乙烯(P/E)比越高,但产物分布向C₄以上组分偏移,丙烯选择性降低。10元环分子筛具有较高的丙烯选择性,但催化剂的积炭失活速率随孔道体系的不同有很大差异。一维直通孔道的ZSM-48容易积炭失活,而具有三维交叉孔结构的ZSM-5表现出了优异的抗积炭失活性能。不同结构分子筛在MTP反应中催化性能的差异主要归因于分子筛的过渡态择形和产物择形作用的不同。     

Cu-Zn-Al-Li催化生物质合成气合成甲醇

在模拟生物质合成气气氛(CO/H2/CO2/N2=22/47/27/4, 体积比)下对Cu-Zn催化生物质合成气合成甲醇进行活性评价,发现Cu-Zn催化剂合成甲醇活性随反应时间单调下降,40 h后Cu-Zn催化剂活性比初始活性下降15%,添加Al能提高Cu-Zn催化剂的稳定性,添加Al后的Cu-Zn-Al及Cu-Zn-Al-Li催化剂40 h内合成甲醇的活性均未见明显下降. SEM和XRD表征研究发现,添加Li助剂有助于分散Cu活性组分,从而提高催化剂活性. 不同压力、空速及气体成分下,CO转化率均远高于CO2转化率,CO是生物质合成气合成甲醇的主要C来源.     

C207和C301甲醇催化剂精制气高氢还原浅析

介绍C207和C301甲醇催化剂的还原经验和使用情况。应用精制气高氢还原,催化剂具有起始还原温度低、出水集中在低温段、还原时间短、易操作等特点。还原后的催化剂活性好,使用寿命长,1炉催化剂可使用3年左右。     

环氧丙烷、二氧化碳和甲醇催化合成碳酸二甲酯

在KI／γ-Al2O3催化剂基础上．制备了负载型固体碱催化剂并对其催化环氧丙烷(P0),CO2和甲醇直接合成碳酸二甲酯(DMC)反应的活性进行了评价,发现K2O／4A分子筛的活性最好,碳酸二甲醇的收率达18．4％,高于现有文献值。实验表明,产物DMC是由PO和CO2生成的碳酸丙烯醇(PC)与甲醇进行醇交换所生成的,甲醇对PO和CO2合成PC反应具有助催化作用。     

Methanol Decomposition to Synthesis Gas Over Supported Pd Catalysts Prepared from Hydrotalcite Precursors

Supported Pd catalysts were prepared by solid-phase crystallization (spc) starting from MgAl hydrotalcite anionic clay minerals as the precursors, and were tested for the methanol decomposition to synthesis gas. The precursors based on [Mg₆Al₂(OH)₁₆CO₃ ^2-] · 4H₂O were prepared by coprecipitation from raw materials containing Pd²⁺, Mg²⁺ and Al³⁺ ions as the components of hydrotalcite. The precursors were thermally decomposed and reduced to afford supported Pd catalysts on MgAl mixed oxide. Pd-supported catalysts as a reference were also prepared by the impregnation (imp) method. The spc-Pd catalysts thus prepared afforded highly dispersed Pd metal particles and showed higher activity as well as lower activation energy than the imp-Pd catalysts. When the precursor was prepared under mild conditions, finer particles of Pd metal were formed over the catalyst, resulting in a high activity. In the case of spc-Pd catalysts, carbon monoxide adsorbed on Pd easily desorbed, compared with imp-Pd catalysts. It is likely that the high activity is due to the highly dispersed and stable Pd metal particles and the easy desorption of carbon monoxide.     

Effects of Aromatics on the Stability and Product Distribution of the Methanol to Olefin Process

Methanol to olefin process was investigated over a steam‐treated Ca‐ZSM‐5 catalyst in a flow‐type fixed bed reactor by adding aromatics to the methanol feed. As a comparison, the catalytic performance in the presence of nitrogen and water was also investigated. The experimental results exhibit that in the presence of aromatics, the total light olefin selectivity and the ethylene selectivity increased, while propylene selectivity increased with adding o‐xylene and m‐xylene to the methanol feed, but decreased with adding benzene, toluene, p‐xylene and ethylbenzen to the methanol feed. The catalyst was characterized by temperature‐programmed desorption of ammonia, N₂ adsorption, and scanning electron microscope. The adsorption of water and aromatics on the catalyst was also studied. Based on the results, it is concluded that aromatics may be responsible for the formation of light olefins and be more favorable for ethylene than propylene in methanol conversion.     

甲醇制低碳烯烃的原理和技术进展

从中国对烯烃的市场需求和前景出发,介绍了甲醇制烯烃的原理、催化剂和工艺的开发进展,比较甲醇制烯烃与传统的石油化工制烯烃的产物分布和收率,并进行了不同工艺生产低碳烯烃的技术经济分析,指出在中国开展煤基甲醇生产烯烃具有广阔的发展空间。     

Methanol decomposition to synthesis gas over supported Pd catalysts prepared from synthetic anionic clays

Supported Pd or Rh catalysts were prepared by the solid-phase crystallization method starting from hydrotalcite anionic clay minerals based on [Mg₆Al₂(OH)₁₆CO ₂ ²⁻ ]·4H₂O as the precursors. The precursors were prepared by a coprecipitation method from the raw materials containing Pd²⁺ and various trivalent metal ions which can replace each site of Mg²⁺ and Al³⁺ in the hydrotalcite. Rh³⁺ was also used for preparing the catalyst as comparison. The precursors were then thermally decomposed and reduced to form supported Pd or Rh catalysts and used for the methanol decomposition to synthesis gas. Among the precursors tested, use of Mg–Cr hydrotalcite containing Pd²⁺ resulted in the formation of efficient Pd supported catalysts for the production of synthesis gas by selective decomposition of methanol at low temperature. Although Pd²⁺ cannot well replace the Mg²⁺ site in the hydrotalcite, the Pd supported catalyst (Pd/Mg–Cr) prepared by the solid-phase crystallization method formed highly dispersed Pd metal particles and showed much higher activity than that prepared by the conventional impregnation method. When the precursor was prepared under mild conditions, more fine particles of Pd metal were formed over the catalyst, resulting in high activity. It is likely that the high activity may be due to the highly dispersed and stable Pd metal particles assisted by the role of Cr as the co-catalyst. This revised version was published online in November 2006 with corrections to the Cover Date.     

Deactivation of Copper Metal Catalysts for Methanol Decomposition, Methanol Steam Reforming and Methanol Synthesis

Laboratory and industrial results are reviewed to elucidate the general features of the deactivation of supported copper metal catalysts in various reactions involving methanol as reactant or product. Most catalyst types are based on Cu/ZnO formulations that contain stabilisers and promoters such as alumina, alkaline earth oxides and other oxides. These additional materials have several roles, including the inhibition of sintering and absorption of catalyst poisons. All copper catalysts are susceptible to thermal sintering via a surface migration process, and this is markedly accelerated by the presence of even traces of chloride. Care must be taken, therefore, to eliminate halides from copper catalysts during manufacture, and from reactants during use. Operating temperatures must be restricted, usually to below 300°C.In methanol synthesis involving modern promoted Cu/ZnO/Al₂ O₃ catalysts neither poisoning nor coking is normally a significant source of deactivation; thermal sintering is the main cause of deactivation. In contrast, catalyst poisoning and coking have been observed in methanol decomposition and methanol steam reforming reactions.     

甲醇水蒸气重整制氢催化剂性能的研究

研究共沉淀法制备Cu/Al2O3甲醇水蒸气重整制氢催化剂，考察催化剂组成和焙烧温度对催化剂性能的影响。结果表明当Cu质量分数为30．9％，焙烧温度为500℃时，催化剂性能最佳。并采用X射线衍射（XRD），程序升温还原（TPR）和热重分析等方法对催化剂表面性质进行探讨。