焙烧温度对甲烷部分氧化反应Ni/SiC催化剂催化行为的影响

考察了不同焙烧温度下的Ni/SiC催化剂在甲烷部分氧化反应中的催化行为。反应结果表明,700℃下焙烧的催化剂具有稳定的高活性,而900℃下焙烧的催化剂活性下降很快。提高焙烧温度可以增强活性组分与载体的相互作用,同时也容易使催化剂活性组份颗粒变大。900℃下焙烧的催化剂在反应中容易积炭,而且积炭的形貌与低温下焙烧的催化剂不同。     

Modeling of Coke Formation and Catalyst Deactivation in Propane Dehydrogenation Over a Commercial Pt-Sn/γ-Al2O3 Catalyst

Propane dehydrogenation was carried over a commercial Pt-Sn/γ-Al₂O₃ catalyst at atmospheric pressure and reaction temperatures of 580, 600, and 620°C and WHSV of 11 h^?1 in an experimental tubular quartz reactor. Propane conversions were measured for catalyst time on stream of up to nine days. The amounts of coke deposited on the catalyst were measured after one, three, six, and nine days on stream using a thermogravimetric differential thermal analyzer (TG-DTA) for each reaction temperature. The coke formation kinetics was successfully described by a coke formation model based on a monolayer-multilayer mechanism. In addition, catalyst deactivation was presented by a time-dependant deactivation function. The kinetic order for monolayer coke formation was found to be two, which would support a coke formation step involving two active sites. The kinetic order for multilayer coke formation was found to be zero. The activation energy for monolayer coke formation was found to be 29.1 kJ/mol, which was lower than the activation energy of about 265.1 kJ/mol for multilayer coke formation indicating that the presence of metals can promote coke formation on the catalyst surface.     

异丙苯裂化催化剂ASTRA-MB1积炭失活机理

通常催化剂的积炭失活由两种情况引起：活性位被覆盖和孔被堵塞。在热重分析仪上以异丙苯裂化反应为模型反应，采用CCAP（恒碳Arrhenius关系图）技术探讨了裂化催化剂SATRA-MB1的积炭失活机理，得到了反应速率常数和有效扩散系数随积炭量的变化规律。结果表明，当反应温度低于573K时，也的堵塞对催化剂的活性影响较大，当反应温度高于623K时，积炭主要发生在催化剂的外表面，其上的活性位被覆盖是造成催化剂失活的主要原因。理论上，通过降低催化剂粒径以增加其外表面的活性位数目，是提高催化剂利用率的有效途径。     

苯与丙烯烷基化反应中温度对Y沸石催化剂失活的影响

研究了丙烯与苯反应中反应温度对改性Y沸石催化剂失活的影响。通过TG、元素分析、FT-IR和裂解-色质等手段,分析了失活催化剂中的"焦炭"。结果表明,在较低反应温度下,催化剂失活的原因可能是由于沸石孔口直径为0 7～0 8nm,在超笼内生成较大分子的产物或中间化合物很难扩散出去,滞留在超笼中,导致孔口堵塞;在较高反应温度下,催化剂失活原因可能是催化剂活性中心缓慢地被积碳占据,直至积碳堵塞孔口后,活性便迅速下降。     

异丙苯合成失活FX-01催化剂的烧炭再生

以用于异丙苯合成的中试失活ＦＸ－０１催化剂为研究对象，研究了失活催化剂上积炭的性质及在不同温度下的烧炭再生情况，考察了再生前后催化剂的酸性、活性、晶相、比表面及孔结构等性能变化。结果表明，催化剂失活的原因在于炭沉积在孔的内表面上，从而占据了酸性中心；催化剂上的积炭在燃烧过程中会逐步石墨化，在５００℃以下难于将炭全部烧出。同时表明，经４５０℃烧炭再生后，可使积炭烧出９０％以上，催化剂表面积亦可恢复９０％，催化剂的活性基本得到恢复。     

催化柴油加氢裂化催化剂积炭形态及成因探讨

采用小型固定床加氢装置和Ni Mo型加氢裂化催化剂进行催化裂化柴油(LCO)加氢裂化反应,采用TG MS、GC MS、13C NMR和元素分析手段研究了催化剂积炭的类型和组成,并探讨了积炭的形成原因。结果表明,根据积炭燃烧的难易程度,催化剂积炭分为3种类型。积炭为缩合程度较高的稠环芳烃,侧链较少,且以短侧链为主。积炭中难溶性积炭较多,可溶性积炭主要为芘及其同系物和晕苯及其同系物,并含有少量氮杂环化合物。积炭前身物主要为芳烃,而LCO中芳烃含量过高以及较高的反应温度、低的氢分压是LCO加氢裂化过程催化剂积炭形成的主要原因。     

Comparative analysis of catalyst operation in the process of higher paraffins dehydrogenation at different technological modes using mathematical model

Abstract

This paper presents the results of comparative analysis of three run cycles of platinum catalyst for higher paraffins C₉–C₁₄ dehydrogenation process, performed using mathematical model. The results of model calculations were compared with the experimental data obtained at the industrial unit. It was established that deactivation of the platinum dehydrogenation catalyst is influenced by the technological modes of its operation, such as temperature, pressure, hydrogen/feedstock molar ratio and water supply. In the process of higher paraffins dehydrogenation, the phenomenon of platinum catalyst self-regeneration is observed. This occurs due to the action of feedstock components, in particular water and hydrogen involved in oxidation and hydrogenation of intermediate condensation products (coke structures). Model calculations showed that with a decrease in the hydrogen/feedstock molar ratio and simultaneous increase in water supply, depending on the temperature and composition of feedstock, it is possible to slow down deactivation process and increase the catalyst service life. This fact was experimentally confirmed at industrial unit.     

Characteristics of Coke Deposition Over a SAPO-34 Catalyst in the Methanol-to-Olefins Reaction

The deactivation of SAPO-34 catalyst in the methanol-to-olefins process has been studied at temperatures of 400 to 475°C. The catalyst activity keeps stable before a rapid deactivation occurs at a critical coke content. The analysis of retained coke species showed that methylbenzenes were the most abundant species at lower temperatures (400°C and 425°C), while polycyclic aromatics became the dominant species at 475°C. The growth in the retained coke species with increasing temperature comes from the enhanced reactivity of methylbenzenes and methylnaphthalenes at high reaction temperature, where methylnaphthalenes may function as another active reaction centers.     

The Modeling of Kinetics and Catalyst Deactivation in Propane Dehydrogenation Over Pt-Sn/γ-Al2O3 in Presence of Water as an Oxygenated Additive

A reduction in catalyst's activity with time-on-stream and the formation of side products are two of the problems associated with catalytic propane dehydrogenation (PDH). Previous studies have indicated that the presence of small amounts of oxygenated additives such as water can reduce coke formation and enhance catalyst activity. The aim of the present work was to develop an appropriate kinetic model for PDH over a commercial Pt–Sn/γ-Al₂O₃ catalyst in the presence of small amounts of water. Experimental data were obtained from a previous study where catalytic PDH was carried out in a bench scale reactor system at atmospheric pressure in the temperature range of 575–620°C in the presence of different amounts of water. The kinetics of the main dehydrogenation reaction were described in terms of a Langmuir-Hinshelwood rate expression and the effects of water on coke deposition and catalyst sintering were considered in a catalyst deactivation model to explain the observed optimum level in the amount of added water.     

甲醇制丙烯反应催化剂积炭行为的原位漫反射红外光谱研究

基于催化剂固体表面吸附态物种产生不同红外信号的机理,借助原位漫反射傅里叶变换红外光谱研究甲醇制丙烯（MTP）反应催化剂在不同操作条件下的积炭行为,分别考察了54种不同性质的ZSM-5催化剂在不同反应温度的甲醇制丙烯（MTP)反应中的积炭历程。实验结果表明,随着反应温度的升高或反应时间的延长,催化剂上积炭组分中多环芳烃等重组分比例均提高。磷改性或水热处理使催化剂的孔道结构、酸性位点及其分布发生改变,从而使催化剂上积炭物质的种类增多,多环芳烃等重组分比例升高。相同操作条件下,催化剂强酸位的酸强度越高,其积炭量越大,并在反应后期积炭速率相对较快。     

固定床渣油加氢处理装置催化剂积炭分析与表征

利用扫描电镜（SEM）、程序升温氧化（TPO-MS）、CHO元素分析仪等手段,对固定床渣油加氢处理装置催化剂上的积炭进行分析与表征。结果表明,沿着物料方向,渣油加氢催化剂上的积炭量呈先减少后增加的趋势,积炭的H/C原子比逐渐降低,芳香性越来越强,氧化温度逐渐增高。积炭的生成和油品中的氮化物存在着一定关系,含氮原子的沥青质更容易吸附在催化剂酸性点上并形成焦炭。     

THE INFLUENCE OF NATURE OF COKE ON KINETICS OF CATALYST REGENERATION

ABSTRACT

Experiments have been carried out to study the effects of coke composition on combustion parameters and burn-off time in the regeneration of coke-deactivated supported alumina catalyst. At high temperatures, results showed that the combustion behaviour is dependent on coke type as oxidizable and reduceable coke profiles versus time showed different trends. The curves of coke burn-off profiles were found to depend on the initial amount of coke deposited and on the oxygen concentration in the regenerating gas mixture. The higher the oxygen concentration, the shorter the time it takes to burn the same amount of coke. The high temperature combustion was assumed to follow the unreacted core model on the basis of which a model relating various parameters in coke deactivation was derived and the various dependencies demonstrated graphically for the different coke types. Oxidizable coke data fitted the linear model equation adequately while reducible coke data did not—another evidence of the difference in the kinetics of removal. Results further show a direct proportionality relationship between amount of coke accumulated under the same conditions and amount removed, confirming that the type of coke deposited is a function of accumulation conditions.     

MIP-DCR工艺技术的开发与应用

基于催化裂化反应化学,探讨降低干气和焦炭产率的催化裂化新技术（MIP-DCR）开发的原理;采用小型实验装置对该技术的可能操作模式进行探索;在中国石化九江分公司对该技术进行了工业应用,并采用CFD软件探讨了MIP-DCR工业试验装置的预提升混合器冷、热催化剂的可能混合方式。小型实验结果表明,在高活性、低剂油比的操作模式下干气和焦炭产率较低;工业应用结果表明：采用MIP-DCR技术通过减少热裂化和质子化裂化反应可以分别降低干气和焦炭15.48%和4.10%,增加液化气和汽油产率,同时降低能耗;MIP-DCR工艺打破热平衡限制,使剂油比成为独立变量,具有更多、更灵活的操作模式。     

THE INFLUENCE OF NATURE OF COKE ON KINETICS OF CATALYST REGENERATION

Experiments have been carried out to study the effects of coke composition on combustion parameters and burn-off time in the regeneration of coke-deactivated supported alumina catalyst. At high temperatures, results showed that the combustion behaviour is dependent on coke type as oxidizable and reduceable coke profiles versus time showed different trends. The curves of coke burn-off profiles were found to depend on the initial amount of coke deposited and on the oxygen concentration in the regenerating gas mixture. The higher the oxygen concentration, the shorter the time it takes to burn the same amount of coke. The high temperature combustion was assumed to follow the unreacted core model on the basis of which a model relating various parameters in coke deactivation was derived and the various dependencies demonstrated graphically for the different coke types. Oxidizable coke data fitted the linear model equation adequately while reducible coke data did not—another evidence of the difference in the kinetics of removal. Results further show a direct proportionality relationship between amount of coke accumulated under the same conditions and amount removed, confirming that the type of coke deposited is a function of accumulation conditions.     

溶剂萃取恢复渣油加氢转化催化剂活性的研究

催化加氢处理是渣油裂化加工的重要技术，但焦炭和金属在催化剂上的沉积将降低催化剂的活性。采用溶剂萃取法除去工业失活催化剂上沉积的焦炭和金属的研究结果表明，用四氢呋喃、吡啶和喹啉这3种含杂原子的有机强溶剂常温萃取催化剂，其去除焦炭能力很弱，而且会因这些溶剂的强吸附作用污染催化剂；盐酸洗涤能有效去除催化剂表面的钙、铁沉积层，但不能去除焦炭；低芳香性的加氢瓦斯油在400 C、H2压力为10MPa、反应1h的条件下可部分去除催化剂上的焦炭，但不具备强的氢化焦炭作用；1,2,3,4-四氢化萘因具有供给原子氢的能力，可以有效地氢化和去除催化剂上的焦炭。一旦除去一定量的焦炭或金属化合物沉积物，失活催化剂的加氢脱硫活性将得到恢复。     

焦化蜡油催化裂化反应过程生焦特性

 利用催化裂化工业平衡催化剂RGD-1,在提升管催化裂化中试装置和小型固定流化床实验装置上研究了大庆焦化蜡油催化裂化反应过程的生焦特性。采用吡啶红外法表征了积炭催化剂的表面酸性质,并对所生成焦炭的种类进行了分析。结果表明,在与直馏蜡油相同积炭率的条件下,焦化蜡油积炭催化剂的活性损失更大。焦化蜡油催化裂化反应生成的焦炭由吸附焦C_ad、脱氢缩合焦C_dh和氢转移焦C_ht构成。C_ad由碱性氮化物在L酸中心化学吸附所形成,是导致催化剂活性大幅度下降的主要原因,在催化裂化加工焦化蜡油过程中,必须牺牲部分催化剂的L酸中心以供C_ad沉积。常规反应条件下的焦炭组成中,在催化裂化加工焦化蜡油过程中,必须牺牲部分催化剂的L酸中心以供C_ad沉积。常规反应条件下的焦炭组成中,C_ad的质量分数约占20%;C_dh是焦炭的主要来源,质量分数占总生焦量的60%左右;氢转移焦C_ht的生成量受二次反应进行的程度影响很大,适当提高反应温度、缩短反应时间能够抑制氢转移反应的进行,减少C_ht的生成量,有利于降低焦炭选择性。     

Thermodynamic stability of coke-generating compounds formed on the surface of platinum dehydrogenation catalysts in their oxidation with water

Results of thermodynamic analysis and mathematical simulation of the deactivation of a platinum dehydrogenation catalyst by coke-generating compounds are presented. An approach to increasing the catalyst on-stream time has been proposed, suggesting implementation of a procedure for calculating the optimal flow rate of water fed to the reactor to maintain the conditions of thermodynamic equilibrium of the coke formation reaction and oxidation of intermediate condensation products with water.     

逐点程序升温氧化技术及其在积炭沸石催化剂烧炭中的应用

对逐点取样分析烧炭尾气组成的程序升温氧化技术进行了探讨，并将其应用于积炭沸石催化剂的恒温和程序升温氧化烧炭与通常的连续的程序升温氧化比较，本法可由一次试验同时获取烧炭速率、Ｈ／Ｃ比、积炭量等较全面的数据，准确判断烧炭起止温度（时间），避免通常方法因色谱基线飘移所引起误差。推导了求取烧炭速率等数据的简单计算公式。按烧炭温度和Ｈ／Ｃ比将积炭初步划分为低温、中温、高温炭三种。     

焦化蜡油催化裂化性能的研究

研究了纯焦化蜡油在ZCM-7催化剂上的催化裂化性能和产率分布，重点考察了不同碱氮含量和不同反应温度对纯焦化蜡油催化裂化反应的影响。这一研究结果将为更好地掺炼焦化蜡油作FCC原料提供重要的参考数据。     

汽提条件对两段提升管催化裂化待生剂汽提过程的影响

在模拟汽提实验装置上,对两段提升管催化裂化工业装置不同提升管内的待生剂进行了汽提实验研究。结果表明,汽提温度和汽提蒸汽流量均存在最佳值。当汽提温度为510℃时,两种待生剂的汽提效率达到最大值。继续提高汽提温度,一段待生剂汽提的产物分布和焦炭组成无明显变化;而二段待生剂的焦炭产率略有增加,且焦炭由可溶性焦炭向不可溶焦炭转变。汽提蒸汽的流量对两种待生剂汽提过程的影响趋势相似,但是二段待生剂达到最大汽提效率所需的蒸汽流量高于一段待生剂。汽提后待生剂的可溶性焦炭分析表明,二段待生剂可溶性焦炭的缩合度高于一段待生剂,且二段待生剂表面和孔道内沉积的可溶性焦炭的组成差别较小。