甲醇制烯烃反应过程中SAPO-34催化剂积炭动力学研究

在固定床反应器中研究了甲醇制烯烃反应过程中SAPO-34分子筛催化剂的积炭动力学，分别得到了催化剂积炭量与反应温度、剂醇比的经验关联式。结果表明，催化剂床层存在明显的积炭分布，在450 ℃，甲醇WHSV为15 h－1，催化剂积炭量随催化剂反应运行时间（Time on Stream, TOS）为25 min时，床层入口处的积炭量平均为9.56%，而出口处的积炭量平均为3.20%，属于平行失活，积炭主要来源于甲醇生成的高碳中间体，这些中间体在生成低碳烃的同时生成积炭。从积炭的生成机理出发，得到了SAPO-34分子筛催化剂的积炭动力学机理模型，将催化剂积炭量与一定催化剂停留时间内反应过程中甲醇的转化量相关联，该模型形式同样简单，能够较好地拟合实验数据。     

辽河渣油热转化和加氢裂化过程中生焦行为的研究

考察了辽河渣油热转化和浆液床催化加氢反应过程中生焦行为。研究生焦趋势与渣油物理化学组成的关系，初期生焦机制及其对后生焦的影响，并用高倍显微镜、傅立叶变换红外光谱技术对所生焦进行表征，结果发现，随加工苛刻度的增加，反应体系中生成的焦油细分散向簇状分散过渡、实姓焦对后期生焦有一定促进作用，在低压热转化过程中更为显著，生焦趋势不仅与反应条件有关而且与渣油物理化学性质相关，还与反应物系对生焦先躯物的胶溶能     

渣油加氢转化催化剂初期结焦规律的研究

以孤岛减压渣油及其超临界流体萃取分馏所得的窄馏分为原料,采用齐鲁石化公司胜利炼油厂VRDS装置的主催化剂,在高压釜反应器内考察了渣油加氢转化催化剂的初期结焦规律。结果表明,焦炭的生成是一个动态过程,其产率和性质与反应体系的温度、时间、氢气初始压力及原料的性质密切相关;结焦催化剂的孔壁焦炭沉积和堵孔现象严重,导致其比表面积大大减小,孔分布向小孔范围迁移。     

催化裂化生焦反应集总动力学模型的研究

催化裂化生焦反应集总动力学模型的研究任杰（抚顺石油学院石油化工系，抚顺１１３００１）关键词催化裂化，生焦，集总动力学，动力学模型在催化裂化反应过程中，催化剂因结焦而迅速失活．催化剂结焦量对催化剂再生和装置的热平衡影响很大，因此建立生焦动力学模型对指导...     

碳质颗粒添加物对渣油热反应生焦的影响

在高压反应釜中研究了三种不同碳质颗粒添加物对克拉玛依常压渣油420℃氮气气氛下热反应生焦的影响。实验结果表明，反应初期碳质颗粒在一定程度上抑制渣油的热反应生焦。碳质颗粒抑制生焦的能力与其表面对极性组分的润湿吸附能力有直接关系，表面易被极性组分润湿的颗粒吸附沥青质的能力强，其抑制渣油生焦的能力也强。碳质颗粒对沥青质的吸附能力和抑制生焦的能力与其比表面积没有直接关系。生焦量随反应时间的变化表明，碳质颗粒在生焦的初期有抑制生焦的作用，后期有促进作用。对甲苯不溶物（TI）的扫描电子显微镜（SEM）和热重（TG）分析表明，和不含添加物的TI相比，含添加物的TI中，小球状甲苯不溶物的数量少、直径小。沥青质和生焦前驱相在碳质颗粒添加物表面的吸附和铺展作用是抑制渣油生焦的主要原因，该作用可以限制生焦前驱相的融并长大，在反应的初始阶段减少生焦量。     

Large Zeolite H‐ZSM‐5 Crystals as Models for the Methanol‐to‐Hydrocarbons Process: Bridging the Gap between Single‐Particle Examination and Bulk Catalyst Analysis

The catalytic, deactivation, and regeneration characteristics of large coffin‐shaped H‐ZSM‐5 crystals were investigated during the methanol‐to‐hydrocarbons (MTH) reaction at 350 and 500 °C. Online gas‐phase effluent analysis and examination of retained material thereof were used to explore the bulk properties of large coffin‐shaped zeolite H‐ZSM‐5 crystals in a fixed‐bed reactor to introduce them as model catalysts for the MTH reaction. These findings were related to observations made at the individual particle level by using polarization‐dependent UV‐visible microspectroscopy and mass spectrometric techniques after reaction in an in situ microspectroscopy reaction cell. Excellent agreement between the spectroscopic measurements and the analysis of hydrocarbon deposits by means of retained hydrocarbon analysis and time‐of‐flight secondary‐ion mass spectrometry of spent catalyst materials was observed. The obtained data reveal a shift towards more condensed coke deposits on the outer zeolite surface at higher reaction temperatures. Zeolites in the fixed‐bed reactor setup underwent more coke deposition than those reacted in the in situ microspectroscopy reaction cell. Regeneration studies of the large zeolite crystals were performed by oxidation in O₂/inert gas mixtures at 550 °C. UV‐visible microspectroscopic measurements using the oligomerization of styrene derivatives as probe reaction indicated that the fraction of strong acid sites decreased during regeneration. This change was accompanied by a slight decrease in the initial conversion obtained after regeneration. H‐ZSM‐5 deactivated more rapidly at higher reaction temperature.     

Studies on accelerated deactivation of ruthenium-promoted alumina-supported alkalized cobalt Fischer-Tropsch synthesis catalyst

Accelerated deactivation of ruthenium-promoted alumina-supported alkalized cobalt (K-Ru-Co/γ-Al 2 O 3 ) Fischer-Tropsch (FT) synthesis catalyst along the catalytic bed over 120 h of time-on-stream (TOS) was investigated. Catalytic bed was divided into three parts and structural changes of the spent catalysts collected from each catalytic bed after FT synthesis were studied using different techniques. Rapid deactivation was observed during the reaction due to high reaction temperature and low feed flow rates. The physico-chemical properties of the catalyst charged in the Bed #1 of the reactor did not change significantly. Interaction of cobalt with alumina and the formation of CoAl 2 O 4 increased along the catalytic bed. Reducibility percentage decreased by 4.5%, 7.5% and 12.9% for the catalysts in the Beds #1, #2 and #3, respectively. Dispersion decreased by 8.8%, 14.4% and 26.6% for the catalysts in the Beds #1, #2 and #3, respectively. Particle diameter increased by 0.6%, 2.4% and 10.4% for the catalysts in the Beds #1, #2 and #3, respectively, suggesting higher rate of sintering at the last catalytic bed. The amount of coke at the last catalytic bed was significantly higher than those of Beds #1 and #2.     

Ni-Sm_x/SiC催化剂甲烷二氧化碳重整性能研究

用浸渍法制备了不同钐含量的Ni-Sm_x/SiC催化剂,其中,镍的质量分数为9%,氧化钐的质量分数分别为0、2%、3%、4%、5%、7%。采用常压微型固定床反应器考察了不同催化剂在甲烷二氧化碳重整反应中的催化性能,并用BET、ICP、XRD、H2-TPR、TG-DTA、XPS和TEM等技术对反应前后催化剂进行表征。结果表明,加入钐后,重整反应中甲烷和二氧化碳转化率明显提高。当钐含量为5%时,Ni-Sm5/SiC表现出最好的活性和稳定性,而且反应后催化剂表面积炭量最少。其原因是钐的加入提高了活性组分与载体的相互作用,有效减少了表面积炭、提高了催化剂的稳定性。     

程序升温条件下甲醇转化反应及流化床催化剂SAPO-34的积碳

在流化床反应条件下进行了SAPO-34催化的甲醇转化的程序升温反应,并分析了不同反应温度阶段的积碳产物.结合对反应流出物的检测结果和热分析及色质联用分析确定的积碳物种变化,解释了程序升温反应过程中甲醇转化特殊的变化趋势.在程序升温甲醇转化的积碳产物中,除芳烃外,还有一种饱和的多环烷烃积碳物种,它的生成影响了烃池活性中心的形成并引起甲醇转化在低温反应阶段的失活.甲基取代苯和甲基取代金刚烷是低温条件下SAPO-34催化的甲醇转化产生的主要积碳产物,它们在升温过程中会向甲基取代萘以及稠环芳烃转变.积碳物种的演变对应了甲醇转化在起始反应阶段(300～325oC)的反应活性升高和此后(325～350oC)的失活以及在更高温度阶段(350～400oC)活性的恢复.在反应性能评价和积碳分析基础上,首次提出了一种与金刚烷类积碳物种生成相关的低温甲醇转化的失活机理.     

The influence of La2O3 and TiO2 on NiO/MgO/α-Al2O3

Summary The effect of La₂O₃ and TiO₂ on product selectivity, methane conversion and coke formation over NiO/MgO/ α -Al₂O₃ catalyst were studied in a simultaneous steam and CO₂ reforming of methane to syngas. La₂O₃ and TiO₂ were added to the catalyst via incipient wetness impregnation and bulk precipitation techniques and catalyst activity was tested in a fixed bed quartz reactor. Results reveal that although the addition of these oxides has no effect on the product selectivity and methane conversion, but can reduce coke formation on the surface of the catalysts as it can enhance the mobility of lattice oxygen anions. The results further show that the catalysts prepared by bulk precipitation technique decrease the coke formation more effectively.     

生物质与石油焦共气化特性的研究

在内径为50mm,高约950mm的固定床反应器上对生物质与石油焦共气化特性进行了研究。研究了气化模式、石油焦添加比例、添加方式、粒径大小及气化温度对气化效果及焦油量的影响。结果表明,石油焦可以起到催化裂解生物质焦油的作用。随着氧气的体积分数从2%增加到15%时,气体的热值从5.35MJ/m³降低到2.98MJ/m³。在气化温度为700℃时,四种氧气含量下生物质单独气化时焦油产率平均值为6.4%,气体热值为4.31MJ/m³;生物质和石油焦混合气化时焦油产率平均值为2.9%,气体热值为5.19MJ/m³。石油焦的最佳添加比例为1∶1。生物质和石油焦不混掺焦油的产率最大,混掺其次,石油焦提前加入效果最好。随着添加石油焦粒径的增大,石油焦对生物质气化焦油的裂解率逐渐降低。在两种气化模式下,随着气化温度的升高,焦油的产率均逐渐降低。     

正交实验研究硝酸改性对活性焦表面性质及脱硫性能的影响

用硝酸对活性焦进行改性,采用正交实验法,考察了硝酸浓度、活化温度、活化时间以及煅烧温度对活性焦脱硫性质的影响,并在固定床反应装置上进行了活性焦评价实验。利用酸碱滴定、碘值测定、N₂吸附法、傅里叶红外光谱分析等对改性活性焦的表面酸碱性、比表面积、孔容等进行了分析和表征。实验结果表明,硝酸改性增加了活性焦的比表面积,提高了活性焦表面碱性;煅烧有助于提高表面碱性;硝酸改性明显提高了活性焦的脱硫性能。     

粒径对煤在H2/Ar等离子体中热解的影响

对粒径在H2／Ar等离子体煤热解制乙炔中的影响进行了研究，得到了煤的粒径与煤的裂解程度（转化率）、乙炔收率、乙炔在产品气体中摩尔分数和反应器壁结焦的关系，并且在考虑各种因素的制约下，对如何选择最佳粒径和粒径分布的问题进行了讨论。根据煤等离子体热解制乙炔反应器壁结焦的机理和煤粒径是影响反应器内结焦的重要因素，提出了进料粒径双峰分布缓解煤等离子体热解制乙炔装置结焦的新方法，实验证明该方法可行。     

等离子体甲烷偶联体系中纯氢气放电消除积炭

发现了等离子条件下甲烷偶联反应中形成的积炭可以通过该体系中纯氢气放电而消除.将消除积炭使用直流电场的正高压和负高压与使用交流电场作了比较，发现直流电场中无论使用正高压还是负高压，只有阴极上的积炭可以被消除，而交流电场中两极积炭均可被消除，反应器壁上的积炭在以上任何情况下均可被消除.基于实验事实提出了机理假设.消除积炭的量与输入功率、反应器对电极的直径比以及电极材料有关.     

Fischer-Tropsch Reaction Kinetics of Cobalt Catalyst in Supercritical Phase

Fischer-Tropsch synthesis under supercritical phase condition was examined in a continuous and a high-pressure fixed bed reactor by employing a cobalt catalyst (Co-R.Ru/γ-Al2O3). An integral reactor model involving Fischer-Tropsch reaction kinetics in the supercritical fluid n-hexane was used to describe the overall performance. On the basis of Langmuir-Hinshelwood-Hougen-Watson (LHHW) model, the reaction rate constants were obtained for the rate equations of CO conversion to CH4 formation under supercritical conditions.     

Unsteady state behavior of CO oxidation over a supported Pt catalyst in the millibar range

The alkylation of naphthalene with isopropanol was investigated over a HY (Si/Al=4) zeolite under the following conditions: flow reactor, liquid phase with decalin as solvent, 623 K, 40 bar. Despite complete filling of the zeolite pores by coke during the first hour of reaction, the rate of formation of isopropylnaphthalene remained very high. This is due to the development of a new reaction process involving transalkylation between the polyisopropyl naphthalenes entrapped in the pores and naphthalene followed by the realkylation of the former compounds with isopropanol.     

Kinetic of Regeneration of Coked Alumina by Thermogravimetry

Thermogravimetry is used for regeneration of the alumina catalyst which was deactivated by coke, formed in the transformation of 1,3-butadiene in a fixed bed continuous flow reactor. The Vyazovkin model-free kinetic analysis has been applied to data on thermal oxidation of carbonaceous deposits on the catalyst. This analysis has allowed us to estimate the activation energy (E) as a function of α (conversion) and to predict the time required to remove coke at a given temperature. This revised version was published online in July 2006 with corrections to the Cover Date.     

Direct Non‐Oxidative Methane Conversion in a Millisecond Catalytic Wall Reactor

Direct non‐oxidative methane conversion (DNMC) has been recognized as a single‐step technology that directly converts methane into olefins and higher hydrocarbons. High reaction temperature and low catalyst durability, resulting from the endothermic reaction and coke deposition, are two main challenges. We show that a millisecond catalytic wall reactor enables stable methane conversion, C₂₊ selectivity, coke yield, and long‐term durability. These effects originate from initiation of the DNMC on a reactor wall and maintenance of the reaction by gas‐phase chemistry within the reactor compartment. The results obtained under various temperatures and gas flow rates form a basis for optimizing the process towards lighter C₂ or heavier aromatic products. A process simulation was done by Aspen Plus to understand the practical implications of this reactor in DNMC. High carbon and thermal efficiencies and low cost of the reactor materials are realized, indicating the technoeconomic viability of this DNMC technology.     

Magnetic resonance imaging of flow-distributed oscillations

The formation of stationary concentration patterns in a packed-bed reactor (PBR), using a manganese-catalyzed Belousov-Zhabotinsky (BZ) reaction in a mixed sulfuric-phosphoric acid medium, was studied using magnetic resonance imaging (MRI). The PBR was composed of a column filled with glass beads, which was fed by a continuous stirred tank reactor (CSTR). As the reactor is optically opaque, investigation of the three-dimensional (3D) structure of these reaction-diffusion-advection waves is not possible using conventional image capture techniques. MRI has been used to probe this system and the formation, 3D structure, and development of these waves has been studied. At reactor startup, traveling waves were observed. After this initial period the waves stabilized and became stationary. Once fixed, they were found to be remarkably stable. There was significant heterogeneity of the reaction fronts, which were not flat, as would be expected from a plug-flow reactor. Instead, the reaction wave fronts were observed to be conical in shape due to the local hydrodynamics of the bed and specifically the higher velocities and therefore lower residence times close to the wall of the reactor.     

Model-free kinetics applied to regeneration of coked alumina

Thermogravimetry is proposed to study the alumina catalyst regeneration deactivated by coke, after being used in the transformation of styrene in a fixed bed continuous flow reactor. The model-free kinetic approach has been applied to data for the thermal oxidation of carbonaceous deposits on the catalyst. The activation energy (E) was calculated as a function of a (conversion) and T (temperature), by using Vyazovkin model-free kinetic method, allowing to estimate time required to remove coke at a given temperature. This revised version was published online in August 2006 with corrections to the Cover Date.