重整催化剂积碳失活研究进展

积碳是重整催化剂失活的重要原因,针对这一问题,综述了重整催化剂失活过程中,积碳在金属和载体的沉积情况,积碳前驱物在积碳形成中的作用,介绍了研究催化剂表面积碳形态及类型的表征手段,论述了影响重整催化剂积碳失活的因素。     

流化床中硝基苯加氢制苯胺的催化剂失活研究

利用加速失活的方法研究流化床中硝基苯气相加氢制备苯胺过程中的催化剂失活与积碳量的关系.催化剂的积碳量在6%以内时,催化剂的活性较高.但经过此突变点后,催化剂的活性大幅度下降.利用拉曼光谱及X射线衍射等方法测定了失活过程中的碳的形态.失活过程中催化剂上的积碳量增加且逐渐变为石墨态的碳,覆盖了催化剂的活性位,导致不可逆失活.该结果为工业装置的操作及确定再生周期等提供了依据.     

汽油氧化重整制氢反应催化剂失活因素研究

对汽油氧化重整制氢反应催化剂失活因素进行了理论分析与实验研究 ,研究结果表明 :在进行反应中 ,催化剂表面积碳是造成催化剂失活的原因 ,为避免催化剂表面积碳 ,反应的最小水碳比应大于理论计算的最小水碳比。计算了在不同反应温度条件下的最小理论水碳比     

Pt/SO_4~(2-)/ZrO_2-Al_2O_3催化正己烷异构化反应中的失活研究

制备了Pt/SO_4~(2-)/ZrO_2-Al_2O_3(Pt SZA)催化剂,考察了Pt SZA在正己烷异构化反应中的失活与再生问题,并通过XRD、Raman、TG、IR和TPO-MS等手段对失活前后催化剂的晶相、硫质量分数和积碳量进行表征。结果表明:在165℃反应550 min后,Pt SZA催化剂几乎完全失活。失活前后催化剂的晶相结构和硫质量分数没有明显变化,失活催化剂上仅有微量积碳生成,高温氢气和空气再生处理消除了失活催化剂上少量的积碳,催化活性得到完全恢复,催化剂上微量积碳的产生是催化剂失活的主要原因。     

催化剂的失活研究及其在使用中的改进建议

催化剂的活性直接影响着渣油加氢装置的运行周期。本文首先简单的分析了催化剂失活的原因、阶段,随后着重陈述了由于催化剂的金属沉积、积碳及操作条件的改变造成了催化剂的失活过程,最后还对催化剂在使用过程中提出了改进建议。     

基于强抗积碳的CO_2重整镍基催化剂的研究进展

针对甲烷-二氧化碳重整用Ni基催化剂易于高温积碳失活问题,系统总结了重整催化剂的抗积碳性能的影响因素,分析了载体的载氧性、表面酸碱性和载体孔道结构与抗积碳性之间的关系,探讨了助剂改性催化剂表面酸碱性、金属与载体相互作用和活性组分的分散度对抗积碳性的影响,揭示了特殊场物理技术改性的催化剂表面活性组分Ni粒子尺寸和分散度与催化剂抗积碳性之间的关联度,阐释了Ni基催化剂积碳的原因,提出了改善重整催化剂的抗积碳性的具体方法和措施,并展望了强抗积碳的重整催化剂的发展趋势。     

煤焦油加氢过程中NiWP/Al_2O_3催化剂失活研究

在固定床加氢微型反应器上进行NiWP/Al_2O_3催化剂的煤焦油模化物加氢实验,分析了催化剂初期快速失活的原因。本实验采用N_2吸附-脱附、XRD、元素分析、SEM、TPO-MS、TG、FTIR和XPS等方法分析催化剂反应前后的性质变化及表面积碳情况,结果表明:随着反应进行,催化剂的加氢脱硫活性和加氢脱氧活性变化不大,而加氢脱氮活性快速下降;催化剂快速失活的主要原因是表面生成积碳,覆盖其表面的反应活性中心,使加氢反应活性下降;表面积碳的主要成分是芳香烃,还有少量脂肪烃。     

铜基催化剂的失活再生研究进展

综述铜基催化剂的主要合成方法,对其重要的工业应用包含合成气制甲醇、甘油氢解和草酸二甲酯加氢反应,分析其具体失活原因多为烧结、中毒与积碳。针对烧结失活的主要措施为掺合杂原子、选择金属氧化物做载体及通过载体结构限制铜原子的迁移。而针对积碳与中毒的主要措施为减少毒性物质与催化剂的接触;根据积碳与毒性物质产生的条件与路径,消除积碳与毒性物质来源;失活催化剂再生处理。     

蜡油加氢装置催化剂运行分析及优化措施

中石化洛阳分公司220×10~4t/a蜡油加氢处理装置是油品升级重点项目。其中延长催化剂使用寿命是蜡油加氢装置现阶段运行的核心问题,催化剂活性直接影响到蜡油加氢装置的产品质量。影响催化剂活性的主要因素为催化剂的积碳和金属沉积,其中积碳失活可以通过催化剂的再生进行活性恢复,而金属沉积则造成催化剂永久失活。为保证蜡油加氢催化剂活性能保持到2019年大检修,需要对蜡油加氢的原料以及操作条件进行优化调整。     

Z417/Z418蒸汽转化催化剂的应用及积炭中毒失活原因分析

对中国石油西安石化分公司新建制氢装置蒸汽转化催化剂的使用进行了总结，剖析转化催化剂积炭和中毒失活的原因，提出了防止积炭和中毒失活的预防措施及保证装置长周期运行的方法。     

n-Dodecane reforming over nickel-based monolith catalysts: Deactivation and carbon deposition

The carbon deposition behavior of Ni-based monolith reforming catalysts was studied during n-dodecane autothermal reforming, partial oxidation, and steam reforming. One catalyst formulation was nickel deposited on cerium zirconium oxide (CZO) coated monolith, while the second formulation was nickel directly deposited on bare monolith. In both formulations, a series of catalysts with a range of nickel loadings (0–16 wt.%) were prepared to examine the influence of nickel loading on carbon deposition and to elucidate the benefits of the reducible oxide support CZO on carbon deposition. Carbon deposition was generally more pronounced at higher nickel loadings and on catalysts lacking CZO. Nickel supported on bare monolith suffered from excessive carbon deposition and carbon-induced monolith disintegration. The morphologies of carbon were determined by scanning electron microscopy (SEM). Temperature programmed oxidation (TPO) indicated the presence of two types of carbon. The low-temperature TPO peak can be attributed to coating carbon, while the high-temperature peak corresponds to filamentous carbon structures, including large whiskers and smaller filaments. Accumulation of whisker carbon had a deleterious effect on the monolith substrate resulting in the physical destruction of some samples. X-ray diffraction (XRD) gave no evidence for the presence of graphite or carbide species in carbon-deposited catalysts. The experimental results of this study are used to diagnose the causes for nickel catalyst deactivation during autothermal reforming and for proposing strategies to mitigate the deactivation.     

天然气蒸汽重整制氢技术研究现状

甲烷水蒸汽重整是目前广泛应用的制氢方法,具有工艺成熟、装置运行可靠、经济性强、环保和资源合理利用等优点,在适应大规模生产方面具有不可比拟的优势,但面临着工业设备投资大及催化剂易积炭失活的问题。国内外对甲烷水蒸汽重整的重点研究方向是制备高活性、高稳定性和强抗积炭性能的催化剂以及研制低水碳比条件下应用的催化剂,有效降低能耗。甲烷水蒸汽重整催化剂分为非贵金属催化剂、负载贵金属催化剂和过渡金属碳化物及氮化物催化剂,这些催化剂均能在高空速下使反应达到热力学平衡,甲烷转化率和CO/H2选择性均很高。金属活性组分负载量、载体、助剂及负载过程对催化剂活性、稳定性和选择性有重要的影响。同时,在甲烷水蒸汽重整反应过程中,催化剂活性组分的烧结、重新组合以及催化剂表面的积炭均可以引起催化剂失活,其中,催化剂表面积炭是最主要的影响因素,积炭反应是发生C—H和C—C键断裂后的表面碳聚反应,可引起活性中心中毒,堵塞孔道,甚至使催化剂粉化。积炭反应的影响因素包括添加稀土金属氧化物、催化剂制备工艺和催化剂的载体。     

Deactivation of a Ni-Based Reforming Catalyst During the Upgrading of the Producer Gas, from Simulated to Real Conditions

The deactivation of a nickel reforming catalyst during the upgrading of the producer gas obtained by gasification of lignocellulosic biomass was studied. The research involved several steps: the selective deactivation of the catalyst in a laboratory scale; the streaming of the catalyst with the producer gas of a downdraft and an oxygen/steam circulating fluidized bed (CFB) gasifier; and tests in a reformer placed in a slipstream of the CFB gasifier. The information obtained allowed to elucidate the catalyst deactivation mechanisms taking place during the reforming of the producer gas: physical deactivation by deposition of fine ashes, aerosol particulate or carbon; poisoning by H₂S and HCl present in the gas phase and thermal sintering because of the high operation temperatures required to avoid the chemical deactivation. These physical and chemical effects depended on the composition of the biomass fuel.     

CH4-CO2 reforming over Ni/Al2O3 aerogel catalysts in a fluidized bed reactor

Ni/Al₂O₃ aerogel catalysts were synthesized by a sol-gel method combined with a supercritical drying route. The catalytic performances of the catalysts in methane reforming with CO₂ were investigated in a quartz micro-reactor. The results indicated that the aerogel catalyst showed higher specific surface area and higher dispersivity of nickel species than those of impregnation catalyst. The excellent catalytic performances and stabilities were achieved over the aerogel catalysts in the fluidized bed reactor. Comprehensive characterization with TG, XRD and FESEM revealed that the aerogel catalyst in the fluidized bed had much lower carbon deposition than that in the fixed bed. The fluidization of the aerogel catalyst greatly improved the contact efficiency of gas-solid phase, which accelerated the gasification of the deposited carbon. In contrast, the deactivation of the aerogel catalyst was caused by the carbon deposition due to the catalyst without moving in the fixed bed. Moreover, decreasing activity of the impregnation catalyst in the fluidized bed resulted from the poor fluidization state of catalyst particles and low effective active sites on surface of catalyst.     

Changes in crushing strength of hydrocarbon steam-reforming catalyst along the reactor tube under operating conditions

The catalytic hydrocarbon steam reforming process for the production of synthesis gas is accomplished using a nickel-based catalyst. The catalyst is designed to suit fixed-bed continuous-flow tubular reactor operation. It is manufactured in cylindrical form and possesses a relatively high crushing strength. The nickel active ingredient is homogeneously dispersed on the carrier surface in its oxide form. The currently applied reformers are vertical continuous-flow reactors consisting of several hundred tubes in which the reactants—hydrocarbon and steam—are introduced at the top of the reactor tubes and the reformed gaseous products are collected at their bottom ends. Performance and long-term uninterrupted operation of hydrocarbon steam reformers are severely affected by the alteration of the crushing strength of catalyst pellets. Changes in the crushing strength of the catalyst along the reformer tube under actual operating conditions were investigated and the results are presented here. The usefulness of the crushing strength as a diagnostic test for catalysts is discussed. This test has direct bearing on the selection of prospective catalyst charge, the reuse of partially used catalyst charge, and the investigation of catalyst failures.     

A Multi‐Function Compact Micro‐Channel Reactor Coated with Sulphur Tolerant Catalyst for LPG Steam Reforming

Hydrogen fuelled polymer electrolyte fuel cells (PEFC) offer clear environmental benefits. Lack of viable hydrogen infrastructure in the near future means that a key issue is availability of hydrogen at the point of use. Liquefied petroleum gas (LPG) offers advantages as a fuel over other hydrocarbons because there is already an infrastructure in place for remote areas. Hydrogen supply via steam reforming of LPG is therefore a feasible avenue of achieving the environmental benefits. Commercial grade LPG unavoidably contain sulphur as an odorant, the sulphur needs to be removed from the fuel stream before it reaches the reformer catalyst and fuel cell. Utilizing sulphur tolerant catalysts in the reformer leads to a simpler fuel processor design. Thermal management and reforming efficiency has been a challenge for the sulphur tolerant catalysts. In this paper, a multi‐function compact micro‐channel reactor designed for hydrocarbon steam reforming was evaluated for use with LPG. A sulphur tolerant catalyst was wash‐coated on to the reforming layers. The reformer was tested over a wide range of reactor temperatures, steam to carbon ratios and fuel flow rates. Over 60% of H₂ composition can be achieved at high reforming temperatures with a LPG supply rate of 0.75 dm³ min⁻¹ (STP) and a S/C ratio of 4.     

一段炉催化剂析炭及炉管的超温保护

从原料气质量、系统负荷、水碳比等方面分析了一段炉催化剂析炭的原因;论述了一段炉转化管超温的影响因素;提出了炉管降温措施和处理方法,总结了实施效果;指出避免催化剂析炭是控制一段炉转化管超温的重要措施。     

Catalyst deactivation and engineering control for steam reforming of higher hydrocarbons in a novel membrane reformer

The catalyst deactivation and reformer performance in a novel circulating fluidized bed membrane reformer (CFBMR) for steam reforming of higher hydrocarbons are investigated using mathematical models. A catalyst deactivation model is developed based on a random carbon deposition mechanism over nickel reforming catalyst. The results show that the reformer has a strong tendency for carbon formation and catalyst deactivation at low steam to carbon feed ratios for high reaction temperatures and high pressures . The trend is similar for the cases without and with hydrogen selective membranes. Based on this preliminary investigation, an engineering control approach, i.e., in-site control with a concept of critical/minimum steam to carbon feed ratio, is proposed and used to determine the carbon deposition free regions for both cases without and with hydrogen membranes. The comparison between the reported data and model simulation shows that the critical steam to carbon feed ratio predicted by the model agrees well with the reported industrial/experimental operating data.     

Effect of Anode off‐gas Recycling on Reforming of Natural Gas for Solid Oxide Fuel Cell Systems

The effect of anode off‐gas recycling (AOGR) on the characteristic performance of a natural gas reformer equipped with a precious metal catalyst is investigated experimentally. The reformer is operated both with synthetic AOGR gas and in steam reforming (SR) conditions. The characteristic performance in SR and AOGR mode are compared with equilibrium, and it is found that equilibrium is more readily achieved in AOGR mode. The reformer is used for extended periods of time (100–1,000 h) in conditions where carbon formation is thermodynamically possible to measure any changes in characteristic performance. No significant change in the performance is observed due to carbon formation or catalyst deactivation. The reformer could be successfully implemented in a 10 kW SOFC system with an anode off‐gas recycling loop.     

Ethanol steam reforming over Co-based catalysts: Role of oxygen mobility

The effect of oxygen mobility on the bio-ethanol steam reforming of ZrO₂- and CeO₂-supported cobalt catalysts was investigated. The supported catalysts were prepared by incipient wetness impregnation (IWI) and characterized through N₂ physisorption, X-ray photoelectron spectroscopy, temperature programmed oxidation, laser Raman spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, O₂ pulse chemisorption, isotopic labeling, and transmission electron microscopy techniques at various life stages of the catalyst. The results indicated that the catalyst deactivation was due mostly to deposition of various types of carbon on the surface although cobalt sintering could also be contributing to the deactivation. The addition of ceria was found to improve the catalytic stability as well as activity, primarily due to the higher oxygen mobility of ceria.