甲烷化催化剂失活原因浅析

简要介绍对该公司年产8万t合成氨装置净化工段甲烷化工序使用的J105型甲烷化催化剂快速失活的原因进行了分析,判断是由于进气中含有硫醇和噻吩硫化物引起的,采取的措施是将原用的T102精脱硫剂更换为EAC-6硫醇精脱硫剂。     

耐硫甲烷化催化剂研究进展

耐硫甲烷化作为一种非传统路径的甲烷化技术,目前尚未在煤制气领域有成熟的工业应用。介绍Mo系耐硫甲烷化催化剂的研究状况,主要针对负载型耐硫甲烷化催化剂的活性组分Mo、载体及助剂对催化剂甲烷化活性的影响以及对催化剂研究状况进行总结分析,并展望耐硫甲烷化技术未来发展方向。     

QDB-03型耐硫变换催化剂失活的原因分析

结合QDB-03型耐硫变换催化剂的使用情况和废催化剂/过滤剂的分析数据,对该催化剂失活的原因进行分析,初步判定催化剂活性快速衰退的原因。     

国内外城市煤气耐硫甲烷化催化剂研究概况

耐硫甲烷化催化剂的开发引起了城市煤气甲烷化工艺的改革,简化了流程,节省了资源和投资。本文介绍了这方面的研究发展情况。     

SDM-1型耐硫甲烷化催化剂宏观动力学

<正> 1 引言 耐硫甲烷化催化剂具有耐硫、抗析炭等特点,可简化甲烷化工艺流程,便于工厂操作。设计合理的工业反应器和延长催化剂使用寿命是目前工业化急需解决的问题。作者对SDM-1型耐硫甲烷化催化剂宏观动力学进行了研究。 2 实验 2.1 测试装置 实验流程见图1。反应器为增压内循环无梯度反应器,将直径27mm、高25mm的催化剂筐置于导流环中,筐下方装有调速叶轮,转速1200～7200r/min。用热电偶测量反应床温度。实验用原料气由钢瓶中配制,配制后倒置48h以上,使气体充分混合。原料气经净化器脱除有害杂质后,由质量流量计计量,进入预热器升温至300℃,送反应器,出口气体经分离器至皂膜流量计计量,然后放空,或送HP5890色谱仪分析。 动力学测试前通过空白试验证实实验装置无催化活性。当转速为2850r/min,实验范围内消除了外扩散影响。H_2S体积浓度控制在0.09％     

一种高活性耐硫甲烷化催化剂的反应性能

本文报道了一种多组分钼系耐硫甲烷化催化剂的反应性能。考察了反应温度、压力、空速和原料气组成对活性的影响,结果表明,此催化剂具有活性高、稳定性好和对原料气中硫浓度适应性强等特点。在压力2.0MPa、空速1000h~(-1)、入口温度380℃的反应条件下,CO 转化率约达95％,甲烷选择性约为75％。CO 转化率与原料气中 H_2S 浓度呈X_(co)∞[H_2S]~(0.05)关系。     

耐硫变换催化剂失活原因分析及解决措施

针对某合成氨企业净化车间变换系统催化剂频繁出现失活现象,造成经济损失并影响到生产装置稳定运行的情况,对可能导致变换催化剂失活的原因进行了分析,确定了催化剂中毒是由原料煤中的有机氯含量高引起的,同时提出了源头控制、过程管理及终端治理的应对措施。     

甲烷化催化剂及其失活研究进展

阐述甲烷化催化剂活性组分、载体和助剂种类对催化性能的影响。分析催化剂失活的主要原因为中毒失活、积炭失活和烧结失活。目前在国内外工业装置上得到应用的主要为Al2O3、镁铝尖晶石类负载的Ni基甲烷化催化剂。通过载体改性、助剂添加及调配提升催化剂性能是催化剂研发的主要方向。复合载体可以形成特定的稳定结构,提高催化剂的热稳定性;其较高的比表面积利于Ni的分散;碱金属、碱土金属和稀土金属的添加,可以调变载体表面酸性和电负性,减小Ni晶粒尺寸,降低积炭的可能性。     

煤制合成天然气甲烷化催化剂工业运行与失活原因分析

对煤制合成天然气甲烷化催化剂工业应用全生命周期进行了研究,总结了煤制合成天然气甲烷化催化剂在不同应用时期内的运行特征;采用硫/碳分析仪、XRD、氮气物理吸脱附等表征手段,对失活催化剂进行检测,分析了不同装填位置催化剂硫中毒、积碳及高温烧结情况;通过不同状态催化剂的活性评价实验,验证了硫、积碳、烧结对催化剂活性的影响程度;并讨论了引起工业催化剂床层热点位置下移直至完全失活的原因。研究结果表明:轻度积碳对催化剂活性影响不大,严重积碳会造成催化剂粉碎,床层压降升高;高温烧结会造成催化剂比表面积显著下降,热点位置下移,但不足以使催化剂失活;硫在催化剂上的吸附达到一定值后会向下穿透,硫对催化剂的低温活性影响显著,对催化剂的高温活性影响较弱,硫在催化剂上的缓慢积累是催化剂失活的主要原因。     

Hydrothermal synthesis of sulfur-resistant MoS2 catalyst for methanation reaction

The flower-like MoS₂ with high activity for sulfur-resistant methanation reaction was prepared by hydrothermal method. S/Mo mole ratios in feed and sulfidation condition during preparation were studied. The results show that higher S/Mo mole ratio increases the activity. Sulfidation in 3% H₂S/H₂ results in structure with longer and more ordered multi-layered MoS₂ which increases the activity and stability.     

Oxidized K2CO3/MoS2 as a novel sulfur-resistant catalyst for Fischer-Tropsch reaction

Potassium-promoted MoS₂ is an active catalyst for mixed alcohol synthesis from CO and H₂. When K₂CO₃/MoS₂ is oxidized, however, it produces mostly hydrocarbons, of which 40–50 wt% are C₂–C₄ alkanes. The reaction rates also substantially increase. Since oxidized K₂CO₃/MoS₂ can tolerate a high level (up to 300 ppm) of H₂S in the CO-H₂ feed, it could serve as a novel sulfur-resistant Fischer-Tropsch catalyst.     

低温耐硫甲烷化催化剂硫化过程

采用燃烧法制备MoO₃/ZrO₂催化剂,该催化剂由于具有比表面积大、粒径小的优点,表现出很高的低温耐硫甲烷化活性。通过考察硫化工艺条件的影响发现,硫化过程中硫化时间、硫化压力、硫化氢浓度的影响不大,而硫化温度的影响较明显,300℃下恒温硫化效果最佳,表征结果表明,300℃下恒温硫化可以使催化剂完全硫化,得到较多的MoS₂晶格条纹,有利于提高催化剂的甲烷化活性。恒温硫化时,硫化温度低于300℃时,催化剂硫化不完全,形成的MoS₂晶格条纹较少;硫化温度过高会导致催化剂过度硫化并发生团聚,从而导致催化剂的耐硫甲烷化活性降低。分步硫化时目标温度为400℃时效果最佳,且与300℃恒温硫化的效果接近,对于MoO₃/ZrO₂催化剂,可选择300℃恒温硫化,适宜的硫化条件为：硫化压力0.1 MPa,硫化温度300℃,硫化氢浓度3% H₂S/H₂,硫化时间4 h。     

制备方法对钼基耐硫甲烷化催化剂性能的影响

合成气甲烷化是煤制天然气工艺的主要过程之一。与传统的镍基催化剂相比,钼基催化剂用于耐硫甲烷化可以省去精脱硫过程和水汽变换过程,具有一定的技术和成本优势。但是钼基催化剂活性相对较低,尤其是低温活性和高温稳定性有待提高。对比研究不同方法制备的MoO₃/ZrO₂催化剂在固定床反应器上的耐硫甲烷化性能,发现采用溶液燃烧法制备的催化剂在相同条件下具有较高的耐硫甲烷化活性,当空速为5000 h^-1、反应压力为3MPa、反应温度为300℃和400℃时其CO转化率可分别达到26%和79%。催化剂的N₂物理吸附、透射电镜、X射线衍射和Raman光谱等表征结果表明,溶液燃烧法制备的催化剂具有较小的ZrO₂晶粒尺寸和较大的比表面积,活性组分Mo物种在ZrO₂载体上的分散性更好。而采用共沉淀法和浸渍法制得的MoO₃/ZrO₂催化剂存在不同程度的Mo物种团聚现象,导致其耐硫甲烷化活性较低。     

Cerium-promoted Ni/SiO2 catalyst for CO methanation

Ce-promoted Ni catalysts were developed and applied in a CO methanation reaction. The 10%Ni/SiO₂ catalyst exhibits poor initial CO conversion (32.8%) and rapid deactivation with the highest methane selectivity during CO the methanation reaction. In contrast, the 4%Ce–10%Ni/SiO₂ catalyst shows dramatically increased initial CO conversion, which is up to 90.7%. Additionally, the apparent activation energy, Ea value, of 4%Ce–10%Ni/SiO₂ was calculated to be 102.2 kJ/mol according to the Arrhenius equation, which is much lower than that of the 10%Ni/SiO₂ catalyst, which was 139.1 kJ/mol. Based on various characterization results, it is found that the added Ce significantly improves the dispersion of the supported nickel, suppresses the sintering of nickel particles, and forms more adsorbed CO species of three-fold carbonyl species, resulting in higher CO conversion and good stability during the CO methanation reaction.     

Precursor effect on catalytic properties of Mo-based catalyst for sulfur-resistant methanation

The catalytic activity of Mo-based catalysts prepared from (NH₄)₆Mo₇O₂₄ and (NH₄)₂MoS₄ was compared in the sulfur resistant methanation process. The catalyst using oxide precursor had relatively higher activity than the catalyst using sulfide precursor, and the presulfidation procedure almost had no effect on the catalytic performance of the catalyst using oxide precursor. In view of the characterization results, it could be supposed that the amorphous MoS₂ was more active for sulfur-resistant methanation than the crystalline MoS₂. The molybdenum sulfides and oxides with lower valence states (Mo⁴⁺, Mo⁵⁺) could be responsible for the catalytic activity and make a possible contribution to the carbon monoxide methanation in the reaction condition.     

ZrO2添加对MoO3/Al2O3催化剂耐硫甲烷化性能的影响

采用共沉淀法制备了ZrO₂-Al₂O₃复合载体,并进一步制备了MoO₃/ZrO₂-Al₂O₃催化剂,考察了不同ZrO₂质量分数对催化剂结构及其耐硫甲烷化性能的影响。利用N₂物理吸附、X射线衍射、H₂程序升温还原和透射电子显微镜等手段对催化剂的结构进行了表征。结果表明,MoO₃/ZrO₂-Al₂O₃中ZrO₂的添加可以明显削弱MoO₃与载体间的相互作用,促进Mo物种的还原,适量ZrO₂的存在还有助于提高催化剂的比表面积,改善Mo活性相的分散性,使催化剂表现出优异的耐硫甲烷化活性。     

Effect of boron addition on the MoO_3/CeO_2–Al_2O_3 catalyst in the sulfur-resistant methanation

The effect of boron on the performance of MoO_3/CeO_2–Al_2O_3 catalysts, which were prepared with impregnation method, was investigated. The catalysts were characterized with N_2 adsorption–desorption, XRD, H_2-TPR, and NH_3-TPD, and were tested in sulfur-resistant methanation. The results indicated that the MoO_3/CeO_2–Al_2O_3 catalysts modified by boron showed higher catalytic performance in sulfur-resistant methanation. The CO conversion increased from 47% to 62% with 0.5 wt% boron content. When the content of boron was under 0.5 wt%, the results suggested there was an increase in the amorphous form of MoO_3 caused by the generation of weak and intermediate acid sites, which had weakened the interaction between the active components and supports. While, the catalyst added 2.0 wt% boron showed the strong acid sites and the largest crystalline size resulting in the uneven distribution of ceria.     

Effect of a promoter on the methanation activity of a Mo-based sulfur-resistant catalyst

The effect of adding Co, Ni or La on the methanation activity of a Mo-based sulfur-resistant catalyst was investigated. As promoters, Co, Ni and La all improved the methanation activity of a 15% MoO₃/Al₂O₃ catalyst but to different extents. Similar improvements were also found when Co, Ni or La was added to a 15% MoO₃/25%-CeO₂-Al₂O₃ catalyst. The promotion effects of Co and Ni were better than that of La. However, the catalytic methanation activity deteriorated the most with time for the Ni-promoted catalyst. The used catalysts were analyzed by nitrogen adsorption measurement, X-ray diffraction and X-ray photoelectron spectroscopy.