Sulfur Adsorption and Poisoning of Metallic Catalysts

The catalytic activity of most transition metals is drastically reduced by the presence of hydrogen sulfide or other sulfur-containing compounds at extremely low concentration in the reagents. This poisoning effect is a major problem in many catalytic reactions, especially hydrogen reaction such as methanation of coal synthesis gas or reforming of naphthas. On the other hand, beneficial effects on the selectivity can be obtained by a partial and well-controlled poisoning of catalysts by sulfur. For example, an enhancement of the selectivity for heavier hydrocarbons in the CO + H₂ reaction has been reported [1-3]. Increases of the selectivity for partial hydrogenation of diolefins to the corresponding monoolefins were also observed [4, 5]. In the catalytic reforming of naphthas, partial poisoning by sulfur minimizes excessive hydrocracking.     

载金属离子的介孔炭对噻吩吸附性能的研究

采用模板法制备了介孔炭,并利用浸渍法将金属离子Ni^2＋、Co^2＋负载在该介孔材料上。研究了不同吸附剂、温度和浓度对吸附的影响。结果表明,介孔炭负载Ni^2＋或Co^2＋比13X负载Ni^2＋脱硫效果好,Ni^2＋／介孔炭比Co^2＋／介孔炭脱硫效果好。当负载Ni^2＋的量为10％,温度为20℃时,介孔炭的脱硫效果最好。     

Influence of Sulfur Poisoning on CO Adsorption on Pd(100)

Investigations of CO adsorption on sulfur covered Pd(100) surface were conducted in order to obtain insight into the deleterious effects of sulfur on this system. First-principles density functional theory calculations indicate that CO is markedly destabilized when it shares surface atoms with neighboring sulfur. Based on the analysis of the electronic properties, the decrease in binding is attributed to localized S?CPd bonding plus the interaction between CO and S. The internal C?CO stretching frequency was blue shifted relative to that on the clean surface as a result of the weakening of the C?CPd bonds. The poisoning effect is predicted to diminish for distant sites. Kinetic Monte Carlo simulations (with adsorbate lateral interactions included) revealed that the introduction of S creates competition for adsorption sites. At a finite temperature, CO adsorption is essentially nullified when the surface is covered by a quarter of monolayer of sulfur in agreement with experiments. Aside from reduction of possible adsorption sites, sulfur severely inhibits the mobility of CO as well.     

Influence of Potassium Doping on the Activity and the Sulfur Poisoning Resistance of Soot Oxidation Catalysts

Soot oxidation on potassium nitrate impregnated cerium oxide and manganese cerium mixed oxide was investigated using TG-FTIR. It was found, that potassium nitrate promotes the soot oxidation by enhancing the contact between the soot and the catalyst, as soot ignition temperature corresponds to the melting point of potassium nitrate for both the individual and the mixed oxide. Since potassium nitrate is easier sulfatized than cerium or manganese, the susceptibility of the catalyst to sulfur poisoning is considerably decreased.     

金属基整体式催化剂的研究进展

系统地介绍了金属基整体式催化剂的结构、制备、性能及其数值模拟方面的研究进展,阐述了该类催化剂在工业催化领域中的应用。通过对研究现状的分析,提出了金属基整体式催化剂的制备仍需进一步解决的几个关键问题,指出金属基整体式催化剂在吸/放热反应耦合过程中的应用极具发展潜力。     

The Oxidation of Methane at Low Temperatures Over Zirconia-Supported Pd,Ir and Pt Catalysts and Deactivation by Sulfur Poisoning

Abstract  

The oxidation of methane over zirconia-supported Pd, Ir, and Pt catalysts at low temperatures under an oxidizing atmosphere and the effect of SO₂ on this reaction were investigated. An Ir–Pt/ZrO₂ catalyst exhibited high activity and low deactivation by SO₂. Characterization of the catalyst indicated the presence of a highly oxidized Pt species that was stabilized by the addition of Ir.     

Study on the Poisoning Mechanism of Sulfur Dioxide for Perovskite La0.9Sr0.1CoO3 Model Catalysts

The reaction and poisoning mechanism of SO₂ with La_0.9Sr_0.1CoO₃ model catalysts have been investigated. The structure and the chemical states of the model catalysts have been studied by using AES, XPS and XRD techniques. The results indicated that SO₂ diffused into the La_0.9Sr_0.1CoO₃ film during poisoning. La₂(SO₄)₃ species was formed on the surface of the film and La₂(SO₄)₃, La₂(SO₃)₃, La₂O₂SO₄ and CoO species were found in the interior. The perovskite structure of La_0.9Sr_0.1CoO₃ was destroyed by invasion of SO₂. The concentration of sulfur in the film layer was related to the reaction temperature and time. After the sample was poisoned for a fairly long time, the distribution of sulfur in the La_0.9Sr_0.1CoO₃ layer became homogeneous, suggesting that a dynamic equilibrium was achieved between the poisoning reaction and the decomposition of the sulfates. XRD and catalytic activity test results proved that the destruction of perovskite structure and the formation of sulfates were the main causes of deactivation.     

FCC催化剂的镍中毒

本文总结了关于流化催化裂化（FCC）催化剂上镍沉积方式、形态和镍沉积对催化裂化反应影响的研究成果。分析了镍中毒引起催化剂失活的原因,对当前FCC加工过程中防止镍中毒的方法进行了总结和比较,并对今后国内FCC催化剂镍中毒研究课题提出建议。     

氨厂催化剂的氯中毒及其预防(续)

本文概述了氨厂催化剂的氯中毒及其相关机制和防范措施,分析了氯的来源,指出预防氨厂催化剂氯中毒的最有效方法是使用脱氯剂。     

壳聚糖与凹凸棒土对金属离子吸附作用研究

研究了壳聚糖的提取、天然凹凸棒土的改性方法以及壳聚糖和改性凹凸棒土对Cu^2＋、Pb^2＋、Cd^2＋、Zn^2＋等金属离子的吸附作用。结果表明：壳聚糖和改性凹凸棒土的混合使用有利于降低成本,提高吸附效率。     

钛促进型耐硫变换催化剂QCS-04的性能及工业应用

钛促进型耐硫变换催化剂由于具有变换活性高,硫化性能好和抗水合能力强等优点,在我国的大、中型化肥厂及城市煤气厂的耐硫变换装置上得到广泛应用。本文介绍了钛促进型QCS－04耐硫变换催化剂性能特点以及在几种不同典型流程中的工业应用情况,对其经济效益和推广应用前景进行了简单的讨论和分析。     

非均相金属钯配体催化剂的研究进展

Suzuki-Miyaura反应是一类具有工业化应用前景的C-C键合成反应。反应多数是在均相金属钯配体催化剂催化下完成。均相催化具有催化效率高、产品选择性好等优点,但催化剂回收困难,增加了反应成本,限制了其应用。非均相金属钯配体催化剂是将均相金属钯配体催化剂固载到载体上,使其在不影响反应活性和选择性的同时,实现循环使用,已成为Suzuki-Miyau-ra反应的研究热点。对几年来以有序介孔材料MCM-41和SBA-15、无机载体SiO2和Al2O3、聚苯乙烯和聚乙二醇等合成材料以及天然高分子材料为载体,制备非均相金属钯配体催化剂的方法及其催化性能进行了综述。     

Controlling the Sulfur Poisoning of Ag/Al2O3 Catalysts for the Hydrocarbon SCR Reaction by Using a Regenerable SOx Trap

The deactivation of a silver-based hydrocarbon selective catalytic reduction catalyst by SO_x and the subsequent regeneration under various operating conditions has been investigated. Using a sulfur trap based on a silica-supported catalyst it was found that, for a Ag/SiO₂ + Ag/Al₂O₃ combination, the negative effect of SO₂ on the n-octane-SCR reaction can be eliminated under normal operating conditions. The trap can be regenerated by hydrogen at low temperatures or at higher temperatures using a hydrocarbon reductant.     

苯加氢用铂催化剂硫中毒及其再生的研究

以硫化氢为硫源,考察硫对苯加氢用铂催化剂性能的影响及其再生性能。结果表明,对苯加氢反应而言,铂催化剂的活性随原料气中硫含量和运行时间的增加而呈下降趋势。因此,为使苯加氢反应长时间稳定运行,宜将其原料气中的硫控制在2.0×10-6(体积分数)以下,在1.0×10-6(体积分数)以下最佳。铂催化剂的硫中毒是可逆的,去除毒源后,其活性逐渐恢复至正常水平。     

六氟化硫中可水解氟化物的吸附试验及分析

通过理化分析和吸附试验分析并讨论了稀土硅铝复合氧化物在不同压力下对六氟化硫(SF6)气体中可丁水解氟化物的吸附能力,通过吸附能力的变化确定了最佳吸附效果的压力条件.结果表明:室温下稀土硅铝复合氧化物对SF6中可水解氟化物的最佳吸附压力约为1.10 MPa.     

硫改性镍催化剂丁烯-1双键临氢异构性能

将Ni/Al_2O_3催化剂浸渍于有机多硫化物(TPS-37)中制备得到硫改性Ni/Al_2O_3催化剂。采用X射线荧光光谱(XRF)、热重-质谱(TG-MS)联用、X射线光电子能谱仪(XPS)和程序升温还原(TPR)等方法对催化剂进行表征,并考察了硫改性Ni/Al_2O_3催化剂上丁烯-1双键临氢异构性能。结果表明,硫改性Ni/Al_2O_3催化剂经高温氢气活化及甲苯萃取后,催化剂上硫含量基本不变。硫与催化剂之间存在较强的相互作用,使氧化镍在相对较低的温度下被H2还原;硫改变了Ni金属周围电子环境,从而显著改善催化剂的双键临氢异构性能。在反应温度60℃,氢压1.6 MPa,氢气和碳四烃物质的量之比(氢烃比)为0.013的条件下,硫改性Ni/Al_2O_3催化剂催化丁烯-1双键临氢异构反应,丁烯-1转化率可达92.6%,丁烯-2选择性为97.5%。催化剂稳定性实验结果表明,硫改性催化剂催化性能好,稳定性优良。     

耐硫变换催化剂失活原因综述

自Ｃｏ－Ｍｏ系耐硫变换催化剂问世以来,人们对其制备工艺、反应机理、动力学等进行了常任主细致的研究。随充变换催化剂的广泛应用,催化剂失活的原因引起了人们的普遍关注。对国内外Ｃｏ－Ｍｏ纱耐硫变换催化剂失活的原因进行了综述。     

芳烃加氢金属催化剂抗硫性研究的进展

介绍了在油品芳烃加氢过程中提高镍金属和贵金属催化剂抗硫性研究的进展,对镍催化剂,添加碱金属、碱土金属和其他组分,调节镍金属的还原度及形成镍硼合金等有一定的效果;对贵金属催化剂,铂和钯形成合金,改变金属的颗粒度和载体的酸碱性能及添加碱金属等常被采用。     

分子筛催化噻吩类硫化物与烯烃烷基化脱硫研究

采用GC—FPD,GC—MS,NH3-TPD及BET等手段,以噻吩,2-甲基噻吩,3-甲基噻吩,2-乙基噻吩及2,5-二甲基噻吩为模型硫合物,异丁烯为烷基化剂,对HZSM-5,Hβ,HM,HY,HMCM-41等分子筛为催化剂催化噻吩类硫化物与异丁烯的烷基化反应进行了研究,并比较不同分子筛的酸强度分布及孔径大小对噻吩类硫化物与异丁烯的烷基化反应性能的影响。结果表明,Hβ,HM,HY,HMCM-41催化剂催化噻吩与异丁烯的烷基化反应在温和的反应条件下(如80℃,常压)即可达到较高的转化率,分子筛催化剂的孔径大小是影响催化括性的关键因素。