哌啶对负载型Pt催化剂加氢脱硫性能的影响

将ZSM-5溶于偏硅酸钠水溶液,用水热合成法以十六烷基三甲基溴化铵作模板剂自组装合成了ZSM-5/MCM-41介孔硅铝分子筛(ZM)。以二苯并噻吩(DBT)和哌啶作为模型含硫和含氮化合物,考察了含氮化合物对ZM担载的Pt催化剂加氢脱硫(HDS)反应性能的影响。结果表明,DBT在Pt/ZM催化剂上主要通过直接脱硫(DDS)反应路径脱硫,引入哌啶显著抑制了DBT的HDS反应。与DDS相比,哌啶对加氢路径(HYD)抑制作用更强,并且几乎完全抑制了HYD路径含硫中间体的脱硫。动力学分析表明,DBT的HDS反应和DDS路径级数为一级而其HYD路径则为零级,说明DDS和HYD反应可能是在Pt/ZM不同活性中心上进行的。     

载体对Pd和Pt催化剂加氢脱硫反应性能的影响

以质量分数为0.8%的二苯并噻吩(DBT)的十氢萘溶液为模型化合物,考察了SiO_2,Si-MCM-41和Al-MCM-41负载的Pd和Pt催化剂加氢脱硫(HDs)反应性能,并与传统的γ-Al_2O_3负载的催化剂进行了对比.反应结果表明,负载型Pd和Pt催化剂在DBT的HDS反应中表现出不同的反应特点.Pd催化剂具有较高的加氢反应路径(HYD)选择性,而Pt催化剂则表现出较高的直接脱硫路径(DDS)选择性.载体结构和表面酸性显著影响其负载的Pd和Pt贵金属催化剂的HDS活性以及HYD选择性和稳定性.提高载体比表面积和酸性有利于提高负载型贵金属催化剂HYD选择性.Al-MCM-41具有规整的介孔结构、较高比表面积和较强酸性,其负载的Pd和Pt催化剂表现出较高的HYD选择性和稳定性.研究还发现,催化剂加氢裂化反应活性随载体酸性的提高而增加.     

CeO2改性的Ni2P催化剂加氢脱硫反应性能

以二苯并噻吩（DBT）的十氢萘溶液（DBT质量分数为0．8％）为模型化合物,考察了CeO2改性的Ni2P催化剂加氢脱硫（HDs）反应性能,并用X射线衍射（xRD）和程序升温还原（TPR）对催化剂进行了表征。XRD结果表明,CeO2的引入抑制了Ni5P4杂晶的生成,Ni2P催化剂的晶粒尺寸随CeO2含量的增加而降低。TPR结果显示,在CeO2与Ni2P催化剂前驱体之问存在较强的相互作用,虽然抑制了NiO的还原,但促进了Ni2P物种的生成。从DBT的HDS反应结果可以看出,CeO2对于Ni2P加氢脱硫催化剂是一种有效的助剂,它的引入同时促进了Ni2P催化剂直接脱硫（DDS）和加氢（HYD）路径反应活性,从而提高了催化剂HDS活性。其中,催化剂的HYD反应活性随CeO2含量的变化规律与催化剂晶粒尺寸变化规律相似,说明Ni2P催化剂HYD反应活性对催化剂结构变化较为敏感。     

柴油加氢脱硫反应路径影响机理研究进展

文章主要介绍了柴油馏分中难脱除的二苯并噻吩类（DBTs）硫化物存在的加氢脱硫反应路径,其中DDS和HYD是目前研究较多的主要反应路径。总结了催化剂活性助金属、硫化氢、氮化物以及氢分压对加氢脱硫反应路径选择性的影响并探究其影响机理。     

Si改性对NiMo/Al2O3催化剂加氢脱硫性能的影响

以中和法合成的不同SiO₂含量的改性氧化铝为载体,本文制备系列Si改性的NiMo/Al₂O₃催化剂,采用X射线衍射（XRD）、N₂物理吸附（BET）、程序升温脱附（NH₃-TPD）、吡啶吸附红外光谱（Py-IR）、程序升温还原（H₂-TPR）、高分辨透射电镜（HRTEM）和X射线光电子能谱（XPS）等分析手段进行详细表征。表征结果显示,引入Si减弱了活性金属与载体之间的相互作用,改善了催化剂的孔结构与表面酸性分布,提高了活性相分散度和金属硫化度,促使形成更多的II类NiMoS活性相。以二苯并噻吩（DBT）为模型化合物,在固定床加氢装置上考察了系列催化剂的加氢脱硫（HDS）性能,结果表明,引入Si可降低DBT的加氢反应活化能,提高反应速率常数,进而提高催化剂的加氢脱硫活性。对比DBT转化率在50%时的脱硫产物分布表明引入Si可影响催化剂的反应路径选择性,直接脱硫路径（DDS）选择性从83.69%增加至92.89%,证实了催化剂的表征规律。     

二苯并噻吩在Ni-Mo-W/γ-Al2O3上加氢脱硫机理的研究

研究了二苯并噻吩(DBT)在Ni-Mo-W/γ/Al2O3上的加氢脱硫(HDS)反应产物分布、可能的反应网络以及温度对产物分布的影响,揭示了HDS反应的可能机理.研究发现,DBT在Ni-Mo-W/γ-Al2O3上的HDS反应主要通过直接氢解路径和加氢路径进行,且后者的速率是前者的两倍.考察了芳烃(萘)、硫化物(硫化氢)和氮化物(喹啉)三种物质对DBT在Ni-Mo-W/γ-Al2O3催化剂上HDS反应的影响,结果表明,芳烃对反应有较弱的抑制作用,并且对两个路径的抑制作用相当.氮化物喹啉对反应有较强的抑制作用,其主要是通过竞争吸附作用抑制加氢路径.硫化物H2S对反应也有一定的抑制作用,其抑制直接氢解脱硫路径,但对加氢路径有一定的促进作用.     

贵金属硫化物催化剂的制备及其在催化加氢反应中的应用

贵金属硫化物催化剂对含硫化合物加氢、加氢脱硫、加氢脱氮和卤代硝基化合物加氢等方面有特殊应用,选择性高,不易失活.总结了国内外贵金属硫化物制备方法,综述了各类贵金属硫化物在催化加氢方面的应用,并对贵金属特别是Pd的不同种硫化物种间相互转变条件进行了探讨.     

碱性助剂对加氢脱硫催化剂性质及活性的影响

选择了一种碱性有机盐作为助剂合成加氢脱硫催化剂,通过N2吸附-脱附、XRD、CO_2-IR、NH_3-TPD、原位CO-IR和模型化合物加氢及FCC汽油脱硫反应,表征评价了碱性助剂对催化剂性质及反应活性的影响。通过对比发现了由于生成部分微孔导致含助剂催化剂的比表面积有所提高,孔容、孔径有所下降。由于助剂的加入使催化剂具有一定量的碱性吸附位,原位CO-IR表征证实含碱性有机盐助剂催化剂在硫化过程中会更多生成CoMoS相。通过模型化合物加氢反应和工业FCC汽油脱硫反应证实含碱性有机盐助剂催化剂具有一定的加氢异构能力,其在FCC汽油脱硫反应中的选择性更好,更适用于生产高辛烷值汽油。     

FCC汽油加氢脱硫反应过程及其催化剂研究进展

综述了国内外有关FCC汽油中硫的存在形态、HDS反应原理及其催化剂的研究进展.一般认为,FCC汽油中的硫化物形态主要为噻吩类化合物,且主要集中在重馏分中,汽油的HDS反应原理的研究也都集中在噻吩的加氢脱硫反应上.传统的HDS催化剂由于烯烃饱和率过高不适于FCC汽油的HDS,可通过改变催化剂的酸性来调整其HDS/HYD选...     

杂质对Ru/AC催化秸秆水解液加氢反应的抑制作用

采用Ru/AC催化主要成分为葡萄糖、木糖的秸秆水解液加氢,探究了水解液中各杂质对加氢反应性能的影响,通过N₂物理吸附、CO化学吸附、热重分析、场发射扫描电镜、热解气质联用等分析手段对反应后失活催化剂进行了系统表征。结果表明：水解液中可能存在的木质素、纤维素酶、无机盐、呋喃类衍生物、有机弱酸、芳香族化合物等杂质中,木质素和纤维素酶对加氢反应具有很强抑制作用,其余杂质仅在溶液中总杂质含量较高时才表现出明显的抑制作用;木质素和纤维素酶阻碍加氢反应的主要原因是其能够附着于催化剂上,堵塞催化剂孔道,并覆盖活性位,导致催化剂失活。     

氮化物对柴油加氢脱硫影响的研究进展

分别从催化剂,工艺条件等方面介绍了氮化物对柴油加氢脱硫反应(HDS)影响的机理。介绍了氮化物对柴油HDS反应影响的动力学研究。结果表明:氮化物对柴油HDS反应具有抑制作用;在不同催化剂活性中心上和不同的工艺条件下氮化物对柴油HDS反应的影响存在差异且符合于拟一级反应动力学。氮化物对柴油HDS的影响研究,可以指导高活性催化剂的开发,寻求最优柴油HDS反应工艺。     

Effect of nitrogen removal from light cycle oil on the hydrodesulphurization of dibenzothiophene, 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene

Five light cycle oil feeds (LCO) with nitrogen contents ranging from 744.9 to 16.5 mg/L were prepared by removing organic nitrogen compounds gradually through adsorption on a silica column. These feeds were hydrotreated over a commercial Ni-Mo/Al₂O₃ catalyst to study the effect of nitrogen compounds on the hydrodesulphurization (HDS) of dibenzothiophene, 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene. It was found that nitrogen compounds had the most negative impact on the HDS of 4- and/or 6-substituted dibenzothiophenes. The temperatures to achieve 50% HDS conversion were 5, 20 and 25 °C lower for dibenzothiophene, 4-methyldibenzothiphene and 4,6-dimethyldibenzothiophene, respectively, when the nitrogen content in the feed was reduced from 744.9 to 16.5 mg/L. Our results also revealed that, at lower temperatures, about 20% of the nitrogen compounds from the original light cycle oil were adsorbed on the catalyst's surface. The HDS of 4,6-dimethyldibenzothiophene was retarded until the HDN rate became greater than the adsorption rate, which might have freed some hydrogenation sites for adsorption. This phenomenon was not observed for the HDS of DBT. Our results suggest that nitrogen compounds and 4,6-dimethyldibenothiophene competed for the same type of active sites, and dibenzothiophene also could have been converted over a different site. In addition, the hydrodenitrogenation activity was also enhanced by the removal of nitrogen compounds. The experimental data was fitted to a Langmuir–Hinshelwood type of kinetic equation by assuming that the inhibition only affected the hydrogenation pathway.     

Thiophene conversion and ethanol oxidation on SiO2-supported 12-PMoV-mixed heteropoly compounds

Surface properties of supported MoV heteropoly compounds and their activities in hydrodesulfurization of thiophene and oxidation of ethanol were studied. Vanadium incorporated into the phosphomolybdic acid anion increased extent of oxidative dehydrogenation of ethanol to acetaldehyde, whereas the catalyst with (VO)²⁺ increased complete ethanol oxidation to CO₂. The catalysts with (VO)²⁺ or one V atom in the anion showed an increase in HDS activity. Vanadium in anion of phosphomolybdic acid also increased hydrogenation ability. Acidic sites of medium strength were proved to be the most suitable for ethanol oxidation. Such explicit dependence of thiophene hydrodesulfurization on any type of acidic sites was not confirmed. Activity order of supported MoV heteropoly compounds in HDS of thiophene correlated well with the amount of hydrogen consumed during TPR.     

H2和含硫化合物在MoS2边缘表面的吸附活化

对H₂和含硫化合物在MoS₂边缘表面的吸附活化及反应机理的理论研究结果进行了概述。重点描述了H₂在MoS₂表面的吸附、解离、硫覆盖度对H₂吸附解离的影响以及含硫化合物在MoS₂表面的吸附和反应。在原子水平上揭示了硫化钼催化剂上H₂的吸附解离机理和加氢脱硫反应机理。     

TiO2-SiO2复合氧化物的理化性质及其对柴油加氢精制性能的影响

采用溶胶-凝胶法结合CO₂超临界流体干燥技术制备了不同Ti/Si原子比的TiO₂-SiO₂复合氧化物（TS-n）,考察了Ti/Si原子比、焙烧温度对复合氧化物比表面积、孔结构、酸性及原子结合状态的影响,通过重油催化裂化柴油加氢精制反应考察了以TS-1、TS-4为载体的催化剂脱硫性能的差异.结果表明,TiO2经SiO2复合改性后,热稳定性和晶态稳定性大幅度提高;TiO₂-SiO₂复合氧化物的酸性及原子间的相互作用与Ti/Si原子比有直接的关系;载体的晶态组成及酸性和催化剂的酸性对催化剂的加氢脱硫性能有显著影响,复合氧化物中锐态型TiO₂的存在强化了载体与金属组分之间的相互作用,提高了催化剂的加氢脱硫活性,不同类型的酸性中心对柴油中不同类型的硫化物具有不同的脱除能力,Bronsted 酸中心较多的催化剂对结构简单的硫化物脱除能力强,Lewis酸中心较多的催化剂对结构复杂的硫化物有较好的脱除效果.     

Hydrotreating catalysts containing zeolites and related materials—mechanistic aspects related to deep desulfurization

The deep hydrodesulfurization (HDS) of diesel fuels requires the decomposition of refractory compounds such as 4,6-dimethyldibenzothiophene (46DMDBT). There is a general agreement on the fact that the low reactivity of these compounds is due to steric hindrance of the transition state leading to C–S bond cleavage, which annihilates the effect of the promoter to a large extent. The consequence is that their so-called “direct desulfurization pathway” is particularly inhibited.

Various issues were considered to circumvent the difficulty to eliminate the HDS-resistant molecules and therefore to reach deep desulfurization. Two of them at least consist in designing new hydrotreating catalysts (in addition to the improvement of the alumina-supported conventional catalysts): (i) catalysts with improved hydrogenation properties; (ii) bifunctional catalysts containing an acid component. The main findings obtained with the first class of catalysts are summarized. On these catalysts HDS was found very sensitive to the inhibition by aromatics. The studies regarding the second category of catalysts are analyzed in more detail. Several techniques were used to introduce acid components, including mesoporous materials, in hydrotreating catalysts: physical mixing, binding, deposition of sulfide precursors on an acid–alumina support, deposition of sulfide precursors on an acidic support. Most of these catalysts were found more active than conventional catalysts in the HDS of compounds such as 46DMDBT. The various interpretations of the effect of the acid component are reported and discussed. It is however generally accepted that the improvement of the reactivity, on this category of catalysts, of the HDS-resistant compounds is due to their acid-catalyzed isomerization and disproportionation into more reactive derivatives. When acidic materials were used directly as supports it was difficult to obtain a good association of, for instance, molybdenum, with promoters. Nevertheless, in certain cases catalysts were obtained which were more active than conventional catalysts in the HDS of compounds such as 46DMDBT or of gas oils containing such impurities. However although the catalysts containing acid components proved efficient in hydrotreating various kinds of oils, they suffer several drawbacks such as deactivation by coke deposition and inhibition of HDS by aromatics. Moreover nitrogen impurities which inhibit HDS even with conventional catalysts may also impede seriously their use in practice.     

Hydrotreating catalyst deactivation by coke from SRC-II oil

Samples of a CoMo/Al₂O₃ catalyst were partially deactivated with SRC-II feed in an autoclave reactor to give coked samples of 5 to 18 %C. The coked catalysts were analyzed for surface area, pore volume, coronene adsorption and diffusivity, and their catalytic activity determined for hydrodesulfurization (HDS), hydrodeoxygenation (HDO) and C-N hydrogenolysis (CNH) using model compounds. All of the above measurements decreased with increase in coke content. Property data indicate that some pores are blocked by coke and diffusivity results show narrowing of pore mouths with increasing coke content. Catalyst deactivation versus coke level was identical for HDS and HDO, but less for CNH. A simple model of coke deactivation was developed to relate activity to coke content. Coke is envisioned as forming wedge-like deposits in the catalyst pores.     

两种制备方法不同的钼镍催化剂加氢性能对比研究

利用微反装置,对采用相同原料、相同配比、不同方法制备的两种新型MoNi催化剂进行了加氢性能初步评价,对不同温度下的产物中的含硫化合物和芳烃及多环芳烃含量进行了分析,实验表明两种催化剂都具有很高的脱硫活性,但是脱硫性能和芳烃饱和性能却有很大的区别,并对两种催化剂加氢性能的差异进行了讨论。     

Effects of organic nitrogen compounds on hydrotreating and hydrocracking reactions

A major issue encountered in hydrotreating and hydrocracking reactions, as in many others fixed bed catalytic processes, is the decrease of catalytic activity with time on stream. The organic nitrogen compounds act as temporary poisons in hydroprocessing catalysts besides being coke precursors. The inhibiting effects of nitrogen compounds present in crude oil have been studied on SRGO hydrotreating reactions and VGO hydrocracking reactions. The results show that selective removal of nitrogen by adsorption using silica and alumina in varying proportions, would not only increase the HDS catalyst activity by more than 60%, but would also reduce hydrogen consumption. This step of nitrogen removal can be installed additionally in the upstream of an existing SRGO HDS reactor to achieve higher desulphurization or can be designed with the grass roots units.

The inhibition effects of nitrogen on VGO hydrocracking have been studied at different temperatures and the reaction has been found to be highly non-linear in nature and the conversion rapidly drops and the slope becomes less steep as the nitrogen level increases. At higher reaction temperature, the drop in activity or conversion with feed nitrogen is less than that in lower temperatures due to the higher rate of desorption of nitrogen compounds at elevated temperatures. The drop in conversion with nitrogen compounds present in VGO indicates the presence of organo nitrogen compounds having higher basicity compared to the nitrogen compounds by pyridine doping. The hysteresis exists in adsorption/desorption of nitrogen compounds and it indicates that desorption is a very slow process. With the increase of nitrogen compounds in the feed, the conversion drops rapidly and it takes long time to reach an equilibrium value. Similarly, with the step increase in reactor temperature, nitrogen desorption takes place at a slow rate and the conversion level comes to an equilibrium value after 8 days.

The observed effects of nitrogen inhibition on SRGO hydrotreating and VGO hydrocracking conversion are explained reasonably well by kinetic models.