磷添加方式对NiMo/Al2O3催化剂加氢脱硫性能的影响

采用分步浸渍法制备了不同磷添加方式改性的NiMo/Al₂O₃催化剂,在固定床微反装置上考察了该系列催化剂对焦炉煤气中噻吩加氢脱硫（HDS）性能的影响,采用BET、X射线衍射（XRD）、H₂程序升温还原（H₂-TPR）、NH₃程序升温脱附（NH₃-TPD）、C₄H₄S(H₂)程序升温脱附[C₄H₄S(H₂)-TPD]、X射线光电子能谱（XPS）、高清透射电镜（HRTEM）和拉曼（Raman）等分析手段对催化剂进行表征。结果表明,不同磷添加方式制备NiMo/Al₂O₃催化剂的HDS性能存在较大差异。其中,催化剂PNi-Mo/Al和PMo-Ni/Al表面弱吸附解离活性位增强,对焦炉煤气中噻吩有较好的低温加氢脱硫活性,以含292.5mg/m³噻吩的模拟焦炉煤气为原料时,PNi-Mo/Al在250℃下对噻吩的脱硫率达61%。对于PNi-Mo/Al和PMo-Ni/Al催化剂,先浸渍P、Ni或者P、Mo时,P优先和载体Al₂O₃作用,减弱了活性金属组分Ni、Mo与载体间的相互作用,而又防止Ni或者Mo与载体间相互作用过低而聚集,提高了Ni、Mo在载体表面的均匀分散,生成能够促进硫化形成Ⅱ型活性相Ni-Mo-S的NiMoO₄物种。NiMoO₄和MoO₃之间的协同作用提高了催化剂的硫化度,使HDS活性得以提高。     

负载型Pt-Fe/Al2O3催化剂用于室温催化氧化甲醛

采用胶体沉积法制备不同载体（Ni₂O₃、Co₃O₄、TiO₂、Al₂O₃）的Pt-Fe/MeO_x催化剂用于甲醛室温催化氧化。活性测试表明,以γ-Al₂O₃为载体的Pt-Fe/Al₂O₃催化剂具有较高的催化活性,在25℃时甲醛的转化率可达到100%,而且Pt-Fe/ Al₂O₃催化剂还表现出良好的稳定性。采用各种表征技术对Pt-Fe/Al₂O₃的形貌、价态及氧化还原性等物理化学性质进行了研究,结果表明：Pt-Fe/Al₂O₃催化剂中Pt物种和Fe物种在Al₂O₃载体的表面上均匀分散;二者之间存在着较强的相互作用,在Al₂O₃载体的表面上形成一些类似Pt-O-Fe活性物种,有效促进了Pt-Fe/Al₂O₃催化性能,从而显示出较高的氧化活性。     

Sn对V2O5/Al2O3催化剂在异丁烷脱氢反应中的影响

以Al₂O₃为载体,采用等体积浸渍法制备了负载型高分散氧化钒催化剂（12%V₂O₅/Al₂O₃）,并选择Sn作为助剂对12%V₂O₅/Al₂O₃催化剂的表面性质进行调控,采用XRD、N₂等温吸脱附、NH₃-TPD、H₂-TPR、XPS、TEM和Raman光谱等方法对催化剂进行表征,结合活性评价实验,研究了催化剂表面物种分散状态、酸性和活性物种价态的变化与异丁烷脱氢活性和稳定性之间的关系。表征结果显示,Sn对V₂O₅/Al₂O₃表面的酸性和V物种在催化剂表面的分布和价态具有一定的调节作用,当Sn质量分数为1%时,氧化锡在催化剂表面分散均匀,对表面积和孔结构影响较小,同时,表面酸性变化较小,表面低价态的钒物种增多。活性评价结果表明,该催化剂在临氢反应条件下保持了最佳的脱氢活性及稳定性,异丁烷脱氢反应480min后,异丁烷转化率为46.8%,异丁烯收率为39.8%。     

Co/Si/Mo/Ni/Al2O3催化剂对汽油加氢脱硫性能的影响

为了研究活性组分的负载对催化剂加氢脱硫性能的影响,设计并制备了Co/Si/Mo/Ni/Al₂O₃多元复合催化剂。通过固定床催化剂评价装置对其进行二苯并噻吩加氢脱硫反应活性评价,并利用X射线衍射仪（XRD）、N₂吸附测试仪、X射线光电子能谱仪（XPS）、扫描电子显微镜（SEM）和Mapping等分析测试手段对催化剂进行表征。结果表明,复合催化剂具有优良的加氢脱硫性能,当活性组分负载量为（0.5%Co）/（1.5%Si）/（3.0%Mo）/（10.0%Ni）/Al₂O₃时,其加氢脱硫性能最高可达到96.1%。     

耐硫甲烷化反应的研究进展

耐硫甲烷化工艺对含硫气氛和低H₂/CO比均有良好的适应性,是甲烷化技术发展的重要方向。其中Mo基催化剂是研究最为广泛的耐硫甲烷化催化剂。重点介绍了Al₂O₃、ZrO₂、CeO₂和CeO₂-Al₂O₃载体以及CoO、NiO助剂对Mo基催化剂耐硫甲烷化性能的影响;分析了催化剂的硫化机理以及CoO、NiO助剂和CeO₂载体在硫化过程中的作用,指出硫化温度是影响催化剂的物种分布和催化性能的重要因素;阐述了耐硫甲烷化反应的机理;对甲烷化催化剂的研究方向进行展望。     

Ni-Mn/Al2O3催化剂在浆态床中CO甲烷化催化性能

采用共浸渍法制备了Ni-Mn/Al₂O₃催化剂,考察了助剂Mn的含量对催化剂结构及浆态床CO甲烷化性能的影响。采用XRD、H₂-TPR、BET、TEM、H₂-化学吸附等表征对催化剂进行了测试分析,结果表明,Mn助剂的引入能够促进Ni物种在载体表面的分散,减弱Ni物种与载体的相互作用,降低催化剂的还原温度,提高催化剂的比表面积,减小活性金属Ni的晶粒尺寸。随着Mn含量的增加,Ni-Mn/Al₂O₃催化剂的甲烷化性能先升后降,其中以Mn含量为4%（质量分数）时的催化甲烷化性能最佳,添加过量的Mn导致活性组分Ni被部分覆盖,催化甲烷化性能下降。通过对16Ni4Mn/Al₂O₃催化剂样品的浆态床反应温度及反应压力的研究发现,当反应温度为280℃、反应压力为1.5 MPa时,催化剂样品16Ni4Mn/Al₂O₃的CO转化率及CH₄选择性分别达到96.2%和88.8%。     

载体预处理对Mo/Al2O3催化剂催化裂解汽油加氢脱氮性能的影响

乙烯裂解原料劣质化导致裂解汽油中氮含量显著增加，开发新型加氢脱氮(HDN)催化体系以适应高氮裂解汽油工况具有重要意义。以常用的Mo/Al₂O₃为模型催化剂，通过控制载体预处理方式来调控催化剂微观结构，并采用X射线衍射(XRD)、H₂程序升温还原(H₂-TPR)、高分辨率透射电镜(HRTEM)、X射线光电子能谱(XPS)、吡啶红外(Py-IR)等表征手段对催化剂进行表征，系统地研究了载体预处理方式对Mo/Al₂O₃催化剂结构及HDN催化反应性能的影响。结果表明：对于Mo/Al₂O₃催化剂，载体经酸、碱预处理前后MoS₂活性组分均呈单层分散状态；酸、碱预处理可调变催化剂表面酸性、活性相与载体作用强度，并最终影响钼物种硫化度以及表面S和Mo物质的量之比(S/Mo比)；吡啶HDN反应受加氢(HYD)和C—N氢解(CNH)共同作用：低吡啶转化率(小于20%)下HDN主要与邻近不饱和配位位点(CUS)数...     

Ni/Al2O3-SiO2催化剂表面性质及顺酐加氢性能

以Al₂O₃质量分数为10%的Al₂O₃-SiO₂复合氧化物为载体,通过浸渍法制备一系列不同Ni负载量的Ni/Al₂O₃-SiO₂催化剂。运用BET、XRD、H₂-TPR和NH₃-TPD-MS方法研究催化剂表面性质随活性金属Ni负载量的变化规律,探讨催化剂表面性质的变化对其顺酐加氢活性、选择性及催化剂稳定性的影响。结果表明,Ni/Al₂O₃-SiO₂催化剂中的Ni质量分数由5.0%增加至12.5%时,γ-丁内酯收率由7.9%快速增至38.9%,进一步增加Ni质量分数至20.0%,γ-丁内酯收率增加趋于平缓。催化剂中Ni活性物种与催化剂酸性中心的数量是影响催化剂顺酐加氢活性的主要原因。     

助剂Zn对PtSn/Al2O3催化剂丙烷脱氢性能的影响

以羰基铂锡化合物为前体,采用浸渍法将其负载于Zn改性Al₂O₃载体上制备了PtSn/xZn-Al₂O₃催化剂,考察了Zn的添加对催化剂丙烷脱氢性能的影响。采用N₂吸附-脱附、X射线衍射（XRD）、吡啶红外吸附（Py-IR）、氨气程序升温脱附（NH₃-TPD）、透射电子显微镜（TEM）等手段对催化剂的孔结构、表面酸性以及积炭行为进行了分析。结果表明,PtSn/xZn-Al₂O₃催化剂孔道以介孔为主,孔径集中分布于8～10nm;Zn助剂的添加,在催化剂表面会形成ZnO物种,可使PtSn/Al₂O₃催化剂上的金属颗粒粒径减小、分散更加均匀;Zn的加入能有效降低催化剂表面酸量,主要表现为L中强/强酸中心的降低,随着Zn含量的增加,催化剂表面酸量先减少后增加。少量Zn的存在可使PtSn/Al₂O₃丙烯选择性和稳定性显著提高,但过量Zn的加入会降低催化剂的脱氢活性,适宜Zn的质量分数为0.75%～1.0%。反应后催化剂表面积炭主要表现为烯烃性质和芳香烃性质,Zn的添加可有效抑制积炭的形成,提高催化剂稳定性。     

基于镁铝水滑石的Mo/Al2O3-MgO催化剂制备及其加氢脱硫性能

生产低硫或无硫柴油是当今世界范围内清洁燃料发展的趋势,加氢脱硫（HDS）是大规模生产清洁柴油最为有效的技术之一,而研制高活性的HDS催化剂成为该技术的关键。以镁铝水滑石与氧化铝的复合氧化物为载体,通过等体积浸渍法制备了一系列Mo/Al₂O₃-MgO催化剂,以二苯并噻吩（DBT）的正庚烷溶液为原料,在固定床反应器上评价所得催化剂的HDS活性,考察了不同镁铝比的水滑石、焙烧温度和添加量对催化剂物化性质和催化性能的影响。研究结果表明,镁铝比、焙烧温度和添加量均影响催化剂的酸性、金属还原性、硫化性能和MoS₂片晶的堆垛度等,当镁铝摩尔比为3、焙烧温度为800℃、成型时水滑石加入量为10%（质量分数）时,所制备催化剂的HDS活性最高,其脱硫率可达96.2%。这是由于该催化剂的酸性较适宜,活性组分与载体间的相互作用力适中,活性组分更易硫化,有助于提高MoS₂片晶的堆垛度进而改善催化剂的HDS性能。     

Performance of spent sulfide catalysts in hydrodesulfurization of straight run and nitrogen-removed gas oils

After the test run of several months two kinds of commercial catalysts (NiMo/Al₂O₃ and CoMo/Al₂O₃) were examined in hydrodesulfurization (HDS) of straight run (SRGO) and nitrogen-removed gas oils, at 340 °C under 50 kg/cm² H₂. Hydrogen renewal between stages was attempted to show additional inhibition effects of the by-products such as H₂S and NH₃. Spent NiMo/Al₂O₃ and CoMo/Al₂O₃ catalysts showed contrasting activities in HDS and susceptibility to nitrogen species, according to their catalytic natures, compared to those of their virgin ones. HDS over spent NiMo/Al₂O₃ was significantly improved by removal of nitrogen species, while that over spent CoMo/Al₂O₃ was much improved by H₂ refreshment. The activity for refractory sulfur species such as 4,6-dimethyldibenzothiophene was reduced more severely than that for the reactive sulfur species such as benzothiophenes over spent catalysts. The effects of both two-stage hydrodesulfurization and nitrogen-removal were markedly reduced over the spent NiMo when compared with those over virgin NiMo one. The acidity of the catalysts was correlated with the inhibition susceptibility by nitrogen species as well as H₂S and NH₃. Spent catalysts apparently lost their activity due to the carbon deposition, which covered the active sites more preferentially. The spent NiMo catalyst carried more deposited carbon with larger C/H ratio and nitrogen content. Higher acidity was found to be present on the NiMo catalyst, but this was greatly decreased by the carbon deposition. Additionally, the reactivity of nitrogen species in HDS was briefly discussed in relation to the acidity of the catalyst and its deactivation by carbon deposition.     

柠檬酸引入方式对CoMo/TiO2-Al2O3催化剂加氢脱硫性能的影响

采用改进溶胶-凝胶法制备的TiO_2-Al_2O_3作复合载体,制备不同柠檬酸引入方式改性的CoMo/TiO_2-Al_2O_3加氢脱硫催化剂。利用低温N_2吸附-脱附、XRD、SEM和H_2-TPR等对催化剂进行表征,并采用固定床反应器对催化剂加氢脱硫性能进行评价。结果表明,后处理法制备的催化剂比表面积相对较大,孔道结构较好,活性金属组分以无定形形态均匀分散在载体表面,一定程度上减弱了其与载体间的相互作用;该催化剂可以延缓Co硫化,并且络合生成较多易于硫化还原的Mo物种,利于MoS_2在催化剂表面的堆叠,生成更多的Co-Mo-S(Ⅱ)活性相,因而相应的CoMo催化剂对噻吩加氢脱硫转化率显著提高。     

Hydrodesulfurization activity of CoMo and NiMo supported on Al2O3–TiO2 for some model compounds and gas oils

Catalytic activities of Al₂O₃–TiO₂ supporting CoMo and NiMo sulfides (CoMoS and NiMoS) catalysts were examined in the transalkylation of isopropylbenzene and hydrogenation of naphthalene as well as the hydrodesulfurization (HDS) of model sulfur compounds, conventional gas oil (GO), and light cycle oil (LCO). Al₂O₃–TiO₂ supporting catalysts exhibited higher activities for these reactions except for the HDS of the gas oil than a reference Al₂O₃ supporting catalyst, indicating the correlation of these activities. Generally, more content of TiO₂ promoted the activities. Inferior activity of the catalyst for HDS of the gas oil is ascribed to its inferior activity for HDS of dibenzothiophene (DBT) in gas oil as well as in model solvent decane, while the refractory 4,6-dimethyldibenzothiophene (4,6-DMDBT) in gas oil as well as in decane was more desulfurized on the catalyst. Characteristic features of Al₂O₃–TiO₂ catalyst are discussed based on the paper results.     

Hydrodesulfurization over noble metals supported on ZSM-5 zeolites

Pt/HZSM-5 showed high and stable catalytic activity for the hydrodesulfurization of thiophene at 400°C and its catalytic activity was higher than that of commercial CoMo/Al₂O₃ catalyst. Pt/HZSM-5 zeolite was not poisoned by hydrogen sulfide in the hydrodesulfurization of thiophene and hydrocracking of hydrocarbons. The catalytic activity of Pt/HZSM-5 decreased with increase of SiO₂/Al₂O₃ ratio in HZSM-5. The Brønsted acid site of HZSM-5 and spillover hydrogen formed on Pt particle in Pt/HZSM-5 catalyst play an important role for the hydrodesulfurization of thiophene.     

Highly active sulfided CoMo catalyst on nano-structured TiO2

High surface area (>300 m² g⁻¹) nano-structured TiO₂ oxides (ns-T) were used as CoMo hydrodesulfurization catalyst support. Cylindrical extrudates were impregnated by incipient wetness with Mo (2.8 Mo at. nm⁻²) and Co (atomic ratio Co/(Co + Mo) = 0.3). Characterization of impregnated precursors was carried out by N₂ physisorption, XRD and atomic absorption and laser-Raman spectroscopies. Sulfided catalysts (400 °C, H₂S/H₂) were studied by X-ray photoelectronic spectroscopy. As indicated by XRD and after various preparation steps (extrusion, Mo and Co impregnation and sulfiding) the nano-structured material was well preserved. XPS analyses showed that Co and Mo dispersion over the ns-T support was much higher than that on alumina. Very high surface S concentration suggested that even ns-T was partially sulfided during catalyst activation. Dibenzothiophene hydrodesulfurization activity (5.73 MPa, 320 °C, n-hexadecane as solvent) of CoMo/ns-T was two-fold to that of an alumina-supported commercial CoMo catalyst. The improvement was even more remarkable in intrinsic pseudo kinetic constant basis. No important differences in selectivity over the catalysts supported on either Al₂O₃ or ns-T were observed, where direct desulfurization to biphenyl was favored. Both Mo dispersion and sulfidability were enhanced on the ns-T support where Mo⁴⁺ fraction was notably increased (100%) as to that found on CoMo/Al₂O₃.     

Hydrodesulfurization of dibenzothiophenes over molybdenum catalyst supported on TiO2–Al2O3

Composite types of TiO₂–Al₂O₃ supports, which are γ-aluminas coated by titania, have been prepared by chemical vapor deposition (CVD), using TiCl₄ as a precursor. Then supported molybdenum catalysts have been prepared by an impregnation method. As supports, we employed γ-alumina, anatase types of titania, and composite types of TiO₂–Al₂O₃ with different loadings of TiO₂. We studied the conversion of Mo from oxidic to sulfidic state through sulfurization by X-ray photoelectron spectroscopy (XPS). The obtained spectra unambiguously revealed the higher reducibility from oxidic to sulfidic molybdenum species on the TiO₂ and TiO₂–Al₂O₃ supports compared to that on the Al₂O₃ support. Higher TiO₂ loadings of the TiO₂–Al₂O₃ composite support led to higher reducibility for molybdenum species. Furthermore, the catalytic behavior of supported molybdenum catalysts has been investigated for hydrodesulfurization (HDS) of dibenzothiophene (DBT) and methyl-substituted DBT derivatives. The conversion over the TiO₂–Al₂O₃ supported Mo catalysts, in particular for the 4,6-dimethyl-DBT, is much higher than that obtained over Al₂O₃ supported Mo catalyst. The ratio of the corresponding cyclohexylbenzene (CHB)/biphenyl (BP) derivatives is increased over the Mo/TiO₂–Al₂O₃. This indicates that the prehydrogenation of an aromatic ring plays an important role in the HDS of DBT derivatives over TiO₂–Al₂O₃ supported catalysts.     

Performance of CoMoS catalysts supported on nanoporous carbon in the hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene

A new type of nanoporous carbon with a large surface area and mesoporosity was prepared and used as a support for a hydrodesulfurization (HDS) catalyst. The overall activity of CoMoS catalysts for the HDS of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) is affected by the type of support used for preparing the catalyst and decreases in the order of CoMo/(nanoporous carbon)>CoMo/(activated carbon)>CoMo/Al₂O₃. The surface area of activated carbon is the largest among these three types of supports but is significantly lowered after metal loading during the preparation of the catalyst. On the other hand, the surface areas of the other two supports are largely preserved after metal loading. The intrinsic activity of the catalysts, estimated by dividing the overall HDS rate by the amount of NO adsorbed on the catalyst, shows a trend that is different from that for the overall activity, and follows the order of CoMo/(nanoporous carbon)≈CoMo/Al₂O₃>CoMo/(activated carbon). The low intrinsic activity of CoMo/(activated carbon) compared to that of the other two catalysts, particularly in the case of 4,6-DMDBT HDS, is obtained because the diffusion of reactants into the catalyst pores is significantly limited. This is not observed with other catalysts supported on nanoporous carbon and alumina. From the results of this study, we conclude that nanoporous carbon is a promising support for HDS catalysts, compared to conventional supports such as alumina and activated carbon, because it has a large surface area and a high mesoporosity, both of which are beneficial to the preparation of highly dispersed metal catalysts without significant pore blocking due to the dispersed metal particles.     

Effect of synergism between potassium and phosphorus on selective hydrodesulfurization performance of Co–Mo/Al2O3 FCC gasoline hydro-upgrading catalyst

A series of potassium and/or phosphorus modified Co–Mo/Al₂O₃ FCC gasoline hydro-upgrading catalysts were prepared and the influences of potassium and/or phosphorus on the morphology, acidity and catalytic performance of the resulting catalysts were studied in the present investigation. The results showed that, compared to the single potassium or phosphorus modified catalyst, the Co–Mo–K–P/Al₂O₃ catalyst in which the atomic ratio of potassium to phosphorus was 2.0 could better balance the hydrodesulfurization and olefin saturation activities due to the compromised dispersion and stacking of MoS₂ slabs on the support as well as the good acidity property, and thus present the excellent selectivity in hydrodesulfurization. The present investigation also demonstrates the superiority of adjusting the K/P atomic ratio in optimizing the structure of MoS₂ slabs and thus provides a novel method for developing highly selective hydrodesulfurization catalysts.     

柠檬酸促进NiMoP催化剂上二苯并噻吩脱硫反应

车用燃油中的含硫化合物是大气主要污染物SOx的主要来源,降低燃油中该类化合物含量是减少汽车尾气SOx排放量的重要保障。燃油加氢脱硫技术是满足这一环保要求的最重要手段,技术的关键是研制高效加氢脱硫催化剂。通过在NiMoP浸渍液中添加不同含量的柠檬酸,制备一系列NiMoP/Al₂O₃催化剂,以二苯并噻吩为模型化合物,考察催化剂在制备过程中添加柠檬酸对NiMoP/Al₂O₃催化剂加氢脱硫性能的影响。结果表明,柠檬酸的加入能够提高催化剂的加氢脱硫性能,明显改善NiMoP/Al₂O₃催化剂的加氢性能。     

Catalytic activities of Co(Ni)Mo/TiO2–Al2O3 catalysts in gasoil and thiophene HDS and pyridine HDN: effect of the TiO2–Al2O3 composition

The effect of the TiO₂–Al₂O₃ mixed oxide support composition on the hydrodesulfurization (HDS) of gasoil and the simultaneous HDS and hydrodenitrogenation (HDN) of gasoil+pyridine was studied over two series of CoMo and NiMo catalysts. The intrinsic activities for gasoil HDS and pyridine HDN were significantly increased by increasing the amount of TiO₂ into the support, and particularly over rich- and pure-TiO₂-based catalysts. It is suggested that the increase in activity be due to an improvement in reducing and sulfiding of molybdena over TiO₂. The inhibiting effect of pyridine on gasoil HDS was found to be similar for all the catalysts, i.e., was independent of the support composition. The ranking of the catalysts for the gasoil HDS test differed from that obtained for the thiophene test at different hydrogen pressures. In the case of gasoil HDS, the activity increases with TiO₂ content and large differences are observed between the catalysts supported on pure Al₂O₃ and pure TiO₂. In contrast, in the case of the thiophene test, the pure Al₂O₃-based catalyst appeared relatively more active than the catalysts supported on mixed oxides. Also, in the thiophene test the difference in intrinsic activity between the pure Al₂O₃-based catalyst appeared relatively more active than the catalysts supported on mixed oxides. Also in the thiophene test, the difference in intrinsic activity between the pure Al₂O₃- and pure TiO₂-based catalysts is relatively small and dependent on the H₂ pressure used. Such differences in activity trend among the gasoil and the thiophene tests are due to a different sensitivity of the catalysts (by different support or promoter) to the experimental conditions used. The results of the effect of the H₂ partial pressure on the thiophene HDS, and on the effect of H₂S concentration on gasoil HDS demonstrate the importance of these parameters, in addition to the nature of the reactant, to perform an adequate catalyst ranking.