Co调变MoS2催化剂的作用本质及其FCC汽油选择性加氢脱硫机理

采用含硫前驱体四硫代钼酸铵直接构建MoS₂催化剂,通过调变Co/Mo原子比深入认识Co调变MoS₂催化剂的作用本质及其FCC汽油选择性加氢脱硫机理。借助XRD、HRTEM、XPS、H₂-TPR和Py-FTIR表征发现,Co/Mo原子比能够影响催化剂的活性相微观结构组成,从而影响催化剂的加氢脱硫活性和选择性。当Co/Mo（atomic ratio）<0.2时,助剂Co原子倾向于占据MoS₂相的边角位而形成CoMoS活性相,明显提高了催化剂的加氢脱硫活性;当0.2 < Co/Mo（atomic ratio） < 0.6时,助剂Co在催化剂表面形成适量的Co₉S₈相,其产生的溢流氢能提高硫化物的脱除活性而对烯烃饱和活性的影响较小;当Co/Mo（atomic ratio）>0.6时,过量的Co会形成大颗粒的Co₉S₈相,阻碍硫化物和烯烃与催化剂活性中心的接触,从而降低催化剂的活性和选择性。     

Ni2P和MoS2催化剂在二苯并噻吩加氢脱硫反应中的氢溢流效应

对分层装填的Ni₂P//MoS₂催化剂上的二苯并噻吩加氢脱硫反应进行了研究。结果表明,分层装填的Ni₂P/Al₂O₃和MoS₂/Al₂O₃催化剂在二苯并噻吩加氢脱硫反应中存在氢溢流效应,氢溢流有助于提高MoS₂催化剂的活性位密度和加氢脱硫反应速率。由于Ni₂P比NiS_x具有更强的氢分子解离能力,Ni₂P//MoS₂催化体系的氢溢流因子略高于NiS_x//MoS₂;相对于NiS_x,Ni₂P对MoS₂催化剂是更好的助剂。     

高效稳定的MoS2-TiO2纳米复合催化剂用于浆态床菲催化加氢(英文)

浆态床加氢是一种先进的非常规石油资源(重油等)加氢提质技术,它采用分散型催化剂以提高催化剂与原料中的沥青质等大分子的接触程度.沥青质等大分子中多环芳烃的快速转化是浆态床重油加氢技术的挑战,因此设计高活性的加氢催化剂是浆态床加氢技术的关键.作为典型的二维层状材料,分散型MoS₂催化剂表现出较好的催化加氢性能.然而,纳米尺寸的分散型MoS₂催化剂的稳定性有待提高,在高温高压下MoS₂片层会折叠并聚集成较大的颗粒以降低其表面能.MoS₂颗粒的生长会导致其悬浮性降低和边缘活性位点暴露量减少,因而降低催化剂的活性和寿命.因此,急需设计开发高性能的分散型MoS₂纳米催化剂,从而解决MoS₂层在高温高压条件下的折叠和聚集难题,提高MoS₂纳米催化剂的催化加氢活性和稳定性.纳米复合材料的构建可以有效地解决活性组分的团聚问题.近年来, Janus纳米复合材料因其在催化方面的广泛应用引起了科研人员的关注.此外,复合材料中各组分的种类对其催化活性有显著影响...     

表面活性剂对水热法合成MoS2加氢脱硫催化剂的影响

采用水热法合成了MoS₂加氢脱硫催化剂,用物理吸附、XRD、SEM、TEM等手段对催化剂进行表征,并以噻吩为模型化合物研究不同类型表面活性剂对合成MoS₂催化剂活性的影响。结果表明,加入表面活性剂制备的催化剂颗粒疏松均匀,比表面积、孔容、孔径都较大,并且MoS₂层状堆叠数目增加;所制催化剂在噻吩加氢脱硫反应中均显示出较好的催化活性,在573 K、4.0 MPa条件下,噻吩加氢脱硫的转化率均大于97.0%,加入阳离子表面活性剂的Mo-S-C催化活性最高,噻吩转化率可达到99.9%。MoS₂催化剂的活性顺序为Mo-S-C>Mo-S-S>Mo-S-P>Mo-S-N。     

绿色合成介孔碳负载(Ni)MoS2加氢脱硫催化剂

以Anderson结构Ni-Mo杂多酸簇(NH₄)₄[NiMo₆O₂₄H₆]·5H₂O、硫脲、柠檬酸、氯化钠为原料,采用冻干法得到前驱体后焙烧、洗涤得到介孔碳骨架负载(Ni)MoS₂纳米颗粒的加氢脱硫催化剂,考察了其对二苯并噻吩的加氢脱硫活性,并采用X射线衍射、N₂低温吸附-脱附、拉曼光谱、X光电子能谱、扫描电子显微镜、高分辨透射电镜、程序升温还原等表征手段对催化剂进行了分析。结果表明,介孔碳骨架负载(Ni)MoS₂纳米颗粒催化剂具有较弱的载体-金属相互作用,MoS₂纳米颗粒平均长度较短(4.9 nm),层数适宜(4.8),NiMoS活性相含量较高,二苯并噻吩的转化率可达94.1%,反应速率常数及活性位转换频率分别可达1.7×10^-6 mol/(g·s)和2.8×10^-3 s^-1。该方法利用原位生成的氯化...     

Ni2P和MoS2催化剂在喹啉加氢脱氮反应中的协同效应

设计实验证明了Ni₂P和MoS₂催化剂在喹啉加氢脱氮反应中存在协同效应,该协同效应能够用氢溢流遥控模型理论解释。Ni₂P//MoS₂的协同因子随反应温度升高而减小,并且略微大于相同反应条件下NiS_x//MoS₂的协同因子。Ni₂P产生的溢流氢能够提高MoS₂催化剂上加氢活性位的数量,促使Ni₂P//MoS₂催化体系增加1,2,3,4-四氢喹啉和5,6,7,8-四氢喹啉加氢生成十氢喹啉的速率,提高其脱氮活性;因此,Ni₂P对MoS₂催化剂是很好的助剂。     

微波水热制备Fe-Zr催化剂及其CO加氢制烯烃性能研究

以ZrO（NO₃）₂·2H₂O和Fe（NO₃）₃·9H₂O为原料,采用微波水热法制备了不同Fe₂O₃/ZrO₂物质的量比的Fe-Zr催化剂,并经K改性,研究了其催化CO加氢一步法合成低碳烯烃性能。采用XRD、SEM、TEM和N₂吸附-脱附等手段对其物相、形貌和比表面积等进行了表征。结果表明,与共沉淀法相比,微波水热制备的Fe-Zr催化剂颗粒粒径均一,具有相对较小的比表面积和较大的孔径;在CO加氢反应中,Zr助剂的添加显著改善了产物分布,Fe、Zr间适宜的相互作用和相对较大的孔径,有利于抑制CH₄的生成,提高烯烃选择性。随着Fe₂O₃/ZrO₂物质的量比的降低,Fe、Zr间相互作用逐渐增强,烯烃选择性和收率先增加后降低。当Fe₂O₃/ZrO₂物质的量比为75：25时,在340 ℃、1.5 MPa、1 000 h^-1和H₂/CO物质的量比为2的条件下,烯烷比（O/P）达4.86,总烯烃收率达62.57 g/m³。     

硫代硫酸铵预硫化的Mo/AC催化剂加氢脱硫性能的研究

采用等体积浸渍法将硫代硫酸铵(ATS)负载在Mo/AC催化剂上,制备了器外预硫化的Mo/AC-ATS催化剂;以噻吩加氢脱硫(HDS)为探针反应,考察了活化温度和活化时间对预硫化催化剂加氢脱硫活性的影响。研究发现,300 ℃下活化0.5 h所得到的预硫化催化剂具有最好的加氢脱硫活性。与传统硫化剂CS₂和DMDS硫化的催化剂相比,采用Mo/AC-ATS催化剂,在最佳活化条件下,噻吩转化率分别提高了34%和42%。XPS、TPR-MS和TEM等表征结果显示,预硫化的Mo/AC-ATS催化剂中Mo⁴⁺含量较高,这是其具有较高加氢脱硫活性的主要原因。     

磷含量对NiMo/γ-Al2O3催化剂活性相结构的影响

采用程序升温还原（TPR）、高分辨透射电镜（HRTEM）和X射线光电子能谱（XPS）表征手段对共浸渍法制备的不同磷含量NiMo/γ-Al₂O₃催化剂进行了表征,研究了磷含量对NiMo/γ-Al₂O₃催化剂活性相结构的影响。TPR研究表明,磷能够减少四面体配位Mo物种的数量,增加八面体配位Mo物种的数量,促进高活性Ⅱ型"Ni-Mo-S"活性相的形成。HRTEM研究表明,随磷含量的增加,MoS₂颗粒堆积层数增加,催化剂的加氢选择性提高;适量磷能够增加边角位有效Mo原子的分散度(fMo),增加催化剂表面加氢脱硫（HDS）和加氢脱氮（HDN）活性位的数量。上述结论得到了XPS表征的证实：适量磷增加了催化剂表面Mo原子浓度、提高有效助剂比率（PR）和提升比率（Ni/Mo）,相应催化剂表现出最高的HDS和HDN活性;但过高磷含量能够引起MoS₂颗粒过度堆积,片层长度过长,导致活性位数量减少,催化活性降低。     

二苯并噻吩在分散型钼催化剂和原位产生的氢存在下的加氢脱硫 Ⅱ.原位氢和分子氢的比较

研究了水/甲苯乳化液中二苯并噻吩(硫芴)在分散型钼酸、磷钼酸和四硫钼酸铵催化剂存在下的加氢脱硫反应.反应在高压釜中于340℃及三种不同的气氛即H2,H2/H2O和CO/H2O(CO和H2O经水煤气转换反应(WGSR)产生原位氢)的存在下进行.用GC和GC-MS鉴定、分析了气体和液体产物的组成.结果表明:对硫芴的加氢脱硫反应,在分散型钼酸和磷钼酸存在下,原位产生的氢比加入的分子氢更为有效.动力学研究结果表明:WGSR反应比硫芴的加氢脱硫反应快5～10倍,说明在原位氢存在下硫芴的加氢脱硫反应是速度控制步骤.总之,试验结果证实,在分散型催化剂和原位氢存在下的加氢过程是重油乳状液改质和破乳的有效方法.     

Ring-opening metathesis polymerization of norbornene and norbornadiene by tungsten(II) and molybdenum(II) complexes

The reaction of norbornene (NBE) and norbornadiene (NBD) in the presence of seven-coordinate tungsten(II) and molybdenum(II) complexes of the [(CO)₄M(μ-Cl)₃M(SnCl₃)(CO)₃] and [MCl(M′Cl₃)(CO)₃(NCMe)₂] (M=W, Mo; M′=Sn, Ge) types leads to ring-opening metathesis polymerization (ROMP) and to the formation of high molecular weight polymers. The geometric structure of these polymers was determined by means of ¹H- and ¹³C-NMR spectroscopy. The monitoring of the reaction between cyclic olefins and the metal complex by means of ¹H-NMR spectroscopy allowed us to observe the coordination of NBD to metal atoms in the initiation step of the polymerization process. Compounds of the [MCl(SnCl₃)(CO)₃(η⁴-NBD)] type prepared directly from [(CO)₄M(μ-Cl)₃M(SnCl₃)(CO)₃] or [MCl(M′Cl₃)(CO)₃(NCMe)₂] (M=W, Mo) in the presence of an excess of NBD initiate the ROMP reaction immediately. The detection of the first-formed products in the reaction between the metal complex and cyclic olefins provides valuable information concerning the nature of the initiating species.     

Effect of Support on Catalytic Performance of Photothermal Fischer-Tropsch Synthesis to Produce Lower Olefins over Fe5C2-based Catalysts

Photothermal Fischer-Tropsch synthesis(FTS) has been extensively studied, but few reports were focused on systematically exploring the influence of support on catalytic performance. Herein, a series of Fe₅C₂-based catalysts with different supports was fabricated via a one-step wet-chemical method for photothermal conversion of syngas to lower olefins. Under light irradiation, the optimized Fe₅C₂/α-Al₂O₃ catalyst demonstrated remarkable photothermal FTS activity, delivering selectivity to lower olefins of 50.3% with a CO conversion rate of 52.5%. Characterization studies using X-ray diffraction and Mössbauer spectroscopy analysis revealed that the active catalyst mainly contained Fe₅C₂ nanoparticles on α-Al₂O₃ support. It was found that the weak interaction between active phase and α-Al₂O₃ could promote the formation of Fe₅C₂, which contributed to the high selectivity to lower olefins.     

Phenylbis(2- pyridyl)phosphine: P- vs. N,N′-coordination in carbonylmolybdenum-(O) and -(II) complexes

The first carbonyl molybdenum-(O) and -(II) complexes with phenylbis(2-pyridyl)phosphine (PPhpy₂) have been synthesized. PPhpy₂ reacts with [Mo(CO)₅(NCMe)] to give [Mo(CO)₅(PPhpy₂-P)]. With [Mo(CO)₄(NBD)] (NBD = norbornadiene) it gives [Mo(CO)₄(PPhpy₂-P)₂] when a 2 : 1 ratio is used, or [MO(CO)₄(py₂PhP---N,N′)] for a 1 : 1 ratio. Decarbonylation of any of these pyridylphosphine complexes leads to an oligomer of formula {MO(CO)₃(μ-PPhpy₂)}_n, which is also obtained after heating [MO(CO)₆] in solution with an equimolar amount of PPhpy₂. The oligomer undergoes oxidative addition by iodine or allylbromide to give [MoI₂(CO)₃(py₂PhP---N,N′)], or [MoBr(η³-CH₂CHCH₂)(CO)₂(py₂PhP---N,N′)], respectively. These complexes are also obtained by addition of equimolar amounts of PPhpy₂ to solutions of [MoI₂(CO)₃(NCMe)₂] and MoBr(η³-CH₂CH CH₂)(CO)₂(NCMe)₂, respectively. The ligand tends to act as a P-donor towards molybdenum(O) substrates, and as a chelating N,N′-donor in molybdenum (II) complexes.     

Hydrogenation of Anthracene and Dehydrogenation of Perhydroanthracene on Pt/C Catalysts

The hydrogenation of anthracene on a heterogeneous catalyst containing 3 wt % Pt/C (Aldrich) at 215, 245, and 280°C and the pressures of 40 and 90 atm is studied. The hydrogenation of anthracene to a completely hydrogenated product is considered in detail. The final product (perhydroanthracene) consists of five conformational isomers with total selectivity of more than 99%. The ratio of perhydroanthracene isomers in the end product is shown to be determined by the conditions (P, T) of hydrogenation. The rate of hydrogenation is found to slow upon an increase in the degree of benzene ring saturation. A mixture of perhydroanthracene isomers is dehydrogenated in an autoclave at 260?325°C on 3 wt % Pt/C catalyst (Aldrich) and in a flow reactor at 300–360°C on 3 wt% Pt/Sibunit catalyst. The reactivity of perhydroanthracene isomers in dehydrogenation is shown to differ.     

浸渍沉淀法制备活性炭负载Co-Mo双金属脱硫催化剂

以氧化改性活性炭为载体,尿素为沉淀剂,采用浸渍沉淀法制备了负载型Co-Mo催化剂,并用CO还原SO₂反应作为模型反应考察了催化剂的催化活性。结果表明,催化剂焙烧温度500℃、Co/Mo物质的量比0.45、最佳反应条件(硫化温度为500℃、空速为7 000 mL/(g·h)、CO/SO₂物质的量比为2:1,反应温度为450℃)时,催化剂具有最好的催化活性和选择性。XRD表征结果表明,催化CO还原SO₂反应的活性相为CoS₂和MoS₂,硫化温度影响活性相的形成。该催化剂稳定性好,反应运行24 h后活性仍能保持最高活性的99%。     

Substituted metal carbonyls XXIII . Syntheses of unicoordinated diphosphine complexes of Cr and Mo and their entry into heterobimetallics MM′(CO)10(μ-P-P) [M, M′= Cr, Mo, W; P---P = Ph2P(CH2)nPPh2, n = 2–4] as metalloligands

A series of pentacarbonyl complexes of chromium and molybdenum with unicoordinated-diphosphines, M(CO)₅(η¹-P-P) (P-P = dppe, dppp, dppb) has been prepared by amine oxide-induced phosphine substitution of the binary carbonyls. The basicity of the pendant phosphine groups was demonstrated by their ready conversion to the diphosphine-bridged heterobimetallic complexes (OC)₅M(μ-P-P)M′(CO)₅ (M, M′= Cr, Mo, W; M ≠ M′) in the presence of MCO)₅(CH₃CN). The complexes were characterized by IR and NMR (¹H and ³¹P-{¹H}) spectroscopy.     

Heterobimetallic Mo---Sn complexes. Reactions of [Mo(CO)3(CH3CN)2(Cl)(SnRCl2)] (R = Me, Ph) with 4(4-XC6H4)3 (X = Cl, F, H, Me, MeO)

Three families of heterobimetallic compounds were obtained by reaction of [Mo(CO)₃(CH₃CN)₂(Cl)(SnRCl₂)] (R = Ph, Me) with P(4-XC₆H₄)₃ (X = Cl, F, H, Me, MeO). The type of compound obtained dependent on the solvent and concentration of the starting compound. So, [Mo(CO)₂(CH₃COCH₃)₂(PPh₃)(Cl)(SnRCl₂)]·nCH₃COCH₃ (R = Ph, n = 0.5; R = Me, n = 1) (type I) and [Mo(CO)₃{P(4-XC₆H₄)₃}(μ-Cl)(SnRCl₂)]₂ (R = Ph, X = Cl, F, H, Me, MeO; R = Me, X = Cl, F) (type II) were isolated from acetone solution in ca 0.05 M and 0.1 M concentrations, respectively. However, [Mo(CO)₃(CH₃CN) {P(4-XC₆H₄)₃}(Cl)(SnRCl₂)] (R = Ph, X = H; R = Me, X = Cl, F, H) (type III) were obtained from dichloromethane solution independently of the concentration used. All new complexes showed a seven-coordinate environment at molybdenum, containing Mo---Cl and Mo---Sn bonds. Mössbauer spectra indicated a four-coordination at tin for type III complexes.     

溶剂热一步法制备二硫化钼/亚氧化钛电解水析氢催化剂

通过水热法一步合成了系列二硫化钼/亚氧化钛（MoS₂/Ti_xO_y）复合催化剂,研究了溶剂、硫源和钼源等合成条件对所合成的催化剂电催化析氢活性的影响以及亚氧化钛的作用。结果表明,溶剂、硫源、钼源、亚氧化钛等因素都对催化剂的结构和电解水析氢性能有重要影响。溶剂水、水解可产生铵根离子的硫源和钼源以及亚氧化钛的加入有利于获得具有高析氢活性的催化剂。其中,以水为溶剂、硫代乙酰胺为硫源、钼酸铵为钼源得到的催化剂析氢活性最高,电解水析氢测试中达到10 mA/cm²电流密度时需要的过电势仅为280 mV。     

羰基钴催化烯烃醛化反应中RCOCo(H)2(CO)3还原消去关键步骤的理论研究

在其催化循环过程中,RCOCo(CO)_3与H2_氧化加成生成RCOCO(H)_2(CO)_3,此中间体进一步还原消去生成醛是涉及氢在整个醛化反应催化循环中活化作用的关键步骤,文献[2]认为它是整个循环的控制步骤,由于反应的各中间物光谱无法准确测定,无法分别考察这两个步