浸渍顺序对Mo-Ni加氢催化剂结构和性质的影响

以γ-Al2O3为载体,制备Mo、Ni单组分及双组分催化剂,考察浸渍顺序对催化剂结构的影响.通过氮物理吸附、TPR、和XPS等技术进行表征,结果表明,共浸渍法制备催化剂,有利于活性金属组分的还原,并能提高活性金属组分的分散度,同时使催化剂表面具有较高的Ni/Mo原子比.     

高硫合成气制甲硫醇K2MoO4/SiO2催化剂的研究Ⅰ.镍的促进作用

采用共同浸渍法制备了K2MoO4-NiO/SiO2催化剂,考察了NiO添加量对高硫合成气制甲硫醇K2MoO4/SiO2催化剂性能的影响.活性评价结果表明,添加了NiO的催化剂活性有很大的提高,当Ni/Mo物质的量比为2/9时,CO转化率为72.6%,较未添加NiO的催化剂提高了一倍多.程序升温还原(TPR)表征显示,添加的NiO与Mo有强相互作用,促进了Mo物种的还原.电子自旋共振(ESR)表征显示,反应后的催化剂中可检测到"oxo-Mo(V)"物种和"thio-Mo(V)"物种,K2MoO4-NiO/SiO2催化剂表面主要为"thio-Mo(V)"物种,而K2MoO4/SiO2催化剂表面主要为"oxo-Mo(V)"物种,NiO的添加促进了Mo物种的还原、硫化,可能是造成催化剂活性极大提高的原因.     

载体对负载型过渡金属氮化物催化氨分解性能的影响

采用等体积浸渍法结合NH3程序升温氮化制备出一系列负载型金属Co、Mo氮化物催化剂。并利用XRD、TPD-MS和H2-TPR及氨分解活性测试等手段,考察了载体［Mg(Al)O、MgO和γ-Al₂O₃］对负载型金属氮化物的表面形态及组成的影响。结果表明,（1） 负载催化剂的氨分解速率远远高于非负载的催化剂;（2） 氮的脱附峰可以归为以下三类：a.吸附态的NHx分解;b.氮化物结构转变;c. β-Mo₂N_0.78和Co₂Mo₃Nx 还原成Co和Mo金属;（3） 载体表面的酸碱性和孔结构对其负载的金属氮化物的催化活性和表面形态及化学组成有重要的影响,镁铝复合氧化物MgAlO［n(Al)∶n(Mg)=1∶3］为载体的钴钼双金属氮化物对于氨分解反应具有最好的催化活性。     

SiO2负载双氯基桥联双核Mo(V)催化剂合成、表征及其催化环己烯环氧化性能

合成了SiO2负载双氯基桥联双核Mo(V)催化剂,并用红外光谱、X-光电子能谱测定及UV-vis光谱等方法进行了结构表征.结果表明:SiO2负载双氯基桥联双核Mo(V)中金属Mo(V)离子以双齿配位形式与SiO2表面氧键合,双核Mo(V)间以μ-双氯基桥联.实验发现,其作为催化剂用于环己烯环氧化反应的活性组分是Mo(VI)而不是Mo(V).在反应过程中,经环氧化剂叔丁基过氧化氢(t-BuOOH)处理后,具有很高的催化活性和选择性;研究探讨了其催化环己烯环氧化的反应机理;建立了催化剂中Mo分析和环氧环己烷气相色谱分析新方法;在n(t-BuOOH)=0.1mol,n(C6H10) : n(t-BuOOH) = 3 : 1,溶剂5 mL,催化剂用量(以Mo计) ～0.0216 g,反应温度80℃,时间60min反应条件下,环氧环己烷收率(以t-BuOOH计)在99% 以上,质量分数～ 99.5 %(GC检测).催化剂循环使用5次后,未见活性明显下降,环氧环己烷收率(以t-BuOOH计)仍接近99%.     

乙二胺四乙酸对NiMo/Al_2O_3催化剂加氢脱氮性能的影响

以氧化铝为载体,Ni和Mo为金属活性组分,添加不同含量乙二胺四乙酸,采用等体积浸渍法制备系列Ni Mo(x)/Al_2O_3(x为乙二胺四乙酸与Ni物质的量比)重质油加氢处理催化剂,考察乙二胺四乙酸加入量对催化剂加氢脱氮性能的影响,并采用N_2物理吸附-脱附、XRD和HRTEM等对催化剂进行表征。结果表明,乙二胺四乙酸的加入增强了金属组分与氧化铝载体间的相互作用,降低了MoS_2活性相的堆垛层数和片层长度,促进了活性相的分散。乙二胺四乙酸与Ni物质的量比为0.5时,MoS_2活性相堆垛层数和片层长度达到良好的结合,对应的催化剂Ni Mo(0.5)/Al_2O_3具有最优的加氢脱氮性能。     

纳米自组装催化剂活性金属的分散及其加氢活性

利用不同共浸剂制备纳米自组装催化剂,用BET、XRD和H2-TPR手段考察催化剂中活性金属的分散状态、晶型及其还原性质。结果表明,活性金属在催化剂中的分散状态与催化剂中活性金属的晶型、催化剂的还原性能以及加氢活性密切相关。当催化剂中的活性金属呈单层分散时,八面体配位Mo物种的数量最高,此时催化剂的还原性能和加氢活性最好;当活性金属在载体表面的分散状态变差时,催化剂中八面体配位Mo物种数量逐渐减少,同时催化剂的还原性能和加氢活性也随着变低。     

CoMo/Al_2O_3-SiO_2催化剂原位红外光谱研究

采用原位红外光谱技术,以CO作为探针分子研究了加氢脱硫CoMo/Al2O3-SiO2催化剂的活性吸附位的变化规律。原位硫化温度范围为300~550℃,获得了CoMo/Al2O3-SiO2催化剂的MoS(2110cm2-1)和CoMoS(2070cm-1)活性相在增加硫化温度过程中的转变规律。在CoMo/Al2O3-SiO2催化剂中,当载体中SiO2含量逐渐增加时,能够显著改变催化剂活性相的相对强度变化,表明载体中加入适量的SiO2能够显著改变加氢脱硫CoMo/Al2O3-SiO2催化剂的载体与活性金属(Co和Mo)的相互作用,从而提高金属在加氢催化剂载体上的分散性能,产生更多活性吸附位。     

完全液相法Mo改性CuZnAl的结构与性能研究

考察了过渡金属钼作为助催化剂添加到完全液相法制备的CuZnAl浆态催化剂中,对催化剂结构和CO加氢液相反应的产品分布的影响。Mo改性CuZnAl催化剂在250℃,5.0 MPa,空速为360 mL/(g·h)和V(H2)/V(CO)=1条件下进行活性评价,在500 mL浆态床中CO加氢反应120 h;并运用XRD,H2-TPR,NH3-TPD和BET对催化剂进行表征。结果表明:完全液相法制备的Mo-CuZnAl催化剂对液相CO加氢反应有良好稳定性;Mo助剂能促进铜氧化物在较低温度还原,增强催化剂表面酸性,在温和条件下提高烃,特别是甲烷的选择性。     

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...     

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。     

Effect of carbon black composite (CBC) support properties on hydrodesulfurization performance of sulfided Mo and Co, and carburized Mo, catalysts

Carbon black composites (CBCs) have been prepared by pyrolyzing mixture of a carbon black with polyfurfuryl alcohol and then pretreated by oxidation with nitric acid, gasification with water steam or ammoxidation. The effects of the chemical character of the carrier surface, nature of the active metal phase and pH value of the impregnation solution on the catalytic activity towards the hydrodesulfurization (HDS) of thiophene of the CBC supported Mo (Co) catalysts were determined. It was stated that the catalytic properties of the CBC supported sulfides of Mo or Co and of Mo carbides are affected by the chemical character of the carrier surface. Generally, catalysts supported over basic surface CBC exhibit higher activity than those ones supported over CBC possessing acidic surface character. Co catalysts supported on acidic surface show lower activity (per mol of active metal) than Mo based ones supported on the same carrier. In the case of catalysts supported on basic CBC, Co exhibits distinctly higher activity than Mo. At the experimental conditions adopted for this study, CBC surface properties, active phase nature, and catalyst impregnation pH were found to exert a relatively small influence on both HDS and hydrogenation activities.     

Characterization and catalytic studies of PVD synthesized Mo/V/Nb/Te oxide catalysts

Multicomponent Mo/V/Nb/Te oxide catalysts were synthesized using physical vapor deposition (PVD) onto the substrates of Si wafers and of honeycomb cordierites. The PVD films were prepared at different metal deposition sequences and were subsequently calcined at different temperatures and environment (air or N₂). The PVD films on Si wafer were characterized using several surface techniques, including X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS), and secondary ion mass spectrometry (SIMS). In parallel, PVD films on cordierites were evaluated in a fixed-bed reactor for the selective oxidation of propane to acrylic acid. The combined synthesis, characterization, and reactor studies provided clear evidence that the surface compositions and the catalytic properties of the Mo/V/Nb/Te oxide catalysts depend strongly on the metal deposition sequence, calcination temperature, and calcination environment.     

Catalytic activity of Co,Mo and CoMo supported on NaY zeolite: hydrodesulfurization of gas oil at high pressure

Three series of Co/NaY, Mo/NaY and CoMo/NaY zeolite catalysts with variable metal content, prepared by a conventional impregnation method, were characterized by XRD, IR spectroscopy (oxide state) and acidity measurements (sulfide state), and tested in hydrodesulfurization (HDS) of gas oil at high pressure in the temperature range 275–350°C. The combined results of surface area, XRD and IR showed that in the catalysts with high metal loading a small loss in crystallinity and a partial blockage of the zeolite supercages were produced by Mo oxide species. The number of acid sites, which was lower for the Co/NaY than for the Mo/NaY catalysts, increased with increasing Co or Mo loading, but the strength of the acid sites was stronger for the Co/NaY series. HDS specific activities of the Co/NaY and Mo/NaY monometallic catalysts reached a maximum at very low loadings of Co ( 0.10 at. nm^–2) or Mo ( 0.16 at. nm^–2) by the double action of the metal sulfide species and the strong acid sites generated on the zeolite by the Co or Mo incorporation. In the binary CoMo/NaY catalysts, the synergy between Co and Mo species was significant for high Mo contents only.     

Vm/MOx催化剂对柴油碳烟催化燃烧抗硫中毒性能的比较

用柠檬酸络合助溶的等体积浸渍法制备了不同载体(γ-Al2O3 、SiO2 、TiO2、ZrO2和CeO2)负载的系列钒氧化物催化剂,使用红外光谱对催化剂硫中毒老化后的结构进行表征,采用程序升温氧化反应技术评价了硫老化后的催化剂对柴油碳烟催化燃烧的活性.结果表明,负载钒基氧化物催化剂硫老化后,催化剂表面主要以亚硫酸盐物种...     

M1 to M2 Phase Transformation and Phase Cooperation in Bulk Mixed Metal Mo–V–M–O (M=Te, Nb) Catalysts for Selective Ammoxidation of Propane

In the present study we systematically explored hydrothermal synthesis of bulk mixed metal Mo–V–(Te–Nb)–O catalysts and investigated the bulk characteristics of the resulting M1 and M2 phases as well as their roles in the selective ammoxidation of propane. It was found that unlike Mo–V–Te–Nb–O M1 phases, the Mo–V–Te–O M1 phases may be quantitatively transformed into M2 phases of the same chemical composition indicating that Nb stabilizes the M1 structure. The stabilizing role of Nb and Te was further observed in high resolution TEM studies of Mo–V–(Te–Nb)–O catalysts which indicated that structural order and the M1 phase domain size progressively decreased in this order: Mo–V–Te–Nb–O > Mo–V–Te–O > Mo–V–O. The cooperation between the M1 and M2 phases in propane ammoxidation to acrylonitrile was observed only at low propane conversions suggesting that the M1 phase is the only crystalline phase required for the activity and selectivity of the Mo–V–Te–Nb–O catalysts in propane ammoxidation to acrylonitrile at practical propane conversions.     

重芳烃轻质化催化剂n（Ni）/n（Ni+Mo）的优化与分析

以β分子筛为载体,在保持金属总负载量不变的情况下,采用等体积浸渍法制备了4种不同n（Ni）/n（Ni+Mo）的催化剂。分别采用X射线衍射（XRD）、比表面积测试（BET）、氨程序升温脱附（NH₃-TPD）、氢程序升温还原（H₂-TPR）、氢程序升温脱附（H₂-TPD）和热重-差热分析（TG-DTG）等方法对催化剂进行了表征。结果表明,4种催化剂的酸量和酸强度相近,在n（Ni）/n（Ni+Mo）等于基准+0.2时,Mo与载体之间的相互作用最弱,其氢气吸附量最多且积炭量最少;采用某炼厂重整C₁₀⁺ 重芳烃对4种催化剂进行评价,结果表明n（Ni）/n（Ni+Mo）等于基准+0.2催化剂具有最优的催化活性和稳定性。上述结果表明,影响重芳烃轻质化催化剂活性和稳定性的关键因素是催化剂氢气吸附量的多少,氢气吸附量越多金属表面的溢流氢效应越明显,积炭前驱体被溢流氢及时消除,从而保护了催化剂的加氢活性中心不被积炭覆盖,有助于催化剂在较高活性下保持稳定。     

Screening of PdM and PtM catalysts in a multi-anode direct formic acid fuel cell

Direct formic acid fuel cells (DFAFC) currently employ either Pt-based or Pd-based anode catalysts for oxidation of formic acid. However, improvements are needed in either the activity of Pt-based catalysts or the stability of Pd-based catalysts. In this study, a number of carbon-supported Pt-based and Pd-based catalysts, were prepared by co-depositing PdM (M = Bi, Mo, or V) on Vulcan^® XC-72 carbon black, or depositing another metal (Pb or Sn) on a Pt/C catalyst. These catalysts were systematically evaluated and compared with commercial Pd/C, PtRu/C, and Pt/C catalysts in a multi-anode DFAFC. The PtPb/C and PtSn/C catalysts were found to show significantly higher activities than the commercial Pt/C catalyst, while the PdBi/C provided higher stability than the commercial Pd/C catalyst.     

Promotion effects of Pt and Rh on catalytic performances of Mo/HZSM-5 and Mo/HMCM-22 in selective methane-to-benzene reaction

The promotion effects of Pt and Rh on catalytic performances of Mo/HZSM-5 and Mo/HMCM-22 in selective methane-to-benzene reaction were studied in the presence of additive H₂. The selectivity to naphthalene was effectively suppressed and highly selective and stable benzene formation was obtained by the addition of noble metal to the Mo/HZSM-5 and Mo/HMCM-22 catalysts, due to the suppression of carbon deposition on the Brønsted acid sites of zeolite.     

Co—Mo系耐硫变换催化剂的TPS表征研究

使用程度升温硫化（ＴＰＳ）实验手段研究了一系列Ｃｏ、Ｍｏ和Ｃｏ－Ｍｏ耐硫变换催化剂。结果表明：Ｃｏ３Ｏ４和ＭｏＯ３的硫化还原温度较高;而负载在载体上的活性组分Ｃｏ、Ｍｏ的硫化还的温度大大降低,而且催化剂的硫化还原反应是多步进行的,受Ｏ－Ｓ交换反应控制。     

固体超强酸催化剂改性的研究进展

综述了国内外有关SO42-/MxOy型固体超强酸催化剂在载体、促进剂、贵金属的引入等方面的改性方法。分析了SO42-/MxOy型固体超强酸的催化机理和失活原因。详细说明了载体中引入纳米材料、稀土元素、其他金属元素（Al,V）、交联剂、分子筛等对催化剂活性和稳定性的影响,阐述了通过使用S2O82-代替SO42-、使用WO3、MoO3、PO43等代替SO42-或引入稀土金属离子改变促进剂完成催化剂改性的方法,以及引入贵金属Pt、Pd等在催化剂改性方面的研究进展。最后展望了SO42-/MxOy型固体超强酸催化剂的发展前景。