不同MoO_3质量分数MoO_3-ZrO_2的合成表征及正己烷异构化性能

水热法合成了不同Mo O_3质量分数的MoO_3-Zr O_2,利用N2吸附-脱附、X射线衍射、红外光谱和扫描电镜手段对MoO_3-Zr O_2进行分析。MoO_3-Zr O_2的正己烷异构化实验在固定床反应器上进行。结果表明:适量MoO_3的添加促进四方晶相ZrO_2的生成,使MoO_3-Zr O_2的比表面积增大。MoO_3-Zr O_2中含MoO_3质量分数为20%时,MoO_3在ZrO_2表面高度分散,其正己烷的转化率和异构产物的收率分别达到48.6%和34.1%。     

CoO/MoO_3/Al_2O_3复合物催化H_2O_2氧化模型柴油脱硫

以γ-Al_2O_3为载体,通过等体积浸渍法,制备了CoO/MoO_3/Al_2O_3催化剂。采用N_2吸附-脱附、X射线衍射(XRD)对CoO/MoO_3/Al_2O_3进行表征分析。以二苯并噻吩(DBT)、4-甲基二苯并噻吩(4-MDBT)为模型柴油的有机硫化物,30%的过氧化氢为氧化剂,考察了CoO/MoO_3/Al_2O_3催化剂的催化性能,并且研究了不同Mo/Co摩尔比、催化剂焙烧温度、投加量、反应时间及温度对氧化脱硫的影响。实验结果表明:H_2O_2-CoO/MoO_3/Al_2O_3构成的氧化体系能有效氧化模型柴油中的有机硫化物,DBT和4-MDBT脱硫率分别达到98.8%、93.4%;Mo/Co摩尔比、催化剂焙烧温度、投加量、反应时间及温度对有机硫化物的氧化脱硫均有影响;CoO/MoO_3/Al_2O_3催化剂经过再生处理后可重复使用,具有良好的稳定性。     

MoO_3-CeO-Co_3O_4催化剂CO催化氧化及耐硫性能

采用共沉淀法和浸渍法联用制备不同Mo质量分数的x MoO_3-6CeO-Co_3O_4催化剂,测试催化剂催化氧化CO效率及其耐硫性能,并对催化剂进行BET、SEM、FT-IR和H2-TPR等表征。结果表明,MoO_3的添加可以提高催化剂低温活性,5.61MoO_3-6CeO-Co_3O_4催化剂低温活性最佳,40℃时CO去除率达98%,耐硫性能达90 min。     

PS乳液对MoO_3-ZrO_2结构及异构化性能的影响

以十六烷基三甲基溴化铵(CTAB)为模板,CTAB与聚苯乙烯(PS)乳液混合物为复合模板剂,采用水热法合成了MoO_3-ZrO_2复合氧化物。利用XRD、SEM、BET和Py-IR等手段对其进行表征,在固定床反应装置上进行MoO_3-ZrO_2复合氧化物催化正己烷异构化活性评价实验。考察了PS乳液对MoO_3-ZrO_2复合氧化物晶相、孔结构、酸性和异构化性能的影响。结果表明,模板剂的组成变化不会改变MoO_3-ZrO_2的晶相结构,添加适量的PS乳液可以形成大孔-介孔的多级孔结构,有利于正己烷的异构化反应。     

Fe_2(MoO_4)_3/MoO_3纳米棒催化剂的制备及应用

通过水热法合成具有一维纳米结构的MoO_3纳米棒,利用MoO_3纳米棒的尺寸约束作用,以MoO_3纳米棒和铁盐为原料,采用浸渍法及高温焙烧下发生的固相反应,在经典Kirkendall效应影响下合成Fe_2(MoO_4)_3/MoO_3纳米棒催化剂。以空气氧化甲醇制甲醛为目标反应,评价其催化性能。结果表明,以Mo与Fe原子比2.2∶1制备的Fe_2(MoO_4)_3/MoO_3纳米棒催化剂催化性能较佳,甲醇转化率≥99.5%,甲醛选择性≥96.0%。     

MoP/SiO_2-TiO2-ZrO_2催化剂加氢脱硫工艺条件考察

采用共沉淀法制备了SiO_2-TiO_2-ZrO_2三元复合氧化物载体,用浸渍法负载活性组分MoP制备MoP/SiO_2-TiO_2-ZrO_2催化剂。在固定床微反应器上,采用正交实验研究了反应温度、空速、氢油体积比和氢分压对催化剂噻吩加氢脱硫性能的影响,并对劣质催化裂化(FCC)柴油的脱硫性能进行了考察。结果表明,催化剂最佳加氢脱硫条件为:反应温度380℃,空速2 h^(-1),氢油体积比500,氢分压4 MPa,此条件下,FCC柴油脱硫率达97.50%。     

Fe掺杂对Pt-Sn-K/γ-Al_2O_3异丁烷脱氢催化剂性能的影响

采用共沉淀法制备不同Fe含量的Fe(x)-γ-Al_2O_3复合氧化物载体,并采用真空浸渍法制备了Pt-Sn-K/Fe(x)-γ-Al_2O_3催化剂。对制备的催化剂进行XRD、N_2物理吸附-脱附和NH_3-TPD表征,研究Fe的掺杂对Pt-Sn-K/Fe(x)-γ-Al_2O_3催化剂的结构及其催化异丁烷脱氢反应性能的影响。结果表明,Fe的引入可以改变催化剂的反应活性和产物选择性,当Fe_2O_3掺杂质量分数为4%时,催化剂具有最高的异丁烯收率,50 h的平均收率达到42.9%。     

复合SiO_2-Al_2O_3载体制备及其在柴油深度加氢脱硫中的应用

采用不同方法制备系列复合SiO_2-Al_2O_3载体,以等体积浸渍法负载硝酸镍和钼酸铵溶液制得加氢脱硫催化剂。通过BET、XRD和NH3-TPD对载体进行表征,并以直馏柴油为原料,考察不同载体对催化剂加氢脱硫活性的影响。结果表明,以硅质量分数27%的Si-Al-2载体负载浸渍液制得的催化剂具有较高的加氢脱硫活性,346℃可以将柴油中的硫含量脱除至小于10μg·g-1,加氢脱硫活性较对比剂有很大提高。     

La_2O_3含量对La-Ni/ZrO_2-Al_2O_3催化剂甲烷化性能的影响

采用浸渍法制备了复合氧化物ZrO_2-Al_2O_3,在此基础上采用共浸渍法制备了La-Ni/ZrO_2-Al_2O_3催化剂,考察了催化剂中La2O3含量对催化剂CO甲烷化活性的影响,并利用BET、XRD和TPR对催化剂的物化性能进行了分析。结果表明当La2O3含量为2%~6%(质量分数,下同)时,其在低温和高温时的催化活性均比Ni/ZrO_2-Al_2O_3有一定的提升。另外比较了催化剂4La-Ni/ZrO_2-Al_2O_3和Ni/ZrO_2-Al_2O_3在500℃下连续反应100 h的活性和积碳,结果显示催化剂4La-Ni/ZrO_2-Al_2O_3具有很好的稳定性和优良的抗积碳性能。     

复合添加剂Bi_2O_3–MoO_3–Nb_2O_5对高磁导率Mn–Zn铁氧体微观结构与磁性能的影响

采用高温固相反应制备了Bi_2O_3–MoO_3–Nb_2O_5复合掺杂高磁导率Mn–Zn铁氧体材料,利用扫描电子显微镜、B–H测量仪和阻抗分析仪等对材料结构和性能进行表征,研究了不同含量Mo O3复合添加剂Bi_2O_3–MoO_3–Nb_2O_5对Mn–Zn铁氧体微观结构和磁性能的影响。结果表明:复合添加剂Bi_2O_3–MoO_3–Nb_2O_5中,适量的Mo O3可以有效改善材料的微观结构,提升材料起始磁导率,降低材料比损耗,提升材料饱和磁感应强度,并在Nb2O5=0.020%(质量分数)、Bi2O3=0.015%、Mo O3=0.030%时,材料获得最佳的综合性能:起始磁导率μi=12 457.51,tanδ/μi=3.76×10–6,饱和磁感应强度Bs=0.416 T。     

MoO3／Al2O3催化剂上MoO3的脱附平衡和流失速度

分别测定了在氮，水气氛下ＭｏＯ３自ＭｏＯ３／Ａｌ２Ｏ３催化剂上脱附的平衡数据。发现尽管ＭｏＯ３和Ａｌ２Ｏ３存在着强的化学作用，但气固平衡关系仍然可用Ｆｒｅｕｎｄｌｉｃｈ方程式描述。讨论了钼升华流失速度方程式与Ｆｒｅｕｎｄｌｉｃｈ式的关系。发现在氮水混合气流中，钼的流失总速度可以用它们单独存在时流失速度线性加和来表示。给出了水分压对流失速度影响的级数值。这一综合速度方程式经简化后，可以用于工业过程中钼流失数据的估算。     

Contrasting the Behaviour of MoO3 and MoO2 for the Oxidation of Methanol

The oxidation of methanol has been measured on MoO₃ and MoO₂. The properties of these two materials are interchangeable, depending upon the conditions in which the reaction is run. MoO₃ produces high yields of formaldehyde, but MoO₂ does not, due to the importance of the Mo⁶⁺ state for the selective reaction. However, if the MoO₃ material is run in anaerobic conditions it behaves in a very similar way to MoO₂, due to the presence of Mo⁴⁺ in the surface layers. In complement to this MoO₂ converts to high yield behaviour when run in aerobic conditions, due to the conversion of the material to Mo⁶⁺ at the surface, and, ultimately to MoO₃ in the bulk. In TPD experiments MoO₃ yields formaldehyde, whereas MoO₂ yields CO. In both materials oxygen transport within the lattice becomes appreciable above 300 °C, and the reaction proceeds via the Mars-van Krevelen mechanism.     

MoO3纳米带自组装合成MoS2微球

以MoO3纳米带为前驱体,四丁基溴化铵为表面活性剂,通过水热途径成功合成了MoS2花状微球。用X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)对产物的结构及形貌进行表征和分析。结果表明:MoS2花状微球由带状结构组成,其直径大约为4μm。     

Preparation of MoO3/TiO2 Catalysts with Eggshell and Uniform Mo Distribution by Water-Assisted Spreading of MoO3

MoO₃/TiO₂ catalysts were prepared by reaction of TiO₂ extrudates (140 m²g⁻¹) with a MoO₃/H₂O slurry. The adsorption of molybdena species was strong; sharp, deep eggshell profiles of the Mo concentration were obtained. The hydrodesulfurization activity of saturated catalysts with a uniform Mo distribution (about 10 wt.% MoO₃) was at least the same as that of a sample prepared by conventional impregnation.     

Alkane isomerization on MoO3/ZrO2 catalysts

Molybdenum was used as an alternative to sulfate as promoter of zirconia for alkane isomerization reactions. It has similar effects to sulfate, tungstate and phosphate ions, modifying the physicochemical properties of unpromoted zirconia. Mo‐promoted zirconia catalysts do not show any activity for n‐C₄ isomerization. For n‐C₇ isomerization, the catalytic activity depends on Mo content, crystalline structure of the support and the molybdenum oxospecies present on the surface of the catalysts. This revised version was published online in July 2006 with corrections to the Cover Date.     

Partial oxidation of ethane over K2MoO4/SiO2 and potassium promoted MoO3/SiO2 catalyst

Silica supported K₂MoO₄ and potassium-promoted MoO₃ were used as catalysts for the partial oxidation of ethane in fix-bed continuous-flow reactor at 770–823 K using N₂O as oxidant. The main products of the oxidation reaction were ethylene, acetaldehyde, CO and CO₂. Addition of various compounds of potassium to the MoO₃/SiO₂ greatly enhanced the conversion of ethane and influenced the product distribution. The highest rate and selectivity for acetaldehyde formation was found on a K₂MoO₄/SiO₂ catalyst.     

Study on the reduction of commercial MoO3 with carbon black to prepare MoO2 and Mo2C nanoparticles

A simple method was developed to synthesize MoO₂ and Mo₂C nanoparticles via controlling nucleation and growth in carbothermic reduction of commercial MoO₃ with carbon black. It was found that the appropriate C/MoO₃ molar ratio for preparation of Mo₂C was 2.8, and the carbothermic reduction process followed the sequence: MoO₃ → transport phase (TP) → MoO₂ → Mo₂C. It was revealed that the most crucial issues for controlling number of produced particles of product were migration of Mo source and aid of nucleating agent, which can be achieved by using MoO₃ and carbon black as starting materials. MoO₂ nanosheets with the thickness of 12 nm and lateral size of 60 nm, as well as Mo₂C nanoparticles with particle size of 30 nm were prepared via reduction of MoO₃ with carbon black. However, MoO₂ and Mo₂C produced via reducing MoO₃ by other kinds of carbon sources (activated carbon, graphite) or gas reductants (10% CH₄/H₂, CO) had much larger particle sizes of a few micrometers, which were tens of times than those using MoO₃ and carbon black, due to the too small amount of formed nuclei. The effects of C/MoO₃ molar ratio (0.5-2.8), molybdenum sources and carbon sources on the reaction mechanisms were investigated in detail.     

MoO3/TiO2催化剂的二苯并噻吩加氢脱硫性能

以介孔氧化钛晶须成型材料为载体,通过浸渍法制备不同MoO3负载量的MoO3/TiO2加氢脱硫催化剂. XRD分析表明,介孔氧化钛晶须成型载体为纯锐钛矿相,MoO3负载量为7.2%(w)的催化剂未出现MoO3的衍射峰;BET分析显示,负载7.2%(w) MoO3后,氧化钛晶须成型载体的比表面积和孔容能保持原来的80%以上. 活性评价结果表明,未经预硫化的MoO3/TiO2催化剂直接应用于二苯并噻吩(DBT)加氢脱硫反应时,在温度280~300℃、氢分压2.0 MPa、体积空速4 h-1、H2/油体积比600的条件下,DBT转化率达100%. 将模型溶液中硫含量由400′10-6 g/g降至10′10-6 g/g以下,催化剂表现出较高的活性,且在一定条件下运行1000 h未出现失活迹象.