Ni、Mo双金属催化剂在含氧生物油催化脱氧反应中的应用

为综合利用含氧生物油制备生物柴油,制备了一种新型非硫Ni、Mo双金属催化剂。以硬脂酸转化率为目标,优化了n(Ni)∶n(Mo)、金属负载量及载体类型等影响因素。结果表明,当n(Ni)∶n(Mo)=7∶3、金属负载量为25%、载体m(γ-Al_2O_3)∶m(β-分子筛)为3∶2时,硬脂酸转化率为93. 70%,烷烃的选择性达95. 44%。同时考察了含氧生物油在十二烷和供氢剂四氢萘中的产物分布及组成变化。     

Fe-Mo对二甲苯选择氧化催化剂的制备及其性能

以Fe(NO₃)₃和(NH₄)₆MoO₂₄为原料,采用溶胶-凝胶法制备了不同n(Fe)∶n(Mo)的催化剂,考察了该催化剂对对二甲苯催化氧化合成对苯二甲醛的催化性能。并应用X射线衍射、傅立叶变换红外光谱、紫外漫反射和热分析对催化剂进行了表征。结果表明,Fe对MoO₃改性能明显改善催化剂的活性,提高对苯二甲醛收率,原因是由于Fe₂(MoO₄)₃的生成。当n(Fe)∶n(Mo)=1∶3时,催化剂活性最佳,此时对二甲苯转化率为66.8%,对苯二甲醛选择性和收率分别为37.2%和24.8%。XRD、FT-IR和DRS结果表明,当n(Fe)∶n(Mo)=1∶3时,催化剂中有适量MoO₃存在,其催化活性最好,该催化剂能在高温维持较好的活性稳定性。     

新型流化催化裂化汽油脱硫降烯烃催化剂的研究

以L沸石作为活性组分负载Co-Mo氧化物制备了改性L沸石催化剂,并用X射线衍射、BET测试和红外光谱等方法对催化剂进行表征。以全馏分流化催化裂化(FCC)汽油为原料,临氢条件下,在固定床连续微反应装置上对催化剂脱除硫和烯烃的性能进行了评价,考察了n(Co)∶n(Mo)、金属含量、温度、压力、体积空速和氢油比对催化剂反应性能的影响。结果表明,当催化剂中n(Co)∶n(Mo)=1∶2,w(CoO)=2.5%时,在温度320℃、压力1.5 MPa、体积空速4.0 h-1、V(H2)∶V(FCC汽油)=600∶1的条件下,FCC汽油质量脱硫率达92%左右,烯烃体积饱和率42%左右,汽油抗爆指数损失小于1.0个单位,液体质量收率97%~98%,且催化剂的稳定性好。     

NiMoS/ZSM-5-MCM-41催化剂的制备及其加氢脱硫性能

以十六烷基三甲基溴化铵作为模板剂,将ZSM-5用不同浓度NaOH处理脱硅,并利用重结晶法成功合成了具有较强酸性的ZSM-5-MCM-41复合分子筛[记为ZMC-M(x),M=1.5、2.0、2.5,x=n(SiO_2)/n(Al_2O_3)]。然后,采用浸渍法制备了Mo S2/ZMC和Ni-MoS_2/ZMC催化剂。考察了不同浓度NaOH脱硅对复合分子筛ZMC结构和性质的影响。同时以噻吩为模型化合物,考察了ZMC的硅铝比、NiMo双金属硫化物对噻吩加氢脱硫的影响。结果表明,随着NaOH浓度的增加,复合分子筛ZMC会生成更多的介孔相,但是过高浓度NaOH处理后会破坏ZSM-5的结构,确定了最佳NaOH处理浓度为2.0 mol/L。随着ZMC硅铝比的增加,催化剂加氢脱硫活性提高,并且复合分子筛负载Ni Mo双金属硫化物的加氢脱硫性能优于复合分子筛负载MoS_2。在H2压力3 MPa、温度280℃、40 mL(1 mg/L)噻吩/十四烷溶液中,0.1 g的20%MoS2/ZMC-2.0(70)和20%Ni-MoS2/ZMC-2.0(70)[m(Mo)∶m(ZMC)=1∶5,n(Ni)∶n(Mo)=1∶1]催化剂对噻吩的转化率分别达到84.1%和95.2%。     

极低负载量活性组分催化剂对丙烷选择氧化性能的影响

以SiO_2为载体,采用等体积浸渍法制备了极低负载量活性组分氧化物催化剂,并评价对丙烷选择氧化性能。结果表明,在对丙烷分子氧选择氧化催化反应中,具有相对稳定半充满电子的表面离子结构的催化剂对生成醛类含氧化合物选择性较高。碱金属钾的修饰作用使含氧化合物选择性有较大提高。     

硫酸氢钠催化合成乙二醇单甲醚乙酸酯

将硫酸氢钠作为由乙二醇单甲醚和乙酸酯化合成乙二醇单甲醚乙酸酯的催化剂。研究了反应的影响因素和催化剂重复使用性能。当n(乙二醇单甲醚)∶n(乙酸)∶n(硫酸氢钠)＝1∶1.75∶0.003 62、苯为带水剂、回流分水60 min时,酯收率达90.0%。     

以对甲苯磺酸为主催化剂合成三酚基乙烷的研究

为了提高标题化合物THPE的产率、简化操作过程,以苯酚和乙酰丙酮为原料,选用对甲苯磺酸和3-巯基丙酸作催化剂,合成了标题化合物;采用红外光谱分析、1HNMR和液相色谱对标题化合物的结构和纯度进行了表征。通过单因素试验,考察了原料配比、主催化剂用量、助催化剂用量、反应温度和反应时间对产率的影响,得出标题化合物的最佳合成工艺为:n(苯酚)∶n(乙酰丙酮)=9∶1;m(对甲苯磺酸)∶m(乙酰丙酮)=1∶1;m(3-巯基丙酸)∶m(乙酰丙酮)=1∶7;反应温度55℃;反应时间24 h;THPE粗产品产率稳定在78%以上。同时对其纯化处理进行了研究,1次CH2Cl2和4次乙醇/水提纯后产品的纯度达到了99.86%。     

磷钨杂多酸催化乙醇和乙酸酯化反应的研究

以多孔钛片为支撑体,制备了磷钨杂多化合物薄膜化催化剂。在膜催化器上,考察了薄膜化催化剂对乙醇和乙酸合成乙酸乙酯的催化性能。结果表明,薄膜化催化剂显著提高了催化活性;当n(乙醇)∶n(乙酸)=1.5∶1,原料流量2.55mL/h;在反应温度为110℃时,乙酸乙酯产率可达97%,且薄膜催化剂的处理很方便,不污染环境。     

苯胺、尿素、甲醇一步法合成苯氨基甲酸甲酯

用苯胺、尿素和甲醇一步法合成了苯氨基甲酸甲酯(MPC)。考察了不同类型催化剂对MPC生成的影响。对性能最好的HY分子筛催化剂着重考察了催化剂用量,反应温度,反应时间和原料摩尔比对反应的影响。结果表明,n(C6H5NH2)∶n(NH2CONH2)∶n(CH3OH)=1∶5∶15,反应温度453 K,反应时间5 h为适宜工艺条件。在该工艺条件下,苯胺转化率和苯氨基甲酸甲酯选择性分别达到90.5%和73.5%。     

磷钨钼杂多酸催化氧化环己醇清洁合成己二酸

以自制H3PW6Mo6O40·nH2O为催化剂,在无有机溶剂、相转移催化剂的情况下,用过氧化氢氧化环己醇合成己二酸。探讨了催化剂用量、过氧化氢用量、反应时间、反应温度对反应的影响。在优化条件下,即n(环己醇)∶n(磷钼钨杂多酸)∶n(过氧化氢)=100∶0.15∶500,在120℃反应8h,己二酸的分离收率达82%。     

Potassium-modified molybdenum-containing SBA-15 catalysts for highly efficient production of acetaldehyde and ethylene by the selective oxidation of ethane

Mo-incorporated SBA-15 (Mo-SBA-15) catalysts with different Mo:Si molar ratios were synthesized by a direct hydrothermal method, and SBA-15-supported Mo catalysts (Mo/SBA-15 and K-Mo/SBA-15) were prepared by an incipient-wetness impregnation method. The structures of the catalysts were characterized by means of N₂ adsorption–desorption, XRD, TEM, FT-IR, and UV-Raman, and their catalytic performance for the oxidation of ethane was tested. Turnover frequency and product selectivity are strongly dependent on the molybdenum content and catalyst preparation method. Furthermore, the addition of potassium promotes the formation of isolated tetra-coordination molybdenum species and potassium molybdate. The K/Mo-SBA-15 catalysts possess much higher catalytic selectivity to acetaldehyde in the selective oxidation of ethane than the supported molybdenum catalysts (Mo/SBA-15 or K-Mo/SBA-15). The highest selectivity of CH₃CHO + C₂H₄ 68.3% is obtained over the K/Mo-SBA-15 catalyst. Analysis of kinetic results supports the conclusion that ethane oxidation is the first-order reaction and ethane activation may be the rate-determining step for the oxidation of ethane. Ethylene is a possible intermediate for acetaldehyde formation.     

Hydrodesulfurization over intrazeolite molybdenum nitride clusters prepared by using hexacarbonyl molybdenum as a precursor

Metal nitride catalysts have received extensive attention because of their potential high performance for hydrodesulfurization (HDS). In the present study, highly dispersed Mo nitride clusters having a composition of Mo₂N are synthesized in zeolite pores by means of a CVD method using Mo(CO)₆ as a precursor. The catalytic properties of the molybdenum nitride catalysts for the HDS of thiophene are compared with that of an intrazeolite molybdenum sulfide catalyst. The molybdenum nitride catalyst shows a more stable thiophene HDS activity than the molybdenum sulfide catalyst. Molybdenum nitride clusters are only partially sulfided even after a prolonged HDS reaction.     

Dibenzothiophene hydrodesulfurization over MoP/SiO<Subscript>2</Subscript> catalyst prepared with sol-gel method

Silica-supported molybdenum phosphide, MoP/SiO₂ catalysts with different Mo weight loadings were prepared by temperature programmed reduction of the oxidic catalyst precursors, which were prepared via sol-gel technique using ethyl silicate-40 as silica source. Samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), BET surface area measurements, and their catalytic activity in hydrodesulfurization (HDS) was tested with dibenzothiophene (DBT) as model compound. XRD analysis revealed the amorphous nature of the catalyst up to 10 wt% Mo loading and the formation of crystalline MoP phase on amorphous silica support with higher Mo loading. BET surface area showed high surface area for catalysts prepared by sol-gel technique with lower Mo content, and the surface area decreased with increasing in Mo loading. The HDS results showed that prepared MoP/SiO₂ exhibited high HDS activity and stability toward the catalytic test. Among the series of catalysts prepared, MoP/SiO₂ containing 20 wt% Mo was found to be the most active catalyst. And the effects of reaction temperature and hydrogen pressure on conversion and product selectivity were investigated.     

Molybdenum-titanium oxide catalysts: the influence of the preparation conditions on their activity for the selective catalytic reduction of NO by NH3

MoO₃/TiO₂ catalysts of varying molybdenum content were prepared at various pHs and concentrations of the impregnating solution using the equilibrium deposition filtration (EDF) method. Moreover, a catalyst corresponding to the EDF one with the maximum Mo loading was prepared using the conventional non-dry impregnation (NDI) method. The above catalysts were characterized using X-ray powder analysis, diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy, and tested for the selective catalytic reduction of NO by NH₃ in the temperature range 250–450 °C. It was found that the application of EDF results in an improved MoO₃/TiO₂ catalyst exhibiting higher activity than the corresponding sample prepared by the conventional NDI method. The catalytic activity correlates well with the concentration of the Mo species strongly interacting with the anatase surface. The concentration of the above species is maximized when the EDF method is employed to prepare the catalysts. This is especially, so when low pH and Mo concentration of impregnating solution are used.     

钼基催化剂在烯烃液相环氧化反应中的应用研究进展

介绍了钼络合物催化剂、固载化的钼络合物催化剂及MoO₃基的固体钼催化剂在烯烃液相环氧化反应中的应用。以有机过氧化物为氧化剂时,不同的钼基催化剂均表现出很好的催化性能,其中络合物中的配体对其催化性能有很大影响,并且可以通过引入手性配体实现对烯烃的不对称环氧化,而固体钼催化剂的性能则与载体上钼物种的种类密切相关。但绝大多数钼催化剂对H₂O₂参与的环氧化反应没有活性,开发对H₂O₂有催化活性的钼基催化剂是一个重要的研究方向。     

Alumina Supported Co–K–Mo Based Catalytic Material for Diesel Soot Oxidation

Alumina supported Co–K–Mo based mixed metal oxide type catalytic materials have been prepared by co-impregnation. These catalysts show excellent activity for carbon as well as diesel soot oxidation, which could be due to the redox properties of Mo and Co as well as to a synergistic effect of molybdenum, cobalt, and K contents. The catalyst containing 5 wt% molybdenum shows a lowering of carbon oxidation by about 190 °C under loose contact conditions as compared to the non-catalyzed reaction, as well as to bare alumina. Characterization studies suggest a composite nature of these materials, while thermal stability investigations confirm the stable nature. The selected catalyst has been studied by XPS, however, it is difficult to conclude which are the important factors contributing to the catalytic activity. It appears to be a synergistic effect of Co, K, and Mo components as these catalysts show much improved activity as compared to the individual components in supported and unsupported forms.     

碳化钼催化剂的制备及噻吩加氢脱硫性能

以MoO₃为前躯体,CH₄/H₂为还原碳化气,采用自制的程序升温还原碳化反应装置制备出Mo₂C催化剂,并用XRD、BET进行表征.借助原位TG-DTA方法研究了MoO₃在CH₄/H₂气氛中的还原碳化历程和适宜的还原碳化温度.以噻吩/环己烷溶液为模型反应物,采用高压微反-色谱实验装置考察了制备的碳化钼催化剂的噻吩加氢脱硫反应性能.结果表明：程序升温条件下的局部规整反应可提高催化剂的比表面积,且制备的碳化钼催化剂具有较高的噻吩加氢脱硫反应活性,在体积分数为5%的噻吩/环己烷溶液中,反应压力为3.0 MPa,空速为6 h^-1,H₂/原料液体积比500∶1的反应条件下, 370℃时的噻吩转化率达到98%以上,明显高于相应的硫化钼催化剂.还原碳化终温的提高,导致碳化钼催化剂比表面积的减少和表面积炭的增多,进而使其加氢脱硫反应活性降低.MoO₃在CH₄/H₂气氛中的还原碳化历程应为MoO₃→MoO₂→MoO_xC_y→Mo₂C,实验确定的适宜还原碳化温度为675℃.     

负载型MoO3/β分子筛催化剂的丙烷氧化脱氢性能

以β分子筛为载体,通过浸渍法负载钼制备MoO₃/β分子筛催化剂,对其进行XRD、FT-IR、BET和NH₃-TPD物化性能表征,考察其对丙烷氧化脱氢制丙烯的催化性能。结果表明,样品具有活性组分MoO₃存在,也有不同酸性能的活性位存在。负载量对催化剂的表面积和孔径有影响。单纯β分子筛载体有催化活性,不同钼负载量对催化性能有影响,负载钼质量分数为20%时,转化率达到极大值。     

A study of Mo-modified Pd/MWCNT catalysts for ethanol oxidation in the alkaline solution

The effect of the modification of Pd-based electrocatalysts by molybdenum on the catalytic performance toward ethanol oxidation in the alkaline solution is investigated. The results indicate that the molybdenum oxide/hydroxide assists in the uniform distribution of Pd nanoparticles on the surface of the carbon support. The catalytic performance of the Mo-modified Pd/MWCNT catalyst is largely dependent on the temperature at which the molybdenum oxide/hydroxide is heat-treated. The catalyst prepared from the molybdenum oxide/hydroxide heat-treated at 350 °C has the highest catalytic activity and the best poison resistance. X-ray photoelectron spectroscopy results reveal that there is an interaction between Pd and Mo in Mo-modified Pd/MWCNT catalysts. The moderately dehydrated and oxidized molybdenum oxide/hydroxide has the strongest effect on promoting the catalytic activity and the poison resistance of Pd-based nanocatalysts for ethanol oxidation.     

Cumene hydrocracking and thiophene HDS on niobia-supported Ni, Mo and Ni–Mo catalysts

Results are reported on the XPS characterization and catalytic activity in cumene hydrocracking (2.8 MPa, 623 K) and thiophene HDS (2.8 MPa, 523–573 K) of sulfided Ni, Mo and Ni–Mo catalysts supported on alumina and on pure and phosphated niobia. From the XPS results, evidence was obtained for the formation of a surface niobium sulfide with stoichiometry close to NbS₂ during catalyst sulfidation. Sintering of supported nickel during sulfidation occurred to a much smaller extent with the niobia-supported catalysts than with the alumina-supported ones. The dispersion of alumina-supported molybdenum was little influenced by sulfidation, whereas, with the niobia supports, the molybdenum surface concentration increased with sulfidation. With the alumina support, the Ni–Mo combination caused the dispersion of the sulfided nickel to be improved, possibly due to formation of a NiMoS phase. This was not observed with the niobia-supported catalysts.

Reasonable linear correlations were also found between the intrinsic activity for cumene hydrocracking and the amount of sulfided niobium in the catalysts, but the catalysts supported on phosphated niobia had a higher intrinsic activity than the ones supported on pure niobia. In thiophene HDS, the activity of the niobia-supported nickel catalysts was much larger than the activity of the alumina-supported ones. The activity of the niobia-supported molybdenum catalysts was smaller than that of the alumina-supported catalyst. With the bimetallic catalysts, little or no synergy was observed with the niobia-supported catalysts, in sharp contrast with the alumina case.