HxCu1.2PAs0.6Mo12Oy杂多化合物膜催化剂与异丁烯选择氧化

以多孔钛片为支撑体,将组成为HxCu1.2 PAs0.6Mo12Oy的杂多化合物与具有氧溢流效应的氧化物Sb2O4及Ce0.5Zr0.5O2分别制成催化膜,在特制的膜催化反应器中进行异丁烯选择氧化反应. 结果表明,杂多化合物-Sb2O4催化膜与杂多化合物-Ce0.5Zr0.5O2催化膜均具有较高的催化活性;在适宜的条件下,甲基丙烯酸收率最高可达26.3%、甲基丙烯醛收率可达22.4%,液体产物(即可用产物,包括甲基丙烯酸、甲基丙烯醛、乙酸和丙酮) 总收率可达67.4%.     

甲醇选择氧化制甲酸甲酯双功能催化剂的研究进展

甲醇是重要的化工基础原料,在双功能催化剂的作用下,甲醇选择氧化可以制取高附加值的甲酸甲酯下游产品.本文对近年来甲醇选择氧化制甲酸甲酯的催化剂体系、反应工艺、反应机理等方面的研究进展进行了归纳、总结和评述,特别是贵金属及其合金催化剂表面活性氧物种对甲醇的选择氧化机理、金属结构和纳米颗粒尺寸与O2的吸附解离关系、金属间电子...     

杂多化合物复合催化膜的研究

以多孔钛片为支撑体，将组成为HxCu1.2PAs0.6Mo12Oy的杂多化合物与具有氧溢流效应的氧化物Sb2O4制成复合催化膜，在特制的膜催化器中进行异丁烯选择氧化反应，结果表明，杂多化合物-Sb2O4复合催化膜具有较高的催化活性。在适宜的条件下，甲基丙烯酸收率可达26.3%。甲基丙烯醛收率可达22.4%。     

异丁烯两段催化氧化制甲基丙烯酸催化剂的研究 Ⅱ．甲基丙烯醛气相氧化制甲基丙烯酸的杂多酸盐催化剂的研究

本文报道用于甲基丙烯醛（ＭＡＬ）选择氧化制甲基丙烯酸（ＭＡＡ）的ＰＭｏＶ杂多酸盐催化剂的研究结果。ＩＲ和ＸＲＤ考察结果表明，本文所研究的催化剂均具有稳定的Ｋｅｇｇｉｎ结构，催化剂物相组成为Ｈ（４－２ｙ－２）ＰＯ４（ＭｏＯ３）（１２－ｘ）（ＶＯ３）ｘＣＵｙＣｓｚ。在３００℃，原料气组成ＭＡＬ：Ｈ２Ｏ：Ｏ２：Ｎ２＝１：１０：３：３２．体积空速１２００ｈ（－１）的条件下，最佳催化剂的ＭＡＬ转化率为９４．１％，ＭＡＡ选择性达８８．７％。     

杂多化合物复合催化膜研究

以多孔钛片为支撑体 ,将组成为HxCu1.2 PAs0 .6 Mo12 Oy 的杂多化合物与具有氧溢流效应的氧化物Sb2 O4 制成复合催化膜 ,在特制的膜催化器中进行异丁烯选择氧化反应。结果表明 ,杂多化合物—Sb2 O4 复合催化膜具有较高的催化活性 ,在适宜的条件下 ,甲基丙烯酸收率可达 2 6.3 % ,甲基丙烯醛收率可达 2 2 .4%。     

负载杂多化合物催化酯类反应研究进展

综述了杂多化合物催化剂催化酯类反应在国内外的研究和应用情况。杂多化合物由于具有准液相和超强酸性的特征,广泛用于各种酯类反应。杂多酸作为均相催化剂催化酯类反应具有很高的活性和选择性,但存在反应产物和催化剂分离问题。采用杂多酸盐及以活性炭、SiO₂、TiO₂和MCM-41等负载的杂多化合物多相催化酯类,催化剂不仅具有很高反应活性和选择性,同时易于同产物分离,克服了均相催化的缺点。     

杂多化合物催化剂在精细化工合成中的应用

本文综术了杂多化合物作为酸催化剂，催化烷基化和去烷基化反应、缩聚反应、水合和失水、酯化和醚化反应；以及作为氧化催化剂，在烯烃、芳烃、酚的氧化和环氧化反应中的应用。表面杂多化合物作为催化剂在合成精细化学中有广泛的应用价值。     

异丁烯两段催化氧化制甲基丙烯酸催化剂的研究* Ⅱ.甲基丙烯醛气相氧化制甲基丙烯酸的杂多酸盐催化剂的研究

本文报道用于甲基丙烯醛(MAL)选择氧化制甲基丙烯酸(MAA)的PMoV杂多酸盐催化剂的研究结果。IR和XRD考察结果表明,本文所研究的催化剂均具有稳定的Keggin结构,催化剂物相组成为H_4-2y-zPO₄(MO₃)_12-x(VO₃)_xCu_yCs_z。在300 ℃,原料气组成MAL:H₂O:O₂:N₂=1:10:3:32,体积空速1 200 h^-1的条件下,最佳催化剂的MAL转化率为94.1%,选择性达88.7%。     

硒钒杂多化合物在有机合成中的催化作用

有关硒钒杂多化合物的应用很少见诸报道。本文以催化合成乙酸乙酯和乙酸两个实验为基础 ,对硒 -钒类杂多化合物 (NH4 ) 7[HSe4 V1 0 O37]· 9H2 O的催化性能进行了初步的探讨和研究。实验结果显示其催化性能优于传统催化剂。     

Pt系异丁烷脱氢催化剂研究进展

综述了Pt系异丁烷脱氢的研究状况,探讨了铂系催化剂的活性中心,重点总结了载体、助剂、失活这几方面对铂系催化剂的反应性能的影响,并对铂系催化剂的研究前景进行了展望.     

Transition metal-doped heteropoly catalysts for the selective oxidation of methacrolein to methacrylic acid

Heteropoly compounds with the general formula Cs₁M_0.5^x+H_3?0.5xP_1.2Mo₁₁VO₄₀ (M= Fe, Co, Ni, Cu or Zn) and Cs₁Cu_yH_3?2yP_1.2Mo₁₁VO₄₀ (y = 0.1, 0.3 or 0.7) were synthesized and then used as catalysts for the selective oxidation of methacrolein to methacrylic acid. The effects of the transition metals on the structure and activity of the catalysts were investigated. FTIR spectra showed that the transition metal-doped catalysts maintained the Keggin structure of the undoped catalysts. X-ray diffraction results indicated that before calcination, the catalysts doped with Fe and Cu had cubic secondary structures, while the catalysts doped with Co, Ni or Zn had both triclinic and cubic phases and the Co-doped catalyst had the highest content of the triclinic form. Thermal treatment can decrease the content of the triclinic phase. NH₃ temperature-programmed desorption and H₂ temperature-programmed reduction results showed that the transition metals changed the acid and redox properties of the catalysts. The addition of Fe or Cu had positive effects on the activities of the catalyst which is due to the improvement of the electron transfer between the Fe or Cu and the Mo. The effects of the copper content on structure and catalytic activity were also investigated. The Cs₁Cu_0.3H₂P_1.2Mo₁₁VO₄₀ catalyst had the best performance for the selective oxidation of methacrolein to methacrylic acid.     

Thermal stability and catalytic properties of the Wells-Dawson K6P2W18O62·10H2O heteropoly compound in the oxidative dehydrogenation of isobutane to isobutene

The thermal stability of the Wells-Dawson heteropoly compound K₆P₂W₁₈O₆₂·10H₂ was examined under both reducing and oxidizing conditions, and its structural and morphological evolution was characterized by several complementary solid state techniques. It is shown that the primary structure of this compound remains intact up to 770 K, while at higher temperature structural changes and rearrangements are observed. These modifications depend considerably on the treatment conditions and catalyst composition. Under oxidizing conditions the Wells-Dawson compound rearranges with formation of a mixed phase containing the Keggin-type unit K₃PW₁₂O₄₀ and the hexatungstate K₂W₆O₁₉. Furthermore, the catalytic activity in the oxidation of isobutane is affected considerably by these changes. The best catalytic performance was shown by the rearranged Wells-Dawson compound.     

异丁烷脱氢Pt系催化剂研究进展

介绍异丁烷脱氢制备异丁烯Pt系催化剂的研究进展,表明催化剂的活性中心、载体和助剂对异丁烷脱氢反应性能影响较大。催化剂活性中心的积炭覆盖和烧结是催化剂失活的直接原因;载体的酸性有助于调变积炭的形成速率,而活性中心与助剂的交互作用可促使积炭的表面迁移;活性中心与载体的交互作用有利于减少活性中心的烧结。     

丙烷选择氧化金属氧化物催化剂的研究进展

综述了多组分金属氧化物催化剂对非均相选择氧化反应的一般特性，包括酸特性和氧物种的性质及在催化反应中结构／晶相状态的变化。并对丙烷选择氧化的机理及Mo—V—Sb(Te)—Nb—O多组分混合金属氧化物的晶相结构及性能进行了总结。     

异丁烷催化脱氢研究进展

异丁烷催化脱氢产物异丁烯可用于制备甲基叔丁基醚、丁基橡胶和聚异丁烯，也可用于合成甲基丙烯酸酯和异戊二烯等各种有机原料和精细化学品。从异丁烷催化脱氢反应机理、现有工艺和催化剂研究等方面综述了异丁烷催化脱氢的研究进展。催化剂研究主要包括催化剂的制备方法、制备条件、助催化剂的作用以及评价条件。     

肉桂醛选择性加氢Co-Fe/硅藻土催化剂稳定性考察

通过肉桂醛在高压微反固定床上24 h的催化加氢反应,考察了肉桂醛选择加氢的催化剂Co-Fe/硅藻土稳定性。结果表明,肉桂醛选择加氢催化剂Co-Fe/硅藻土在反应初期存在反应的诱导期,诱导期后,肉桂醛转化率70%,肉桂醇选择性80%,肉桂醇收率可达60%以上,且催化性能趋于平稳,表现出良好的催化性能和稳定性。利用XRD、SEM、TG-DSC对反应前后催化剂结构进行表征,发现催化剂经24 h反应,结构不变,表面颗粒分布更细化,无积炭迹象。     

纳米金催化剂在CO低温氧化和选择性氧化中的研究进展

介绍了纳米金催化剂在CO低温氧化和丙烯直接环氧化反应中的研究进展。在CO低温氧化反应中,催化剂的活性相和载体都具有明显的尺寸效应,纳米金颗粒和载体之间的相互作用主要表现载体不仅可以改变纳米金颗粒的大小和形状,而且也影响了氧的活化,从而提高反应活性;在丙烯直接环氧化反应中,由H2和O2在金颗粒表面反应生成的过氧化物种是反应中间体;在选择性氧化和选择性加氢反应中,金催化剂表现出优良的活性和稳定性。     

杂多酸及其负载型催化剂的研究进展

介绍了杂多酸的基本特性及其负载型催化剂的研究进展,包括不同类型的催化剂载体。     

Combined Effects of Sb-Doping and of Preparation via Lacunary Precursor for P/Mo-Based, Keggin-Type Polyoxometalates, Catalysts for the Selective Oxidation of Isobutane to Methacrylic Acid

Catalysts for the selective oxidation of isobutane to methacrylic acid, based on ammonium salts of phosphorus/molybdenum Keggin-type polyoxometalates, were prepared by precipitation of a lacunary precursor at pH 4.0, and by calcination of the precipitate at 350 °C in air. The thermal treatment led to the transformation of the lacunary polyoxometalate into (NH₄)₃PMo₁₂ O₄₀. This procedure yielded a catalyst that was active, but poorly selective, from the beginning of its reaction time, since the active sites were generated during the calcination, and thus during the transformation of the lacunary precursor into the Keggin compound. Nevertheless, for the reaction under isobutane-rich conditions, the catalyst exhibited an initial period during which the progressive reduction of the polyoxometalate led to an improvement of the selectivity to methacrylic acid. An alternative method to develop a partially reduced compound was by preparation of a Sb³⁺-doped polyoxometalate. A solid-state redox reaction between Sb³⁺ and Mo⁶⁺ occurred in the Keggin framework during the calcination of the precursor. With this procedure, a catalyst was obtained, which did not require the preliminary equilibration, and which therefore was active and selective from the beginning of its reaction time. Furthermore, the catalyst was found to be surprisingly very active under isobutane-lean conditions.     

新型异丁烷脱氢催化剂性能

对异丁烷脱氢催化剂YBD-101和国外某催化剂L进行性能比较。采用XRD和BET研究催化剂的物相结构和比表面积,固定床反应器考察两种催化剂的异丁烷脱氢催化活性和产物选择性。结果表明,催化剂YBD-101较催化剂L具有Cr2O3颗粒细小和比表面积大等特点。在反应温度(500~620)℃和空速(1.0~2.0)h-1条件下,催化剂YBD-101的异丁烷转化率高于催化剂L8个百分点,产物选择性高于催化剂L 3个百分点。催化剂YBD-101的活性稳定性优于催化剂L,再生周期明显延长,具有较好的经济效益和社会效益。