芳烃加氢金属催化剂抗硫性研究的进展

介绍了在油品芳烃加氢过程中提高镍金属和贵金属催化剂抗硫性研究的进展，对镍催化剂，添加碱金属、碱土金属和其他组分，调节镍金属的还原度及形成镍硼合金等有一定的效果；对贵金属催化剂，铂和钯形成合金，改变金属的颗粒度和载体的酸碱性能及添加碱金属等常被采用。     

Support Effects of Carbon on Pt Catalysts

Experimental evidence for support effect of carbon are summarized for Pt or PtRu catalysts supported by carbon nanotubes and graphene as well as for model catalysts of Pt/HOPG (highly oriented pyrolytic graphite). The electronic modification of Pt catalysts by the support effect is explained by a π–d interaction at the interface between graphitic surface and Pt. The interface interaction is related to non-bonding localized states of carbon, which are observed by scanning tunneling spectroscopy near defects or the doped-nitrogen atom on HOPG. The localized states propagate to a few nanometer regions behaving as acid and basic sites.     

CO Poisoning of Ethylene Hydrogenation over Pt Catalysts: A Comparison of Pt(111) Single Crystal and Pt Nanoparticle Activities

The ethylene hydrogenation reaction was studied on two platinum model catalyst systems in the presence of carbon monoxide to examine poisoning effects. The catalysts were a Pt(111) single crystal and lithographically fabricated platinum nanoparticles deposited on alumina. Gas chromatographic results for Pt(111) show that CO adsorption reduces the turnover rate from 10¹ to 10^-2 molecules/Pt site/s at 413 K, and the activation energy for hydrogenation on the poisoned surface becomes 20.2 ± 0.1 kcal/mol. The activation energy for ethylene hydrogenation over Pt(111) in the absence of CO is 10.8 kcal/mol. The Pt nanoparticle system shows the same rate for the reaction as over Pt(111) in the absence of CO. When CO is adsorbed on the Pt nanoparticle array, the rate of the reaction is reduced from 10² to 10⁰ nmol/s at 413 K. However, the activation energy remains largely unchanged. The Pt nanoparticles show an apparent activation energy for ethylene hydrogenation of 10.2 ± 0.2 kcal/mol in the absence of CO and 11.4 ± 0.6 kcal/mol on the CO-poisoned nanoparticle array. This is the first observation of a significant difference in catalytic behavior between Pt(111) and the Pt nanoparticle arrays. It is proposed that the active sites at the oxide--metal interface are responsible for the difference in activation energies for the hydrogenation reaction over the two model platinum catalysts.     

Ethylene Hydrogenation over Pt/Ga2O3/Al2O3 Catalysts

The effects of gallia addition on the Pt dispersion and the activity for ethylene hydrogenation at 0 °C were studied for Pt-supported catalysts as a function of the reduction temperature (350, 450, and 550 °C). The catalysts contained 0.5 wt.% Pt and were prepared by successive incipient wetness impregnations with Ga(NO₃)₃ and H₂PtCl₆ aqueous solutions. CO and H₂ chemisorption data indicated that, the addition of small amount of Ga₂O₃ caused an increase of the Pt dispersion and a decrease of ethylene conversion. Both of them decreased appreciably when Ga₂O₃ addition was increased, particularly, for the case where β-Ga₂O₃ was used as a support. The increase in reduction temperature magnified the negative effects of the gallia addition on dispersion and activity, although the addition of small amount of gallia improved the resistance to metal sintering. Results were interpreted in terms of the presence of reduced Ga species, which can encapsulate Pt particles.     

Acetylene and Ethylene Hydrogenation on Alumina Supported Pd-Ag Model Catalysts

Adsorption and co-adsorption of ethylene, acetylene and hydrogen on Pd-Ag particles, supported on thin alumina films, have been studied by temperature programmed desorption (TPD). The TPD results show that adding of Ag to Pd suppresses overall hydrogenation activity but increases selectivity towards ethylene, i.e. similar to that observed on real catalysts. The results are rationalized on the basis of a complex interplay between surface and subsurface hydrogen species available in the system, whereby the latter species are the most critical for total hydrogenation of acetylene to ethane.     

Support Effects in Nerol Hydrogenation over Pt/SiO<Subscript>2</Subscript>, Pt/H-Y and Pt/H-MCM-41 Catalysts

Chemoselective hydrogenation of nerol was investigated over Pt/SiO₂, Pt/H-Y and Pt/H-MCM-41 catalysts. The initial total reaction rates decreased in following order: Pt/H-Y > Pt/SiO₂ > Pt/H-MCM-41. Nerol hydrogenation was found to be an apparent structure sensitive reaction. The selectivities to citronellol at 30% conversion of nerol were 65%, 55% and 25% over Pt/SiO₂, Pt/H-MCM-41 and Pt/H-Y, respectively.     

乙二醇稳定的Pt/C催化剂的制备与表征

以乙二醇(EG)兼作溶剂和稳定剂,分别通过NaBH4和EG还原法制备了高度细化与分散的Pt/C催化剂,对其形貌、组成、结构和电化学活性比表面等进行了表征比较,并测试了它们对甲醇与乙醇电催化氧化的活性. 结果表明,2种催化剂中,Pt均为面心立方结构,粒径小且分布窄,在炭黑载体上分散均匀,单位质量Pt对甲醇与乙醇电催化氧化的活性相当;NaBH4还原法所制Pt/C催化剂中Pt0和Pt(220)晶面含量更高,Pt对甲醇与乙醇电催化氧化的峰电流密度分别为0.68与0.67 mA/cm2,分别是EG还原法所制Pt/C催化剂的1.2倍;2种催化剂对甲醇与乙醇电催化氧化的活性均与商品E-TEK催化剂相当.     

Enhanced Sulfur Tolerance of Bimetallic PtPd/Al2O3 Catalysts for Hydrogenation of Tetralin by Addition of Fluorine

A series of mono- and bi-metallic Pt-Pd/Al₂O₃ samples with and without F were studied as aromatic hydrogenation catalysts. The effects of changing the order of impregnation of the Pt precursor and F as well as varying the calcination temperature (300–500 °C) were investigated. Temperature programmed reduction (TPR) results demonstrate the presence of a higher fraction of dispersed metal precursor species left on the surface from the impregnation (PtO _x Cl _y ) on the Pt/Al₂O₃ sample calcined at high temperature. The impregnation of F before the Pt precursor significantly decreases the interaction between the metal and the support. However, this decrease is not observed when F is impregnated after the metal precursor. For the bimetallic Pt-Pd catalysts, the sample prepared adding F before the metal show a higher degree of Pt-Pd interaction than either the parent Pt-Pd/Al₂O₃ catalyst or the one prepared with F added later. TPD of ammonia result show the increase in strong acid sites when F is present. Activity tests for tetralin hydrogenation in the presence of 350 ppm dibenzothiophene indicate a better sulfur tolerance for all F-promoted catalysts, especially Pt-Pd.     

MCM-41负载铂催化剂在甲烷同系聚合中的载体效应

以纯硅和Si/Al比分别为15和10的MCM-41,以及经NH4NO3,HAc和NaNO3的醇溶液交换的MCM-41为载体制得Pt / MCM-41系列催化剂,研究了在甲烷两步同系聚合生成C2     

苯加氢用铂催化剂硫中毒及其再生的研究

以硫化氢为硫源,考察硫对苯加氢用铂催化剂性能的影响及其再生性能。结果表明,对苯加氢反应而言,铂催化剂的活性随原料气中硫含量和运行时间的增加而呈下降趋势。因此,为使苯加氢反应长时间稳定运行,宜将其原料气中的硫控制在2.0×10-6(体积分数)以下,在1.0×10-6(体积分数)以下最佳。铂催化剂的硫中毒是可逆的,去除毒源后,其活性逐渐恢复至正常水平。     

Selective Hydrogenation of Cinnamaldehyde on Pt and Pt-Fe Catalysts Supported on Zeolite P

Abstract  

Pt– and Pt–Fe based catalysts on zeolite P (ZP) support have been prepared and widely characterized by surface area and porosity, XRD, SEM, TEM, TPR, in order to investigate their morphological and microstructural properties. The catalysts have been tested in the selective liquid-phase hydrogenation of cinnamaldehyde. Kinetic tests have shown the beneficial effect of Fe promoter on the catalysts behaviour towards the selective formation of cinnamyl alcohol (85% selectivity to 90% conversion). The ZP supported catalysts have been compared with a catalyst supported on P-zeolitized Fe containing pumice (Z-PM), confirming the role of Fe Lewis acid site in promoting the reactivity of zeolite P-based materials.     

AgRu双金属催化剂在乙二醇选择加氢中的研究

乙醇是化工生产中重要的有机溶剂和生产原料。通过氨蒸法制备新型的AgRu双金属负载Si O2催化剂,采用XRD、BET和TEM等对催化剂进行表征,考察Ru的加入对Ag/Si O2催化剂在乙二醇加氢中催化性能的影响。当在反应温度175℃,压力2 MPa条件下,Ru的加入,对反应活性起到抑制作用,但可促进C-C键的选择加氢。产生这个结果的主要原因可能是由于当Ru的加入,改变了Ag纳米颗粒对C-O键的活化能力。     

工业应用失活与再生加氢催化剂研究

对不同类型工业应用失活和再生后的加氢催化剂研究结果表明,经使用失活及再生后的催化剂在物化性质、孔结构、活性及选择性方面均有不同程度的改变。抚顺石油化工研究院（FRIPP）开发的各种加氢催化剂稳定性强,再生后的催化剂活性能够恢复到较高的水平。     

硫化物对苯部分加氢催化剂的影响

究了原料中硫化合物对苯部分加氢催化剂活性和选择性的影响,得出：苯中硫化合物主要影响催化剂的选择性,在一定范围内对活性影响不太明显。原料苯中硫化合物含量（体积分数）应低于 ５ × １０－６,超过这一范围,选择性开始下降。同时确定了硫化合物中毒为吸附性中毒,具有不可逆性。     

Pt对NiB非晶态合金催化剂对苯加氢性能的影响

A support (denoted AM) was prepared using pseudo-boehmite and mordenite. Ni-B and NiPtB amorphous catalysts were prepared on the support by the impregnation method followed by chemical reduction with a KBH4 solution. And the catalysts were characterized by X-ray diffraction (XRD), environment scanning electron microscope (ESEM), inductively coupled plasma (ICP), H2-temperature programmed reduction (H2-TPR), differential thermal analysis (DTA), and BET. Benzene hydrogenation was used as a probe reaction to evaluate the effect of addition of small quantities of Pt on the NiB/AM catalyst. The results show that Pt can promote the reduction of NiO and the formation of active sites, leading to smaller catalyst particles and better dispersion of active metal particles on the support. The catalytic activity, sulfur resistance and thermal stability were remarkably improved by Pt doping of the NiB/AM catalyst.     

Effective and Reusable Pt Catalysts Supported on Periodic Mesoporous Resols for Chiral Hydrogenation

Platinum nanoparticles supported on periodic mesoporous resols by simple impregnation serve as effective, robust and remarkably reusable catalysts after chirally modified with cinchonidine for the asymmetric hydrogenation of ethyl pyruvate, affording up to 62% enantiomeric excess (ee) and a constant activity after 25th re-use. They can also catalyze the reaction in an environmentally benign manner by using water as a solvent.     

Comparison of Ethylene Glycol Steam Reforming Over Pt and NiPt Catalysts on Various Supports

Steam reforming of ethylene glycol (EG) was studied on Pt and NiPt catalysts supported on γ-Al₂O₃, TiO₂, and carbon. On all supports bimetallic NiPt catalysts show higher activity for H₂ production than the corresponding Pt catalysts as predicted from model surface science studies. The kinetic trends are similar for all catalysts (Pt and NiPt) with the H₂ production rate being zero-order and fractional order with respect to water and ethylene glycol, respectively. Slight differences in selectivity to minor products are observed depending both on active metal and support. On γ-Al₂O₃, NiPt shows higher H₂ and less alkane formation than Pt. TiO₂ supported catalysts show increased water-gas shift activity but also increased selectivity to alkane precursors. NiPt/C is identified as an active and selective catalyst for EG reforming.     

Hydrogenation of Citral using Monometallic Pt and Bimetallic Pt‐Ru Catalysts on a Mesoporous Support in Supercritical Carbon Dioxide Medium

Supercritical carbon dioxide was shown to be a suitable reaction medium for the highly efficient hydrogenation of citral using monometallic Pt and bimetallic Pt‐Ru supported on a mesoporous material, MCM‐48, as catalyst. A remarkable change in the product distribution was observed after the addition of Ru to the monometallic Pt catalyst in supercritical carbon dioxide. The monometallic Pt catalyst was found to be highly selective to the unsaturated alcohol (geraniol+nerol) at a temperature of 323 K within 2 h whereas the bimetallic catalyst becomes selective to the partially saturated aldehyde (citronellal) under the same reaction conditions. Phase behavior plays an important role in the product distribution. Highest conversion and high selectivity to citronellal were achieved in the homogeneous phase for the Pt‐Ru catalyst while on the other hand the unsaturated alcohol (geraniol+nerol) was produced in the heterogeneous phase for the monometallic Pt catalyst. An XPS study offers strong evidence of the electronic modification of Pt after the addition of Ru in the bimetallic catalyst. The change in product distribution on the Pt‐Ru bimetallic catalyst may be explained by the appreciable interaction between the medium and the metal particles promoted by the presence of metallic Ru.