双氧水生产用钯催化剂的再生复活研究

介绍了双氧水的性质、用途及应用前景;通过小试,对某双氧水生产装置失活钯催化剂进行了再生试验研究。     

浅析双氧水生产用钯催化剂的合理使用

阐述就目前国内采用蒽醌法固定床钯催化剂生产双氧水的使用现状、存在问题及如何正确使用。     

蒽醌法双氧水生产中钯催化剂的使用

介绍了蒽醌法双氧水生产工艺,着重对催化剂的装填、活化、维护、再生过程进行了阐述.提出了优化催化剂使用的措施.     

葸醌法双氧水生产中钯催化剂的使用

介绍了蒽醌法双氧水生产工艺，着重对催化剂的装填、活化、维护、再生过程进行了阐述。提出了优化催化剂使用的措施。     

蒽醌法钯催化剂工艺双氧水生产技术要点

从生产实践的角度分析了蒽醌法钯催化剂工艺双氧水生产过程中应注意的一些技术问题和安全事项,并提出了一些建议和措施。     

新型钯催化剂成功用于双氧水生产

<正>山东百川汇通化工科技有限公司研制生产的AHC-GII型钯催化剂,近期在山东海力化工股份有限公司15万t/a双氧水装置上成功应用,一次开车成功。AHC-GII型钯催化剂由先进的非均布负载技术制备而成。经中科院大连化学物理研究所分析检测、中石化股份     

新型钯催化剂成功用于双氧水生产

<正>山东百川汇通化工科技有限公司研制生产的AHC-GII型钯催化剂,日前在山东海力化工股份有限公司15万吨/年双氧水装置上成功应用,一次开车成功。     

双氧水生产中钯催化剂的使用若干问题的探讨

阐述了双氧水生产中钯催化剂使用中存在的几个重要问题,并提出改进措施.对双氧水生产中钯催化剂使用温度进行了探讨.通过建立氢化反应温度和氧化铝再生温度之间的关联和良性互动,即氧化铝再生温度随着氢化温度的升高而升高,从而提高氧化铝对降解物的再生效果,可以使钯催化剂运行温度较过去提高10 ℃以上.通过观察分析发现,停车前停氢不补氮气运行,导致固定床底压比顶压高出很多,底部封存的气体快速上升,冲击上层瓷球,是引起催化剂床瓷球下翻的重要原因,并提出改进措施.提出新催化剂和再生后的催化剂使用前不活化更好,再生的水流量对再生效果有较大影响,最好要达到工作液流量的20%～30%,才能有效清除污物.     

钯催化剂双氧水装置生产初期控制要点分析

以台湾南亚公司双氧水装置为例，介绍了钯催化剂固定床生产初期所遇到的一些常见问题及控制手段。即，在开车初期应通过使用氮气来控制氢化塔的压力，氢气的安全量可控制为工作液流量的5倍，氢化塔温度波动范围控制不超过1℃，加强对工作液组分的控制，保证系统的稳定性。     

蒽醌法双氧水生产中钯催化剂的使用与维护

介绍催化剂的结构组成与加氢催化原理,结合生产实践,指出影响钯催化剂活性的因素,比较了几种再生方法的优劣。     

Syngas production via CO2 reforming of methane using Co-Sr-Al catalyst

The effect of addition of strontium in Co based catalysts during CO₂ reforming of methane was investigated in the temperature range 500–700 °C. The Co/γ-Al₂O₃ supported catalysts with strontium as a promoter (0–2.25 wt%) were prepared by incipient wet impregnation method. Numerous techniques such as N₂ adsorption–desorption isotherm, H₂ temperature-programmed reduction (TPR), temperature-programmed desorption (TPD), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Transmission Electron Microscopy (TEM), pulse chemisorption and temperature-programmed oxidation (TPO) were applied for characterization of fresh and spent catalysts. The results of characterizations and catalyst activity test revealed that introduction of Sr in Co/γ-Al₂O₃ catalyst had significant effect on stability and coke suppression. The Sr addition improves the metal–support interaction as well as enhances the Lewis basicity of the catalyst. The improvement in basicity helps the chemisorption and dissociation of CO₂ over the catalyst which in turn reduces carbon deposition.     

吡啶改性Pd/SiO2催化剂用于H2和O2直接合成H2O2

引言过氧化氢(H2O2)是一种理想的绿色氧化剂,广泛应用于化学品合成、纺织、造纸、环保、食品、医药、冶金和农业等领域[1]。目前,蒽醌法[2-5]是工业上生产H2O2的主要方法。20世纪40年代,德国I.G.Farbenindustrie首先采用蒽醌法(又称Riedl-Pfleiderer法)工业化生产过氧化氢。该方法首先将2-烷基蒽醌(通常是2-乙基蒽醌)溶解于合适的有机溶剂中,溶液中的2-烷基蒽醌经催化剂催化加氢,被还原成蒽氢醌或5,6,7,8-四氢蒽氢醌,再经空气氧化得到蒽醌或四氢蒽醌和     

蒽醌加氢钯催化剂载体改性研究

针对Pd/Al2O3催化剂载体的改性进行研究,将1 000℃焙烧后的氧化铝粉末与未焙烧的活性氧化铝粉末按不同比例混合和焙烧制备载体,采用等体积浸渍法制得负载Pd的Pd/Al2O3催化剂。采用XRD、BET、NH3-TPD和HOT对载体以及催化剂进行表征,并考察催化剂的蒽醌加氢性能。结果表明,提高载体中焙烧后氧化铝粉末的比例,导致载体中γ-Al2O3减少和δ-Al2O3增多,载体酸性降低,Pd分散度变大,从而提高了催化剂氢化效率。当焙烧后氧化铝质量分数为40%时,分散度和活性表面积达到最大,晶粒度最小,氢化效率最高,催化活性最佳。     

Preparation of Pd/Al2O3/Al catalysts for CO removal

Aluminum was carefully anodized, then palladium salts were supported on its A1₂O₃ surface layer by ion-exchange. CO 3.76 vol% contained in the air can be eliminated at around 200 °C. Both anodization conditions and the nature of the precursor solutions affect catalyst nature, particularly the pH value of the precursor solutions. The pH value of the solution suitable for supporting active components is 5–6. Palladium, which is present as Pd²⁺ and Pd⁴⁺ after calcination,distributes uniformly on the support surface which had a honeycomb structure.     

异氟尔酮在蛋壳型Pd/Al2O3催化剂上的选择性加氢

采用等体积浸渍法制备出蛋壳型Pd/Al2O3催化剂,采用连续加氢固定床微反装置研究了异佛尔酮(IP)的选择性加氢反应,考察了载体焙烧温度、蛋壳层厚度、Pd负载量及粒子大小、溶剂等反应条件对Pd/Al2O3催化剂上IP选择性加氢的影响.结果表明,蛋壳型Pd/Al2O3是IP选择性加氢制备3,3,5-三甲基环己酮(TMCH)的优异催化剂,反应条件缓和,IP转化率及TMCH选择性均可达到99.5％以上,具有良好的工业应用前景.     

甲醇合成催化剂使用效果的影响因素及对策

介绍了甲醇合成催化剂的制造及使用过程,探讨了催化剂的失活方式及其机理,提出防止或消除这些因素、延长甲醇合成催化剂寿命的方法。     

The effect of ionic liquids on product yield and catalyst stability

The effect of ionic liquids on product yield and catalyst stability has been investigated through Suzuki cross-coupling of phenylboronic acid and 4-bromoacetophenone in organic solvents, ionic liquids and mixtures of organic solvents and ionic liquids.     

催化剂制备与研究 预处理对钯炭催化剂及其在肉桂醛加氢中性能的影响

采用不同预处理方式对活性炭表面进行改性,并制备钯炭催化剂。对活性炭的比表面积、孔结构等物理性质和含氧官能团种类以及钯炭催化剂进行表征,探究预处理对活性炭表面物化性能产生的变化和对钯炭催化剂在肉桂醛加氢反应中催化活性的影响。结果表明,氧化预处理使活性炭的比表面积和孔容下降,使钯炭催化剂上的钯粒子尺寸相对更小;碱预处理有一定的扩孔作用,使钯炭催化剂上的钯粒子尺寸更大。在肉桂醛加氢反应中,钯粒子尺寸越小的催化剂催化活性更高,而钯粒子尺寸更大的催化剂上肉桂醇选择性更高。     

A comparison of ethanol and water as the liquid phase in the direct formation of H2O2 from H2 and O2 over a palladium catalyst

Ethanol and water have been compared as the media in which hydrogen peroxide is produced from the reaction of H₂ and O₂ over a palladium catalyst. There are significant differences between the reaction in the two media with respect to the net rate of H₂O₂ formation, the state of the active Pd and the mechanism of the reaction. The reactions were carried out at atmospheric pressure and at 10 °C, with O₂ and H₂ being introduced in a 4/1 ratio through a glass frit. In ethanol, using 50 mg of 5 wt % Pd/SiO₂, 1.8 wt% H₂O₂ was attained in 7 h; whereas, about half this amount was attained in water. In addition, the net formation rate did not remain constant in water. Both systems were 0.17 N in HCl, which facilitated the formation of colloidal Pd in water but not in ethanol. The loss of activity in water is attributed to the instability of the colloid, which has been shown previously to be the active state of Pd. By contrast, these results show that supported Pd is the active state of the metal in the ethanol system. The mechanism for the formation of the nonselective product, water, also is affected by the media in which the reaction is carried out. In ethanol, water is formed by the direct reaction of H₂ and O₂, while in the aqueous phase, water appears to be formed both by the direct pathway and by the reduction of H₂O₂.     

Fabrication and characterization of La-added MgFe2O4 as catalyst support for CO oxidation

Fe-containing oxides can serve as excellent supports for precious metal catalysts. Therefore, we investigated the catalytic properties of noble metals supported on Fe-containing mixed oxides. MgFe₂O₄ and La-added MgFe₂O₄ (La-MgFe₂O₄) were prepared via complexation with malic acid and characterized by X-ray diffraction, N₂ adsorption–desorption, and Fe K-edge X-ray fine structure analysis. MgFe₂O₄ calcined at 400–800 °C has a spinel structure and is porous. The addition of La to MgFe₂O₄ increased the local structural disorder around Fe, suppressed grain growth, affected the pore size, and increased the specific surface area. In addition, a Pd-loaded La-MgFe₂O₄ catalyst was prepared and found to exhibit higher activity for CO oxidation than a representative Pd/γ-Al₂O₃ catalyst. Further, temperature-programmed reduction studies revealed that the reactivity of the surface lattice oxygen of La-MgFe₂O₄ was enhanced by the Pd loading. Further, diffuse reflectance Fourier transform infrared spectroscopy studies showed that the surface lattice oxygen reacted with CO to form CO₂.