Regeneration studies on nickel molybdate catalysts used for the upgrading of coal-derived liquids

Nickel molybdate catalysts used in several different upgrading reactions of coal-derived materials from low-rank Australian coals have been regenerated and their activity assessed using a number of physical and chemical techniques. Regeneration of spent coked catalysts for 20 hours in air at 450°C was sufficient to restore chemical hydrogenation activity to catalyst used for pre-asphaltene, asphaltene and oil upgrading, provided poisoning of the catalyst surface by other impurities, principally chlorine-containing molecules, had not occurred.     

Reclamation of nickel from spent nickel catalyst

Spent nickel catalyst containing an average 9.6% nickel was obtained locally from an oil hydrogenation industry. It was digested with 1–3N HCl, HNO₃, H₂SO₄ and mixtures thereof in one to three stages of durations ranging from one to three hr at 100°C using spent nickel catalyst to acid proportions of 1:3 to 1:8 (w/v). Nickel recoveries of over 94% were obtained when one part of spent catalyst was digested for three hr with six or more parts of 3N mixture of HCl and HNO₃ (3:1, v/v). Acid extracts of spent nickel catalyst obtained using HCl, H₂SO₄ and mixtures thereof were treated with NaOCl to convert their content of iron in the ferric form. The iron from the nickel extract was precipitated out in the form of ferric hydroxide at pH 6.0. Nickel from the iron-freed acid extracts was recovered at pH 8.5±0.5 as nickel hydroxide. Nickel formate was prepared by refluxing nickel hydroxide with 10% formic acid in about 6% excess to stoichiometric requirements for 30 min. The dried nickel formate was reduced in peanut oil at 230°C to 270°C for 0.25 to 2.75 hr. The reduction at 260°C on kieselguhr support, employing nickel formate:oil:support in ratio of 50:43:7, for two hr provided catalyst of maximum activity. The hydrogenation activity of the reclaimed catalyst, assessed by standard AOCS procedure, was greater than that of the parent catalyst. Presented at the AOCS Meeting in New Orleans, LA, in May 1987.     

Regeneration of silica-alumina catalyst particles

The oxidation of carbon on a silica-alumina catalyst has been investigated in the temperature range 420–544°c under differential reactor conditions. The reaction was first order in oxygen but the order with respect to the deposited carbon could be interpreted as either a first-order or surface reaction process. However, a statistical analysis and mechanistic considerations suggest that the surface reaction mechanism is more probable.     

Kinetics of nickel catalyst poisoning

Hydrogenation was done in a “dead-end” type of reactor with automatic recording of hydrogen absorption. In order to determine the poisoning rates of various nickel catalysts with phospholipids, allyl isothiocyanate (AITC), free fatty acids, sodium soaps and products of lipid oxidation, these poisons were added to the reaction system while the reaction was approaching the highest rate. The kinetic curves show that, at the moment of inhibitor addition, the reaction rate decreases immediately; for AITC, the reaction is even stopped for a certain period of time. This observation proves inhibitors are adsorbed at the metal surface immediately after introduction to the system. In some cases, after decreasing the reaction rate, we have observed subsequent acceleration of the reaction that may result from depoisoning processes at the catalyst surface.     

化学镀镍老化液再生技术研究现状

介绍了国内外化学镀镍老化液再生技术研究现状。     

Supported nickel catalyst from hydroxycarbonate of nickel and aluminium

The hydroxycarbonate of nickel and aluminium (Ni/ Al = 3) with a hydrotalcite-like structure is an outstanding precursor of the active component of supported nickel catalysts. Good mechanical strength and suitable nickel content of these catalysts, which are necessary for practical applications, can be achieved by mechanical mixing of this compound with an additional support. The catalyst prepared from a mixture of 56.5 wt-% of nickel-aluminium hydroxycarbonate and 43.5 wt-% of γ-alumina was proven to have a stable catalytic activity in the methanation reaction at 2 MPa and 800 K.     

The activity of nickel chromite catalyst

The nickel oxide—chromia gel powder solid-state reaction was followed at 400° – 1200 °C. The reaction fits kinetically the Jander and/or Ginstling-Brounshtein equation. Catalytic activity towards H₂O₂ decomposition was correlated with pertaining formation structural changes including tetragonal deformation of NiCr₂O₄.     

Separation of nickel catalyst by microfiltration

Ceramic membranes with pore size of 0.1 and 0.2 µm are used for the separation of nickel catalyst. Effect of trans‐membrane pressure (TMP), linear velocity, temperature and nickel content (solute) on flux and rejection has been investigated. The flux increased with increase in pore size of the membrane. The rejection characteristics were similar for 0.1 and 0.2 µm membranes. The nickel content and iodine value of the membrane‐filtered oil was comparable with that of conventional processes. Permeate flux increased with increase in temperature. Flux increased with increase in linear velocity and a marginal rise was observed above 2.09 m/s. The rejection characteristics were only slightly affected by higher linear velocity. The flux improved after back flushing. The average flux was higher with back flushing as compared to continuous (with out back flushing) filtration process. The results indicated that the secondary layer effect was more pronounced in microfiltration. The flux decreased with increase in solute concentration. The rejection characteristics were not affected by solute concentration. The rejection characteristic of the membranes remained unaltered after membranes were repeatedly cleaned with sodium hydroxide and HCl solutions, however, the flux was decreased marginally.     

新型松香歧化反应催化剂的再生研究

采用溶胶-凝胶-沉淀法制备了mN/lL-T催化剂,用于松香歧化反应。失活催化剂先用乙醇洗涤,经过烘烤干燥后,在通入空气+氮气的管炉中焙烧1~3 h,温度控制在450 ℃。失活催化剂经过再生处理后,催化性能有较大改善。     

Hydrogenation of cyclopentadiene on a nickel catalyst

The hydrogenation of cyclopentadiene on Ni catalyst was carried out with a fixed bed reactor. The initial reaction rates were expressed by the following equations. The activation energies of overall-and surface-reaction rates were, respectively, 1.9 and 6.5 kcal/mol and the heats of adsorption of hydrogen and cyclopentadiene were, respectively, 5.6 and 1.6 kcal/mol. The hydrogenation of cyclopentadiene on Ni catalyst is a consecutive reaction passing through cyclopentene, where the activation energy of the 1st stage is higher than that of the 2nd one, namely, E₁ > E₂. At the lower ratio of P_H/P_C, cyclopentene is produced with 100% selectivity, whereas, increasing P_H/P_C or W/F₀, the selectivity decreases. At the intermediate reaction temperature, there appears the minimum selectivity. This phenomenon is considered to be due to E₁ > E₂.     

Regeneration of a catalyst based on a SAPO‐34 used in the transformation of methanol into olefins

The regeneration by coke combustion of a catalyst based on a SAPO‐34 used in the transformation of methanol into olefins (ethene and propene) has been studied. It has been observed that coke combustion kinetics are strongly dependent on the nature of the coke (H/C ratio), which in turn is a consequence of the reaction conditions (especially of the water content in the feed) and of the ageing level of the coke prior to its combustion. A severe ageing treatment is needed in order for combustion kinetics to be reproducible. Combustion is delayed due to the fact that coke is not an inert material but is bound to the acid sites. © 1999 Society of Chemical Industry     

Cyclohexane dehydrogenation on a nickel catalyst: Kinetics and catalyst fouling

The main reaction and deactivation kinetics of cyclohexane dehydrogenation in the presence of hydrogen has been investigated at atmospheric pressure over a nickel kieselguhr catalyst in the temperature range 583–623 K. The rate of reaction for the fresh catalyst increased with increasing temperature, cyclohexane and hydrogen partial pressures whereas it decreased with an increase in the benzene partial pressure. The experimental data could be adequately modelled by a power law rate expression. The catalyst activity decreased with run time due to catalyst fouling by coke deposition. The rate of deactivation was independent of cyclohexane partial pressure, increased with increasing benzene concentration and decreased with increasing hydrogen partial pressure. It is postulated that coke is most likely formed by the successive dehydrogenation of benzene.     

二甲醚羰基化催化剂的烧炭再生

以水热合成的H-MOR分子筛催化剂,通过对二甲醚羰基化反应失活后催化剂进行再生,考察了不同再生气体、再生温度、O₂体积分数、烧炭升温速率等条件,烧炭后催化剂上二甲醚羰基化活性性能。TPO表征结果表明：反应后H-MOR分子筛上有两种不同性质的积炭。积炭催化剂在3%（体积） O₂/N₂气氛中,从室温以2℃·min^-1升温至320℃恒温一段时间,然后以相同速率升温至550℃进行烧炭,再生催化剂活性几乎完全恢复。NH₃-TPD和BET表征结果表明,再生催化剂活性得以恢复是因为优化了烧炭方案,分子筛表面积炭能够被烧除干净同时分子筛孔道不被破坏。     

苯乙烯-异戊二烯-苯乙烯(SIS)嵌段共聚物的镍系催化加氢

Ni(naph) 2 /Al(i-Bu) 3 常温、常压催化SIS加氢的研究结果表明 ,反应只发生在PIp中的不饱和双键上 ,苯环不参与加氢反应 ;实验条件下 ,PIp中的 3,4-链节、1,4-链节具有相同的加氢活性 ;在 5 0℃、0 .1MPa氢压、1.90× 10 -4 mol/g·SIS的Ni用量、Al与Ni的摩尔比为 5时 ,SIS的加氢度可达92 .6 %;陈化后的催化剂显示出较高的加氢活性。     

镍系催化丁二烯聚合催化剂制备工艺的改进

采用超声波对催化剂进行处理改善了催化剂的分散性，配合添加微量水调节聚合反应的诱导期和体系的稳定性，拓宽了Al/B对相对分子质量的调节范围，单体转化率大于80％的条件下，制得了门尼黏度大于80的高相对分子质量基础顺丁橡胶。     

负载型磷化镍催化剂的制备及其催化应用

综述了近年来负载型磷化镍催化剂在制备方法(还原法、热解法和溶剂热法)、活性组分和载体改性及其催化应用方面的研究进展,并对比了各种制备方法的优缺点,其中还原法流程简单,但所用温度较高,时间较长;热解法所需温度较低,制备过程简单,但易于生成副产物水;而溶剂热法具有所需温度低,物相形成过程易控制等优点。负载型磷化镍催化剂由于其良好的加氢氢解及烷烃临氢异构化等反应性能,是一类更加廉价的新型催化剂,具有很好的发展前景。     

Geometric isomerization of fatty acids with nickel catalyst

Cis-trans isomerization studies were performed on commercial oleic acid and refined sunflower oil. Reactions were carried out at constant temperature, under inert atmosphere (without hydrogen), using an industrial nickelcontaining hydrogenation catalyst. With sunflower oil, hydrogen transfer and polymerization were concurrent with the formation ofrans isomers. Based on work done in partial fulfillment of requirements for completion of the doctoral dissertation of Maria A. Grompone.     

Vinyl polymerization of norbornene over supported nickel catalyst

A series of nickel complexes, bis(salicylideneiminato)nickel(II), were supported on spherical MgCl₂ and SiO₂. Scanning electron microscopy, energy‐dispersed X‐ray spectroscopy, and the BET method for surface areas measurements were utilized to examine the supporting process of the catalysts. The particle morphology of the original support is retained and replicated throughout the supported catalyst preparation and norbornene polymerization. Spherical polymer particle morphology was achieved, without reactor fouling. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2233–2240, 2006     

从失活的油脂加氢催化剂中回收镍

采用酸浸后再氨络合的方法从废油脂加氢催化剂中回收镍，镍的回收率最高可达99%以上。酸浸前先在适当温度下焙烧废催化剂样品有利于镍的溶出。使用由盐酸与硫酸以适当比例构成的混酸比使用单一盐酸或硫酸更有利于镍的溶出。加氨时，采用反加方式比正加和并流方式所得镍的回收率高。     

采用陶瓷膜回收纳米镍催化剂

引言 纳米镍催化剂在有机物如苯、硝基苯、对硝基苯酚等的催化加氢和2-丁醇的催化脱氢等方面有着广泛的应用[1-4].有文献报道[5-7],悬浮态非负载型催化剂的催化活性高于负载型催化剂.使用悬浮态的纳米催化剂可大大提高反应速率,降低催化剂的使用量,这对提高催化剂的使用效率,降低生产成本,增加生产效益是很有价值的.