Catalytic reactions in liquid phase

V. B. Sigitov, S. E. Kudaibergenov, E. A. Bekturov, Abstn 7th All-Union Conf. on Catalytic Reactions in Liquid Phase, Alma-Ata 1988, p. 101... 

Klabunovskii, E.L (1985) Enantioselective hydrogenation on heterogeneous and metallocomplex catalysts, in Catalytic Reactions in Liquid Phase, Proc. 6 All-Union Conf, 1983, Alma-Ata, Publ. Nauka, Acad. Kazakh. SSR., pp. 147-159. 

Klabunovskii, E.I. (1972) Some general questions of mechanism of stereospecific catalysis on diss5mimetric modified catalysts, "Catalytic Ractions in Liquid Phase", Proc. III. All-Union Conf on catalytical reactions in liquid phase, 1971, Nauka Kazakh. SSR, Alma-Ata, p. 70-75, Chem. Abstr. 1973, 79, 4824e. 

Catalytic Reactions in Liquid Phase", Proc. IV. All-Union Conf on catalytic reactions in liquid phase, Kazakh SSR, Alma-Ata, 1974,V.l, p. 

D. V. Sokol skii, A. A. Tsoi, and V. P. Shmonina, in Catalytic Reactions in Liquid Phase [in Russian], Izd. Akad. Nauk KazSSR, Alma-Ata (1967), p. 321. 

In industrial practice, three-phase catalytic reactors are often used, with gases like such as H2, H2O, NH3 or O2 as reactants. The process can be classified on the basis of these gases as hydrogenation, hydration, amination, oxidation, etc [3]. Among these processes, hydrogenation is by far the most important multiphase catalytic reaction. Recently, liquid- -phase methanol synthesis and the Fischer-Tropsch process were commercialized respectively... 

Co and Cr have been found to be incorporated into the lattice of aluminiumphosphates in a well dispersed manner [159]. Both elements assume two oxidation states in the lattice depending upon the pretreatment procedures. While it seems certain that during synthesis incorporation can be achieved and that these tetrahedrally coordinated atoms are stable in gas phase reactions, conclusive evidence is lacking that leaching is not an important side reaction in liquid phase studies. Indeed, it seems that for several reactions the highly active complexes that are leached out of the lattice and homogeneously dissolved in the reactant/solvent mixture dominate the catalytic properties. 

In addition to these mass transport steps, heat conduction can also be important in heterogeneously catalyzed processes. For exothermic reactions the heat generated at the catalytic site must be dissipated away from the catalyst and into the reaction medium while heat must be supplied to the active sites for endothermic reactions. In liquid phase processes heat transport is generally not a significant factor since the liquid tends to equalize the temperature throughout the reaction medium and, thus, facilitate temperature control. In vapor phase processes, however, heat transport can be a significant problem. 

The study of electron transfer (ET) at the polarized oil (0)/water (W) (or liquid/ liquid) interface is useful for understanding not only certain catalytic reactions in two-phase systems (e.g., liquid membranes, microemulsicms, micelles, etc.) but also energy conversion processes occurring at biomembranes. In 1979, Samec et al. [ 1,2] reported, as the first example, an ET between ferrocene (Fc) in nitrobenzene (NB) and Fe(CN)6 " in W ... 

Effective methods of chemical surface modification of mesoporous materials, to create robust surface structures with high catalytic activities in liquid phase reactions, are essential for the future development of environmentally friendly heterogeneous processes. In this paper we demonstrate the value of this methodology in different areas of organic chemistry and catalysis. 

In order to study reactions in liquid phase, it is necessary to develop new experimental techniques that will allow operando spectroscopy and transient studies of liquid phase heterogeneous catalytic reactions. Essential for such technique is a reactor module. Chromolith HPLC column (Merck) [1] with sihca foam in a polymer cartridge is suitable as a reactor for transient experiments because the high surface area silica foam can act as support with relatively low pressure drop. However, thermal stability of this HPLC column is limited to low temperatures because of the polymer housing (<150°C). It is... 

They evaluated B54 catalyst for the gas phase photo-WGS reaction. Increasing reaction temperature from 30 to 50 °C increases the H2 evolution from 115 to 540 pL/h. Also increasing hydrogen pre-treatment temperature from 500 to 700 °C increases the H2 evolution from 70 to 115 pL/h. The reactions in liquid phase also support this observation. Also, the catalytic activity improves in the presence of 100% illuminated light compared to the dark conditions. 

In order to study the properties of the carbon fibrils as a support material for an active component in a catalytic reaction, the liquid-phase hydrogenation of nitrobenzene was chosen as a test reaction and palladium as the active component. 

Hibbard, J. L. and D. Ramkrishna, Analysis of Phase Transfer Catalytic Reactions in Liquid-Liquid Systems, in Process and Fundamental Considerations of Selected Hydrometallurgical Systems, (M. C. Kuhn, Ed.) pp. 281-289. Society of Mining Engineers of American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc., New York, 281-289, 1981. 

Oxidation is one of the most important reactions in industrial organic synthesis [1-3] and can be carried out in both gas [4] and liquid [5,6] phases. Catalytic oxidation reactions in liquid phase were achieved in conditions of catalytic [5], photocatalytic [7], electrocatalytic [8], and photoelectrocatalytic [9] processes. At the same time, the new developments in the synthesis of materials led to the discovery of a large variety of catalysts and applications, including new catalysts for the liquid-phase oxidation reactions. A special interest in this sense was addressed to green and sustainable sources of oxidation [10]. 

Paul, M., Pal, N., Mondal, J., Sasidharan, M., and Bhaumik, A. (2012) New mesoporous magnesium aluminum mixed oxide and its catalytic activity in liquid phase Baeyer Villiger oxidation reaction. Chem. Eng. Set, 71,564 572. 

Reactions in liquid phase Catalytic reactions Ion (carbenium ions, carbon ions, inorganic ionic complexes) yOH OR RC+ +R OH 4 EC +H3O+ % OH 0... 

In comparison with catalytic reactions in compressed CO2 alone, many transition metal complexes are much more soluble in ionic liquids without the need for special ligands. Moreover, the ionic liquid catalyst phase provides the potential to activate and tune the organometallic catalyst. Furthermore, product separation from the catalyst is now possible without exposure of the catalyst to changes of temperature, pressure, or substrate concentration. 

Chapter 11 treats reactors where mass and component balances are needed for at least two phases and where there is interphase mass transfer. Most examples have two fluid phases, typically gas-liquid. Reaction is usually confined to one phase, although the general formulation allows reaction in any phase. A third phase, when present, is usually solid and usually catalytic. The solid phase may be either mobile or stationary. Some example systems are shown in Table 11.1. 

The aim of the present work was the investigation of the catalytic reactivity of different salts (K, NH4, Cs ) of H3PW12O40 and H4SiWi2O40 with various compositions in continuous liquid phase alkylation and its comparison with n-butane isomerisation reaction in gas phase. 

Gomez-Sainero et al. (11) reported X-ray photoelectron spectroscopy results on their Pd/C catalysts prepared by an incipient wetness method. XPS showed that Pd° (metallic) and Pdn+ (electron-deficient) species are present on the catalyst surface and the properties depend on the reduction temperature and nature of the palladium precursor. With this understanding of the dual sites nature of Pd, it is believed that organic species S and A are chemisorbed on to Pdn+ (SI) and H2 is chemisorbed dissociatively on to Pd°(S2) in a noncompetitive manner. In the catalytic cycle, quasi-equilibrium ( ) was assumed for adsorption of reactants, SM and hydrogen in liquid phase and the product A (12). Applying Horiuti s concept of rate determining step (13,14), the surface reaction between the adsorbed SM on site SI and adsorbed hydrogen on S2 is the key step in the rate equation. 

Most reactions run by organic chemists are in the liquid phase. Consequently, organic chemists of the heterogeneous catalytic variety have developed special techniques and apparatuses for running catalytic reactions in the liquid phase. 

CoSalen Y carries oxygen as a cargo.72 The catalytic properties of the zeolite-encapsulated metal complexes depend mainly on the complexed metal atoms, which are used usually as oxidation catalysts but other applications are also beginning to emerge. The zeolite-encapsulated catalysts can be regarded as biomimetic oxidation catalysts.73 In liquid-phase oxidation reactions catalyzed... 

Acidic micro- and mesoporous materials, and in particular USY type zeolites, are widely used in petroleum refinery and petrochemical industry. Dealumination treatment of Y type zeolites referred to as ultrastabilisation is carried out to tune acidity, porosity and stability of these materials [1]. Dealumination by high temperature treatment in presence of steam creates a secondary mesoporous network inside individual zeolite crystals. In view of catalytic applications, it is essential to characterize those mesopores and to distinguish mesopores connected to the external surface of the zeolite crystal from mesopores present as cavities accessible via micropores only [2]. Externally accessible mesopores increase catalytic effectiveness by lifting diffusion limitation and facilitating desorption of reaction products [3], The aim of this paper is to characterize those mesopores by means of catalytic test reaction and liquid phase breakthrough experiments. 

A detailed study of microwave activation of catalytic reactions in the liquid phase has recently been performed by Hajek et al. [58-60], Scheme 10.13. 

The reactor is equipped with magnetic stirrer, microwave power and temperature control by computer and can operate under pressure. Even though it was developed for homogeneous organic synthetic reactions, it can be used also for heterogeneous catalytic reactions in the liquid phase. 

The HTE characteristics that apply for gas-phase reactions (i.e., measurement under nondiffusion-limited conditions, equal distribution of gas flows and temperature, avoidance of crosscontamination, etc.) also apply for catalytic reactions in the liquid-phase. In addition, in liquid phase reactions mass-transport phenomena of the reactants are a vital point, especially if one of the reactants is a gas. It is worth spending some time to reflect on the topic of mass transfer related to liquid-gas-phase reactions. As we discussed before, for gas-phase catalysis, a crucial point is the measurement of catalysts under conditions where mass transport is not limiting the reaction and yields true microkinetic data. As an additional factor for mass transport in liquid-gas-phase reactions, the rate of reaction gas saturation of the liquid can also determine the kinetics of the reaction [81], In order to avoid mass-transport limitations with regard to gas/liquid mass transport, the transfer rate of the gas into the liquid (saturation of the liquid with gas) must be higher than the consumption of the reactant gas by the reaction. Otherwise, it is not possible to obtain true kinetic data of the catalytic reaction, which allow a comparison of the different catalyst candidates on a microkinetic basis, as only the gas uptake of the liquid will govern the result of the experiment (see Figure 11.32a). In three-phase reactions (gas-liquid-solid), the transport of the reactants to the surface of the solid (and the transport from the resulting products from this surface) will also... 

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