Fixed bed/continuous

Reaction ran in continuous fixed-bed configuration 63°C, 2.8 LHSV, 80 20 OibMeOH ... 

The liquid phase alkoxylation of limonene (3) with C4-C4 alcohols to 1-methyl-4-[a-alkoxy-isopropyl]-l-cyclohexene (5) was carried out both in batch and continuous fixed-bed reactor at 60 °C on various acidic catalysts (Scheme 3.1) [16]. The best yields were obtained in batch (85%) or continuous reactor (81%) using a /1-type zeolite with Si02/Al203 = 25. 

In the following, a model of an anaerobic digestion process carried out in a continuous fixed bed reactor for the treatment of industrial wine distillery vinasses is considered [10] ... 

Abstract The principle of catalytic SILP materials involves surface modification of a porous solid material by an ionic liquid coating. Ionic liquids are salts with melting points below 100 °C, generally characterized by extremely low volatilities. In the examples described in this paper, the ionic liquid coating contains a homogeneously dissolved Rh-complex and constitutes a uniform, thin film, which itself displays the catalytic reactivity in the system. Continuous fixed-bed reactor technology has been applied successfully to demonstrate the feasibility of catalytic SILP materials for propene hydroformylation and methanol carbonylation. 

The use of catalytic SILP materials has been reviewed recently [10] covering Friedel-Crafts reactions [33-37], hydroformylations (Rh-catalyzed) [38], hydrogenation (Rh-catalyzed) [39,40], Heck reactions (Pd-catalyzed) [41], and hydroaminations (Rh-, Pd-, and Zn-catalyzed) [42]. Since then, the SILP concept has been extended to additional catalytic reactions and alternative support materials. In this paper we will present results from continuous, fixed-bed carbonylation and hydroformylation reactions using rhodium-based SILP catalysts as reaction examples demonstrating the advantages of the SILP technology for bulk chemical production. 

To verify the homogeneous nature of Rh-3-SILP catalysts, as previously suggested based on IR and NMR spectroscopic studies, [30] kinetic experiments have also been conducted with the catalyst. Here, a continuous fixed-bed reactor setup equipped with online gas-chromatography, described elsewhere in detail, [31] was applied. The general rate law for the hydroformylation of propene was assumed ... 

The disproportionation and isomerization of trimethylbenzene(TrMB) were studied at 200°C using a continuous fixed bed reactor. The reactant TrMB was diluted with nitrogen in a molar ratio of 1 9. The cracking of cumene was carried out at 400 C using a pulse reactor. The catalyst was treated in a stream of nitrogen for 1 h at a desired temperature in the range 400-600°C prior... 

The selective oxidation of a 50% aqueous solution of glycerol was performed at 50 °C with an oxygen/glycerol ratio of 2, in a continuous fixed bed process using a Pt-Bi catalyst supported on charcoal. Here, a DHA selectivity of 80% at a conversion of 80% was obtained. 

Enzymes, when immobilized in spherical particles or in films made from various polymers and porous materials, are referred to as immobUized enzymes. Enzymes can be immobilized by covalent bonding, electrostatic interaction, crosslinking of the enzymes, and entrapment in a polymer network, among other techniques. In the case of batch reactors, the particles or films of immobilized enzymes can be reused after having been separated from the solution after reaction by physical means, such as sedimentation, centrifugation, and filtration. Immobilized enzymes can also be used in continuous fixed-bed reactors, fluidized reactors, and membrane reactors. 

H2 conversion was also typically lower than total, ranging from 30 to 70%. A H2 recycle is thus necessary. Staged (sequential) addition of H2 to maintain a more uniform 02 H2 ratio in the reactor and avoid excess 02 has also been shown to improve performances. Batch-type autoclave or continuous fixed bed (trickle-bed) or stirred reactors have been used. Operations were typically under pressure in the 50-100 bar range, again with the exception of the cited CSIR patents. The reaction temperature ranged from 4 to 605 °C. Upon decreasing the temperature, H2 solubility increases, but the catalyst specific activity decreases. The productivity should thus pass through a maximum nevertheless this depends from case to case. Table 8.3 summarizes selected results from recent patents. 

The partial oxidation of alcohols, to afford carbonyl or carboxylic compounds, is another synthetic route of high industrial interest For this, scC02 was investigated as a reaction medium for the aerobic oxidation of aliphatic, unsaturated, aromatic and benzylic acids with different catalytic systems, mainly based on the use of noble metals, both in batch [58-64] and in continuous fixed-bed reactors [65-70]. In this context, very promising results have been obtained when studying the catalytic activity of supported palladium and gold nanoparticles in the oxidation of benzyl alcohol to benzaldehyde these allowed conversions and selectivities in excess of 90% to be achieved [71-73]. 

Pd/ Deloxan APII (fixed-bed) Continuous fixed-bed process 150-200 2.5 2009.2... 

The combination of Deloxan-supported precious-metal fixed-bed catalysts and the use of liquid, near-critical, or supercritical C02 and/or propane mixtures creates new possibilities for continuous fixed-bed hydrogenations with significantly improved space-time yields and catalyst lifetimes. Short residence times and well-balanced diffusion and desorption of products and reactants results in a decrease in undesirable by-products and therefore higher selectivity. The characteristics of high-pressure hydrogenations in near-critical or supercritical fluids can be summarized as follows ... 

High-throughput testing was accomplished using a system of 16 continuous fixed-bed parallel microreactors, able to work up to 80 bar. The principal characteristics of this reactor are summarized as ... 

There is a strong incentive for the development of a continuous fixed bed catalytic process for regioselective nitration of aromatics. Solid acid catalysts are able to carry out the reaction, but, for most of them, selectivities are similar to those obtained using nitric acid plus sulfuric in homogeneous phase. 

Equipment and Procedure. The fixed bed reactor pilot plant is shown schematically in Figure 1. The reactor was operated as a continuous fixed bed reactor, with recycle of the hydrogen. 

Hydroprocessing studies were carried out in continuous fixed-bed tubular reactors containing 50-200 cm3 of catalyst. All reactors were operated in downflow mode. To facilitate mass balance data acquisition,... 

Furthermore, in respect to the regioselectivity of the ring opening reaction of oxiranes, electronic as well as steric factors can play a role. These general considerations stimulate the use of zeolites and non zeolitic molecular sieves as heterogeneous catalysts for such rearrangement reactions in the liquid or in the gas phase in a slurry reactor and in a continuous fixed bed reactor, respectively. 

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