Catalysed reactions batch reactor

Typically, reactors are made of stainless steel, which is resistant to most materials although the reactors have been known to catalyse reactions themselves [20], As mentioned above, scH20 corrodes steel, and mixtures of scC02 and water give an acid which is capable of corroding steel relatively quickly under supercritical conditions. Batch reactors generally consist of cylinders of steel with an... 

Phan, N T S. and Brown, D.H. and Styring, P. (2004). A faeile method for catalyst immobilisation on silica nickel catalysed Kumada reactions in mini-continuous flow and batch reactors. Green Chemistry, 6, 526-532. 

For catalysed liquid phase reactions that are first order overall, as found for ethanolamine (2, 11), the integrated equation for a batch reactor is... 

Reactions in which one reactant is gaseous, the other is in a liquid phase, and the catalyst is dispersed in the liquid phase, constitute a special but not unusual case, for example, the hydrogenation of a liquid alkene catalysed by platinum. A batch reactor is most commonly employed for laboratory scale studies of such reactions. Mass transport from the gaseous to the liquid phase may reduce the rate of such a catalytic reaction unless the contact between the gas and the liquid is excellent (see 1.6). 

The thermal behavior of a batch reactor strongly depends on the reaction energy. The adiabatic temperature rise depends on the reactants concentration. Therefore, the charge (i.e. the amount of reactants charged) must be strictly respected. Also the quality of the reactants must be strictly controlled, since impurities may catalyse secondary reactions leading to an increase of heat release with possibly dramatic consequences. 

The characteristics of the solid particles of catalyst (size, mechanical resistance, etc.) have to be adapted to the reactor. In many organic reactions catalysed by acid zeolites, the catalytic act is concentrated in the outer rim of the crystals and decreasing the zeolite particle size generates a significant gain in activity. However, the use of small particles in batch reactors causes serious drawbacks in the separation of the zeolite from the reaction mixture for the recovery of reaction products and the eventual reuse of the catalyst. Also, small particles cannot be used in fixed bed reactors because of excessive pressure drops. 

Nitroalkanols are intermediate compounds of /1-amino alcohols that are used extensively in many important syntheses. They are obtained by Henry s reaction through the condensation of nitroalkanes with aldehydes. Different nitro compounds have been reacted with carbonyl compounds in reactions catalysed by alkaline earth metal oxides and hydroxides/621 Among the catalysts examined, MgO, CaO, Ba(OH)2, and Sr(OH)2, exhibited high activity for the reaction of nitromethane with propionaldehyde. The yields were between 60 % (for MgO) and 26 % [for Sr(OH)2] at 313 K after 1 h in a batch reactor. The study of the influence of the pretreatment temperature of the solid showed that for MgO and CaO a... 

This reactor is used with solid or liquid catalysts and with liquid reactants, or for gas/liquid reactions in the presence of solid catalysts. Batch reactors are also frequently used, as closed systems with circulation of the gas, for reactions of gases catalysed by solids. Nowadays, relatively few detailed kinetic studies are performed using batch reactors. A common use of these reactors is for the rapid screening of catalysts particularily in high pressure/high temperature reactions. 

Anisole acetylation, which was one of the main reactions investigated, was first shown to be catalysed by zeolite ten years ago by Bayer (13), which was confirmed by Harvey et al. (14), then by Rhodia (15). Large pore zeolites and especially those with a tridimensional pore structure such as HBEA and HFAU were found to be the most active at 80°C, in a batch reactor with an anisole/acetic anhydride molar ratio of 5 and after 6 hours reaction, the yield in methoxyacetophenone (MAP) was close to 70% with HBEA and HFAU zeolites, to 30% with HMOR and 12% with HMFI. With all the zeolites and also with clays and heteropolyacids, the selectivity to the para-isomer was greater than 98%, which indicates that this high selectivity is not due to shape selective effects but rather to the reaction mechanism (electrophilic substitution). The lower conversion observed with HMOR can be related to the monodimensional pore system of this zeolite which is very sensitive to blockage by heavy secondary products. Furthermore, limitations in the desorption of methoxyacetophenone from the narrow pores of HMFI are probably responsible for the low activity of this intermediate pore size zeolite. 

Amide hydrolysis is a key step in the widespread strategy of protection/deprotection of amino groups for synthetic purposes, usually carried out in homogeneous phase with mineral acids. It is shown here that under mild conditions (batch reactor, liquid phase, 75°C) large pore zeolites (HY, HBeta, HMOR) can catalyse the hydrolysis of various aromatic amides. The best results are obtained over HY zeolite samples with Si/Al ratios of 16 and 30 e.g. complete and selective hydrolysis of 2-nitroacetanilide after 2-4 hours reaction for a zeolite/substrate ratio of 0.5 g/mmol. For similar values of the Si/Al ratio HBeta and rather all HMOR samples are much less active than HY samples, which is probably related to diffusion limitations. 

The oxidation of various hydrocarbons such as n-octane, cyclohexane, toluene, xylenes and trimethyl benzenes over two vanadium silicate molecular sieves, one a medium pore VS-2 and the other, a novei, iarge pore V-NCL-1, in presence of aqueous HjOj has been studied. These reactions were carried out in batch reactors at 358-373 K using acetonitrile as the solvent. The activation of the primary carbon atoms in addition to the preferred secondary ones in n-octane oxidation and oxidation of the methyl substituents in addition to aromatic hydroxyiation of alkyl aromatics distinguish vanadium silicates from titanium silicates. The vanadium silicates are also very active in the secondary oxidation of alcohols to the respective carbonyl compounds. V-NCL-1 is active in the oxidation of bulkier hydrocarbons wherein the medium pore VS-2 shows negligible activity. Thus, vanadium silicate molecular sieves offer the advantage of catalysing selective oxidation reactions in a shape selective manner. 

In conclusion, the use of zeolites as catalysts in the isomerization of isophorone oxide (1), yields up to 86% keto aldehyde. The formation of (4) by decarbonyla-tion of (2) could be reduced by increasing the catalyst loading in a liquid phase batch reactor or by conducting the reaction under short contact time in the gas phase. The heterogeneously-catalysed isomerization of teipene epoxides over zeolites is a suitable, non-polluting method of preparing relevant and useful aldehydes for the synthesis of perfumes and synthetic flavours. 

The heterogeneously-catalysed alkoxylation of a-pinene and limonene over P-zeolite provides excellent results in both a discontinuous batch reactor and a continuous flow-type apparatus with a fixed bed reactor. In both reactors, the use of methanol as addition compound and limonene as feedstock gives l-methyl-4-[a-methoxyisopropyl]-l-cyclohexene with the yield of 85% (conversion 93%, selectivity 92%). By means of variation of the reaction parameters, the limonene conversion can be adjusted within the range 40-90%. The selectivity to 1-methyl-4-[a-methoxyisopropyl]-l-cyclohexene remains always about 95%. 

Chapter 2 covers the basic principles of chemical kinetics and catalysis and gives a brief introduction on classification and types of chemical reactors. Differential and integral methods of analysis of rate equations for different types of reactions—irreversible and reversible reactions, autocatalytic reactions, elementary and non-elementary reactions, and series and parallel reactions are discussed in detail. Development of rate equations for solid catalysed reactions and enzyme catalysed biochemical reactions are presented. Methods for estimation of kinetic parameters from batch reactor data are explained with a number of illustrative examples and solved problems. 

The acid-epoxide reaction is straightforward and is catalysed by tertiary amines, phosphines or ammonium salts. Vinyl ester resins are diluted with a reactive monomer such as styrene, vinyl toluene or dicyclopentadiene acrylate. Similar to other unsaturated polyesters, the production of vinyl esters is carried out in batch reactors. The basic steps of the process are ... 

The reaction is the alcoholysis of acetic acid anhydride by methanol. Pyridine catalyses the conversion. For the start of the reaction, methanol is dosed as quickly as possible in a batch of acetic anhydride, which is mixed with some added acetic acid as acting accelerator for solving. By the injection of pyridine at an advanced state of conversion, the reaction velocity is once more abruptly enlarged. Then the conversion ends in a relatively short amount of time. The temperature fluctuations in the batch reactor are induced during the conversion by means of the installed electric heater. Figure 5.26 shows the courses of thermal reaction power q and the accompanying induced change in temperature within the batch reactor. 

The chloride is usually (but not always) stabilised in storage by addition of aqueous alkali or anhydrous amines as acid acceptors. A 270 kg batch which was not stabilised polymerised violently when charged into a reactor. Contact of the chloride (slightly hydrolysed and acidic) with rust led to formation of ferric chloride which catalysed an intermolecular Friedel-Craft reaction to form polybenzyls with evolution of further hydrogen chloride. Contact of unstabilised benzyl chloride with aluminium, iron or rust should be avoided to obviate the risk of polycondensation. See Benzyl bromide Molecular sieve... 

Ethyl formate is to be produced from ethanol and formic acid in a continuous flow tubular reactor operated at a constant temperature of 303 K (30°C). The reactants will be fed to the reactor in the proportions 1 mole HCOOH 5 moles C2H5OH at a combined flowrate of 0.0002 m3/s (0.72 m3/h). The reaction will be catalysed by a small amount of sulphuric acid. At the temperature, mole ratio, and catalyst concentration to be used, the rate equation determined from small-scale batch experiments has been found to be ... 

Phan, N.T.S., J. Khan, and P. Styring, Polymer-supported palladium catalysed Suzuki-Miyaura reactions in batch and a mini-continnous flow reactor system. Tetrahedron, 2005, 61 12065-12073. 

A chemical reaction of an aromatic amine with a chloronitro compound went out of control due to ferric chloride catalysed side reactions when the reaction mass became acidic. Natural soda ash used as an acid acceptor in the non-aqueous system was ineffective. The exothermic side reactions developed pressures above those normally encountered in the process. Synthetic soda ash had been used for all previous batches over a 20-year period. The difference in crystallinity made the natural soda ash less effective than the synthetic type normally used and it acted like an undercharge of soda ash. This permitted an acid build-up which formed ferric chloride as the reactor was made of stainless steel. 

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