Hydrolysis reactor conditions

Autohydrolysis enables the selective hydrolysis of hemicelluloses to a mixture mainly consisting of oligosaccharides and monosaccharides. The monosaccharide content can be increased under harsher reactor conditions, but then monosaccharides can undergo decomposition reactions, thereby increasing the content of potential fermentation inhibitors in hydrolysates. 

All commercial production of PG is by noncatalytic hydrolysis of PO carried out under high pressure and high temperature. A large excess of water is used in the conversion of PO into a mixture of mono-, di-, and tripropylene glycols. Typical product distribution is 90% PG and 10% coproducts. Hydration reactor conditions are 120-190°C at pressures up to 2170 kPA. After the hydration reaction is completed, excess water is removed in multieffect evaporators and drying towers, and the glycols are purified by high vacuum distillation. 

Detection methods. - Various metallic wires were investigated for use in constant-potential amperometric detection of carbohydrates in HPAEC eluates. Copper proved best, and when conditions were optimized, picomole amounts of various sugars could be detected. Conditions fcH-post-column generation of fluorescence by reaction of mono- to tri-saccharides with an ethanolamine-boric acid reagent were optimized, and applied to the h.p.Lc. analysis (anion-exchanger, alkaline aq. borate eluant) of mono- and di-saccharides in wine. The detection of disaccharides was markedly improved if a post-column acid-catalysed hydrolysis reactor was added prior to detection. ... 

Figure 1.16 The hydrolysis of p-nitrophenyl acetate under different reactor conditions showing the clear advantage of reaction time to that observed in a round-bottomed flask.

For other elements of variable valence, su( h as technetium, the amount of the element in solution is determined by the stable valence state under reactor conditions. In general, the higher valence states lietter resist hydrolysis and remain in solution. Thus at 275°C in 0.02 m UO2SO4 Tc(VII) is reduced to Tc(IV) if hydrogen is present, and only 12 mg/kg H2O remains in solution. However, a slurry of TCO2 in the same solution but with oxygen present dissolves to give a solution at 275 C with a technetium concentration of more than 9 g/kg H2O. The same qualitative behavior is observed with ruthenium. Selenium and tellurium in the hexapositive state are much more soluble than when in the tetrapositive state [4]. 

There are four processes for industrial production of ahyl alcohol. One is alkaline hydrolysis of ahyl chloride (1). In this process, the amount of ahyl chloride, 20 wt % aqueous NaOH solution, water, and steam are controhed as they are added to the reactor and the hydrolysis is carried out at 150 °C, 1.4 MPa (203 psi) and pH 10—12. Under these conditions, conversion of ahyl chloride is 97—98%, and ahyl alcohol is selectively produced in 92—93% yield. The main by-products are diahyl ether and a small amount of high boiling point substance. The alkaU concentration and pH value are important factors. At high alkah concentrations, the amount of by-product, diahyl ether, increases and at low concentrations, conversion of ahyl chloride does not increase. 

In the first step of the reaction, the acetoxylation of propylene is carried out in the gas phase, using soHd catalyst containing pahadium as the main catalyst at 160—180°C and 0.49—0.98 MPa (70—140 psi). Components from the reactor are separated into Hquid components and gas components. The Hquid components containing the product, ahyl acetate, are sent to the hydrolysis process. The gas components contain unreacted gases and CO2. After removal of CO2, the unreacted gases, are recycled to the reactor. In the second step, the hydrolysis, which is an equhibrium reaction of ahyl acetate, an acid catalyst is used. To simplify the process, a sohd acid catalyst such as ion-exchange resin is used, and the reaction is carried out at the fixed-bed Hquid phase. The reaction takes place under the mild condition of 60—80°C and ahyl alcohol is selectively produced in almost 100% yield. Acetic acid recovered from the... 

Cyanopyridines are usually manufactured from the corresponding picoline by catalytic, vapor-phase ammoxidation (eq. 7) in a fixed- or fluid-bed reactor (28). 3-Cyanopyridine (25) is the most important nitrile, as it undergoes partial or complete hydrolysis under basic conditions to give niacinamide... 

The ratio of cycHc to linear oligomers, as well as the chain length of the linear sdoxanes, is controlled by the conditions of hydrolysis, such as the ratio of chlorosilane to water, temperature, contact time, and solvents (60,61). Commercially, hydrolysis of dim ethyl dichi oro sil a n e is performed by either batch or a continuous process (62). In the typical industrial operation, the dimethyl dichi orosilane is mixed with 22% a2eotropic aqueous hydrochloric acid in a continuous reactor. The mixture of hydrolysate and 32% concentrated acid is separated in a decanter. After separation, the anhydrous hydrogen chloride is converted to methyl chloride, which is then reused in the direct process. The hydrolysate is washed for removal of residual acid, neutralized, dried, and filtered (63). The typical yield of cycHc oligomers is between 35 and 50%. The mixture of cycHc oligomers consists mainly of tetramer and pentamer. Only a small amount of cycHc trimer is formed. 

Commercial production of these acids essentially follows the mechanistic steps given. This is most clearly seen in the Exxon process of Figure 1 (32). In the reactor, catalyst, olefin, and CO react to give the complex. After degassing, hydrolysis of this complex takes place. The acid and catalyst are then separated, and the trialkylacetic acid is purified in the distillation section. The process postulated to be used by Shell (Fig. 2) is similar, with additional steps prior to distillation being used. In 1980, the conditions used were described as ca 40—70°C and 7—10 MPa (70—100 bar) carbon monoxide pressure with H PO —BF —H2O in the ratio 1 1 1 (Shell) or with BF (Enjay) as catalyst (33). 

The advance of sulfur trioxide as sulfating agent largely depended on advances in sulfonation/sulfation reactor development and changes in raw material quality. Undiluted sulfur trioxide cannot be used as a sulfating agent except in special cases where suitable equipment is used because of its violent nature. Sulfur trioxide diluted in an inert gas, usually air, when used in batch processes can cause excessive dehydration and dark-colored products. However, batch processes were used years ago and inert liquid solvents were often suggested or used to moderate the reaction. Inadequate reaction conditions lead to a finished product that can contain dialkyl sulfate, dialkyl ether, isomeric alcohols, and olefins whereas inadequate neutralization conditions can increase the content of the parent alcohol due to hydrolysis of the unstable acid sulfate accompanied by an increase of mineral sulfate. 

The glycolysis of PETP was studied in a batch reactor at 265C. The reaction extent in the initial period was determined as a function of reaction time using a thermogravimetric technique. The rate data were shown to fit a second order kinetic model at small reaction times. An initial glycolysis rate was calculated from the model and was found to be over four times greater than the initial rate of hydrolysis under the same reaction conditions. 4 refs. 

The main purpose of this work is development of small-scale and mobile dsMmposition system of these chemicals. A number of studies on decomposition of organophosphorus insecticides have been conducted [1-3]. It is well known that or nophosphorus insecticides are decomposed by hydrolysis under alkaline condition, and its meciianisms have been studied [4], Even so, relatively few papers have address the devdopment of kinetic equations for reactor desipi. In this study, we aim to get kinetic equaticms for their decomposition under alkaline condition. As organophosphtous, we used parathion, fenitrothion, diazinon, malathion and phenthoate. 

A system of parallel reactions as shown in Fig. 5.3-9 was studied by Paul et at. (1992). The reactions are an acid-base neutralization and a base-catalysed hydrolysis of product (C). The labile compound (Q is in solution in an organic solvent, and aqueous NaOH is added to raise the pH from 2 to 7. Enolization occurs under basic conditions and is accompanied by irreversible decomposition (ring opening), which is not shown in the figure. The system was studied in the laboratory using the 6-Iitre reactor shown in Fig. 5.3-10. 

Different effects of formaldehyde on the hydrolysis of urea are reported. On the one hand, Garrido and colleagues,3 applying anoxic conditions, observed that an inhibitory effect started at 50 mg/L formaldehyde and the levels of inhibition were 50% and 90% for concentrations of formaldehyde of 100 mg/L and 300 mg/L, respectively. Similar effects were found by Campos and colleagues,33 working with an anoxic USB, who observed that formaldehyde concentrations in the reactor of 250 to 300 mg/L caused an inhibition of around 53%. This inhibition on the ureolytic activity was also reported by Walker.36 On the other hand, Eiroa and colleagues37 carried out batch assays at different initial urea concentrations from 90 to 370mg/L N-urea in the presence of 430 mg/L formaldehyde. They observed that a complete hydrolysis was achieved and initial urea hydrolysis rates remained constant. 

Chakrabarti, T. and Subrahmanyam, P.V.R., Biological hydrolysis of urea in a continuous flow stirred tank reactor under laboratory conditions—a bench scale study, Proc. 36th Industrial Waste Conference, Purdue University, pp. 477, 1981. 

The C-5 sugar alcohols produced from the hydrolysis of hemicellulose are both xylitol and arabitol [6], Equivalence testing was performed with Ni/Re catalyst in the batch reactor to verily similar performance between xylitol and arabitol feedstocks. The operating conditions were 200°C and 8300kPa H2 using the procedure outlined in section Catalyst Screening section. 

Hydrolysis of sucrose in the presence of Amberlite 200C [47-49]. Reaction conditions 9% aqueous solution of sucrose, a stirred tank [47] or continuous-flow fixed-bed reactor [48, 49]. 

Monoglyceride (MG) is one of the most important emulsifiers in food and pharmaceutical industries [280], MG is industrially produced by trans-esterification of fats and oils at high temperature with alkaline catalyst. The synthesis of MG by hydrolysis or glycerolysis of triglyceride (TG) with immobilized lipase attracted attention recently, because it has mild reaction conditions and avoids formation of side products. Silica and celite are often used as immobilization carriers [281], But the immobilized lipase particles are difficult to reuse due to adsorption of glycerol on this carriers [282], PVA/chitosan composite membrane reactor can be used for enzymatic processing of fats and oils. The immobilized activity of lipase was 2.64 IU/cm2 with a recovery of 24%. The membrane reactor was used in a two-phase system reaction to synthesize monoglyceride (MG) by hydrolysis of palm oil, which was reused for at least nine batches with yield of 32-50%. 

DR. PATEL One reason for much of the interest which prevails in this area right now, especially with iron ll), has to do with the corrosion of steel in industry and also in nuclear reactors. Normally one thinks of forming precipitates or particles by adding base to a solution and cooling it down. If iron(III) solutions are made more acidic and if you raise the temperature, these conditions lead to the formation of very, very well-defined particles. A very important event in this is the proton transfer kinetics that lead to the formation of the hydrolysis of many of these trivalent ions. 

The pyrolysis temperature and the rate of addition are chosen such that about 50% of the acid chloride is recovered as 2-toluic acid after hydrolysis. Under these conditions only a small amount of benzyl chloride and polymeric material is formed in addition to benzocyclobutenone. The percentage of reactant conversion depends not only on the pyrolysis temperature, but also on the pressure in the reactor and on the rate of reactant addition. It is advisable, therefore, to optimize the pyrolysis temperature in trial runs keeping the other variables constant. 

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