Acetic acid conversion

Although 21-acetoxy-17a-hydroxy-20-ketopregnanes are stable to zinc in refluxing acetic acid, conversion of the keto group to its semicarbazone results in removal of the 21-acetoxyl function under these conditions... 

Similar acetic acid conversions and higher acid yield distributions using ruthenium(IV) oxide in combination with methyl iodide, ethyl iodide and hydrogen iodide as the added iodide promoter under comparable conditions. This is consistent with these different starting materials ultimately forming the same catalytically active species. 

Other bimetallic systems have been investigated. An Fe-Co-based catalyst [266] exhibits high activity (achieving complete acetic acid conversion at 400 °C), high H2 selectivity and good stability. 

During the first 2h of reaction, a decrease in AcOH conversion (from 48 to 43 %) for benzene acetylation at 523 K with an increase in selectivity to the monoacetylated product (from 80 to 90%) can be observed. The only problem involves the low catalyst activity 1.5 mmolh 1g 1 of acetophenone, which corresponds to a TOF value of 2.2 h-1. This means that less than 0.2 g of this acetylated arene can be produced per hour and per gram of catalyst under the operating conditions (i.e. 10 times less than in the liquid phase acetylation of anisole with AA). The kinetic study of the reaction shows an increase in the selectivity with the substrate/acetic acid ratio, but no increase in yield, an increase in acetic acid conversion with the reaction temperature with a significant decrease in selectivity due to a greater formation of diacetylated products.[62,63] HFAU and RE-FAU zeolites do... 

When 7-aeyl-7 -reserpine derivatives (XV) are refluxed in dilute methanol with a few drops of acetic acid, conversion into the corresponding oxindole (XIX) with concomitant formation of the five-membered spiro-ring C takes place. Under these conditions, also, carbon... 

One version of the gas phase process was developed by National Distillers Products (now Quantum Chemical) in the USA and another independently in Germany by Bayer together with Hoechst. In both versions, ethylene is reacted with acetic acid and oxygen on a palladium-containing fixed-bed catalyst at 5-10 bar and 175-200°C to form vinyl acetate and water. The explosion limit restricts the O2 content in the feed mixture so that the ethylene conversion is relatively small ( 10%). The acetic acid conversion is 20-35% with selectivi-ties to vinyl acetate of up to 94% (based on C2H4) and about 98-99% (based on AcOH). The most important side reaction of this process is the total oxidation of ethylene to carbon dioxide and water. Other by-products are acetaldehyde, ethyl acetate and heavy ends. After a multistep distillation the vinyl acetate purity is 99.9% with traces of methyl acetate and ethyl acetate that do not affect the subsequent use in polymerization. 

See insulin. (10) Miscellaneous reactions, e.g., oxidation of pentaerythritol to tris(hydroxymethyl)acetic acid conversion of the sulfur in gypsum to elemental sulfur via hydrogen sulfide clean-up of oil spills. 

An important aspect is the oxidation of side-chain methyl to hydroxymethyl or aldehyde oxidation levels. The former can be achieved by reaction of the lithiated species with molecular oxygen, then qnenching with dimethyl sulfide in acetic acid. Conversion of methyl to the aldehyde oxidation level (see also 8.2) can be achieved by dibromination, then hydrolysis. ... 

Under neutral conditions and at 0 °C, indole reacts with a mixture of formaldehyde and dimethylamine by substitution at the indole nitrogen. This A-substitution may involve a low equilibrium concentration of the indolyl anion (20.4.1) or may be the result of reversible kinetic attack followed by loss of proton. In neutral solution at higher temperature or in acetic acid, conversion into the thermodynamically more stable... 

It is clear from the table that conversion of acetic acid in the esterification reaction increased with an increase in the temperature. Maximum esterification activity is observed at 1 ml h feed of 1 1 ethanol and acetic acid. Conversions as high as 90-95% were obtained with ethanol and n-propanol whereas conversion obtained with isopropanol was aroimd 55% only. 80-95%, conversions were also obtained with n-butanol, iso-butanol and sec-butanol. The sec-butanol and iso-propanol both have shown relatively low esterification activity compared to their normal alcohols. The very resemblance seen in the activity of isopropanol and sec-butanol may be due to the similar position of OH group attached to the secondary carbon atom in both the alcohols. The ease being more with the sec-butanol resulting in more esterification activity. 

Model oxygen containing compounds, or "oxygenates," having EHI s <1 produce excessive amounts of "coke", which leads to rapid catalyst deactivation (5)(0) using ZSM-5. Thus, as shown in Table I, initially complete acetic acid conversion declines to about 60% after only 3 hours on stream. At that point, the total hydrocarbon yield is less than 10 yrt,%, and the gasoline yield (0 +) is less than 7% (8). 

Table I Acetic Acid Conversion over ZSM-5 Fixed Bed Data...

Fig. 7.7 a) Acetic acid conversion and purities of MeOAc and A/ater in leaving product streams as a function of reboil ratio. The volumetric liquid hold-up on each reactive stage is set at 3 m. b) Acetic acid conversion as a function of the reboil ratio for various liquid hold-ups on each reactive stage... 

Fig. 7.23 Comparison of the acetic acid conversion obtained in the configurations shown in Fig. 7.22 as a function of the reflux ratio...

Ru-based and a Ni-based commercial catalyst in the second case. In both experiments, a complete acetic acid conversion was obtained. 

Fig. 4. Energy requirements of a distillation reactor (curve 1) and reboiler reactor (curve 2) in the production of butyl acetate for acetic acid conversion of 97%.

Methane-acetic acid conversion via direct catalytic conversion ... 

This example offers potential for acetic acid conversion from methane. The current market for acetic acid is valued at 4.5 billion. Exploitation of methane reserves can more safely occur following conversion by the easy transport of acetic acid, rather than gaseous methane. 

Solve the above problem for 90% acetic acid conversion and a fractional yield of methane of 0.08 and a reactor temperature of 800°C. 

Fig. 7.8 Simulated profiles of acetic acid conversion (%) in the fixed bed [9]...

Fig. 7.9 Simulated comparison of acetic acid conversion along axial direction between simulation and experimental data for Case 1 [9]...

Using a Pd-MR can give a rather high acetic acid conversion, with 30-35% hydrogen recovery. The overall reaction system can be optimized by tuning the right amount of Ru-based catalyst and Ni-based catalyst [59]. 

In these experiments, the concentrations of reactants and products at the exit of the reactor were observed under steady state conditions for different liquid velocities and molar ratio of reactants in a temperature range of 298 - 363 K. Typical results are shown in Fig. 5.1 for acetic acid-methanol system. For acetic acid with butanol and maleic acid with methanol esterification the results are shown in Fig 5.2 and 5.3 respectively. From these data the conversion of acid as a function of liquid velocity was also evaluated for all the systems. For example, the acetic acid conversion obtained for esterification with methanol is presented in Fig. 5.4 and 5.5 for 318 and 328 K respectively. 

The model equations were solved for predicting the acetic acid conversion using appropriate kinetics for acetic acid -ethanol, acetic acid-butanol and maleic acid ethanol systems reported in Chapters 2, 3 and 4. Other parameters required for model predictions are summarized in Table 5.3. 

Figure 16.25 Catalyst loading in single reactive tray configuration versus achievable acetic acid conversion under different reflux ratios.

Fig. 8. 13 Acetic acid conversion to isobutene. (From A. J. Crisd, H. Dou, T. Prasomari, Y. Roman-Leshkov, Cascade reactions for the continuous and selective production of isobutene from bioderived acetic acid over zinc-zirconia catalysts, ACS Catalysis, 4 (2014) 4196—4200. Copyright 2014 American Chemical Society).

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