Formation Of Acrylic Acid Research Articles

ChemInform Abstract: Oxidation of Propane to Acrylic Acid on V2O5‐P2O5‐Based Catalysts

Abstract V 2 O 5 P 2 O 5 -based oxides were found to be effective as catalysts for the partial oxidation of propane, using gaseous oxygen as an oxidant. Acrylic acid was the sole product other than carbon oxides. The best results for the formation of acrylic acid are obtained with this Te/P/V atomic ratio; 0.10−0.15/1.15/1 oxide catalysts. The yield of acrylic acid attains 10.5 mol%. As the extent of the reaction increases, the selectivity steadily decreases, while the yield first increases and then attains a maximum at a propane conversion of about 50%. The rate of reaction increases with an increase in the concentrations of both oxygen and propane, while it remains almost unchanged with the addition of water vapor to the feed gas. On the other hand, for the formation of acrylic acid, higher concentrations of oxygen and water vapor, a lower concentration of propane, and a lower reaction temperature are found to be favorable.

The role of acrolein in allyl alcohol-induced lipid peroxidation and liver cell damage in mice

Male NMRI mice were fed a sucrose diet for 48 hr in order to reduce the hepatic glutathione content and to level off its diurnal variation. After administration of allyl alcohol (AA: 1.1 mmol/kg), hepatic glutathione (24.3 ± 7.0 nmol GSH/mg protein) was almost totally lost within the first 15min (<0.5 nmol GSH/mg protein). Subsequently, a massive lipid perioxidation was observed, i.e. the animals exhaled 414 ± 186 nmol ethane/kg/hr compared to 0.9 ± 0.8 of controls, and the hepatic TBA- reactive compounds had increased from 55 ± 16 pmol/mg protein in controls to 317 ± 163 after 1 hr. Concomitantly, a 40–45% loss of the polyunsaturated fatty acids (arachidonic and docosahexaenoic acid) in the liver lipids was observed. About 80% of the cytosolic alcohol dehydrogenase activity and about 50% of the microsomal P450-content were destroyed. In vivo-inhibition of alcohol dehydrogenase by pyrazole or induction of aldehyde dehydrogenase by phenobarbital abolished AA-induced liver damage as well as glutathione depletion and lipid peroxi- dation, while inhibition of aldehyde dehydrogenase by cyanamide made a subtoxic dose of AA (0.60 mmol/kg) highly toxic. These results strongly favour the importance of acrylic acid formation as an additional detoxification pathway. Enhanced hepatic levels of glutathione protected in vivo against the damaging effects of AA. Depletion of the liver glutathione content by phorone or diethylmaleate alone caused marginally enhanced lipid peroxidation (phorone) but no liver cell damage. Mono- oxygenase inhibitors (metyrapone, diethyldithiocarbamate, α-naphthoflavone) or an inducer (benz( a)pyrene) did not affect AA-induced toxicity. The ferric iron chelator desferoxamine- methanesulfonate prevented AA-induced lipid peroxidation and liver cell damage in vivo. In vitro, acrolein alone failed to initiate lipid peroxidation in soy bean phospholipid liposomes or in mouse liver microsomes. Thus, acrolein not only impairs the glutathione defense system but also directly destroys cellular proteins and evokes lipid peroxidation by an indirect iron-depending mechanism.

Selective oxidation of acrolein to acrylic acid by V2O5-P2O5 catalysts

V2O5P2O5 catalysts were found to be effective for the partial oxidation of acrolein to acrylic acid. The addition of phosphorus to V2O5 induces a large increase in the selectivity to acrylic acid, though it also induces a marked decrease in the oxidation activity. The best results for the formation of acrylic acid are obtained with the P/V atomic ratio = 1.2 catalyst. The selectivity to acid remains unchanged at 90 to 95 mol% up to the acrolein conversion of about 95%. More than 95 mol% of the produced acid was found to be acrylic acid. The selectivity of the P/V = 1.2 catalyst was higher than that of the MoO3V2O5 (Mo/V atomic ratio = 4.7) catalyst. B2O3, TeO2, Co3O4, and ZrO2 were added to the P/V = 1.2 system, but the selectivity was not improved. It is proposed that the phosphorus plays a role in suppressing the basic property of catalyst which contribute to the consecutive oxidation of acrylic acid. The effects of reaction variables, such as oxygen concentration, acrolein concentration, water vapor, on the activity and selectivity were also studied.

Oxidation of propane to acrylic acid on V 2O 5&P 2O 5-based catalysts

V 2O 5P 2O 5-based oxides were found to be effective as catalysts for the partial oxidation of propane, using gaseous oxygen as an oxidant. Acrylic acid was the sole product other than carbon oxides. The best results for the formation of acrylic acid are obtained with this Te/P/V atomic ratio; 0.10−0.15/1.15/1 oxide catalysts. The yield of acrylic acid attains 10.5 mol%. As the extent of the reaction increases, the selectivity steadily decreases, while the yield first increases and then attains a maximum at a propane conversion of about 50%. The rate of reaction increases with an increase in the concentrations of both oxygen and propane, while it remains almost unchanged with the addition of water vapor to the feed gas. On the other hand, for the formation of acrylic acid, higher concentrations of oxygen and water vapor, a lower concentration of propane, and a lower reaction temperature are found to be favorable.

Determination of rate equations of catalytic oxidation of propene to acrolein and acrylic acid in the gas phase

The kinetics of propene catalytic oxidation to acrolein and acrylic acid was studied in a flow-circulation reactor over a multicomponent oxide catalyst containing molybdenum, cobalt, nickel, iron, bismuth, and potassium. The rate equations were found for the total formation of acrolein and acrylic acid.

Production of Higher Alcohols and Short Chain Fatty Acids by Different Yeasts Used in Rum Fermentations

ABSTRACTThe production of higher alcohols and short chain fatty acids by yeasts used in rum fermentations was greater by the Saccharomyces strains than by those belonging to the Schizosaccharomyces genus. There were also qualitative differences between these two genera. Among the organic acids of the raw material, citric acid and cisaconitic acid constitute a special feature of the composition of the resulting rums. Their presence entails the abundant production of biomass. Citric acid alone induced acrylic acid formation by strains of two species among the three studied.

Vapour phase oxidation of acrolein to acrylic acid on mixed oxides as catalyst

The vapour phase oxidation of propylene to acrylic acid is generally carried out by a two step process, involving acrolein as an intermediate. In this work, the kinetic data on the second step of the process, i.e. the oxidation of acrolein to acrylic acid were obtained using a catalyst containing oxides of antimony, nickel and molybdenum. The effects of temperature, space time and concentration of acrolein and oxygen on the yield and conversion to acrylic acid were studied, and the most suitable conditions were determined for the process. Carbon dioxide was the major by product in the reaction. The formation of acrylic acid and carbon dioxide were correlated by suitable rate expressions.

Vapour phase oxidation of acrolein to acrylic acid on mixed oxides as catalyst

AbstractThe vapour phase oxidation of propylene to acrylic acid is generally carried out by a two step process, involving acrolein as an intermediate. In this work, the kinetic data on the second step of the process, i.e. the oxidation of acrolein to acrylic acid were obtained using a catalyst containing oxides of antimony, nickel and molybdenum. The effects of temperature, space time and concentration of acrolein and oxygen on the yield and conversion to acrylic acid were studied, and the most suitable conditions were determined for the process. Carbon dioxide was the major by product in the reaction. The formation of acrylic acid and carbon dioxide were correlated by suitable rate expressions.

A note on the influence of water vapour in the oxidation of propene to acrylic acid on a mixed oxide catalyst

The interaction of propene and H218O in the absence of gaseous oxygen was studied on a Mo−W−Sn−Te−O catalyst prepared for the production of acrylic acid. The flow reactor working at low pressures was placed close to the ion source of the mass spectrometer. It was found that the formation of an acrolein-lattice oxygen complex is an intermediate step in the formation of acrylic acid. The acrolein type complex reacts further with oxygen from water to give acrylic acid. Evidence was found for the formation of unstable products from water on mixed oxide catalysts of molybdate type.

The thermal degradation of poly(oxycarbonylethylene) (poly‐β‐propiolactone)

AbstractThe thermal degradation of poly(oxycarbonylethylene) (poly‐β‐propiolactone) has been investigated within a temperature range of 180–220°C and under various pressures. The degradation begins with a considerable decrease in molecular weight, followed by an accelerating formation of acrylic acid. The reaction involves the following steps: Random chain scission of polymer chains by typical ester pyrolysis with the formation of fragments one of which containing a carboxylic group the other one a CC‐double bond at the chain end (Eq. (1)). Formation of the volatile acrylic acid by scissions at the chain end, the amount of acrylic acid or the weight‐loss increasing with the number of fragmentations (Eq. (2)). Autocatalysed acidic cleavage of the polyester fragments into an α,β‐unsaturated ester and an acid as shown with low molecular model compounds (Eq. (8)). Substitution of the labile α‐hydrogen atoms in poly(oxycarbonylethylene) by methyl groups—such as in poly(oxycarbonyl‐1,1‐dimethylethylene)—reduces the rate of degradation drastically. This observation together with the results obtained in the pyrolysis of the low‐molecular model compounds, ethyl β‐acetoxypropionate and β‐acetoxypropionic acid, support the postulated mechanism.

Vapor Phase Oxidation of Propylene over Metallic Palladium in the Presence of Water

Acrolein and acrylic acid were formed in rairly high yield by the oxidation of propylene over metallic palladium supported on active charcoal or silica gel in the presence of steam at 100∼160°C. This reaction temperature is much lower than that for transition metal oxide catalysts.Besides acrolein and acrylic acid, carbon dioxide was formed. Acrylic acid anal carbon dioxide increased with reaction temperature, while the formation of acrolein reached maximum at 140°C. The rate of formation of acrolein and acrylic acid linearly increased with increase in steem pressure, whereas that of carbon dioxide had little relationship to steam pressure. The rate of achrolein (plus acrylic acid) formation was found to be represented by the following equation:It was suggested that carbon dioxide and acrolein were formed on different sites of catalyst surface.

Preparation of Acrylic Acid

A modified Reppe process for manufacturing acrylic acid (AA) under normal pressure and another method by hydrolysis of acrylonitrile (AN) are reported. I. Modified Reppe process using normal pressure under continous operation.Thier reaction is affected by various factors such as molar ratio, acetylene feeding velocity, reaction temperature, circulation velocity, viz, agitating velocity and so on.The best reaction conditions were as follows : Acetylene feeding velocity : 200 l/hr.Reaction temperature : 40°CCirculation velocity for the reaction mixture : 1, 800 l/hr.Reaction composition : AA/Solvent=1/1 (wt.) Solvents : MEK, MIBKThe yield was about 80%.II. AN hydrolysisThe follwing reactions for conversion of AN into AA were studied.CH2=CHCN+H2SO4+H2O→CH2=CHCONH2·H2SO4CH2=CHCONH2·H2SO4 +H2O→CH2=CHCOOH + NH4HSO41. The first step reaction (formation of acrylamide).AN/sulfuric acid/water=1/1.5/4 (molar ratio) was employed at 12°C for 5 hrs with strring.The yield was about 95%.2. The second step reaction (formation of AA) The hydrolysis of acrylamide was effected by using 6 mol suplementary water per mol of acrylamide at 100°C for 2 hrs with stirring.Over-all yield of AA was about 850.3. KineticsThe apparent activation energy for the hydrolysis of AN was about 11.3 kcal/mol and the reaction was found to be second order in the concentrations of AN and water.