Methacrylic acid

Example 1

The following example is a reproduction of example 2 as published in WO2012/72697.

Glycerol was converted to acrolein over a catalyst bed with hydrogen used to lower the partial pressure of the reactants. A catalyst layer consisting of 56 g of a catalyst, 10 w % of W0₃ supported on ZrO₂ in grains of the size 20-30 mesh, was used. The inlet liquid stream consisted of 20 wt % of glycerol in water fed to the preheater at 0.3 g/min. A gas stream of 100 ml/min of hydrogen was also fed to the preheater. The liquid stream was preheated and vaporized, to 280° C., prior entering the reactor. The inlet of reactor was held at 300° C. and a pressure of 5 bar gauge was applied over reactor. The outlet stream was cooled down in a condenser and the water was condensed. The liquid stream was collected in a sample vessel, while the gas stream 11 was collected in a Tedlar gas bag. The liquid sample was analyzed with a GC equipped with FID and a WAX-column for hydrocarbons (propanol, propanal, propionic acid etc.). The gas sample was analyzed with a two channel GC equipped with TCD for analyzing CO, CO₂, ethene, ethane etc. Glycerol was converted to beyond the detection limit and acrolein was yielded in amounts above 80%. The production of hydroxyacetone was lowered to 5% while the yields of CO and CO₂ essentially the same. Further, some 10% propionaldehyde was formed as a side product.

Example 2

The following example is a reproduction of example 1 as published in US 2011/112330.

A Cesium salt of tungstophosphoric acid (CsPW) was used for a 20 wt % aqueous solution of glycerol in a fixed catalyst bed together with air. The fixed catalyst bed was heated at a temperature of 260° C. to 350° C. whereas the Feed gas had following composition in mol percent:glycerin:oxygen:nitrogen:water=4.2:2.2:8.1:85.5. GHSV was 2445 h⁻¹. Acrolein was obtained in 93.1% Yield

Example 3

The catalyst (Mo₁Pd_01.57e-4Bi_0.09Co_0.8Fe_0.2Al_0.123V_4.69e-3K_5.33e-3) was tested with a gas feed composition of nitrogen:oxygen:propylene:water in the ratio of 77:7.50:5.50:10 at 342° C., at a pressure of 15 psi, and a total flow of 130 cc/min. The reaction product showed a 99% conversion of propylene with a 98% selectivity for acrolein.

Example 4

The following synthesis was a reproduction of example 1 in EP 1460053

A ring-shaped catalyst having the following composition Mo:Bi:Co:Fe:Na:B:K:Si:O 12:1:0.6:7:0.1:0.2:0.1:18:X (wherein X is a value determined by oxidation degrees of the respective metal elements) was used. At 200° C. a mixed reaction raw gas composed of 8 mol % of propylene, 67 mol % of air and 25 mol % of steam was fed into the reaction tubes of a fixed bed multipipe type reactor from a top thereof such that the reaction raw gas was contacted with the catalyst for 3.5 seconds. In addition, the temperature of the niter was controlled so as to attain a propylene conversion rate of 98%. The Yield of acrolein was 92.5%.

Example 5

The following synthesis was a reproduction of example 1 in U.S. Pat. No. 6,388,129

Converting a gas mixture (modified air) consisting of 90% by volume of 0₂ and 10% by volume of N₂ and 79.7 mol/h of recycled gas having the composition of 87.7% by volume of propane were converted to obtain propene via oxydehydrogenation of propane.

The by this process obtained propene can be furthermore converted to Acrolein by a process as described in example 3 or example 4.

Example 6

The following synthesis was a reproduction of example 1 in US 2016/23995

Synthesis of the Catalyst with an Sb/Fe ratio of 0.6:

A 0.05M solution was prepared by dissolving 2.21 g of oxalic acid in 500 ml of water at 80° C. with stirring. Once dissolution was complete, 140.97 g of iron nitrate nonahydrate were added to the oxalic acid solution while maintaining the temperature at 80° C. After complete dissolution of the iron nitrate nonahydrate, 30.51 g of antimony(III) oxide were added. The resulting solution was left to evaporate while maintaining the temperature at 80° C., with stirring, until a viscous solution was obtained, which was then dried in ail oven at 120° C. for 72 hours. After drying, the product obtained was pressed in the form of pellets which were subsequently ground in order to obtain a pulverulent product comprising particles having a size of between 250 and 630 μm. These particles were then calcined under static air from ambient temperature up to 500° C. while observing a temperature rise gradient of 1° C./min and then a phase of maintenance at 500° C. for 8 hours. The catalyst was subsequently left in the oven until the temperature had returned to 50° C. A catalyst exhibiting an Sb/Fe ratio of 0.6 (i.e., x=0.6) was obtained.

5 g of the catalyst prepared were placed in a fixed bed reactor. The reaction was carried out with a 7.2% by weight aqueous allyl alcohol solution. The reactor was heated to 400° C. and then fed with reactants (allyl alcohol/02/NH₃) at atmospheric pressure. The contact time of the reactants with the catalyst was of the order of 0.1 sec. The reaction time was 5 hours. The products resulting from the reaction were analyzed after trapping at the reactor outlet in a bubbler maintained at low temperature (−4° C.). The liquid obtained was subsequently analyzed on a gas chromatograph equipped with a flame ionization detector. Allyl alcohol/O2/NH3 molar ratio: 1/1.6/0.4: Conversion of the allyl alcohol 87%, Yield: 17% Acrylonitrile, 52% acrolein, 5% acetaldehyde, 5% propionaldehyde, 1% acetonitrile.

Example 8

The following synthesis was a reproduction of example 1 in DE 755524

The experiments were run at an aldehyde-to-hydrogen ratio of 1:2 on a molar basis and at 5 bar operating pressure. An aqueous solution of 10 wt % acrolein and hydrogen was fed to a preheater, wherein the mixture was heated to about 150° C. The resulting mixed gaseous stream was then fed to a reactor comprising the catalyst (2 wt % Pd on Al₂O₃—and one where the Pd has been concentrated to the outermost surface of the catalyst (0.18 wt % Pd on Al₂O₃)). Full conversion of acrolein was observed. The selectivity to propionaldehyde was about 85%. Side products hydroxyacetone, CO and CO₂.

Example 12

In this example a catalyst containing Pd and Pb was used. The synthesis is based on example 1 as disclosed in U.S. Pat. No. 6,680,405.

In a 4 L reactor equipped with a condenser and a stirrer, 350 g of a catalyst (a calcium carbonate catalyst containing 5 wt % palladium, 1 wt % lead and 1 wt % iron) and a reaction liquid of 700 g of methacrolein and 1280 g of methanol were charged. The reaction was continued for 4 hours at a bath temperature of 80° C. and under pressure of 400 kPa*abs, while blowing air and nitrogen at rates of 4.77 Nl/min and 5.0 Nl/min, respectively, thereby to synthesize methyl methacrylate. The reaction product was collected and analyzed, and as a result, a conversion of methacrolein and a selectivity of methyl methacrylate were found to be 75.1% and 85.2%, respectively.

Example 13

In this example a catalyst containing Pd and Pb was used. The synthesis is based on example 1 as disclosed in US 2014/206897.

50.1 g of methacrolein is added to the reactor, along with 25.2 g of methanol (for a molar ratio of methanol to methacrolein of about 1.1). Roughly 1 g of catalyst (e.g. comprising 3 wt % palladium and 2 wt % lead on silica) is added to the solution. A stirrer is turned on, and the solution is heated to about 50° C. Oxygen flow is begun at about 6 milliliters per minute (mL/min). The reactor is open to atmospheric pressure. The reaction is continued for about 4 hours. This results in methacrolein conversion of about 50 percent, with selectivity to methyl methacrylate of about 90 percent.

Example 14

Preparation of aqueous slurry A1: In 105 g of ion-exchange water heated to 40° C., 38.2 g of cesium nitrate [CsNO₃], 12.8 g of 75 wt % orthophosphoric acid, and 12.2 g of 67.5 wt % nitric acid were dissolved to form a liquid α. Separately, 138 g of ammonium molybdate tetra hydrate [(NH₄)₆Mo₇O₂₄·4H₂O] was dissolved in 154 g of ion-exchange water heated to 40° C., followed by suspending 3.82 g of ammonium metavanadate [NH₄VO₃] therein to form liquid β. Liquid α was dropwise added to Liquid β while stirring and maintaining the temperatures of liquids α and β at 40° C. to obtain aqueous slurry A1. The atomic ratios of metal elements, i.e., phosphorus, molybdenum, vanadium and cesium contained in aqueous slurry A1 were 1.5, 12, 0.5 and 3.0, respectively, and thus the atomic ratio of cesium to molybdenum was 3.0:12.

Preparation of aqueous slurry B1: In 120 g of ion-exchange water heated to 40° C., 14.6 g of 75 wt % orthophosphoric acid and 13.9 g of 67.5 wt % nitric acid were dissolved to form liquid a. Separately, 158.2 g of ammonium molybdate tetrahydrate was dissolved in 176 g of ion-exchange water heated to 40° C., followed by suspending 4.37 g of ammonium metavanadate therein to form liquid b. Liquid a was dropwise added to liquid b while stirring and maintaining the temperatures of liquids a and b at 40° C. to obtain aqueous Slurry B1. The atomic ratios of the metal elements, i.e., phosphorus, molybdenum and vanadium contained in aqueous slurry B1 were 1.5, 12 and 0.5, respectively, and thus the atomic ratio of cesium to molybdenum was 0:12.

Preparation of aqueous slurry M1: The whole quantity of aqueous slurry B1 was mixed with the whole quantity of aqueous slurry A, and then the mixture was stirred in a closed vessel at 120° C. for 5 hours. Then, to the mixture, the suspension of 10.2 g of antimony trioxide [Sb₂O₃] and 10.1 g of copper nitrate trihydrate [Cu(NO₃)₂, 3H₂O] in 23.4 g of ion-exchange water was added, and the mixture was further stirred in the closed vessel at 120° C. for 5 hours to obtain aqueous slurry M1. The aqueous slurry M1 was dried by heating it in an air at 135° C. to evaporate water therefrom. To 100 parts by weight of the dried product, 4 parts by weight of ceramic fiber, 17 parts by weight of ammonium nitrate and 7.5 parts by weight of ion-exchange water were added, and the mixture was kneaded and extrusion-molded into cylinders each having a diameter of 5 mm and a height of 6 mm. The molded cylinders were dried at 90° C. and a relative humidity of 30% for 3 hours and then calcined by maintaining them in an air stream at 390° C. for 4 hours and then in a nitrogen stream at 435° C. for 4 hours to obtain the catalyst. The catalyst comprised a heteropolyacid compound, and the atomic ratios of the metal elements other than oxygen, i.e., phosphorus, molybdenum, vanadium, antimony, copper and cesium contained in the heteropolyacid compound were 1.5:12:0.5:0.5:0.3:1.4, respectively, and thus the atomic ratio of cesium to molybdenum was 1.4:12.

9 g of the catalyst, synthesized as described before were charged into a glass micro-reactor having an inner diameter of 16 mm, and a starting gas composed of 4 vol % of methacrolein, 12 vol % of molecular oxygen, 17 vol % of water vapor and 67 vol % of nitrogen, prepared by mixing methacrolein, air, steam and nitrogen, was fed to the reactor at a space velocity of 670 h⁻¹, and a reaction was carried out at a furnace temperature (the temperature of a furnace used for heating the micro-reactor) of 355° C. for one hour. Then, the starting gas having the same composition as above was fed to the micro-reactor at the same space velocity as above, and the reaction was re-started at a furnace temperature of 280° C. After carrying out the reaction for 1 hour from the re-start of the reaction, an exit gas (a gas after reaction) was sampled and analyzed by gas chromatography, and a conversion of methacrolein (percent), a selectivity of 80% to methacrylic acid (percent) and a yield of 77% methacrylic acid were obtained at 96% conversion.

Example 11

In this example a catalyst containing Ni and Au was used.

Catalyst carrier synthesis: In a beaker 21.36 g Mg(NO₃)₂*6 H₂O, 31.21 g Al(NO3)3*9 H₂O are dissolved by stirring in 41.85 g water. 1.57 g 60% HNO₃ were added while stirring. 166.67 g Silicasol (Köstrosol 1530AS, 30 w % Si0₂, particle size: 15 nm) are placed in a 500 mL three necked flask and cooled to 15° C. while stirring. 2.57 g 60% HNO₃ were added slowly to this under vigorous stirring. At 15° C. the nitrate solution prepared before is added within 45 min to the solution. On complete addition the mixture is heated within 30 min to 50° C. and aged for 24 h (while stirring) at this temperature. Afterwards this mixture is spray dried at 130° C. The dried powder, (spherical particles with an average particle size of 60 μm) is heated in thin layers within 2 h to 300° C., kept for 3 h at 300° C., heated within 2 h to 600° C. and finally kept at this temperature for additional 3 h.

Metal & nobel metal impregnation of catalyst carrier: A suspension of 10 g carrier prepared before is mixed with 33.3 g water and heated to 90° C. It is kept for 15 min at this temperature, subsequently a 90° C. preheated solution of HAuCl₄*3 H₂O (205 mg) and Ni(NO₃)₂*6 H₂O (567 mg, 1.95 mmol) in 8.3 g water is added and the mixture is stirred afterwards for 30 min at 90° C. After cooling to room temperature # the mixture is filtered and washed six times with each 50 mL water. The resulting material was dried 10 h at 105° C. and carefully grinded afterwards. Finally the material is heated within 1 h from 18 to 450° C. to be kept at this temperature for 5 h.

Continuous conversion of Methacrolein to MMA/MAS: The pH-Value of a feed containing 42.5 wt % solution of methacrolein in MMA is adjusted to 7 by addition of a solution of NaOH in MeOH. The feed is added continuously to a stirred and gasified (with air) tank reactor at 10 bar pressure and 80° C. The reactor was charged before with 20 g Gold-Nickel-catalyst as prepared before. Additionally to the feed of MeOH and Methacrolein a second feed with 1 wt % NaOH in MeOH is continuously added to the reactor to keep the pH at 7.0. The reactor was operated at constant volume level and excess of volume was continuously removed via a filter, to keep the catalyst inside the reactor. After 2000 h TOS the catalyst had still a conversion of 73.8 wt % Methacrolein at a selectivity of 95.5% to MMA. Methacrylic acid is made additionally with a selectivity of 1%.