Biomass-derived methyl methacrylate and corresponding manufacturing method, uses and polymers

Abstract

The invention relates to methyl methacrylate characterized in that at least one portion of the carbons thereof is biologically sourced and, more specifically, in that it contains between 0.210.sup.10 and 1.210.sup.10 wt.-% of .sup.14C in relation to total carbon weight according to the ASTM D6866 standard. The preparation method uses acetone cyanohydrin as a raw material, the acetone cyanohydrin being obtained by condensing cyanohydric acid on acetone, and the methyl methacrylate is prepared using a process involving the addition of methanol. According to the invention, at least one from among the acetone, cyanohydric acid and methanol is obtained by a reaction or series of reactions involving the biomass.

Claims

1. A method for the manufacture methyl methacrylate, comprising: a) condensing hydrocyanic acid with acetone to form acetone cyanohydrin, and b) introducing methanol to form methyl methacrylate, wherein the acetone, hydrocyanic acid and methanol are obtained by a reaction or a succession of reactions starting from biomass, and wherein the methyl methacrylate comprises 1.210.sup.10% by mass of .sup.14C relative to the total mass of carbon according to standard ASTM D6866, wherein the acetone is obtained by acetobutylic fermentation of C.sub.6 and C.sub.5 sugars, resulting in an acetone-butanol mixture, where appropriate with ethanol, and separating the acetone by distillation or by membrane separation or by separation on silicalite, or other means of separation, wherein the hydrocyanic acid is obtained by ammoxidation of methane, wherein the methane is obtained by fermentation, in the absence of oxygen, of animal and/or plant organic materials, resulting in a biogas mainly composed of methane and carbon dioxide, wherein the carbon dioxide is removed by washing the biogas with a basic aqueous solution of sodium hydroxide, potassium hydroxide or amine, or else with water under pressure, or by absorption in a solvent, and wherein the methanol is obtained by pyrolysis of wood or by gasification of any materials of animal or plant origin, resulting in a syngas mainly composed of carbon monoxide and hydrogen which is reacted with water, or by fermentation starting from plant crops giving fermentable products and therefore alcohol.

2. The method as claimed in claim 1, wherein: in a first step, hydrocyanic acid is condensed with acetone via a basic catalysis in order to obtain acetone cyanohydrin; in a second step; the acetone cyanohydrin is reacted in a concentrated sulfuric medium in order to obtain -oxyisobutyramide monosulfate, which is converted to sulfuric methacrylamide under the action of the heat of the reaction which is highly exothermic; in a third step, the methacrylamide is hydrolyzed and esterified with methanol so as to form methyl methacrylate and ammonium hydrogen sulfate, and the desired starting material is recovered.

3. The method as claimed in claim 1, wherein: in a first step, hydrocyanic acid is condensed with acetone via a basic catalysis in order to obtain acetone cyanohydrin; in a second step, the acetone cyanohydrin is reacted with methanol in order to obtain methyl hydroxymethacrylate; in a third step, the methyl hydroxymethacrylate is dehydrated so as to recover the desired starting material.

4. The method as claimed in claim 1, wherein the syngas for preparing the methanol is obtained from the residual liquor from the manufacture and bleaching of cellulosic pulps.

Description

EXAMPLE 1: MANUFACTURE OF ACETONE FROM WHEAT STRAW BY ENZYME HYDROLYSIS FOLLOWED BY ACETOBUTYLIC FERMENTATION

(1) The procedure is carried out as described in the Revue de l'Institut Franais de Ptrole [French Petroleum Institute Review], vol. 36, No. 3, May-June 1981, pages 339-347.

(2) The wheat straw is shredded in a shredder and then the shredded straw is ground in a hammermill. This is followed by treatment with acid at a low concentration at a temperature of 100 C. for approximately 1 hour.

(3) After neutralizing the acid, the medium is brought to a pH in the region of 5, which is required for enzyme hydrolysis.

(4) A cellulose solution is prepared in the presence of nutritive elements in fermenters in series, the culturing of the microorganism Trichoderma reesi being carried out in the first fermenters starting from previously ground straw, and cellulose being produced in the subsequent fermenters. The desired enzyme solution is separated from the content of the final fermenter by centrifugation and filtration.

(5) Enzyme hydrolysis of the above pretreated straw is carried out with the above enzyme solution in reactors mounted in series.

(6) After filtration, C.sub.6 and C.sub.5 sugar solutions are recovered. The filtrate which contains lignin is dried so as to serve as fuel.

(7) An acetobutylic fermentation is carried out on the above C.sub.6 and C.sub.5 sugar solutions using the microorganism Clostridium acetobutylicum under aseptic conditions.

(8) The fermentation comprises two successive phases, the first resulting in the production of acetic acid and butylic acid, and the second resulting in the production of acetone, butanol and ethanol in the following proportions by weight: 68% butanol; 29% acetone; and 3% ethanol.

(9) The acetone is separated by azeotropic distillation.

EXAMPLE 2: SYNTHESIS OF ACETONE CYANOHYDRIN (AC)

(10) For this batch synthesis, a 1-liter jacketed glass reactor is used, which is equipped with mechanical stirring and surmounted by a condenser. The temperature is controlled via a circulation of cold glycol-containing water in the jacket (cryostat).

(11) 69.5 g of pure HCN and 149.4 g of acetone previously obtained by fermentation according to example 1 (equimolar mixture) are introduced into the previously cooled reactor (approximately 0 C.). As soon as the mixture reaches the temperature of 0 C., 34 mg of diethylamine (DEA) catalyst are added. The temperature passes through a maximum of 18 C. within about 6 minutes and then stabilizes rapidly at around 0 C. Samples are taken manually (approximately 1 g) over time in order to monitor the amount of unreacted HCN. The free HCN is assayed according to the Charpentier-Volhard method based on the precipitation of cyanide CN.sup. ions, by means of an excess of N/10 silver nitrate solution and titration of the excess silver nitrate with an N/10 KSCN solution in the presence of an Fe(SO.sub.4).sub.3 indicator in solution. After reaction for 150 minutes, a mixture comprising 1.53% by weight of free HCN, i.e. 0.533 mol/l, is obtained, which is equivalent to 10.855 mol/l of HCN converted and a degree of conversion to acetone cyanohydrin of 95.32 mol %.

(12) The crude product is neutralized by adding excess sulfuric acid (neutralization of the basic catalyst) and then purified by vacuum distillation. The unconverted HCN and acetone are removed at the top (gradual vacuum from 760 to 30 mmHg and maximum temperature of approximately 100 C.).

EXAMPLE 3: SYNTHESIS OF ACETONE CYANOHYDRIN (AC)

(13) The preceding example is reproduced with 69.5 g of HCN resulting from the ammoxidation of methane originating from biogas and 149.4 g of acetone previously obtained by fermentation according to example 1. The target reaction temperature is 15 C. (an exothermic peak at 9 C. is observed for 9 minutes of reaction). The free HCN is monitored as in the preceding example. After reaction for 340 minutes, a mixture is obtained which comprises 1.20% by weight of free HCN, i.e. 0.418 mol/l, which is equivalent to 10.667 mol/l of HCN converted and a degree of conversion to acetone cyanohydrin of 96.23 mol %, After distillation of the reaction product according to the preceding example, acetone cyanohydrin purified to 99.0-99.5% by weight is obtained.

EXAMPLE 4: SYNTHESIS OF SULFURIC METHYACRYLAMIDE (MACRYD)

(14) Pure acetone cyanohydrin (AC) prepared according to the preceding examples (titer 99.06% by weight) and 100% sulfuric acid (H.sub.2SO.sub.4) containing approximately 400 ppm of phenothiazine (polymerization inhibitor) are used for the preparation of sulfuric methacrylamide.

(15) The acetone cyanohydrin amidation reaction is carried out in a micropilot unit. The micropilot unit is composed of a stirred jacketed glass mixing reactor R1, itself composed of 3 stages each having a volume of 120 ml, and cooled with thermostated water; each stage is separated by a perforated diaphragm and stirred with a mixing turbine; a piston flow jacketed glass precooking exchanger R1-2 having a volume of 60 ml and heated with oil; a second stirred jacketed glass mixing reactor R2 composed of 3 stages having a volume of 120 ml, i.e. a total of 360 ml, and cooled with thermostatic water; each stage is separated by a perforated diaphragm and stirred with a mixing turbine; a piston flow jacketed glass cooking exchanger R3 having a volume of 36 ml; and a final baffled piston flow jacketed glass cooking reactor R4 having a total volume of 240 ml and heated with oil.

(16) This cascade of reactors operates continuously. The reactants are injected using pumps. The acetone cyanohydrin is introduced continuously into each of the stages of the reactors R1 and R2, i.e. six points of introduction. The sulfuric acid is introduced continuously at the base of the reactor R1. The reaction temperatures in R1, in R1-2, in R2, in R3 and in R4 are, respectively: 85 C., 120 C., 90 C., 140 C. and 140 C. Only the residence time in the reactor R4 is critical. The relative proportion of acetone cyanohydrin injected into R1 and R2 is 70/30, with an equal distribution in each stage of the reactors.

(17) Two series of synthesis are carried out: H.sub.2SO.sub.4/AC molar ratio (MR)=1.30 total flow rate of AC: 426.33 g/h; flow rate of H.sub.2SO.sub.4: 632.98 g/h. H.sub.2SO.sub.4/AC molar ratio (MR)=1.25 total flow rate of AC: 433.54 g/h; flow rate of H.sub.2SO.sub.4: 618.93 g/h.

(18) After approximately three hours of normal operation, samples are taken from each stage of reaction for analyses.

(19) The percentages, by mass, of methacrylamide and methacrylic acid are determined by HPLC analyses after diluting the samples in a phosphate buffer medium.

(20) The yield of (sulfuric methacrylamide+methacrylic acid) is determined at the outlet of the reactor R4 on the basis of these analyses and relative to the inflowing AC: MR 1.30: yield 91.5 mol %; MR 1.25: yield 90.8 mol %.

(21) The waste (not quantified) consists mainly of carbon monoxide.

(22) The sulfuric methacrylamide obtained is used as it is for the synthesis of methyl methacrylate.

EXAMPLE 5: SYNTHESIS OF METHYL METHACRYLATE (MMA)

(23) The reaction for esterification of sulfuric methacrylamide with methanol is also carried out in a micropilot unit in continuous mode. Methanol originating from the reaction of a syngas obtained by gasification of black liquor is used. This second micropilot unit is composed of a 10-stage glass plate reactive column into which the sulfuric methacrylamide and a water-methanol mixture are injected countercurrentwise (reactive distillation). At the top, the reactive column is surmounted by a distillation column filled with multiknit packing and by its condenser. It makes it possible to obtain crude methyl methacrylate. At the base, a distiller makes it possible to collect residual liquor, a mixture of ammonium hydrogen sulfate, sulfuric acid and water. This residual liquor is stripped with steam so as to recover the maximum amount of volatile organic compounds. A guard tube makes it possible to maintain a level of liquid in the distiller.

(24) The sulfuric methacrylamide obtained in the preceding example (molar ratio 1.25, temperature approximately 130 C.) is introduced at the top of the column at a flow rate of 838.9 g/h (i.e. as AC equivalent 344 g/h). A methanol-water mixture (90-10% by weight) is introduced at two levels of the reactive column: at the base with a flow rate of 155.2 g/h, and at an intermediate point with a flow rate of 38.8 g/h (methanol/AC molar ratio: 1.35). The distiller is continuously stripped with live steam at a flow rate of 275.1 g/h (steam/AC molar ratio: 3.78 and total water/AC molar ratio: 4.05).

(25) A methanolic solution of stabilizers containing phenothiazine is introduced at the top of the reflux column (flow rate approximately 5 g/h).

(26) Using a timer, a crude methyl methacrylate reflux of 0.8 is maintained in the reactive column.

(27) Once the equilibrium has been reached (approximately 3 hours), the operating conditions are the following: distiller temperature: 125-130 C.; reactor temperature: 110-115 C.; reflux temperature: 87 C.

(28) At the outlet, 3 streams are recovered: the waste at the top of the condenser, the crude MMA at the top of the distillation column, and the residual liquor at the outlet of the distiller. The respective flow rates are the following: 5.4 l/h, 502.4 g/h and 811.6 g/h. Their titers, expressed as % by weight, are the following: waste: carbon monoxide 45%, dimethyl ether 40%, others 5%; crude MMA: MMA 61.8%, methanol 11.9%, water 22.3%, other light compounds 0.5%, other heavy compounds 3.5% (i.e. an esterification yield of 92.2 mol % expressed relative to the inflowing methacrylamide); residual liquor: ammonium hydrogen sulfate 58.5%, H.sub.2SO.sub.4 13.8%, H.sub.2O 23.4%, unconverted methacrylamide 0.35%, MMA 0.37%, methacrylic acid 0.43%, other compounds 3.15%.

(29) The crude MMA is purified in the following way: liquid-liquid extraction of the methanol with water; topping of the light compounds by vacuum distillation; topping of the heavy compounds by vacuum distillation.

(30) These three operations are preferably carried out continuously and the final purity of the methyl methacrylate is greater than 99.5% by weight.

EXAMPLE 6: MASS PRODUCTION OF PMMA BY A CONTINUOUS PROCESS

(31) A mixture containing 99.6% of methyl methacrylate of renewable origin obtained in example 5, 0.38% of n-dodecyl mercaptan and 0.02% of DTAC (1,1-di(tert-amylperoxy)cyclohexane) is continuously introduced, at 40 C., into a stirred reactor kept at 160 C. and at a pressure of 10 bar. The reactor is emptied continuously at a mass flow rate that is identical to the feed flow rate.

(32) The heat generated by the polymerization reaction is thus consumed by the introduction of the cold mixture and the emptying of the hot reaction mixture. For a reactor volume of one liter, a feed flow rate of 2 l/h makes it possible to obtain a monomer conversion of approximately 50 mol %. The reaction liquid constantly drawn off is then degassed so as to remove the excess methyl methacrylate in a continuously fed extruder provided with degassing wells. The polymer thus obtained at the outlet of the extruder then contains 99.5% of PMMA and 0.5% of residual monomer.

EXAMPLE 7: MANUFACTURE OF PMMA BY THE CAST SHEET METHOD

(33) A mixture containing 99.943% of methyl methacrylate obtained in example 5, 0.055% of azobisisobutyronitrile and 0.002% of terpinolene is degassed in a vacuum flask at an absolute pressure of 500 mbar at ambient temperature, kept under magnetic stirring for 20 minutes. This step makes it possible to evacuate the gases dissolved in the mixture. The mixture thus degassed is then introduced into a mold consisting of 2 glass plates of 10 mm separated by a PVC seal having a diameter of 4 mm, at ambient temperature. Pliers are used to obtain good leak-tightness of the whole. The mold is then slightly inclined and the air bubbles are driven out by squeezing the PVC seal at the highest point of the mold. The whole is then introduced into a ventilated oven. Cooking is then carried out at a temperature of 50 C. for 10 h, followed by post-cooking at 130 C. for 30 minutes. After cooking, the whole is cooled to ambient temperature. A PMMA sheet is finally obtained by dismantling the mold. The PMMA sheet contains 99% of PMMA and 1% of residual monomer.

EXAMPLE 8: MANUFACTURE OF PMMA BY THE SUSPENSION PROCESSPREPARATION OF A SUSPENDING AGENT

(34) 120 parts of a solution of sodium hydroxide (NaOH) at 40% by weight and 630 parts of deionized water are charged to a reactor provided with stirring. 250 parts of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) are slowly added to the reactor and then the pH is adjusted to between 7 and 8 with a small amount of AMPS. After sufficient sparging of the solution with nitrogen in order to remove oxygen, the reactor is heated to 50 C. and then 0.075 part of potassium persulfate and 0.025 part of sodium metabisulfite are added. The polymerization ends within 60 minutes. The solution obtained is then diluted with 4000 parts of deionized water in order to obtain a solution which has a dry residue at 160 C. of 5.5% by weight and a Brookfield viscosity of 4 Pa.Math.s measured at 25 C.

(35) The suspension polymerization of methyl methacrylate and ethyl acrylate is carried out in the presence of the suspending agent as obtained above.

(36) 193 parts of deionized water and 7 parts of solution previously obtained corresponding to 0.385 part of dry product are charged to a pressure-resistant stirred reactor. Oxygen is removed by sparging with nitrogen and the solution is heated to 80 C. 100 parts of a deoxygenated mixture composed of 96 parts of methyl methacrylate obtained, 4 parts of ethyl acrylate, 0.25 part of t-butylperoxy-2-ethylhexanoate and 0.25 part of butanethiol are then charged to the reactor. The reactor is then hermetically sealed, and the mixture is gradually heated to 110 C. over 120 minutes. The reactor is left at 110 C. for a further 15 minutes and is then cooled.

(37) The polymer, in the form of beads, is separated from the aqueous solution by centrifugation, washed with deionized water and dried in an oven at 80 C.

EXAMPLE 9: MANUFACTURE OF AN IMPACT ADDITIVE FOR PMMA

(38) The following procedure is used to prepare an impact modifier having several layers consisting of a hard core, an elastomeric soft layer and a hard crown.

(39) The ratio of the three layers is 35/45/20 with each polymer having a refractive index of between 1.46 and 15.

(40) The composition of the three layers is the following:

(41) Layer 1: 74.8/25/0.2 MMA/EA/Alma

(42) Layer 2: 83.5/15.5/1 BA/STY/Alma

(43) Layer 3: 95/5 MMA/EA

(44) With:

(45) MMA: methyl methacrylate

(46) EA: ethyl acrylate

(47) BA: butyl acrylate

(48) STY: styrene

(49) Alma: allyl methacrylate.

(50) A monomer load consisting of 14% of layer 1 emulsified in water with potassium dodecylbenzene sulfonate and potassium carbonate for controlling the pH is polymerized using potassium persulfate at 80 C. The remainder of the monomers of layer 1 (86%) are then added to the preformed emulsion and then polymerized using potassium persulfate at 80 C., while controlling the amount of surfactant added in order to avoid the formation of new particles.

(51) Layer 2 is then added and polymerized using potassium persulfate at 80 C., while controlling the amount of surfactant added in order to avoid the formation of new particles. Layer 3 is polymerized using potassium persulfate at 80 C., also while controlling the amount of surfactant added in order to avoid the formation of new particles.

(52) The latex obtained is then cooled and recovered by spray-drying. It can be used to increase the impact strength of PMMA by mixing, for example, in an extruder.