PROCESS FOR THE PRODUCTION OF 1,3-BUTADIENE FROM 1,3-BUTANEDIOL

Abstract

Process for the production of 1,3-butadiene comprising: feeding a mixture (a) comprising 1,3-butanediol and water to an evaporator, said water being present in an amount of greater than or equal to 5% by weight, preferably ranging from 10% by weight to 85% by weight, more preferably ranging from 15% by weight to 30% by weight, relative to the total weight of said mixture (a), to obtain: (b) a gaseous stream comprising 1,3-butanediol exiting from the top of said evaporator; and, optionally, (c) a blow-down stream exiting from the bottom of said evaporator; feeding said gaseous stream (b) to a first reactor containing at least one dehydration catalyst to obtain (d) a stream comprising alkenols, water and, optionally, impurities and/or unreacted 1,3-butanediol, exiting from said first reactor; optionally, feeding said stream (d) to a first purification section to obtain: (e) a stream comprising al-kenols, water, and, optionally, impurities; (f) a stream comprising water and, optionally, impurities and/or unreacted, 3-butanediol; and, optionally, (f) a stream comprising impurities; feeding said stream (d) or said stream (e) to a second reactor containing at least one dehydration catalyst to obtain (g) a stream comprising 1,3-butadiene, water and, optionally, impurities and/or unreacted alkenols, exiting from said second reactor; feeding said stream (g) to a second purification section to obtain: (h) a stream comprising pure 1,3-butadiene; (i) a stream comprising water and, optionally, unreacted alkenols; and, optionally, (1) a stream comprising impurities. Said 1,3-butadiene may advantageously be used as a monomer or intermediate in the production of elastomers and (co)polymers.

Claims

1. Process for the production of 1,3-butadiene comprising: feeding a mixture (a) comprising 1,3-butanediol and water to an evaporator, said water being present in an amount of greater than or equal to 5% by weight, relative to the total weight of said mixture (a), to obtain: (b) a gaseous stream comprising 1,3-butanediol exiting from the top of said evaporator; and, optionally (c) a blowdown stream exiting from the bottom of said evaporator; feeding said gaseous stream (b) to a first reactor containing at least one dehydration catalyst to obtain (d) a stream comprising alkenols, water and, optionally, impurities and/or unreacted 1,3-butanediol, exiting from said first reactor; optionally, feeding said stream (d) to a first purification section to obtain: (e) a stream comprising alkenols, water, and, optionally, impurities; (f) a stream comprising water and, optionally, impurities and/or unreacted 1,3-butanediol; and, optionally, (f′) a stream comprising impurities; feeding said stream (d) or said stream (e) to a second reactor containing at least one dehydration catalyst to obtain (g) a stream comprising 1,3-butadiene, water and, optionally, impurities and/or unreacted alkenols, exiting from said second reactor; feeding said stream (g) to a second purification section to obtain: (h) a stream comprising pure 1,3-butadiene; (i) a stream comprising water and, optionally, unreacted alkenols; and, optionally, (l) a stream comprising impurities.

2. Process for the production of 1,3-butadiene according to claim 1, in which said mixture (a) is derived from the fermentation of sugars obtained from biomass.

3. Process for the production of 1,3-butadiene according to claim 1, in which said mixture (a) is derived from the fermentation of sugars obtained from guayule or thistle, including discards, residues derived from said guayule and/or thistle or from the processing thereof.

4. Process for the production of 1,3-butadiene according to claim 1, in which said evaporator operates: at a temperature ranging from 95° C. to 300° C. and/or at a pressure ranging from 0.5 bara (bar absolute) to 5 bara (bar absolute)

5. Process for the production of 1,3-butadiene according to claim 1, in which said blowdown stream (c) exits from the evaporator at a flow rate such as to remove a quantity of mixture (a) fed to said evaporator ranging from 0.5% by weight to 5% by weight, relative to the total weight of said mixture (a) fed to the evaporator in one hour.

6. Process for the production of 1,3-butadiene according to claim 1, in which the catalyst contained in said first reactor is selected from cerium oxide (CeO.sub.2), aluminium oxide (γ-Al.sub.2O.sub.3), aluminium silicate (SiO.sub.2—Al.sub.2O.sub.3), sulfonated resins, ion-exchange resins, acidic earths, said catalysts optionally being supported on inert carriers.

7. Process for the production of 1,3-butadiene according to claim 1, in which said first reactor operates: at a temperature ranging from 190° C. to 450° C. and/or at a pressure ranging from 0.3 bara (bar absolute) to 2 bara (bar absolute)

8. Process for the production of 1,3-butadiene according to claim 1, in which the gaseous stream (b) is fed to said first reactor operating at a “Weight Hourly Space Velocity” (WHSV), which is at a ratio between the weight of the gaseous stream (b) fed in one hour and the weight of catalyst, said ratio being measured in h.sup.−1, ranging from 0.5 h.sup.−1 to 30 h.sup.−1.

9. Process for the production of 1,3-butadiene according to claim 1 , in which the catalyst contained in said second reactor is selected from aluminium oxide (γ-Al.sub.2O.sub.3), aluminium silicate (SiO.sub.2—Al.sub.2O.sub.3), aluminas, zeolites, sulfonated resins, ion-exchange resins, metal phosphates, ammonium phosphate, acidic earths said catalysts optionally being supported on inert carriers.

10. Process for the production of 1,3-butadiene according to claim 1, in which said second reactor operates: at a temperature ranging from 250° C. to 450° C; and/or at a pressure ranging from 0.3 bara (bar absolute) to 2 bara (bar absolute).

11. Process for the production of 1,3-butadiene according to claim 1, in which said stream (d) or said stream (e) is fed to said second reactor operating at a “Weight Hourly Space Velocity” (WHSV), which is at a ratio between the weight of said stream (d) or of said stream (e) fed in one hour and the weight of catalyst, said ratio being measured in h.sup.−1, ranging from 0.5 h.sup.−1 to 20 h.sup.−l .

12. Process for the production of 1,3-butadiene according to claim 1 comprising feeding a mixture comprising at least one alkenol selected from 2-buten-1-ol (crotyl alcohol), 3-buten-2-ol (methyl vinyl carbinol), 3-buten, said mixture being derived from the fermentation of sugars obtained from biomass, to said evaporator, and subsequently to said second reactor.

Description

EXAMPLE 1

[0089] The description of the present example makes reference to FIG. 1 shown below. Table 2 shows the results obtained in terms of conversion (C %), selectivity (S %) and yield (Y %), expressed by calculating the conversion of 1,3-butanediol (1,3-BDO) (C.sub.1,3-BDO), selectivity for alkenols (S.sub.i) and yield of alkenols (Y.sub.ALK) alkenol (ALK.) conversion (C.sub.ALK), selectivity for 1,3-butadiene (1,3-BDE) (S.sub.1,3-BDE) and yield of 1,3-butadiene (1,3-BDE) (Y.sub.1,3-BDF), according to the formulae shown below.

[00001]$C_{1,3-\mathrm{BDO}}=\frac{{\left({\mathrm{moles}}_{1,3-\mathrm{BDO}}\right)}_{\mathrm{in}}-{\left({\mathrm{moles}}_{1,3-\mathrm{BDO}}\right)}_{\mathrm{out}}}{{\left({\mathrm{moles}}_{1,3-\mathrm{BDO}}\right)}_{\mathrm{in}}}\times 100;$$S_i=\frac{{\mathrm{moles}}_{\mathrm{ALK}.}}{{\left({\mathrm{moles}}_{1,3-\mathrm{BDO}}\right)}_{\mathrm{in}}-{\left({\mathrm{moles}}_{1,3-\mathrm{BDO}}\right)}_{\mathrm{out}}}\times 100;$$C_{\mathrm{ALK}.}=\frac{{\left({\mathrm{moles}}_{\mathrm{ALK}.}\right)}_{\mathrm{in}}-{\left({\mathrm{moles}}_{\mathrm{ALK}.}\right)}_{\mathrm{out}}}{{\left({\mathrm{moles}}_{\mathrm{ALK}.}\right)}_{\mathrm{in}}}\times 100;$$S_{1,3-\mathrm{BDE}}=\frac{{\mathrm{moles}}_{1,3-\mathrm{BDE}}}{{\left({\mathrm{moles}}_{\mathrm{ALK}.}\right)}_{\mathrm{in}}-{\left({\mathrm{moles}}_{\mathrm{ALK}.}\right)}_{\mathrm{out}}}\times 100;$$Y_{\mathrm{ALK}.}=\frac{C_{1,3.Math..Math.\mathrm{BDO}}\times S_i}{100};$$Y_{1,3-\mathrm{BDE}}=\frac{C_{\mathrm{ALK}.}\times S_{1,3-\mathrm{BDE}}}{100}$$\mathrm{in}.Math..Math.\mathrm{which}.Math.\text{:}$${\left({\mathrm{moles}}_{1,3-\mathrm{BDO}}\right)}_{\mathrm{in}}=\mathrm{input}.Math..Math.\mathrm{moles}.Math..Math.\mathrm{of}.Math..Math.1,3-\mathrm{butanediol};$${\left({\mathrm{moles}}_{1,3-\mathrm{BDO}}\right)}_{\mathrm{out}}=\mathrm{output}.Math..Math.\mathrm{moles}.Math..Math.\mathrm{of}.Math..Math.1,3-\mathrm{butanediol};$${\mathrm{moles}}_{\mathrm{ALK}.}=\begin{array}{c}\mathrm{total}.Math..Math.\mathrm{moles}.Math..Math.\mathrm{of}.Math..Math.\mathrm{alkenols}.Math.[\mathrm{based}.Math..Math.\mathrm{on}.Math..Math.3.Math.\text{-}.Math.\mathrm{buten}.Math.\text{-}.Math.2.Math.\text{-}.Math.\mathrm{ol}\\ \left(\mathrm{methyl}.Math..Math.\mathrm{vinyl}.Math..Math.\mathrm{carbinol}\right).Math..Math.\mathrm{and}.Math..Math.2.Math.\text{-}.Math.\mathrm{buten}.Math.\text{-}.Math.1.Math.\text{-}.Math.\mathrm{ol}.Math.\\ \left(\mathrm{crotyl}.Math..Math.\mathrm{alcohol}\right)];\end{array}$${\left({\mathrm{moles}}_{\mathrm{ALK}.}\right)}_{\mathrm{in}}=\mathrm{input}.Math..Math.\mathrm{moles}.Math..Math.\mathrm{of}.Math..Math.\mathrm{alkenols};$${\left({\mathrm{moles}}_{\mathrm{ALK}.}\right)}_{\mathrm{out}}=\mathrm{output}.Math..Math.\mathrm{moles}.Math..Math.\mathrm{of}.Math..Math.\mathrm{alkenols};$${\mathrm{moles}}_{1,3-\mathrm{BDE}}=\mathrm{total}.Math..Math.\mathrm{moles}.Math..Math.\mathrm{of}.Math..Math.1,3.Math.\text{-}.Math.\mathrm{butadiene}.$

[0090] Table 3 shows the characterisation of the streams obtained, in which the weight percentages of the compound(s) are expressed relative to the total weight of the stream obtained, characterisation being carried out as described below.

(i) Preparation of Alkenols from a Mixture of 1,3-Butanediol

[0091] A mixture (a) comprising 1,3-butanediol and water having the following composition was used for this purpose: 17% by weight of water relative to the total weight of said mixture comprising 1,3-butanediol.

[0092] A first tubular reactor, with an internal diameter of 10 mm, was charged with 10 g of cerium oxide (CeO.sub.2 pellets of about 1 mm). Said first tubular reactor was heated with an electrical oven and the temperature inside the reactor was maintained at 400° C. during the test. The temperature of the evaporator was maintained at 250° C. during the test. The pressure inside said first tubular reactor and the evaporator was maintained at atmospheric pressure (1 bara). The outlet from said first reactor was connected to a first condenser operating at 15° C. in order to recover those products which are liquid at room temperature. The vent of the flask for collecting the condensed liquid was connected to a sampling system made up of a steel cylinder of a volume of 300 ml equipped with intercept valves at each of the two ends. The gas flowed through the steel cylinder and the outlet from the latter was connected to a volumetric meter which measured the quantity of gas which evolved.

[0093] The above-stated mixture (a) comprising 1,3-butanediol and water was fed to said evaporator operating under the above-stated conditions at a flow rate of 100 g/h, vaporised, and fed to said first reactor at a WHSV of 10 h.sup.−1, said first reactor operating under the above-stated conditions. On exiting from said first reactor, the stream (d) obtained, the composition of which is shown in Table 3, was condensed, weighed and analysed by gas chromatography. The gas which evolved was measured and likewise analysed by gas chromatography. Table 2 shows the obtained results.

(ii) Purification of [Stream (d)]

[0094] Stream (d) obtained as described above was subjected to a first purification by distillation for the purpose of removing unreacted 1,3-butanediol. It should be noted that the alkenols present in said stream (d) form azeotropic mixtures with water, for which reason they cannot be separated from water by simple distillation in such a manner as to obtain them in pure form.

[0095] Distillation was carried out at atmospheric pressure, adding 3,5-di-tert-4-butylhydroxytoluene (BHT) to said stream (d) present in a boiler so as to obtain a concentration of the same of about 200 ppm in said stream (d). Said distillation was carried out using a 40-tray Oldershaw column (2×20 tray sections), by charging said stream (d) into the boiler in a single portion and taking various top cuts on the basis of the recorded temperatures, so gradually concentrating the heavier components in the boiler. The distillation conditions (reflux ratio, boiler heating power, quantity of distillate taken) were varied as a function of the boiling temperatures of the species to be separated and the recorded top temperatures.

[0096] Table 1 shows the distillation conditions.

TABLE-US-00001 TABLE 1 Alkenol distillation conditions at atmospheric pressure [H.sub.2O] ΔT boiler ΔT top (% wt./ Density (° C.) (° C.) RR.sup.(1) wt.).sup.(2) (g/cm.sup.3) Charge — — — 11.8 — Fraction 1 101.3-103.0 56.0-84.5 100  11.3 0.84 Fraction 2 103.1-104.3 85.0-86.8 100-30  24.1 0.87 Fraction 3 104.9-113.6 86.4-87.1 30 25.2 0.87 Fraction 4 114.6-152.3 87.1-94.4 30-40 34.4 0.89 Fraction 5 154.3-167.9  93.6-119.4 40-60 31.3 0.90 Fraction 6 169.2-208.6 120.1-121.2 60-70 1.03 0.85 Fraction 7 208.6-210.8 121.2-130.1 70 1.35 0.85 Boiler — — — 0.029 — .sup.(1)reflux ratio; .sup.(2)% by weight of water relative to total weight of the fraction.

[0097] In particular: [0098] Fraction 1 (up to about 84° C.) corresponds to the light cut to be removed; [0099] Fraction 2 and Fraction 3 correspond to an azeotrope at T=86.5° C. -87° C. between the lowest-boiling alkenol, i.e. 3-buten-2-ol (methyl vinyl carbinol) and water (said azeotrope having the composition: 73% by weight 3-buten-2-ol: 25% by weight water); [0100] 2-buten-1-ol (crotyl alcohol in cis and trans forms) and a small proportion of 3-buten-1-ol (allyl carbinol) together with 35% by weight of water start to distil off in Fraction 4; [0101] water is exhausted in Fraction 5 and the temperature thus rises to about 120° C.; [0102] Fraction 6 and Fraction 7 correspond to 95% - 97% 2-buten-1-ol (crotyl alcohol). The above-stated distillation yields a stream (e), the composition of which is shown in Table 3 and which is fed to a second reactor operating as stated below.
(iii) Preparation of 1,3 Butadiene from Stream (e)

[0103] A second reactor was used for this purpose. Said second reactor had the same characteristics as the above-described first reactor in stage (i) but was charged with 3 grams of aluminium silicate (SiO.sub.2‘Al.sub.2O.sub.3). Stream (e) was fed, in vapour form, at a WHSV of 3.3 h.sup.−1 to said second reactor operating at atmospheric pressure (1 bara) and at a temperature of 300° C. On exiting from said second reactor, the stream (g) obtained, the composition of which is shown in Table 3, was condensed, weighed and analysed by gas chromatography. The gas which evolved was measured and likewise analysed by gas chromatography. Table 2 shows the obtained results.

TABLE-US-00002 TABLE 2 1st DEHYDRATION REACTOR 1,3-BDO conversion % mol 94% Selectivity for alkenols.sup.(1) % mol 85% Yield of alkenols.sup.(1) % mol 80% 2nd DEHYDRATION REACTOR Alkenol conversion.sup.(1) % mol 99% Selectivity for 1,3-BDE % mol 89% 1,3-BDE yield % mol 88% .sup.(1)based on 3-buten-2-ol (methyl vinyl carbinol) and 2-buten-1-ol (crotyl alcohol).

TABLE-US-00003 TABLE 3 STREAM COMPOUNDS (a) (d) (e) (g) (h) 1,3-Butadiene 0.0% 0.0% 0.0% 45.2% 99.8% 1,3-Butanediol 83.0% 4.9% 0.0% 0.0% 0.0% Water 17.0% 30.6% 39.2% 49.4% 0.0% Light compounds.sup.(2) 0.0% 7.5% 0.1% 2.3% 0.2% Alkenols 0.0% 53.3% 59.1% 0.0% 0.0% Medium-boiling 0.0% 2.3% 1.5% 1.2% 0.0% compounds.sup.(3) Heavy 0.0% 1.4% 0.1% 1.9% 0.0% compounds.sup.(4) .sup.(2)compounds lighter than the low-boiling alkenol, i.e. 3-buten-2-ol (methyl vinyl carbinol) (T.sub.BOILING = 97° C.), excluding 1,3-butadiene; .sup.(3)compounds lighter than the high-boiling alkenol, i.e. 2-buten-1-ol (crotyl alcohol) (T.sub.BOILING = 121.5° C.); heavier than the low-boiling alkenol, i.e. 3-buten-2-ol (methyl vinyl carbinol) (T.sub.BOILING = 97° C.), excluding 1,3-butadiene [includes the medium-boiling alkenol 3-buten-1-ol (allyl carbinol) (T.sub.BOILING = 113.5)]; .sup.(4)compounds heavier than the high-boiling alkenol, i.e. 2-buten-1-ol (crotyl alcohol) (T.sub.BOILING = 121.5° C.).