PROCESS FOR OBTAINING A RENEWABLE HYDROCARBON STREAM SUITABLE AS A COMPONENT OF GASOLINE FORMULATIONS, RENEWABLE HYDROCARBON STREAM, AND GASOLINE FORMULATION

Abstract

The invention relates to a process that comprises dehydration of by-products from ethanol production from sugar cane, by fluidized bed catalytic cracking, for obtaining a renewable hydrocarbon stream, preferably consisting primarily of olefins with 5 carbon atoms, for use in gasolines, and to the and to the hydrocarbon stream and gasoline formulations thus obtained.

Claims

1. Process for obtaining a renewable hydrocarbon stream suitable as a component of gasoline formulations, characterized in that it comprises: a dehydration reaction of a feed of by-products from ethanol production from sugar cane, using fluid catalytic cracking (FCC) in the presence of an acid catalyst, the dehydration reaction occurring at a temperature in the range 350-550 C. and a pressure in the range of from 0 kgf/cm.sup.2 (0 KPa) to 2 kgf/cm.sup.2 (196.13 KPa), and wherein the catalyst/feed ratio by weight is between 3 and 10.

2. Process according to claim 1, further comprising distillation of the liquid product obtained from the dehydration reaction at a temperature in the range of from 20 to 70 C., preferably from 20 to 50 C.

3. Process according to claim 2, further comprising obtaining a hydrocarbon stream consisting primarily of olefins with 5 carbon atoms.

4. Process according to claim 3, wherein the degree of conversion of the by-products from ethanol production from sugar cane into olefins with 5 carbons is in the range from 80 to 100%.

5. Process according to claim 2, wherein the liquid product obtained from the dehydration reaction is cooled before continuing to the distillation.

6. Process according to claim 1, wherein the by-product from ethanol production from sugar cane is fusel oil, and more preferably the isoamyl alcohol present therein.

7. Process according to claim 3, characterized in that the stream consisting primarily of olefins comprises a percentage of isoamylenes between 60 and 80%.

8. Process according to claim 1, wherein the temperature of the dehydration reaction is in the range 450-500 C.

9. Process according to claim 1, wherein the pressure of the dehydration reaction is in the range from 1 kgf/cm.sup.2 (98.07 KPa) to 1.8 kgf/cm.sup.2 (176.52 KPa).

10. Process according to claim 1, wherein the acid catalyst is alumina, silica-alumina, zeolite Y and/or mixtures of any or all thereof.

11. Process according to claim 1, characterized in that the catalyst/feed ratio by weight is between 4 and 8.

12. Process according to claim 1, characterized in that the degree of conversion of the by-product from ethanol production from sugar cane into olefins with 5 carbons is in the range from 90 to 100%.

13. Renewable hydrocarbon stream, obtained by the process as defined in claim 1.

14. Gasoline formulation, comprising the renewable hydrocarbon stream of claim 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0044] The present disclosure relates to a process for obtaining a renewable hydrocarbon stream for use in gasolines, using by-products from ethanol production from sugar cane as raw material.

[0045] In particular, this disclosure deals with a process for obtaining a renewable hydrocarbon stream, preferably by means of a dehydration reaction of a by-product from ethanol production from sugar cane, particularly fusel oil and, more preferably, isoamyl alcohol present therein, bearing in mind the availability of these by-products on a large scale in Brazil. Said process is based on cracking technology of the fluidized bed catalytic cracking type (fluid catalytic cracking, FCC), which allows continuous and prolonged operation of the process in the vapour phase, using existing refinery equipment (dispensing with the use of a dedicated reactor) for obtaining a hydrocarbon stream consisting primarily of light olefins containing 5 carbon atoms.

[0046] The fluidized bed catalytic cracking process can employ suitable, commercially available catalysts that preferably include pulverized acid catalysts and, more preferably, alumina, silica-alumina, zeolite Y and/or mixtures of any or all of these components. The catalyst/feed ratio used in said dehydration reaction, which corresponds to the flow rate by weight of the feed (isoamyl alcohol or fusel oil) and catalyst circulation, can vary between 3 and 10, preferably between 4 and 8.

[0047] The reaction can take place at temperatures in the range from 350 to 550 C., preferably between 450 and 500 C. The operating pressures for the reaction are those typical of a fluidized bed catalytic cracking process (FCC) and can vary between about 0 kgf/cm.sup.2 (0 KPa) and 2 kgf/cm.sup.2 (196.13 KPa), preferably between 1 kgf/cm.sup.2 (98.07 KPa) and 1.8 kgf/cm.sup.2 (176.52 KPa).

[0048] The aforementioned operating conditions are selected so as to promote maximum conversion of the by-products from ethanol production from sugar cane into hydrocarbons containing mainly branched olefins with 5 carbon atoms, also known as isoamylenes. At the same time the reaction conditions avoid the formation of by-products from cracking and condensation such as Liquefied Petroleum Gas (LPG) (3 and 4 carbon atoms) and aromatics, such as benzene, toluene and xylenes, which are secondary products of octane rating and have lower calorific value. In general, the values of the degree of conversion of isoamyl alcohol to olefins with 5 carbons are in the range from 80 to 100%, preferably between 90 and 100%, and give rise to a light naphtha of excellent quality.

[0049] The liquid product obtained from the dehydration reaction is preferably cooled (to prevent loss of the isoamylenes by evaporation) and then distilled at a temperature in the range from 20 to 70 C., preferably between 20 and 50 C., in a TBP (true boiling point) column to separate the naphtha cut. As mentioned, the degree of conversion of isoamyl alcohol is high, above 80%. This can give as the final result, in addition to other by-products, a stream with a percentage of isoamylenes from 60 to 80% w/w, a high octane rating and stability compatible with the values observed for automotive gasolines. Furthermore, the content of sulphur and of nitrogen compounds present in the product derived from fusel oil is compatible for various segments of gasoline, including products that require low contents of impurities.

[0050] Therefore, compared to other processes for biomass conversion, dehydration of isoamyl alcohol is superior in maximizing the yield of the desired distillation range, and in avoiding the presence of oxygenates in the final fuel.

[0051] The following examples illustrate various embodiments of the present invention.

EXAMPLES

Example 1Production of Streams of Isoamylenes at the Pilot Scale

[0052] Preliminary tests for assessing the operating conditions of the FCC were carried out in a circulating pilot unit. The pilot unit was equipped with an adiabatic riser with a length of 1 m and an isothermal rectifier and a regenerator with temperature controlled by electric heating. The catalyst inventory of the unit was 2 kg and the flow rate of feed was 1 kg/h. The catalyst used was Ecat 1, a pulverized catalyst containing zeolite Y, used in a Petrobras commercial FCC unit in the cracking of gas oil. Table I presents the composition of the Ecat 1 catalyst (and Ecat 2, referred to further below), along with the specific area of the catalyst.

TABLE-US-00001 TABLE I Composition and specific areas of Ecat 1 and Ecat 2. Parameters ECAT 1 ECAT2 Specific Area m.sup.2/g 153 159.2 Al.sub.2O.sub.3, % w/w 41.8 43.2 Na, % w/w 0.33 0.23 Re.sub.2O.sub.3, % w/w 3.28 2.59 V, mg/kg 1284 544 Ni, mg/kg 1292 1053 P.sub.2O.sub.5, % w/w 1.00 0.75 Zeolite Y content 40% 40%

[0053] A feed of isoamyl alcohol (IAA) of petrochemical origin was used for studying the effect of the operating conditions, and the fusel oil used in run 3 was supplied by an ethanol distillery.

[0054] Table II presents a summary of the operating conditions of the pilot unit and of the yields of isoamylenes, including the cracking reaction temperature (TRX), and the catalyst to feed (oil) ratio (CTO). The operating conditions were selected so as to optimize the conversion of IAA, forming isoamylenes by dehydration, and at the same time minimize the formation of products with secondary octane rating and lower calorific value. Assessment of the processing of fusel oil was only conducted at the pilot scale, with a focus on assessing a lower-cost raw material. The fusel oil used in run 3 contained, based on dry matter, 76% w/w IAA (71% 3-methyl-1-butanol and 5% 2-methyl-1-butanol), 6% w/w butanols and 16% w/w ethanol. Overall, the fusel oil contained 17% w/w of water, resulting in lower yield of isoamylenes and higher yield of water compared to the IAA feed (run 1 vs run 3Table II). To generate a sufficient volume of liquid product, runs lasting 3 hours were carried out. The liquid product was collected in a vessel cooled with dry ice (to prevent loss of the isoamylenes by evaporation) and then distilled in a TBP column to separate the naphtha cut (initial boiling point [IBP]=70 C.), generating a sample of approximately 1 L, sufficient for complete characterization.

TABLE-US-00002 TABLE II Experimental conditions of the tests for dehydration of isoamyl alcohol in the pilot unit. Parameters Run 1 Run 2 Run 3 Feed IAA 99% IAA 99% Fusel oil fossil fossil Catalyst Ecat 1 Ecat 1 Ecat 1 TRX, C. 350 450 350 T. regenerator, C 600 600 600 CTO 7.1 7.3 8.4 Conversion IAA, % w/w 88.6 99.0 90.6 Yields, % w/w: Isoamylenes 44.4 49.5 29.1 Unreacted alcohol 11.4 1.0 9.4 Aromatics 0.2 0.7 0.5 Other liquid HCs 20.8 23.3 15.6 Water 18.9 20.9 38.3 Gas 2.5 3.5 5.5 Coke 1.7 1.1 1.6

[0055] Table III presents the data for characterization of the products generated in the pilot unit after distillation, including the lower calorific value (LCV) and the higher calorific value (HCV), and composition measured by gas chromatography (GC). The ASTM testing method reference for each parameter is included in brackets in the first column of the table.

[0056] It can be seen from Table III that all the cuts are light enough, with low density and high volatility (measured by RVPReid vapour pressure), showing that the process generates a stream with properties compatible with those of gasolines.

[0057] Regarding the energy content, it is observed that the products derived from processing the 99% fossil IAA had a lower calorific value (LCV) of about 44.3 MJ/kg, which is an excellent value, suitable for special gasoline formulations. The LCV of the product derived from the processing of fusel oil was approximately 2.3% less than that of the products derived from IAA, and this reflects the presence of the relatively high ethanol content (4.3% w/w) recovered in distillation. It should be emphasized that processing of fusel oil proved promising, as the negative impact observed on the LCV of the TBP cut can be corrected by adjusting the final boiling point (FBP) of the distillation cut (for example, 50 C.), which eliminates the presence of ethanol (boiling point [BP]=78 C.).

TABLE-US-00003 TABLE III Data for characterization of the TBP distillation cuts (IBP - 70 C.) of the products from dehydration of 99% fossil IAA (runs 1 and 2) and of fusel oil (run 3) in the pilot unit. Results Product Product Product from run 1 from run 2 from run 3 Vapour pressure @ 37.8 C. 115.3 117.6 129.5 (D5191), kPa Density @ 20 C. (D4052) 0.6540 0.6538 0.6693 FBP distillation (D86), C. <70 <70 <70 Induction period (D525), min 175 66 61 (>1.200.sup.i) (>1.200.sup.i) (>1.200.sup.i) Potential gum (D873) Not washed, mg/100 mL 12.5 26.0 30.0 Washed, mg/100 mL 8.5 28.0 Actual gum (D381) Not washed, mg/100 mL <0.5 2.0 <0.5 Washed, mg/100 mL <0.5 <0.5 HCV (D4809), MJ/kg 47.581 47.432 46.369 LCV (D4809), MJ/kg 44.419 44.339 43.271 Composition by GC (N2377) Saturates, % w/w 21.4 9.5 10.9 Olefins, % w/w 78.1 90.4 84.4 Aromatics, % w/w 0.1 0.0 0.2 Oxygenates, % w/w 0.0 0.1 4.4 Isoamylenes content, % w/w 66.2 72.2 68.1 Benzene, % w/w 0.1 0.0 0.1 H, % w/w (N 2377).sup.ii 14.9 14.6 14.6 C, % w/w (N 2377).sup.ii 85.1 85.4 83.9 O, % w/w (N 2377).sup.ii 0.0 0.0 1.5 Total sulphur (D7039), 20.4 mg/kg Total nitrogen (D5762), 8.7 mg/kg RON (D2699) 99.4.sup.iii ND.sup.iii ND.sup.iii (99.6.sup.iv) (99.2.sup.v) (101.0.sup.iv) .sup.iValue of IP for mixture of 10% w/w component/90% w/w alkylated product (IP alkylated product > 1200 min) .sup.iiCalculated from data on composition by GC .sup.iiiRON of the pure sample. Sample very volatile, irregular combustion .sup.ivRON value for mixture of 10% w/w component/90% w/w alkylated product (RON alkylated product = 98.5) .sup.vRON value for mixture of 10% w/w component/90% w/w alkylated product (RON alkylated product = 96.4)

[0058] Regarding the octane rating, it was not possible to measure the RON (research octane number) of the pure products, owing to the high volatility of the cuts, which upsets the analysis. Only the cut from run 1 had its RON estimated at 99.4, showing that the stream has a high octane rating. Assessment of the octane rating of the products was carried out with mixtures of each stream with an alkylated product of high isooctane content (80-85% w/w), in the proportion of 10% w/w of the cut generated with 90% w/w of alkylated product. The RON octane rating of the mixtures compared with the octane ratings of the alkylated base used in the mixture showed that all the cuts had similar performance, with an intensified effect in the mixture.

[0059] Regarding the stability of the products, all the cuts showed values of actual and potential gum compatible with values observed for automotive gasolines. Regarding the induction period (IP), despite the low values of IP of the cuts, the results obtained in mixtures with a more stable stream (alkylated product) were much higher, indicating that they are not a problem.

[0060] Another point that deserves special mention is that the sulphur content and nitrogen content in the product derived from fusel oil is compatible for various segments of gasoline, including products that require low contents of impurities. The presence of these contaminants was not assessed in the cuts derived from 99% fossil IAA, since the raw material used in the tests was not the renewable raw material of interest.

Example 2Production of a Bioisoamylene Stream on a Semi-Industrial Scale

[0061] Production of the isoamylene stream on a semi-industrial scale was carried out in a prototype FCC unit, equipped with an 18 m riser, adiabatic regenerator and adiabatic stripper. Table IV presents the operating conditions for obtaining the product. To supply the energy required for dehydration of IAA, torch oil was burned in the regenerator of the unit, maintaining the temperature of the regenerator at the specified value. The catalyst inventory of the prototype unit was 350 kg. Before the production tests, a stream of practically sulphur-free S10 diesel was processed, to purge the systems of condensation and guarantee sulphur content below 10 mg/kg for the stream. The IAA processed in the semi-industrial FCC unit was purified from fusel oil residue from distillation of sugar-cane ethanol (referred to as bio-IAA). The catalyst (Ecat 2), similar to the catalyst used in example 1, was supplied by a Petrobras refinery. The dehydration product was collected and separated from the water produced in a pressure vessel at 1 kgf/cm.sup.2, with the aid of a density sensor, which made it possible to monitor the water-naphtha interface during emptying of the vessel. The liquid product generated in the FCC unit was then fractionated in a distillation unit to generate the final stream. As it was a product derived from raw material of vegetable origin, the product became known as bioisoamylene.

TABLE-US-00004 TABLE IV Operating conditions for production of the bioisoamylene stream (run 1), derived from the dehydration of bio- IAA 99%, obtained on a semi-industrial scale. Parameters Run 1 Feed Bio-IAA 99% (PETROM) Catalyst Ecat 2 TRX, C. 450 T. regenerator, C. 680 T. feed, C. 25 Feed flow rate, kg/h 170 CTO 7.4 Conversion of IAA, % 100 w/w Yields, % w/w: Isoamylenes 52.5 Unreacted alcohol 0.0 Naphtha 68.6 Aromatics 0.0 Water 23.6 Gas 6.7 Coke 1.1

[0062] Table V shows the data from characterization of the distillation cut generated after processing the bio-IAA 99%.

[0063] The product had characteristics similar to those of the products obtained in the pilot plant. Regarding volatility, bioisoamylene was found to be somewhat lighter than the product generated in the pilot plant, with higher RVP, resulting from the greater recovery of light components (compounds with 4 carbons) relative to the products from the pilot plant.

[0064] The final product had high calorific value and octane rating (RON>100 and LCV=44.8 MJ/kg), compatible with the values observed in the cuts produced in the pilot plant. Both properties are excellent, indicating that bioisoamylene is a suitable stream for use in special gasoline formulations.

TABLE-US-00005 TABLE V Data for characterization of the isoamylene stream (run 1), derived from the product of dehydration of bio-IAA 99% on a semi-industrial scale. Tests Results Vapour pressure @ 37.8 C. 130.3 (D5191), kPa Density @ 20 C. (D4052) 0.6573 Distillation (D86) IBP, C. 23.4 T5%, C. 29.0 T10%, C. 30.0 T50%, C. 33.4 T90%, C. 35.4 T95%, C. 35.8 FBP, C. 39.2 Induction period (D525), min 87 (>1.440.sup.i) Actual gum (D381) Not washed, mg/100 mL <0.5 Washed, mg/100 mL <0.5 Potential gum (D873) Not washed, mg/100 mL 12.5 Washed, mg/100 mL 11.5 HCV (D4809), MJ/kg 47.952 LCV (D4809), MJ/kg 44.833 GC (N2377) Saturates, % w/w 14.9 Olefins, % w/w 85.1 Aromatics, % w/w 0.0 Oxygenates, % w/w 0.0 Isoamylenes content, % w/w 63.5 Benzene, % w/w 0.0 H, % w/w (N 2377).sup.ii 14.7 C, % w/w (N 2377).sup.ii 85.3 O, % w/w (N 2377).sup.ii 0.0 Total sulphur (D7039), mg/kg 8.5 Total nitrogen (D5762), mg/kg 0.8 RON ND.sup.iii (100.9.sup.iv) .sup.iValue of IP for mixture of 10% w/w component/90% w/w alkylated product (IP alkylated product > 1.200 min) .sup.iiCalculated from data on composition by GC .sup.iiiNot determined. Sample very volatile, irregular combustion .sup.ivRON value for mixture of 10% w/w component/90% w/w alkylated product (RON alkylated product = 98.5)

[0065] Regarding stability, the product had behaviour similar to that of the products of the pilot plant, and it was not necessary to use an antioxidant additive. Furthermore, it should be emphasized that the product was easier to produce, as post-treatment unit operations were not required to ensure stability.

[0066] Regarding the content of impurities (total N, total S and oxygen), very low values were observed, which did not cause any problem for meeting any current specification for all series of gasolines, including those with low sulphur content.

[0067] In general, the composition of the product, the physicochemical data for bioisoamylene (RVP, density, distillation, LCV and octane rating) and the data on stability indicated very good suitability of the product as a component of gasolines, since its use may provide all the properties required for the formulations.

[0068] In addition, some properties of bioisoamylene are significantly better than those observed for the naphthas obtained by petroleum refining, indicating that this hydrocarbon stream, consisting primarily of olefins with 5 carbon atoms, tends to contribute to the development of various special gasolines.

[0069] As may be deduced from the above examples, the process for dehydration of by-products from ethanol production from sugar cane based on FCC of the present disclosure results in a hydrocarbon stream with a high percentage of isoamylenes, high octane rating and energy content. The stability is compatible with the values observed for automotive gasolines and the content of sulphur and nitrogen-containing compounds is compatible for various gasoline segments. Therefore the product is suitable for various applications, such as development of products with better performance (aviation gasoline, premium gasolines, competition gasolines) or as an octane improver for automotive gasolines.

[0070] Numerous variations falling within the scope of protection of the present application are permitted. The present invention is not limited to the configurations/particular embodiments described above.