FI100248B - Manufacture of middle distillate - Google Patents

Description

100248

MANUFACTURE OF MEDIUM DISTILLATE

ENGINEERING

5

The invention relates to the chemical industry and relates to the production of middle distillate from vegetable oil. The product can be used, for example, as diesel fuel.

10 TECHNICAL BACKGROUND

Vegetable oils are a viable option when it comes to replacing fossil energy with a renewable raw material.

15 The transesterification of vegetable oils (eg rapeseed oil) into diesel fuel is a known technique. Esters are required to have a specific specification for fuel use.

According to U.S. Patent 4,992,605, fatty acids or fatty acid triglycerides can be hydrogenated with conventional desulfurization catalysts (CoMo / alumina or NiMo / alumina) and a diesel fuel with good flammability properties is obtained as the product. The fatty acid feedstock may be a tall oil TOFA fraction (TOFA = Tall Oil Fatty Acid). Triglycerides may be exemplified by the patent. ·. from the following plants: rape, sunflower or palm. By hydrogenating V! The diesel fraction obtained is mainly straight-chain C17 and C18 paraffins with a known high cetane number but very poor refrigeration properties. Thus, the possible amount of blending of such a product in, for example, diesel fuel remains small • · * ··· '.

• · · ♦ · · • * «• · ♦: There are only a few publications on the isomerization of longer-chain> C10 normal paraffins (n-alkanes). Weitkamp, J., Jacobs, P. A. and Martens J.A. have studied the hydroisomerization of C10 ... C16 n-alkanes using platinum and palladium zeo -; * · *: attached on the surface of Y and HZSM-5 in their article Isomerization and Hydrocracking of. C9 Through C16 n-alkanes are Pt / HZSM-5 Zeolite (Applied Catalysis, 8, 1983).

'; * · These catalysts are very acidic, so as a result of their high cracking activity '· ·' 35 hydrocarbons are broken down into shorter, less valuable products.

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A variety of zeolites and molecular sieves have been proposed for the isomerization of long-chain n-alkanes, to which a Group VIII metal, most commonly platinum, has generally been added as a hydrogenating component, cf. e.g. FI patents 72435, 73367 and 89073.

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GENERAL DESCRIPTION OF THE INVENTION

A process for preparing a middle distillate according to claim 1 has now been invented. Preferred embodiments of the invention are set out in the other claims.

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In the process, the fatty acids or triglycerides of the vegetable oil are first hydrogenated to n-paraffins and the n-paraffins are then converted to branched paraffins.

With the two-step process now invented, vegetable oils can be made into a high-grade 15 middle distillate that becomes a component of diesel fuel without special specifications.

DETAILED DESCRIPTION OF THE INVENTION

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Middle distillate means a hydrocarbon mixture boiling in the range of 150 to 400 ° C.

In the process according to the invention, vegetable oil is used as a starting material. It can be "· for example rapeseed oil, pine oil, sunflower oil, mustard oil, palm oil • V: 25 or soybean oil.

• «• · · • · 1 • · ·: Below is a typical rapeseed oil triglyceride molecule and by hydrogenation syn-: 1; products. Hydrogenation of the triglyceride structure is not required when hydrogenating the TOFA fraction.

; ' · ‘Fatty acid molecules can be directly hydrogenated to n-paraffins, whereupon the acid groups react to form water.

• · · k «ti« · • «·« (<3 100248

H O

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H - CO - C (CH2) nCH3 5 H - C - O - CO (CH2) nCH3 + xH2 -► H - C - O - CO (CH2) nCH3 3CH3 (CH2) nCH3 + yCO2 + zH2O + vCO + C3H6 10 n = 14 ... 18

In the first step, the feed is hydrogenated to n-paraffins as described above. In the second step, the molecular structure of the n-paraffins is isomerized with a suitable catalyst to such that good properties (e.g., high cetane number) are maintained but cold properties are significantly improved. This presupposes that the total carbon number remains high and that methyl branches are formed in the carbon chain, e.g. optimum sites for cetane number. The following is an example of the hydrogenation of a TOFA molecule

20 O

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CH3 (CH2) 4CH = CHCH2CH = CH (CH2) 7C-OH + xH2 - »n-C18H38 + yH2O + zCO2 + vCO2 • · * and isomerization« »• n-Cl8H38 + wH2 -> 1-Cl8H38 + wH2 • * · * «· • ♦. *,% 30 For the hydrogenation step, for example, commercial middle distillate • · · desulfurization catalysts, typically ΝΐΜο / Αΐ2θ3 or CoMo / Al203 catalysts, can be used as catalysts.

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For example, all isomerizing molecular sieves and zeolites can be used as catalysts in the isomerization step. Isomerization catalysts with the lowest possible V · 4:35 cracking, such as Pt / SAPO-11 / Al2O3, Pt / ZSM-22 and -23 / Al2O3, are best suited for this. Elemental group VIII metal can be added to the catalyst.

«I

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In the hydrogenation stage, the conditions are: recommended range LH SV, h'1 approx. 1.5 0.5 ... 5 temperature, ° C approx. 390 330 ... 450 5 pressure, bar approx. 50> 30 hydrogen flow, 1/1 about 900> 150

In the isomerization step, the conditions are: recommended range 10 LHSV, h'1 approx. 1 <10 temperature, ° C approx. 330 200 ... 500 pressure, bar approx. 70 generally at pressure of the catalyst to stabilize the hydrogen flow, 1/1 approx. 1000 usually in hydrogen of the catalyst to stabilize 15 The middle distillate prepared in the above-mentioned manner can be used in various products, e.g. as a cetane booster ("supercomponent") for diesel without specific specifications. Good refrigeration properties allow for winter use and high mixing ratios.

20 The product can be aroma-free, which makes it ideal for applications where solvent vapors are exposed or the product is incinerated indoors. Such applications include e.g. aromatic-free solvents and light petroleum.

'·' · '25 Hydrogenation does not make vegetable oil a diesel fuel with good refrigeration properties. Isomerization alone, on the other hand, is not possible for oxygen-containing olefins. At the same time, the process according to the invention achieves difficult-to-combine diesel product properties. The isomerization can be carried out in such a way that it does not go so far as to detrimentally reduce the cetane number.

30 i \ EXAMPLE 1 <* · v * · · • · t «* ♦

The following is an example of the conversion of vegetable oils to high grade middle distillate starting from the fatty acid fraction of tall oil (TOFA).

35 ,,.,: Input

TOFA was used as a feed, the properties of which are shown in Table 1 below.

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Table 1. Tall Oil Fatty Acid 2 (TOFA 2)

Typical Analysis 5 Acid Number 194

Saponification number 195

Resin acids 1.9%

Unsaponifiable 2.4%

Iodine value (Wijs) 152 10 Color ° G 4 ... 5

Density (20 ° C) 0.91 kg / m3 T he factor nD20 1.471

Fatty acid composition,% (typical) 16: 0 0.4 15 17: 0 ai 0.6 18: 0 1.1 18: 1 (9) 30.2 18: 1 (11) 1.1 18: 2 (5, 9) 1.0 20 18: 2 (9.12) 41.7 19: 1 (9) ai 0.6 18: 3 (5,9,12) 9.0 19: 2 (5.9) ai 0 , 3. '! ! 19: 2 (9.12) ai 0.3 25 18: 3 (9.12.12) 0.6 20: 0 0.4 * ··· / 18: 2 conjugate. 5.5 18: 3 conjugate. 2.1: 20: 2 (11.14) 0.2 30 20: 3 (5.11.14) 1.1 20: 3 (7.11.14) 0.2

Other 3.6 100.0 35 6 100248

Hydrogenation TOFA was hydrogenated with a standard middle distillate desulfurization catalyst, N1M0 / Al2O3. An aqueous phase of about 10% by weight was separated from the product with a separatory funnel.

5 Liquid hydrocarbon analyzes are shown in Table 2.

Table 2. Analyzes of hydrogenated TOFA product

Analysis Method Hydrogenated

__ASTM TOFA

Density 50 ° C kg / m3 D4052 771.6

Sulfur mg / kg D4294 0

Br index - D2710 64

Melting point ° C D2500 25

Distillation TA / ° C D86 285 5 ml / ° C 298 10 ml / ° C 301 30 ml / ° C 304 50 ml / ° C 304 70 ml / ° C 306 90 ml / ° C 312 95 ml / ° C 341; TL / ° C 347: Water mg / kg D1744 9.3

Acid numberTAN mgKOH / g D974 0.05 *! .. * Cetane number - D643> 74 * ··· 'n-Paraffins p-% GC-MS 82.0 * ··· * i-Paraffins p-% GC-MS 0 , 6 ·· «- - il - - 1 I - - - • ·« • · * 10 A low acid number indicates that the acid groups are well hydrogenated. The cloud point of the product • *, • ’· · is very high and therefore the product cannot be used as a diesel component: T: except in low concentrations.

Isomerization 15 ': ZSM-22 zeolite was prepared at Abo Academy. Indian National Chemical Laboratory- •: ·; tory (NCL) prepared SAPO-11 molecular sieves according to U.S. Pat. Nos. 4,440,871 and 5,158,700,248,665. Ferreriite was also prepared at NCL. Alumina was added to the zeolites and molecular sieves as a support and platinum as the hydrogenating component.

The catalysts were prepared using standard catalyst preparation processes. Methods of preparation 5 are also described in the above-mentioned FI patents.

The finished catalyst was ground and screened to the appropriate particle size for testing. The catalysts were charged to a tubular reactor and reduced under normal pressure in a stream of hydrogen at 350-450 ° C for one hour. The catalyst was cooled to 150 ° C before pressurization and the start of the hydrogenated TOFA feed. The experimental conditions were: temperature 250 ... 400 ° C, hydrogen pressure 50 bar, feed rate WHSV = 3 1 / h and hydrogen flow H2 / HC = 5001/1. The results are shown in Table 3.

Table 3. Product distribution of hydrogenated and isomerized TOFA by different catalysts 15

Pt / ZSM-22 Pt / SAPO-11 Pt / Ferrierite Gases (<C5), p-% 13 0 1 0 10

Petrol (C5 <174 ° C), p-% 7 17 3 7 3 30

For middle distillate (> 174 ° C), p-% 92 80 97 92 97 60 20 (n-C17 + n-C18) -conv., P-% 39 90 38 79 8 68

Isomerization selectivity of the middle distillate fraction, p-% 65 63 78 75 40 18. ·. : (n-C 17 + n-C 18) conversion as a percentage by mass is calculated from the equation: 25 *. „· I f \ f \ a i f product: n - C17 + n - C, ^ *” ^ input: n-C] 7 + n-C, 8) • · · • · «* · · • ·

The isomerization selectivity of the middle distillate fraction as a percentage by weight is calculated from the equation: • · i «. .

· '* ....., ΛΛ Ύ middle distillate isomers in the product - middle distillate isomers in feed i 30 Selectivity = 100 * ---: ---

V conversion J

. ·, Table 3 shows that the isomerization selectivity is not so much dependent on the • conversion but on the type of catalyst. More acidic zeolites such as ZSM-22 and 1 ferrierite crack more, so their selectivities are inferior.

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However, all of the above, very different types of catalysts are isomerized to hydrogenated TOFA.

Hydrogenated and isomerized TOFA

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The properties of hydrogenated and isomerized TOFA are shown in Table 4.

Table 4. Properties of hydrogenated isomerized TOFA Analysis Method Hydrogenated Hydrogenated and isomerized

__ASTM TOFA TOFA

Density 50 ° C kg / m3 D4052 771.6 769.7

Sulfur mg / kg D4294 0 0

Br index - D2710 64 200

Cloud point ° C D2500 25 -12 Freezing point ° C D97 -12

Filterability ° C EN116 -11

Distillation TA / ° C D86 285 122 5 ml / ° C 298 268 10 ml / ° C 301 280: 30 ml / ° C 304 295 50 ml / ° C 304 297 70 ml / ° C 306 299 [··.] 90 ml / ° C 312 304 / ;: 1 95 ml / ° C 341 314 TL / ° C 347 342 * · 1 1 Cetane number - D643> 74> 74 n-Paraffins p-% GC-MS 82.0 13: 1 ·· i-Paraffins_p -% __ GC-MS__0 ^ __ 73 O1: 10: The properties of hydrogenated and isomerized TOFA are excellent. By isomerization. ··· 'has been able to significantly improve the refrigeration properties by lowering the cetane number. The product is well suited as a diesel component without blending restrictions. It is also well suited for solvents.

15 9 100248 The highest use volumes of the vegetable oil-based middle distillate thus prepared would naturally be as a biocomponent of diesel fuel.

EXAMPLE 2 5

The catalysts were prepared from an SAPO-11 molecular sieve synthesized in the laboratory of NCL in India. SAPO-11 A was crystallized according to U.S. Patent 4,440,871 and SAPO-11 B according to U.S. Patent 5,158,665. 35% Al 2 O 3 was added as support and platinum (about 0.5 wt%) was added by impregnating Pt (NH 3) 4 Cl 2 from an aqueous solution.

Table 5. Catalyst analyzes

Catalyst Pt content of the molecular sieve, p-Pt disperse- __SiO 2 / A12Q3% __ sio_ SAPO-11 A 0.35_JX50__50_ SAPO-11 B [o, 0.4 0.47 85 15 The hydrogenated TOFA feed was isomerized with the above catalysts under the following conditions:

Pressure 50 bar WHSV 3-1 H / HC approx. 600 1/1

: 20 Temperature 340, 360, 370 ° C

. ···. The results are shown in Table 6.

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Table 6. Product distribution of hydrogenated and isomerized TOFAr with catalysts SAPO-11 A and B

Feature SAPO-11A SAPO-11A SAPO-11B SAPO-11B SAPO-11B

__340 ° C 360 ° C 340 ° C 360 ° C 370 ° C

Gases 1.0 1.1 <1.0 2.1 5.0 (<nC5), p -% ______

Petrol 1.5 3.9 2.6 9.6 16.0 (nC5 <174 ° C), p -% ______

Middle distillate 97.5 95.0 97.4 88.3 79.0 (> 174 ° C) ______ (n-C17 + n-C18) 20.1 63.4 48.4 93.3 95.7 Conv. , p -% ______

Isomerization selectivity of the middle distillate fraction 76.2 78.9 81.4 73.3 63.9, wt% _____ 5 As can be seen from the results in the table, the isomerization selectivity of the middle distillate fraction decreases significantly if the conversion level is increased by> 90 wt%.

EXAMPLE 3 10 The conversion level can be increased by lowering the feed rate (WHSV). Catalyst: SAPO-11 A was hydrogenated TOFA wasomerized with three different WHSV values: • · ·. ** ·. 1, 2 and 3 h-1. The other conditions were the same as in Example 2. The results are shown. in Table 7.

• »· • · · • *« • · • · # # »• · · 11 100248

Table 7. Effect of WHSV on isomerization of TOFA with SAPO-11 A catalyst

Property 340 ° C / 340 ° C / 340 ° C / 360 ° C / 1360 ° C / I 360 ° C / __1 h-1 2 h-1 3 h-1 1 h-1 2 h-1 3 h-1

Gases 2.1 1.1 1.0 2.3 3.1 1.1 (<nC5), p -% _______

Petrol 2.7 2.1 1.5 8.7 3.9 3.9 (nC5 <174 ° C), p -% _______

For the middle 95.3 96.9 97.5 89.0 93.1 95.0 (> 174 ° C) _______ (n-C17 + n-C18) 54.9 33.1 20.1 92.2 80.3 63.4 conv., P -% _______

Isomerization selectivity of middle distillate fraction 78.3 78.1 76.2 74.3 77.8 78.9, wt% ______

It can be seen from the results in Table 7 that the conversion level can be increased both by raising the temperature 5 and by lowering the value of the WHSV. The selectivity only starts to decrease markedly when the conversion level exceeds the limit of 90% by weight.

«« 1 • «· • · · • · • ·%« · * · · • · · · 1 • · «• ·« • · • · 1 1 «« ♦ · »• 1 · • · ·

Claims (10)

A process for preparing intermediate distillates from plant oil, characterized in that - in a first step, the fatty acids or triglycerides of the plant oil are hydrogenated as n-paraffins and that in a second step the n-paraffins are catalytically converted to branched-chain paraffins. 2. A process according to claim 1, wherein the plant oil is rapeseed oil, tall oil, sunflower oil, mustard oil, palm oil or soybean oil. 10 A process according to claim 1 or 2, in which desulphurisation catalyst for intermediate distillates is used as the catalyst in the first step. The method of claim 3, wherein the catalyst contains NiMo or CoMo. 15 Process according to any of claims 1 to 4, wherein the catalyst in the second stage contains isomerizing molecular sieve or zeolite. The method of claim 5, wherein the catalyst contains SAPO-11, ZSM-22 or ferrierite. 20 A process according to any of claims 1 to 6, wherein a metal of element group VIII is added to the catalyst in the second step. . A method according to any one of claims 1 to 7, wherein the catalyst of the second stage contains platinum. »» * * · · • t A method according to any of claims 1 to 8, wherein the catalytic converter in the second is; the step contains AI2O3 or S1O2. * ♦ »• * · 30 The method of claims 5 and 9, wherein the catalyst of the second stage is: Pt / SAPO-11 / Al2O3, Pt / ZSM-22 / Al2 O3, Pt / ZSM-23 / Al2 O3 or Pt / SAPO-11 / Si02. il »• · · * A · Ψ