Method for reducing fouling in catalytic cracking

Abstract

A method is disclosed for reducing fouling in catalytic cracking. The method includes subjecting a recycled fossil-based feedstock to a heat treatment, evaporating the heat-treated feedstock, hydrotreating resulting evaporation distillate and performing catalytic cracking of the hydrotreated distillate in a presence of a solid acid catalyst.

Claims

1. A method of producing a cracking product, the method comprising: subjecting a recycled fossil-based feedstock containing metallic impurities and reactive components to a heat treatment; evaporating the heat-treated feedstock to produce distillate(s) and a residue fraction containing reacted metallic impurities of the recycled fossil-based feedstock; hydrotreating a fraction of the distillate(s) boiling at or above 100° C. to produce a hydrotreated distillate; and performing catalytic cracking of the hydrotreated distillate as a feed component of a feed in a presence of a solid acid catalyst; wherein a heating temperature during the heat treatment is at least 290° C. and wherein the heat treatment is carried out for at least 1 minute, wherein the heat treatment is carried out at a pressure of 2.0 bar or more, wherein a cracking temperature is 510° C. or more; and wherein the feed of the catalytic cracking comprises: a biomass-based feed component in addition to the hydrotreated distillate.

2. The method according to claim 1, comprising: a pre-treatment of de-watering the recycled fossil-based feedstock.

3. The method according to claim 1, wherein the heat treatment is carried out prior to the evaporating.

4. The method according to claim 1, wherein the heat treatment is carried out as a part of the evaporating.

5. The method according to claim 1, wherein the evaporating is carried out by distillation in at least one of a distillation column or in a fractionation tower.

6. The method according to claim 1, wherein the evaporating is carried out in a fast evaporation apparatus, configured as at least one of a thin film evaporator, a flash evaporator, a short path evaporator, a plate molecular still, or a falling film evaporator.

7. The method according to claim 1, wherein no hydrogen gas is fed in when performing the cracking.

8. The method according to claim 1, wherein the heating temperature during the heat treatment is at least one of at least 300° C., at least 310° C., at least 320° C. or at least 330° C.

9. The method according to claim 1, wherein the heat treatment is carried out for at least one of at least 2 minutes, at least 5 minutes, at least 10 minutes, at least 20 minutes, at least 30 minutes, at least 40 minutes, at least 50 minutes, at least 60 minutes, at least 80 minutes or at least 100 minutes.

10. The method according to claim 1, wherein the heat treatment is carried out at a pressure of 3.0 bar or more.

11. The method according to claim 1, comprising: for producing a fuel or a fuel component from at least a fraction of the cracking product.

12. The method according to claim 1, wherein the feed of the catalytic cracking comprises: a fossil feed component in addition to the hydrotreated distillate and the biomass-based feed component.

13. The method according to claim 12, wherein the heat treatment is carried out prior to the evaporating.

14. The method according to claim 12, wherein the heat treatment is carried out as a part of the evaporating.

15. The method according to claim 14, wherein the evaporating is carried out by distillation in at least one of a distillation column or in a fractionation tower.

16. The method according to claim 1, wherein the heat treatment is carried out continuously prior to the evaporation step in a separate vessel, and/or in addition the heat treatment is carried out at least partly during the evaporation step.

17. The method according to claim 1, wherein the evaporation step is carried out in more than one stage so that at least three fractions are generated in total.

18. The method according to claim 1, wherein the distillate(s) from the evaporation step are subjected to a second evaporation step to provide at least one distillate fraction and at least one further residue fraction.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is an exemplary flow chart of a procedure as disclosed herein;

(2) FIGS. 2 and 3 are exemplary results of implementing a method as disclosed herein.

(3) The procedure of the present invention is schematically shown in FIG. 1. As illustrated in FIG. 1, water (1) may be removed in a de-watering step, insoluble components (2) may be removed e.g. in a centrifugation step, and distillation residue (5) is removed in an evaporation step, e.g. in a thin film evaporator. At least one of the distillate fractions (3 and 4) is then forwarded to hydrotreatment and subsequently to catalytic cracking.

(4) The present invention further relates to a fuel component obtainable by the method of the present invention.

(5) As can be seen from the results of the Examples (and in particular from FIGS. 2 and 3), the method of the present invention enables efficient production of high-value fuel components, especially in the gasoline and middle distillate range.

(6) The fuel is preferably a fuel component comprising a fraction of the cracking product, wherein the fraction is preferably a fraction boiling in the gasoline range, or a fraction boiling in the middle distillate range.

(7) The present invention further relates to a use of a cracking product or of a fraction thereof obtained by the method of the present invention for producing a fuel or a fuel component.

EXAMPLES

(8) The present invention is further illustrated by way of Examples. However, it is to be noted that the invention is not intended to be limited to the exemplary embodiments presented in the Examples.

Example 1

(9) Two waste oil samples obtained from commercial sources were pre-treated according to the procedure that is described herein. The waste oil was de-watered in a rotary evaporator at 80 mbar and 100° C. oil bath temperature.

(10) Water and minor amounts of light residues were distilled off and discarded while the residue after de-watering was fed to a batch reactor for heat treatment. The batch reactor was heated up to 320° C. and this temperature was maintained for 1 hour. During this time, the batch reactor remained closed and the pressure inside the batch reactor increased up to about 13 bar.

(11) The thus heat-treated waste oil was subjected to centrifugation at 4300 rpm and 50° C. for 30 minutes. The solids/sludge and entrained oil obtained from centrifugation were discarded and the supernatant was subjected to a two-stage thin film evaporation (TFE) under reduced pressure.

(12) In the first stage, which was performed at approximately 135° C. and 0.5 mbar pressure, a distillate fraction boiling at or below 360° C. (at normal pressure) was obtained. The residue, i.e. the evaporation bottoms, from the first stage was subjected to another evaporation step at approximately 280° C. and 0.1 mbar. This resulted in a second distillate fraction with an approximate boiling point range of 360-560° C. (at normal pressure), as well as a residue (distillation bottoms). The second distillate fraction was further used as a feedstock in catalytic cracking experiments whereas the residue was discarded.

(13) The catalytic cracking experiments were carried out in a fixed bed reactor which is originally based on the ASTM D3907 standard. The catalytic cracking was carried out in a reactor filled with 30 g zeolite-containing solid acid catalyst (apparent bulk density: 1050 kg/m.sup.3, catalyst particle size: 5-20 mm) and was driven batch-wise using 10 g feed (catalyst-to-oil ratio 3) at 500° C. using a cracking time of 15 min per each 10 g batch. After each batch, the catalyst was regenerated by combustion of formed coke. The amount of CO and CO.sub.2 formed by combustion during the regeneration was used as a measure of the amount of coke formation. Further, the product fraction (liquid product) of the cracking unit was analysed by simulated distillation to determine the boiling point distribution of the hydrocarbons.

(14) The cracking procedure was repeated twice for both waste oil samples, and the average value from the two repetitions was used for evaluation. The results are shown in FIG. 2 (waste oil #1) and FIG. 3 (waste oil #2) and in Table 1. The data series denoted ‘HT-TFE-500° C.’ refers to the results of Example 1.

Example 2

(15) The temperature in the catalytic cracking step was increased to 530° C. Except for this, the procedure of Example 1 was repeated. The data series denoted ‘HT-TFE-530° C.’ refers to the results of Example 2.

Example 3

(16) The temperature in the catalytic cracking step was increased to 550° C. Except for this, the procedure of Example 1 was repeated. The data series denoted ‘HT-TFE-550° C.’ refers to the results of Example 3.

Comparative Example 1

(17) The procedure of Example 1 was repeated, except that the heat treatment step was omitted. That is, the de-watered waste oil was directly subjected to centrifugation without the heat treatment step and evaporation was carried out after centrifugation. The data series denoted ‘TFE-500° C.’ refers to the results of Comparative Example 1.

Comparative Example 2

(18) The temperature in the catalytic cracking step was increased to 530° C. Except for this, the procedure of Comparative Example 1 was used. The data series denoted ‘TFE-530° C.’ refers to the results of Comparative Example 2.

Comparative Example 3

(19) The temperature in the catalytic cracking step was increased to 550° C. Except for this, the procedure of Comparative Example 1 was used. The data series denoted ‘TFE-550° C.’ refers to the results of Comparative Example 3.

(20) TABLE-US-00001 TABLE 1 Coke Unreacted Coke Unreacted yield material yield material Heat Cracking (waste (waste (waste (waste treatment temp. oil #1) oil #1) oil #2) oil #2) Example 1 320° C./1 h 500° C. 6 wt.-% 2 wt.-% 5 wt.-% 2 wt.-% Example 2 320° C./1 h 530° C. 6 wt.-% 2 wt.-% 5 wt.-% 2 wt.-% Example 3 320° C./1 h 550° C. 7 wt.-% 2 wt.-% 6 wt.-% 2 wt.-% Comparative none 500° C. 12 wt.-% 9 wt.-% 19 wt.-% 11 wt.-% Example 1 Comparative none 530° C. 20 wt.-% 11 wt.-%  18 wt.-% 11 wt.-% Example 2 Comparative none 550° C. 26 wt.-% 15 wt.-%  15 wt.-% 11 wt.-% Example 3

(21) As can be seen from the results of FIGS. 2 and 3 and from Table 1, coke formation is significantly reduced when employing a heat treatment step before the evaporation step. In addition, the amount of non-reacted material in the catalytic cracking procedure is reduced when employing the heat treatment step. A further improvement of the catalytic cracking product is achieved by hydrotreating the distillate after evaporation and before catalytic cracking.

(22) Therefore, the combined use of heat-treatment and evaporation allows a significant improvement of cracking efficiency and cracking catalyst life (reduced coking).