Search

CN-116209735-B - Method for producing renewable fuels

CN116209735BCN 116209735 BCN116209735 BCN 116209735BCN-116209735-B

Abstract

The present application describes a process for producing hydrocarbons from an oxygenated hydrocarbon feedstock, such as animal fat, having high nitrogen impurities. The process comprises hydrotreating of an oxygen-containing feedstock in a first hydrotreating bed arranged downstream of the polishing bed. After the first hydroprocessing bed, the gas phase is removed and the liquid hydroprocessing phase is fed with fresh hydrogen to a purification bed disposed upstream of the first hydroprocessing bed that further reduces any nitrogen impurities contained in the purified hydrocarbon product. The particular process arrangement effectively removes nitrogen impurities from the resulting hydrocarbon product resulting in an improved cloud point after isomerization and at the same time the particular arrangement enables fresh hydrogen to be effectively used for refining to provide a refined hydrocarbon product enriched in dissolved hydrogen, wherein a portion of the product may be used as a hydrocarbon diluent in a downstream hydroprocessing bed and/or may be withdrawn between the refining bed and the hydroprocessing bed and isomerized in an isomerization reactor.

Inventors

  • Ville Santio
  • Oli visuri
  • Peterry Lindquist

Assignees

  • 耐思特公司

Dates

Publication Date
20260512
Application Date
20210929
Priority Date
20200930

Claims (20)

  1. 1. A process for producing hydrocarbons from an oxygenated hydrocarbon feedstock having nitrogen impurities of 10 wppm or higher on an elemental nitrogen basis, the process comprising: -a hydroprocessing reactor comprising a first catalytic zone arranged above a second catalytic zone, wherein a hydroprocessing inlet stream comprising an oxygenated hydrocarbon feedstock, a hydrogen-rich gas and optionally a product recycle diluent is introduced into the second catalytic zone at an inlet located between the first catalytic zone and the second catalytic zone, where it is mixed with a portion of a first hydroprocessing effluent from the first catalytic zone, wherein the portion of the first hydroprocessing effluent comprises liquid hydrocarbons having dissolved hydrogen, wherein the second catalytic zone is operated at a temperature and pressure that causes at least hydrodeoxygenation and hydrodenitrogenation, to the extent that a second hydroprocessing effluent from the second catalytic zone of the hydroprocessing reactor comprises predominantly hydrocarbons, and wherein the oxygenated hydrocarbon feedstock has been converted to greater than or equal to 95% hydrocarbons; -the second hydrotreated effluent from the second catalytic zone of the hydrotreatment reactor is subjected to a separation stage in which at least a portion of the second hydrotreated effluent is separated into a gaseous fraction and a hydrotreated liquid, wherein the hydrotreated liquid contains greater than or equal to 95 wt% of hydrocarbons and greater than 1 wppm of nitrogen; -introducing at least a portion of the hydrotreatment liquid and hydrogen-rich gas into the first catalytic zone in the hydrotreatment reactor at an inlet temperature and pressure that cause hydrodeoxygenation and hydrodenitrogenation, the inlet temperature being higher than the inlet temperature in the second catalytic zone of the hydrotreatment reactor; -withdrawing a product side stream containing a portion of the first hydrotreated effluent from the first catalytic zone between the first catalytic zone and the second catalytic zone, the product side stream containing a liquid component and a gaseous component, and wherein the liquid component of the product side stream contains greater than or equal to 99wt% hydrocarbons and less than or equal to 1 wppm nitrogen as elemental nitrogen; -optionally isomerizing the product side stream in an isomerization reactor comprising at least one catalytic zone, wherein the product side stream and a hydrogen-rich gas are introduced into the catalytic zone at an inlet temperature and pressure that causes at least hydroisomerization to produce an isomerized effluent, the hydrogen-rich gas containing less than or equal to 1 ppm nitrogen as elemental nitrogen; Subjecting the isomerisation effluent from the isomerisation reactor to a separation stage, wherein the isomerisation effluent is separated into a gaseous fraction and an isomerisation liquid, wherein the isomerisation liquid contains greater than or equal to 30 wt% branched hydrocarbons and/or an increase in branched hydrocarbons compared to the product side stream is greater than or equal to 30 wt%, Wherein a portion of the first hydrotreated effluent from the first catalytic zone heats the hydrotreated inlet stream, and Wherein the inlet temperature and pressure of the second catalytic zone are from 200 to 400 ℃ and from 10 to 150 bar, and Wherein the inlet temperature and pressure of the first catalytic zone is 250-450 ℃ and 10-150 bar.
  2. 2. The process of claim 1, wherein the liquid component of the product side stream contains greater than or equal to 99wt% hydrocarbons and less than or equal to 0.4 wppm nitrogen as elemental nitrogen.
  3. 3. The process of claim 1, wherein the product side stream is subjected to a stripping stage wherein the product side stream is stripped with a stripping gas H 2 , resulting in a stripped side stream having less than or equal to 0.4 wppm nitrogen as elemental nitrogen and a lower nitrogen content than the product side stream; -isomerizing the stripped side stream in an isomerization reactor comprising at least one catalytic zone, wherein the stripped side stream and a hydrogen-rich gas having nitrogen less than or equal to 1 ppm in elemental nitrogen are introduced into the catalytic zone at a temperature and pressure that causes at least hydroisomerization to produce an isomerized effluent; -subjecting the isomerisation effluent from the isomerisation reactor to a separation stage, wherein the isomerisation effluent is separated into a gaseous fraction and an isomerisation liquid, wherein the isomerisation liquid contains greater than or equal to 30 wt% branched hydrocarbons.
  4. 4. A process according to claim 3 wherein the product side stream is stripped with a stripping gas H 2 resulting in the stripping side stream having less than or equal to 0.3 wppm nitrogen as elemental nitrogen.
  5. 5. The method of any one of claims 1-4, wherein the isomerized liquid is separated into at least aviation fuel having a freeze point of-40 ℃ or less.
  6. 6. The method of any one of claims 1-4, wherein the isomerized liquid is separated into at least aviation fuel having a freeze point of-47 ℃ or less.
  7. 7. The process of any of claims 1-4, wherein cooling is performed during the separation stage of the second hydrotreated effluent to an extent that the hydrotreated liquid has a temperature that is lower than an inlet temperature of the first catalytic zone of the hydrotreatment reactor.
  8. 8. The process of any of claims 1-4, wherein a hydrocarbon diluent and fresh oxygenated hydrocarbon feedstock are not introduced into the first catalytic zone of the hydroprocessing reactor.
  9. 9. The process of any of claims 1-4, wherein the degree of hydrodeoxygenation and hydrodenitrogenation in the second catalytic zone is controlled by the temperature rise between the inlet of the first catalytic zone and the outlet of the first catalytic zone in the first catalytic zone being no more than 10 ℃.
  10. 10. The process of any of claims 1-4, wherein the second catalytic zone in the hydroprocessing reactor has a lower hydrodeoxygenation activity than the first catalytic zone in the hydroprocessing reactor.
  11. 11. The process of any one of claims 1-4, wherein the hydrogen-rich gas used in the first catalytic zone contains less than or equal to 5 wppm nitrogen impurities as elemental nitrogen.
  12. 12. The process of any one of claims 1-4, wherein the inlet temperature and pressure of the second catalytic zone is 250-380 ℃ and 20-120 bar.
  13. 13. The process of any one of claims 1-4, wherein the inlet temperature and pressure of the second catalytic zone is 280-360 ℃ and 30-100 bar.
  14. 14. The process of any of claims 1-4, wherein the second catalytic zone of the hydroprocessing reactor comprises one or more catalysts selected from the group consisting of supported hydrogenation metals.
  15. 15. The method of claim 14, wherein the metal is selected from Pd, pt, ni, co, mo, ru, rh, W or any combination of these.
  16. 16. The method of claim 14, wherein the second catalytic zone comprises one or more catalysts selected from CoMo, niMo, niW, coNiMo supported on a carrier.
  17. 17. The method of claim 16, wherein the support is alumina.
  18. 18. The process of claim 1-4 wherein the hydroprocessing reactor is operated at a WHSV in the range of 0.5-3H -1 and a H 2 flow rate of 350-900 Nl H 2 /l feed.
  19. 19. The process of any one of claims 1-4, wherein the inlet temperature and pressure of the first catalytic zone is 300-430 ℃ and 20-120 bar.
  20. 20. The process of any one of claims 1-4, wherein the inlet temperature and pressure of the first catalytic zone is 330-410 ℃ and 30-100 bar.

Description

Method for producing renewable fuels Technical Field The present invention relates to a process for producing hydrocarbons from an oxygenated hydrocarbon feedstock having nitrogen impurities, and in particular to the efficient use of hydrogen in such processes. Background Conversion of fossil oils (e.g., crude oil) and renewable oils (e.g., vegetable oils or animal fats) into valuable products such as transportation fuels (e.g., gasoline, aviation fuels, and diesel) requires a hydrotreating process, which consumes hydrogen. Refining heavy crude oils and low quality vegetable oils and animal fats, such as animal waste, fats, has increased the need for hydrogen in hydroprocessing processes. Thus, the production, recovery and purchase of hydrogen for the hydrotreatment of oil has a significant impact on the cost of refinery operation. Compared to theoretical consumption, the hydrotreatment of fossil and renewable oils is performed with an excess of hydrogen. The hydrogen remaining after the hydrotreatment step can be purified and recycled, along with other fresh hydrogen, to compensate for the hydrogen consumed in the hydrotreatment step, which is known as make-up hydrogen. During hydrotreating, some reactions occur to varying degrees, based on feedstock composition. Hydroprocessing reactions include double bond hydrogenation, hydrodeoxygenation (HDO), hydrodesulfurization (HDS), hydrodenitrogenation (HDN), hydrodearomatization (HDAr), hydrocracking (HC), and hydroisomerization. Hydroisomerization is typically performed over a bifunctional catalyst having both a metallic dehydrogenation function and an acidic function, for example, a platinum or palladium catalyst, as well as a molecular sieve, such as SAPO-11. If it is not desired to reduce the average molecular weight of the feed during hydrotreating, the isomerization selectivity of the catalyst is important, i.e., to suppress hydrocracking, which typically occurs to some extent during hydroisomerization. This includes a balance between metal dehydrogenation and acid functions that is sensitive to elements that can alter this balance. It is speculated that the amine neutralizes the strong acid sites, resulting in low catalyst acidity and activity. Sulfur is known to poison the metal dehydrogenation function of noble metal catalysts. One of the common feed impurities includes nitrogen, a well known constituent of fossil and renewable sources of oil and animal waste fats. It is reported that average nitrogen impurity levels in crude oil are 940w-ppm and levels as high as 7500w-ppm (Manrique et al (1997)Basic Nitrogen Compounds in Crude Oils:Effect on Mineral Dissolution During Acid Stimulation Processes,SPE-37224-MS;https://www.onepetro.org/conference-paper/SPE-37224-MS). animal waste fats may contain 1000ppm nitrogen or even higher nitrogen is also common, treating undesirable impurities in the feedstock, removal of water-soluble nitrogen compounds by degumming is typical, however, in animal fats, most nitrogen compounds are oil soluble and are much more difficult to remove than water soluble nitrogen compounds. US 2011/0094149A1 (grant IFP ENERGIES Nouvelles) describes a process for hydrotreating a feed from a renewable source in two catalytic zones using a molybdenum catalyst, wherein due to the exothermic nature of the hydrotreating reaction, gaseous and liquid effluents from beds with outlet temperatures higher than inlet temperatures are directly used as recycle to heat fresh feed into the catalytic zones. US 2011/0094149A1 exemplifies the invention using high quality palm oil and soybean oil with low nitrogen impurities of 15 and 23ppm respectively, and it mentions that the feed from renewable sources typically contains various impurities, such as typically 1-100ppm, and even up to 1wt% nitrogen impurities. US 2011/0094149A1 reduces the amount of nitrogen in the examples to about 2% of the original amount and does not hydrotreat any impure feed having a nitrogen content outside the general range of 1-100 ppm. Under the operating conditions described in US 2011/0094149A1, comparative example 1 hydrotreats and isomerizes animal fat having a nitrogen content of about 1 wt.%, which shows that it is possible to hydrotreat impure feeds having a nitrogen content outside the general range of 1-100 ppm. However, the nitrogen content after the hydrodeoxygenation stage is about 2-5ppm, and after isomerization, the yield of aviation fuel fraction (aviation fuel cut) with a high pour point of-10 ℃ is only 5% compared to the aviation fuel requirements. Thus, there remains a need for other hydrotreating processes that can effectively hydrotreat oxygenated hydrocarbons having nitrogen impurities outside the general range of 1-100ppm and ensure low nitrogen levels in the hydrotreated product. In addition, there remains a need for a process that can produce high quality aviation fuel fractions with excellent cold flow properties from oxygenated hydrocarbons having nitro