A process for the two-phase deironing of a hydrocarbon feedstock

Abstract

A method for two-phase iron removal of a hydrocarbon feedstock, the hydrocarbon feedstock enters an iron removal reaction zone, and is sequentially reacted with a hydrogenation protective agent and a hydrogenation metal removal agent in the absence of hydrogen atmosphere to obtain a reaction effluent with reduced sulfur content and iron content. The reaction depth is controlled so that the difference in sulfur content in the hydrocarbon feedstock before and after the reaction / the iron content in the hydrocarbon feedstock ≮ 10. The two-phase iron removal method for hydrocarbons provided by the present application can remove most of the iron-containing compounds in the hydrocarbon feedstock at low cost, providing low-impurity-content feedstock for subsequent devices, thereby ensuring long-period operation of the subsequent devices and improving economic efficiency.

Description

Technical Field

[0001] This invention relates to a method for two-phase deironization of hydrocarbon feedstocks, and more specifically, to a fixed-bed two-phase deironization method for hydrocarbon feedstocks. Background Technology

[0002] The iron content of hydrocarbon feedstocks is one of the main factors limiting the operating cycle of hydrotreating or hydrorefining units. Unlike metals such as nickel and vanadium, which mainly deposit in the catalyst channels, iron, after forming ferrous sulfide under hydrotreating conditions, primarily deposits on the outer surface of the catalyst, with relatively little deposited within the catalyst pores. This leads to a rapid decrease in catalyst bed porosity, which in turn causes a rapid increase in reactor pressure drop and ultimately results in premature unit shutdown, causing unnecessary economic losses.

[0003] To address the issue of high iron content in hydrocarbon feedstocks, common methods used in industrial plants to slow down reactor pressure drop include, but are not limited to: (1) increasing the amount of protective agent, but this method reduces the amount of main catalyst. (2) using a removable protective reactor, which short-circuits when the pressure drop reaches the design limit, allowing the feedstock to directly enter the second reactor, but this method will result in the protective reactor being unusable for a portion of the cycle. (3) using a moving bed reactor, but this significantly increases investment. (4) using a switching protective reactor, which involves a complex switching process and increases investment. (5) using low-pressure hydrodeferrochemical pretreatment technology, but this presents technical challenges.

[0004] US6554994B1 uses an upflow reactor as a protective reactor. During normal operation, the catalyst in an upflow reactor undergoes slight expansion, which enhances its metal-carrying capacity. However, when processing high-iron-content feedstocks, although the pressure drop in the first reactor does not increase rapidly, iron can deposit in the downstream fixed-bed reactor over extended periods, leading to a higher pressure drop in that reactor.

[0005] CN1322097C discloses a method for hydrotreating heavy hydrocarbons with a switchable protective reactor. This method involves setting up a switchable protective reactor system before the main reactor to remove heavy metal impurities and easily coking scale from the feedstock, thereby protecting the main catalyst. However, this protective reactor requires switching operation under high temperature and high pressure conditions, posing a significant operational risk.

[0006] CN1335368A discloses a method for hydrotreating heavy residue oil, which uses a single adsorbent filter bed or a combination of an adsorbent filter bed and an adsorbent catalyst bed to remove suspended particles and ferrous sulfide generated from ferric naphthenate in the heavy residue oil. However, in this method, the adsorbent filter bed can only remove suspended particles, and the adsorbent catalyst bed needs to operate under high pressure, high temperature, and a high hydrogen-to-oil ratio. This is essentially equivalent to increasing the amount of protective agent loaded in the main reactor for residue oil hydrotreating, thus reducing the amount of main catalyst loaded.

[0007] CN103059932A discloses a method for hydrotreating high-acid, high-calcium heavy crude oil. In this method, the high-acid, high-calcium heavy crude oil is mixed with hydrogen and then pretreated in a low-pressure hydrotreating system. The reactor in this pretreatment system is only filled with a hydroprotectant. Studies have shown that iron compounds still enter the subsequent processing units, affecting them and failing to fundamentally remove and effectively intercept the iron compounds.

[0008] CN 107794086 A discloses a low-pressure hydrode-ironization system and method for hydrocarbons. Through the optimization of catalyst gradation and process conditions, a good de-ironization effect is achieved. However, this technology still requires a hydrogen system and a separation system, which results in high costs. Summary of the Invention

[0009] The purpose of this invention is to overcome the disadvantage of high cost when processing hydrocarbon feedstocks with high iron content using existing hydrogenation methods, and to provide a two-phase deironization method for hydrocarbon feedstocks.

[0010] The inventors of this invention discovered that the iron in crude oil after electro-desalting is mainly oil-soluble, including ferric petroleum ether, porphyrin iron, and non-porphyrin iron. The proportions of these three types of iron vary depending on the source of the raw material. Under typical hydrotreating conditions, most ferric petroleum ether reacts relatively easily, while the removal of porphyrin iron and non-porphyrin iron is relatively difficult, requiring higher reaction temperatures to achieve higher removal rates. Further research by the inventors revealed that the key to improving the iron removal rate of hydrocarbon feedstocks lies in two aspects: firstly, providing a certain amount of hydrogen sulfide based on the iron content of the hydrocarbon feedstock to promote the iron removal reaction; and secondly, controlling the flow rate within the reactor to facilitate the deposition of the ferrous sulfide generated during the reaction.

[0011] Based on the above research findings, this invention provides a two-phase deferroplating method for hydrocarbon feedstocks. The hydrocarbon feedstocks enter the deferroplating reaction zone and, in the absence of a hydrogen atmosphere, are sequentially reacted with a hydrogenation protective agent and a hydrogenation demetallizing agent to obtain a reaction effluent with reduced sulfur and iron content. The reaction depth is controlled so that the difference in sulfur content in the hydrocarbon feedstock before and after the reaction / the iron content in the hydrocarbon feedstock is ≥10.

[0012] In one embodiment of the present invention, the reaction depth is controlled such that the difference in sulfur content in the hydrocarbon raw materials before and after the reaction / the iron content in the hydrocarbon raw materials is ≥20.

[0013] In this invention, "the difference in sulfur content in hydrocarbon feedstocks before and after the reaction" refers to the difference between the sulfur content (mass fraction) in hydrocarbon feedstocks and the sulfur content (mass fraction) in the reaction effluent.

[0014] In this invention, "the difference in sulfur content in hydrocarbon feedstock before and after the reaction / the iron content in hydrocarbon feedstock" refers to the ratio of the difference between the sulfur content (mass fraction) in hydrocarbon feedstock and the sulfur content (mass fraction) in the reaction effluent to the iron content (mass fraction) in hydrocarbon feedstock.

[0015] This invention utilizes the hydrogen-supplying properties of hydrocarbon feedstocks, controlling the desulfurization reaction by adjusting catalyst gradation and process conditions to provide a certain amount of hydrogen sulfide. This hydrogen sulfide further promotes the iron removal reaction, simplifying the process of existing technologies and creatively eliminating the need for hydrogen. Furthermore, omitting the gaseous hydrogen stream reduces the flow rate within the reactor, which is beneficial for the deposition of ferrous sulfide, further improving the apparent iron removal rate. In this invention, after the hydrocarbon feedstock passes through the iron removal reaction zone, the iron content in the resulting effluent is significantly reduced, allowing it to be directly fed into any downstream hydrogenation unit.

[0016] In one embodiment of the present invention, the hydrogenation protective agent is a combination of 1-4 hydrogenation protective agents, with the particle size of each hydrogenation protective agent gradually decreasing along the flow direction. More preferably, the hydrogenation demetallizing agent is a combination of 1-4 hydrogenation demetallizing agents, with the particle size of each hydrogenation demetallizing agent gradually decreasing along the flow direction.

[0017] In one embodiment of the present invention, at least one fixed-bed reactor is provided in the iron removal reaction zone. At least one hydrogenation protective agent and at least one hydrogenation demetallizing agent are sequentially graded along the flow direction in the fixed-bed reactor. The hydrogenation protective agent is a combination of 2-4 hydrogenation protective agents, and the particle size of each hydrogenation protective agent gradually decreases along the flow direction. The hydrogenation demetallizing agent is a combination of 2-4 hydrogenation demetallizing agents, and the particle size of each hydrogenation demetallizing agent gradually decreases along the flow direction. The particle size of the hydrogenation demetallizing agent filled at the end of the flow direction is not greater than 1.3 mm.

[0018] Preferably, the particle size of the hydrogenated demetallizing agent loaded at the end of the logistics direction is not greater than 1.1 mm.

[0019] The particle size mentioned in this invention refers to the maximum distance between any two points on the cross-section of the catalyst.

[0020] In this invention, based on the overall catalyst in the iron removal reaction zone, the volume fraction of the hydrogenation protective agent is 20% to 95%, and the volume fraction of the hydrogenation demetallizing agent is 5% to 80%.

[0021] The gradation scheme of the hydrogenation protective agent and the hydrogenation demetallizing agent can be optimized according to the pore structure and activity of the catalyst, as well as the properties of the raw materials and operating conditions.

[0022] In one embodiment of the present invention, the hydrogenation protectant contains a support and an active component loaded on the support. The support is selected from one or more of alumina, silicon oxide and titanium oxide, and the active component is selected from Group VIB metals and / or Group VIII metals. Based on the weight of the hydrogenation protectant, the active component is 0.1% to 15% in terms of oxides.

[0023] In one embodiment of the present invention, the hydrogenation protective agent has a particle size of 0.5–50.0 mm and a bulk density of 0.3–1.2 g / cm³. 3 Specific surface area is 50–300 m² 2 / g.

[0024] In one embodiment of the present invention, the hydrodemetallizing agent contains a carrier and an active component loaded on the carrier. The carrier is selected from one or more of alumina, silicon oxide and titanium oxide, and the active component is selected from Group VIB metals and / or Group VIII metals. Based on the weight of the hydrodemetallizing agent, the active component is 3% to 30% in terms of oxides.

[0025] In one embodiment of the present invention, the particle size of the hydrogenation demetallizing agent is 0.2–2.0 mm, and the bulk density is 0.3–0.8 g / cm³. 3 Specific surface area is 100-250 m² 2 / g.

[0026] In this invention, the number of fixed-bed reactors in the iron removal reaction zone is not particularly limited, but preferably one fixed-bed reactor is set up.

[0027] The fixed-bed reactor in the iron removal reaction zone can be either a downflow reactor or an upflow reactor. A downflow reactor is one in which the material flows from top to bottom; an upflow reactor is one in which the material flows from bottom to top.

[0028] In this invention, the iron content of the hydrocarbon raw material is higher than 5 μg / g, preferably higher than 10 μg / g.

[0029] In one embodiment of the present invention, the sulfur content of the hydrocarbon feedstock is ≥0.1% by weight.

[0030] The hydrocarbon feedstock is any iron-containing oil, such as one or more of naphtha, diesel, wax oil, atmospheric residue, vacuum residue, deasphalted oil, coal tar, and coal liquefaction heavy oil.

[0031] The reaction conditions in the iron removal reaction zone can be conventional conditions in the art, with a reaction temperature of 100–400°C and a liquid hourly space velocity of 0.10–10.0 h⁻¹. -1 Preferably, the reaction temperature in the iron removal reaction zone is 200–370°C, and the liquid hourly space velocity is 0.6–6.0 h⁻¹. -1 .

[0032] The effluent from the iron removal reaction zone is sent to downstream units, such as a hydrogenation unit. It is typically mixed with hydrogen gas before entering a subsequent reactor for further reaction. This subsequent reactor can employ conventional catalyst gradation methods and conventional hydrogenation process conditions, depending on the properties of the hydrocarbon feedstock and the product requirements. The liquid stream can also be sent to other units, such as a catalytic cracking unit.

[0033] The method for two-phase iron removal from hydrocarbon feedstock provided by this invention can remove most of the iron-containing compounds from the hydrocarbon feedstock, providing a feedstock with low iron content for subsequent equipment, ensuring long-term operation of subsequent equipment, thereby increasing the operating efficiency of subsequent equipment and improving economic efficiency.

[0034] Compared with existing technologies, the method provided by this invention cleverly utilizes the hydrogen-supplying properties of hydrocarbon feedstocks. By controlling the reaction depth, the hydrogen sulfide obtained from the hydrocarbon desulfurization reaction is supplied to the iron removal reaction. This eliminates the need for a hydrogen system and a post-separation system, significantly reducing equipment investment and operating costs. Furthermore, omitting hydrogen reduces the material flow rate within the fixed-bed reactor, which is more conducive to the deposition of ferrous sulfide, further improving the apparent iron removal rate. Detailed Implementation

[0035] The method of the present invention will be further described below with reference to specific embodiments, but this does not limit the present invention.

[0036] The catalysts used in the examples and comparative examples were all developed by the Research Institute of Petroleum Processing of Sinopec and produced by the Catalyst Changling Branch. The catalyst gradations used in each example and comparative example are shown in Table 1. Among them, the RG series is the hydroprotectant and the RDM series is the demetallizer. The suffix of the catalyst name indicates the particle size of the catalyst. For example, RG-30B-3.0 means that the grade of the hydroprotectant is RG-30B and its particle size is 3.0 mm. RDM-33-1.3 means that the grade of the hydrodemetallizer is RDM-33 and its particle size is 1.3 mm.

[0037] The raw materials used in all embodiments and comparative examples are the same, and their properties are shown in Table 3.

[0038] Examples 1-4

[0039] A single upflow fixed-bed reactor is set up in the iron removal reaction zone. The reactor is loaded with a hydrogenation protectant and a hydrogenation demetallizing agent sequentially from bottom to top. The catalyst loading ratio is shown in Table 1. Hydrocarbon feedstock enters from the bottom of the fixed-bed reactor and reacts sequentially with the hydrogenation protectant and the hydrogenation demetallizing agent. The reaction effluent is extracted from the top of the fixed-bed reactor. The reaction conditions are shown in Table 2, and the properties of the feedstock and the reaction effluent are shown in Table 3.

[0040] As can be seen from the data in Table 3, by controlling the reaction depth so that the difference in sulfur content in the hydrocarbon raw materials before and after the reaction / the iron content in the hydrocarbon raw materials is not less than 10, the present invention removes most of the iron from the raw materials and can effectively protect the subsequent processing equipment.

[0041] Comparative Example 1

[0042] A single upflow fixed-bed reactor is set up in the iron removal reaction zone. The reactor is loaded with a hydrogenation protective agent and a hydrogenation demetallizing agent sequentially from bottom to top. The catalyst loading ratio is shown in Table 1. Hydrocarbon feedstock and hydrogen are mixed and enter from the bottom of the fixed-bed reactor, reacting sequentially with the hydrogenation protective agent and the hydrogenation demetallizing agent. The reaction products are extracted from the top of the fixed-bed reactor and separated into liquid and gas phases. The reaction conditions are shown in Table 2, and the properties of the feedstock and liquid-phase products are shown in Table 3.

[0043] The comparison between Comparative Example 1 and Example 4 shows that, under the same catalyst gradation and reaction conditions, although Comparative Example 1 is a hydrogen-induced reaction and removes a higher sulfur content, the increased flow rate of hydrogen in the reactor is not conducive to the deposition of ferrous sulfide. Therefore, the iron content of its liquid phase product is actually higher than that of the reaction effluent of Example 4.

[0044] Comparative Example 2

[0045] The reactor setup, material flow setup, and catalyst gradation and loading were the same as in Example 4. The reaction conditions are shown in Table 2, and the properties of the raw materials and the reaction effluent are shown in Table 3.

[0046] The comparison between Comparative Example 2 and Example 4 shows that, under the same conditions of reactor setup, material flow setup and catalyst gradation and loading as in Example 4, the difference in sulfur content in hydrocarbon feedstock before and after reaction / iron content in hydrocarbon feedstock in Comparative Example 2 is 5.5, and the iron content of the oil produced is significantly higher than that of the reaction effluent in Example 4.

[0047] Therefore, compared with the prior art, the present invention ingeniously uses hydrocarbon raw materials as hydrogen source. By optimizing catalyst gradation and process conditions, the hydrogen sulfide obtained from the hydrocarbon desulfurization reaction is used to provide hydrogen for the iron removal reaction, eliminating the need for hydrogen, hydrogen system, and separation system, thereby obtaining reaction effluent with low impurity content at low cost.

[0048] Table 1 Catalyst Gradation and Packing

[0049]

[0050]

[0051] Table 2 Reaction conditions

[0052]

[0053] Table 3 Properties of raw materials and reaction effluents

[0054]

Claims

1. A method for two-phase iron removal from hydrocarbon feedstock, wherein the hydrocarbon feedstock enters an iron removal reaction zone and, in the absence of a hydrogen atmosphere, sequentially reacts with a hydrogenation protective agent and a hydrogenation demetallizing agent to obtain a reaction effluent with reduced sulfur and iron content. The reaction depth is controlled such that the difference in sulfur content in the hydrocarbon feedstock before and after the reaction / the iron content in the hydrocarbon feedstock is ≥10. The hydrogenation protectant comprises a support and an active component loaded on the support. The support is selected from one or more of alumina, silicon dioxide, and titanium dioxide. The active component is selected from Group VIB metals and / or Group VIII metals. Based on the weight of the hydrogenation protectant and calculated as oxides, the active component accounts for 0.1% to 15%. The aforementioned hydrodemetallizing agent contains a support and an active component loaded on the support. The support is selected from one or more of alumina, silicon dioxide, and titanium dioxide. The active component is selected from Group VIB metals and / or Group VIII metals. Based on the weight of the hydrodemetallizing agent and calculated as oxides, the active component accounts for 3% to 30%. Based on the overall catalyst in the iron removal reaction zone, the volume fraction of the hydrogenation protective agent is 20%–95%, and the volume fraction of the hydrogenation demetallizing agent is 5%–80%. The reaction temperature in the iron removal reaction zone is 200~400℃, and the liquid hourly space velocity is 0.10~10.0 h⁻¹. -1 , The hydrocarbon raw material has an iron content higher than 5 μg / g and a sulfur content of not less than 0.1 wt%.

2. The method according to claim 1, characterized in that, Control the reaction depth so that the difference in sulfur content in the hydrocarbon feedstock before and after the reaction / the iron content in the hydrocarbon feedstock is ≥20.

3. The method according to claim 1, characterized in that, The hydrogenation protectant is a combination of 1-4 hydrogenation protectants, with the particle size of each hydrogenation protectant gradually decreasing along the flow direction.

4. The method according to claim 1, characterized in that, The hydrogenation demetallizing agent is a combination of 1-4 hydrogenation demetallizing agents, with the particle size of each hydrogenation demetallizing agent gradually decreasing along the flow direction.

5. The method according to claim 1, characterized in that, The hydrogenation protectant has a particle size of 0.5~50.0 mm and a bulk density of 0.3~1.2 g / cm³. 3 Specific surface area is 50~300m² 2 / g.

6. The method according to claim 1, characterized in that, The particle size of the hydrodemetallizing agent is 0.2~2.0 mm, and the bulk density is 0.3~0.8 g / cm³. 3 Specific surface area is 100~250m² 2 / g.

7. The method according to claim 1, characterized in that, The hydrocarbon feedstock is selected from one or more of naphtha, diesel oil, wax oil, atmospheric residue, vacuum residue, deasphalted oil, coal tar, and coal liquefaction heavy oil.

8. The method according to claim 1, characterized in that, The reaction temperature in the iron removal reaction zone is 200~370℃, and the liquid hourly space velocity is 0.6~6.0 h⁻¹. -1 .

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