Two-stage heavy oil upgrading method and upgrading system

Abstract

This invention discloses a two-stage method and system for upgrading heavy oil in the presence of methane, belonging to the field of heavy oil processing and clean utilization technology. The method includes a pretreatment stage and an upgrading stage: the heavy oil feedstock is introduced into a first reactor and pretreated in a methane or methane / hydrogen mixed atmosphere with a first catalyst to obtain intermediate oil; the intermediate oil is then directly introduced into a second reactor and upgraded in a methane atmosphere with a second catalyst. Oxygen is introduced during the reaction for in-situ heating to promote methane activation and enhance the upgrading effect of heavy oil. This invention, through the functional division of the two-stage reaction and the combination of in-situ heating, reduces the impact of heavy oil metallic impurities and asphaltenes on the upgrading reaction, improves the problem of simultaneous methane activation and catalyst poisoning in single-stage methane-containing systems, facilitates methane participation in oil upgrading, improves the desulfurization, denitrification, demetallization, and viscosity reduction effects of heavy oil, and reduces the amount of external hydrogen used.

Description

Technical Field

[0001] This invention relates to the field of heavy oil processing and clean utilization technology, and more specifically, to a two-stage method and system for upgrading heavy oil to form methane. Background Technology

[0002] With the continuous depletion of global light crude oil resources, the proportion of residue oil with high metal, heteroatom, and asphaltenes content in the feedstock structure of refining enterprises is constantly increasing. This type of residue oil is typically rich in polycyclic aromatic hydrocarbons, gums, asphaltenes, large molecular hydrocarbons, and difficult-to-remove metallic impurities such as Ni and V. It is characterized by high viscosity, high carbon residue, and high instability, making it one of the most difficult feedstocks to efficiently convert in the refining industry. Traditional residue oil upgrading paths mainly rely on deep hydrocracking or thermal processing, which can achieve high desulfurization and denitrification efficiencies, but have significant limitations. With energy structure adjustments and rising hydrogen costs, the industry urgently needs a residue oil upgrading technology route with lower hydrogen consumption, greater economy, and higher efficiency.

[0003] In recent years, research on using methane to replace part of the hydrogen in the upgrading of heavy oil has attracted attention. Methane is widely available, low in cost, and high in hydrogen content, making it a potential hydrogen source substitute. However, existing one-stage methane-based residue upgrading technologies still face a series of technical bottlenecks. Due to the high C–H bond energy of methane (approximately 439 kJ / mol), it is difficult to be effectively activated on the surface of conventional catalysts, resulting in insufficient active hydrogen generation and difficulty in supporting deep desulfurization, denitrification, and macromolecular cracking. At the same time, high-metal, high-colloidal residues easily generate a large amount of carbon deposits on the catalyst surface, leading to the coverage of active sites and short-cycle deactivation of the catalyst. In addition, one-stage methane-based processes struggle to effectively remove metal impurities and asphaltenes from the feed, resulting in poor adaptability of the system to difficult-to-process residues and limited upgrading and liquid recovery capabilities. Existing technologies attempt to alleviate the above problems by improving gas-liquid mass transfer, increasing reaction temperature, or optimizing catalyst composition. However, they do not fundamentally change the reaction mode in which methane activation and catalyst poisoning and deactivation processes are highly coupled in time and space, making it difficult to fundamentally construct the reaction preconditions suitable for the directional activation of methane in complex heavy oil systems.

[0004] Therefore, there is an urgent need in this field for a new technical approach to provide a new methane upgrading route for high-metal, high-colloidal asphalt residue oil that can operate stably for a long time, has low hydrogen consumption, and has good industrial adaptability.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a two-stage method and system for upgrading heavy oil to methane, so as to solve or improve the above-mentioned technical problems.

[0007] This invention is implemented as follows: In a first aspect, the present invention provides a two-stage method for upgrading heavy oil containing methane, the upgrading method comprising the following steps: Heavy oil feedstock is introduced into the first reactor and pretreated in a methane atmosphere or a methane / hydrogen mixed atmosphere to reduce the influence of metal impurities and / or asphaltenes on the catalyst, thereby producing intermediate oil. The intermediate oil is directly introduced into the second reactor, where it undergoes an upgrading reaction in contact with the second catalyst under a methane atmosphere. Oxygen is introduced during the reaction to provide in-situ heating, which maintains the heat required for methane to participate in the heavy oil upgrading reaction in the second reactor and promotes the participation of methane in the heavy oil upgrading reaction.

[0008] In a second aspect, the present invention provides a two-stage heavy oil methane upgrading system for implementing the heavy oil methane upgrading method as described in any of the foregoing embodiments. The upgrading system includes a first reactor, a second reactor, a separation and circulation unit, an oxygen supply system, a feed gas supply system, and an oil collection unit; The oxygen supply system provides oxygen to the quality improvement system and participates in the in-situ heating in the second reactor. The feed gas supply system provides the upgrading system with a methane atmosphere or a methane / hydrogen mixed atmosphere.

[0009] The present invention has the following beneficial effects: This invention provides a two-stage method and system for upgrading heavy oil in the presence of methane. By implementing the heavy oil pretreatment reaction and the methane-involved upgrading reaction in two separate reactors, it achieves a functional division between the poisoning control process and the directed methane activation process. The first reactor is beneficial for preferentially removing or converting metallic impurities, gums, and asphaltenes in the heavy oil, reducing their interference with subsequent upgrading reactions. The second reactor, with in-situ oxygen heating under a methane atmosphere, helps meet the local endothermic requirements during the methane activation process, promoting the participation of methane in the desulfurization, denitrification, demetallization, and viscosity reduction reactions of intermediate oil products. Compared with existing single-stage methane-in-the-containment systems, this invention helps alleviate the contradiction between methane activation and catalyst poisoning, improves the upgrading depth and reaction stability, and achieves better viscosity reduction, desulfurization, denitrification, and demetallization effects while reducing the amount of external hydrogen used, showing good prospects for industrial application. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0011] In a first aspect, the present invention provides a two-stage method for upgrading heavy oil containing methane, the upgrading method comprising the following steps: Heavy oil feedstock is introduced into the first reactor and pretreated in a methane atmosphere or a methane / hydrogen mixed atmosphere to reduce the influence of metal impurities and / or asphaltenes on the catalyst, thereby producing intermediate oil. The intermediate oil is directly introduced into the second reactor, where it is contacted with the second catalyst under a methane atmosphere to carry out an upgrading reaction. Oxygen is introduced during the reaction for in-situ heating to promote the participation of methane in the upgrading reaction of heavy oil.

[0012] It should be noted that, through the synergistic effect of the two-stage reactions in the first and second reactors, this invention facilitates the deep upgrading of heavy oil under conditions of no or low external hydrogenation. The upgrading reaction in the second reactor promotes further cracking of intermediate oil products and the conversion process involving methane. Specifically, the oxygen introduced into the second reactor triggers a mild oxidation reaction of methane on the surface of the second catalyst, providing the heat required for the directional activation of methane and promoting desulfurization, denitrification, demetallization, and viscosity reduction of intermediate oil products. This results in a final product exhibiting a high viscosity reduction rate and good desulfurization, denitrification, and demetallization effects.

[0013] In this method, the intermediate oil produced in the first reactor does not require cooling and is directly introduced into the second reactor for upgrading. Simultaneously, oxygen is introduced for in-situ heating, causing a mild oxidation reaction of methane to generate heat, increasing the methane activation rate and enhancing the overall stability of the system. Through this synergistic mechanism, deep upgrading of residue oil can be achieved under conditions of no or low external hydrogenation, significantly reducing product viscosity and improving product stability. The final products of the upgrading reaction are processed by a separation and recycling unit, separating the light gas from the oil. The light gas (mainly methane and a small amount of cracked gas) can be partially recycled back to the second reactor for reuse, improving resource utilization; the oil is then output as a deeply upgraded product. This method enables continuous and stable industrial operation, with extremely low hydrogen consumption, long catalyst life, and strong adaptability, making it suitable for the current development needs of low-carbon and low-hydrogen-consumption refining.

[0014] This invention employs a pretreatment reaction in the first reactor to achieve poisoning control, and a upgrading reaction with in-situ heating in the second reactor. This is a two-stage, methane-co-modification method with functional division of reactions. This upgrading method exhibits good adaptability to the metal content, asphaltenes content, and reaction atmosphere composition of heavy oils. Stable operation can be achieved by adjusting the reaction conditions in each stage. It is suitable for low-quality residual oil resources with high metal and high asphaltenes content, and has good engineering scale-up potential and industrial application value. Detailed analysis follows: To address the strong endothermic nature and susceptibility to thermal instability in the methane reaction, this invention proposes a restricted in-situ heating strategy in a two-stage reaction system. The pretreatment reaction in the first reactor removes or transforms metallic impurities, gums, and asphaltenes from the residue oil, creating favorable preconditions for methane activation. The upgrading reaction in the second reactor achieves the targeted activation of methane and hydrogen supply in a relatively clean reaction environment. In the upgrading reaction of the second reactor, the restricted in-situ heating strategy does not aim to raise the overall reaction temperature, but rather precisely limits the heating intensity and location, using it only to meet the local endothermic requirements of the targeted methane activation process to maintain its stability. This restricted heating method effectively avoids problems such as complete methane oxidation, excessive oxidation of the oil phase, and localized temperature runaway, achieving synergistic optimization of methane activation, hydrogen source generation, and reaction stability.

[0015] This invention controls the reaction temperature, pressure, and volume hourly space velocity (VHSV) of the pretreatment reaction within a defined window. This ensures that the reaction primarily focuses on the capture of metal impurities, stabilization of asphaltenes, and the conversion of some sulfur- and nitrogen-containing compounds. Methane in this stage mainly serves as the reaction atmosphere or mass transfer medium, without undergoing significant dissociation and activation reactions, thus yielding intermediate oil products with low metal content and low asphaltenes interference. Based on this, continuous and directional activation of methane is achieved in a second reactor under low metal and low asphaltenes interference conditions. This functionally differentiated design effectively alleviates the inherent contradiction of simultaneous methane activation and catalyst poisoning in existing single-stage methane-containing systems, constructing stable reaction preconditions that are difficult to achieve in single-stage systems.

[0016] Because the methane activation stage and the poisoning control stage are effectively separated in time and space, the system of the present invention is beneficial to reducing the carbon deposition rate of the catalyst metal center and inhibiting the activity decay, making the reaction process more stable, and is beneficial to maintaining a stable quality improvement effect over a longer operating period. It is significantly better than the comparative system that has not performed functional division or has not adopted a limited heating strategy.

[0017] The upgrading reaction in the second reactor is carried out under conditions of low metal and low gum interference, causing methane to undergo directional activation and dissociation adsorption on the surface of the second catalyst, becoming the main hydrogen source for the deep desulfurization, denitrification, demetallization, and cracking reactions of intermediate oil products. This stage fully utilizes the active hydrogen generated by the directional activation of methane to achieve efficient removal of sulfur, nitrogen compounds, and metals from the residue oil, as well as directional cracking of macromolecular structures. While significantly reducing the amount of external hydrogen used, it also achieves a simultaneous reduction in viscosity, residual carbon, and gum asphaltenes content, balancing the depth of upgrading with operational economy.

[0018] In an optional embodiment, the amount of oxygen introduced during the upgrading reaction is 0.01 vol%–1 vol% of the amount of methane used. Furthermore, the amount of oxygen introduced is 0.01 vol%–0.1 vol% of the amount of methane used. Furthermore, the amount of oxygen introduced is 0.01 vol%–0.05 vol% of the amount of methane used.

[0019] For example, the amount of oxygen introduced is any one of 0.01 vol%, 0.02 vol%, 0.03 vol%, 0.04 vol%, and 0.05 vol% of the amount of methane used, or other values ​​in the range of 0.01 vol%–0.05 vol%.

[0020] To meet the strong endothermic requirements of the methane reaction and improve the directional activation efficiency of methane, this invention employs in-situ heating in a second reactor. By introducing oxygen into the methane atmosphere used in the second reactor, a controlled, mild methane oxidation reaction occurs on the surface of the second catalyst, generating sufficient heat of reaction to maintain temperature stability and producing additional active hydrogen species and CH4. x This process further promotes the macromolecular cracking, desulfurization, denitrogenation, demetallization, and stabilization of residual oil, while controlling the oxygen content within a safe operating range. Related reactions include mild oxidative heating reactions, incomplete surface oxidation reactions, and hydroxide reactions, which are analyzed in detail below: (1) Mild oxidative heating reaction: CH4 + 0.5O2 → CO + 2H2; (2) Incomplete surface oxidation reaction: CH4 + O* → CH x * + OH*; (3) Hydroxylation reaction: H* + O* → OH*; H* + OH* → H2O.

[0021] It should be noted that the oxygen introduced in the upgrading reaction is only used to trigger a mild oxidation reaction of methane to meet the endothermic requirements of directional activation of methane, and does not trigger a complete oxidation reaction of methane or a deep oxidation reaction in the oil phase.

[0022] In an optional implementation, the method of oxygen introduction is selected from any of the following: Option 1: Introduce the mixture into the second reactor after premixing with methane; Method 2: Introduced through an independent gas path at the inlet of the second reactor; Method 3: Introduced via an independent gas path to the upper part of the second reactor bed.

[0023] In an optional embodiment, when the atmosphere of the pretreatment reaction is a mixture of methane and hydrogen, the volume fraction of hydrogen is 5%–50%.

[0024] Furthermore, the volume fraction of hydrogen is 10%–30%; for example, in a hydrogen / methane mixture, the volume fraction of hydrogen can be selected from any one of 10%, 20%, 25% and 30%, or other values ​​within 10%–30%.

[0025] In an optional implementation, the atmosphere for the pretreatment reaction may also use pure methane, if necessary.

[0026] And / or, the heavy oil feedstock is selected from at least one of oil sands, heavy oil, extra-heavy oil, atmospheric residue, and vacuum residue. In embodiments of the present invention, vacuum residue is used; in other embodiments, the type of heavy oil may be selected reasonably based on actual circumstances.

[0027] It should be noted that the heavy oil feedstock used in the embodiments of the present invention is obtained by pre-treatment of the feedstock oil. The pre-treatment of the feedstock oil in the present invention includes: filtration, heating and homogenization of the feedstock oil to remove mechanical impurities and improve its fluidity, while controlling the water content, so as to obtain heavy oil feedstock that can be directly used for methane upgrading.

[0028] The water content in the heavy oil feedstock is adjusted appropriately according to different types of crude oil, and the lower the water content, the better. Specifically, in this embodiment of the invention, the water content is controlled to be 0–0.2 wt%. If the water content in the heavy oil feedstock is too high, the water will require a large amount of latent heat to vaporize in the heating furnace and tower, resulting in a significant increase in fuel consumption, energy waste, and may also trigger the safety valve to trip or even cause an overpressure accident. If liquid water comes into contact with the high-temperature catalyst bed during the reaction, it will vaporize instantly, producing a steam explosion effect, causing the catalyst particles to thermally break and pulverize, increasing the pressure drop in the bed, and causing permanent deactivation and pulverization of the catalyst.

[0029] When heavy oil feedstock is fed into the first reactor for pretreatment, it comes into contact with the first catalyst and reacts under a methane or methane / hydrogen mixed atmosphere, undergoing demetallization, desulfurization, denitrification, and partial cracking reactions. This stage of the reaction can significantly reduce the metal impurities and gum content in the feedstock, improving oil stability.

[0030] In an optional embodiment, the pretreatment reaction is carried out at a temperature of 340°C–420°C, a pressure of 3 MPa–15 MPa, and a volumetric hourly space velocity of 0.1 h⁻¹. -1 –1.0 h -1 .

[0031] Furthermore, the pretreatment reaction was carried out at a temperature of 360℃–400℃, a pressure of 6 MPa–12 MPa, and a volume hourly space velocity of 0.1 h⁻¹. -1 –0.5 h -1 .

[0032] It should be noted that the pretreatment reaction can significantly reduce the content of metallic impurities such as Ni and V in intermediate oil products, while partially cracking the gum and asphaltenes and achieving the initial removal of sulfur and nitrogen heteroatoms, thereby providing a low-toxicity and highly stable feed for the second catalyst.

[0033] In an optional embodiment, the upgrading reaction is carried out at a temperature of 350°C–450°C, a pressure of 5 MPa–12 MPa, and a volume hourly space velocity of 0.1 h⁻¹. -1 –1.0 h -1 .

[0034] Furthermore, the upgrading reaction was carried out at a temperature of 380℃–420℃, a pressure of 6 MPa–10 MPa, and a volume hourly space velocity of 0.1 h⁻¹. -1 –0.3 h -1 .

[0035] It should be noted that if the upgrading reaction time is too short, the conversion depth of the heavy oil feedstock may be insufficient, resulting in a low yield of light oil; incomplete hydrotreating and deimpurification may lead to poor quality of the final product; and insufficient thermal reaction may exacerbate scaling and coking in the equipment. If the upgrading reaction time is too long, excessive cracking and hydrogenation of the heavy oil feedstock may occur, reducing economic efficiency; the active sites of the catalyst may be excessively covered or sintered; and maintaining the reaction system at high temperatures for extended periods may shorten equipment lifespan and increase energy consumption.

[0036] In an optional implementation, after the upgrading reaction, the viscosity reduction rate of the heavy oil feedstock is ≥95%, the desulfurization rate is ≥60%, the denitrification rate is ≥50%, and the demetallization rate is ≥95%, wherein the removed metals are selected from at least one of nickel, vanadium, calcium, sodium, iron, and magnesium. It should be noted that the types of metals removed during the methane upgrading of heavy oil are numerous, and specific testing should be conducted according to actual needs.

[0037] Furthermore, after the upgrading reaction is completed, the viscosity reduction rate of heavy oil feedstock is ≥99%, the desulfurization rate is ≥65%, the denitrification rate is ≥55%, and the demetallization rate is ≥96%.

[0038] In an optional embodiment, the first catalyst comprises a demetallizing agent and a desulfurizing and denitrifying agent in a mass ratio of (1–5):(1–3), wherein the demetallizing agent and the desulfurizing and denitrifying agent each independently comprise an active component and a first support, the active component being selected from at least one of Ni–Mo, Ni–W and Co–Mo, and the first support being selected from at least one of Al2O3, SiO2 and SiO2–Al2O3.

[0039] It should be noted that during the upgrading of heavy oil by methane, the demetallizing agent and the desulfurizing and denitrifying agent are loaded sequentially along the direction of the reaction stream in the first methane reactor.

[0040] In an optional embodiment, the first catalyst is pre-sulfurized, pre-reduced, or activated in a hydrogen or methane / hydrogen mixed atmosphere at 300°C–380°C before use to form the active phase required for metal trapping and hydrocracking.

[0041] It should be noted that the first catalyst in this invention is a commercially available catalyst, and its specific active components and first support can be reasonably adjusted according to actual needs. For example, the composition of the first catalyst can be selected from the following: Ni–Mo / Al2O3, Ni–Mo / SiO2, Ni–Mo / SiO2–Al2O3, Ni–W / Al2O3, Ni–W / SiO2, Ni–W / SiO2–Al2O3, Co–Mo / Al2O3, Co–Mo / SiO2, and Co–Mo / SiO2–Al2O3.

[0042] In an optional embodiment, the second catalyst includes a composite active component and a second support, wherein the composite active component is selected from at least one of a methane activating component, a regulating component, and a desulfurization and denitrification promoting component and / or a demetallization auxiliary component; and the second support is selected from at least one of SiO2, Al2O3, SiO2–Al2O3, ZSM–5, β zeolite, and USY zeolite.

[0043] Furthermore, the methane activating component is selected from at least one of Ag, Ni, Co, Ru and Rh; the oxygen migration, electronic structure or acid-base property regulating component is selected from at least one of Ce, Ga and Zn; and the desulfurization and denitrification promoting component and / or demetallization auxiliary component is selected from at least one of Mo, W, Ni and Co.

[0044] Furthermore, the precursor of the composite active component is selected from nitrates, chlorides, sulfates, or combinations thereof.

[0045] Furthermore, the mass percentage of each metal element in the second catalyst, in its oxide form, includes the following components: Rh: 0.1 wt%–5 wt%; Ga: 0.5 wt%–10 wt%; Ni: 5 wt%–20 wt%; Ce: 1 wt%–8 wt%; W: 5 wt%–10 wt%; the balance being the support.

[0046] Furthermore, the mass percentage of each metal element in the second catalyst, in its oxide form, also includes at least one of the following: Ag: 0.1 wt%–5 wt%; Ru: 0.1 wt%–5 wt%; Mo: 1 wt%–10 wt% and Zn: 5 wt%–20 wt%.

[0047] In an optional embodiment, the preparation of the second catalyst includes the following steps: A metal precursor solution is prepared by mixing the methane activating component, regulating component, desulfurization and denitrification promoting component, and / or demetallization auxiliary component with an aqueous ethanol solution in a certain proportion; the volume fraction of ethanol in the aqueous ethanol solution is 40%–60%. The second carrier, which has been pre-dried at 80℃–130℃, is placed in a metal precursor solution for immersion treatment using an equal-volume impregnation method. After the impregnation treatment, the system was aged at 20℃–50℃ for 2 h–24 h. After the aging treatment, dry at 80℃–130℃ for 4 h–24 h; After drying, the temperature was increased to 450℃–650℃ in air at a heating rate of 1.5℃ / min–4.5℃ / min and calcined for 2 h–8 h to obtain the metal oxide precursor. The metal oxide precursor was subjected to reduction activation treatment at 400℃–750℃ for 2 h–12 h in a hydrogen or hydrogen / nitrogen mixed atmosphere.

[0048] It should be noted that impregnation treatment facilitates the uniform loading of the metal precursor solution onto the carrier surface. The equal-volume impregnation method is simple, efficient, easy to directionally design, and ensures the loading of the second active component and the repeatability of the impregnation treatment.

[0049] The metal oxide precursor is reduced and activated to obtain a second catalyst. After reduction and activation, the second catalyst has good methane-directed activation ability, anti-carbon deposition performance and macromolecular residue oil diffusion ability. It is the core material for realizing the two-stage residue oil methane-induced synergistic upgrading method of the present invention.

[0050] In a second aspect, the present invention provides a two-stage heavy oil methane upgrading system for implementing the heavy oil methane upgrading method as described in any of the foregoing embodiments. The upgrading system includes a first reactor, a second reactor, a separation and circulation unit, an oxygen supply system, a feed gas supply system, and an oil collection unit; The oxygen supply system provides oxygen to the quality improvement system and participates in the in-situ heating in the second reactor. The feed gas supply system provides the upgrading system with a methane atmosphere or a methane / hydrogen mixed atmosphere. It should be noted that the first reactor and the second reactor are functionally limited to poisoning control and directed methane activation, respectively. The mixed atmosphere supply system can choose to provide a methane and hydrogen mixed atmosphere or a pure methane atmosphere, depending on the needs.

[0051] The separation and recycling unit separates the upgraded light gas from the oil. The light gas (mainly methane and a small amount of cracked gas) can be partially recycled back to the second reactor for reuse, improving resource utilization. The oil, as a deep-upgraded product, is then transported to the oil recovery unit. The features and performance of the invention are further described in detail below with reference to embodiments.

[0052] Example 1 This embodiment provides a two-stage method for upgrading heavy oil containing methane, which includes the following steps: (1) Preparation of the second catalyst Weigh out 2.6 g rhodium chloroacetic acid, 7.5 g gallium nitrate, 39 g nickel nitrate hexahydrate, 9.5 g ammonium metatungstate and 4.7 g cerium nitrate hexahydrate according to the proportions, add them to anhydrous ethanol aqueous solution (the volume ratio of anhydrous ethanol and deionized water is 1:1), stir at room temperature until completely dissolved to form a uniform and transparent metal precursor solution.

[0053] Weigh 100 g of ZSM-5 carrier that has been dried at 120°C, and slowly add the metal precursor solution to the surface of the carrier by means of equal volume impregnation while stirring for 2 h.

[0054] After impregnation, the system was aged at room temperature for 8 h and dried at 100℃ for 12 h. After drying, it was calcined at 550℃ for 4 h in air atmosphere at a rate of 2℃ / min to obtain the metal oxide precursor.

[0055] The metal oxide precursor was reduced and activated at 650°C in a hydrogen atmosphere for 6 h to obtain the second catalyst, which was Rh–Ga–Ni–W–Ce / ZSM–5.

[0056] (2) Two-stage heavy oil methane upgrading method The vacuum residue feedstock is filtered, heated, and homogenized to remove mechanical impurities and improve its fluidity, while controlling the water content to below 0.1 wt%, to obtain pretreated feedstock oil.

[0057] The pretreated feedstock oil is fed to the first reactor for pretreatment reaction to obtain intermediate oil products. The first reactor is filled with commercial desulfurization, denitrification, and demetallization agents. The pretreatment reaction is carried out at a temperature of 380℃, a pressure of 10 MPa, and a volume hourly space velocity of 0.5 h⁻¹. -1 The mixed atmosphere has a CH4 / H2 ratio of 80 / 20.

[0058] The intermediate oil product is transported from the outlet of the first reactor to the first inlet of the second reactor for upgrading reaction. During this process, 0.05 vol% oxygen is introduced to provide in-situ heating for the upgrading reaction. The second reactor is filled with the second catalyst prepared in step (1). The upgrading reaction temperature is 410℃, the pressure is 8 MPa, and the volume hourly space velocity is 0.2 h⁻¹. -1 A 100% methane atmosphere is used, with oxygen premixed with methane and introduced together.

[0059] After 48 hours of reaction, the product from the second reactor is transported from the outlet of the second reactor to the separation and circulation unit via the inlet. The light gas separated in the separation and circulation unit is returned to the second reactor for recycling, while the oil is transported to the oil recovery unit.

[0060] The obtained oil was sampled and tested, and the test results are summarized in Table 1.

[0061] Example 2 This embodiment provides a two-stage method for upgrading heavy oil containing methane. The upgrading method includes the following steps, and its difference from Example 1 lies only in the following: (2) Two-stage heavy oil methane upgrading method In the first reactor, the mixed atmosphere CH4 / H2 = 100 / 0.

[0062] Example 3 This embodiment provides a two-stage method for upgrading heavy oil containing methane. The upgrading method includes the following steps, and its difference from Example 1 lies only in the following: (1) Preparation of the second catalyst The second catalyst was prepared by replacing ammonium tungstate with 10.97 g of ammonium heptamolybdate tetrahydrate, while keeping the amounts of other substances unchanged. The catalyst was named Rh–Ga–Ni–Mo–Ce / ZSM–5.

[0063] Example 4 This embodiment provides a two-stage method for upgrading heavy oil containing methane. The upgrading method includes the following steps, and its difference from Example 1 lies only in the following: (1) Preparation of the second catalyst The second catalyst was prepared by replacing the raw material rhodium chloroacetic acid with 1.60 g of silver nitrate, while keeping the amounts of other substances unchanged. The catalyst was named Ag–Ga–Ni–W–Ce / ZSM–5.

[0064] Example 5 This embodiment provides a two-stage method for upgrading heavy oil containing methane. The upgrading method includes the following steps, and its difference from Example 1 lies only in the following: (2) Two-stage heavy oil methane upgrading method In the second reactor, the upgrading reaction was carried out at a temperature of 410℃, a pressure of 6 MPa, and a volume hourly space velocity of 0.5 h⁻¹. -1 It operates under a 100% methane atmosphere, with 0.04 vol% oxygen premixed with methane and introduced together.

[0065] Example 6 This embodiment provides a two-stage method for upgrading heavy oil containing methane. The upgrading method includes the following steps, and its difference from Example 1 lies only in the following: (2) Two-stage heavy oil methane upgrading method In the first reactor, the pretreatment reaction was carried out at a temperature of 360℃, a pressure of 9 MPa, and a volume hourly space velocity of 0.4 h⁻¹. -1 .

[0066] The upgrading reaction in the second reactor was carried out at a temperature of 410℃, a pressure of 6 MPa, and a volume hourly space velocity of 0.2 h⁻¹. -1 It operates under a 100% methane atmosphere, with 0.04 vol% oxygen premixed with methane and introduced together.

[0067] Example 7 This embodiment provides a two-stage method for upgrading heavy oil containing methane. The upgrading method includes the following steps, and its difference from Example 1 lies only in the following: (2) Two-stage heavy oil methane upgrading method In the second reactor, 0.03 vol% oxygen is introduced during the upgrading reaction to provide in-situ heating for the upgrading reaction.

[0068] Example 8 This embodiment provides a two-stage method for upgrading heavy oil containing methane. The upgrading method includes the following steps, and its difference from Example 1 lies only in the following: (2) Two-stage heavy oil methane upgrading method In the second reactor, the pressure of the upgrading reaction is 6 MPa.

[0069] Comparative Example 1 This comparative example provides a method for upgrading heavy oil containing methane. This upgrading method includes the following steps, and its difference from Example 1 lies only in: (2) Two-stage heavy oil methane upgrading method The first reactor is missing for pretreatment reaction.

[0070] The feedstock oil is directly transported to the second reactor for upgrading.

[0071] Comparative Example 2 This comparative example provides a method for upgrading heavy oil containing methane. This upgrading method includes the following steps, and its difference from Example 1 lies only in: (2) Two-stage heavy oil methane upgrading method The second upgrading reaction is missing, so the product from the first reactor is directly analyzed.

[0072] Comparative Example 3 This comparative example provides a two-stage method for upgrading heavy oil to form methane. The upgrading method includes the following steps, and its difference from Example 1 lies only in the following: (2) Two-stage heavy oil methane upgrading method The second reactor performs the upgrading reaction without introducing oxygen and provides in-situ heating.

[0073] Comparative Example 4 This comparative example provides a method for upgrading heavy oil containing methane. This upgrading method includes the following steps, and its difference from Example 1 lies only in: (2) Two-stage heavy oil methane upgrading method The first reactor is missing for pretreatment; the second reactor is used for upgrading without introducing oxygen for in-situ heating.

[0074] Comparative Example 5 This comparative example provides a two-stage method for upgrading heavy oil to form methane. The upgrading method includes the following steps, and its difference from Example 1 lies only in the following: (1) Preparation of the second catalyst The second catalyst prepared by omitting the raw material rhodium chloroacetic acid, while keeping the amounts of other substances unchanged, is denoted as Ga–Ni–W–Ce / ZSM–5.

[0075] Test Example 1 This test example samples the oils prepared in Examples 1–8 and Comparative Examples 1–5 for testing. The test items included viscosity reduction rate, desulfurization rate, denitrification rate, and demetallization rate (mainly testing for metallic nickel and vanadium). The relevant test results are summarized in Table 1, and the specific test methods for each item are as follows: The viscosity reduction rate was determined according to the national standard GB / T 11137-1989, and its calculation formula is: E=(E 前 -E 后 ) / E 前 ×100%; where E 前 E represents the viscosity of the oil before the reaction. 后 This represents the viscosity of the oil after the reaction.

[0076] The desulfurization rate passed the national standard GB / T 17040 test, and its calculation formula is: D s =(s 前 -s 后 ) / s 前 ×100%; where, s 前 s represents the total amount of sulfur before the reaction. 后This represents the total amount of sulfur after the reaction.

[0077] The nitrogen removal rate was tested according to the national standard GB / T 17674 method, and its calculation formula is: D N =(N 前 -N 后 ) / N 前 ×100%; where N 前 The total amount of nitrogen before the reaction, N 后 This represents the total amount of nitrogen after the reaction.

[0078] Table 1 Test Results

[0079] As shown in Table 1, Examples 1–8 all exhibited excellent and stable upgrading effects under different operating conditions and catalyst systems. The viscosity reduction rate was higher than 96%, the desulfurization rate was stably distributed in the range of 67.8%–73.6%, the denitrification rate was distributed in the range of 55.6%–64.5%, and the demetallization rate was higher than 96.6%. This indicates that the two-stage heavy oil methane upgrading method proposed in this invention has good adaptability and stability under different process windows.

[0080] In contrast, Comparative Example 1, which lacked the first reactor, had viscosity reduction, desulfurization, denitrification, and demetallization rates of only 91.4%, 51.2%, 38.6%, and 65.2%, respectively, which were significantly lower than those of Examples 1–8. This indicates that without the pretreatment reaction in the first reactor, metal impurities and asphaltenes in the heavy oil directly enter the second reactor. These impurities not only cover the active sites of the second catalyst and promote deposition and carbon buildup on its surface, but also weaken the metal capture and removal process, resulting in a significant decrease in the demetallization rate. This inhibits the methane activation process and leads to a significant decline in the overall upgrading effect.

[0081] In contrast, Comparative Example 2, which only retained the pretreatment reaction in the first reactor and lacked the upgrading reaction in the second reactor, achieved viscosity reduction, desulfurization, denitrification, and demetallization rates of only 85.3%, 30.6%, 19.7%, and 52.3%, respectively. The overall upgrading effect was significantly lower than that of Examples 1–8. This result indicates that while relying solely on the pretreatment reaction in the first reactor can remove or transform metallic impurities, gums, and asphaltenes in heavy oil to some extent, the lack of a subsequent methane-involved upgrading reaction process prevents the formation of an effective active hydrogen supply and cracking-hydrogenation synergy, thus hindering the achievement of deep desulfurization, denitrification, and effective transformation of macromolecular structures. Furthermore, due to the absence of methane-directed activation and in-situ heating processes in the second reactor, the reaction system remained at the level of traditional hydrotreating, failing to leverage the technological advantages of methane as a hydrogen source substitute, resulting in significantly limited upgrading depth and reaction efficiency.

[0082] Furthermore, comparing Comparative Example 2 with Comparative Example 1 shows that relying solely on the second reactor without pretreatment (Comparative Example 1) or performing pretreatment without subsequent quality improvement reactions (Comparative Example 2) both fail to achieve the desired quality improvement effect. This indicates that in the "two-stage functional division of labor" reaction system constructed in this invention, the poisoning control effect of the first reactor and the methane-directed activation effect of the second reactor are both indispensable, and there is a clear synergistic relationship between the two.

[0083] Comparative Example 3, with its two-stage reaction structure, did not introduce oxygen for in-situ heating. Its viscosity reduction rate, desulfurization rate, and denitrification rate were only 92.3%, 56.8%, and 46.7%, respectively, significantly lower than Example 1. This indicates that without in-situ heating, the energy required for methane activation is difficult to meet, leading to a decrease in methane activation, insufficient active hydrogen generation, and weakened desulfurization, denitrification, and viscosity reduction effects, thus limiting the desulfurization, denitrification, and macromolecular cracking reactions. However, because Comparative Example 3 still retains the pretreatment reaction in the first reactor, metallic impurities in the feedstock oil, as well as metal-enriched gums and asphaltenes, can be preferentially removed, captured, or converted before entering the second reactor, thus still exhibiting a high demetallization rate. Furthermore, the comparison between Comparative Example 1 and Comparative Example 3 shows that the demetallization effect mainly depends on the pretreatment reaction in the first reactor.

[0084] Comparative Example 4, which lacked both the pretreatment reaction of the first reactor and the in-situ heating of the second reactor, showed a further decline in its performance, indicating a significant synergistic effect between the functional division of the reactions and the limited in-situ heating.

[0085] Regarding operating conditions, Example 7 shows that even with only a reduction in oxygen consumption (from 0.05 vol% to 0.03 vol%), the system still maintains a high quality improvement efficiency, but all indicators are slightly lower than in Example 1. This indicates that excessively low oxygen consumption reduces the heating intensity, thereby inhibiting methane activation to some extent. This suggests that the amount of oxygen introduced needs to be controlled within a reasonable range to achieve the best effect. Combining Examples 5 and 8, it can be seen that when the reaction pressure in the second reactor decreases or the volume hourly space velocity increases, the viscosity reduction rate and impurity removal efficiency both decrease, indicating that higher pressure and a suitable residence time are beneficial to methane activation and hydrogen transfer reactions. Furthermore, Example 6 shows that when the reaction temperature and pressure in the first reactor decrease, the pretreatment effect weakens, thereby indirectly affecting the reaction performance of the quality improvement reaction in the second reactor, further demonstrating a clear pre- and post-reaction coupling relationship between the two stages of the reaction.

[0086] Regarding the catalyst system and reaction atmosphere, the results of Examples 1, 3-4, and Comparative Example 5 show that the Rh-containing multi-metal catalyst system has a significant advantage in promoting the activation of C–H bonds in methane, which is beneficial to improving the active hydrogen generation capacity, thereby enhancing the overall desulfurization, denitrification, and viscosity reduction effects. Meanwhile, Example 2 shows that even under a pure methane atmosphere in the first stage, the system can still maintain high upgrading performance, indicating that the present invention has a low dependence on external hydrogen, but the introduction of an appropriate amount of hydrogen helps to further improve reaction stability. In summary, the present invention, by constructing a reaction functional division structure of "first-stage poisoning control + second-stage methane directional activation" in the reaction system, and combining it with a restricted in-situ heating strategy, achieves effective synergy between methane activation, hydrogen source generation, and heavy oil upgrading processes. While significantly reducing the amount of external hydrogen used, it still achieves excellent viscosity reduction, desulfurization, denitrification, and demetallization effects, indicating that the technical solution of the present invention has good effectiveness and application potential.

[0087] In summary, this invention, through the synergistic design of functional division of reactions and limited in-situ heating, significantly improves desulfurization, denitrification, and viscosity reduction under methane-directed activation conditions while ensuring efficient demetallization. The functional division of reactions effectively alleviates the inherent contradiction of simultaneous methane activation and catalyst poisoning in existing single-stage methane-containing systems, constructing stable reaction preconditions that are difficult to achieve in single-stage systems. It achieves synergy between methane activation, hydrogen source generation, and reaction stability; it helps reduce the rate of carbon deposition and inhibits activity decay, resulting in a more stable reaction process that can maintain stable quality improvement over a longer operating period; and it significantly reduces the amount of externally added hydrogen while simultaneously reducing viscosity, residual carbon, and asphaltenes content, balancing quality improvement depth with operational economy, demonstrating good engineering scale-up potential and industrial application value.

[0088] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A two-stage method for upgrading heavy oil to form methane, characterized in that, The quality improvement method includes the following steps: Heavy oil feedstock is introduced into the first reactor and pretreated in a methane atmosphere or a methane / hydrogen mixed atmosphere to reduce the influence of metal impurities and / or asphaltenes on the catalyst, thereby producing intermediate oil. The intermediate oil is directly introduced into the second reactor, where it is contacted with the second catalyst under a methane atmosphere to carry out an upgrading reaction. Oxygen is introduced during the reaction for in-situ heating to promote the participation of methane in the reaction and enhance the upgrading effect.

2. The quality improvement method according to claim 1, characterized in that, In the upgrading reaction, the amount of oxygen introduced is 0.01 vol%–1 vol% of the amount of methane used. Preferably, the amount of oxygen introduced is 0.01 vol%–0.1 vol% of the amount of methane used. More preferably, the amount of oxygen introduced is 0.01 vol%–0.05 vol% of the amount of methane used.

3. The quality improvement method according to claim 1, characterized in that, The method of introducing oxygen is selected from any of the following: Option 1: Introduce the mixture into the second reactor after premixing it with methane; Method 2: Introduced through an independent gas path at the inlet of the second reactor; Method 3: Introduced into the upper part of the second reactor bed via an independent gas path.

4. The quality improvement method according to claim 1, characterized in that, When the atmosphere of the pretreatment reaction is a mixture of methane and hydrogen, the volume fraction of hydrogen is 5%–50%. Preferably, the volume fraction of the hydrogen gas is 10%–30%; And / or, the heavy oil feedstock is selected from at least one of oil sands, heavy oil, extra-heavy oil, atmospheric residue, and vacuum residue.

5. The quality improvement method according to claim 1, characterized in that, The pretreatment reaction was carried out at a temperature of 340℃–420℃, a pressure of 3 MPa–15 MPa, and a volume hourly space velocity of 0.1 h⁻¹. -1 –1.0 h -1 Preferably, the pretreatment reaction is carried out at a temperature of 360℃–400℃, a pressure of 6 MPa–12 MPa, and a volume hourly space velocity of 0.1 h⁻¹. -1 –0.5 h -1 ; And / or, the upgrading reaction is carried out at a temperature of 350℃–450℃, a pressure of 5 MPa–12 MPa, and a volume hourly space velocity of 0.1 h⁻¹. -1 –1.0 h -1 Preferably, the upgrading reaction is carried out at a temperature of 380℃–420℃, a pressure of 6 MPa–10 MPa, and a volume hourly space velocity of 0.1 h⁻¹. -1 –0.3 h -1 .

6. The quality improvement method according to claim 1, characterized in that, After the upgrading reaction is completed, the viscosity reduction rate of the heavy oil feedstock is ≥95%, the desulfurization rate is ≥60%, the denitrification rate is ≥50%, and the demetallization rate is ≥95%, wherein the removed metal is selected from at least one of nickel, vanadium, calcium, sodium, iron, and magnesium. Preferably, after the upgrading reaction is completed, the viscosity reduction rate of the heavy oil feedstock is ≥99%, the desulfurization rate is ≥65%, the denitrification rate is ≥55%, and the demetallization rate is ≥96%.

7. The quality improvement method according to claim 1, characterized in that, The first catalyst comprises a demetallizing agent and a desulfurizing and denitrifying agent, with a mass ratio of (1–5):(1–3). The demetallizing agent and the desulfurizing and denitrifying agent each independently include an active component and a first support. The active component is selected from at least one of Ni–Mo, Ni–W and Co–Mo, and the first support is selected from at least one of Al2O3, SiO2 and SiO2–Al2O3.

8. The quality improvement method according to claim 1, characterized in that, The second catalyst comprises a composite active component and a second support, wherein the composite active component comprises at least one of a methane activating component, a regulating component, and a desulfurization and denitrification promoting component and / or a demetallization auxiliary component; the second support is selected from at least one of SiO2, Al2O3, SiO2–Al2O3, ZSM–5, β zeolite, and USY zeolite. Preferably, the methane activating component is selected from at least one of Ag, Ni, Co, Ru, and Rh; the regulating component is selected from at least one of Ce, Ga, and Zn; and the desulfurization and denitrification promoting component and / or demetallization auxiliary component is selected from at least one of Mo, W, Ni, and Co. Preferably, the precursor of the composite active component is selected from nitrates, chlorides, sulfates, or combinations thereof; Preferably, the mass percentage of each metal element in the second catalyst, in its oxide form, comprises the following components: Rh: 0.1 wt%–5 wt%; Ga: 0.5 wt%–10 wt%; Ni: 5 wt%–20 wt%; Ce: 1 wt%–8 wt%; W: 5 wt%–10 wt%; the balance being the support. Preferably, the mass percentage of each metal element in the second catalyst, in its oxide form, further includes at least one of the following: Ag: 0.1 wt%–5 wt%; Ru: 0.1 wt%–5 wt%; Mo: 1 wt%–10 wt% and Zn: 5 wt%–20 wt%.

9. The quality improvement method according to claim 8, characterized in that, The preparation of the second catalyst includes the following steps: The precursors of the methane activating component, the regulating component, and the desulfurization and denitrification promoting component and / or demetallization auxiliary component are mixed with an aqueous ethanol solution in a certain proportion to prepare a metal precursor solution. The volume fraction of ethanol in the ethanol-water solution is 40%–60%. The second carrier, which has been pre-dried at 80℃–130℃, is placed in the metal precursor solution for immersion treatment using an equal-volume immersion method. After the impregnation treatment, the system was aged at 20℃–50℃ for 2 h–24 h. After the aging treatment, dry at 80℃–130℃ for 4 h–24 h; After drying, the temperature was increased to 450℃–650℃ in air at a heating rate of 1.5℃ / min–4.5℃ / min and calcined for 2 h–8 h to obtain the metal oxide precursor. The metal oxide precursor was subjected to reduction activation treatment at 400℃–750℃ for 2 h–12 h in a hydrogen or hydrogen / nitrogen mixed atmosphere.

10. A two-stage heavy oil methane upgrading system, characterized in that, Used for implementing the method for upgrading heavy oil with methane as described in any one of claims 1–9; The upgrading system includes a first reactor, a second reactor, a separation and circulation unit, an oxygen supply system, a feed gas supply system, and an oil collection unit. The oxygen supply system provides oxygen to the quality improvement system and participates in the in-situ heating in the second reactor; The feed gas supply system provides the upgrading system with a methane atmosphere or a methane / hydrogen mixed atmosphere.

Images