A de-ironing reduction catalyst, its preparation method and use

Abstract

The present application relates to a kind of deironing reduction catalyst and its preparation method and purposes.The catalyst uses alumina, silicon oxide as carrier, uses cobalt, EDTA as active component, uses potassium and phosphorus as auxiliary agent.The catalyst preparation process is simple, and preparation process is without secondary pollution.The catalyst specific surface area is greater than 150m 2 / g, pore volume is greater than 0.30mL / g, the pore of 30nm above accounts for more than 25%, catalyst SO3 reduction rate is greater than 99%, iron capacity is greater than 25%.The catalyst is loaded in the top of the first reactor of the sulfur recovery device for processing alkylated waste acid, can remove SO3 and iron ion in process gas, can also replace porcelain ball, can effectively guarantee the normal operation of sulfur device, realizes alkylated waste acid introduction sulfur device processing.

Description

Technical Field

[0001] This invention belongs to the field of sulfur recovery technology, specifically relating to an iron removal reduction catalyst, its preparation method, and its applications. Background Technology

[0002] With increasingly stringent domestic environmental regulations, refining and chemical enterprises are facing immense pressure to upgrade gasoline quality, and alkylated gasoline represents the future direction of clean gasoline development. However, the waste sulfuric acid generated by alkylation units is difficult to treat, and the investment in waste acid treatment equipment accounts for 60-100% of the total investment in alkylation units, significantly increasing investment costs. Waste acid treatment severely restricts the development of alkylation technology. Developing a new method for the rational recovery of waste acid would not only have considerable economic benefits but also significant social implications.

[0003] Currently, most oil refineries in my country are equipped with 2-3 sulfur recovery units. In the sulfur production furnace of these units, the main processes involve the combustion of hydrogen sulfide and the Claus reaction between hydrogen sulfide and sulfur dioxide, with the furnace temperature controlled above 1000℃. If waste acid can be directly introduced into the sulfur production unit for treatment, the alkylation waste acid can directly enter the sulfur production furnace to decompose and generate sulfur dioxide. The sulfur dioxide then reacts with hydrogen sulfide in subsequent processes to produce sulfur, thus recovering sulfur resources. This approach offers significant advantages: First, it utilizes existing sulfur recovery units, eliminating the need for a separate waste acid recovery unit, saving investment. Second, it offers large processing capacity with minimal limitations. Third, the process is simple and generates no secondary pollution.

[0004] Waste acid cracking produces a certain amount of SO3, which enters the subsequent catalytic reaction unit along with the process gas. If SO3 is not removed in time, it will cause severe corrosion to the equipment upon condensation upon contact with water. Simultaneously, the waste acid contains a certain amount of iron ions. Most of these iron ions are carried out of the sulfur unit with the liquid sulfur, but a small amount remains and is carried into the later units, affecting the quality of the sulfur product. Therefore, it is necessary to develop an iron removal reduction catalyst to ensure complete conversion of SO3 and simultaneous removal of iron ions in the primary reactor.

[0005] CN206701071U discloses an apparatus for removing sulfur trioxide, comprising a dissolving tank, a storage tank, a dilution water tank, an SCR reactor, and an air preheater, which removes SO3 by injecting alkaline solution into the flue gas duct for absorption. The method provided by this invention improves the utilization rate of the absorbent and effectively reduces the impact on corrosion and ash accumulation on the downstream air preheater.

[0006] CN111167274B discloses a method and apparatus for removing sulfur trioxide from smelting flue gas. The method involves contacting the smelting flue gas with a reducing agent in a flue gas channel to first remove residual oxygen from the flue gas, and then reducing SO3 in the flue gas to SO2. Alternatively, the removal of oxygen from the flue gas and the reduction of SO3 can be carried out simultaneously, or SO3 in the flue gas can be selectively reduced to SO2. The reduced flue gas is then used to produce sulfuric acid.

[0007] CN111482066A discloses a method for removing SO3 from high-temperature flue gas. The method involves injecting a powdered reducing agent into the area through which the high-temperature flue gas flows in an industrial device. Under certain conditions, the powdered reducing agent mixes thoroughly with the SO3 in the flue gas and undergoes an oxidation-reduction reaction, thereby reducing SO3 emissions.

[0008] Therefore, existing technologies primarily target the removal of SO3 from high-temperature flue gas. Mainstream desulfurization processes rely on acid-base neutralization or the addition of reducing powders to the flue gas to remove SO3. In the acid-base neutralization method, SO3 reacts to form sulfates, requiring secondary treatment and causing secondary pollution. Similarly, after SO3 removal via powder reduction, secondary treatment using alkaline absorption is necessary, and the reduction removal rate is relatively low, exceeding 80%. Thus, it can be seen that existing SO3 removal technologies are mainly applied to high-temperature flue gas, have complex processes, are prone to secondary pollution, and cannot simultaneously achieve iron removal. Summary of the Invention

[0009] The purpose of this invention is to provide a deferrore reduction catalyst, its preparation method, and its uses, in order to overcome the shortcomings of the prior art.

[0010] This invention provides a deferrore reduction catalyst, wherein the catalyst uses alumina and silica as supports, cobalt and EDTA as active components, and potassium and phosphorus as auxiliary agents.

[0011] The catalyst, based on 100 parts by weight of the total catalyst, comprises the following components:

[0012]

[0013] The catalyst has a specific gravity of 1.15-1.35 g / cm³. 3 Specific surface area greater than 150m² 2 / g, pore volume greater than 0.30mL / g, and pores larger than 30nm accounting for more than 25% of the total pore volume.

[0014] The catalyst is spherical in shape with a diameter of 5-10 mm.

[0015] The catalyst has an SO3 reduction rate greater than 99% and an iron content greater than 25%.

[0016] The catalyst was prepared using the rolling ball method.

[0017] The present invention also provides a method for preparing the aforementioned iron removal reduction catalyst, comprising:

[0018] (1) After uniformly mixing silicon source, aluminum source, potassium source with pore expander and binder, the mixture is rolled into balls, cured, dried and calcined to obtain catalyst support;

[0019] (2) The catalyst support is immersed in a solution containing cobalt and phosphorus, then removed, dried and calcined to obtain the catalyst precursor;

[0020] (3) The catalyst precursor is immersed in a solution containing EDTA, then removed, dried and calcined to obtain the catalyst.

[0021] In step (1), kaolin is used as a silicon source and at least a portion of the aluminum source to introduce silicon oxide and aluminum oxide. The kaolin has a particle size greater than 1250 mesh and a density greater than 2.5 g / cm³. 3 Kaolin, as a precursor, has advantages such as low cost and high specific gravity.

[0022] In step (1), in addition to using kaolin as part of the aluminum source, boehmite is also used as another part of the aluminum source. The boehmite has a specific surface area greater than 320 m². 2 / g, pore volume greater than 0.50mL / g, preferably specific surface area greater than 350m² 2 / g and pore volume greater than 0.60mL / g are used to ensure that the prepared catalyst has a high specific surface area and sufficient active sites to improve the deironization and reducibility of the catalyst.

[0023] In step (1), potassium oxide is introduced by using an inorganic salt of potassium as a potassium source. The inorganic salt of potassium includes one or more of potassium carbonate, potassium bicarbonate, potassium chloride, and potassium sulfate, with potassium carbonate and potassium bicarbonate being preferred.

[0024] In step (1), the pore-expanding agent is at least one of guar gum powder, polyvinyl alcohol, carboxymethyl cellulose, starch, carbon black, etc., preferably guar gum powder.

[0025] In step (1), the amount of pore-expanding agent added is 2-6 parts, preferably 3-5 parts, based on 100 parts by weight of the total catalyst. The pore-expanding agent is burned off during the calcination of the support to provide pores for the catalyst.

[0026] In step (1), the adhesive is one of nitric acid, acetic acid, citric acid or sulfuric acid, preferably acetic acid.

[0027] In step (1), the amount of binder added is 2-5 parts, preferably 2.5-4 parts, based on 100 parts by weight of the total catalyst. The binder can enhance the strength of the catalyst.

[0028] Step (1) further includes the following steps:

[0029] (1.1) Mix the silicon source, aluminum source, potassium source and pore expander evenly to form a solid material;

[0030] (1.2) Add the adhesive to water and stir until homogeneous to prepare the first solution;

[0031] (1.3) Ball rolling: The solid material obtained in step (1.1) is placed in a ball rolling machine, and then a first solution is applied to the material in the ball rolling machine. The ball rolling is rotated to form spherical particles with a certain diameter. Then the rotation is stopped, the spherical particles are sieved, and small balls with the first diameter are taken out.

[0032] (1.4) The small balls obtained in step (1.3) are aged, dried and calcined in a steam atmosphere to obtain the catalyst support.

[0033] In step (1.3), the first solution is applied by spraying the first solution.

[0034] In step (1.3), the first diameter is 5-10 mm.

[0035] In step (1.4), the curing temperature is 80-100℃ and the curing time is 10-25h.

[0036] In step (1.4), the drying temperature of the small balls is 80-160℃ and the drying time is 3-8h.

[0037] In step (1.4), the calcination temperature of the small balls is 380-550℃, preferably 380-450℃; the calcination time is 3-10h, preferably 4-6h.

[0038] In step (2), phosphorus is introduced into the solution in the form of phosphoric acid, which can act as an auxiliary agent and increase the strength of the catalyst.

[0039] In step (2), cobalt is introduced into the solution in the form of a soluble cobalt salt, wherein the cobalt salt is selected from one or more of cobalt chloride, basic cobalt carbonate, cobalt nitrate, etc.

[0040] In step (2), the soaking time is 30 min to 3 h, preferably 1 to 2.5 h.

[0041] In step (2), the drying is called baking, the baking temperature is 100-160℃, preferably 120-140℃, and the baking time is 3-8h, preferably 3-5h.

[0042] In step (2), the roasting temperature is 360-600℃, preferably 400-500℃, and the roasting time is 3-8h, preferably 4-6h.

[0043] In step (3), EDTA is introduced into the solution in the form of disodium EDTA.

[0044] In step (3), the soaking time is 30 min to 3 h, preferably 1 to 2.5 h.

[0045] In step (3), the drying is called baking, the baking temperature is 80-130℃, preferably 100-120℃, and the baking time is 3-8h, preferably 3-5h.

[0046] In step (3), the roasting temperature is 180-230℃, preferably 200-220℃, and the roasting time is 3-8h, preferably 4-6h.

[0047] The present invention also provides the use of the iron removal reduction catalyst in a sulfur recovery unit.

[0048] The iron removal reduction catalyst is packed at the top of the primary reactor of the sulfur recovery unit for treating alkylation waste acid.

[0049] The beneficial effects of this invention are as follows:

[0050] (1) The catalyst of the present invention is used in the primary reactor of a sulfur recovery unit for treating alkylation waste acid. It is packed in the upper part of the primary reactor and has a hydrogenation reduction function, capable of converting SO3 in the process gas into SO2, ensuring the long-term stable operation of the sulfur recovery unit. Simultaneously, the catalyst possesses good iron removal and iron-dissolving properties, enabling the deposition of iron ions carried in the waste acid within the catalyst pores. Specifically:

[0051] Under the conditions that the SO3 content in the process gas at the reactor inlet is less than 1000 ppm, the iron ion content is less than 800 ppm, and the bed temperature is 290-320℃, the catalyst of this invention has an SO3 reduction rate of greater than 99% and an iron content of greater than 25%, which can enable the introduction of alkylation waste acid into the sulfur recovery unit for treatment, thus solving the problem of alkylation waste acid treatment. At the same time, the catalyst has a larger specific gravity and can be used to replace ceramic balls, thereby reducing the impact of the introduction of alkylation waste acid on the sulfur unit and ensuring the normal operation of the sulfur unit.

[0052] When the catalyst of this invention is loaded into the primary reactor of the sulfur plant, SO3 reacts with reducing gases such as hydrogen and CO in the process gas under the action of the catalyst to generate SO2, which can simultaneously reduce CO emissions from the flue gas of the sulfur plant.

[0053] When the catalyst of this invention is loaded into sulfur processing equipment and reactors, it also possesses certain Claus and hydrolysis activities, which can effectively ensure the sulfur conversion rate of the equipment.

[0054] (2) The catalyst of the present invention uses a silicon-aluminum composite support. On the one hand, alumina can ensure that the catalyst has a certain Claus activity and ensure the sulfur conversion rate of the whole device; on the other hand, SiO2 can ensure that the catalyst has a high specific gravity and strength, and can be filled on the top of the reactor to replace ceramic balls, thereby further reducing the impact on the sulfur conversion rate of the whole device.

[0055] (3) The catalyst of the present invention uses cobalt as the active component, which can enable the catalyst to have appropriate hydrogenation reduction activity, ensuring SO3 reduction while avoiding hydrogenation reaction of other components.

[0056] (4) The catalyst of the present invention also uses EDTA as an active component, which can promote the adsorption of iron by the catalyst and increase the de-ironing ability of the catalyst.

[0057] (5) The catalyst of the present invention uses potassium as an auxiliary agent, which can enable the catalyst to have a certain ability to hydrolyze organic sulfur, promote the hydrolysis reaction of organic sulfur in the device, and reduce the impact on the sulfur conversion rate of the whole device; on the other hand, it can effectively improve the strength of the catalyst.

[0058] (6) The catalyst of the present invention also uses phosphorus as an auxiliary agent, which can effectively increase the dispersion of the active component and improve the activity of the catalyst.

[0059] (7) The preparation method of the iron removal reduction catalyst of the present invention is scientific, reasonable, simple and easy to implement, and the preparation process is free from secondary pollution.

[0060] (8) In the preparation process of the catalyst of the present invention, the content of macropores in the catalyst can be effectively increased by adding a pore expander and calcining at high temperature multiple times, wherein the pores with a diameter of 30 nm or more account for more than 25%.

[0061] (9) In the preparation of the catalyst of the present invention, the active component EDTA is added separately by a two-stage impregnation method. This can avoid the active component cobalt from being complexed and losing its catalytic activity. On the other hand, the two-stage impregnation and two-stage calcination can further improve the catalyst strength and increase the catalyst pore size while effectively ensuring the activity of EDTA.

[0062] (10) The present invention also provides an application of a de-iron reduction catalyst, which is used in a sulfur plant to introduce alkylation waste acid into the sulfur plant for treatment, providing a simple, pollution-free and low-investment treatment method for alkylation waste acid. Brief description of the attached figures

[0063] Figure 1 This is a flow chart of the preparation process of the catalyst described in this invention;

[0064] Figure 2 This is a flowchart of a laboratory catalyst activity evaluation device. Detailed Implementation

[0065] The present invention will now be described in further detail with reference to specific embodiments. However, it should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the claims of this application.

[0066] Example 1

[0067] Weigh out 652.17 grams of material with a particle size of 1500 mesh and a specific gravity of 3.0 g / m³. 3 Kaolin, 506.35 g / m², specific surface area 378 m² 2 A mixture of 0.76 mL / g boehmite, 59.27 g of 99% pure potassium carbonate, and 30.30 g of 99% pure guar gum powder was prepared. 30 g of acetic acid was weighed and added to 100 g of deionized water, and stirred until homogeneous to prepare the first solution. The homogeneous solid material was placed in a ball-forming machine, and the first solution was sprayed onto the material. The ball-forming process continued until small balls with a diameter of Φ5–10 mm were formed. The rotation was stopped, and the spherical particles were sieved to obtain the small balls with a diameter of Φ5–10 mm. The small balls were then aged in a steam atmosphere at 80℃ for 16 hours, dried at 120℃ for 6 hours, and calcined at 520℃ for 5 hours to obtain the catalyst support.

[0068] 62.92g of basic cobalt carbonate and 13.79g of phosphoric acid were added to deionized water and stirred until a stable solution B was formed. The carrier was impregnated by the equal volume impregnation method for 1.5h. The prepared semi-finished catalyst was dried at 130℃ for 4h and calcined at 450℃ for 5h to obtain the catalyst precursor.

[0069] Weigh 44.28g of disodium ethylenediaminetetraacetate (dihydrate), dissolve it in deionized water and stir until a stable solution C is formed. Impregnate the catalyst precursor using the equal volume impregnation method for 1.5h. Then remove it and dry it at 110℃ for 4h and calcine it at 210℃ for 5h to obtain the catalyst.

[0070] The catalyst prepared has a specific surface area of ​​175 m². 2 / g, pore volume 0.33mL / g, macropores larger than 30nm account for 34.6%, specific gravity 1.31g / cm³ 3 .

[0071] Examples 2-7

[0072] Activated carbon catalysts were prepared according to the steps of Example 1, except that the contents of different components were varied, as detailed in Table 1.

[0073] Table 1 Catalyst composition of the examples (unit: parts by weight)

[0074] Example 1 4.0 2.0 1.0 4.0 30 margin Example 2 3.0 1.0 0.5 2.0 20 margin Example 3 5.0 3.0 1.5 5.0 35 margin Example 4 3.5 1.5 0.8 3.0 25 margin Example 5 4.5 2.5 1.2 2.5 28 margin Example 6 3.3 1.7 0.9 3.5 32 margin Example 7 4.7 3.0 1.0 4.5 30 margin

[0075] Comparative Examples 1-5

[0076] The catalyst was prepared according to the steps and conditions of Example 1, except that the content of different components was changed, as detailed in Table 2.

[0077] Table 2 Comparative Catalyst Composition

[0078] Comparative Example 1 0 2.0 1.0 4.0 30 margin Comparative Example 2 4.0 0 1.0 4.0 30 margin Comparative Example 3 4.0 2.0 0 4.0 30 margin Comparative Example 4 4.0 2.0 1.0 0 30 margin Comparative Example 5 4.0 2.0 1.0 4.0 0 margin

[0079] Catalyst evaluation methods

[0080] The microreactor's reactor is constructed from a 20mm inner diameter stainless steel tube and is placed inside a constant temperature chamber. The catalyst loading is 10ml, and the top is filled with quartz sand of the same particle size for mixing and preheating. Rapid test strips are used to detect the SO3 content in the inlet and outlet gases.

[0081] The inlet gas composition is 3% H2 (or CO), 0.1% SO3, 500 ppm iron ions, and the remainder is N2, with a gas hourly space velocity of 3000 h⁻¹. -1 The reaction temperature is 300℃.

[0082] The SO3 removal rate ηso3 of the catalyst is calculated according to the following formula:

[0083]

[0084] N0 and N1 represent the volume concentrations of SO3 at the inlet and outlet, respectively.

[0085] The specific surface area and pore volume of the catalysts prepared in Examples 1-7 and Comparative Examples 1-5 were determined according to the method of GB / T6609.35-2009, and the catalyst activity was evaluated according to the catalyst evaluation method described above. The specific data are shown in Table 3.

[0086] Table 3. Catalyst physicochemical properties and catalytic activity data

[0087]

[0088]

[0089] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A deferrore reduction catalyst, wherein the catalyst uses alumina and silica as supports, cobalt and EDTA as active components, and potassium and phosphorus as promoters. in, Based on a total catalyst weight of 100 parts by weight, the catalyst comprises the following components: 20-35 servings; 3-5 parts K2O; 0.5-1.5 portions; EDTA 2-5 parts; CoO 1-3 parts; Al2O3 balance; The catalyst has a specific surface area greater than 150 m². 2 The catalyst has a pore volume greater than 0.30 mL / g, with pores larger than 30 nm accounting for more than 25% of the total pore volume; the catalyst is prepared using the rolling ball method. The preparation method of the iron removal reduction catalyst includes: (1) After uniformly mixing silicon source, aluminum source, potassium source with pore expander and binder, the mixture is rolled into balls, cured, dried and calcined to obtain catalyst support; (2) The catalyst support is immersed in a solution containing cobalt and phosphorus, then removed, dried and calcined to obtain the catalyst precursor; (3) The catalyst precursor is immersed in a solution containing EDTA, then removed, dried and calcined to obtain the catalyst; the calcination temperature is 180-230℃ and the calcination time is 3-8h.

2. A method for preparing the iron removal reduction catalyst as described in claim 1, comprising: (1) After uniformly mixing silicon source, aluminum source, potassium source with pore expander and binder, the mixture is rolled into balls, cured, dried and calcined to obtain catalyst support; (2) The catalyst support is immersed in a solution containing cobalt and phosphorus, then removed, dried and calcined to obtain the catalyst precursor; (3) The catalyst precursor is immersed in a solution containing EDTA, then removed, dried and calcined to obtain the catalyst; the calcination temperature is 180-230℃ and the calcination time is 3-8h.

3. The method for preparing the iron removal reduction catalyst as described in claim 2, wherein, In step (1), kaolin is used as the silicon source and at least part of the aluminum source, boehmite is used as another part of the aluminum source, and potassium inorganic salt is used as the potassium source.

4. The method for preparing the iron removal reduction catalyst as described in claim 2, wherein, Step (1) further includes the following steps: (1.1) Mix the silicon source, aluminum source, potassium source and pore expander evenly to form a solid material; (1.2) Add the adhesive to water and stir until homogeneous to prepare the first solution; (1.3) Ball rolling: The solid material obtained in step (1.1) is placed in a ball rolling machine, and then a first solution is applied to the material in the ball rolling machine. The ball rolling is rotated to form spherical particles with a certain diameter. Then the rotation is stopped, the spherical particles are sieved, and small balls with the first diameter are taken out. (1.4) The small balls obtained in step (1.3) are aged, dried and calcined in a steam atmosphere to obtain the catalyst support.

5. The method for preparing the iron removal reduction catalyst as described in claim 2, wherein, In step (2), the roasting temperature is 360-600℃ and the roasting time is 3-8h.

6. Use of the iron removal reduction catalyst as described in claim 1 in a sulfur recovery unit.

7. The use according to claim 6, wherein, The iron removal reduction catalyst is packed at the top of the primary reactor of the sulfur recovery unit that processes alkylation waste acid.

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