Denitration combustion improver for full regeneration process of catalytic cracking unit and preparation method thereof

Abstract

The present application belongs to the technical field of denitration combustion improver, and particularly relates to a denitration combustion improver for a complete regeneration process of a catalytic cracking device and a preparation method thereof. The preparation method of the denitration combustion improver is as follows: a gamma-Al2O3 precursor and a siloxane copolymer are mixed, spray granulation, drying, calcination and in-situ modification with an alkali solution are performed to obtain an in-situ modified silicon-aluminum compound; then the silicon-aluminum compound is immersed in an aqueous solution of a phosphoric acid compound for impregnation, and is dried and calcined to obtain a phosphorus-oxygen-silicon-aluminum compound; then the phosphorus-oxygen-silicon-aluminum compound is immersed in an aqueous solution of a noble metal inorganic compound and a metal organic compound for impregnation, and is dried and calcined to obtain a denitration combustion improver semi-product; finally, an organic chelating agent is uniformly sprayed on the denitration combustion improver semi-product under negative pressure, and the denitration combustion improver semi-product is dried and calcined to obtain the denitration combustion improver. The denitration combustion improver prepared by the present application has the effects of efficient denitration and elimination of tail combustion, and can achieve a high denitration efficiency under a low addition amount, has a significant economic benefit and is safe and environmentally friendly.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of denitration combustion improver, and particularly relates to a denitration combustion improver for a complete regeneration process of a catalytic cracking device and a preparation method thereof. BACKGROUND

[0002] Nitrogen oxides (NO x ) and carbon monoxide (CO) are both major atmospheric pollutants and have different degrees of toxicity, and are discharged into the atmosphere to form acid rain to destroy the atmosphere and harm the environment and human health. In the operation of a catalytic cracking device of a refinery, the proportion of NO x discharged into the atmosphere is high due to the heavy and poor quality of raw materials, so it is particularly important to study and control the NO x emission in the catalytic cracking (FCC) process; meanwhile, the heavy and poor quality of raw materials also causes intense tail combustion of the catalytic cracking device, frequent temperature overruns of the dilute phase of the regenerator and the inlet and outlet of the flue gas turbine, causes equipment burnout and increases the CO concentration in the flue gas discharged, which not only increases heat energy loss but also seriously pollutes the environment.

[0003] The catalytic cracking device of a refinery is divided into two forms of complete (oxygen-rich) regeneration and oxygen-lean regeneration process according to the combustion form. Complete regeneration refers to that the coke on the spent catalyst is basically all converted into CO2 into the regeneration flue gas after being burned in the regenerator, the excess oxygen content is 0-7%, and the CO content is extremely low; that is, excess oxygen exists in the regenerator, and the nitrogen-containing coke on the spent catalyst is mainly in the form of NO x gas after being burned. The oxygen-lean regeneration process refers to that a part of the coke on the spent catalyst is converted into CO2 and a part is converted into CO into the regeneration flue gas after being burned in the regenerator with limited oxygen content, the excess oxygen content is 0, the CO content accounts for 3-9%, the CO2 content accounts for 6-12%, and a CO incinerator must be provided in the process to fully incinerate a large amount of CO gas in the flue gas; that is, no excess oxygen exists in the regenerator, and the nitrogen-containing coke on the spent catalyst is mainly in the form of NH3 and HCN reduction gas after being burned, which is converted into NO after being fully burned in the CO incinerator.

[0004] The catalytic flue gas denitration technology of a refinery mainly includes: selective catalytic oxidation (SCR) process, selective non-catalytic reduction (SNCR) process, and low-temperature O3 oxidation (LoTO x ) process. Among them, the selective non-catalytic reduction (SNCR) process has problems of unstable and low denitration rate in actual operation due to the difficulty in guaranteeing the reaction temperature and residence time, and the average denitration rate is 30-50%. The low-temperature O3 oxidation (LoTO x ) process has problems of O3 escape destroying the atmosphere and extremely high operating energy consumption, and it only transfers NO x from atmospheric pollution to water pollution, and does not fundamentally solve the problem of NOx The problem of polluting the environment. The denitration rate of the selective catalytic reduction (SCR) process is relatively high, with an average of more than 80%, but the investment and construction cost is relatively high, and a large amount of reducing agent (liquid ammonia) is consumed during operation, and problems such as NH3 escape, salt deposition and corrosion of flue gas equipment, and ammonia nitrogen exceeding the standard in discharged wastewater are common.

[0005] In order to control the operating cost, the refinery currently generally adopts the combination of "adding denitration combustion improver (addition amount 2.5-4%) + denitration process" to carry out flue gas denitration of the complete regeneration process. By adding the denitration combustion improver, the NOx concentration in the discharged flue gas can be reduced to 200 mg / m x 3 The following, and the amount of ammonia injection is reduced, the service life of the catalyst in the denitration process module is prolonged, and the operating cost of the refinery is reduced by about 20-30%. However, most of the denitration combustion improvers that have been industrially applied on the market at present are directly prepared by using γ-Al2O3 non-spherical particles as a carrier to impregnate active metals and then calcining, and the physical and chemical indexes of the final products are limited by the indexes of the γ-Al2O3 carrier, and problems such as high wear index, small specific surface area and pore volume, and large addition amount to dilute the activity of the main catalyst exist, and the denitration effect of the existing denitration combustion improver is further reduced, and the target of completely zero ammonia injection to stop the denitration module or not to newly build a supporting SCR process unit cannot be achieved, especially on the complete regeneration fast bed device, the limiting speed in the regenerator is too high. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a denitration combustion improver for a complete regeneration process of a catalytic cracking device, which has the effects of high-efficiency denitration and elimination of tail combustion, can achieve high denitration efficiency under the condition of low addition amount, has significant economic benefits, is safe and environmentally friendly, and a preparation method thereof.

[0007] The preparation method of the denitration combustion improver for the complete regeneration process of the catalytic cracking device comprises the following steps:

[0008] (1) γ-Al2O3 precursor and siloxane copolymer are mixed, chemical water and sol agent are added, and stirring is uniformly carried out to obtain a slurry, aging is carried out, spray granulation is carried out to obtain spherical particles, then drying is carried out at a temperature of 220-280℃ for 10-20h, calcination is carried out at a temperature of 700-900℃ for 6-16h to obtain a silicon aluminum compound, and then the silicon aluminum compound is immersed in a sodium hydroxide solution, in-situ modification is carried out at 120-140℃ and 20-50kPa for 2-4h to obtain an in-situ modified silicon aluminum compound;

[0009] (2) The in-situ modified silicon aluminum compound is immersed in an aqueous solution of a phosphoric acid compound for impregnation, then drying is carried out at a temperature of 100-200℃ for 2-4h, and calcination is carried out at a temperature of 700-900℃ for 4-8h to obtain a phosphorus oxygen silicon aluminum compound.​

[0010] (3) the phosphorus oxygen silicon aluminum compound is immersed into the aqueous solution of the noble metal inorganic compound and the metal organic compound to perform impregnation, and then is dried at a temperature of 140-180 DEG C for 2-4h, and is calcined at a temperature of 700-800 DEG C for 4-6h to obtain the denitration combustion-supporting agent semi-finished product;

[0011] (4) the organic chelating agent is uniformly sprayed on the denitration combustion-supporting agent semi-finished product under negative pressure to perform stirring, and then is dried at a temperature of 160-200 DEG C for 2-4h, and is calcined at a temperature of 650-700 DEG C for 5-7h to obtain the denitration combustion-supporting agent for complete regeneration process of catalytic cracking device.

[0012] In the present application, the weight percentage of the raw materials is: the gamma-Al2O3 precursor 62-78%, the siloxane copolymer 9-15%, the noble metal inorganic compound 1-3%, the metal organic compound 4-10%, the phosphoric acid compound 4-6%, and the organic chelating agent 2-4%.

[0013] In step (1), the gamma-Al2O3 precursor is at least one of pseudo-boehmite and boehmite; and the siloxane copolymer is at least one of polyether modified siloxane copolymer and hydrophilic amino modified polysiloxane copolymer.

[0014] In step (1), the molar ratio of aluminum to silicon of the slurry is (20-200):1; the amount of water added is 25-55% of the total mass of the gamma-Al2O3 precursor and the siloxane copolymer; and the sol agent is hydrochloric acid or nitric acid solution, which is added to the slurry to a pH value of 2-4.

[0015] In step (1), the concentration of the sodium hydroxide solution is 5-10 wt.%.

[0016] In step (1), the aging temperature is 90-140 DEG C, and the aging time is 10-16h; and the spray granulation temperature is 200-250 DEG C.

[0017] In step (1), during drying and calcination, the temperature rising rate is controlled to be not greater than 50 DEG C / h to prevent the particles from deforming due to too fast dehydration and reduce the sphericity, and the calcination and in-situ modification process is a forming and pore-forming process.

[0018] In the present application, organic silicon is introduced from the source when the carrier is prepared, and an amorphous pore structure silicon aluminum compound carrier is obtained through in-situ crystallization, spray forming, calcination, and in-situ modification with alkali liquor, which has the characteristics of low wear index, high specific surface area, pore volume, and small addition amount. The amount of gas generated in the calcination process of the organic silicon itself is large and continuous and uniform, so that the obtained pore channel is rich and uniform and continuous. When the in-situ modification with alkali liquor is performed, the silicon and aluminum compounds on the surface of the pore channel react with the alkali liquor to crystallize, so that the specific surface area is larger and the pore channel is more abundant.

[0019] In step (2), the phosphoric compound is at least one of phosphoric acid, ammonium dihydrogen phosphate; the mass concentration of the phosphoric compound in the aqueous solution of the phosphoric compound is 10-20%; and the impregnation time is 12-24 hours.

[0020] The present application modifies the silicon-aluminum compound carrier by using the phosphoric compound, which can form a-P-O-Al-O-Si-O-P- network stable structure with the silicon and aluminum in the silicon-aluminum compound carrier, thereby improving the wear resistance of the carrier, avoiding the hydrothermal deactivation of the denitration combustion improver product, increasing the acid active points of the carrier, and facilitating the adsorption of part of the reducing gas in use, and improving the denitration combustion performance.

[0021] In step (3), the noble metal inorganic compound is at least one of chloropalladic acid, chlororhodic acid, and silver nitrate; and the metal organic compound is at least two of EDTA-Zn, isooctyl titanate, antimony acetate, zirconium acetate, cobalt polyphthalocyanine, neodymium acetate, and lanthanum cerium oxalate.

[0022] In the aqueous solution of the noble metal inorganic compound and the metal organic compound, the total mass concentration of the noble metal inorganic compound and the metal organic compound is 3-10%; and the impregnation time is 24-36 hours.

[0023] The present application simultaneously uses the noble metal inorganic compound and the metal organic compound as the active component, the noble metal inorganic compound is mainly used to capture and adsorb the CO, NH3 / HCN, O2, and NO x generated by the regenerated catalyst bed of the adsorber by using the strong coordination adsorption effect; and the metal organic compound is mainly used to promote the oxidation-reduction reaction.

[0024] In the operation of the catalytic cracking device, the NO x in the regenerator of the full regeneration process comes from the following sources:

[0025] NR3+O2→NO x +CO+CO2+H2O (1);

[0026] In formula (1), NR3 is nitrogen-containing coke of the spent agent, and R is an organic matter.

[0027] In the dense bed of the regenerator of the catalytic cracking device, the denitration combustion improver uses different active components to adsorb and catalyze the CO, O2, and NO x in the regenerated flue gas, promotes the oxidation of CO to generate CO2, promotes the reaction of NO x with CO and C, and promotes the reduction of NO xand reduced to N2. The specific reaction mechanism is as follows:

[0028] 2Pr + O2→ 2Pr:O (2);

[0029] Pz + CO / C→ Pz:CO / C (3);

[0030] Py + NO x → Py:NO x (4);

[0031] Pr:O + Pz:CO→ Pr + Pz + CO2 (5);

[0032] Py:NO x + Pz:CO / C→ N2↑ + CO2↑ + Pz + Py (6);

[0033] In formulae (2)-(6), Pz, Pr and Py represent different active component elements in the catalyst.

[0034] The denitration combustion improver of the present application can efficiently and selectively adsorb and regenerate the bed layer of NO x , CO and O2 components, greatly reduce the reaction activation energy and promote the catalytic oxidation-reduction reaction, convert NO x into N2 and convert CO into CO2, thereby achieving the denitration combustion efficiency.

[0035] In step (4), the organic chelating agent is at least one of citric acid, tartaric acid and tricarballylic acid.

[0036] Preferably, the denitration combustion improver semi-product is placed in a negative pressure high-efficiency spray double cone, and the organic chelating agent is uniformly sprayed in the denitration combustion improver semi-product under negative pressure, and rotated and stirred for 2-3 h.

[0037] Since the denitration combustion improver metal active metal component needs to be calcined at high temperature after being loaded, on the one hand, it is easy to cause local aggregation of the active metal, and on the other hand, it is easy to strengthen the chemical action and phase change between the active metal and the carrier silicon-aluminum metal, thereby reducing the action and utilization rate between the active metal and the phosphorus element. The introduction of the organic chelating agent in the present application can effectively chelate and redispersed the aggregated active metal, thereby dispersing the active center, weakening the action between the active metal and the carrier, and strengthening the chemical bond and oxidation, reduction and other synergistic effects between the active metal and the phosphorus element.

[0038] In addition, the organic chelating agent is sprayed under negative pressure, on the one hand, it can improve the utilization rate of the organic chelating agent and prevent local aggregation and excessive acidification from damaging the carrier skeleton; on the other hand, it can maximize the degree of the organic chelating agent fully dispersed and uniformly into the carrier pore and chemically chelated.

[0039] The application also provides the denitration combustion improver prepared by the preparation method, which has a specific surface area of 500-700 m 2 / g, an average particle size of 65-70 mu m, a particle size distribution of 40-140 mu m accounting for more than 80%, a pore volume of 0.50-0.80 mL / g, a sphericity of more than 0.95, and an attrition index of 0.5-0.8% / h.

[0040] Compared with the prior art, the application has the following beneficial effects:

[0041] (1) The application uses gamma-Al2O3 precursor and siloxane copolymer as raw materials, and obtains an amorphous pore structure silicon-aluminum compound carrier through spray forming, in-situ modification and pore forming, which has the characteristics of super large specific surface area and high pore volume, strong adsorption, and can provide sufficient catalytic oxidation and reduction reaction time and space for NO x and C / CO / NH3 and other reducing gases;

[0042] (2) The application uses phosphoric acid compounds to modify the silicon-aluminum compound carrier, which can form a-P-O-Al-O-Si-O-P- network stable structure with silicon and aluminum in the silicon-aluminum compound carrier, which can improve the wear resistance of the carrier, avoid the hydrothermal deactivation of the denitration combustion improver product, ensure that the denitration combustion improver is not easy to wear and break during use, prolong the service life, and increase the weak acid active points of the carrier, which is beneficial to the adsorption of part of the reducing gas during use, and improves the denitration combustion performance;

[0043] (3) The application optimizes the loading ratio and loading amount of noble metals and ordinary active metals, and simultaneously undergoes solvent chelation, which strengthens the interaction between different active metals, weakens the interaction between the active metals and the carrier, strengthens the chemical bond between the active metals and phosphorus elements, and optimizes the dispersion degree of the excess active metals, thereby maximizing the number of active centers;

[0044] (4) The application uses in-situ modification pore forming technology, different active metal combinations and redispersion technology, and the obtained denitration combustion improver has the effects of high-efficiency denitration and elimination of tail combustion, solves the environmental protection problem of flue gas NO x emission, can achieve zero ammonia injection to stop the SCR denitration module or zero ozone to stop the LoTO x denitration unit, or does not need to add an SCR and LoTO x process unit, solves the problems of ozone escape, ammonia escape, salt deposition, high total nitrogen in water, high energy consumption and high operation cost of the subsequent SCR, and does not produce salt-containing wastewater and secondary pollution problems when the denitration combustion improver is used;

[0045] (5) The denitrification combustion aid prepared by this invention can achieve high denitrification efficiency under low addition conditions. Only 1-2% of the additive is needed to remove NO from the regenerated flue gas. x Concentration blank value 400-1000 mg / m³ 3 Reduced to 30-90 mg / m 3 The scope meets national environmental protection standards and enterprise internal control process standards. At the same time, after adding this denitrification combustion aid, the addition of a single combustion aid product can be stopped, reducing denitrification costs, resulting in significant economic benefits, and ensuring safety and environmental protection. Attached Figure Description

[0046] Figure 1 Example 1: NO emission x Concentration change trend graph;

[0047] Figure 2 This is a graph showing the temperature variation trend of the rarefaction and density phases in the regenerator of Example 1.

[0048] Figure 3 Example 2: NO emission x Concentration and ammonia injection rate trend graph;

[0049] Figure 4 Example 3: NO emission x Concentration and ammonia injection rate trend graph;

[0050] Figure 5 This is a graph showing the temperature variation trend of the rarefaction and density phases in the regenerator of Example 3. Detailed Implementation

[0051] The present invention will be further described below with reference to the embodiments. Unless otherwise specified, the raw materials used in the embodiments are all commercially available conventional raw materials; unless otherwise specified, the process methods used in the embodiments are all conventional methods in the art.

[0052] Example 1

[0053] A denitrification combustion aid for the complete regeneration process of a catalytic cracking unit, comprising the following raw materials by weight percentage: 78% boehmite, 9% hydrophilic amino-modified polysiloxane copolymer (DY-N type, Shandong Dayi Chemical Co., Ltd.), 0.3% rhodium chlorohydrate, 0.7% silver nitrate, 1% EDTA-Zn, 1% isooctyl titanate, 2% zirconium acetate, 5% ammonium dihydrogen phosphate, and 3% tartaric acid.

[0054] The preparation method is as follows:

[0055] (1) Mix boehmite and hydrophilic amino-modified polysiloxane copolymer, add 55% by weight of chemical water, add hydrochloric acid to adjust the slurry pH to 2, age at 110°C for 12h, spray granulate at 220°C, dry at 270°C for 12h, and calcine at 850°C for 8h to obtain a silicon-aluminum compound, then immerse the silicon-aluminum compound in a 5wt.% sodium hydroxide solution, modify in situ at 120°C and 20kPa for 2h to obtain an in-situ modified silicon-aluminum compound, and control the temperature rising rate to be no more than 50°C / h during drying and calcination to prevent rapid dehydration and deformation of the particles and reduce sphericity;

[0056] (2) Dissolve ammonium dihydrogen phosphate in water to obtain a 10% aqueous solution, immerse the in-situ modified silicon-aluminum compound in the aqueous solution for 18h, then dry at 120°C for 2h, and calcine at 750°C for 8h to obtain a phosphorus-oxygen-silicon-aluminum compound;

[0057] (3) Dissolve chlororhodium acid, silver nitrate, EDTA-Zn, isooctyl titanate, and zirconium acetate in water to obtain a 5% aqueous solution, immerse the phosphorus-oxygen-silicon-aluminum compound in the aqueous solution for supersaturation impregnation for 24h, then dry at 140°C for 2h, and calcine at 800°C for 4h to obtain a denitration combustion-supporting agent semi-product;

[0058] (4) Place the denitration combustion-supporting agent semi-product in a high-efficiency spray double-cone, uniformly spray tartaric acid on the denitration combustion-supporting agent semi-product under negative pressure, rotate and stir for 2h, then dry at 160°C for 2h, and calcine at 650°C for 5h to obtain a denitration combustion-supporting agent for complete regeneration process of a catalytic cracking device.

[0059] The physicochemical indexes of the denitration combustion-supporting agent are: specific surface area 680m 2 / g, average particle size 65μm, 40-140μm particle size distribution ratio 85%, pore volume 0.78mL / g, sphericity 0.969, and abrasion index 0.79% / h.

[0060] The denitration combustion-supporting agent prepared in Example 1 was applied to a 2.0Mt / a heavy oil catalytic cracking device of a petrochemical company in Shandong, the device had a high-low parallel rapid bed plus turbulent bed counter-current structure, main wind was in series with two-stage oxygen-rich regeneration, the coke burning tank had a linear speed of 1.74m / s, the processing raw material was atmospheric residue, and the backfiring oil was fully backfired.

[0061] The device previously used a commercially available denitration combustion-supporting agent, and the physicochemical indexes were: specific surface area 260m 2 / g, average particle size 63 pm, 40-140 pm particle size distribution ratio 80%, pore volume 0.20 mL / g, non-spherical, abrasion index 2.89% / h. The filling amount is 250 kg / d, the flue gas NO x The concentration is reduced to 176 mg / m 3 The flue gas NO 3 The concentration is maintained at 150-200 mg / m x The edge is kept, the intermittent ammonia injection of the SCR denitration ammonia injection module prevents over-standard, the dilute phase temperature of the regenerator is 708-712 DEG C, which causes the inlet temperature of the flue gas turbine to reach 689 DEG C, which exceeds the design index of 685 DEG C.

[0062] The commercial denitration combustion improver is a denitration combustion improver prepared by loading active metals on a carrier of gamma-Al2O3. Compared with the denitration combustion improver prepared in Example 1, the specific surface area, the pore volume, the sphericity and the abrasion index are large, small, high and small, respectively. Therefore, the denitration combustion improver of the application can achieve better denitration combustion effect under the condition of a lower usage amount. The increase of the specific surface area and the pore volume means that more reduction components and NO x The catalyst can obtain more residence, contact and reaction time, and the denitration combustion effect can be greatly improved. The increase of the abrasion index and the improvement of the sphericity mean that the denitration combustion improver has a longer life cycle in the fluidization system, and the mutual abrasion and consumption with the main catalyst are reduced to the maximum extent. After the phosphorus modification, the performance of the denitration combustion improver in the thermal shock and hydrothermal deactivation of the system is further improved, and the synergistic effect of prolonging the life cycle is achieved.

[0063] In order to further reduce the flue gas NO x The concentration of the flue gas NO 3 is reduced to 100 mg / m 3 or less, so as to achieve the purpose of completely stopping the SCR denitration ammonia injection module and reducing the degree of tail combustion and the dilute phase temperature. The denitration combustion improver of Example 1 is used in the device on September 10, 2020. Before the trial, the device is blank calibrated from September 5 to 9, 2020. The denitration combustion improver of Example 1 is added on September 10, 2020. The device is calibrated for 5 days from October 9 to 13, 2020.

[0064] The implementation scheme is as follows.

[0065] (1) The system inventory is established according to the system inventory of 1.5% (mass fraction), and the daily filling amount is 150 kg per day;

[0066] (2) The rapid filling stage: from September 10, 2020 to October 8, 2020, the denitration combustion improver is continuously added for 21 days, so that the denitration combustion improver is quickly accumulated to 1.5% of the system inventory, and then the daily filling stage is entered;

[0067] (3) Daily injection stage: 150 kg of denitration combustion improver was injected every day, and the effect calibration was carried out for 5 days from October 9th to 13th.

[0068] The raw material properties and operating parameters before and after the injection of denitration combustion improver are shown in Table 3.

[0069] Table 1

[0070] Parameter name Blank calibration Trial period calibration Processing capacity, t / h 225 226 Feed oil composition Normal residue Normal residue Carbon residue, % 5.2 5.3 Density (20°C), kg / m 3 ]] 911 909 S, % (m / m) 0.44 0.43 N, mg / kg 2160 2155 First dense phase temperature, °C 685 689 Second dilute phase temperature, °C 710 705 Second dense phase temperature, °C 695 700 Flue gas inlet temperature, °C 689 683 Repetitive air volume, Nm 3 / h]] 287000 288000 Excess oxygen content, % 1.9 2.0 Exhaust gas NO x Concentration, mg / m 3 ]]> 150-200 70-90

[0071] The application effects are as follows:

[0072] Outlet NO x The concentration change trend is shown in Figure 1 From Figure 1 It can be clearly seen that with the addition of denitration combustion improver and the increase of system inventory, the mass concentration of NO x at the outlet of the flue gas denitrification tower decreased from 176 mg / m 3 in the blank period to 74.4 mg / m 3 , a decrease of 101.6 mg / m 3 , a removal rate of 57.7%, meeting the requirement of NO x concentration <100 mg / m 3 of the outlet flue gas, and completely meeting the process requirement of stopping the SCR denitration module.

[0073] The temperature change trend of the regenerator dilute-dense phase is shown in Figure 2 From Figure 2 It can be clearly seen that with the addition of denitration combustion improver and the increase of system inventory, the temperature of the dense phase bed of the regenerator gradually increased from 695℃ to 699℃, and the temperature of the dilute phase gradually decreased to below 705℃, the temperature difference between the dilute and dense phases became smaller, indicating that the combustion-supporting components in the denitration combustion improver fully played a combustion-supporting role in the bed, and the dense phase bed of the regenerator absorbed the heat of CO combustion, resulting in an increase in the temperature of the dense phase bed and a decrease in the temperature of the dilute phase.

[0074] In addition, during the calibration period, there was no adverse effect on product distribution, product properties, main catalyst fluidization, and device operation.

[0075] Example 2

[0076] A denitration combustion improver for a complete regeneration process of a catalytic cracking unit, the weight percentage of the raw materials is as follows: pseudo-boehmite 62%, polyether modified siloxane copolymer (DY-ET type, Shandong Dayi Chemical Co., Ltd.) 15%, chloropalladic acid 2.9%, chlororhodic acid 0.1%, zirconium acetate 5%, neodymium acetate 1%, lanthanum cerium oxalate 4%, phosphoric acid 6%, and citric acid 4%.

[0077] The preparation method is as follows:

[0078] (1) Mix pseudo-boehmite and polyether-modified siloxane copolymer, add 35% by weight of chemical water, add nitric acid to adjust the slurry pH to 3, age at 130°C for 14h, spray granulate at 230°C, then dry at 260°C for 16h, and calcine at 820°C for 12h to obtain a silicon-aluminum compound, then immerse the silicon-aluminum compound in a 7wt.% sodium hydroxide solution, modify in situ at 130°C and 30kPa for 3h to obtain an in-situ modified silicon-aluminum compound, and control the temperature rise rate to be no greater than 50°C / h during drying and calcining to prevent rapid dehydration and deformation of the particles and reduce sphericity;

[0079] (2) Dissolve phosphoric acid in water to obtain a 15% mass concentration aqueous solution, immerse the in-situ modified silicon-aluminum compound in the aqueous solution for 20h, then dry at 170°C for 3h, and calcine at 820°C for 6h to obtain a phosphorus-oxygen-silicon-aluminum compound;

[0080] (3) Dissolve chloropalladic acid, chlororhodic acid, zirconium acetate, neodymium acetate, and lanthanum cerium oxalate in water to obtain a 6% total mass concentration aqueous solution, immerse the phosphorus-oxygen-silicon-aluminum compound in the aqueous solution for supersaturation impregnation for 30h, then dry at 160°C for 3h, and calcine at 750°C for 5h to obtain a denitration combustion-supporting agent semi-finished product;

[0081] (4) Place the denitration combustion-supporting agent semi-finished product in a negative pressure high-efficiency spray double cone, uniformly spray citric acid on the denitration combustion-supporting agent semi-finished product under negative pressure, rotate and stir for 3h, then dry at 180°C for 3h, and calcine at 680°C for 6h to obtain a denitration combustion-supporting agent for a complete regeneration process of a catalytic cracking device.

[0082] The physicochemical indexes of the denitration combustion-supporting agent are: specific surface area 600m 2 / g, average particle size 67μm, 40-140μm particle size distribution ratio 84%, pore volume 0.7mL / g, sphericity 0.96, and abrasion index 0.71% / h.

[0083] The denitration combustion-supporting agent prepared in Example 2 was applied to a 3.0Mt / a heavy oil catalytic cracking device of a certain petrochemical company in Zhejiang. The device adopts a high-low parallel two-stage complete regeneration process structure, and the flue gas adopts an SCR denitration+EDV wet desulfurization combined process to achieve environmental protection emission standards. However, in the actual production operation process, the NO x mass concentration in the regeneration flue gas was relatively high, at 450-500mg / m 3 , resulting in a large amount of ammonia injection, with an hourly ammonia consumption of 90-100m 3 , and serious salt deposition at the outlet of the surplus pot and blue smoke plume at the outlet of the smoke desulfurization, which seriously affected the safe operation of the catalytic device.

[0084] In order to reduce NO in regenerated flue gas from the source x The concentration was reduced, the amount of ammonia injected was decreased, the SCR operating cycle was extended, and ultra-clean emissions were achieved. The device was tested on April 8, 2022, using the denitrification combustion aid from Example 2. The results met the process requirements, effectively solved the safety hazards of long-term operation of the device, and the economic benefits were significant.

[0085] The implementation plan is as follows:

[0086] The denitrification combustion aid was established over a period of 60 days. It was intermittently added to the regenerator daily using the original CO combustion aid filling system. Simultaneously, the denitrification combustion aid from Example 2 was added, followed by the discontinuation of the CO combustion aid (Pt type). The goal was to achieve a denitrification combustion aid concentration of 1.5% of the total system concentration (mass fraction), with a daily addition rate of 125 kg / day to maintain the denitrification combustion aid concentration in the regeneration system. Specifically, from April 8th to June 8th, 2022, was the rapid accumulation period, with additions three times daily at a rate of 150-600 kg / day, reaching 1.5% concentration by June 8th. After June 8th, 2022, the period became the routine addition period, with additions three times daily at a rate of 125 kg / day.

[0087] The feedstock for the unit is secondary hydrogenated, that is, the wax oil that has undergone slurry bed hydrocracking reaction is hydrorefined and then fed into the catalytic cracking unit. The properties of the feedstock and operating parameters before and after adding the denitrification combustion aid are shown in Table 2.

[0088] Table 2

[0089] Item Blank calibration Trial period calibration Density, 20°C, kg m -3 ]] 908 913 Viscosity, 100°C, mm 2 ·s -1 ]]> 4.86 4.80 Throughput, t·h -1 ]]> 350 220-350 Riser outlet temperature, °C 513 513 First dense phase bed temperature, °C 685 667-685 Second dilute phase temperature, °C 686-688 678-688 Second dense phase bed temperature, °C 694 680-694 Regenerator constant pressure, MPa 0.26 0.25-0.27 Coking drum capacity, t 80 80 Regenerator capacity, t 120 130 Heat extracted outside the regenerator, t.h -1 ]]> 90 70-90 Main air quantity, Nm 3 • h -1 ]]> 288000 220000-288000 Excess oxygen O2, % 2.0 2.0-4.6

[0090] The application results are as follows:

[0091] NO external discharge x The trends of concentration and ammonia injection rate are as follows: Figure 3 As shown, by Figure 3 It is evident that with the addition of denitrification combustion improver and the increase in system stock, when the denitrification combustion improver accounts for 1.5% of the mass of the regeneration system, the NO in the SCR inlet regeneration flue gas decreases. x The mean concentration blank was 450 mg / m³ 3 The hourly average decreased and stabilized at an average of 80 mg / m³. 3 The denitrification rate reached 82.2%, while the SCR NH3 injection rate was reduced from 95m³. 3 / h decreased to 0, and the exhaust gas met the NO standard. x Concentration <100mg / m 3 The performance indicators must fully meet the process requirements for shutting down the SCR denitrification module.

[0092] The temperature change of the dilute phase of the regenerator is as follows: after the denitration combustion improver is added on April 8, 2022, and the Pt combustion improver added in the early stage is completely stopped, the temperature of the dilute phase of the regenerator is relatively stable and does not rise. As can be seen from Table 2, the highest temperature is the same as that of the blank period, but the temperature of the dilute phase decreases to 678℃ during the addition of the denitration combustion improver, which is better than the effect of adding pure denitration combustion improver.

[0093] In addition, there is no adverse effect on product distribution, product properties, main catalyst fluidization, and device operation during calibration.

[0094] Example 3

[0095] A denitration combustion improver for a complete regeneration process of a catalytic cracking unit, the weight percentage of the raw materials is as follows: pseudo-boehmite 70%, polyether modified siloxane copolymer (DY-ET type, Shandong Dayi Chemical Co., Ltd.) 14%, chloropalladic acid 1%, silver nitrate 1%, EDTA-Zn 0.5%, isooctyl titanate 1.5%, antimony acetate 2%, lanthanum cerium oxalate 4%, phosphoric acid 4%, and tricarballylic acid 2%.

[0096] The preparation method is as follows:

[0097] (1) Mix the pseudo-boehmite and the polyether modified siloxane copolymer, add 25% of the weight of chemical water, and add hydrochloric acid to adjust the pH value of the slurry to 4, age at a temperature of 140℃ for 16h, spray granulation at a temperature of 250℃, obtain spherical particles, then dry at a temperature of 280℃ for 10h, and calcine at a temperature of 900℃ for 6h to obtain a silicon-aluminum compound, then immerse the silicon-aluminum compound in a 10wt.% sodium hydroxide solution, modify in situ at a temperature of 140℃ and a pressure of 50kPa for 4h to obtain an in-situ modified silicon-aluminum compound, and control the temperature rising rate to be not greater than 50℃ / h during drying and calcination to prevent the particles from dehydrating too fast and deforming to reduce the sphericity;

[0098] (2) Dissolve the phosphoric acid in water to obtain a 20% aqueous solution, immerse the in-situ modified silicon-aluminum compound in the aqueous solution for 24h, then dry at a temperature of 200℃ for 4h, and calcine at a temperature of 900℃ for 5h to obtain a phosphorus-oxygen-silicon-aluminum compound;

[0099] (3) Dissolve the chloropalladic acid, silver nitrate, EDTA-Zn, isooctyl titanate, antimony acetate, and lanthanum cerium oxalate in water to obtain a 10% aqueous solution, immerse the phosphorus-oxygen-silicon-aluminum compound in the aqueous solution for supersaturation impregnation for 36h, then dry at a temperature of 180℃ for 2h, and calcine at a temperature of 780℃ for 4h to obtain a denitration combustion improver semi-finished product;

[0100] (4) The denitration combustion improver semi-finished product is placed in a negative pressure high-efficiency spray double cone, tartrate is uniformly sprayed in the denitration combustion improver semi-finished product under negative pressure, rotary stirring is performed for 3 h, then drying is performed at 200 ℃ for 2 h, and calcination is performed at 700 ℃ for 5 h, to obtain the denitration combustion improver for the complete regeneration process of a catalytic cracking device.

[0101] The physical and chemical indexes of the denitration combustion improver are as follows: a specific surface area of 520 m 2 / g, an average particle size of 69 μm, a particle size distribution of 40-140 μm accounting for 82%, a pore volume of 0.56 mL / g, a sphericity of 0.952, and an abrasion index of 0.51% / h.

[0102] The denitration combustion improver prepared in Example 3 is applied to a 1.8 Mt / a heavy oil catalytic cracking device of a certain petrochemical company in Shaanxi. The device adopts a heavy oil catalytic cracking MIP technology, and the reverse and regeneration sections are high and low parallel fast bed main wind series two-stage complete regeneration process technology. The design upper limit of the coke storage capacity is 60 t, the linear speed is 1.84 m / s, the design operating temperature is 640-690 ℃, the regeneration device design storage capacity is 110-200 t, the linear speed is 0.65 m / s, and the design operating temperature is 680-720 ℃. The design raw material carbon residue mass fraction is 5-6%.

[0103] At present, the device processes atmospheric residue oil mixed with part of oil slurry, and the recycled oil is not discharged. The SCR inlet NO x x average is 600 mg / m 3 , the average ammonia injection amount is 65 m 3 / h, and at the same time, the tail combustion is serious, and the CO combustion improver (Pt type) is added to control the temperature of the west smoke phase. The flue gas purification system adopts the selective catalytic reduction (SCR) flue gas denitration process and the EDV5000 wet flue gas desulfurization washing process of BELCO company. Since the SCR denitration unit was put into use in 2015, the SCR unit denitration catalyst has appeared aging, failure, large ammonia injection amount, serious salt deposition at the outlet of the remaining pot, and the like, resulting in continuous decrease of the denitration rate. The denitration rate is reduced from 95% at the beginning to 30%.

[0104] In order to make the catalytic cracking device regeneration flue gas meet the local environmental protection index requirement NO x x concentration <100 mg / m 3 , and realize the stop of ammonia injection of the SCR denitration unit to reduce the safety risk, the stop of the addition of the CO combustion improver (Pt type), the reduction of the replacement frequency of the SCR denitration catalyst (the original replacement is once every 4 years, and the cost of each replacement is about 8 million yuan), the extension of the use cycle, and the improvement of the economic operation benefit of the device, the denitration combustion improver of Example 3 is started to be tested on July 28, 2020.

[0105] The implementation scheme is as follows:

[0106] The CO combustion improver was intermittently added to the regenerator daily using the catalytic cracking unit's CO combustion improver injection system. The trial period was divided into two phases, with the goal of achieving a CO combustion improver content of 1.5% of the total system content (mass fraction). The specific plan was as follows: July 28 to September 10, 2020: rapid injection to build up the stockpile, with injections three times daily at a rate of 200-400 kg / day; CO combustion improver (Pt) injection was discontinued on August 1; and the CO combustion improver content reached 1.5% by September 24. The routine injection period was from September 25 to October 5, 2022, with injections three times daily at a rate of 100 kg / day.

[0107] The properties of raw materials and operating parameters before and after adding the denitrification combustion aid are shown in Table 3.

[0108] Table 3

[0109]

[0110]

[0111] The application results are as follows:

[0112] NO external discharge x The trends of concentration and ammonia injection rate are as follows: Figure 4 As shown, by Figure 4 It is evident that with the addition of denitrification combustion improver and the increase in system stock, when the denitrification combustion improver accounts for 1.5% of the mass of the regeneration system, the NO in the SCR inlet regeneration flue gas decreases. x The mean concentration blank was 600 mg / m³ 3 The hourly average decreased and stabilized at an average of 65 mg / m³. 3 The denitrification rate reached 89%, and the SCR NH3 injection rate increased from the blank average of 65m³. 3 / h decreased to 0, and the exhaust gas met the NO standard. x Concentration <100mg / m 3 The performance indicators must fully meet the process requirements for shutting down the SCR denitrification module.

[0113] The temperature variation trend of the rarefaction phase in the regenerator is as follows: Figure 5 As shown, by Figure 5 It can be seen that after the addition of denitrification combustion aid on July 28, when the proportion of denitrification combustion aid added to the system reaches a stable period of 1.5% of the total stock, the dilute phase temperature of the regenerator drops from the average of 712℃ during the blank period to 701℃, and the temperature difference between the dilute and dense phases drops from the average of 18℃ during the blank period to 8℃, indicating a significant combustion aid effect.

[0114] Furthermore, the use of denitrification aids did not adversely affect the properties of the catalyst, normal fluidization, the properties of the product from the unit, or the product yield.

Claims

1. A process for the preparation of a deNOx combustion improver for a full regeneration process of a catalytic cracking unit, characterized in that: The method comprises the following steps: (1) mixing a γ-Al2O3 precursor and a siloxane copolymer, adding chemical water and a sol agent, stirring to obtain a slurry, aging, spray granulation to obtain spherical particles, drying at 220-280°C for 10-20h, calcining at 700-900°C for 6-16h to obtain a silicon-aluminum compound, and then immersing the silicon-aluminum compound in a sodium hydroxide solution, in-situ modification at 120-140°C and 20-50kPa for 2-4h to obtain an in-situ modified silicon-aluminum compound; (2) immersing the in-situ modified silicon-aluminum compound in an aqueous solution of a phosphoric acid compound for impregnation, drying at 100-200°C for 2-4h, and calcining at 700-900°C for 4-8h to obtain a phosphorus-oxygen-silicon-aluminum compound; (3) immersing the phosphorus-oxygen-silicon-aluminum compound in an aqueous solution of a noble metal inorganic compound and a metal organic compound for impregnation, drying at 140-180°C for 2-4h, and calcining at 700-800°C for 4-6h to obtain a denitration combustion-supporting agent semi-finished product; (4) uniformly spraying an organic chelating agent on the denitration combustion-supporting agent semi-finished product under negative pressure, stirring, drying at 160-200°C for 2-4h, and calcining at 650-700°C for 5-7h to obtain a denitration combustion-supporting agent for complete regeneration process of a catalytic cracking device.

2. The process for the preparation of a deNOx combustion improver for the total regeneration process of catalytic cracking units according to claim 1, characterized in that: The weight percentage of the raw materials is as follows: the γ-Al2O3 precursor 62-78%, the siloxane copolymer 9-15%, the noble metal inorganic compound 1-3%, the metal organic compound 4-10%, the phosphoric acid compound 4-6%, and the organic chelating agent 2-4%.

3. The process for the preparation of a deNOx combustion improver for the total regeneration process of catalytic cracking units according to claim 1, characterized in that: In step (1), the γ-Al2O3 precursor is at least one of pseudo-boehmite and boehmite; and the siloxane copolymer is at least one of a polyether-modified siloxane copolymer and a hydrophilic amino-modified polysiloxane copolymer.

4. The process for the preparation of a deNOx combustion improver for the total regeneration process of catalytic cracking units according to claim 1, characterized in that: In step (1), the molar ratio of aluminum to silicon in the slurry is (20-200):1; the amount of water added is 25-55% of the total mass of the γ-Al2O3 precursor and the siloxane copolymer; and the sol agent is a hydrochloric acid or nitric acid solution, which is added to the slurry to a pH value of 2-4.

5. The method of claim 1, wherein the method is characterized by: In step (1), the concentration of the sodium hydroxide solution is 5-10wt.%.

6. The process for the preparation of a deNOx combustion improver for the total regeneration process of catalytic cracking units according to claim 1, characterized in that: In step (1), the aging temperature is 90-140°C, and the aging time is 10-16h; and the spray granulation temperature is 200-250°C.

7. The process for the preparation of a deNOx combustion improver for the total regeneration process of catalytic cracking units according to claim 1, characterized by the fact that: In step (2), the phosphoric acid compound is at least one of phosphoric acid and ammonium dihydrogen phosphate; in the aqueous solution of the phosphoric acid compound, the mass concentration of the phosphoric acid compound is 10-20%; and the impregnation time is 12-24h.

8. The process for the preparation of a deNOx combustion improver for the total regeneration process of catalytic cracking units according to claim 1, characterized by the fact that: In step (3), the noble metal inorganic compound is at least one of chloropalladic acid, chlororhodic acid, and silver nitrate; the metal organic compound is at least two of EDTA-Zn, isooctyl titanate, antimony acetate, zirconium acetate, cobalt polyphthalocyanine, neodymium acetate, and lanthanum cerium oxalate; in the aqueous solution of the noble metal inorganic compound and the metal organic compound, the total mass concentration of the noble metal inorganic compound and the metal organic compound is 3-10%; the impregnation time is 24-36h, and the impregnation is performed by over-saturation.

9. The process for the preparation of a deNOx combustion improver for the total regeneration process of catalytic cracking units according to claim 1, characterized in that: In step (4), the organic chelating agent is at least one of citric acid, tricarballylic acid, and tartaric acid.

10. A deNOx combustion improver for a fluid catalytic cracking unit full regeneration process, produced by the production process according to any one of claims 1 to 9, characterized by: a specific surface area of 500-700 m 2 / g, an average particle diameter of 65-70 μm, a particle diameter distribution of 40-140 μm accounting for more than 80%, a pore volume of 0.50-0.80 mL / g, a sphericity of more than 0.95, and an attrition index of 0.5-0.8% / h.

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