Methods for suppressing CO and CO2 generation and reducing amine foaming in jet fuel hydrogenation processes

Abstract

The present application relates to the field of marine diesel fuel hydrogenation refining, and particularly relates to a comprehensive control method for inhibiting CO and CO2 generation in circulating hydrogen, reducing foaming of amine liquid desulfurization system and improving liquid yield, comprising the following steps: step one, modification and loading of catalyst, wherein the modified hydrogenation catalyst comprises a carrier, an active metal component and a hydrophobic additive; step two, online addition of CO and CO2 generation inhibitor during the reaction, wherein the inhibitor is used for preferentially adsorbing on the decarbonylation / decarboxylation active site of the catalyst; step three, anti-foaming operation of the amine liquid desulfurization system, wherein the hydrogenation product is subjected to desulfurization by using a modified MDEA desulfurization solution, and the modified MDEA desulfurization solution comprises an anti-foaming additive; and step four, synergistic control of waste hydrogen discharge and circulating hydrogen purity, wherein the addition amount of the inhibitor is adjusted in real time according to the CO and CO2 concentration in the circulating hydrogen, and the present application has the following beneficial effects: the CO and CO2 concentration in the reaction of the existing marine diesel fuel hydrogenation device and the waste hydrogen discharge amount are reduced.

Description

Technical Field

[0001] This invention relates to the field of hydrorefining and hydromodification of aviation kerosene, and particularly to a comprehensive control method for suppressing the generation of CO and CO2 in circulating hydrogen, while reducing foaming in the amine desulfurization system and improving liquid yield. Background Technology

[0002] Aviation kerosene hydrotreating units commonly face a significant increase in CO and CO2 concentrations in the circulating hydrogen during the later stages of reaction operation. The main sources of CO and CO2 include the decarbonylation / decarboxylation reactions of oxygen-containing compounds such as carboxylic acids, phenols, and alcohols in the feedstock. As the catalyst ages and the reaction temperature increases, the rate of CO and CO2 generation accelerates, forcing companies to release large amounts of waste hydrogen to maintain the purity of the circulating hydrogen, resulting in hydrogen waste and increased costs.

[0003] Meanwhile, the high concentration of CO2 in the circulating hydrogen enters the amine desulfurization system. On the one hand, it reacts with the NH3 generated during hydrogenation to form solid or colloidal substances such as ammonium carbonate. On the other hand, it directly alters the ion balance of the amine liquid system, inducing severe foaming problems. Foaming leads to decreased desulfurization efficiency, amine liquid loss, and carries liquid phase into the circulating hydrogen compressor, increasing energy consumption and shortening catalyst life.

[0004] To address the aforementioned issues, existing technologies often take a single approach, such as replacing the catalyst, adding defoamers, or installing membrane separation devices, but fail to systematically resolve the chain reaction of "CO and CO2 generation - waste hydrogen emission - amine foaming - yield reduction". Summary of the Invention

[0005] The purpose of this invention is to provide a method for suppressing the generation of CO and CO2 and reducing amine foaming in the aviation kerosene hydrogenation process, so as to solve the problems of deterioration of circulating hydrogen quality, high operating cost and poor stability at the end of the reaction in existing aviation kerosene hydrogenation units.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a method for inhibiting the generation of CO and CO2 and reducing amine foaming in a jet fuel hydrogenation process, comprising the following steps:

[0007] Step 1, catalyst modification and loading: A modified hydrogenation catalyst is loaded into the hydrogenation reactor. The modified hydrogenation catalyst includes a support, an active metal component, and a hydrophobic promoter. The hydrophobic promoter is used to inhibit the adsorption of water on the catalyst surface, thereby inhibiting the water-gas shift reaction and the reverse water-gas shift reaction.

[0008] Step 2, online addition of CO and CO2 generation inhibitors during the reaction: During the hydrogenation reaction, CO and CO2 generation inhibitors are added online to the reaction system. The inhibitors are used to preferentially adsorb onto the decarbonylation / decarboxylation active sites of the catalyst to reduce the selectivity of the decarbonylation / decarboxylation reaction of oxygen-containing compounds.

[0009] Step 3, anti-foaming operation of the amine desulfurization system: The hydrogenation products are desulfurized using a modified MDEA desulfurization solution, which contains an anti-foaming additive.

[0010] Step 4, Coordinated control of waste hydrogen emissions and circulating hydrogen purity: Adjust the amount of inhibitor added in real time according to the total concentration of CO and CO2 in the circulating hydrogen.

[0011] Preferably, the hydrophobic additive is CeO2, and its mass is 5% of the mass of the carrier.

[0012] Preferably, the hydrophobic additive is SO4. 2- The combination of modified TiO2 and In2O3, in which SO4 2- The mass of modified TiO2 is 3% of the mass of the support, and the mass of In2O3 is 2% of the mass of the support.

[0013] Preferably, the hydrophobic additive is a combination of CeO2 and ZrO2, wherein the mass of CeO2 is 3% of the mass of the carrier and the mass of ZrO2 is 2% of the mass of the carrier.

[0014] Preferably, the inhibitor is a compound of maleic anhydride, dimethylformamide and acetylacetonate iron in a mass ratio of 10:5:1, and the amount added is 300-500 ppm of the raw oil mass.

[0015] Preferably, the anti-foaming agent is a composite of polyether-modified polysiloxane and nano-silica, wherein the mass ratio of polyether-modified polysiloxane to nano-silica is 3:1, and the mass fraction of the anti-foaming additive in the modified MDEA desulfurization solution is 1.2%.

[0016] Preferably, in step three, the hydrogenation reaction temperature is 320–350°C, the reaction pressure is 6.0–8.0 MPa, the hydrogen-to-oil volume ratio is 380–450:1, and the liquid hourly space velocity is 1.2–1.8 h⁻¹. -1 .

[0017] Preferably, in step four, when the total concentration of CO and CO2 exceeds 50 μL / L, the reaction temperature is reduced by 5–15 °C and / or the hydrogen-to-oil ratio is increased by 10–30%; when the total concentration of CO and CO2 is higher than 80 μL / L, the amount of inhibitor injected is increased to 200–1500 ppm; when the total concentration of CO and CO2 drops below 30 μL / L, the amount of inhibitor injected is reduced to 50–200 ppm.

[0018] Preferably, in step three, the operating temperature of the desulfurization system is 42°C, and the amine liquid circulation volume is 1.2 times the theoretical absorption volume; when the foaming height of the amine liquid exceeds 15 mm, polydimethylsiloxane emulsion is injected online as a defoamer, and the injection volume is 30 ppm of the amine liquid circulation volume.

[0019] Preferably, the amount of waste hydrogen emissions should be kept below 8% of the total amount of recycled hydrogen.

[0020] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. By reducing the contribution of the reaction to carbon oxides through hydrophobic modification of the catalyst, and by inhibiting decarbonylation and decarboxylation reactions through in-situ chemical inhibitors, the total concentration of CO and CO2 generated can be reduced by up to 68% at the source;

[0022] 2. Waste hydrogen emissions are reduced by more than 60% compared to conventional operation, hydrogen utilization is improved, and the overall energy consumption of the unit is reduced;

[0023] 3. At the end of the reaction, the total concentration of CO and CO2 and the amount of waste hydrogen emitted are much lower than those of conventional technologies;

[0024] 4. By using a modified MDEA formula and online defoaming linkage, the foaming height of the amine liquid is controlled below 10mm, the defoaming time is ≤3 seconds, and the desulfurization efficiency is maintained above 98%, effectively alleviating the foaming problem of amine liquid;

[0025] 5. Due to the increased purity of circulating hydrogen and the rise in H2 partial pressure, the hydrogenation reaction depth is improved, and the yield of liquid products from jet fuel is increased by 1.5 percentage points compared with the existing process, thus improving the liquid yield. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the device in this invention.

[0027] In the diagram, 1. Hydrogen-refined feedstock tank; 2. Feedstock filter; 3. Hydrogen-refined feedstock pump; 4. Electric heater; 5. Reactor; 6. Condenser; 7. MDEA solution feed tank; 8. Feed pump; 9. Bubbling tower. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings.

[0029] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

[0030] The apparatus used in this invention is as follows Figure 1As shown, it includes a hydrorefined feedstock tank 1, a feedstock filter 2, a hydrorefined feedstock pump 3, an electric heater 4, a reactor 5, a condenser 6, an MDEA solution feed tank 7, a feed pump 8, and a bubble column 9.

[0031] The feedstock oil is transported from the hydrorefining feedstock oil tank 1, through the feedstock oil filter 2, and into the electric heater 4 by the hydrogen feedstock oil feed pump 3; hydrogen gas is also transported to the electric heater 4 via pipeline. The feedstock oil and hydrogen gas then undergo a hydrogenation reaction.

[0032] The reacted material enters the bubble column 9 through the condenser 6; the MDEA desulfurization solution enters the bubble column 9 from the MDEA solution feed tank 7 under the conveying of the feed pump 8 to carry out the amine desulfurization reaction.

[0033] Example 1:

[0034] The purpose of this embodiment is to verify the effectiveness of the basic formula.

[0035] Small-scale experiment:

[0036] The reaction was carried out on a fixed-bed micro hydrogenation reactor with a catalyst loading of 100 mL.

[0037] The raw material was the actual feedstock oil of a refinery's aviation kerosene hydrogenation unit, which contained 820 ppm sulfur, 118 ppm nitrogen, 0.36% oxygen, and 0.25 mg KOH / g acid value.

[0038] Step 1: Modification and loading of the catalyst.

[0039] A modified hydrogenation catalyst is loaded into the hydrogenation reactor. The modified hydrogenation catalyst includes: a support, an active metal component, and a hydrophobic promoter.

[0040] The carrier is generally selected from one of alumina, silicon oxide, and titanium oxide, or a composite oxide thereof. In this embodiment, NiMo / γ-Al2O3 is selected.

[0041] The active metal component is generally selected from Group VIB metals such as Mo and W, or Group VIII metals such as Co and Ni. In this embodiment, CoMoO4 is selected.

[0042] The hydrophobic additive is CeO2, with a mass of 5 wt% of the carrier. The hydrophobic additive is prepared by an equal-volume impregnation method and calcined at 550℃ for 4 hours. It inhibits the adsorption of water on the catalyst surface, thereby inhibiting the water-gas shift reaction and the reverse water-gas shift reaction.

[0043] Step two: During the reaction process, CO and CO2 generation inhibitors are added online.

[0044] An inhibitor, a mixture of maleic anhydride, dimethylformamide, and ferric acetylacetonate in a mass ratio of 10:5:1, is added at an amount of 300 ppm of the feedstock oil mass via a metering pump into the reactor inlet line. This inhibitor preferentially adsorbs onto the decarbonylation and decarboxylation active sites of the catalyst, reducing the selectivity of decarbonylation and decarboxylation reactions of oxygen-containing compounds and decreasing the generation of CO and CO2.

[0045] Step 3: Optimize the hydrogenation reaction process conditions

[0046] The hydrogenation reaction temperature was controlled at 320℃, the reaction pressure at 6.0 MPa, the hydrogen-to-oil volume ratio at 400:1, and the liquid hourly space velocity at 1.5 h⁻¹. -1 In the later stages of the reaction cycle, the reaction temperature and hydrogen-to-oil ratio are dynamically adjusted in real time according to the concentrations of CO and CO2 in the circulating hydrogen. When the total concentration of CO and CO2 exceeds 50 μL / L, the reaction temperature is reduced by 5-15℃ and / or the hydrogen-to-oil ratio is increased by 10%-30%.

[0047] Step 4: Anti-foaming operation of the amine desulfurization system

[0048] A modified MDEA desulfurization solution is used, wherein the modified MDEA desulfurization solution comprises:

[0049] The desulfurization system comprises 25% N-methyldiethanolamine and an anti-foaming additive by mass, with the remainder being water. The anti-foaming additive is a polyether-modified polysiloxane and nano-SiO2 composite at a mass ratio of 3:1, and the addition amount of the anti-foaming additive is 1.2%. The operating temperature of the desulfurization system is 42℃, and the amine liquid circulation rate is 1.2 times the theoretical absorption rate. When the foaming height of the amine liquid exceeds 15mm, an antifoaming agent, which is a polydimethylsiloxane emulsion, is injected online at a rate of 30ppm of the amine liquid circulation rate.

[0050] Step 5: Coordinated control of waste hydrogen emissions and recycled hydrogen purity

[0051] When the total concentration of CO and CO2 in the circulating hydrogen exceeds 80 μL / L, the inhibitor injection rate is automatically increased to 200-1500 ppm, and the bypass purification of the amine regeneration tower is activated simultaneously. When the total concentration of CO and CO2 drops below 30 μL / L, the inhibitor injection rate is reduced to 50-200 ppm. The waste hydrogen emission is maintained at no more than 8% of the total circulating hydrogen.

[0052] The results after 200 hours of continuous operation are shown in the table below:

[0053]

[0054] Example 2:

[0055] The purpose of this embodiment is to verify the effectiveness of the present invention under different hydrophobic additives and higher temperature conditions.

[0056] Experimental conditions:

[0057] It is basically the same as Example 1, except that:

[0058] (1) The hydrophobic additive for the catalyst was changed to 3wt% SO4. 2- -TiO2+ 2wt% In2O3, introduced by equal volume impregnation method;

[0059] (2) The reaction temperature was increased to 350℃ to simulate the high-temperature conditions at the end of the reaction;

[0060] (3) The amount of inhibitor added in step two is increased to 500 ppm;

[0061] (4) The reaction pressure was maintained at 6.0 MPa, the hydrogen-to-oil ratio at 450:1, and the liquid hourly space velocity at 1.2 h⁻¹. -1 It runs for 200 hours.

[0062] result:

[0063]

[0064] Characterization results: TG-DTA analysis of the discharged catalyst showed that the coking amount of the catalyst in Example 2 was 3.8 wt%, while the coking amount in the control experiment was 6.2 wt%, indicating that the method of the present invention reduces coking formation and extends catalyst life.

[0065] Example 3:

[0066] The purpose of this embodiment is to verify the effectiveness of the present invention under low inhibitor addition and optimized amine liquid formulation.

[0067] Experimental conditions:

[0068] It is basically the same as Example 1, except that:

[0069] (1) The amount of inhibitor added was reduced to 150 ppm;

[0070] (2) The anti-foaming additive in the amine liquid formulation was replaced with polyether-modified polysiloxane used alone, without nano-SiO2, and the addition amount was 0.8%;

[0071] (3) The operating temperature of the amine solution was increased to 55℃ to simulate summer working conditions;

[0072] (4) Reaction pressure 6.2 MPa, hydrogen-to-oil ratio 380:1, space velocity 1.8 h⁻¹ -1 It runs for 200 hours.

[0073] result:

[0074]

[0075] Conclusion: Even with the inhibitor dosage reduced to 150 ppm, a significant inhibitory effect was still achieved, with the total concentrations of CO and CO2 decreasing from 101 μL / L to 53 μL / L, indicating that the inhibitor of the present invention has high efficiency. However, compared to Examples 1 and 2, the inhibitory effect was somewhat reduced, and an addition amount of 300–500 ppm is recommended for industrial applications.

[0076] Example 4:

[0077] The purpose of this embodiment is to verify the effectiveness of the present invention under high oxygen content raw materials and high pressure conditions.

[0078] Experimental conditions:

[0079] It is basically the same as Example 1, except that:

[0080] (1) The raw material oil was changed to a high oxygen content simulated oil, and 0.8wt% naphthenic acid was added, with an oxygen content of 0.52% and an acid value of 0.62mgKOH / g;

[0081] (2) The reaction pressure was increased to 8.0 MPa;

[0082] (3) The hydrophobic additive for the catalyst is 4wt% CeO2 + 2wt% ZrO2 (prepared by co-precipitation method);

[0083] (4) Inhibitor addition amount: 400 ppm;

[0084] (5) The amine solution formula was the same as that in Example 1 and was run for 200 hours.

[0085] result:

[0086]

[0087] Conclusion: Under harsh conditions with higher oxygen content, the method of the present invention can still control the total concentration of CO and CO2 at 60 μL / L, control the waste hydrogen emission at 7.2%, and increase the liquid yield by 2.2 percentage points, fully demonstrating the strong adaptability of the technical solution of the present invention.

[0088] Comparative Example 1: No inhibitor was added; only a hydrophobically modified catalyst was used.

[0089] Experimental conditions:

[0090] It is basically the same as Example 1, except that:

[0091] No CO / CO2 generation inhibitors are added;

[0092] The catalyst is NiMo / γ-Al2O3 containing 5wt% CeO2 hydrophobic promoter;

[0093] The reaction temperature was 320℃, the pressure was 6.0 MPa, the hydrogen-to-oil ratio was 400:1, and the space velocity was 1.5 h⁻¹. -1 ;

[0094] The amine solution used is ordinary MDEA solution, without anti-foaming additives. Run for 200 hours.

[0095] result:

[0096]

[0097] Conclusion: Using only the hydrophobically modified catalyst without adding an inhibitor, the total concentration of CO and CO2 decreased from 95 μL / L to 84 μL / L compared to the control experiment in Example 1. Although this is an improvement over the conventional operation in the background art, which completely did not employ the technology of this invention, the effect is far less than the 30 μL / L achieved in Example 1. This indicates that the addition of an inhibitor is a key component in achieving efficient suppression of CO and CO2 generation at the source, and that the hydrophobically modified catalyst and the inhibitor have a synergistic effect.

[0098] Comparative Example 2: No hydrophobic additives were added; only inhibitors and ordinary amine solutions were used.

[0099] Experimental conditions:

[0100] It is basically the same as Example 1, except that:

[0101] (1) The catalyst is ordinary NiMo / γ-Al2O3, without any hydrophobic additives;

[0102] (2) The inhibitor dosage was 300 ppm, the same as in Example 1;

[0103] (3) The amine solution uses ordinary MDEA without adding anti-foaming additives;

[0104] (4) All other reaction conditions are the same. Run for 200 hours.

[0105] result:

[0106]

[0107] Conclusion: Compared with the control experiment in Example 1, adding only the inhibitor without hydrophobic modification of the catalyst reduced the total CO and CO2 concentrations from 95 μL / L in the control experiment to 63 μL / L, a decrease of 33.7%. Although this still achieved some effect, Example 1 reduced the concentrations to 30 μL / L, a decrease of 68.4%, indicating that this comparative example was significantly inferior to Example 1. Furthermore, due to the lack of a hydrophobic additive, the contribution of the water-gas shift reaction was not effectively suppressed. The average ratio of circulating hydrogen CO to CO2 concentration was 0.8, while it was 0.67 in Example 1, indicating a higher ratio in this comparative example. This demonstrates that hydrophobic modification of the catalyst is indispensable for comprehensively suppressing the water-gas shift reaction pathway and achieving more thorough carbon oxide control.

[0108] Summary table of comprehensive comparison between examples and comparative examples

[0109]

[0110] In conclusion, the synergistic effect of catalyst hydrophobic modification, in-situ inhibitor addition, and anti-foaming amine liquid formulation in this invention is indispensable. Using any two of these components alone, such as Comparative Examples 1 and 2, while improving upon the results of using none at all, is far less effective than the combined effect of all three, as seen in Examples 1-4. In particular, Example 1 achieves optimal or near-optimal levels in all five indicators, making it the recommended preferred technical solution.

Claims

1. A method for suppressing CO and CO2 generation and reducing amine foaming in aviation kerosene hydrogenation process, characterized in that, Includes the following steps: Step 1, catalyst modification and loading: A modified hydrogenation catalyst is loaded into the hydrogenation reactor. The modified hydrogenation catalyst includes a support, an active metal component, and a hydrophobic promoter. The hydrophobic promoter is used to inhibit the adsorption of water on the catalyst surface, thereby inhibiting the water-gas shift reaction and the reverse water-gas shift reaction. Step 2, online addition of CO and CO2 generation inhibitors during the reaction: During the hydrogenation reaction, CO and CO2 generation inhibitors are added online to the reaction system. The inhibitors are used to preferentially adsorb onto the decarbonylation / decarboxylation active sites of the catalyst to reduce the selectivity of the decarbonylation / decarboxylation reaction of oxygen-containing compounds. Step 3, anti-foaming operation of the amine desulfurization system: The hydrogenation products are desulfurized using a modified MDEA desulfurization solution, which contains an anti-foaming additive. Step 4, Coordinated control of waste hydrogen emissions and circulating hydrogen purity: Adjust the amount of inhibitor added in real time according to the total concentration of CO and CO2 in the circulating hydrogen; The hydrophobic additive is SO4. 2- The combination of modified TiO2 and In2O3, in which SO4 2- The modified TiO2 accounts for 3% of the mass of the support, and the In2O3 accounts for 2% of the mass of the support. The inhibitor is a compound of maleic anhydride, dimethylformamide and acetylacetone iron in a mass ratio of 10:5:1, and the amount added is 300~500 ppm of the raw oil mass. The anti-foaming agent is a composite of polyether-modified polysiloxane and nano-silica, wherein the mass ratio of polyether-modified polysiloxane to nano-silica is 3:1, and the mass fraction of the anti-foaming additive in the modified MDEA desulfurization solution is 1.2%.

2. The method for suppressing CO and CO2 generation and reducing amine foaming in the aviation kerosene hydrogenation process according to claim 1, characterized in that, In step three, the hydrogenation reaction temperature is 320–350°C, the reaction pressure is 6.0–8.0 MPa, the hydrogen-to-oil volume ratio is 380–450:1, and the liquid hourly space velocity is 1.2–1.8 h⁻¹. -1 .

3. The method for suppressing CO and CO2 generation and reducing amine foaming in the aviation kerosene hydrogenation process according to claim 1, characterized in that, In step four, when the total concentration of CO and CO2 exceeds 50 μL / L, the reaction temperature is reduced by 5–15 °C and / or the hydrogen-to-oil ratio is increased by 10–30%; when the total concentration of CO and CO2 is higher than 80 μL / L, the amount of inhibitor injected is increased to 200–1500 ppm; when the total concentration of CO and CO2 drops below 30 μL / L, the amount of inhibitor injected is reduced to 50–200 ppm.

4. The method for suppressing CO and CO2 generation and reducing amine foaming in the aviation kerosene hydrogenation process according to claim 1, characterized in that, In step three, the operating temperature of the desulfurization system is 42°C, and the amine liquid circulation volume is 1.2 times the theoretical absorption volume. When the foaming height of the amine liquid exceeds 15 mm, polydimethylsiloxane emulsion is injected online as a defoamer, and the injection volume is 30 ppm of the amine liquid circulation volume.

5. The method for suppressing CO and CO2 generation and reducing amine foaming in the aviation kerosene hydrogenation process according to claim 1, characterized in that, Keep waste hydrogen emissions no more than 8% of the total recycled hydrogen.

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