Method for reducing energy consumption for removing CO through catalytic oxidation and application of method

Abstract

The invention relates to the technical field of energy environment, and discloses a method for removing CO through catalytic oxidation and application of the method. The method is carried out in a catalytic oxidation system provided with a reaction unit, and comprises the following steps: in a first gas environment, introducing tail gas to be treated, a noble metal honeycomb catalyst and methanol into the reaction unit, and carrying out a contact reaction to obtain treated gas of which the CO content is less than or equal to 0.005 vol%; the first gas environment contains an oxygen-containing atmosphere, and optionally also contains a hydrogen-containing atmosphere. The CO tail gas generated under various working conditions can be removed by adopting the catalytic oxidation system, the operation is simple, the energy consumption is low, the secondary pollution is avoided, the efficiency is high, the stability is good, and the standard emission of CO and the popularization of a CO removal technology are facilitated.

Description

Technical Field

[0001] The present invention relates to the field of energy and environmental technology, and in particular to a method for removing CO by catalytic oxidation and application thereof. Background Art

[0002] At present, many processes in industrial production will produce CO-rich gases, such as coal gasification, coke oven gas, blast furnace gas and converter gas in steel production. The CO concentration in these gases is high (>5vol%), and direct discharge will cause huge waste of resources and serious environmental pollution. For this type of gas, methods such as cryogenic separation, solvent recovery and solid adsorption separation are usually used to purify, separate and purify CO. The CO content of the purified gas is very low and can be directly discharged in compliance with the standards.

[0003] However, there are some processes that produce tail gas with a low concentration of CO (<5000ppm), such as the desorption gas from the low-temperature methanol washing unit used to remove acidic gases in coal gasification units. For this type of tail gas, the recovery cost is relatively high. In order to meet emission requirements, adsorption, photocatalysis, low-temperature plasma conversion, combustion and other methods are usually used to remove CO in order to meet emission requirements. The catalytic oxidation method introduces a high-efficiency catalyst on the basis of the combustion method to reduce the temperature of the combustion process. It has the advantages of simple process and high removal efficiency, and therefore has received widespread attention.

[0004] However, the use of methods and devices for removing CO tail gas in the existing CO catalytic oxidation technology still has great limitations.

[0005] CN207478277U discloses a system for removing CO from flue gas, which uses an injection device to inject a strong oxidant into the flue, oxidizes the CO in the flue into non-toxic and harmless CO2 and then discharges it from the flue; at the same time, the control unit controls the size of the regulating valve according to the concentration of CO in the flue, and then controls the input amount of the oxidant to ensure that the injected oxidant can complete the conversion of CO in the flue into CO2 and discharge it from the flue, so that the CO emission of the fluidized bed waste incinerator can meet the requirements of GB18485-2014 "Standard for Pollution Control of Domestic Waste Incineration", and also avoids the waste of oxidant and saves costs. However, this system is only applicable to the removal of CO in flue gas generated in the power system process. And the system has high energy consumption, and the treatment effect is average when the concentration of CO in the flue gas is high.

[0006] CN107973271A discloses a reaction device for removing trace carbon monoxide from hydrogen-rich gas and a method for using the same. The problem of uneven material distribution in the limited space of the reaction device for removing trace carbon monoxide from hydrogen-rich gas is improved by reasonably setting a material mixing tank, a raw material distribution port and a gas distribution pipe, and avoiding hot spots to improve the conversion efficiency of the carbon monoxide removal catalyst. However, the method and device are mainly suitable for removing CO from hydrogen-rich gas (hydrogen content is 50-75 vol%).

[0007] Therefore, how to provide a CO catalytic oxidation technology that can remove CO from exhaust gas generated under various working conditions, with low energy consumption, no secondary pollution, high efficiency and good stability is a core problem that needs to be solved urgently in this field. Summary of the invention

[0008] The purpose of the present invention is to overcome the problems that the methods and devices for removing CO tail gas in the prior art have high energy consumption and cannot be applied to tail gas generated under various working conditions while meeting the requirements of no secondary pollution and high removal rate.

[0009] In order to achieve the above object, the first aspect of the present invention provides a method for removing CO by catalytic oxidation, which is carried out in a catalytic oxidation system provided with a reaction unit, comprising:

[0010] In a first gas environment, the tail gas to be treated, the precious metal honeycomb catalyst and methanol are introduced into the reaction unit for contact reaction at 100-350° C. to obtain a treated gas with a CO content of ≤0.005 vol%; the first gas environment contains an oxygen-containing atmosphere and optionally also contains a hydrogen-containing atmosphere;

[0011] The CO content in the tail gas to be treated is 0.05-10 vol%, and the total content of dust particles is not more than 2000 μg / cm 3 ; The particle size of the dust particles is 20-100 μm;

[0012] Based on the total volume of the hydrogen in the hydrogen-containing atmosphere and the tail gas to be treated, the methanol content is less than 0.05 vol%;

[0013] The precious metal honeycomb catalyst contains a first active metal component, which is platinum and / or palladium; based on the total weight of the precious metal honeycomb catalyst, the content of the first active metal component in terms of metal element is 0.5-10wt%;

[0014] Controlling the amount of the oxygen-containing atmosphere introduced so that in the contact reaction system at the initial moment of the contact reaction, the volume concentration ratio of O2 to CO is 5-15:1; and the hydrogen content is 0-5 vol% based on the total volume of the hydrogen in the hydrogen-containing atmosphere, the tail gas to be treated and the introduced methanol;

[0015] The amount of methanol introduced is controlled so that in the contact reaction system at the initial moment of the contact reaction, the methanol content is 0.05-0.5 vol% based on the total volume of the hydrogen in the hydrogen-containing atmosphere, the tail gas to be treated and the introduced methanol.

[0016] The second aspect of the present invention provides application of the method for removing CO by catalytic oxidation described in the first aspect in the field of energy and environmental technology.

[0017] The present invention adopts a catalytic oxidation system to remove CO tail gas generated in various working conditions, and has low energy consumption, no secondary pollution, high efficiency, good stability, and is conducive to CO emission compliance and promotion of CO removal technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic flow chart of a preferred method for removing CO by catalytic oxidation provided by the present invention. DETAILED DESCRIPTION

[0019] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0020] As mentioned above, the first aspect of the present invention provides a method for removing CO by catalytic oxidation, which is carried out in a catalytic oxidation system provided with a reaction unit, comprising:

[0021] In a first gas environment, the tail gas to be treated, the noble metal honeycomb catalyst and methanol are introduced into the reaction unit for contact reaction at 100-350° C. to obtain a treated gas with a CO content of ≤0.005 vol%; the first gas environment contains an oxygen-containing atmosphere and optionally also contains a hydrogen-containing atmosphere;

[0022] The CO content in the tail gas to be treated is 0.05-10 vol%, and the total content of dust particles is not more than 2000 μg / cm 3 ; The particle size of the dust particles is 20-100 μm;

[0023] Based on the total volume of the hydrogen in the hydrogen-containing atmosphere and the tail gas to be treated, the methanol content is less than 0.05 vol%;

[0024] The precious metal honeycomb catalyst contains a first active metal component, which is platinum and / or palladium; based on the total weight of the precious metal honeycomb catalyst, the content of the first active metal component in terms of metal element is 0.5-10wt%;

[0025] Controlling the amount of the oxygen-containing atmosphere introduced so that in the contact reaction system at the initial moment of the contact reaction, the volume concentration ratio of O2 to CO is 5-15:1; and the hydrogen content is 0-5 vol% based on the total volume of the hydrogen in the hydrogen-containing atmosphere, the tail gas to be treated and the introduced methanol;

[0026] The amount of methanol introduced is controlled so that in the contact reaction system at the initial moment of the contact reaction, the methanol content is 0.05-0.5 vol% based on the total volume of the hydrogen in the hydrogen-containing atmosphere, the tail gas to be treated and the introduced methanol.

[0027] Preferably, based on the total volume of the hydrogen in the hydrogen-containing atmosphere and the tail gas to be treated, the content of hydrogen is 0-1 vol%.

[0028] Preferably, the content of sulfide in the tail gas to be treated is 0-0.005 vol%.

[0029] More preferably, the content of sulfide in the tail gas to be treated is 0-0.002 vol%.

[0030] It should be noted that, in the present invention, the sulfide is carbonyl sulfide and hydrogen sulfide.

[0031] Preferably, the exhaust gas to be treated does not contain sulfides, and the CO content in the exhaust gas to be treated is lower than 2 vol%. The amount of methanol introduced is controlled so that in the contact reaction system at the initial moment of the contact reaction, the methanol content is 0.1-0.2 vol%, based on the total volume of the hydrogen in the hydrogen-containing atmosphere, the exhaust gas to be treated and the introduced methanol.

[0032] Preferably, the sulfide content in the tail gas to be treated is 0.001-0.002 vol%, and the CO content in the tail gas to be treated is less than 2 vol%. The amount of methanol introduced is controlled so that in the contact reaction system at the initial moment of the contact reaction, the methanol content is 0.21-0.4 vol%, based on the total volume of the hydrogen in the hydrogen-containing atmosphere, the tail gas to be treated and the introduced methanol.

[0033] Preferably, the sulfide content in the tail gas to be treated is 0.001-0.002 vol%, and the CO content in the tail gas to be treated is ≥2 vol%. The amount of methanol introduced is controlled so that in the contact reaction system at the initial moment of the contact reaction, the methanol content is 0.05-0.09 vol%, based on the total volume of the hydrogen in the hydrogen-containing atmosphere, the tail gas to be treated and the introduced methanol.

[0034] Preferably, the noble metal honeycomb catalyst further comprises a support and a carrier; the support is a monolithic honeycomb ceramic made of cordierite, and the carrier is selected from at least one of alumina, silicon oxide, and zirconium oxide; and

[0035] Based on the total weight of the precious metal honeycomb catalyst, the content of the support is 44-95wt%, and the content of the carrier is 5-30wt%.

[0036] Preferably, the precious metal honeycomb catalyst further contains a second active metal component; the second first active metal component is selected from at least one of iron, cobalt and nickel; and

[0037] Based on the total weight of the noble metal honeycomb catalyst, the content of the second active metal component in terms of metal element is 1-10wt%.

[0038] It should be noted that the present invention has no special requirements on the source of the precious metal honeycomb catalyst. It can be prepared using conventional technical means in the field or purchased commercially. It only needs to ensure that the content of the support, carrier, first active metal component and second active metal component meets the requirements.

[0039] According to a preferred embodiment, the oxygen-containing atmosphere is air.

[0040] It should be noted that the inventors have found that in the present invention, when the hydrogen content in the contact reaction system is not greater than 1 vol%, the solution of the present invention can still be implemented.

[0041] According to a preferred embodiment, the content of hydrocarbon substances in the tail gas to be treated is 0-0.2 vol%.

[0042] It should be noted that in the present invention, the hydrocarbon substance is C 1-4 of hydrocarbons.

[0043] Preferably, the volume concentration of CO in the exhaust gas to be treated and the weight of the first active metal component in the precious metal honeycomb catalyst are in a ratio of 1-10:1, and the volume concentration of CO is expressed in mg / m 3 The amount of the first active metal component used is in mg.

[0044] Preferably, the catalytic oxidation system is further provided with a pretreatment unit, and the method further comprises: before subjecting the tail gas to be treated to the contact reaction, first subjecting the tail gas to be treated to liquid removal and dust removal in the pretreatment unit in sequence to obtain pretreated gas I, and then subjecting the pretreated gas I to the contact reaction;

[0045] The conditions of liquid removal and dust removal are controlled so that the total content of the dust particles in the pre-treated gas I is 0-20 μg / cm 3 .

[0046] Preferably, the pretreatment unit comprises a tail gas buffer tank and a tail gas filter connected in sequence, and the liquid removal and the dust removal are respectively performed in the tail gas buffer tank and the tail gas filter. The inventors have found that in this preferred case, the removal rate of CO removal by catalytic oxidation is higher.

[0047] According to a preferred embodiment, at least one filter element is provided in the exhaust gas filter.

[0048] According to a preferred embodiment, a liquid level gauge is provided on the side of the exhaust gas buffer tank, a drain valve is provided at the bottom, and a safety valve is provided at the top; wherein, the liquid level gauge is used to observe the liquid level in the exhaust gas buffer tank, and when the liquid level in the buffer tank reaches more than 2 / 3, the liquid is discharged through the drain valve; when the pressure in the buffer tank reaches more than 0.2MPa, at least part of the exhaust gas to be treated is discharged between the outer cylinder and the inner cylinder of the inlet and outlet heat exchangers.

[0049] Preferably, a gas mixing unit is further provided in the catalytic oxidation system, and the method further comprises: before the pretreatment gas I and the oxygen-containing atmosphere are subjected to the contact reaction, the pretreatment gas I and the oxygen-containing atmosphere are first introduced into the gas mixing unit for mixing to obtain a mixed gas I, and then the mixed gas I is subjected to the contact reaction with the precious metal honeycomb catalyst and methanol.

[0050] Preferably, an inlet and outlet reaction heat exchanger is provided in the gas mixing unit, and the inlet and outlet reaction heat exchanger includes an inner cylinder and an outer cylinder; and

[0051] The mixing operation includes: introducing the pre-treated gas I and the oxygen-containing atmosphere from an exhaust gas blower and an oxygen-containing atmosphere blower into the inner cylinder of the inlet and outlet reaction heat exchanger for mixing.

[0052] According to a preferred embodiment, the output range of the oxygen-containing atmosphere blower is 0-1000m 3 / h, the oxygen-containing atmosphere blower is provided with a mass controller and a regulating valve, which are used to adjust the output flow rate of the oxygen-containing atmosphere blower according to the CO content in the tail gas to be treated, so that in the contact reaction system at the initial moment of the contact reaction, the ratio of the concentration of O2 to the volume concentration of CO is 5-15:1. The inventors have found that the CO removal effect is the best under this preferred condition, which can ensure that the CO concentration in the treatment obtained after the contact reaction is ≤0.005vol%.

[0053] Preferably, an electric heater and a reaction furnace are provided in the reaction unit, and the method further comprises: before subjecting the mixed gas I to the contact reaction, first heating the mixed gas I and the methanol to 60-280° C. in the electric heater, and then introducing them into the reaction furnace to undergo the contact reaction with the precious metal honeycomb catalyst and the methanol.

[0054] According to a preferred embodiment, a gas distributor is provided on the top of the reaction furnace.

[0055] Preferably, the instantaneous temperature of the contact reaction is measured by respectively arranging thermocouples at the upper, middle and lower parts of one side of the reaction furnace, and the thermocouples are inserted into the precious metal honeycomb catalyst through a sleeve.

[0056] Preferably, the reaction furnace is provided with a temperature interlock, and when the temperature in the reaction furnace exceeds 450° C., the temperature interlock is activated to stop the pretreatment gas I and the oxygen-containing atmosphere from entering the reaction furnace.

[0057] Preferably, the contact reaction temperature is 240-310°C.

[0058] Preferably, the pressure of the contact reaction is 0.05-0.2 MPa.

[0059] Preferably, the method further comprises: exchanging heat between at least a portion of the treated gas and the mixed gas I between the outer cylinder and the inner cylinder of the inlet and outlet reaction heat exchanger.

[0060] The inventors have found that under this preferred condition, the heat utilization efficiency of the system can be improved, energy consumption can be reduced, and the economy of the system can be improved.

[0061] According to a preferred embodiment, the method of the present invention further comprises: using a flue gas analyzer to perform flue gas analysis on the process gas.

[0062] Preferably, when the CO concentration in the treated gas is lower than 0.005 vol%, the treated gas is discharged at a high point.

[0063] Preferably, before the tail gas to be treated is introduced into the tail gas buffer tank, it is first passed through a pressure reducing valve to reduce the pressure to 0.05-0.2 MPa.

[0064] It should be noted that the protection level of the field instrument in the instrument selection used in the present invention is at least IP65, and there is no requirement for the specific selection of various instruments, which can be defined according to the actual type.

[0065] The following combination Figure 1 The preferred specific implementation of the method for removing CO by catalytic oxidation according to the present invention is described, specifically:

[0066] The method is carried out in a catalytic oxidation system provided with a reaction unit;

[0067] (1) removing liquid and removing dust from the tail gas to be treated in a tail gas buffer tank and a tail gas filter in sequence to obtain a pretreated gas I;

[0068] (2) introducing the pre-treated gas I and the oxygen-containing atmosphere from the tail gas blower and the oxygen-containing atmosphere blower into the inner cylinder of the inlet and outlet reaction heat exchanger respectively for mixing to obtain a mixed gas I;

[0069] (3) The methanol is introduced into the electric heater by the methanol feeding system and heated to 60-280° C. and then introduced into the reaction furnace, and the mixed gas I is heated to 60-280° C. in the electric heater and then introduced into the reaction furnace through the gas distributor in the reaction furnace to contact and react with the precious metal honeycomb catalyst and the introduced methanol to obtain the treated gas;

[0070] (4) Use a flue gas analyzer to analyze the CO concentration of the treated gas. When the CO concentration in the treated gas is lower than 0.005 vol%, the treated gas and the mixed gas I are heat exchanged between the outer cylinder and the inner cylinder of the reaction heat exchanger, and the treated gas after the heat exchange is discharged at a high point.

[0071] Preferably, a heat preservation device is provided outside the reaction furnace.

[0072] As mentioned above, the second aspect of the present invention provides the application of the method for removing CO by catalytic oxidation as described in the first aspect in the field of energy and environmental technology.

[0073] The present invention will be described in detail below by way of examples, but the present invention is not limited thereby.

[0074] In the following examples, unless otherwise specified, the chemical reagents used are all products of Sinopharm Chemical Reagent Co., Ltd.

[0075] Unless otherwise specified, the following examples use Figure 1 The process flow shown is carried out.

[0076] Instrument selection: The protection level of the field instrument is IP65;

[0077] Thermocouple: armored Pt100 platinum thermal resistor in accordance with IEC751 standard, accuracy not less than Class A, with reinforcing tube spring compression type, thermal resistor adopts 3-wire system, fixed external thread connection; local temperature indicating instrument uses a protective sleeve with external protection Universal shockproof bimetallic thermometer, with an accuracy level of 1.5;

[0078] Pressure instrument: Remote pressure / differential pressure measurement uses intelligent pressure / differential pressure transmitters with digital gauges, pressure transmitters with stainless steel two-valve group, differential pressure transmitters with stainless steel three-valve group, transmitter accuracy ≤±0.075%; local pressure instruments use dials with a diameter of Shockproof stainless steel spring tube pressure gauge, accuracy is 1.5;

[0079] Quality controller: Equip the throttling device with a differential pressure transmitter;

[0080] Liquid level meter: magnetic flap liquid level meter;

[0081] Control valve: The valve body is made of carbon steel, the valve core is made of stainless steel, and the valve pressure level is not lower than the pressure level of the process pipeline;

[0082] Flue gas analyzer: Model: Testo350, purchased from Testo Instrument International Trading (Shanghai) Co., Ltd.

[0083] Example 1

[0084] This example is used to illustrate the method for removing CO by catalytic oxidation provided by the present invention. The method refers to the parameters in Table 2 and is carried out in a catalytic oxidation system provided with a reaction unit, and the first gas environment does not contain a hydrogen-containing atmosphere, specifically;

[0085] (1) The tail gas to be treated is passed through a pressure reducing valve to reduce the pressure to 0.1 MPa, and then liquid removal and dust removal are performed in the tail gas buffer tank and the tail gas filter equipped with a filter element, respectively, to obtain a total content of dust particles of 20 μg / cm 3 Pre-treated gas I;

[0086] The composition of the tail gas to be treated is shown in Table 1. By observing the liquid level gauge on the side of the tail gas buffer tank, when the liquid level of the buffer tank reaches 2 / 3, the liquid is discharged through the drain valve at the bottom of the tail gas buffer tank; when the pressure of the buffer tank reaches 0.2MPa, a part of the tail gas to be treated is discharged between the outer cylinder and the inner cylinder of the inlet and outlet heat exchangers;

[0087] (2) introducing the pre-treated gas I and the oxygen-containing atmosphere (air) from the tail gas blower and the oxygen-containing atmosphere blower into the inner cylinder of the inlet and outlet reaction heat exchanger respectively for mixing to obtain a mixed gas I;

[0088] The amount of the oxygen-containing atmosphere introduced is controlled by a mass controller and a regulating valve provided on the oxygen-containing atmosphere blower, so that the volume concentration ratio of O2 to CO in the contact reaction system at the initial moment of the contact reaction is 5:1;

[0089] (3) The methanol is introduced into the electric heater by the methanol feeding system and heated to 180°C and then introduced into the reactor, and the mixed gas I is heated to 180°C in the electric heater and then introduced into the reactor through the gas distributor in the reactor; wherein, the amount of methanol introduced is controlled so that in the contact reaction system at the initial moment of the contact reaction, the total volume of the tail gas to be treated and the introduced methanol is taken as the reference, and the methanol content is 0.15 vol%, and the noble metal honeycomb catalyst and the introduced methanol are contacted and reacted in the reactor at 240°C and a pressure of 0.1 MPa to obtain a treated gas, and a flue gas analyzer is used to analyze the CO concentration of the treated gas, and the CO content is 0.002 vol%, which meets the enterprise standard of a concentration of less than 0.01 vol%, and the treated gas and the mixed gas I are heat exchanged between the outer cylinder and the inner cylinder of the inlet and outlet reaction heat exchanger, and the treated gas after the heat exchange is discharged at a high point;

[0090] Wherein, the instantaneous temperature of the contact reaction is measured by respectively setting thermocouples at the upper, middle and lower parts of one side of the reactor, and the thermocouples are inserted into the precious metal honeycomb catalyst through a sleeve; when the temperature in the reactor exceeds 450°C, the temperature interlock on the reactor is activated, and the pretreatment gas I and the oxygen-containing atmosphere are stopped from being passed into the reactor;

[0091] The precious metal honeycomb catalyst is a platinum-alumina catalyst, wherein the support is a monolithic honeycomb ceramic with cordierite material, the carrier is alumina, the second active metal component is iron, and the first active metal component is platinum; and based on the total weight of the precious metal honeycomb catalyst, the content of the support is 70wt%, the content of the carrier is 25wt%, the content of the second active metal component in terms of metal element is 2wt%, and the content of the first active metal component is 1wt%;

[0092] The relationship between the volume concentration of CO in the exhaust gas to be treated and the weight of the first active metal component in the precious metal honeycomb catalyst is 1:1;

[0093] The CO content in the final treated gas is 0.002 vol%, which meets the enterprise standard of concentration below 0.01 vol%.

[0094] Example 2

[0095] This embodiment is carried out in a similar manner to that of Embodiment 1, except that the composition of the exhaust gas to be treated is changed, and the precious metal honeycomb catalyst is a palladium-alumina catalyst, wherein the support is a monolithic honeycomb ceramic made of cordierite, the carrier is alumina, the second active metal component is iron, and the first active metal component is palladium; and based on the total weight of the precious metal honeycomb catalyst, the content of the support is 68wt%, the content of the carrier is 25wt%, the content of the second active metal component in terms of metal element is 2wt%, and the content of the first active metal component is 1wt%;

[0096] The amount of methanol introduced is controlled so that in the contact reaction system at the initial moment of the contact reaction, the methanol content is 0.3 vol% based on the total volume of the tail gas to be treated and the introduced methanol.

[0097] The methanol is introduced into the electric heater by the methanol feeding system and heated to 240°C before being introduced into the reactor. The mixed gas I is heated to 240°C in the electric heater and then introduced into the reactor through the gas distributor in the reactor. The contact reaction is at 300°C. For specific parameters, see Table 2. The CO content in the treated gas finally obtained is 0.002 vol%, which meets the enterprise standard of a concentration below 0.01 vol%.

[0098] Example 3

[0099] This embodiment is carried out in a similar manner to that of Embodiment 1, except that the composition of the exhaust gas to be treated is changed, and the precious metal honeycomb catalyst is a platinum-alumina catalyst, wherein the support is a monolithic honeycomb ceramic made of cordierite, the carrier is alumina, the second active metal component is cobalt, and the first active metal component is platinum; and based on the total weight of the precious metal honeycomb catalyst, the content of the support is 65wt%, the content of the carrier is 25wt%, the content of the second active metal component in terms of metal element is 2wt%, and the content of the first active metal component is 5wt%;

[0100] Controlling the amount of methanol introduced so that in the contact reaction system at the initial moment of the contact reaction, the methanol content is 0.07 vol% based on the total volume of the tail gas to be treated and the introduced methanol;

[0101] The methanol is introduced into the electric heater by the methanol feeding system and heated to 220°C before being introduced into the reactor. The mixed gas I is heated to 220°C in the electric heater and then introduced into the reactor through the gas distributor in the reactor. The contact reaction is at 280°C. For specific parameters, see Table 2. The CO content in the treated gas finally obtained is 0.002 vol%, which meets the enterprise standard of a concentration below 0.01 vol%.

[0102] Example 4

[0103] This example is carried out in a similar manner to Example 1, except that the composition of the tail gas to be treated is changed, and the condition parameters of the contact reaction are different. For specific parameters, see Table 2;

[0104] Controlling the amount of methanol introduced so that, in the contact reaction system at the initial moment of the contact reaction, the methanol content is 0.4 vol% based on the total volume of the tail gas to be treated and the introduced methanol;

[0105] Among them, methanol is introduced into the electric heater by the methanol feeding system and heated to 240°C before being introduced into the reactor. The mixed gas I is heated to 240°C in the electric heater and then introduced into the reactor through the gas distributor in the reactor. The contact reaction is 310°C. The CO content in the final treated gas is 0.004 vol%, which meets the enterprise standard of concentration below 0.01 vol%.

[0106] Example 5

[0107] This embodiment is carried out in a similar manner to that of Embodiment 1, except that the amount by weight of the first active metal component in the precious metal honeycomb catalyst is different and meets the following requirements: the volume concentration of CO in the exhaust gas to be treated and the amount by weight of the first active metal component in the precious metal honeycomb catalyst are in a relationship of 12:1; the CO content in the treated gas obtained at last is 0.009 vol%, which meets the enterprise standard of a concentration lower than 0.01 vol%.

[0108] Comparative Example 1

[0109] This comparative example is carried out in a method similar to that of Example 1, except that the precious metal honeycomb catalyst is a silver-alumina catalyst, wherein the support is a monolithic honeycomb ceramic made of cordierite, the carrier is alumina, the second active metal component is iron, and the first active metal component is silver; and based on the total weight of the precious metal honeycomb catalyst, the content of the support is 70wt%, the content of the carrier is 25wt%, the content of the second active metal component in terms of metal element is 2wt%, and the content of the first active metal component is 1wt%; the CO content in the finally obtained treated gas is 0.1vol%, which does not meet the enterprise standard of a concentration lower than 0.01vol%.

[0110] Comparative Example 2

[0111] This comparative example is carried out in a method similar to that of Example 1, except that the precious metal honeycomb catalyst is a platinum-alumina catalyst, wherein the support is a monolithic honeycomb ceramic made of cordierite, the carrier is alumina, the second active metal component is cobalt, and the first active metal component is platinum; and based on the total weight of the precious metal honeycomb catalyst, the content of the support is 72wt%, the content of the carrier is 25wt%, the content of the second active metal component in terms of metal element is 2wt%, and the content of the first active metal component is 0.2wt%; the CO content in the finally obtained treated gas is 0.2vol%, which does not meet the enterprise standard of a concentration lower than 0.01vol%.

[0112] Comparative Example 3

[0113] This comparative example is carried out using a method similar to that of Example 1, except that in the contact reaction system at the initial moment of the contact reaction, the volume concentration ratio of O2 to CO is 4:1; the CO content in the finally obtained treated gas is 0.15 vol%, which does not meet the enterprise standard of a concentration lower than 0.01 vol%.

[0114] Comparative Example 4

[0115] This comparative example is carried out using a method similar to that of Example 1, wherein the same steps as those of Example 1 include: introducing methanol into an electric heater through a methanol feeding system and heating it to 180°C before introducing it into the reaction furnace, and heating the mixed gas I in the electric heater to 180°C before introducing it into the reaction furnace through a gas distributor in the reaction furnace.

[0116] The difference is that in step (3), methanol is not introduced, that is, the mixed gas I is directly contacted with the precious metal honeycomb catalyst for reaction, and the contact reaction temperature is 180°C; the CO content in the final treated gas is 0.009 vol%, which can meet the enterprise standard of concentration below 0.01 vol%.

[0117] Comparative Example 5

[0118] This comparative example is carried out in a similar manner to comparative example 4, except that methanol is introduced into the electric heater by the methanol feeding system and heated to 240°C before being introduced into the reactor, and the mixed gas I is heated to 240°C in the electric heater and then introduced into the reactor through the gas distributor in the reactor for contact reaction, and the contact reaction temperature is 240°C.

[0119] Finally, the treated gas with the same CO content as in Example 1 can be obtained, wherein the CO content is 0.002 vol%, which can meet the enterprise standard of concentration below 0.01 vol%, but the energy consumption is relatively high.

[0120] Comparative Example 6

[0121] This comparative example is carried out in a similar manner to Example 1, except that in step (3), the amount of methanol introduced is controlled so that in the contact reaction system at the initial moment of the contact reaction, the methanol content is 0.6 vol% based on the total volume of the tail gas to be treated and the methanol;

[0122] Finally, the device experienced a temperature runaway problem, causing the device's temperature interlock to be activated, resulting in the device being unable to remove CO gas normally.

[0123] Table 1

[0124] Content of tail gas to be treated Example 1 Example 2 Example 3 Example 4 CO(vol%) 1.5 1.0 1.2 1.1 <![CDATA[H2(vol%)]]> 0.02 0 0.01 0 Methanol (vol%) 0.02 0.03 0.045 0.05 Sulfide (vol%) 0 0.0015 0.0012 0.004 Hydrocarbons (vol%) 0 0.2 0 0.15 <![CDATA[Dust particulate matter (μg / cm 3 )]]> 1200 1400 1000 1800

[0125] Note: The sulfides mentioned are carbonyl sulfide and hydrogen sulfide;

[0126] The hydrocarbon substance is C 1-4 of hydrocarbons;

[0127] The particle size of dust particles is 20-100μm.

[0128] Table 2

[0129]

[0130]

[0131] Note: The relationship between the amount of CO and active metal is: CO volume concentration (mg / m 3 ) and the ratio of the weight (mg) of the first active metal component in the precious metal honeycomb catalyst.

[0132] From the above results, it can be seen that the present invention adopts a catalytic oxidation system, which can remove CO tail gas under various working conditions, and especially can effectively remove CO from tail gas under non-hydrogen-rich conditions. The method has good treatment effect, simple process, and convenient operation. In particular, it can reduce energy consumption and can reduce the external heat provided in the process of catalytic oxidation to remove CO. Specifically, under the premise of the same treatment effect, the present invention can reduce the temperature of heating methanol and mixed gas I using an electric heater by at least 60°C, and there is no secondary pollution, and has good application prospects.

[0133] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for removing CO by catalytic oxidation, characterized in that: The method is carried out in a catalytic oxidation system provided with a reaction unit, comprising: In a first gas environment, the tail gas to be treated, the noble metal honeycomb catalyst and methanol are introduced into the reaction unit for contact reaction at 100-350° C. to obtain a treated gas with a CO content of ≤0.005 vol%; the first gas environment contains an oxygen-containing atmosphere and optionally also contains a hydrogen-containing atmosphere; The CO content in the tail gas to be treated is 0.05-10 vol%, and the total content of dust particles is not more than 2000 μg / cm 3 ; The particle size of the dust particles is 20-100 μm; Based on the total volume of the hydrogen in the hydrogen-containing atmosphere and the tail gas to be treated, the methanol content is less than 0.05 vol%; The precious metal honeycomb catalyst contains a first active metal component, which is platinum and / or palladium; based on the total weight of the precious metal honeycomb catalyst, the content of the first active metal component in terms of metal element is 0.5-10wt%; Controlling the amount of the oxygen-containing atmosphere introduced so that in the contact reaction system at the initial moment of the contact reaction, the volume concentration ratio of O2 to CO is 5-15:1; and the hydrogen content is 0-5 vol% based on the total volume of the hydrogen in the hydrogen-containing atmosphere, the tail gas to be treated and the introduced methanol; The amount of methanol introduced is controlled so that in the contact reaction system at the initial moment of the contact reaction, the methanol content is 0.05-0.5 vol% based on the total volume of the hydrogen in the hydrogen-containing atmosphere, the tail gas to be treated and the introduced methanol.

2. The method according to claim 1, wherein: Based on the total volume of the hydrogen in the hydrogen-containing atmosphere and the tail gas to be treated, the content of hydrogen is 0-1 vol%.

3. The method according to claim 1 or 2, wherein: The content of sulfide in the tail gas to be treated is 0-0.005 vol%; Preferably, the content of sulfide in the tail gas to be treated is 0-0.002 vol%.

4. The method according to claim 3, wherein: The exhaust gas to be treated does not contain sulfides, and the CO content in the exhaust gas to be treated is lower than 2 vol%. The amount of methanol introduced is controlled so that in the contact reaction system at the initial moment of the contact reaction, the methanol content is 0.1-0.2 vol% based on the total volume of the hydrogen in the hydrogen-containing atmosphere, the exhaust gas to be treated and the introduced methanol.

5. The method according to claim 3, wherein: The sulfide content in the tail gas to be treated is 0.001-0.002 vol%, and the CO content in the tail gas to be treated is lower than 2 vol%. The amount of methanol introduced is controlled so that in the contact reaction system at the initial moment of the contact reaction, the methanol content is 0.21-0.4 vol% based on the total volume of the hydrogen in the hydrogen-containing atmosphere, the tail gas to be treated and the introduced methanol.

6. The method according to claim 3, wherein: The sulfide content in the tail gas to be treated is 0.001-0.002 vol%, and the CO content in the tail gas to be treated is ≥2 vol%. The amount of methanol introduced is controlled so that in the contact reaction system at the initial moment of the contact reaction, the methanol content is 0.05-0.09 vol% based on the total volume of the hydrogen in the hydrogen-containing atmosphere, the tail gas to be treated and the introduced methanol.

7. The method according to any one of claims 1 to 6, wherein: The volume concentration of CO in the exhaust gas to be treated and the weight of the first active metal component in the precious metal honeycomb catalyst are in a relationship of 1-10:

1. The volume concentration of CO is expressed in mg / m 3 The amount of the first active metal component used is in mg.

8. The method according to any one of claims 1 to 6, wherein: The catalytic oxidation system is also provided with a pretreatment unit, and the method further comprises: before subjecting the tail gas to be treated to the contact reaction, first subjecting the tail gas to be treated to liquid removal and dust removal in the pretreatment unit in sequence to obtain pretreated gas I, and then subjecting the pretreated gas I to the contact reaction; The conditions of liquid removal and dust removal are controlled so that the total content of the dust particles in the pre-treated gas I is 0-20 μg / cm 3 .

9. The method according to claim 8, wherein: The pretreatment unit comprises an exhaust gas buffer tank and an exhaust gas filter which are connected in sequence, and the liquid removal and the dust removal are respectively performed in the exhaust gas buffer tank and the exhaust gas filter.

10. The method according to claim 8 or 9, wherein: The catalytic oxidation system is also provided with a gas mixing unit, and the method further includes: before the pre-treatment gas I and the oxygen-containing atmosphere are subjected to the contact reaction, the pre-treatment gas I and the oxygen-containing atmosphere are first introduced into the gas mixing unit for mixing to obtain a mixed gas I, and then the mixed gas I is subjected to the contact reaction with the precious metal honeycomb catalyst and methanol.

11. The method according to claim 10, wherein: An inlet and outlet reaction heat exchanger is arranged in the gas mixing unit, and the inlet and outlet reaction heat exchanger comprises an inner cylinder and an outer cylinder; as well as The mixing operation includes: introducing the pre-treated gas I and the oxygen-containing atmosphere from an exhaust gas blower and an oxygen-containing atmosphere blower into the inner cylinder of the inlet and outlet reaction heat exchanger for mixing.

12. The method according to claim 10 or 11, wherein: The reaction unit is provided with an electric heater and a reaction furnace, and the method further comprises: before subjecting the mixed gas I to the contact reaction, first heating the mixed gas I and the methanol to 60-280° C. in the electric heater, and then introducing them into the reaction furnace to undergo the contact reaction with the precious metal honeycomb catalyst and methanol.

13. The method according to any one of claims 1 to 12, wherein: The contact reaction temperature is 240-310°C; and / or The pressure of the contact reaction is 0.05-0.2 MPa.

14. The method according to any one of claims 11 to 13, wherein: The method further comprises: performing heat exchange between the outer cylinder and the inner cylinder of the inlet and outlet reaction heat exchanger by at least a portion of the treated gas, the tail gas to be treated and the oxygen-containing atmosphere.

15. Application of the method for removing CO by catalytic oxidation as described in any one of claims 1 to 14 in the field of energy and environmental technology.

Images