CN116037192A - Catalyst for deep removal of carbon monoxide under hydrogen-rich condition, preparation method and application - Google Patents

Abstract

The invention discloses a catalyst for deep removal of carbon monoxide under a hydrogen-rich condition, a preparation method and application thereof; the proton exchange membrane hydrogen fuel cell has strict requirements on impurity gas in a hydrogen source, especially the content of C0, and the safety of the cell can be ensured only by controlling the content below 0.2 ppm. In the conventional adsorption technology, it is difficult to realize CO and N ₂ Inert gases such as Ar and the like are adsorbed separately, and in the catalytic oxidation removal technology, C0 and H ₂ And it is difficult to achieve selective catalytic oxidation. Therefore, the difficulty of deep removal of C0 is great, the invention develops a catalyst for efficiently removing C0 aiming at the carbon monoxide preferential catalytic oxidation technology, and the catalyst can remove 1% C0/H at 75-95 DEG C ₂ The content of C0 in the mixed gas is removed to below 0.2ppm, thereby meeting the severe requirement of hydrogen for fuel cells on the concentration of C0 impurities.

Description

Catalyst for deep removal of carbon monoxide under hydrogen-rich condition, preparation method and application

Technical Field

The invention relates to the field of gas purification, in particular to a catalyst for deep removal of carbon monoxide gas under a hydrogen-rich condition, and a preparation method and application thereof.

Background

In the global energy large background of carbon neutralization, hydrogen is taken as a clean energy which can be stored, can generate electricity and can burn, and has become one of the important strategic directions of energy transformation in the world. The proton exchange membrane hydrogen fuel cell can be used in the traffic field, can be used as a flexible and controllable clean voltage for grid-connected power generation, can relieve the peak regulation pressure of a power grid, and can improve the new energy consumption capability of the power grid.

The raw material gas for the hydrogen fuel cell after the purification of the industrial byproduct hydrogen has wide sources, low price and environmental protection, and is suitable for large-scale production. The high-purity hydrogen is prepared by the method for purifying the industrial byproduct hydrogen, so that the cost is saved, the treatment and recycling of the industrial waste gas can be realized, the large-scale production is easy, and the problems of the cost of the power grid to the hydrogen of the fuel cell and the large-scale storage and transportation can be solved. China is the largest industrial byproduct hydrogen country worldwide, so China has the unique condition of utilizing byproduct hydrogen. Therefore, the raw material gas for hydrogen fuel cells after purification of industrial by-product hydrogen is considered as an important source of recent development of hydrogen energy.

However, the proton exchange membrane hydrogen fuel cell is very sensitive to impurity gas, and is easy to damage core components. Therefore, the proton exchange membrane hydrogen fuel cell has strict requirements on impurity gas in a hydrogen source, and not only H is the fuel hydrogen for the proton exchange membrane fuel cell automobile according to national standard GB/T37244-2018 ₂ The purity requirement is more than or equal to 99.97%, and the content requirement is further made for 14 impurities such as CO, sulfide and the like. Especially, the content of CO is controlled below 0.2ppm to ensure the safety of the battery. The traditional adsorption technology is difficult to realize CO and N ₂ And Ar (less than or equal to 100 ppm) and other inert gases, and CO and H are separated and adsorbed ₂ And it is difficult to achieve selective catalytic oxidation. Thus, the difficulty of deep removal of CO is great.

According to the current publications and literature, CO selective catalytic oxidation technology is one of the most cost effective methods among the numerous methods for CO removal. In the past ten years, many research teams at home and abroad have been availableA number of catalysts have been developed for CO-preferential catalytic oxidation (CO-PROX), including supported Au catalysts, supported Pt catalysts, and non-noble metal catalysts. However, in a selective oxidation reaction system of CO under the condition of rich hydrogen, the oxidation of CO and the oxidation of H2 have a competitive relationship in the reaction. Furthermore, if the reaction temperature is too high, methanation of CO and Reverse Water Gas Shift (RWGS) side reactions also occur. Therefore, to achieve deep removal of CO in hydrogen rich gas, research and preparation of a catalyst with high activity, high selectivity and high stability is a key of the technology. In addition, in industrial gas purification, "low temperature" is critical to the economy and safety of the decontamination process, directly related to the cost of the purified hydrogen source. In summary, such catalysts should be provided with: (1) high activity is maintained at low temperature; (2) Has excellent CO oxidation selectivity, i.e. no CO and H generation ₂ O and O ₂ And H is ₂ Is carried out by a reaction; (3) good hydrothermal stability.

In recent years, platinum-based catalysts have received great attention due to their remarkable low temperature activity. It is in CO/H ₂ The catalytic oxidation reaction shows excellent CO selectivity. However, achieving high selectivity and high activity of CO at low temperatures remains a great challenge. Therefore, under the condition of hydrogen enrichment, the CO removal catalyst with both low-temperature high activity and high selectivity is a problem to be solved urgently by hydrogen purification technology for high-quality fuel cells.

In addition, in the aspect of detecting the content of CO, most of the current literature reports adopt chromatography with a TCD detector, and the detection limit of CO of a gas chromatograph with the TCD detector is more than 10ppm due to the sensitivity of the TCD detector. Thus, although the chromatographic data of the TCD detector show a CO conversion of 100%, it is still not possible to determine whether the CO content can actually be reduced to the 0.2ppm level.

Disclosure of Invention

The invention aims to overcome the defects in the background technology and provides a catalyst for deep CO removal under a hydrogen-rich condition and a preparation and use method thereof. The catalyst is capable of converting 1% CO/H at 75-95 DEG C ₂ The CO content of the mixed gas is removed to be below 0.2ppm, so that the CO concentration of the fuel cell is metAnd (5) solving.

The specific technical scheme of the invention is as follows:

a preparation method of a catalyst for deep CO removal under a hydrogen-rich condition is characterized by comprising the following steps of: the method comprises the following steps:

step 1: under the stirring state at room temperature, dissolving urea phosphate in water, then soaking the urea phosphate on a coconut carbon carrier, standing, drying, loading the coconut carbon carrier into a tube furnace, heating up and maintaining for at least 3 hours under flowing inert atmosphere, and then cooling to room temperature, so that the urea phosphate is fully doped with nitrogen and phosphorus, and obtaining the nitrogen and phosphorus modified coconut carbon carrier;

step 2: under a certain temperature stirring state, potassium chloride is dissolved in deionized water, after stirring and dissolution, the potassium chloride is soaked on a nitrogen-phosphorus modified coconut carbon carrier by adopting an isovolumetric soaking method, and after standing for at least 2 hours at room temperature, the coconut carbon carrier is dried; and dissolving chloroplatinic acid and N-methylsuccinimide in deionized water, stirring and dissolving, then continuously stirring, immersing the obtained solution in the carrier by using an isovolumetric immersion method, standing at room temperature for at least 12h, drying and loading into a tubular furnace, heating and reducing for at least 3h under flowing hydrogen atmosphere, fully reducing metal components, cooling to room temperature, and then switching to flowing inert atmosphere and purging for at least 2h to obtain the required catalyst.

Preferably, it is: the step 1 further comprises the following steps: dissolving urea phosphate in water, soaking the urea phosphate on a coconut shell carbon carrier, standing for at least 12 hours, thoroughly drying the urea phosphate at 100-150 ℃, then loading a sample into a tube furnace, heating to 650-800 ℃ under flowing inert atmosphere and maintaining the temperature for at least 3 hours, and then cooling to room temperature under flowing inert atmosphere to obtain a nitrogen-phosphorus modified coconut shell carbon carrier; wherein the dosage of the urea phosphate accounts for 10-20% of the mass of the coconut shell carbon, the inert atmosphere is one or more of nitrogen, argon and helium, and the gas airspeed of the inert atmosphere is 3000-12000h ^-1 The inert gas atmosphere for modifying the carrier is ensured, the generated decomposed waste gas is taken away in time, and meanwhile, the reaction temperature fluctuation is not large or the modified carrier is blown away from the reaction zone of the tubular furnace due to too fast air flow;

preferably, it is: the step 2 further comprises the following stepsThe volume is as follows: dissolving potassium chloride in deionized water under the stirring state of 50-60 ℃, soaking the potassium chloride on a nitrogen-phosphorus modified coconut carbon carrier by adopting an equal volume soaking method after stirring and dissolving, standing at room temperature for at least 2 hours, and thoroughly drying the coconut carbon carrier at 80-95 ℃; dissolving chloroplatinic acid and N-methylsuccinimide in deionized water, stirring for dissolving, continuing stirring for at least 1h, soaking the obtained solution in the carrier by an isovolumetric soaking method, standing at room temperature for at least 12h, thoroughly drying at 80-95 ℃, loading a sample into a tubular furnace, heating to 400-450 ℃ under flowing hydrogen atmosphere, reducing for at least 3h, cooling to room temperature, switching to flowing inert atmosphere, and continuing to purge for at least 2h to obtain the required catalyst; wherein the dosage of chloroplatinic acid accounts for 2-5% of the mass of the nitrogen-phosphorus modified coconut carbon carrier, the mol ratio of the chloroplatinic acid to the N-methyl succinimide is 1:2-1:3, the dosage of potassium chloride accounts for 2-3% of the mass of the nitrogen-phosphorus modified coconut carbon carrier, and the gas space velocity of hydrogen is 1800-9600h ^-1 The gas space velocity of the inert atmosphere is 1800-9600h ^-1 。

Preferably, it is: replacing N-methyl succinimide with N-ethyl succinimide; the molar ratio of chloroplatinic acid to N-ethylsuccinimide is 1:2-1:3.

Preferably, it is: n-methyl succinimide is replaced by succinimide, and the molar ratio of chloroplatinic acid to the succinimide is 1:2-1:3.

Preferably, it is: the specific surface area of the coconut shell carbon is more than 1000m ² And/g, so as to ensure that as many load micropore channels as possible are provided for the metal active site, reduce the size of load metal and relieve the agglomeration of metal particles in a high-temperature link.

The invention also discloses a catalyst for deep CO removal under the hydrogen-rich condition, which is characterized by being obtained by using the preparation method.

The invention also discloses a use method of the catalyst, and the catalyst is prepared by the method; the method is characterized by comprising the following steps of:

(1) Grinding the catalyst, sieving to obtain small particles with particle diameter in the range of 1/15-1/20 of the inner diameter of the fixed bed reaction tubeThe range size can ensure the airspeed to be 1500-6000h ^-1 When the gas passes through the fixed bed, the gas resistance is not excessively large, and meanwhile, the gas can fully contact with the catalyst to complete the catalytic reaction;

(2) Loading the sieved catalyst particles into a constant temperature zone of a constant pressure fixed bed reactor, and adding active carbon or quartz sand on the upper layer of the catalyst as a gas preheating layer;

(3) In the flowing 5% O ₂ /N ₂ Heating the catalyst to 75-95 ℃ in the mixed gas atmosphere (the temperature is the preferable temperature range of the CO catalytic oxidation reaction in the method, the catalytic activity is greatly reduced below 75 ℃, and the design concept of the low-temperature energy-saving catalytic oxidation is not met when the temperature is higher than 95 ℃), and then introducing 1% CO/H ₂ The mixed gas starts to react; wherein 1% CO/H ₂ The gas space velocity of the mixed gas is 1500-6000h ^-1 ，(≤6000h ^-1 Can ensure that the mixed gas can fully complete the catalytic reaction after passing through the catalyst fixed bed in the method by adjusting 5 percent of O ₂ /N ₂ The flow rate of the mixed gas is used for maintaining the ratio of CO to O ₂ The volume ratio of (2) is 1:0.6-1:0.8 to ensure that the CO component is fully oxidized and not too much excess O is introduced ₂ Impurities;

(4) The concentration change before and after the CO reaction was detected by using a gas chromatograph equipped with a methane reformer and FID detection.

Compared with the prior art, the invention has the advantages that:

(1) The urea phosphate with the mass content of 10-20% is required to carry out nitrogen-phosphorus double modification on the coconut shell carbon carrier so as to increase the content of nitrogen and phosphorus sites in the carrier and improve the number of metal anchoring sites. Too much or too little mass of urea phosphate seriously affects the activity of the catalyst. And carrying out heat treatment for at least 3 hours at 650-800 ℃ under flowing inert atmosphere, wherein the flowing inert atmosphere can take away small molecules which do not react with the carrier after decomposition while decomposing urea phosphate, so that the product after decomposing urea phosphate is prevented from blocking the pore channels of the carrier. Meanwhile, water molecules generated by decomposition of urea phosphate at high temperature can also act with the coconut shell carbon carrier to generate a certain etching effect on the pore canal. In addition, since nitrogen and phosphorus are less electronegative than oxygen, in the nitrogen and phosphorus double modified coconut carbon carrier, the combination of nitrogen and phosphorus sites and metal centers can reduce the degree of charge offset compared with carbonyl groups in coconut carbon. This makes the metal component in contact with the support more nearly lower in valence and more susceptible to redox reactions.

(2) Since potassium chloride and chloroplatinic acid react in water to form potassium chloroplatinate which is sparingly soluble in water, this results in precipitation and agglomeration of the platinum species in water, thereby affecting complexation of the platinum species with the organic ligand. In addition, insoluble potassium chloroplatinate precipitates are also difficult to enter into the micropores of the activated carbon, and the dispersibility of platinum species in the catalyst is affected. Thus, in the present invention we use the step-wise impregnation method as follows: firstly, dipping potassium chloride on the nitrogen-phosphorus modified coconut shell carbon carrier, drying, and then dipping for the second time to upload platinum species, so that the dispersibility of the platinum species is not affected. Meanwhile, potassium ions can be combined with carbonyl groups on the surface of the coconut shell carbon carrier preferentially, and the electron auxiliary agent K+ can generate electron offset towards oxygen atoms through a Pt-O-K form due to lower electronegativity of K, so that the electron offset degree of Pt towards the oxygen atoms is weakened, and the Pt atoms on the surface of the nano particles are more close to a low valence state. In addition, the dosage of the potassium chloride accounts for 2-3% of the mass of the nitrogen-phosphorus modified coconut shell carbon carrier, and too little or too much can lead to poor catalyst performance; because the potassium chloride is too little to play a role of enough electron auxiliary agent, too much can block the catalyst pore canal and easily bury the metal active site.

(3) Because the active center of the Pt-based catalyst required by CO selective catalytic oxidation reaction is a zero-valent Pt nano particle, a ligand with too strong complexing capacity cannot be selected in the preparation process of the catalyst. In contrast, if the size of the Pt nanoparticles prepared is too large, the catalytic activity thereof is greatly reduced, and the preferential selective catalytic oxidation of CO at low temperature cannot be satisfied. The invention finally adopts dicarbonyl ligand N-methyl succinimide, N-ethyl succinimide or succinimide to stabilize and disperse platinum ions, and the three dicarbonyl ligands can play the role of a soft template to avoid agglomeration of platinum species in the processes of dipping and drying. The highly dispersed small-sized Pt nanoparticles were then obtained by heating to 400-450 ℃ under a flowing hydrogen atmosphere and reducing for at least 3 hours. The reduction temperature cannot be too high, otherwise, phosphorus on the surface of the carrier reacts with platinum at high temperature to obtain metal phosphide, so that the activity of the catalyst is reduced; in addition, the high temperature can also cause the growth and aggregation of Pt nano particles, and the activity of the catalyst can also be reduced. Meanwhile, the molar ratio of chloroplatinic acid to N-ethylsuccinimide is 1:2-1:3, and too little or too much dicarbonyl ligand is used to influence the performance of the catalyst, so that the removal of CO can not reach the standard of a fuel cell.

Drawings

FIG. 1 is a transmission electron micrograph of the catalyst prepared in example 1.

FIG. 2 catalyst stability test and H ₂ Content detection result (85 ℃, GHSV) _CO ＝3000h ^-1 )。

Detailed Description

The technical scheme of the invention will be further described in detail below with reference to specific embodiments. The purpose of the illustrated embodiments is to further illustrate the present invention.

A preparation method of a catalyst for deep OO removal under a hydrogen-rich condition is characterized by comprising the following steps: the method comprises the following steps:

step 1: under the stirring state at room temperature, dissolving urea phosphate in water, then soaking the urea phosphate on a coconut carbon carrier, standing, drying, loading the coconut carbon carrier into a tube furnace, heating up and maintaining for at least 3 hours under flowing inert atmosphere, and then cooling to room temperature, so that the urea phosphate is fully doped with nitrogen and phosphorus, and obtaining the nitrogen and phosphorus modified coconut carbon carrier;

step 2: under a certain temperature stirring state, potassium chloride is dissolved in deionized water, after stirring and dissolution, the potassium chloride is soaked on a nitrogen-phosphorus modified coconut carbon carrier by adopting an isovolumetric soaking method, and after standing for at least 2 hours at room temperature, the coconut carbon carrier is dried; and dissolving chloroplatinic acid and N-methylsuccinimide in deionized water, stirring and dissolving, then continuously stirring, immersing the obtained solution in the carrier by using an isovolumetric immersion method, standing at room temperature for at least 12h, drying and loading into a tubular furnace, heating and reducing for at least 3h under flowing hydrogen atmosphere, fully reducing metal components, cooling to room temperature, and then switching to flowing inert atmosphere and purging for at least 2h to obtain the required catalyst.

Example 1:

(1) Dissolving urea phosphate in water under a room temperature stirring state, then soaking the urea phosphate on a coconut carbon carrier, standing for 12 hours, thoroughly drying the urea phosphate at 100 ℃, then loading a sample into a tube furnace, heating to 800 ℃ under a flowing inert atmosphere and maintaining the temperature for 3 hours, and then cooling to room temperature under the flowing inert atmosphere to obtain a nitrogen-phosphorus modified coconut carbon carrier; wherein the dosage of urea phosphate accounts for 10 percent of the mass of the coconut shell carbon, the inert atmosphere is nitrogen, and the gas space velocity is 3000h ^-1 ；

(2) Dissolving potassium chloride in deionized water under the stirring state at 50 ℃, soaking the potassium chloride on a nitrogen-phosphorus modified coconut carbon carrier by adopting an equal volume soaking method after stirring and dissolving, standing for 2 hours at room temperature, and thoroughly drying the coconut carbon carrier at 80 ℃; dissolving chloroplatinic acid and N-methylsuccinimide in deionized water, stirring for dissolving, continuing stirring for 1h, soaking the obtained solution in the carrier by an isovolumetric soaking method, standing at room temperature for 12h, thoroughly drying at 80 ℃, loading a sample into a tubular furnace, heating to 400 ℃ under flowing hydrogen atmosphere, reducing for 3h, cooling to room temperature, switching to flowing nitrogen, and continuing to purge for at least 2h to obtain the required catalyst; wherein the dosage of chloroplatinic acid is 2% of the mass of the nitrogen-phosphorus modified coconut shell carbon carrier, the mol ratio of chloroplatinic acid to N-methyl succinimide is 1:2, the dosage of potassium chloride is 2% of the mass of the nitrogen-phosphorus modified coconut shell carbon carrier, and the gas space velocity of hydrogen is 1800h ^-1 The gas space velocity of nitrogen is 1800h ^-1 The method comprises the steps of carrying out a first treatment on the surface of the The catalyst obtained was numbered CAT#1.

Example 2:

the procedure of example 2 was the same as in example 1, except that urea phosphate was used in the amount of 10% by mass of the coconut shell charcoal in step (1) was replaced with 20%. The catalyst obtained was numbered CAT#2.

Example 3:

the procedure for the preparation of example 3 is the same as in example 1, except that N-methylsuccinimide in step (2) is replaced with N-ethylsuccinimide. The catalyst obtained was numbered CAT#3.

Example 4:

the procedure for the preparation of example 4 was the same as in example 1, except that N-methylsuccinimide in step (2) was replaced with succinimide. The catalyst obtained was numbered CAT#4.

Example 5:

the procedure of example 5 was the same as in example 1, except that the chloroplatinic acid was used in the amount of 2% by mass of the nitrogen-phosphorus-modified coconut shell carbon support in the step (2) was replaced with 5%. The catalyst obtained was numbered CAT#5.

Example 6:

the procedure of example 6 was the same as in example 1 except that the amount of potassium chloride used in step (2) was replaced with 3% by 2% based on the mass of the nitrogen-phosphorus-modified coconut shell charcoal carrier. The catalyst obtained was numbered CAT#6.

Example 7:

the procedure of example 7 was the same as in example 1 except that the molar ratio of chloroplatinic acid to N-methylsuccinimide in step (2) was changed to 1:3. The catalyst obtained was numbered CAT#7.

Comparative example 1:

the purpose was to compare with example 1 to illustrate the effect of urea phosphate modified coconut shell carbon on the resulting catalyst.

Dissolving potassium chloride in deionized water under the stirring state at 50 ℃, soaking the potassium chloride on a coconut shell carbon carrier by adopting an equal volume soaking method after stirring and dissolving, standing for 2 hours at room temperature, and thoroughly drying the coconut shell carbon carrier at 80 ℃; dissolving chloroplatinic acid and N-methylsuccinimide in deionized water, stirring for dissolving, continuing stirring for 1h, soaking the obtained solution in the carrier by an isovolumetric soaking method, standing at room temperature for 12h, thoroughly drying at 80 ℃, loading a sample into a tubular furnace, heating to 400 ℃ under flowing hydrogen atmosphere, reducing for 3h, cooling to room temperature, switching to flowing nitrogen, and continuing to purge for at least 2h to obtain the required catalyst; wherein the dosage of chloroplatinic acid accounts for 2% of the mass of the nitrogen-phosphorus modified coconut shell charcoal carrier, the mol ratio of the chloroplatinic acid to the N-methylsuccinimide is 1:2, and the chlorineThe dosage of potassium sulfide accounts for 2 percent of the mass of the nitrogen-phosphorus modified coconut shell carbon carrier, and the gas space velocity of hydrogen is 1800h ^-1 The gas space velocity of nitrogen is 1800h ^-1 The method comprises the steps of carrying out a first treatment on the surface of the The catalyst obtained was numbered CAT#8.

Comparative example 2:

the purpose was to compare with example 1 to illustrate the effect of lower temperature on the resulting catalyst during heat treatment.

The preparation procedure of comparative example 2 was the same as in example 1 except that 800℃in step (1) was replaced with 600 ℃. The catalyst obtained was numbered CAT#9.

Comparative example 3:

the purpose was to compare with example 1 to illustrate the effect of excessive temperature on the resulting catalyst during heat treatment.

The preparation procedure of comparative example 3 was the same as in example 1 except that 800℃in step (1) was replaced with 850 ℃. The catalyst obtained was numbered CAT#10.

Comparative example 4:

the purpose was to compare with example 1 to illustrate the necessity of urea phosphate as nitrogen and phosphorus double modified coconut charcoal.

The preparation procedure of comparative example 4 was the same as in example 1, except that urea phosphate in step (1) was replaced with urea. The catalyst obtained was numbered CAT#11.

Comparative example 5:

the purpose was to compare with example 1 to illustrate the necessity of urea phosphate as nitrogen and phosphorus double modified coconut charcoal.

The preparation procedure of comparative example 5 was the same as in example 1 except that urea phosphate in step (1) was replaced with diammonium phosphate. The catalyst obtained was numbered CAT#12.

Comparative example 6:

the purpose was to compare with example 1 to illustrate the necessity of stepwise impregnation with potassium chloride.

The preparation procedure of comparative example 6 was the same as in example 1 except that potassium chloride in step (2) was added to a solution of chloroplatinic acid and N-methylsuccinimide to impregnate them together. The catalyst obtained was numbered CAT#13.

Comparative example 7:

the purpose was to compare with example 1 to illustrate the necessity of addition of N-methylsuccinimide ligand.

The procedure of comparative example 7 was the same as in example 1, except that N-methylsuccinimide in step (2) was removed. The catalyst obtained was numbered CAT#14.

Comparative example 8:

the purpose was to illustrate the effect of a small amount of N-methylsuccinimide added on the catalyst, compared with example 1.

The procedure of comparative example 8 was the same as in example 1 except that the molar ratio of chloroplatinic acid to N-methylsuccinimide in step (2) was changed to 1:2.5. The catalyst obtained was numbered CAT#15.

Comparative example 9:

the purpose was to illustrate the effect of the addition of N-methylsuccinimide on the catalyst in comparison with example 1.

The procedure of comparative example 9 was the same as in example 1 except that the molar ratio of chloroplatinic acid to N-methylsuccinimide in step (2) was 1:2 and was replaced with 1:3. The catalyst obtained was numbered CAT#16.

Comparative example 10:

the purpose was to illustrate the effect of a small amount of potassium chloride added on the catalyst, compared with example 1.

Comparative example 10 was prepared in the same manner as in example 1 except that the amount of potassium chloride used in step (2) was replaced with 1.5% based on 2% by mass of the nitrogen-phosphorus-modified coconut shell charcoal carrier. The catalyst obtained was numbered CAT#17.

Comparative example 11:

the purpose was to illustrate the effect of potassium chloride addition on the catalyst in comparison with example 1.

The procedure of comparative example 11 was the same as in example 1 except that the amount of potassium chloride used in step (2) was replaced with 3.5% by 2% of the mass of the nitrogen-phosphorus-modified coconut shell charcoal carrier. The catalyst obtained was numbered CAT#18.

Performance test of catalyst for CO selective catalytic oxidation experiments under hydrogen rich conditions:

(1) Grinding the catalyst and sieving to obtain small particles with the particle diameter in the range of 1/15-1/20 of the inner diameter of the fixed bed reaction tube;

(2) Loading the sieved catalyst particles into a constant temperature zone of a constant pressure fixed bed reactor, and adding active carbon or quartz sand on the upper layer of the catalyst as a gas preheating layer;

(3) In the flowing 5% O ₂ /N ₂ The catalyst was warmed to 85℃under a mixed gas atmosphere and then 1% CO/H was introduced ₂ The mixed gas starts to react; wherein 1% CO/H ₂ The gas space velocity of the mixed gas is 3000h ^-1 Regulating 5% O ₂ /N ₂ The flow rate of the mixed gas is used for maintaining the ratio of CO to O ₂ The volume ratio of (2) is 1:0.8;

(4) The concentration change before and after the CO reaction was detected by using a gas chromatograph equipped with a methane reformer and FID detection.

The CO content in the mixed gas before the reaction is 1%, and the CO content in the tail gas after the reaction of different catalysts is shown in table 1, wherein most of the CO content can reach PPM level or below, so that the catalyst provided by the method shows excellent CO catalytic oxidation activity.

TABLE 1 CO content in the tail gas after reaction with different catalysts

Catalyst numbering	CO content (ppm)	Catalyst numbering	CO content (ppm)
				CAT#1	0.024	CAT#10	1.753
CAT#2	0.013	CAT#11	14.003
				CAT#3	0.023	CAT#12	15.212
CAT#4	0.027	CAT#13	7.394
				CAT#5	0	CAT#14	440.324
CAT#6	0.008	CAT#15	0.944
				CAT#7	0.004	CAT#16	0.693
CAT#8	8.245	CAT#17	2.141
				CAT#9	2.132	CAT#18	2.930

The catalyst stability and the CO selectivity of the catalytic reaction were tested for the CAT #5 catalyst, and the results are shown in FIG. 2. The result shows that the conversion rate of CO is still 100% after 180 hours of continuous catalytic reaction, which indicates that the catalyst has good catalytic stability. At the same time, the area of the hydrogen peak in the product is not reduced, which proves that the catalyst can preferentially oxidize CO into CO under the hydrogen-rich condition ₂ I.e. a high selectivity of the catalytic oxidation of CO is achieved.

According to the invention, urea phosphate is used for carrying out nitrogen-phosphorus double modification on the coconut shell carbon carrier, so that the content of nitrogen and phosphorus sites in the carrier is increased, the number of metal anchoring sites is increased, and the catalytic activity is improved; the electronic auxiliary agent potassium chloride is used, and the potassium chloride and the chloroplatinic acid are subjected to a step-by-step impregnation method, so that the potassium chloride and the chloroplatinic acid solution are prevented from slowly reacting; the dicarbonyl ligand N-methyl succinimide, N-ethyl succinimide or succinimide is used to stabilize and disperse the platinum ions. The three dicarbonyl ligands can act as soft templates, improving the dispersibility of platinum, and the stability and the catalytic selectivity of the catalyst.

The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made therein without departing from the spirit and scope of the invention, which is defined by the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (9)

1. A preparation method of a catalyst for deep removal of carbon monoxide under a hydrogen-rich condition is characterized by comprising the following steps of: the method comprises the following steps:

step 1: under the stirring state at room temperature, dissolving urea phosphate in water, then dipping the urea phosphate on a coconut carbon carrier, standing, drying, loading the coconut carbon carrier into a tube furnace, heating up and maintaining for at least 3 hours under flowing inert atmosphere, and then cooling to room temperature to obtain a nitrogen-phosphorus modified coconut carbon carrier;

step 2: under a certain temperature stirring state, potassium chloride is dissolved in deionized water, after stirring and dissolution, the potassium chloride is soaked on a nitrogen-phosphorus modified coconut carbon carrier by adopting an isovolumetric soaking method, and after standing for at least 2 hours at room temperature, the coconut carbon carrier is dried; and dissolving chloroplatinic acid and N-methylsuccinimide in deionized water, stirring and dissolving, then continuously stirring, immersing the obtained solution in the carrier by using an isovolumetric immersion method, standing at room temperature for at least 12h, drying and loading into a tubular furnace, heating and reducing for at least 3h under flowing hydrogen atmosphere, cooling to room temperature, and then switching to flowing inert atmosphere and purging for at least 2h to obtain the required catalyst.

2. The method for preparing the catalyst for deep removal of carbon monoxide under hydrogen-rich conditions according to claim 1, wherein the method comprises the following steps: the step 1 further comprises the following steps: dissolving urea phosphate in water, soaking the urea phosphate on a coconut shell carbon carrier, standing for at least 12 hours, thoroughly drying the urea phosphate at 100-150 ℃, then loading a sample into a tube furnace, heating to 650-800 ℃ under flowing inert atmosphere and maintaining the temperature for at least 3 hours, and then cooling to room temperature under flowing inert atmosphere to obtain a nitrogen-phosphorus modified coconut shell carbon carrier; wherein the dosage of the urea phosphate accounts for 10-20% of the mass of the coconut shell carbon, the inert atmosphere is one or more of nitrogen, argon and helium, and the gas airspeed of the inert atmosphere is 3000-12000h ^-1 。

3. The method for preparing the catalyst for deep removal of carbon monoxide under hydrogen-rich conditions according to claim 1, wherein the method comprises the following steps: the step 2 further comprises the following steps: dissolving potassium chloride in deionized water under stirring at 50-60deg.C, soaking in nitrogen by isovolumetric soaking methodStanding the phosphorus-modified coconut shell carbon carrier for at least 2 hours at room temperature, and thoroughly drying the phosphorus-modified coconut shell carbon carrier at 80-95 ℃; dissolving chloroplatinic acid and N-methylsuccinimide in deionized water, stirring for dissolving, continuing stirring for at least 1h, soaking the obtained solution in the carrier by an isovolumetric soaking method, standing at room temperature for at least 12h, thoroughly drying at 80-95 ℃, loading a sample into a tubular furnace, heating to 400-450 ℃ under flowing hydrogen atmosphere, reducing for at least 3h, cooling to room temperature, switching to flowing inert atmosphere, and continuing to purge for at least 2h to obtain the required catalyst; wherein the dosage of chloroplatinic acid accounts for 2-5% of the mass of the nitrogen-phosphorus modified coconut carbon carrier, the mol ratio of the chloroplatinic acid to the N-methyl succinimide is 1:2-1:3, the dosage of potassium chloride accounts for 2-3% of the mass of the nitrogen-phosphorus modified coconut carbon carrier, and the gas space velocity of hydrogen is 1800-9600h ^-1 The gas space velocity of the inert atmosphere is 1800-9600h ^-1 。

4. The method for preparing the catalyst for deep removal of carbon monoxide under hydrogen-rich conditions according to claim 3, wherein the method comprises the following steps: replacing N-methyl succinimide with N-ethyl succinimide; the molar ratio of chloroplatinic acid to N-ethylsuccinimide is 1:2-1:3.

5. The method for preparing the catalyst for deep removal of carbon monoxide under hydrogen-rich conditions according to claim 3, wherein the method comprises the following steps: n-methyl succinimide is replaced by succinimide, and the molar ratio of chloroplatinic acid to the succinimide is 1:2-1:3.

6. The method for preparing the catalyst for deep removal of carbon monoxide under hydrogen-rich conditions according to claim 1, wherein the method comprises the following steps: the specific surface area of the coconut shell carbon is more than 1000m ² /g。

7. The method for preparing the catalyst for deep removal of carbon monoxide under hydrogen-rich conditions according to claim 1, wherein the method comprises the following steps: the step-by-step impregnation method is as follows: first impregnating potassium chlorideOn the nitrogen-phosphorus modified coconut shell carbon carrier, drying and then carrying out secondary impregnation to upload platinum species, so that the dispersibility of the platinum species is not affected; at the same time, potassium ions can be combined with carbonyl groups on the surface of the coconut shell carbon carrier preferentially, and the K has lower electronegativity, so that the electronic auxiliary agent K ⁺ The electron offset to the oxygen atoms can be generated through the Pt-O-K form, so that the electron offset degree of Pt to the oxygen atoms is weakened, and the Pt atoms on the surfaces of the nano particles are more close to a low valence state.

8. A catalyst for deep removal of carbon monoxide under hydrogen-rich conditions is characterized in that: obtained using the preparation method according to any one of the preceding claims 1 to 7.

9. A method of using a catalyst prepared by the method of any one of claims 1 to 7; the method is characterized by comprising the following steps of:

(1) Grinding the catalyst and sieving to obtain small particles with the particle diameter in the range of 1/15-1/20 of the inner diameter of the fixed bed reaction tube;

(2) Loading the sieved catalyst particles into a constant temperature zone of a constant pressure fixed bed reactor, and adding active carbon or quartz sand on the upper layer of the catalyst as a gas preheating layer;

(3) In the flowing 5% O ₂ /N ₂ Heating the catalyst to 75-95 ℃ under the atmosphere of mixed gas, and then introducing 1% CO/H ₂ The mixed gas starts to react; wherein 1% CO/H ₂ The gas space velocity of the mixed gas is 1500-6000h ^-1 By adjusting 5% O ₂ /N ₂ The flow rate of the mixed gas is used for maintaining the ratio of CO to O ₂ The volume ratio of (2) is 1:0.6-1:0.8;

(4) The concentration change before and after the CO reaction was detected by using a gas chromatograph equipped with a methane reformer and FID detection.

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