CN115528262A - Microorganism-sodium alginate-based porous composite palladium-carbon catalyst and preparation method thereof - Google Patents

Microorganism-sodium alginate-based porous composite palladium-carbon catalyst and preparation method thereof Download PDF

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CN115528262A
CN115528262A CN202211202308.5A CN202211202308A CN115528262A CN 115528262 A CN115528262 A CN 115528262A CN 202211202308 A CN202211202308 A CN 202211202308A CN 115528262 A CN115528262 A CN 115528262A
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palladium
sodium alginate
microorganism
gel microspheres
porous composite
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梁伊丽
刘锋
黄静雯
李诗卉
刘学端
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Central South University
Sino Platinum Metals Co Ltd
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Sino Platinum Metals Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
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    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
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Abstract

The invention discloses a microorganism-sodium alginate-based porous composite palladium-carbon catalyst and a preparation method thereof, belonging to the technical field of fuel cells. Adding the solution containing calcium ions into a mixed solution containing sodium alginate, calcium carbonate and microorganisms to perform a crosslinking reaction to form composite gel microspheres; leaching the composite gel microspheres in an acid solution to obtain porous composite gel microspheres; placing the porous composite gel microspheres in water, and adding a palladium source for adsorption; obtaining palladium-loaded composite gel microspheres; the palladium-loaded composite gel microspheres are subjected to freeze drying, carbonization and reduction roasting in sequence to obtain the microorganism-sodium alginate-based porous composite palladium-carbon catalyst which has a porous structure, is good in stability, has high nano-palladium loading amount, is uniformly distributed, shows high catalytic activity and can be applied to fuel cells.

Description

Microorganism-sodium alginate-based porous composite palladium-carbon catalyst and preparation method thereof
Technical Field
The invention relates to an electrochemical catalytic material, in particular to a microorganism-sodium alginate-based porous composite palladium-carbon catalyst, and also relates to a preparation method thereof, belonging to the technical field of fuel cells.
Background
With the increasing decrease of fossil energy and the global energy crisis, the development of new, efficient, wide-range and environment-friendly power supply devices is urgent. Proton Exchange Membrane Fuel Cells (PEMFCs) have the advantages of environmental protection, high energy density, high energy conversion rate, and the like, and meet the requirements for energy in the future, and therefore, are one of the most potential future cells; however, the proton exchange membrane fuel cell has the disadvantages of high catalyst cost, complex bipolar plate process, high manufacturing cost of the diffusion layer and the like, so that the progress of the proton exchange membrane fuel cell on the commercialized and practical roads is slow.
As one of the important constituent structures of the PEMFC, a catalyst catalyzes the formation of protons from hydrogen at the anode and the reduction of oxygen at the cathode to generate oxygen ions, and the oxygen ions combine with the hydrogen protons to generate water to generate energy. The noble metals platinum (Pt) and palladium (Pd) are the common and ideal catalyst materials, but the reserves of the catalyst materials are limited all over the world, so that the development of a low-cost, high-activity and high-stability catalyst is a problem to be solved urgently by the current proton exchange membrane fuel cell.
Compared with a physical method and a chemical method, the microbial synthesis metal nano-catalyst in the existing method for preparing the fuel cell catalyst has incomparable advantages which are mainly shown in that: (1) inheritance: obtaining a porous heteroatom-doped catalyst carbon carrier through a biological genetic effect; (2) self-assembly: a multi-component, layered functional material can be spontaneously assembled; (3) high dispersibility: the hydrophilicity of the microorganism is excellent, and the highly dispersed nano catalyst material can be synthesized in situ by taking the microorganism as a template; (4) green environmental protection: no extra dispersant is needed, and the surface of the synthesized nano material is clean; (5) compatibility: the method is easy to combine with a chemical synthesis method, and can be used for synergistically constructing the distribution of components, structures and the like of the catalyst, thereby improving the designability of the material. However, the existing process for synthesizing nano-metal material by using microorganisms has the defects of unstable particle size, low adsorption quantity, low specific surface area and the like, for example, the particle size of biological nano-metal is usually in the range of 1-50 nm, and the ratio of catalyst noble metal is about 10%. Shewanella (Shewanella) is widely distributed in natural environments such as fresh water, sea and sediments, has excellent capability of depositing metal nanoparticles, and is a typical dissimilatory metal-reducing bacterium. At present, different Shewanella strains (such as MR-1, CN-32 and W-3181), hydrogen reduction process, microorganism-different carbon material composite matrixes, different cells and extracellular components, hydrogenase/reductase and the like are researched and discussed to influence in the synthesis of metal nano materials, and the size of nano metal can be adjusted within 10nm by controlling the technical conditions, so that the uniform distribution of the nano metal is realized. Although some of the adjustment means and mechanisms have been elucidated, the implementation is still somewhat difficult and not suitable for large-scale production.
Disclosure of Invention
Aiming at the technical problems of insufficient metal adsorption amount, difficult regulation and control of distribution and the like in the process of synthesizing metal nano materials by the conventional biological method, the invention aims to provide a microorganism-sodium alginate-based porous composite palladium-carbon catalyst, which has a porous structure, good stability, high nano-palladium loading amount, uniform distribution and high catalytic activity.
The second purpose of the invention is to provide a preparation method of the microorganism-sodium alginate-based porous composite palladium-carbon catalyst, which has the advantages of simple operation, easily obtained raw materials, low cost and contribution to expanded production.
In order to realize the technical purpose, the invention provides a preparation method of a microorganism-sodium alginate-based porous composite palladium-carbon catalyst, which comprises the following steps:
1) Adding a mixed solution containing sodium alginate, calcium carbonate and microorganisms into a solution of calcium ions for crosslinking reaction to form composite gel microspheres;
2) Leaching the composite gel microspheres in an acid solution to obtain porous composite gel microspheres;
3) Placing the porous composite gel microspheres in water, and adding a palladium source for adsorption; obtaining palladium-loaded composite gel microspheres;
4) And (3) sequentially carrying out freeze drying, carbonization and reduction roasting on the palladium-loaded composite gel microspheres to obtain the palladium-loaded composite gel microspheres.
The technical scheme of the invention adopts a co-embedding technology to construct a carrier of a catalytic material, mainly utilizes sodium alginate to form gel microspheres under the crosslinking action of calcium ions, and embeds microorganisms in the gel microspheres, more specifically, sodium alginate provides stable framework support for the gel microspheres after crosslinking, and the embedded microorganisms are stably and dispersedly filled in the framework of the gel microspheres and are not easy to lose, sodium alginate and microorganisms fully utilize relatively rich oxygen-containing functional groups to play a role in strengthening a palladium source in an adsorption solution system, so that the adsorption efficiency and the adsorption capacity of the palladium source are greatly improved, the dispersibility of the palladium source can be improved, the agglomeration is avoided, and the subsequent obtaining of nano metal palladium particles is facilitated. On the basis, the technical scheme of the invention further adopts a template pore-forming technology, calcium carbonate is used as a pore-forming template to form abundant pores in the gel microsphere, so that a connecting channel between the interior of the gel microsphere and an external medium can be increased, the adsorption sites of the palladium source in the interior are better exposed, more active sites can be provided to combine with the palladium source, and the diffusion of the palladium source to the interior of the gel microsphere and the uniform distribution of the palladium source in the interior of the gel microsphere are facilitated. According to the technical scheme, the gel microspheres adsorbing the palladium source are carbonized and reduced, the gel microspheres form a stable porous structure carrier, and the nano metal palladium is generated on the surface and in pores of the carrier in situ, so that stable and dispersed loading is realized, the particle size is more uniform and smaller, and the whole catalytic material has high catalytic activity.
As a preferable scheme, the mass percent concentration of the sodium alginate in the mixed solution containing the sodium alginate, the calcium carbonate and the microorganism is 1.5 to 2.5 percent, the mass percent concentration of the calcium carbonate is 1 to 2 percent, and the content of the microorganism is 60 to 80L OD in each liter of the mixed solution 600 Mass measurement of microorganisms collected in culture medium of =1.0 to 1.2. Calcium carbonate is used as a pore-forming template, and the content of the calcium carbonateIf the ratio of calcium carbonate is too high, the stability of the porous carrier formed after the gel microspheres are carbonized can be affected. When the ratio of sodium alginate to microorganisms is too low, the microorganisms are difficult to fully embed, and when the ratio of sodium alginate to microorganisms is too high, the microorganisms filled in the gel microspheres are few, so that the adsorption quantity and the dispersibility of the palladium source are difficult to improve.
In a preferred embodiment, the concentration of calcium ions in the solution containing calcium ions is 1 to 3mol/L. The solution containing calcium ions mainly utilizes calcium ions to perform ion exchange on sodium alginate so as to realize crosslinking. The calcium ion-containing solution is provided by a water-soluble calcium salt, more specifically calcium chloride, calcium nitrate, and the like.
As a preferable scheme, the volume ratio of the solution containing calcium ions to the mixed solution containing sodium alginate, calcium carbonate and microorganisms is 3. Too low proportion of the solution containing calcium ions can reduce the crosslinking degree of sodium alginate, and can not form stable gel microspheres, and if the proportion of calcium ions is too high, the solution can occupy partial adsorption active sites, and the adsorption capacity of the gel microspheres is reduced.
As a preferred embodiment, the microorganism is shewanella. A more specific microorganism is the Shewanella onedenss MR-1 strain (purchased from American type culture Collection under the trade designation ATCC 700550). The preferred Shewanella has good adsorption effect on palladium source, is rich in hydrogenase, has high tolerance to noble metal, and is resistant to Pd 2+ Has excellent adsorption capacity and certain reduction capacity on metal ions under certain conditions, so that the aim of well depositing metal nano particles can be fulfilled by using Shewanella, and the Shewanella is selected to perform Pd treatment 2+ The adsorption characteristic and the subsequent carbonization process can synthesize the carbonized bacteria supported noble metal catalyst with good stability and high catalytic activity, and the carbon material obtained after carbonization has the nitrogen doping effect, so that the supported stability of palladium can be improved, and the catalytic activity of palladium can be synergistically improved. Shewanella can well adsorb palladium ionsAnd the palladium ions can be uniformly and stably loaded in the Shewanella carbomorpha after carbonization.
As a preferred scheme, the leaching conditions are as follows: adopting hydrochloric acid solution with the concentration of 0.1-0.3 mol/L to leach for 15-30 min at room temperature. The calcium carbonate template agent can be decomposed and removed by adopting diluted acid with proper concentration, the structure of the gel microspheres can not be damaged, the calcium carbonate is difficult to be efficiently removed when the concentration is too low, and the gel microspheres are easy to damage when the concentration is too high.
As a preferred scheme, the palladium source is sodium tetrachloropalladate; the palladium source is added in the form of solution with the concentration of 6-8 mmol/L.
As a preferred scheme, the carbonization and reduction roasting process comprises the following steps: the carbonization and reduction roasting processes are as follows: firstly, under the protective atmosphere, the temperature is raised to 750-850 ℃ at the speed of 3-4 ℃/min, the temperature is preserved for 2.5-3.5 h, then the temperature is lowered to 180-220 ℃, and the temperature is preserved for 1.5-2.5 h under the reducing atmosphere. A reducing atmosphere such as hydrogen. At the optimal carbonization temperature, the full carbonization of organic matters and the decomposition of the palladium source can be realized, if the temperature is too high, the porous structure of the carbonized material is easy to damage, and metal aggregation is easy to cause, and if the temperature is too low, the carbonization and the decomposition of the palladium source are incomplete.
The invention also provides a microorganism-sodium alginate-based porous composite palladium-carbon catalyst, which is obtained by the preparation method.
The microorganism-sodium alginate-based porous composite palladium-carbon catalyst takes a porous carbon material as a carrier, and nano metal palladium particles are uniformly dispersed and loaded on the surface and in pore channels of the carrier. The average particle diameter of the nano metal palladium particles is about 7nm, and the particles are uniformly distributed.
Compared with the prior art, the technical scheme of the invention has the following advantages and beneficial effects:
in the preparation process of the microorganism-sodium alginate-based porous composite palladium-carbon catalyst, a co-embedding technology is adopted to construct a carrier of a catalytic material, sodium alginate is utilized to form gel microspheres under the cross-linking action of calcium ions, microorganisms are stably and dispersedly filled in the skeleton of the gel microspheres and are not easy to lose, the sodium alginate and oxygen-containing functional groups relatively rich in microorganisms are utilized to strengthen a palladium source in an adsorption solution system, the adsorption efficiency and the adsorption capacity of the palladium source are greatly improved, the dispersibility of the palladium source can be improved, the agglomeration is avoided, and the subsequent obtaining of nano metal palladium particles is facilitated.
The preparation process of the microorganism-sodium alginate-based porous composite palladium-carbon catalyst adopts a template pore-forming technology, calcium carbonate is used as a pore-forming template to form abundant pores in the gel microsphere, so that a connecting channel between the interior of the gel microsphere and an external medium can be increased, an internal palladium source adsorption site is better exposed, more active sites can be provided to combine with a palladium source, and the diffusion of the palladium source to the interior of the gel microsphere and the uniform distribution of the palladium source in the interior of the gel microsphere are better facilitated.
In the preparation process of the microorganism-sodium alginate-based porous composite palladium-carbon catalyst, calcium carbonate templates are used for pore forming and sodium alginate is used for crosslinking to form porous gel microspheres, the porous gel microspheres are further carbonized to form a stable porous structure carrier, microorganisms adsorbing a palladium source are embedded and filled in the gel microspheres, highly dispersed nano metal palladium with uniform particle size is formed in situ through carbonization and reduction, and the nano metal palladium is loaded on the surface and in pores of the carrier, so that the integral catalytic material shows high catalytic activity.
The preparation method of the microorganism-sodium alginate-based porous composite palladium-carbon catalyst is simple to operate, easily available in raw materials and low in cost, and is favorable for expanded production.
The microorganism-sodium alginate-based porous composite palladium-carbon catalyst has a porous structure, a large specific surface area, small palladium nanoparticle particle size and narrow distribution (the average particle size is about 7 nanometers), is uniformly and stably loaded in a carrier, and improves the comprehensive performance of a catalytic material.
Drawings
FIG. 1 is a diagram of the Shewanella-sodium alginate-based porous composite gel microspheres before and after palladium adsorption in example 1; the left picture is gel microspheres formed by co-embedding Shewanella and sodium alginate, and the right picture is after the co-embedding gel microspheres complete Pd adsorption.
FIG. 2 isTransmission Electron Microscopy (TEM) and particle size distribution plots of the samples treated differently in example 1, wherein a and b are Shewanella-based palladium on carbon catalysts (Pd/MR 1), c and d are Shewanella-sodium alginate-based palladium on carbon catalysts (Pd/MR 1-SA), and e and f are Shewanella-sodium alginate-calcium carbonate-based palladium on carbon catalysts (Pd/MR 1-SA-CaCO) 3 )。
FIG. 3 shows Shewanella-sodium alginate-calcium carbonate pore-forming palladium-carbon catalyst (Pd/MR 1-SA-CaCO) at different magnifications and scales in example 1 3 ) A TEM image of (a).
FIG. 4 shows the results of electrochemical testing of different treated samples of example 1; in the figure, a and b are Shewanella-based palladium-carbon catalysts (Pd/MR 1), c and d are Shewanella-sodium alginate-based palladium-carbon catalysts (Pd/MR 1-SA), and e and f are Shewanella-sodium alginate-calcium carbonate pore-forming palladium-carbon catalysts (Pd/MR 1-SA-CaCO) 3 )。
Detailed Description
The following specific examples are intended to further illustrate the present disclosure, but not to limit the scope of the claims.
In the following examples, the chemical starting materials are conventional commercial products unless otherwise specified. The calcium carbonate powder is analytically pure calcium carbonate of national medicine group chemical reagent limited company, and the product model is 10005760.
Example 1
1) Activation and propagation of microbial strains: the microorganism used was Shewanella onedenss MR-1. During activation, the bacteria are taken out from a refrigerator at the temperature of-80 ℃, streaked on an LB solid culture medium, and then cultured for 20 hours at the constant temperature of 30 ℃. Inoculating the cultured single colony in 100mL LB culture medium, shake culturing at 170rpm and 30 deg.C for 18h, inoculating the activated bacterial liquid in 1500mL LB liquid culture medium according to 2% inoculum size, shake culturing at 170rpm and 30 deg.C for 15h, measuring OD 600 =1.1. The bacteria after the expanded culture were collected by centrifugation, and the centrifugation parameters were set to 8000rpm,8min.
2) Preparing the composite gel microspheres: preparing a mixed solution containing 2% of sodium alginate and 1.5% of calcium carbonate powder 25ml, adding the thallus collected in the previous step into the prepared mixed solution to be fully and uniformly mixed, and then mixingDripping into CaCl at 2mol/L 2 In solution (100 ml) gel microspheres were formed by crosslinking.
3) Calcium carbonate pore-forming: after the gel microspheres are stabilized, the gel microspheres are fished out and placed in 0.2mol/L HCl solution for reaction for 20min, and the phenomenon that the gel microspheres float upwards can be seen, which indicates that the pore-forming is successful.
4) Palladium ion adsorption: respectively placing the collected thalli, the composite gel microspheres (without calcium carbonate) and the calcium carbonate pore-formed composite gel microspheres in 25mL of deionized water, preparing 75mL of 6.89mmol/L sodium tetrachloropalladate solution, adjusting the pH to 3 with hydrochloric acid, dropwise adding the sodium tetrachloropalladate solution into the collected thalli, the composite gel microspheres and the calcium carbonate pore-formed composite gel microspheres by using a peristaltic pump, fully stirring and adsorbing by using a magnetic stirrer, wherein the dropping speed of the peristaltic pump is 0.5mL/min, the rotating speed of the magnetic stirring is 400rpm, and the reaction time is 24 hours.
5) Freeze drying, high temperature reduction and carbonization, freezing the thallus for adsorbing palladium, the composite gel microspheres and the calcium carbonate pore-formed composite gel microspheres in a refrigerator at-80 ℃ overnight, and then carrying out freeze drying by using a vacuum freeze dryer to carry out the next carbonization and reduction. Performing carbonization reduction in a tube furnace, introducing argon, heating at a speed of 3 ℃/min to raise the temperature of the tube furnace to 800 ℃, preserving heat for 3 hours, then introducing hydrogen when the temperature is reduced to 200 ℃, preserving heat for 2 hours, closing the hydrogen, taking out a sample when the temperature of the tube furnace is reduced to room temperature, and respectively obtaining a Shewanella-based palladium-carbon catalyst (Pd/MR 1), a Shewanella-sodium alginate-based palladium-carbon catalyst (Pd/MR 1-SA), and a Shewanella-sodium alginate-calcium carbonate pore-forming palladium-carbon catalyst (Pd/MR 1-SA-CaCO) 3 )。
FIG. 2 is a Transmission Electron Microscope (TEM) and particle size statistics of different treated samples. In the figure, a and b are Pd/MR1, c and d are Pd/MR1-SA, and e and f are Pd/MR1-SA-CaCO 3 . According to TEM images, the Pd/MR1 catalyst has obvious metal agglomeration and the worst uniformity, pd/MR1-SA and Pd/MR1-SA-CaCO 3 The palladium particles of (A) are well dispersed and can be seen through CaCO by naked eye observation 3 Pd/MR1-SA-CaCO after pore-forming 3 The palladium nano particles of the catalyst sample are distributed more finely and uniformly, and analysis software is used for counting and displaying three groupsThe average particle sizes were 15.97nm,11.26nm and 6.99nm, which are substantially consistent with TEM observations, and it is also generally presumed that pore-forming contributes to particle distribution and thus to catalyst performance.
FIG. 3 is Pd/MR1-SA-CaCO at different magnifications and scales 3 TEM image of Shewanella composite gel microsphere via CaCO 3 After pore forming, the distribution of palladium particles is improved, and a series of light-colored circular pore-shaped structures can be observed after TEM image magnification observation, which indicates CaCO 3 The pore-forming of the catalytic material is successful, and the final catalyst presents a predicted porous structure, pd/MR1-SA-CaCO 3 Can also benefit from the porous structure, thereby increasing the connecting channel between the interior of the gel ball and the external medium, leading the adsorption sites in the interior to be better exposed to the external adsorbate and leading the distribution of the palladium to be more uniform.
And (3) testing the catalytic performance:
1) Preparation of catalyst ink:
weighing palladium carbon catalyst 4mg, adding 200 microliter ethanol, slightly shaking, sequentially adding 760 microliter distilled water and 40 microliter Nafion (5% by weight), and performing ultrasonic treatment for 30min.
2) Cleaning a working electrode and spotting and drying:
and polishing and cleaning the working electrode by using 0.05 micron polishing powder, sucking 15 microliters of prepared catalyst ink by using a liquid transfer gun after the electrode is dried, dropwise adding the catalyst ink into a glassy carbon electrode dropping area, and then waiting for the sample to be completely dried.
3) Preparing electrochemical detection:
adding a proper amount of 0.1M KOH electrolyte which is prepared in situ into the electrolyte container, and introducing oxygen for 30min to form oxygen saturated electrolyte. Before the formal test, the working electrode is activated, namely, the sweep of 20 circles is carried out by a voltammetry cyclic method at the sweep rate of 0.05V/s within the test voltage range. And after the working electrode is fully activated, carrying out voltammetry cyclic detection and linear scanning voltammetry detection.
Voltammetric cycling: voltage range-1V-0.2V, scanning rate: 0.01V/s
Linear sweep voltammetry: voltage range-0.8V-0.4V, scanning rate: 0.01V/s
4) Catalytic activity index calculation
The Electrochemical activity index calculation mainly includes Mass Activity (MA) and Specific surface area activity (SA) of the catalyst, and the formula is as follows:
ECSA＝Q/(424×Pd load )；
1/j＝1/j d +1/j k ；
MA＝j k /Pd load ；
SA＝MA/ECSA；
where Q represents the integrated area of the oxygen reduction peak and j represents the instantaneous current at a voltage of 0.1V at 1600 rpm. j is a unit of a group d Is the limiting current. Pd load The load of palladium is calculated according to the ICP detection result.
FIG. 4 shows the results of electrochemical measurements on three groups of treated samples, in which (a, b) are Shewanella-based palladium-on-carbon catalyst (Pd/MR 1), in which (c, d) Shewanella-sodium alginate-based palladium-on-carbon catalyst (Pd/MR 1-SA), and in which (e, f) is Shewanella-sodium alginate-calcium carbonate-pore-forming palladium-on-carbon catalyst (Pd/MR 1-SA-CaCO) 3 )。
Table 1 summarizes the main activity indexes of the test results, as shown by Pd/MR1-SA-CaCO 3 Compared with the other two groups with higher ECSA and MA, the total weight reaches 32.32m 2 ·g- 1 And 53.77A. G- 1 ECSA represents the electrochemical active area, and for some nanomaterials, a larger surface area can expose richer active sites, thus improving the electrochemical performance; MA is largely dependent on the size of the electrocatalyst particles, with smaller sized catalysts exhibiting higher mass activity because the smaller sized particles have a larger ratio of surface atoms to total atoms per unit mass and have a larger number of electrocatalytically active sites. Therefore, the electrochemical result is basically consistent with the characterization result in the embodiment 1, and the surface area and the metal distribution of the catalyst after pore-forming treatment are improved, so that better performance of catalysis is facilitated.
TABLE 1 electrochemical test Activity index parameter calculation results
Figure BDA0003872895170000081
Example 2
The sodium alginate concentration in step 2) in example 1 was set to 1.5%, the calcium carbonate powder concentration was set to 1.5%, and the other conditions were the same as in example 1.
Prepared Pd/MR1-SA-CaCO 3 The average particle size of the medium palladium nanoparticles is 8.89nm, and the ECSA, MA and SA of the medium palladium nanoparticles are 28.67m 2 ·g -1 ，43.25A·g -1 And 1.63 A.m -2 。
Example 3
The sodium alginate concentration in step 2) in example 1 was set to 2.5%, the calcium carbonate powder concentration was set to 1.5%, and the other conditions were the same as in example 1.
Prepared Pd/MR1-SA-CaCO 3 The average particle size of the medium palladium nanoparticles is 7.45nm, and the ECSA, MA and SA of the medium palladium nanoparticles are 30.78m 2 ·g -1 ，47.68A·g -1 And 1.67A · m -2 The uniformity and catalytic performance of the palladium nanoparticles under the treatment conditions are slightly lower than those of the samples treated in the embodiment 1 and slightly higher than those of the samples treated in the embodiment 2. Therefore, under the condition of keeping certain calcium carbonate concentration, the proper sodium alginate content can improve the performance of the catalyst, and when the content is too low or too high, the agglomeration of metal particles can be aggravated, so that the activity of the catalyst is influenced.
Example 4
The sodium alginate concentration in step 2) in example 1 was set to 2%, the calcium carbonate concentration was set to 2%, and the remaining conditions were the same as in example 1.
Prepared Pd/MR1-SA-CaCO 3 Has an average particle size of 7.61nm and an ECSA, MA and SA of 31.06m, respectively 2 ·g -1 ，48.35A·g -1 And 1.72 A.m -2 The metal uniformity and catalytic performance under the treatment condition are similar to those of the embodiment 3, and are slightly lower than the treatment sample of the embodiment 1 and higher than the embodimentExample 2 samples were processed. It follows that, under the conditions of optimum sodium alginate content in the above case, the production of a porous environment by continuing to increase the calcium carbonate concentration is not suitable for the preparation of the catalyst, probably because the metal particles are less fixed due to the excessive porous structure, thereby increasing the agglomeration.

Claims (9)

1. A preparation method of a microorganism-sodium alginate-based porous composite palladium-carbon catalyst is characterized by comprising the following steps: the method comprises the following steps:
1) Adding the solution containing calcium ions into a mixed solution containing sodium alginate, calcium carbonate and microorganisms to perform a crosslinking reaction to form composite gel microspheres;
2) Leaching the composite gel microspheres in an acid solution to obtain porous composite gel microspheres;
3) Placing the porous composite gel microspheres in water, and adding a palladium source for adsorption; obtaining palladium-loaded composite gel microspheres;
4) And (3) sequentially carrying out freeze drying, carbonization and reduction roasting on the palladium-loaded composite gel microspheres to obtain the palladium-loaded composite gel microspheres.
2. The preparation method of the microorganism-sodium alginate-based porous composite palladium-carbon catalyst according to claim 1, which is characterized in that: the mass percentage concentration of the sodium alginate in the mixed solution containing the sodium alginate, the calcium carbonate and the microorganism is 1.5 to 2.5 percent, the mass percentage concentration of the calcium carbonate is 1 to 2 percent, and the content of the microorganism is 60 to 80L OD in each liter of the mixed solution 600 Mass measurement of microorganisms collected in culture medium of =1.0 to 1.2.
3. The preparation method of the microorganism-sodium alginate-based porous composite palladium-carbon catalyst according to claim 1, which is characterized in that: the concentration of calcium ions in the solution containing calcium ions is 1 to 3mol/L.
4. The preparation method of the microorganism-sodium alginate-based porous composite palladium-carbon catalyst according to any one of claims 1 to 3, which is characterized in that: the volume ratio of the solution containing calcium ions to the mixed solution containing sodium alginate, calcium carbonate and microorganisms is 3.
5. The preparation method of the microorganism-sodium alginate-based porous composite palladium-carbon catalyst according to claim 4, characterized in that: the microorganism is Shewanella.
6. The preparation method of the microorganism-sodium alginate-based porous composite palladium-carbon catalyst according to claim 1, which is characterized in that: the leaching conditions are as follows: adopting hydrochloric acid solution with the concentration of 0.1-0.3 mol/L to leach for 15-30 min at room temperature.
7. The preparation method of the microorganism-sodium alginate-based porous composite palladium-carbon catalyst according to claim 1, which is characterized in that: the palladium source is sodium tetrachloropalladate; the palladium source is added in the form of solution with the concentration of 6-8 mmol/L.
8. The preparation method of the microorganism-sodium alginate-based porous composite palladium-carbon catalyst according to claim 1, which is characterized in that: the carbonization and reduction roasting process comprises the following steps: firstly, heating to 750-850 ℃ at the speed of 3-4 ℃/min under the protective atmosphere, preserving heat for 2.5-3.5 h, then cooling to 180-220 ℃, and preserving heat for 1.5-2.5 h under the reducing atmosphere.
9. A microorganism-sodium alginate-based porous composite palladium-carbon catalyst is characterized in that: obtained by the production method according to any one of claims 1 to 8.
CN202211202308.5A 2022-09-29 2022-09-29 Microorganism-sodium alginate-based porous composite palladium-carbon catalyst and preparation method thereof Pending CN115528262A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116284987A (en) * 2023-03-29 2023-06-23 厦门大学 Biomass-based composite gel foam and preparation method thereof
CN117912858A (en) * 2024-03-20 2024-04-19 齐鲁工业大学(山东省科学院) Porous carbon material for furfural residue-sodium alginate composite gel sphere-based supercapacitor

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116284987A (en) * 2023-03-29 2023-06-23 厦门大学 Biomass-based composite gel foam and preparation method thereof
CN117912858A (en) * 2024-03-20 2024-04-19 齐鲁工业大学(山东省科学院) Porous carbon material for furfural residue-sodium alginate composite gel sphere-based supercapacitor

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