Summary of the invention
The object of the present invention is to provide a kind of preparation method of platinum carbon catalyst, solve the platinum existed in prior art and adhere to insecure and that the low catalytic activity caused of decentralization is low and service life is short technical problem at carrier carbon surface.
The technical solution used in the present invention is: a kind of preparation method of platinum carbon catalyst, implements according to following concrete steps:
Step 1: the modification of absorbent charcoal carrier:
1.1, be 200-300 order by granularity, specific area is 800-1200m
2/ g, the active carbon concentration that average pore radius is greater than 1.5nm is the salpeter solution reflow treatment 1h-3h of 1%-10%, and then spending the active carbon after deionized water reflow treatment to the pH of cleaning solution is 6-7, dry, obtains pretreated absorbent charcoal carrier;
1.2, pretreated absorbent charcoal carrier being immersed in concentration is in the aqueous surfactant solution of 0.1-1.0%, stirs 1-3h and makes it mix and reach adsorption equilibrium, obtain modified active carbon suspension;
Step 2: the preparation of platinum precursor solution:
Take containing platinum compounds, adding deionized water, to be diluted to platinum concentration be 5-15g/L, under agitation, with salt acid for adjusting pH to 1-5, and obtained platinum precursor solution;
Step 3: the load of platinum presoma:
Platinum precursor solution obtained in step 2 is joined in modified active high-area carbon suspension obtained in step 1 with the speed of 500-1500ml/min, obtains mixed liquor A;
Step 4: adding inorganic base to the pH of solution in mixed liquor A is 9-12, adds the dispersant of liquid gross mass 0.1-1.0% simultaneously, stirs 1-5h, obtains the little and dispersion liquid B of the deposit seed be evenly distributed of particle;
Step 5: add reducing agent in dispersion liquid B, be 1:2-1:10 containing platinum element in platinum compounds and reducing agent mass ratio, under agitation, cooling after 60-90 DEG C of reduction 3-5h, centrifugal filtration obtain particle, spend in deionized water to cleaning solution and exist without chlorion, centrifuge dries, and obtains platinum carbon catalyst.
Feature of the present invention is also,
Surfactant is one or several of stearic acid, neopelex, fatty glyceride and polysorbate.
Be one or several in platinum nitrate, citric acid platinum, chloroplatinic acid, platinic sulfate and platinum amine complex containing platinum compounds.
Inorganic base is NaOH, KOH, Na
2cO
3with one or several in ammoniacal liquor.
Dispersant is one or both in sodium pyrophosphate, calgon, triethyl group hexyl phosphoric acid, lauryl sodium sulfate, methyl anyl alcohol, cellulose derivative, polyacrylamide.
Reducing agent is one or several in formic acid, sodium formate, formaldehyde, hydrazine hydrate, glycerine, glucose.
The invention has the beneficial effects as follows, pretreated absorbent charcoal carrier is immersed in the aqueous solution of surfactant by adopting by the present invention, then platinum precursor solution is added drop-wise in the above-mentioned modified absorbent charcoal carrier aqueous solution, improve the active force between platinum and absorbent charcoal carrier, platinum adhesive force on the activated carbon increases, make catalyst metal difficult drop-off in the process recycled, improve catalytic activity and the service life of catalyst; In addition, in the process that crystal is grown up, add dispersant, prevent sedimentary reunion, improve the dispersiveness of platinum in carried by active carbon surface, and obtained platinum carbon catalyst particle is little, make the platinum carbon catalyst performance that obtains homogeneous, stable.Therefore, in preparation method of the present invention, the common use of surfactant and dispersant makes that the platinum carbon catalyst catalytic activity of preparation is high, long service life.
Detailed description of the invention
Below in conjunction with specific embodiments and the drawings, the present invention is described in detail.
The preparation method of a kind of platinum carbon catalyst of the present invention, comprises the following steps:
Step 1: the modification of absorbent charcoal carrier:
1.1, be 200-300 order by granularity, specific area is 800-1200m
2/ g, the active carbon concentration that average pore radius is greater than 1.5nm is the salpeter solution reflow treatment 1h-3h of 1%-10%, and then spending the active carbon after deionized water reflow treatment to the pH of cleaning solution is 6-7, dry, obtains pretreated absorbent charcoal carrier;
1.2, pretreated absorbent charcoal carrier being immersed in concentration is in the aqueous surfactant solution of 0.1-1.0%, stirs 1-3h and makes it mix and reach adsorption equilibrium, obtain modified active carbon suspension;
Step 2: the preparation of platinum precursor solution:
Take containing platinum compounds, adding deionized water, to be diluted to platinum concentration be 5-15g/L, under agitation, with salt acid for adjusting pH to 1 ~ 5, and obtained platinum precursor solution;
Step 3: the load of platinum presoma:
Platinum precursor solution obtained in step 2 is joined in modified activated carbon suspension obtained in step 1 with the speed of 500-1500ml/min, obtains mixed liquor A;
Step 4: adding inorganic base to the pH of solution in mixed liquor A is 9-12, adds the dispersant of total amount of liquid 0.1-1.0% simultaneously, stirs 1-5h, obtains the little and dispersion liquid B of the deposit seed be evenly distributed of particle;
Step 5: add reducing agent in dispersion liquid B is 1:2-1:10 containing platinum element in platinum compounds and reducing agent mass ratio, under agitation, cooling after 60-90 DEG C of reduction 3-5h, centrifugal filtration obtain particle, spend in deionized water to cleaning solution and exist without chlorion, centrifuge dries, and obtains product.
Wherein, surfactant is one or several of stearic acid, neopelex, fatty glyceride and polysorbate; Be one or several in platinum nitrate, citric acid platinum, chloroplatinic acid, platinic sulfate and platinum amine complex containing platinum compounds; Inorganic base is NaOH, KOH, Na
2cO
3with one or several in ammoniacal liquor; Dispersant is one or both in sodium pyrophosphate, calgon, triethyl group hexyl phosphoric acid, lauryl sodium sulfate, methyl anyl alcohol, cellulose derivative, polyacrylamide; Reducing agent is one or several in formic acid, sodium formate, formaldehyde, hydrazine hydrate, glycerine, glucose.
As can be seen from Figure 1, the platinum carbon catalyst particle agglomeration phenomenon prepared of the present invention is less.
By active carbon first pretreatment in the aqueous solution containing surfactant in the present invention, add the solution containing platinum compounds again, the platinum adhesive force on the activated carbon after reduction can be significantly improved, platinum adhesive force on the activated carbon increases, make catalyst metal difficult drop-off in the process recycled, improve catalytic activity and the service life of catalyst; In addition, in the process that crystal is grown up, add dispersant, prevent sedimentary reunion, improve the dispersiveness of platinum particles in carried by active carbon surface, and obtained platinum carbon catalyst particle is little, make the platinum carbon catalyst performance that obtains homogeneous, stable.Therefore, in preparation method of the present invention, the common use of surfactant and dispersant makes that the platinum carbon catalyst catalytic activity of preparation is high, long service life.
Embodiment 1
Be 200 orders by granularity, specific area 800m
2the mass concentration that the active carbon of/g, average pore radius 2nm is placed in boiling is the salpeter solution reflow treatment 1h of 1%, and then spending the active carbon after deionized water reflow treatment to the pH of cleaning solution is 7, dry, obtains pretreated absorbent charcoal carrier; Pretreated absorbent charcoal carrier being immersed in mass concentration is in the stearic acid aqueous solution of 0.1%, stirs 3h and makes it mix and reach adsorption equilibrium, obtain modified active carbon suspension;
Take platinum nitrate, adding deionized water, to be diluted to platinum concentration be 5g/L, under agitation, with salt acid for adjusting pH to 3, and obtained platinum precursor solution; Platinum precursor solution joins in modified activated carbon suspension with the speed of 500ml/min, obtains mixed liquor A;
In mixed liquor A, add NaOH to the pH of solution is 12, adds the calgon of mixed liquor A total amount 0.1% simultaneously, stirs 1h, obtains the little and dispersion liquid B of the deposit seed be evenly distributed of particle; In dispersion liquid B, add formic acid, the mass ratio of platinum element and formic acid is 1:2, and cooling after stirring reduction 3h at 90 DEG C, filtration obtain particle, and spend in deionized water particle to cleaning solution and exist without chlorion, namely centrifuge dripping obtains platinum carbon catalyst.
Embodiment 2
Be 300 orders by granularity, specific area 1200m
2the mass concentration that the active carbon of/g, average pore radius 2.5nm is placed in boiling is the salpeter solution reflow treatment 2h of 4%, and then spending the active carbon after deionized water reflow treatment to the pH of cleaning solution is 6, dry, obtains pretreated absorbent charcoal carrier; Pretreated absorbent charcoal carrier being immersed in concentration is in the sodium dodecyl benzene sulfonate aqueous solution of 0.3%, stirs 1h and makes it mix and reach adsorption equilibrium, obtain modified active carbon suspension;
Take citric acid platinum, adding deionized water, to be diluted to platinum concentration be 10g/L, under agitation, with salt acid for adjusting pH to 1, and obtained platinum precursor solution; Platinum precursor solution joins in modified activated carbon suspension with the speed of 1000ml/min, obtains mixed liquor A;
In mixed liquor A, add KOH to the pH of solution is 9, adds the methyl anyl alcohol of mixed liquor A total amount 0.3% simultaneously, stirs 2h, obtains the little and dispersion liquid B of the deposit seed be evenly distributed of particle; In dispersion liquid B, add hydrazine hydrate, the mass ratio of platinum element and hydrazine hydrate is 1:10, and cooling after stirring reduction 5h at 60 DEG C, filtration obtain particle, and spend in deionized water particle to cleaning solution and exist without chlorion, namely centrifuge dripping obtains platinum carbon catalyst.
Embodiment 3
Be 250 orders by granularity, specific area 1000m
2the mass concentration that the active carbon of/g, average pore radius 3nm is placed in boiling is the salpeter solution reflow treatment 3h of 10%, and then spending the active carbon after deionized water reflow treatment to the pH of cleaning solution is 6, obtains pretreated absorbent charcoal carrier after drying; Pretreated absorbent charcoal carrier being immersed in mass fraction is in the fatty acid glycerine aqueous solution of ester of 0.7%, stirs 2h and makes it mix and reach adsorption equilibrium, obtain modified active carbon suspension;
Take platinic sulfate, adding deionized water, to be diluted to platinum concentration be 15g/L, under agitation, with salt acid for adjusting pH to 5, and obtained platinum precursor solution; Platinum precursor solution joins in modified activated carbon suspension with the speed of 1500ml/min, obtains mixed liquor A;
Na is added in mixed liquor A
2cO
3pH to solution is 11, adds the sodium pyrophosphate of mixed liquor A total amount 1% simultaneously, stirs 3h, obtains the little and dispersion liquid B of the deposit seed be evenly distributed of particle; In dispersion liquid B, add glycerine, the mass ratio of platinum element and glycerine is 1:4, and cooling after stirring reduction 4h at 80 DEG C, filtration obtain particle, and spend in deionized water particle to cleaning solution and exist without chlorion, namely centrifuge dripping obtains platinum carbon catalyst.
Embodiment 4
Be 200 orders by granularity, specific area 1100m
2the mass concentration that the active carbon of/g, average pore radius 2nm is placed in boiling is the salpeter solution reflow treatment 2h of 6%, and then spending the active carbon after deionized water reflow treatment to the pH of cleaning solution is 7, dry, obtains pretreated absorbent charcoal carrier; Pretreated absorbent charcoal carrier being immersed in concentration is in the polysorbate aqueous solution of 1%, stirs 2.5h and makes it mix and reach adsorption equilibrium, obtain modified active carbon suspension;
Take chloroplatinic acid, adding deionized water, to be diluted to platinum concentration be 8g/L, under agitation, with salt acid for adjusting pH to 2, and obtained platinum precursor solution; Platinum precursor solution joins in modified activated carbon suspension with the speed of 1200ml/min, obtains mixed liquor A;
In mixed liquor A, adding ammoniacal liquor to the pH of solution is 10, adds the cellulose derivative of mixed liquor A total amount 0.6% simultaneously, stirs 5h, obtains the little and dispersion liquid B of the deposit seed be evenly distributed of particle; In dispersion liquid B, add sodium formate, the mass ratio of platinum element and sodium formate is 1:8, and cooling after stirring reduction 4h at 70 DEG C, filtration obtain particle, and spend in deionized water particle to cleaning solution and exist without chlorion, namely centrifuge dripping obtains platinum carbon catalyst.
Comparative example 1
As different from Example 1, in comparative example 1, the preparation process of platinum carbon catalyst does not add surfactant, and other condition is constant.
Comparative example 2
As different from Example 1, in comparative example 2, the preparation process of platinum carbon catalyst does not add dispersant, and other condition is constant.
Comparative example 3
As different from Example 1, in comparative example 2, the preparation process of platinum carbon catalyst does not add surfactant and dispersant, and other condition is constant.
When in platinum carbon catalyst prepared by the embodiment of the present invention 1 ~ 4 and comparative example, the platinum carbon catalyst prepared carries out hydrogenation to o-nitrochlorobenzene, catalytic performance is as shown in table 1:
Table 1
As can be seen from Table 1, when the hydrogenation process of catalysis to o-nitrochlorobenzene, within the identical reaction time, the platinum carbon catalyst adopting the present invention to prepare can significantly improve the yield of hydrogenation o-nitrochlorobenzene and apply mechanically number of times, in addition, as can also be seen from Table 1, only add surfactant in catalyst preparation process or only add dispersant, obtained catalyst is when the hydrogenation process of catalysis to o-nitrochlorobenzene, the yield of hydrogenation o-nitrochlorobenzene and apply mechanically number of times relative to the catalyst neither adding surfactant and also do not add dispersant in catalyst preparation process and prepare and improve, but when both added-time in preparation process, namely the platinum carbon catalyst prepared of the inventive method is when the hydrogenation process of catalysis to o-nitrochlorobenzene, within the identical reaction time, the yield of hydrogenation o-nitrochlorobenzene and apply mechanically number of times and significantly improve, the common use demonstrating surfactant and dispersant has cooperative effect, make the platinum charcoal Pd/carbon catalyst catalytic activity of preparation high, long service life.In sum, catalytic activity high-area carbon is through certain density aqueous surfactant solution process, and add dispersant in the process of growing up at platiniferous crystal, the platinum carbon catalyst of preparation not only can effectively improve platinum carbon catalyst activity, apply mechanically number of times, and the platinum carbon catalyst particle diameter obtained is little and evenly.