CN106268864B - A kind of regeneration method of palladium catalyst - Google Patents

Abstract

The present invention provides a regeneration method capable of making the palladium catalyst whose activity still fails to meet production requirements after being processed by an existing regeneration method to achieve the required activity for production or a higher active palladium catalyst, comprising the following steps: Step 1: will require The impurities in the regenerated palladium catalyst are removed; Step 2: the palladium catalyst after the removal of impurities is reacted with sodium chlorate solution and hydrochloric acid; Step 3: the pH value of the solution after the reaction in Step 2 is adjusted to above 4, and dried; Step 3 4: calcining the dried sample in step 3.

Description

A kind of regeneration method of palladium catalyst

technical field

The invention relates to the technical field of chemical production, in particular to a regeneration method of a palladium catalyst.

Background technique

In the production of hydrogen peroxide, the activity of the palladium catalyst (Pd-Al ₂ O ₃ ) used for the hydrogenation of anthraquinone will gradually decrease with the prolongation of the use time. It is activated and regenerated to restore most of the activity and meet the normal production requirements. At present, there are three main types of palladium catalyst regeneration: steam regeneration, aromatic hydrocarbon regeneration and oxidation solution regeneration, or a combination of these methods. Among them, steam regeneration is the most commonly used method, that is, blowing a large amount of steam into the catalyst bed, washing the organic matter and most of the inorganic salts attached to the catalyst surface by hot steam, and re-exposing the covered active center on the catalyst surface. Thereby, the activity of the catalyst is restored. This treatment method has a better effect on the regeneration of the upper bed of the catalyst. With the deepening of the steam and the blocking and cooling of the catalyst, the steam entering the bed will gradually turn into hot water, resulting in a sharp decrease in the flow rate. The short-circuit outflow of the lower catalyst bed results in that most of the catalysts in the lower half cannot be regenerated, the overall regeneration effect is not good, the service cycle of the regenerated catalyst is short, and there are disadvantages such as large waste of working fluid and high cost.

The Chinese patent with the application number of 201510504199.6 discloses a method for regenerating an anthraquinone method hydrogen peroxide palladium catalyst, which includes the following steps: soaking in aromatic hydrocarbons at 40-60°C; saturated steam treatment at 105-115°C; aromatic hydrocarbons at 0-60°C and Soak in trioctyl phosphate solvent; 105～115℃ saturated steam treatment. Although the invention has recovered the activity of the palladium catalyst to a certain extent, the regeneration of the method is not thorough enough, and the problem that the catalyst activity is reduced due to the growth of the palladium particles cannot be solved, and the activity of the regenerated palladium catalyst cannot reach that of the new palladium catalyst. At the same time, after repeated regeneration, the activity of the regenerated palladium catalyst cannot reach the necessary activity required for production, and can only be scrapped.

Therefore, it is necessary to invent a kind of palladium catalyst that can make the palladium catalyst whose activity still fails to meet the production requirement after being processed by the existing regeneration method to achieve the required activity for the production, for the catalyst whose activity still fails to meet the production requirement after being processed by the existing regeneration method. or higher activity palladium catalyst regeneration method.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a regeneration method that can make the palladium catalyst whose activity still fails to meet the production requirement through the existing regeneration method to achieve the required activity or a higher active palladium catalyst for the production.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is:

The invention provides a regeneration method of a palladium catalyst, comprising the following steps:

Step 1: remove the impurities in the palladium catalyst that needs to be regenerated;

Step 2: the palladium catalyst after removing impurities is reacted with sodium chlorate solution and hydrochloric acid;

Step 3: adjusting the pH value of the solution reacted in step 2 to above 4, and drying;

Step 4: calcining the dried sample in step 3.

The beneficial effects of the present invention are as follows: sodium chlorate solution and hydrochloric acid are added on the palladium catalyst after removing impurities to react, and the reaction makes the metal palladium and palladium oxide particles with large crystal grains on the catalyst to be converted into palladium chloride with small crystal grains, Thereby, the problem that the activity of the palladium catalyst is difficult to recover due to the growth of the palladium particles is solved, and the strength of the alumina is well preserved; after the palladium catalyst reacts with the sodium chlorate solution and hydrochloric acid, a little alkaline solution is added to adjust the acid-base on the surface of the palladium catalyst. to obtain palladium hydroxide to fix the palladium compound produced in the treatment process with pH above 4; the sample after drying in step 3 is roasted at high temperature, so that the surface of the palladium catalyst is redistributed, and the palladium on the obtained regenerated catalyst is mainly oxidized The palladium form exists, and this palladium oxide can be pre-reduced with a reducing agent before the catalyst is used or is in-situ reduced with hydrogen in the hydrogenation reactor when the catalyst is used. After testing, it is found that the activity of the palladium catalyst regenerated by the method of the present invention is different from the new one. The activity of the palladium catalyst is comparable.

Detailed ways

In order to describe in detail the technical content, achieved objects and effects of the present invention, the following descriptions are given in conjunction with the embodiments.

The most critical concept of the present invention is: by chemically treating the large-grain metal palladium or palladium oxide contained on the cleaned and dried palladium catalyst, dispersing it into small-grain palladium chloride, thereby solving the problem in production and use. The growth of palladium particles leads to the problem that the activity of the palladium catalyst is difficult to recover, so that the activity of the regenerated palladium catalyst is higher than that of the conventional regeneration method.

The invention provides a regeneration method of a palladium catalyst, comprising the following steps:

Step 1: remove the impurities in the palladium catalyst that needs to be regenerated;

Step 2: the palladium catalyst after removing impurities is reacted with sodium chlorate solution and hydrochloric acid;

Step 3: adjusting the pH value of the solution reacted in step 2 to above 4, and drying;

Step 4: calcining the dried sample in step 3.

The reaction principle of the present invention: using the sodium chlorate-hydrochloric acid reaction method, the metal palladium or palladium oxide particles with large crystal grains are converted into palladium chloride particles with small crystal grains, so as to solve the problem that the traditional regeneration method reduces due to the growth of palladium particles. The problem that the catalyst activity is difficult to recover. The alkaline substance used to adjust the pH value of the catalyst surface during the treatment process is sodium hydroxide or potassium hydroxide or sodium carbonate or potassium carbonate or sodium bicarbonate, and the pH value of the catalyst surface is adjusted to above 4 , so as to convert the soluble compound of palladium generated during the catalyst treatment process into palladium hydroxide and fix it on the catalyst.

The relevant reactions of chemical treatment methods are as follows:

Main reaction: PdO+2HCl==PdCl ₂ +H ₂ O............(1)

Pd+Cl ₂ =PdCl ₂ .....................(2)

Pd ²⁺ +2OH ⁻ =Pd(OH) ₂ ............(3)

The reaction of formula 2 is generally carried out in a hydrochloric acid atmosphere with a concentration of about 7% to 30%. Because the hydrochloric acid in the above reaction has a strong corrosive effect on the alumina carrier, it will greatly reduce the strength of the alumina carrier. In order to alleviate this side effect, the present invention introduces active chlorine in the reaction process, so as to reduce the amount of hydrochloric acid and reduce the oxidation effect of hydrochloric acid. The corrosion effect of the aluminum carrier enhances the reaction speed and better preserves the strength of the alumina.

The action of sodium chlorate and hydrochloric acid to release active chlorine:

NaClO ₃ +HCl→HClO ₃ +NaCl................................................(4)

NaClO ₃ +3HCl→HClO ₂ +NaCl+Cl ₂ +H ₂ O......................(5)

NaClO ₂ +2HCl→HClO+Cl ₂ +H ₂ O................................(6)

The chlorine generated by formulas (5) and (6) is more active than the chloride ion separated by hydrochloric acid, and can participate in the main reaction well.

As can be seen from the above description, the beneficial effect of the present invention is: adding sodium chlorate solution and hydrochloric acid on the palladium catalyst after removing impurities to react, the reaction makes the metal palladium and palladium oxide particles with large crystal grains on the catalyst to be converted into small crystal grains palladium chloride, thereby solving the problem that the activity of the palladium catalyst is difficult to recover due to the growth of the palladium particles and the strength of the alumina can be better preserved; after the palladium catalyst reacts with sodium chlorate solution and hydrochloric acid, an alkaline solution is added to adjust The pH of the palladium catalyst surface is more than 4, and the purpose is to convert the soluble compound of the palladium that the aforementioned reaction produces into palladium hydroxide and be fixed on the catalyst, which is beneficial to the palladium replenishing operation and the washing operation of the subsequent catalyst, and the palladium hydroxide can It is firmly adsorbed on the surface of the catalyst to ensure that the palladium content of the catalyst will not be lost during subsequent treatment; the sample after drying in step 3 is roasted at high temperature to obtain a regenerated oxidized catalyst, which can be used with a reducing agent before use. Or be installed in the hydrogenation reactor with hydrogen on-site in-situ reduction, through testing, it is found that the activity of the palladium catalyst regenerated by the method of the present invention is equivalent to the activity of the new palladium catalyst.

Further, between step 3 and step 4, it also includes adding a mixed solution of palladium chloride and sodium chloride to the dried sample in step 3, soaking, filtering, and washing with water until the mixed solution does not contain chloride ions, Drying; the water is pure water whose temperature is from normal temperature to 60°C.

As can be seen from the above description, the beneficial effects of the present invention are: adding the aqueous solution of palladium chloride and sodium chloride miscible to the sample after the reaction in step 3, because the water solubility of palladium chloride is very low, adding sodium chloride for co-dissolving can form energy. Water-soluble sodium chloride palladium, the pH value of the solution is stable, which is helpful for the reasonable distribution of palladium particles on the alumina surface, and then reasonably supplements the content of palladium in the catalyst, further improves the activity of the regenerated palladium catalyst, and prolongs the regeneration of palladium. The service life of the catalyst; washing with pure water at a certain temperature completely removes the soluble impurities introduced in the regeneration process of the catalyst and ensures the performance of the catalyst.

Further, the specific operations of the step 1 are as follows: soak the palladium catalyst to be regenerated with aromatic hydrocarbons at 50-70° C. for 3-6 hours, and replace the aromatic hydrocarbons every 0.5 h; drain the palladium catalyst soaked in the aromatic hydrocarbons for use Soak the alkaline solution at 30～70℃ for 4～5h, and replace the alkaline solution every 0.5h; drain the palladium catalyst soaked in the alkaline solution and soak it in water at 30～90℃ until the palladium catalyst is soaked The aqueous solution is neutral.

As can be seen from the above description, the beneficial effects of the present invention are: by soaking the palladium catalyst to be regenerated with aromatic hydrocarbons, alkaline solution and water, the residual organic matter, the adsorbed acid substance and the alkaline substance on the palladium catalyst are washed away respectively, thereby Avoid that the regeneration effect of the palladium catalyst is affected by the impurities it adsorbs; the palladium catalyst to be regenerated is soaked in turn by using aromatic hydrocarbons, alkaline solution and water with a higher temperature, which is helpful for organic matter, acidic substances, alkalis on the palladium catalyst. Sexual substances and some other impurities are quickly washed, shortening the soaking time and improving the regeneration efficiency.

Further, the aromatic hydrocarbons are C ₉ aromatic hydrocarbons, C ₁₀ aromatic hydrocarbons, or a mixture of C ₉ aromatic hydrocarbons and C ₁₀ aromatic hydrocarbons in any proportion.

As can be seen from the above description, the beneficial effects of the present invention are: the first washing of the palladium catalyst is carried out by adopting the mixture of C ₉ aromatic hydrocarbons, C ₁₀ aromatic hydrocarbons or any ratio of C ₉ aromatic hydrocarbons and C ₁₀ aromatic hydrocarbons, which can more effectively remove the palladium catalyst sticking. Attached substances and some organic degradation products.

Further, the alkaline solution is potassium hydroxide solution, sodium hydroxide solution, ammonia water, sodium carbonate solution, sodium bicarbonate solution, potassium carbonate solution and potassium hydrogencarbonate solution, and the concentration of the alkaline solution is 0.05～0.30 mol/L.

It can be seen from the above description that the beneficial effects of the present invention are that the above-mentioned alkaline solution is relatively easy to obtain and has a low cost, and can achieve the effect of removing acidic substances on the palladium catalyst.

Further, before performing the step 1, the palladium catalyst to be regenerated is screened out, and the screening method is as follows: the waste palladium catalyst is screened with a 10-mesh screen to remove particles with a particle size below 2 mm.

As can be seen from the above description, the beneficial effect of the present invention is that the particles with a particle size of less than 2 mm are removed with a screen, so as to avoid too small particles resulting in too large resistance, which is not suitable for a fixed bed.

Further, the mol ratio of the sodium chlorate in the described sodium chlorate solution to the palladium in the palladium catalyst is 1: 1～2, and the mol ratio of the sodium chlorate in the described sodium chlorate solution to the hydrochloric acid is 1: 6 ~10.

As can be seen from the above description, the beneficial effects of the present invention are: like this, most hydrochloric acid and sodium chlorate can be guaranteed to react under the acidic atmosphere, and the amount of the medicine used is also guaranteed to be sufficient to completely convert the palladium on the catalyst into palladium chloride. Because hydrochloric acid has a strong corrosive effect on the carrier alumina of the palladium catalyst, it will greatly reduce the strength of the alumina carrier. Therefore, the action of sodium chlorate and hydrochloric acid will release active chlorine. After removing impurities, the palladium catalyst was washed and dried. Add sodium chlorate and hydrochloric acid, so that sodium chlorate reacts with most of the added hydrochloric acid to generate active chlorine, and the active chlorine and palladium generate palladium chloride, which reduces the amount of hydrochloric acid directly acting on the catalyst, and slows down the hydrochloric acid to alumina. Corrosion can better preserve the strength of alumina and speed up the reaction.

Further, the roasting temperature is 500-550° C., and the roasting time is 2-4 hours.

As can be seen from the above description, the beneficial effects of the present invention are: through the high temperature treatment, palladium chloride can be converted into palladium oxide, and the palladium can be reasonably redistributed on the alumina carrier, which is beneficial to the regenerated catalyst having good performance. Activity, selectivity and longevity.

Further, in the described step 3, the alkaline substance used for adjusting the pH value is sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate or sodium bicarbonate, and its consumption is 0.10 to 0.30% of the dry basis weight of the regenerated catalyst. .

Example 1

The regeneration method of the palladium catalyst of the present embodiment comprises the steps:

Pretreatment: sieve the waste palladium catalyst with a 10-mesh sieve, remove particles with a particle size below 2 mm, and obtain the palladium catalyst to be regenerated.

Step 1: Weigh 100g of the palladium catalyst to be regenerated (the FAH-1Q type fixed-bed palladium-alumina catalyst scrapped after 6 years) in a 500mL beaker, add 180mL of C ₁₀ aromatics at a temperature of 60°C each time for soaking, After each soaking for 30min, the aromatic hydrocarbons are separated, and then the same amount of aromatic hydrocarbons as the first time is added, and soaked in this way for 9 times, the aromatic hydrocarbons separated for the last time are light yellow;

Then, 160 mL of sodium hydroxide (NaOH) solution with a concentration of 0.1 mol/L and a temperature of 30 to 50 ° C was added to the palladium catalyst soaked in the above-mentioned aromatic hydrocarbons for soaking. After soaking and washing 10 times in the same concentration of sodium hydroxide solution as the first time, the lotion has no oil beads and is light pink;

After the catalyst washed with the alkaline solution was drained, soak and wash with 160 mL of deionized water at a temperature of 30 to 50 °C each time. After soaking for 30 minutes, add the same amount of deionized water as the first isothermal water until soaking. The aqueous solution of the catalyst is neutral.

Step 2: The catalyst washed in step 1 was placed in a drying oven at 120°C for 4 hours, and then dried in a drying oven at 200°C for 4 hours. The palladium content of the dried palladium catalyst was measured to be 0.19%, and the water absorption was 86%. Take by weighing the palladium catalyst (the molar content of palladium in the palladium catalyst is 30 × 0.0019/106.42=0.000535614 (mol)) after the above-mentioned washing and drying of 30g, and place it in a 300mL beaker;

Take a 100mL beaker, accurately weigh 0.0576g of sodium chlorate with a purity of 99% (take the molar ratio of sodium chlorate to palladium as 1:1, then the sodium chlorate consumption=0.000535614×106.44÷0.99=0.0575866(g) , where 106.44 is the molar mass of sodium chlorate, 0.99 is the purity of sodium chlorate, taking into account the precision of the balance, take 0.0576 g), dissolve it in 26 mL of deionized water with a temperature of 60 ° C, and mix this hot sodium chlorate solution with Pour it into the aforementioned 300mL beaker containing 30g of catalyst, shake the beaker to make the absorption uniform;

Accurately measure 0.31mL of concentrated hydrochloric acid with a concentration of 12mol/L (concentrated hydrochloric acid consumption=0.000535614×7÷0.012=0.312(mL) and round it to 0.31mL, wherein the concentrated hydrochloric acid consumption is 7 times the molar weight of metal palladium, and the mole of hydrochloric acid is The concentration is 12mol/L), first diluted with 1.0mL of deionized water and then added to the catalyst that has been impregnated with the sodium chlorate solution, the beaker is turned to make contact with the catalyst evenly, and after standing for 4h, the sample is placed in an oven at 120 Bake at ℃ for 3h, take out and place in a clean 300mL beaker.

Step 3: Take a 100mL beaker, accurately weigh 0.06g of sodium hydroxide with a purity of 96% (NaOH dosage=30×0.0019÷0.96=0.06(g), take the sodium hydroxide dosage as 0.19% of the catalyst weight, 0.96 NaOH purity) was dissolved in 26 mL of deionized water, then added to the 300 mL beaker containing the above-mentioned dried samples, and after turning the beaker to make the absorption uniform, then placed in an oven at 120 °C for 3 hours, and then taken out and placed in a clean 300 mL in a beaker.

Replenishing palladium: accurately weigh 0.0303g of palladium chloride with a purity of 59.5% (catalyst palladium content is 0.25% after design regeneration, 0.595 is the palladium content of palladium chloride reagent, palladium chloride supplementary amount=(0.0025-0.0019) × 30÷0.595=0.03025(g) take 0.0303g) and 0.04g of sodium chloride with a purity of 96%, dissolve in 75mL of deionized water, add this solution to the beaker of the above dried sample, soak for 1h, filter Remove dipping residue.

Washing and drying: add 100 mL of deionized water at room temperature to the solid obtained after palladium supplementation and filtration, and soak for 12 hours, separate the soaking liquid, and then wash it with 100 mL of deionized water at room temperature at a frequency of once every 1 h, and wash to the separated wash. The water was tested with 1% silver nitrate solution until no Cl ^- was detected; the catalyst samples after washing were placed in a muffle furnace and dried at 200° C. for 2 hours.

Step 4: The sample baked in step 3 is placed in a muffle furnace for calcination at 500° C. for 4 hours, which is the regeneration of the palladium catalyst.

The activity of the catalyst was evaluated using a micro-fixed-bed reactor (see "Journal of Fuzhou University (Natural Science Edition)", No. 4, 2000). The reaction temperature is 50 ° C, the pressure is normal pressure, the stirring speed is 1400 r/min, the hydrogen source adopts a hydrogen-nitrogen mixture with a hydrogen-nitrogen ratio of 3:1, the catalyst loading is 40 mL (about 20 g), and the catalyst is in the reactor before the activity test. In-situ reduction at 60-80 °C under atmospheric pressure for 20 h with a hydrogen-nitrogen mixture. The composition of the working solution used in this experiment is: the content of 2-ethylanthraquinone (EAQ) is 130g/L, the solvent is a mixture of trioctyl phosphate (TOP) and heavy aromatic hydrocarbons, the ratio is 25/75, and the amount of working solution is 240mL. The amount of H ₂ O ₂ produced in the reaction within 1.5 h was used as the hydrogen efficiency of the catalyst to compare the activity of different catalysts.

The palladium content analysis of the catalyst was carried out by the method specified in my country's petrochemical industry standard SH/T0684-1999 "Determination of Palladium Content in Molecular Sieve and Alumina-Based Catalysts (Atomic Absorption Spectrometry)".

The compressive strength of the catalyst was measured on a DL5 smart particle strength tester. 30 particles were randomly selected from each sample for testing, and the average value of the 30 particles was taken as the test result of the sample.

The test results of catalyst activity, palladium content and compressive strength are listed in Table 1.

Embodiment 2

Repeat the step of embodiment one, just change the mol ratio of sodium chlorate and palladium to 1: 1.5 in the step 2, change the mol ratio of sodium chlorate and hydrochloric acid to 1: 10, namely this example sodium chlorate consumption=0.000535614 ÷1.5×106.44÷0.99＝0.0383911(g), of which 106.44 is the molar mass of sodium chlorate, 0.99 is the purity of sodium chlorate, taking into account the precision of the balance, take 0.0384g) The amount of hydrochloric acid is 0.000535614÷1.5×10÷0.012＝ 0.29756 (mL) is rounded to 0.30mL, and the consumption of the sodium hydroxide for adjusting the pH value of the catalyst surface is still weighed 0.06g according to the ratio of Example 1, and the test method of the palladium content, activity and compressive strength of the catalyst is implemented by Example 1 is carried out, and the data are shown in Table 1.

Embodiment 3

The steps of Example 1 are repeated, except that Na ₂ CO ₃ is used when adjusting the pH value of the catalyst surface in step 3, and the ionic equation for the hydrolysis of sodium carbonate is:

CO ₃ ^2- +H ₂ O==HCO ^3- + ^OH-

HCO ₃ ^- +H ₂ O<==>H ₂ CO ₃ +OH ^-

It can be seen that the amount of alkali generated by the hydrolysis of 1 mole of sodium carbonate is similar to the amount of alkali of 2 moles of sodium hydroxide, and the amount of sodium carbonate is set as 0.10% of the catalyst weight (equivalent to 0.2% of the catalyst weight in the amount of NaOH used), for this Na ₂ The amount of CO ₃ = 30×0.001÷0.995=0.03015(g), 0.0302g was actually weighed, and 0.995 was the purity of NaOH, and the rest were carried out according to Example 1. The test data of the palladium content, activity and compressive strength of the catalyst are shown in Table 1.

Embodiment 4

The steps of Example 1 were repeated, except that the calcination conditions of the catalyst in step 4 were changed to calcination at a temperature of 550° C. for 3h.

Embodiment 5

In this example, the APC-1-Q type fixed-bed palladium-alumina catalyst that was scrapped after being used in the factory for 4 years was used as the regeneration object, and the process of Example 1 was repeated. The palladium content of the fresh catalyst of this model was measured to be 0.27 wt.%, and the palladium content of the spent catalyst was 0.21 wt.%.

Pretreatment: sieve the waste palladium catalyst with a 10-mesh sieve, remove particles with a particle size below 2 mm, and obtain the palladium catalyst to be regenerated.

Step 1: Weigh 100 g of the palladium catalyst to be regenerated in a 500 mL beaker, add 180 mL of C ₁₀ aromatic hydrocarbons at a temperature of 60 ° C for soaking each time, separate out aromatic hydrocarbons after soaking for 30 min each time, and then add the same amount as the first time. Aromatic hydrocarbons, soaked in this way for 10 times, the aromatic hydrocarbons separated in the last time are light yellow;

Then, 160 mL of sodium hydroxide (NaOH) solution with a concentration of 0.1 mol/L and a temperature of 30 to 50 ° C was added to the palladium catalyst soaked in the above-mentioned aromatic hydrocarbons for soaking. After soaking and washing 10 times in the same concentration of sodium hydroxide solution as the first time, the lotion has no oil beads and is light pink;

After the catalyst washed with the alkaline solution was drained, soak and wash with 160 mL of deionized water at a temperature of 30 to 50 °C each time. After soaking for 30 minutes, add the same amount of deionized water as the first isothermal water until soaking. The aqueous solution of the catalyst is neutral.

Step 2: The catalyst washed in step 1 was placed in a drying oven at 120°C for 4 hours, and then dried in a drying oven at 200°C for 4 hours. The palladium content of the dried palladium catalyst was measured to be 0.21%, and the water absorption was 82%. Take by weighing the palladium catalyst (the molar content of palladium in the palladium catalyst is 30 × 0.0021/106.42=0.000591994 (mol)) after the above-mentioned washing and drying of 30g, and place it in a 300mL beaker;

Take a 100mL beaker and accurately weigh 0.0636g of sodium chlorate with a purity of 99% (sodium chlorate dosage=0.000591994×106.44÷0.99=0.0636483(g), where 106.44 is the molar mass of sodium chlorate and 0.99 is chloric acid The purity of sodium, taking into account the precision of the balance, take 0.0636g), dissolve it in 25mL of deionized water with a temperature of 60 ° C, and pour this hot sodium chlorate solution into the aforementioned 300mL beaker containing 30g of catalyst, shake the beaker, make the absorption uniform;

Accurately measure 0.35mL of concentrated hydrochloric acid with a concentration of 12mol/L (concentrated hydrochloric acid consumption=0.000591994×7÷0.012=0.345(mL) and round it to 0.35mL, wherein the concentrated hydrochloric acid consumption is 7 times the molar weight of metal palladium, and the mole of hydrochloric acid is The concentration is 12mol/L), first diluted with 1.0mL of deionized water and then added to the catalyst that has been impregnated with the sodium chlorate solution, the beaker is turned to make contact with the catalyst evenly, and after standing for 4h, the sample is placed in an oven at 120 Bake at ℃ for 3h, take out and place in a clean 300mL beaker.

Step 3: Take a 100mL beaker, accurately weigh 0.0625g of sodium hydroxide with a purity of 96% (NaOH dosage=30×0.002÷0.96=0.0625(g), take the sodium hydroxide dosage as 0.20% of the catalyst weight, 0.96 NaOH purity) was dissolved in 25 mL of deionized water, and then added to the 300 mL beaker containing the above-mentioned dried samples. After turning the beaker to make the absorption uniform, it was placed in an oven at 120 °C for 3 hours, and then taken out and placed in a clean 300 mL in a beaker.

Replenishing palladium: accurately weigh 0.0454g of palladium chloride with a purity of 59.5% (the catalyst palladium content is 0.30% after the design regeneration, 0.595 is the palladium content of the palladium chloride reagent, the palladium chloride supplementary amount=(0.003-0.0021) × 30÷0.595=0.04538(g) take 0.0454g) and 0.05g sodium chloride with a purity of 96%, dissolve in 75mL deionized water, add this solution to the beaker of the above dried sample, soak for 1h, filter Remove dipping residue.

Washing and drying: add 100 mL of deionized water at room temperature to the solid obtained after palladium supplementation and filtration, and soak for 12 hours, separate the soaking liquid, and then wash it with 100 mL of deionized water at room temperature at a frequency of once every 1 h, and wash to the separated wash. The water was tested with 1% silver nitrate solution until no Cl ^- was detected; the catalyst samples after washing were placed in a muffle furnace and dried at 200° C. for 2 hours.

Step 4: The sample baked in step 3 is placed in a muffle furnace for calcination at 500° C. for 4 hours, which is the regeneration of the palladium catalyst.

The activity, palladium content and compressive strength of the catalyst were tested according to the method in Example 1, and the data are listed in Table 1.

Comparative Example 1

Use a 10-mesh sieve to screen the waste FAH-1Q palladium catalyst after 6 years of use in the factory to remove particles with a particle size of less than 2 mm, then weigh 100 g of the catalyst sample into a 500 mL beaker, and add 180 mL each time at a temperature of Soak the C ₁₀ aromatics at 60°C, separate out the aromatics after each soaking for 30min, then add the same amount of aromatics as the first time, soak 9 times in this way, the aromatics separated in the last time are light yellow, and then put in the oven After drying at 200°C for 4 hours, it was lowered to room temperature to obtain the palladium catalyst required for the experiment. The test methods for the activity, palladium content and compressive strength of the catalyst are carried out according to Example 1, and the data are listed in Table 1.

Comparative Example 2

The process of Comparative Example 1 was repeated, except that the sample was changed to APC-1-Q, which was used in the factory for 4 years, and the test methods of catalyst activity, palladium content and compressive strength were carried out according to Example 1, and the data were listed in Table 1.

Comparative Example 3

Get fresh FAH-1Q catalyst, its activity, palladium content and the test method of compressive strength are carried out according to embodiment 1, data are listed in table 1.

Comparative Example 4

Get fresh APC-1-Q catalyst, its activity, palladium content and the test method of compressive strength are carried out according to embodiment 1, data are listed in table 1.

The catalyst activity evaluation results are shown in Table 1.

Table 1. Activity comparison of several catalysts

It can be seen from Table 1 that after the spent catalyst is treated by the regeneration method of the present invention, the activity and palladium content basically reach the level of the new catalyst, and the mechanical strength is comparable to that of the untreated pre-regenerated catalyst.

To sum up, in the regeneration method of palladium catalyst provided by the present invention, sodium chlorate solution and hydrochloric acid are added to the palladium catalyst after removing impurities to react, and this reaction makes the metal palladium particles and palladium oxide particles with large crystal grains on the catalyst to be converted. It is palladium chloride with small crystal grains, so as to solve the problem that the activity of palladium catalyst is difficult to recover due to the growth of palladium particles and better preserve the strength of alumina; after the palladium catalyst reacts with sodium chlorate solution and hydrochloric acid, add a little The alkaline solution adjusts the pH of the surface of the palladium catalyst to a pH of 4 or more to obtain palladium hydroxide to fix the palladium compound produced in the treatment process; the dried sample in step 3 is roasted at high temperature to obtain a regenerated catalyst palladium oxide, which is found through testing. The activity of the palladium catalyst regenerated by the method of the present invention is equivalent to the activity of the new palladium catalyst; by soaking the catalyst to be regenerated with aromatic hydrocarbons, alkaline solution and water, the residual organic matter and adsorbed acidic substances on the palladium catalyst are washed away respectively. and alkaline substances, thereby avoiding the influence of the impurity adsorbed on the activity of the regenerated palladium catalyst; after the reaction in step 3, the sample is added with palladium chloride and sodium chloride solution to supplement the content of palladium in the palladium catalyst, and further improve the regenerated palladium catalyst The activity of the regenerated palladium catalyst is extended to prolong the service life of the regenerated palladium catalyst; the catalyst after the palladium replenishment is washed to remove the impurities introduced in the regeneration process, so as to avoid the influence of impurities on the catalyst activity and selectivity; the sample after the palladium replenishment and washing is dried and high temperature roasting, obtain the oxidation state regeneration catalyst that palladium is redistributed again, find through testing, adopt the activity of the palladium catalyst of the inventive method regeneration and the activity of new palladium catalyst to be quite, and compressive strength and the compressive strength of regeneration front catalyst are quite .

The above are only the embodiments of the present invention, and are not intended to limit the scope of the patent of the present invention. All equivalent transformations made by using the contents of the description of the present invention, or directly or indirectly applied in the relevant technical fields, are similarly included in the scope of the present invention. within the scope of patent protection.

Claims (7)

1. a kind of regeneration method of palladium catalyst, which comprises the following steps:

Step 1: the impurity needed in regenerated palladium catalyst is removed；

Step 2: by remove impurity after palladium catalyst dry, first with equi-volume impregnating impregnate sodium chlorate solution, then and The hydrochloric acid of 12mol/L reacts, and the hydrochloric acid is reacted with sodium chlorate solution generates Active Chlorine, dries after standing；The sodium chlorate is molten The molar ratio of the palladium in sodium chlorate and palladium catalyst in liquid is 1: 1~2, the sodium chlorate and hydrochloric acid in the sodium chlorate solution Molar ratio is 1: 6~10；

Step 3: the pH value of the solution after step 2 reaction being adjusted to 4 or more, drying；

Step 4: the sample after step 3 drying is roasted.

2. the regeneration method of palladium catalyst according to claim 1, which is characterized in that between step 3 and step 4, also Including the mixed liquor of palladium chloride and sodium chloride is added into the sample after step 3 drying, impregnates, filtering, add water washing until mixed Close liquid not chloride ion-containing, drying.

3. the regeneration method of palladium catalyst according to claim 1, which is characterized in that the concrete operations of the step 1 are as follows: 50~70 DEG C of aromatic hydrocarbons of regenerated palladium catalyst will be needed to impregnate 3~6h, replace the primary aromatic hydrocarbons every 0.5h；By aromatic hydrocarbons The palladium catalyst impregnated, which is drained, impregnates 4~5h with 30~70 DEG C of alkaline solution, and it is molten to replace the primary alkalinity every 0.5h Liquid；The palladium catalyst that alkaline solution was impregnated drains the water immersion with 30~90 DEG C, until being soaked with the aqueous solution of palladium catalyst For neutrality.

4. the regeneration method of palladium catalyst according to claim 3, which is characterized in that the aromatic hydrocarbons is C₉Aromatic hydrocarbons, C₁₀Virtue Hydrocarbon or C₉Aromatic hydrocarbons and C₁₀The mixture of aromatic hydrocarbons arbitrary proportion.

5. the regeneration method of palladium catalyst according to claim 3, which is characterized in that the alkaline solution is potassium hydroxide Solution, sodium hydroxide solution, ammonium hydroxide, sodium carbonate liquor, sodium bicarbonate solution, solution of potassium carbonate and potassium bicarbonate solution, it is described The concentration of alkaline solution is 0.05~0.30mol/L.

6. the regeneration method of palladium catalyst according to claim 1, which is characterized in that sieved before the step 1 Regenerated palladium catalyst, the method for screening are needed out are as follows: are sieved with the sieve of 10 mesh to waste and old palladium catalyst, removed partial size In 2mm particle below.

7. the regeneration method of palladium catalyst according to claim 1, which is characterized in that the temperature of the roasting be 500~ 550 DEG C, the time of the roasting is 2~4h.