Method for preparing methane dry reforming catalyst by recycling waste reforming catalyst, catalyst and methane dry reforming method

Abstract

The invention discloses a method for preparing a methane dry reforming catalyst by recycling a waste reforming catalyst, the catalyst and a methane dry reforming method. The method comprises the following steps: (1) roasting the waste Pt-Re / Al2O3 reforming catalyst, and leaching the roasted waste Pt-Re / Al2O3 reforming catalyst in a solution composed of acid, hydrogen peroxide and water to obtain a waste reforming catalyst leachate containing Pt, Re and Al ions; (2) co-extracting platinum and rhenium in the leachate by using an N235 + TBP compound extracting agent to obtain an organic phase containing platinum and rhenium; (3) carrying out back extraction on the platinum-rhenium-containing organic phase by using NH3.H2O to obtain a platinum-rhenium mixed solution; (4) adding the gamma-Al2O3 carrier into the platinum-rhenium mixed solution, carrying out dipping treatment, and sequentially carrying out drying, grinding and roasting treatment; and (5) calcining in an H2 atmosphere to obtain the methane dry reforming catalyst. Platinum and rhenium are separated and recycled from the waste reforming catalyst through extraction, the methane dry reforming catalyst is prepared through an impregnation method, and the method has the advantages of being environmentally friendly, free of pollution, low in cost, high in utilization rate and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal catalytic carbon fixation catalysts, and specifically relates to a method for recycling and reusing waste reforming catalysts (recycling and reusing precious metals platinum and rhenium) to prepare a methane dry reforming catalyst (Pt-Re / Al 2 O 3 Catalyst) method, catalyst and methane dry reforming method. Background Art

[0002] Against the backdrop of economic growth and industrial expansion, the demand for high-octane gasoline produced by the catalytic reforming process of naphtha has increased rapidly, which has also promoted the application and development of reforming catalysts. Petrochemical catalysts are consumables, and a huge amount of them are scrapped in my country every year. In addition, the precious metal platinum (Pt) is expensive and scarce in resources. At the same time, it also has good high-temperature oxidation resistance and chemical stability, is easy to process and form, and has a wide range of applications. Rhenium (Re) is rare in nature and exists in dispersion, so it is expensive and has a high cost. Platinum-rhenium reforming catalyst is currently the most widely used reforming catalyst. Platinum in the catalyst mainly plays a catalytic role, and the main role of rhenium is to reduce or prevent the "agglomeration" of metal components, improve the carbon capacity and stability of the catalyst, and use it in fixed bed reactors. The service life of the catalyst is extended by catalyst regeneration, the generation of waste is reduced, the efficiency and stability of the catalyst are improved, the activity and selectivity of the catalyst are restored, and it can be reused, reducing the demand for new catalysts, thereby reducing production costs and resource consumption.

[0003] Hydrogen, a byproduct of methane dry reforming, is also the cheapest source of hydrogen for refinery hydrogenation units. Platinum and rhenium in spent reforming catalysts have great potential for recycling as secondary resources. 4 ) and carbon dioxide (CO 2 ) is the process of converting these two greenhouse gases into synthesis gas and reacting with the catalyst. The carbon fixation catalyst used in methane dry reforming can promote the recycling of clean energy and reduce environmental pollution. At present, the domestic method for recovering precious metal platinum and rhenium is generally wet recovery, and the method for catalyst synthesis is impregnation. The catalytic reforming technology has also become stable and mature, but there is currently no process for recovering platinum and rhenium from waste reforming catalysts and regenerating them to synthesize catalysts with thermal catalytic properties for methane dry reforming. Summary of the invention

[0004] Based on this, the purpose of the present invention is to provide a method for recovering and reusing precious metals in waste reforming catalysts to prepare methane dry reforming catalysts, catalysts and methane dry reforming methods. The present invention uses N235+TBP extractant to co-extract precious metals platinum and rhenium from waste reforming catalyst leachate through a simple extraction process, and uses an impregnation method to prepare a low-cost, high-activity and good-stability Pt-Re / Al for thermal catalytic carbon fixation. 2 O 3 The catalyst has excellent thermal catalytic performance for methane dry reforming.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for recycling a waste reforming catalyst to prepare a methane dry reforming catalyst, comprising the following steps:

[0007] (1) Waste Pt-Re / Al 2 O 3 The reforming catalyst is roasted, and after the roasting is completed, it is placed in a solution consisting of acid, hydrogen peroxide and water for leaching to obtain a spent reforming catalyst leachate containing Pt ions, Re ions and Al ions;

[0008] (2) co-extracting platinum and rhenium in the waste reforming catalyst leachate with a N235+TBP composite extractant to obtain an organic phase containing platinum and rhenium;

[0009] (3) Using NH 3 ·H 2 O stripping the organic phase containing platinum-rhenium to obtain a platinum-rhenium mixed solution;

[0010] (4) γ-Al 2 O 3 The carrier is added into the platinum-rhenium mixed solution and stirred for impregnation treatment, and after impregnation, it is dried, ground and calcined in sequence;

[0011] (5) the product obtained by the calcination treatment is heated to 100 °C. 2 The methane dry reforming catalyst Pt-Re / Al is obtained by calcining under a molten-hydrogen atmosphere. 2 O 3 .

[0012] In the above-mentioned method for recycling and reusing the waste reforming catalyst to prepare a methane dry reforming catalyst, in step (1), in the calcination step, the temperature is 400° C. and the time is 4 hours;

[0013] In the solution consisting of acid, hydrogen peroxide and water, the concentration of acid is 2.0 M, H 2 O 2The mass concentration is 5%; wherein the acid comprises hydrochloric acid;

[0014] In the leaching step, the liquid-to-solid ratio is 5 g:1 mL, the leaching temperature is 120° C., and the leaching time is 3 h;

[0015] As an example, in the spent reforming catalyst leachate, the concentration of Pt ions is 100 ppm, the concentration of Re ions is 200 ppm, and the concentration of Al ions is 900 ppm.

[0016] In the above-mentioned method for recycling and reusing the waste reforming catalyst to prepare the methane dry reforming catalyst, the N235+TBP composite extractant is composed of N235, TBP and a diluent, and the diluent is preferably petroleum ether;

[0017] In terms of mass percentage, in the N235+TBP compound extractant, the concentration of the N235 extractant is 10% to 30%, the concentration of TBP is 5% to 20%, and the concentration of the diluent is 50% to 85%; as an example, the compound extractant is selected from any one of 10% N235+5% TBP, 10% N235+10% TBP, 20% N235+5% TBP, 20% N235+10% TBP, 30% N235+5% TBP, and 30% N235+10% TBP; in the present invention, the term N235 refers to the abbreviation of trioctyl tertiary amine, and the term TBP refers to the abbreviation of tributyl phosphate. In the co-extraction step, the co-extraction ratio A / O=1:(1 to 1.5), such as 1:1 or 1:1.5; the co-extraction time is 5 to 20 minutes, specifically 5 minutes, 10 minutes, 15 minutes or 20 minutes;

[0018] The method further comprises: adjusting the pH of the co-extraction system to 1-7 before the co-extraction, specifically, pH=1, 2, 3, 4, 5, 6 or 7.

[0019] In the above-mentioned method for recycling and reusing the waste reforming catalyst to prepare the methane dry reforming catalyst, the NH 3 ·H 2 The concentration of O is 10% to 20%, specifically 10%, 15% or 20%;

[0020] In the stripping step, the stripping ratio A / O=1:(1-1.5), specifically 1:1, 1:1.5; the stripping time is 5-20 min, specifically 5 min, 10 min, 15 min or 20 min;

[0021] After the back extraction, the method further comprises: adjusting the pH of the back extracted system to the pH value of the co-extraction step, and then separating the aqueous phase and the organic phase. Specifically, the pH is 1, 2, 3, 4, 5, 6 or 7.

[0022] In the above-mentioned method for recycling and reusing the waste reforming catalyst to prepare a methane dry reforming catalyst, the mass fraction ratio of platinum to rhenium in the platinum-rhenium mixed solution is 1:(0.5-2), specifically 1:1, 1:2 or 2:1;

[0023] The γ-Al in the methane dry reforming catalyst 2 O 3 The mass fraction of the carrier is 80% to 99.97%, preferably 99.94% to 99.97%, such as 99.94%, 99.96wt%, 99.97%.

[0024] In the above-mentioned method for recycling and reusing the waste reforming catalyst to prepare the methane dry reforming catalyst, in the impregnation treatment step, the solid-liquid ratio is 1:20, the temperature is 80°C, and the stirring time is 9h to 12h; it can be understood that the solid-liquid ratio of 1:20 means that per 1g of γ-Al 2 O 3 The carrier corresponds to 20 mL of the platinum-rhenium mixed solution; as an example, the stirring time is specifically 9 h, 10 h or 12 h;

[0025] In the drying step, the drying is vacuum drying, the drying temperature is 50°C to 80°C, such as 50°C, 60°C, 80°C; the drying time is 12h; further, the method further comprises a grinding step for 30min after the drying.

[0026] In the calcination step, the calcination time is 3 to 5 hours, specifically 3 hours, 4 hours, and 5 hours; the calcination temperature is 400° C. to 600° C., specifically 400° C., 500° C., and 600° C. As an example, the heating rate is 5° C. / min. The calcination process is specifically carried out in a muffle furnace.

[0027] In the above-mentioned method for recycling and reusing the spent reforming catalyst to prepare a methane dry reforming catalyst, in the calcination step, H 2 The flow rate is 30 sccm;

[0028] In the calcination step, the calcination temperature is 400°C to 600°C, specifically 400°C, 500°C, and 600°C; the calcination time is 3 to 5 hours, specifically 3 hours, 4 hours, and 5 hours. As an example, the heating rate is 5°C / min. The calcination treatment is specifically carried out in a tubular furnace. Furthermore, the method further includes a step of grinding for 30 minutes after the calcination.

[0029] In a second aspect, the present invention further provides a methane dry reforming catalyst Pt-Re / Al prepared by any of the methods described above. 2 O 3 .

[0030] In a third aspect, the present invention provides a methane dry reforming method, comprising the following steps: using the methane dry reforming catalyst Pt-Re / Al 2 O 3 A mixed gas containing methane and carbon dioxide is reacted with the catalyst in a fixed bed reactor.

[0031] In the above-mentioned methane dry reforming method, the volume ratio of methane to carbon dioxide in the mixed gas is 1:(1-2), such as 1:1 or 1:2;

[0032] The flow rates of methane and carbon dioxide corresponding to each 0.2g of the catalyst are (2-4) ml / min, such as 2 ml / min or 4 ml / min;

[0033] The reaction temperature is 400-850°C, specifically 400°C, 500°C, 600°C, 700°C, 800°C or 850°C;

[0034] The mixed gas uses nitrogen or argon as the balance gas, and the volume fractions of methane and carbon dioxide in the mixed gas are both 10-20%, such as 10% or 20%.

[0035] The present invention has the following beneficial effects:

[0036] (1) A simple process for recovering and reusing precious metals from waste reforming catalysts to prepare carbon fixation catalysts has been developed. The precious metal platinum and rhenium are recovered by the simplest extraction separation, and then recycled by the impregnation method to prepare low-cost and high-activity thermal catalysts. The overall scheme is green and pollution-free, with low raw material cost, high utilization rate, low energy consumption, good effect, and is suitable for large-scale preparation.

[0037] (2) Precious metals platinum rhenium and γ-Al 2 O 3 The combination of the support and the thermal catalytic CH 4 / CO 2 In dry reforming, CH 4 , CO 2 The conversion rate of CO and H 2 The yield is as high as 98.99%, and it has strong carbon fixation and cleaning capabilities.

[0038] (3) Pt-Re / Al prepared by the present invention 2 O 3 Catalysts are of guiding significance for recycling waste materials to maximize resource utilization and provide new insights into alleviating the environmental pollution challenges caused by current fossil fuel consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1This is a process flow chart for recovering and reusing waste reforming catalyst to prepare methane dry reforming catalyst (carbon fixing catalyst) in an embodiment of the present invention.

[0040] Figure 2 Pt-Re / Al prepared in Example 1 2 O 3 XRD patterns of the catalysts.

[0041] Figure 3 Pt-Re / Al prepared in Example 1 2 O 3 Thermal catalytic performance diagram of methane conversion rate in methane dry reforming reaction of catalyst.

[0042] Figure 4 Pt-Re / Al prepared in Example 1 2 O 3 H in the dry reforming of methane over the catalyst 2 The curve of the ratio of CO / CO changing with temperature. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0044] The methods used in the following examples, unless otherwise specified, are all conventional methods, carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial sources.

[0045] The waste Pt-Re / Al used in the following examples 2 O 3 The main component of reforming catalyst is Al 2 O 3 , the content is 95.52%, and the active metal component of the catalyst is 0.25% PtO 2 , 0.46% ReO 4 - , 1.61% Cl, 0.71% SO 3 , 0.42% Fe 2 O 3 , 0.17% TiO 2 , 0.08%GaO 3 .

[0046] The calculation formula for the extraction efficiency of each metal in the following examples is as follows:

[0047]

[0048] In this formula, M represents metal (Pt, Re, Al), E represents extraction efficiency, and C 0 is the initial concentration of the metal in the leachate, C 1 is the concentration of metal in the extraction solution, V 0 refers to the volume of the original solution, and V refers to the volume of the extraction solution.

[0049] Example 1

[0050] According to Figure 1 The flow chart shown is used to recover platinum rhenium and prepare Pt-Re / Al 2 O 3 Catalyst, the specific steps are as follows:

[0051] (1) Waste Pt-Re / Al 2 O 3 The reforming catalyst was calcined at 400 °C for 4 h and then heated to 2.0 M HCl + 5% H 2 O 2 The solution was added to the calcined sample at a liquid-solid ratio of 5g:1mL, leached at 120℃ for 3h, and the leachate was collected. 1000ml of the waste reforming catalyst leachate was measured, in which the concentration of Pt ions was 100ppm, the concentration of Re ions was 200ppm, and the concentration of Al ions was 900ppm. 30% N235 + 5% TBP extractant was prepared, and the pH was adjusted with 2mol / L HCl solution and 4mol / L NaOH solution. When the pH was 1, 2, 3, 5, and 7, respectively, O:A = 1:1 was used for extraction, and the extraction time was controlled at 5min to obtain an organic phase containing platinum rhenium. At pH = 2, the extraction rate of platinum rhenium was the highest, and the specific data are shown in Table 1.

[0052] (2) Prepare 20% ammonia solution to back-extract the organic phase after extraction. The back-extraction time is 5 min, O:A=1.5:1, and obtain a platinum-rhenium mixed solution through a separatory funnel under the condition of pH=2. The mass ratio of platinum-rhenium in the mixed solution is Pt:Re=1:2.

[0053] (3) Take 100 ml of the platinum-rhenium mixture and weigh 5 g of γ-Al 2 O 3 The carrier was placed in a beaker, the temperature was set to 80°C on the thermostatic stirrer, and stirred for 9 hours. The stirred product was placed in a thermostatic drying oven for drying for 12 hours, the temperature was set to 80°C, and the dried product was ground in a mortar for 30 minutes. It was placed in a muffle furnace for roasting, the temperature was set to 400°C, the insulation time was 3 hours, and the heating rate was 5°C / min.

[0054] (4) The calcined product was placed in a tube furnace under H 2 Calcination was carried out under H 2 The flow rate was 30 sccm, the temperature was set to 400 °C, the holding time was 3 h, and the heating rate was 5 °C / min. The calcined product was ground for 30 min to obtain Pt-Re / Al 2 O 3 Catalyst (0.2wt% Pt, 0.4wt% Re, 99.94wt% γ-Al 2 O 3 vector).

[0055] In this embodiment, when 30% N235 + 5% TBP composite extractant is used to extract platinum-rhenium at different pH values ​​(1, 2, 3, 5, 7), when pH = 2, O:A = 1:1, and the extraction time is 5 min, the co-extraction rate of platinum-rhenium is as high as 99.99%, and the co-extraction is the highest; when 20% ammonia water is used for stripping, O:A = 1.5:1, and the stripping time is 5 min, the stripping rate is as high as 99.99%, and Pt:Re in the platinum-rhenium mixed solution is 1:2, and experiments have found that different extraction pH values ​​do not affect the ratio of Pt to Re in the platinum-rhenium mixed solution.

[0056] Prepared Pt-Re / Al 2 O 3 The XRD pattern of the catalyst is shown in Figure 2 ,from Figure 2 It can be seen that Pt-Re / Al 2 O 3 The catalyst still exhibits the face-centered cubic structure of the platinum lattice. 2 O 3 The rhenium doping did not affect the change of the crystal structure. The main function of rhenium is to reduce or prevent the "agglomeration" of metal components, thereby improving the carbon capacity and stability of the catalyst. The content of platinum and rhenium was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The total mass fraction ratio of platinum to rhenium was 1:2. The above test indicates that Pt-Re / Al 2 O 3 The catalyst was successfully prepared.

[0057] Example 2

[0058] According to Figure 1 The flow chart shown is used to recover platinum rhenium and prepare Pt-Re / Al 2 O 3 Catalyst, the specific steps are as follows:

[0059] (1) Waste Pt-Re / Al 2 O 3 The reforming catalyst was calcined at 400 °C for 4 h and then heated to 2.0 M HCl + 5% H2 O 2 The solution was added to the calcined sample at a liquid-solid ratio of 5g:1mL, leached at 120℃ for 3h, and the leachate was collected. 1000ml of the waste reforming catalyst leachate was measured, in which the concentration of Pt ions was 100ppm, the concentration of Re ions was 200ppm, and the concentration of Al ions was 900ppm. 30% N235 + 10% TBP extractant was prepared, and the pH was adjusted with 2mol / L HCl solution and 4mol / L NaOH solution. When the pH was 1, 2, 3, 5, and 7, O:A = 1:1 was used for extraction, and the extraction time was controlled at 5min to obtain an organic phase containing platinum rhenium. At pH = 2, the extraction rate of platinum rhenium was the highest, and the specific data are shown in Table 1.

[0060] (2) Prepare 20% ammonia solution to back-extract the organic phase after extraction. The back-extraction time is 5 min, O:A=1.5:1, and obtain a platinum-rhenium mixed solution through a separatory funnel under the condition of pH=2. The mass ratio of platinum-rhenium in the mixed solution is Pt:Re=1:2.

[0061] (3) Take 100 ml of the platinum-rhenium mixture and weigh 5 g of γ-Al 2 O 3 The carrier was placed in a beaker, the temperature was set to 80°C on the thermostatic stirrer, and stirred for 9 hours. The stirred product was placed in a thermostatic drying oven for drying for 12 hours, the temperature was set to 80°C, and the dried product was ground in a mortar for 30 minutes. It was placed in a muffle furnace for roasting, the temperature was set to 400°C, the insulation time was 3 hours, and the heating rate was 5°C / min.

[0062] (4) The calcined product was placed in a tube furnace under H 2 Calcination was carried out under H 2 The flow rate was 30 sccm, the temperature was set to 400 °C, the holding time was 3 h, and the heating rate was 5 °C / min. The calcined product was ground for 30 min to obtain Pt-Re / Al 2 O 3 Catalyst (0.2wt% Pt, 0.4wt% Re, 99.94wt% γ-Al 2 O 3 vector).

[0063] In this embodiment, when 30% N235 + 10% TBP composite extractant is used to extract platinum and rhenium at different pH values ​​(1, 2, 3, 5, 7), when pH = 2, O:A = 1:1, and extraction time is 5 min, the extraction rate of platinum is 98.99%, and the extraction rate of rhenium is 97.96%, with the highest co-extraction; Pt:Re = 1:2 in the platinum-rhenium mixed solution, and experiments have found that different extraction pH values ​​do not affect the ratio of Pt to Re in the platinum-rhenium mixed solution.

[0064] Example 3

[0065] According to Figure 1 The flow chart shown is used to recover platinum rhenium and prepare Pt-Re / Al 2 O 3 Catalyst, the specific steps are as follows:

[0066] (1) Waste Pt-Re / Al 2 O 3 The reforming catalyst was calcined at 400 °C for 4 h and then heated to 2.0 M HCl + 5% H 2 O 2 The solution was added to the calcined sample at a liquid-solid ratio of 5g:1mL, leached at 120℃ for 3h, and the leachate was collected. 1000ml of the waste reforming catalyst leachate was measured, in which the concentration of Pt ions was 100ppm, the concentration of Re ions was 200ppm, and the concentration of Al ions was 900ppm. 20% N235 + 10% TBP extractant was prepared, and the pH was adjusted with 2mol / L HCl solution and 4mol / L NaOH solution. When the pH was 1, 2, 3, 5, and 7, respectively, O:A = 1.5:1 was used for extraction, and the extraction time was controlled at 5min to obtain an organic phase containing platinum rhenium. At pH = 3, the extraction rate of platinum rhenium was the highest. The specific data are shown in Table 1.

[0067] (2) Prepare a 20% ammonia solution to back-extract the organic phase after extraction. The back-extraction time is 5 min, O:A=1.5:1, and obtain a platinum-rhenium mixed solution through a separatory funnel under the condition of pH=3. The mass ratio of platinum-rhenium in the mixed solution is Pt:Re=1:1.

[0068] (3) Take 100 ml of the platinum-rhenium mixture and weigh 5 g of γ-Al 2 O 3 The carrier was placed in a beaker, the temperature was set to 80°C on the thermostatic stirrer, and stirred for 9 hours. The stirred product was placed in a thermostatic drying oven for drying for 12 hours, the temperature was set to 80°C, and the dried product was ground in a mortar for 30 minutes. It was placed in a muffle furnace for roasting, the temperature was set to 400°C, the insulation time was 3 hours, and the heating rate was 5°C / min.

[0069] (4) The calcined product was placed in a tube furnace under H 2 Calcination was carried out under H 2 The flow rate was 30 sccm, the temperature was set to 400 °C, the holding time was 3 h, and the heating rate was 5 °C / min. The calcined product was ground for 30 min to obtain Pt-Re / Al 2 O 3 Catalyst (0.2wt% Pt, 0.2wt% Re, 99.96wt% γ-Al2 O 3 vector).

[0070] In this embodiment, when 20% N235 + 10% TBP composite extractant is used to extract platinum and rhenium at different pH (1, 2, 3, 5, 7), when pH = 3, O:A = 1.5:1, and extraction time is 5 min, the extraction rate of platinum is 98.89%, the extraction rate of rhenium is 47.65%, and the co-extraction rate is the highest; Pt:Re = 1:1 in the platinum-rhenium mixed solution, and experiments have found that different extraction pH does not affect the ratio of Pt to Re in the platinum-rhenium mixed solution.

[0071] Example 4

[0072] According to Figure 1 The flow chart shown is used to recover platinum rhenium and prepare Pt-Re / Al 2 O 3 Catalyst, the specific steps are as follows:

[0073] (1) Waste Pt-Re / Al 2 O 3 The reforming catalyst was calcined at 400 °C for 4 h and then heated to 2.0 M HCl + 5% H 2 O 2 The solution was added to the calcined sample at a liquid-solid ratio of 5g:1mL, leached at 120℃ for 3h, and the leachate was collected. 1000ml of the waste reforming catalyst leachate was measured, in which the concentration of Pt ions was 100ppm, the concentration of Re ions was 200ppm, and the concentration of Al ions was 900ppm. 20% N235 + 5% TBP extractant was prepared, and the pH was adjusted with 2mol / L HCl solution and 4mol / L NaOH solution. When the pH was 1, 2, 3, 5, and 7, respectively, O:A = 1.5:1 was used for extraction, and the extraction time was controlled at 10min to obtain an organic phase containing platinum rhenium. The extraction rate of platinum rhenium was the highest under the condition of pH = 3. The specific data are shown in Table 1.

[0074] (2) Prepare a 20% ammonia solution to back-extract the organic phase after extraction. The back-extraction time is 5 min, O:A=1.5:1, and obtain a platinum-rhenium mixed solution through a separatory funnel under the condition of pH=3. The mass ratio of platinum to rhenium in the mixed solution is 1:1.

[0075] (3) Take 100 ml of the platinum-rhenium mixture and weigh 5 g of γ-Al 2 O 3The carrier was placed in a beaker, the temperature was set to 80°C on the thermostatic stirrer, and stirred for 12 hours. The stirred product was placed in a thermostatic drying oven for drying for 12 hours, the temperature was set to 80°C, and the dried product was ground in a mortar for 30 minutes. It was placed in a muffle furnace for roasting, the temperature was set to 400°C, the insulation time was 3 hours, and the heating rate was 5°C / min.

[0076] (4) The calcined product was placed in a tube furnace under H 2 Calcination was carried out under H 2 The flow rate was 30 sccm, the temperature was set to 400 °C, the holding time was 3 h, and the heating rate was 5 °C / min. The calcined product was ground for 30 min to obtain Pt-Re / Al 2 O 3 Catalyst (0.2wt% Pt, 0.2wt% Re, 99.96wt% γ-Al 2 O 3 vector).

[0077] In this embodiment, when 20% N235 + 5% TBP composite extractant is used to extract platinum and rhenium at different pH (1, 2, 3, 5, 7), when pH = 3, O:A = 1.5:1, and extraction time is 10 min, the extraction rate of platinum is 96.76%, the extraction rate of rhenium is 48.13%, and the co-extraction rate is the highest; Pt:Re = 1:1 in the platinum-rhenium mixed solution, and experiments have found that different extraction pH does not affect the ratio of Pt to Re in the platinum-rhenium mixed solution.

[0078] Example 5

[0079] According to Figure 1 The flow chart shown is used to recover platinum rhenium and prepare Pt-Re / Al 2 O 3 Catalyst, the specific steps are as follows:

[0080] (1) Waste Pt-Re / Al 2 O 3 The reforming catalyst was calcined at 400 °C for 4 h and then heated to 2.0 M HCl + 5% H 2 O 2The solution was added to the calcined sample at a liquid-solid ratio of 5g:1mL, leached at 120℃ for 3h, and the leachate was collected. 1000ml of the waste reforming catalyst leachate was measured, in which the concentration of Pt ions was 100ppm, the concentration of Re ions was 200ppm, and the concentration of Al ions was 900ppm. 10% N235 + 5% TBP extractant was prepared, and the pH was adjusted using 2mol / L HCl solution and 4mol / L NaOH solution. The extraction was carried out at O:A = 1.5:1 when the pH was 1, 2, 3, 5, and 7, respectively. The extraction time was controlled at 5min to obtain an organic phase containing platinum-rhenium. The extraction rate of platinum-rhenium was the highest at pH = 5. The specific data are shown in Table 1.

[0081] (2) Prepare 20% ammonia solution to back-extract the organic phase after extraction. The back-extraction time is 5 min, O:A=1.5:1, and obtain a platinum-rhenium mixed solution through a separatory funnel under the condition of pH=5. The mass ratio of platinum-rhenium in the mixed solution is Pt:Re=1:0.5.

[0082] (3) Take 100 ml of the platinum-rhenium mixture and weigh 5 g of γ-Al 2 O 3 The carrier was placed in a beaker, the temperature was set to 80°C on the thermostatic stirrer, and stirred for 12 hours. The stirred product was placed in a thermostatic drying oven for drying for 12 hours, the temperature was set to 80°C, and the dried product was ground in a mortar for 30 minutes. It was placed in a muffle furnace for roasting, the temperature was set to 400°C, the insulation time was 3 hours, and the heating rate was 5°C / min.

[0083] (4) The calcined product was placed in a tube furnace under H 2 Calcination was carried out under H 2 The flow rate was 30 sccm, the temperature was set to 400 °C, the holding time was 3 h, and the heating rate was 5 °C / min. The calcined product was ground for 30 min to obtain Pt-Re / Al 2 O 3 Catalyst (0.2wt% Pt, 0.1wt% Re, 99.97wt% γ-Al 2 O 3 vector).

[0084] In this embodiment, when 10% N235 + 5% TBP composite extractant is used to extract platinum and rhenium at different pH values ​​(1, 2, 3, 5, 7), when pH = 5, O:A = 1.5:1, and extraction time is 5 min, the extraction rate of platinum is 80.45%, the extraction rate of rhenium is 21.75%, and the co-extraction rate is the highest; Pt:Re in the platinum-rhenium mixed solution is 1:0.5, and experiments have found that different extraction pH values ​​do not affect the ratio of Pt to Re in the platinum-rhenium mixed solution.

[0085] Example 6

[0086] According to Figure 1 The flow chart shown is used to recover platinum rhenium and prepare Pt-Re / Al 2 O 3 Catalyst, the specific steps are as follows:

[0087] (1) Waste Pt-Re / Al 2 O 3 The reforming catalyst was calcined at 400 °C for 4 h and then heated to 2.0 M HCl + 5% H 2 O 2 The solution was added to the calcined sample at a liquid-solid ratio of 5g:1mL, leached at 120℃ for 3h, and the leachate was collected. 1000ml of the waste reforming catalyst leachate was measured, in which the concentration of Pt ions was 100ppm, the concentration of Re ions was 200ppm, and the concentration of Al ions was 900ppm. 10% N235 + 10% TBP extractant was prepared, and the pH was adjusted with 2mol / L HCl solution and 4mol / L NaOH solution. When the pH was 1, 2, 3, 5, and 7, respectively, the extraction was carried out with O:A=1.5:1, and the extraction time was controlled at 5min to obtain an organic phase containing platinum rhenium. At pH=5, the recovery rate of platinum rhenium was the highest. The specific data are shown in Table 1.

[0088] (2) Prepare a 10% ammonia solution to back-extract the organic phase after extraction. The back-extraction time is 5 min, O:A=1.5:1, and obtain a platinum-rhenium mixed solution through a separatory funnel under the condition of pH=5. The mass ratio of platinum to rhenium in the mixed solution is 1:0.5.

[0089] (3) Take 100 ml of the platinum-rhenium mixture and weigh 5 g of γ-Al 2 O 3 The carrier was placed in a beaker, the temperature was set to 80°C on the thermostatic stirrer, and stirred for 12 hours. The stirred product was placed in a thermostatic drying oven for drying for 12 hours, the temperature was set to 80°C, and the dried product was ground in a mortar for 30 minutes. It was placed in a muffle furnace for roasting, the temperature was set to 400°C, the insulation time was 3 hours, and the heating rate was 5°C / min.

[0090] (4) The calcined product was placed in a tube furnace under H 2 Calcination was carried out under H 2 The flow rate was 30 sccm, the temperature was set to 400 °C, the holding time was 3 h, and the heating rate was 5 °C / min. The calcined product was ground for 30 min to obtain Pt-Re / Al 2 O 3 Catalyst (0.2wt% Pt, 0.1wt% Re, 99.97wt% γ-Al 2 O 3vector).

[0091] In this embodiment, when 10% N235 + 10% TBP composite extractant is used to extract platinum and rhenium at different pH values ​​(1, 2, 3, 5, 7), when pH = 5, O:A = 1.5:1, and extraction time is 5 min, the extraction rate of platinum is 78.67%, the extraction rate of rhenium is 19.15%, and the co-extraction rate is the highest; Pt:Re in the platinum-rhenium mixed solution is 1:0.5, and experiments have found that different extraction pH values ​​do not affect the ratio of Pt to Re in the platinum-rhenium mixed solution.

[0092] Example 7

[0093] According to Figure 1 The flow chart shown is used to recover platinum rhenium and prepare Pt-Re / Al 2 O 3 Catalyst, compared with Example 1, the O:A ratio and extraction time in step (1), the roasting conditions in step (3) and the calcination conditions in step (4) are adjusted, and the specific steps are as follows:

[0094] (1) Waste Pt-Re / Al 2 O 3 The reforming catalyst was calcined at 400 °C for 4 h and then heated to 2.0 M HCl + 5% H 2 O 2 The solution was added to the calcined sample at a liquid-solid ratio of 5g:1mL, leached at 120°C for 3h, and the leaching solution was collected. 1000ml of the spent reforming catalyst leaching solution was measured, in which the concentration of Pt ions was 100ppm, the concentration of Re ions was 200ppm, and the concentration of Al ions was 900ppm. A composite extractant of 30% N235 + 5% TBP was prepared, and the extraction was performed at O:A = 1.5:1 at a pH of 2. The extraction time was controlled at 10min to obtain an organic phase containing platinum and rhenium.

[0095] (2) Prepare a 20% ammonia solution to back-extract the organic phase after extraction. The back-extraction time is 10 min, O:A=1.5:1, and obtain a platinum-rhenium mixed solution through a separatory funnel under the condition of pH=2. The mass ratio of platinum to rhenium in the mixed solution is 1:2.

[0096] (3) Take 100 ml of the platinum-rhenium mixture and weigh 5 g of γ-Al 2 O 3 The carrier was placed in a beaker, the temperature was set to 80°C on the thermostatic stirrer, and stirred for 12 hours. The stirred product was placed in a thermostatic drying oven for drying for 12 hours, the temperature was set to 60°C, and the dried product was ground in a mortar for 30 minutes. It was placed in a muffle furnace for roasting, the temperature was set to 500°C, the insulation time was 4 hours, and the heating rate was 5°C / min.

[0097] (4) The calcined product was placed in a tube furnace under H 2 Calcination was carried out under H 2 The flow rate was 30 sccm, the temperature was set to 500 °C, the holding time was 4 h, and the heating rate was 5 °C / min. The calcined product was ground in a mortar for 30 min to obtain Pt-Re / Al 2 O 3 Catalyst (0.2wt% Pt, 0.4wt% Re, 99.94wt% γ-Al 2 O 3 vector).

[0098] Example 8

[0099] According to Figure 1 The flow chart shown is used to recover platinum rhenium and prepare Pt-Re / Al 2 O 3 Catalyst, compared with Example 1, the O:A ratio and extraction time in step (1), the roasting conditions in step (3) and the calcination conditions in step (4) are adjusted, and the specific steps are as follows:

[0100] (1) Waste Pt-Re / Al 2 O 3 The reforming catalyst was calcined at 400 °C for 4 h and then heated to 2.0 M HCl + 5% H 2 O 2 The solution was added to the calcined sample at a liquid-solid ratio of 5g:1mL, leached at 120°C for 3h, and the leaching solution was collected. 1000ml of the spent reforming catalyst leaching solution was measured, in which the concentration of Pt ions was 100ppm, the concentration of Re ions was 200ppm, and the concentration of Al ions was 900ppm. A composite extractant of 30% N235 + 5% TBP was prepared, and the extraction was performed at O:A = 1.5:1 at a pH of 2. The extraction time was controlled at 15min to obtain an organic phase containing platinum and rhenium.

[0101] (2) Prepare 20% ammonia solution to back-extract the organic phase after extraction. The back-extraction time is 15 min, O:A=1.5:1, and obtain a platinum-rhenium mixed solution through a separatory funnel under the condition of pH=2. The mass ratio of platinum-rhenium in the mixed solution is Pt:Re=1:2.

[0102] (3) Take 100 ml of the platinum-rhenium mixture and weigh 5 g of γ-Al 2 O 3 The carrier was placed in a beaker, the temperature was set to 80°C on the thermostatic stirrer, and stirred for 12 hours. The stirred product was placed in a thermostatic drying oven for drying for 12 hours, the temperature was set to 60°C, and the dried product was ground in a mortar for 30 minutes. It was placed in a muffle furnace for roasting, the temperature was set to 600°C, the holding time was 5 hours, and the heating rate was 5°C / min.

[0103] (4) The calcined product was placed in a tube furnace under H 2 Calcination was carried out under H 2 The flow rate was 30 sccm, the temperature was set to 600 °C, the holding time was 5 h, and the heating rate was 5 °C / min. The calcined product was ground in a mortar for 30 min to obtain Pt-Re / Al 2 O 3 Catalyst (0.2wt% Pt, 0.4wt% Re, 99.94wt% γ-Al 2 O 3 vector).

[0104] Comparative Example 1

[0105] The extractant in Example 1 is replaced by only N235, and the specific steps are as follows:

[0106] (1) Waste Pt-Re / Al 2 O 3 The reforming catalyst was calcined at 400 °C for 4 h and then heated to 2.0 M HCl + 5% H 2 O 2 The solution was added to the calcined sample at a liquid-solid ratio of 5g:1mL, leached at 120℃ for 3h, and the leachate was collected. 1000ml of the waste reforming catalyst leachate was measured, in which the concentration of Pt ions was 100ppm, the concentration of Re ions was 200ppm, and the concentration of Al ions was 900ppm. 30% N235 extractant was prepared, and the pH was adjusted using 2mol / L HCl solution and 4mol / L NaOH solution. The extraction was carried out at O:A=1:1 when the pH was 1, 2, 3, 5, and 7, respectively. The extraction time was controlled at 5min to obtain an organic phase containing platinum-rhenium. At pH=5, the extraction rate of platinum-rhenium was the highest, and the specific data are shown in Table 1.

[0107] (2) Prepare a 20% ammonia solution to back-extract the organic phase after extraction. The back-extraction time is 5 min, O:A=1.5:1, and obtain a platinum-rhenium mixed solution through a separatory funnel under the condition of pH=5. The mass ratio of platinum-rhenium in the mixed solution is Pt:Re=1:1.

[0108] (3) Take 100 ml of the platinum-rhenium mixture and weigh 5 g of γ-Al 2 O 3 Support (0.2wt% Pt, 0.2wt% Re, 99.96wt% γ-Al 2 O 3Carrier). Put it into a beaker, set the temperature to 80℃ on the thermostatic stirrer, and stir for 9h. Put the stirred product into a thermostatic drying oven for drying for 12h, set the temperature to 80℃, and grind the dried product in a mortar for 30min. Put it into a muffle furnace for roasting, set the temperature to 400℃, keep warm for 3h, and heat at a rate of 5℃ / min.

[0109] (4) The calcined product was placed in a tube furnace under H 2 Calcination was carried out under H 2 The flow rate was 30 sccm, the temperature was set to 400 °C, the holding time was 3 h, and the heating rate was 5 °C / min. The calcined product was ground for 30 min to obtain Pt-Re / Al 2 O 3 catalyst.

[0110] Comparative Example 2

[0111] The extractant in Example 1 is replaced by TBP alone, and the specific steps are as follows:

[0112] (1) Waste Pt-Re / Al 2 O 3 The reforming catalyst was calcined at 400 °C for 4 h and then heated to 2.0 M HCl + 5% H 2 O 2 The solution was added to the calcined sample at a liquid-solid ratio of 5g:1mL, leached at 120℃ for 3h, and the leachate was collected. 1000ml of the waste reforming catalyst leachate was measured, in which the concentration of Pt ions was 100ppm, the concentration of Re ions was 200ppm, and the concentration of Al ions was 900ppm. A 5% TBP extractant was prepared, and the pH was adjusted using a 2mol / L HCl solution and a 4mol / L NaOH solution. The extraction was performed at O:A=1:1 when the pH was 1, 2, 3, 5, and 7, respectively. The extraction time was controlled at 5min to obtain an organic phase containing platinum-rhenium. At pH=3, the extraction rate of platinum-rhenium was the highest, and the specific data are shown in Table 1.

[0113] (2) Prepare a 20% ammonia solution to back-extract the organic phase after extraction. The back-extraction time is 5 min, O:A=1.5:1, and obtain a platinum-rhenium mixed solution through a separatory funnel under the condition of pH=3. The mass ratio of platinum-rhenium in the mixed solution is Pt:Re=1:1.

[0114] (3) Take 100 ml of the platinum-rhenium mixture and weigh 5 g of γ-Al 2 O 3 Support (0.2wt% Pt, 0.2wt% Re, 99.96wt% γ-Al 2 O 3Carrier). Put it into a beaker, set the temperature to 80℃ on the thermostatic stirrer, and stir for 9h. Put the stirred product into a thermostatic drying oven for drying for 12h, set the temperature to 80℃, and grind the dried product in a mortar for 30min. Put it into a muffle furnace for roasting, set the temperature to 400℃, keep warm for 3h, and heat at a rate of 5℃ / min.

[0115] (4) The calcined product was placed in a tube furnace under H 2 Calcination was carried out under H 2 The flow rate was 30 sccm, the temperature was set to 400 °C, the holding time was 3 h, and the heating rate was 5 °C / min. The calcined product was ground for 30 min to obtain Pt-Re / Al 2 O 3 catalyst.

[0116] Test Case

[0117] The Pt-Re / Al prepared in the above examples and comparative examples was tested. 2 O 3 The test conditions for the thermal catalytic performance of methane dry reforming of the catalyst are as follows: 200.0 mg of the catalyst is weighed and loaded into a quartz tube, which is then placed in a fixed field reactor for thermal catalytic performance testing. Before the test begins, H 2 After reduction and vacuum treatment, the gas concentration is adjusted to CH 4 :CO 2 :N 2 =1:1:8 ratio into the quartz tube, CH 4 and CO 2 The flow rate is 2ml / min, N 2 The flow rate is 16 ml / min. The thermal catalytic performance of the catalyst was tested at 400°C, 500°C, 600°C, 700°C, 800°C and 850°C.

[0118] At a test temperature of 800 °C, CH 4 The conversion rates are shown in Table 1-2.

[0119] Table 1 Extraction rate and catalyst thermal performance under different extraction systems

[0120] Compound Extraction Agent Pt extraction rate (%) Re extraction rate (%) Pt:Re <![CDATA[CH 4 Conversion rate (%)]]> Example 1 30% N235 + 5% TBP 99.99 99.99 1:2 99.96 Example 2 30% N235 + 10% TBP 98.99 97.96 1:2 96.17 Example 3 20%N235+10%TBP 98.89 47.65 1:1 90.12 Example 4 20%N235+5%TBP 96.76 48.13 1:1 91.07 Example 5 10% N235 + 5% TBP 80.45 21.75 1:0.5 87.41 Example 6 10%N235+10%TBP 78.67 19.15 1:0.5 88.65 Comparative Example 1 30％N235 40.12 41.43 1:1 89.71 Comparative Example 2 5% TBP 38.13 32.04 1:1 89.15

[0121] Table 2 Thermal catalytic performance of different catalysts

[0122] Compound Extraction Agent Pt:Re Calcination temperature (℃) Calcination time (h) <![CDATA[CH 4 Conversion rate (%)]]> Example 1 30% N235 + 5% TBP 1:2 400 3 99.96 Example 7 30%N235+5%TBP 1:2 500 4 98.97 Example 8 30%N235+5%TBP 1:2 600 5 98.65

[0123] As can be seen from Table 1, the platinum-rhenium co-extraction ability of 30% N235 + 5% TBP is stronger than that of single extractant N235 or TBP, and the extraction effect of the composite extractant is the best in the concentration ratio of N235 and TBP. When the mass ratio of platinum to rhenium is controlled at 1:2, the methane conversion rate of the synthesized catalyst is the highest and the thermal catalytic performance is the best. As can be seen from Table 2, the calcination temperature and time of the catalyst have little effect on the performance of the catalyst. Preferably, the calcination temperature is maintained at 400°C and the calcination time is determined to be 3h. The synthesized catalyst has good performance and is low-carbon and environmentally friendly.

[0124] Pt-Re / Al in Example 1 2 O 3 The thermal catalytic performance of the catalyst for methane dry reforming is shown in the figure Figure 3 and Figure 4 As shown. Figure 3 It can be seen that as the temperature increases, CH 4 and CO 2 The conversion rate of CH 4 The conversion rate of CO is as high as 99.99%, and it does not change as the temperature continues to rise, but tends to be stable; 2 The conversion rate is also increasing. When the temperature reaches 800°C, the conversion rate is as high as 98.96% and tends to be stable, and does not change with the increase of temperature. Figure 4 As shown, CO and H 2 The yield of H 2 The ratio of CO is infinitely close to 1.

[0125] It can be seen that the Pt-Re / Al regenerated synthesized by the present invention 2 O 3 The catalyst has good and stable thermal catalytic performance and strong CH 4 and CO 2 conversion performance and carbon fixation performance.

[0126] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, can implement the present invention in a wider range under equivalent parameters, concentrations and conditions. Although the present invention provides specific embodiments, it should be understood that the present invention can be further improved. In a word, according to the principle of the present invention, the application is intended to include any changes, uses or improvements to the present invention, including departing from the disclosed scope in the application and the changes made with conventional techniques known in the art.

Claims

1. A method for recycling a waste reforming catalyst to prepare a methane dry reforming catalyst, comprising the following steps: (1) calcining the spent Pt-Re / Al2O3 reforming catalyst, and after calcination, placing the spent reforming catalyst in a solution consisting of acid, hydrogen peroxide and water for leaching to obtain a spent reforming catalyst leachate containing Pt ions, Re ions and Al ions; (2) co-extracting platinum and rhenium in the waste reforming catalyst leachate with a N235+TBP composite extractant to obtain an organic phase containing platinum and rhenium; (3) stripping the organic phase containing platinum and rhenium with NH3·H2O to obtain a platinum-rhenium mixed solution; (4) adding the γ-Al2O3 carrier to the platinum-rhenium mixed solution and stirring to perform an impregnation treatment, and after the impregnation is completed, drying, grinding and calcining are performed in sequence; (5) The product obtained by the calcination treatment is calcined under a H2 atmosphere to obtain the methane dry reforming catalyst Pt-Re / Al2O3.

2. The method for preparing a methane dry reforming catalyst by recycling a waste reforming catalyst according to claim 1, characterized in that: In step (1), in the calcination step, the temperature is 400° C. and the time is 4 h; In the solution consisting of acid, hydrogen peroxide and water, the concentration of acid is 2.0M and the mass concentration of H2O2 is 5%; In the leaching step, the liquid-to-solid ratio is 5 g:1 mL, the leaching temperature is 120° C., and the leaching time is 3 h.

3. The method for preparing a methane dry reforming catalyst by recycling a waste reforming catalyst according to any one of claims 1 to 2, characterized in that: The N235+TBP composite extractant is composed of N235, TBP and a diluent, and the diluent is preferably petroleum ether; In terms of mass percentage, in the N235+TBP compound extractant, the concentration of the N235 extractant is 10% to 30%, the concentration of the TBP is 5% to 20%, and the concentration of the diluent is 50% to 85%; In the co-extraction step, the co-extraction ratio A / O=1:(1-1.5), and the co-extraction time is 5-20 min; The method further comprises: adjusting the pH of the co-extraction system to 1-7 before the co-extraction.

4. The method for preparing a methane dry reforming catalyst by recycling a waste reforming catalyst according to any one of claims 1 to 3, characterized in that: In terms of mass percentage, the concentration of NH3·H2O is 10% to 20%; In the stripping step, the stripping ratio is A / O=1:(1-1.5), and the stripping time is 5-20 min; After the back extraction, the method further comprises: adjusting the pH of the back extracted system to the pH value of the co-extraction step, and then separating the aqueous phase and the organic phase.

5. The method for preparing a methane dry reforming catalyst by recycling a waste reforming catalyst according to any one of claims 1 to 4, characterized in that: In the platinum-rhenium mixed solution, the mass fraction ratio of platinum to rhenium is 1:(0.5-2); The mass fraction of the γ-Al2O3 carrier in the methane dry reforming catalyst is 80% to 99.97%, preferably 99.94% to 99.97%.

6. The method for preparing a methane dry reforming catalyst by recycling a spent reforming catalyst according to any one of claims 1 to 5, characterized in that: In the impregnation step, the solid-liquid ratio is 1:20, the temperature is 80° C., and the stirring time is 9 h to 12 h; In the drying step, the drying temperature is 50°C to 80°C and the drying time is 12h; In the calcination step, the calcination time is 3 to 5 hours and the calcination temperature is 400° C. to 600° C.

7. The method for preparing a methane dry reforming catalyst by recycling a waste reforming catalyst according to any one of claims 1 to 6, characterized in that: In the calcination step, the H2 flow rate is 30 sccm; In the calcination step, the calcination temperature is 400° C. to 600° C., and the calcination time is 3 to 5 hours.

8. A methane dry reforming catalyst Pt-Re / Al2O3 prepared by the method according to any one of claims 1 to 7.

9. A methane dry reforming method, comprising the following steps: using the methane dry reforming catalyst Pt-Re / Al2O3 as claimed in claim 8 as a catalyst, reacting a mixed gas containing methane and carbon dioxide with the catalyst in a fixed bed reactor.

10. The methane dry reforming method according to claim 9, characterized in that: In the mixed gas, the volume ratio of methane to carbon dioxide is 1:(1-2); The flow rates of methane and carbon dioxide corresponding to each 0.2g of the catalyst are (2-4) ml / min; The reaction temperature is 400-850°C; The mixed gas uses nitrogen or argon as the balance gas, and the volume fractions of methane and carbon dioxide in the mixed gas are both 10% to 20%.

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