Method for synthesizing vinyl chloride by hydrochlorinating acetylene with gold-based nano material catalyst
阅读说明：本技术 一种金基纳米材料催化剂用于乙炔氢氯化合成氯乙烯的方法 (Method for synthesizing vinyl chloride by hydrochlorinating acetylene with gold-based nano material catalyst ) 是由 周杰 王若徐 王广斌 徐思远 李复乔 陈虹宇 郭国庆 王川 苏巍 邱李树石 韩启 于 2021-11-02 设计创作，主要内容包括：本发明涉及一种金基纳米材料催化剂用于乙炔氢氯化合成氯乙烯的方法,本发明属于纳米催化剂技术领域。本发明通过溶质诱导相分离的合成过程,常温下一步合成包裹着金的二氧化硅催化剂,该催化剂形状、直径和尺寸分布均匀,且可以进行扩大生产,是一种简洁、快速、低能耗的合成负载型壳纳米结构催化剂的方法,并在乙炔氢氯化反应中展示出了良好的催化活性。另外,本发明合成的负载型催化剂属于一步法合成,无需经过模板法合成载体后再进行长时间的负载过程。(The invention relates to a method for synthesizing vinyl chloride by hydrochlorinating acetylene by using a gold-based nano material catalyst, belonging to the technical field of nano catalysts. According to the invention, through the synthesis process of solute induced phase separation, the silica catalyst coated with gold is synthesized at normal temperature in one step, the catalyst is uniform in shape, diameter and size distribution, and can be subjected to scale-up production, the method is a simple, rapid and low-energy-consumption method for synthesizing the supported shell nano-structure catalyst, and the catalyst shows good catalytic activity in the hydrochlorination of acetylene. In addition, the synthesized supported catalyst belongs to one-step synthesis, and a long-time supporting process is not needed after a carrier is synthesized by a template method.)
1. A method for using gold-based nano-material catalyst in acetylene hydrochlorination to synthesize vinyl chloride is characterized in that the gold-based nano-material catalyst is used in the reaction for preparing vinyl chloride by fixed bed acetylene hydrochlorination; wherein the gold-based nano material Au @ SiO2The preparation method comprises the following steps:
adding ethanol solution containing 0.4mol/L ammonia and 0.1% hydroxypropyl cellulose by mass into the ethanol solution with volume of 10% and dissolved HAuCl of 1mg/mL under stirring at a speed of more than 500rpm4And 50mmol/L sodium citrate in water; then tetraethoxysilane with the volume of 0.6 percent of that of the ethanol solution is added; standing and reacting for 12 hours;
taking the prepared Au @ SiO2Mixing with active carbon, grinding until the color is uniform, and obtaining the gold-based nano material catalyst.
2. The method for synthesizing vinyl chloride by hydrochlorinating acetylene according to the gold-based nanomaterial catalyst of claim 1, wherein: the gold-based nano material Au @ SiO2The preparation method comprises the following steps: dissolving 100ml ethanol containing 0.4mol/L ammonia and 0.1% hydroxypropyl celluloseThe solution was stirred at 8000G, 10mL of HAuCl dissolved in 1mg/mL was added4And 50mmol/L sodium citrate in water; then 0.6mL of tetraethoxysilane is added; standing and reacting for 12 hours;
taking 200mg of Au @ SiO2Mixing with 400mg of active carbon, and grinding until the color is uniform to obtain the gold-based nano material catalyst.
3. The method for synthesizing vinyl chloride by hydrochlorinating acetylene according to the gold-based nanomaterial catalyst of claim 1, wherein: also includes the product Au @ SiO2Washing with absolute ethyl alcohol and deionized water for multiple times or directly evaporating.
4. The method for synthesizing vinyl chloride by hydrochlorinating acetylene according to any one of claims 1 to 3, wherein:
the method comprises the following specific steps:
(1) when a catalyst is filled in the reaction, padding a layer of quartz cotton with the thickness of 10mm at the middle position of a quartz reaction tube, adding the catalyst and ensuring the catalyst to be flat, and then adding a layer of quartz cotton with the thickness of 10 mm;
(2) before the reaction, 30ml/min N was used2Purge for 30min, then at reaction temperature, at V(C2H2)＝25ml/min，V(HCl)The reaction gas was introduced at a flow rate of 26.3ml/min and maintained for 10min, and N was rapidly replaced2And ensures that the catalyst is in the gas atmosphere of acetylene and hydrogen chloride and then is V(C2H2)/V(HCl)The ratio of 1:1.05 decreased the reaction gas flow rate.
5. The method for synthesizing vinyl chloride by hydrochlorinating acetylene according to the gold-based nanomaterial catalyst of claim 4, wherein: n in step (2)2Purging is carried out at 150 ℃ (5 ℃/min) and the reaction temperature is 180-200 ℃.
Technical Field
The invention belongs to the field of synthesis of nano catalysts, and particularly relates to a preparation method and application of a gold-based nano material for synthesizing vinyl chloride through hydrochlorination of acetylene.
Background
Polyvinyl chloride (PVC) is an important versatile material, widely used in everyday products and industrial applications. Based on the energy structure characteristics of rich coal and lean oil in China, 90% of PVC is produced by an acetylene hydrochlorination method based on coal resources. At present, the catalysts used in China industry are almost mercury-containing catalysts, however, mercury is high in toxicity and easy to sublimate and run off, and great threats are brought to environmental protection and human health. New non-mercury catalysts are therefore a focus of research in this field.
The patent CN202010714053.5 synthesizes a catalyst with a nano-particle size of 50-1000 nm, the reaction is carried out under the conditions that the space velocity of acetylene is 30/H and the HCl/C2H2 is 1.1, the reaction temperature is controlled between 150 ℃ and 200 ℃, and the acetylene conversion rate can reach more than 90%. But the particle size distribution of the synthesized catalyst is not uniform, and the synthesis efficiency is low.
The patent CN202010714000.3 obtains a catalyst with the particle size of 200-400nm by firstly synthesizing a silica template material, then loading an active component on silica and removing a silica substrate. The reaction is carried out under the conditions that the space velocity of acetylene is 30/H and the HCl/C2H2 is 1.1, and the acetylene conversion rate can reach over 90 percent. But the synthesized catalyst has larger particle size and wide particle size distribution range.
Therefore, it is important to find a new synthesis method to synthesize a catalyst with uniform distribution and uniform particle size, and to improve the dispersion of active components and the catalyst efficiency.
Disclosure of Invention
The invention provides a method for synthesizing vinyl chloride by hydrochlorinating acetylene, which reduces the feeding amount and the loading amount of gold, does not need to carry out a long-time loading process after synthesizing a carrier by a template method, can synthesize a supported gold-based nano-material catalyst by a one-step method, and has good particle shape, diameter and size distribution, high catalyst stability, good dispersion degree of active components and good catalyst efficiency.
In order to solve the technical problem of the invention, the technical scheme is as follows: a gold-based nano-material catalyst is used for a method for synthesizing vinyl chloride by acetylene hydrochlorination, and the gold-based nano-material catalyst is used in a reaction for preparing vinyl chloride by fixed bed acetylene hydrochlorination; wherein the gold-based nano material Au @ SiO2The preparation method comprises the following steps:
adding ethanol solution containing 0.4mol/L ammonia and 0.1% hydroxypropyl cellulose by mass into the ethanol solution with volume of 10% and dissolved HAuCl of 1mg/mL under stirring at a speed of more than 500rpm4And 50mmol/L sodium citrate in water; then tetraethoxysilane with the volume of 0.6 percent of that of the ethanol solution is added; standing and reacting for 12 hours;
taking the prepared Au @ SiO2Mixing with active carbon, grinding until the color is uniform, and obtaining the gold-based nano material catalyst.
It is preferable thatThe gold-based nano material Au @ SiO2The preparation method comprises the following steps: 100mL of an ethanol solution containing 0.4mol/L ammonia and 0.1% hydroxypropyl cellulose was added to 10mL of HAuCl dissolved in 1mg/mL while stirring at 8000G4And 50mmol/L sodium citrate in water; then 0.6mL of tetraethoxysilane is added; standing and reacting for 12 hours;
taking 200mg of Au @ SiO2Mixing with 400mg of active carbon, and grinding until the color is uniform to obtain the gold-based nano material catalyst.
Preferably, the product Au @ SiO is also included2Washing with absolute ethyl alcohol and deionized water for multiple times or directly evaporating.
Preferably, the specific steps are as follows:
(1) when a catalyst is filled in the reaction, padding a layer of quartz cotton with the thickness of 10mm at the middle position of a quartz reaction tube, adding the catalyst and ensuring the catalyst to be flat, and then adding a layer of quartz cotton with the thickness of 10 mm;
(2) before the reaction, 30ml/min N was used2Purge for 30min, then at reaction temperature, at V(C2H2)＝25ml/min，V(HCl)The reaction gas was introduced at a flow rate of 26.3ml/min and maintained for 10min, and N was rapidly replaced2And ensures that the catalyst is in the gas atmosphere of acetylene and hydrogen chloride and then is V(C2H2)/V(HCl)The ratio of 1:1.05 decreased the reaction gas flow rate.
Preferably, N in step (2)2Purging is carried out at 150 ℃ (5 ℃/min) and the reaction temperature is 180-200 ℃.
Has the advantages that:
compared with the synthesis process of solid nano particles, the method can start the nucleation and growth of liquid from a liquid phase and control the growth process of the liquid nano particles from bottom to top by the synthesis process of solute induced phase separation, thereby better controlling the shape, the diameter and the size distribution of the particles. The method does not need to carry out a long-time loading process after synthesizing a carrier by a template method, and synthesizes the silica catalyst coated with the noble metal at normal temperature in a next step, the catalyst has uniform shape, diameter and size distribution, can be used for expanding production, and is simple, quick and low in energy consumptionThe method for synthesizing the supported shell nano-structured catalyst shows good catalytic activity in the hydrochlorination reaction of acetylene. 1600mg of catalyst (533mg Au @ SiO)2Mixing with 1067mg of active carbon, grinding until the color is uniform), and reacting at a space velocity of 150h-1，V(C2H2)/V(HCl)Under the condition that the reaction temperature is 180 ℃, the conversion rate of acetylene can reach 95.0 percent, and the selectivity of vinyl chloride is more than 99 percent. The reaction activity of the endothelium-based nano material catalyst is not obviously reduced within 100h, the acetylene conversion rate can still reach 93%, and the catalyst has high stability.
Comparative example 2-2, since the surfactant was polyvinylpyrrolidone, although a more uniform catalyst could be formed, the amount of gold consumed was large, the gold loading was too high, the surfactant was difficult to remove, the catalyst was difficult to separate (requiring a long centrifugation of 20000G), and only a small batch synthesis was possible.
According to the experimental scheme, a TEM image is shown in figure 4, the total amount of liquid drops can be increased by changing the surfactant into hydroxypropyl cellulose and adjusting the amount of the added aqueous solution and the concentration of salt in the aqueous solution, the gold feeding amount and the loading amount are reduced, the Brownian motion influence is weakened by thickening the shell, the gold is easier to separate (8000G can be separated in a short time), the surfactant is easier to remove, a catalyst with lower loading (3 wt.%) is obtained, and the cost is more favorably saved. The single batch synthesis of the protocol of example 2 was expanded by a factor of 150. Is beneficial to expanding the generation and saving the time.
The route of the chloroauric acid addition was changed, (comparative example 2-1) to ethanol in advance, instead (example 2) to the aqueous solution addition. The amount of the chloroauric acid is greatly reduced, and the feeding amount and the loading rate of the gold-containing compound are reduced; (comparative example 2-1) the gold dosage is more than 100 times, the loading amount is high 15 times, the loading amount is unnecessarily high, and the cost of the product is increased. The scheme of the invention (example 2) aims at reducing the loading and loading of gold.
Comparative example 2-1 requires addition of a large amount of surfactant, and is difficult to purify and separate; example 2 the surfactant was changed, the amount used was reduced to 1% and the product could be isolated without high speed centrifugation.
Adding ammonia as a catalyst for the reaction of the silicon dioxide; ammonia was added so that the reaction was carried out under weak alkalinity.
Drawings
The invention will be further explained with reference to the drawings.
FIG. 1 TEM image of silica shell in example 1.
FIG. 2 TEM image of silica shell in comparative example 1-1.
FIG. 3 TEM image of silica shell in comparative examples 1-2.
FIG. 4 Au @ SiO in example 22TEM images of the catalyst.
FIG. 5 Au @ SiO in comparative example 2-12TEM image of the catalyst 1.
FIG. 6 Au @ SiO in comparative example 2-22-2 TEM image of the catalyst.
Detailed Description
Example 1 catalyst preparation
250ul of 4% (w/w) hydroxypropyl cellulose solution was diluted with 740ul of ethanol and then 10ul of 500mmol/L citric acid ethanol solution was added. 50ul of 335mmol/L aqueous sodium hydroxide solution was added rapidly and vortexed for 5 s. The mixed solution was allowed to stand for 1min, and then 6ul of tetraethoxysilane was added in a vortex state. Finally standing for 2h at 30 ℃.
The TEM image is shown in FIG. 1, and the synthesized nano silicon shell has uniform shape and size, large specific surface area and firm shell.
Comparative example 1-1 catalyst preparation
250ul of 4% (w/w) hydroxypropyl cellulose solution was diluted with 740ul of ethanol and then 10ul of 500mmol/L citric acid ethanol solution was added. 100ul of 5mol/L aqueous ammonium hydroxide solution was added rapidly and vortexed for 5 seconds. The mixed solution was allowed to stand for 1min, and then 6ul of tetraethoxysilane was added in a vortex state. And finally standing for 12 hours.
The TEM image is shown in FIG. 2, the synthesized nano silicon shell has non-uniform shape and size, and the shell is easy to break.
Comparative examples 1-2 catalyst preparation
250ul of 4% (w/w) hydroxypropyl cellulose solution was diluted with 740ul of ethanol and then 10ul of 500mmol/L citric acid ethanol solution was added. 50ul of 300mmol/L aqueous sodium hydroxide solution was added rapidly and vortexed for 5 s. The mixed solution was allowed to stand for 1min, and then 6ul of tetraethoxysilane was added in a vortex state. And finally standing for 6 hours.
The TEM image is shown in FIG. 3, compared with the nano silicon shell synthesized in comparative example 1-1, the nano silicon shell synthesized in comparative example 1-1 has uniform shape, smaller size and large specific surface area, but the shell is too soft.
Example 2 catalyst preparation
100mL of an ethanol solution containing 0.4mol/L ammonia and 0.1% hydroxypropyl cellulose was added to 10mL of HAuCl dissolved in 1mg/mL with high-speed 8000g stirring4And 50mmol/L sodium citrate in water. Then 0.6mL of tetraethoxysilane was added. The reaction was allowed to stand for 12 hours. Washing the product with absolute ethyl alcohol and deionized water for many times to obtain the gold-based nano material catalyst.
The TEM image is shown in fig. 4, by changing the surfactant, the total amount of the liquid drop is increased, the gold feeding amount and the loading amount are reduced, the brownian motion influence is weakened by thickening the shell, the brownian motion influence is easier to separate (8000G can separate in a short time), the surfactant is easier to remove, and the catalyst with lower loading (3 wt.%) amount is obtained. Compared with the comparative example 2-2, the single-batch synthesis amount is enlarged by 150 times.
The catalyst is named as Au @ SiO2。
Comparative example 2-1 catalyst preparation
A mixed solution containing 250. mu.L of a 100mg/mL polyvinylpyrrolidone stock solution, 40. mu.L of a 500mmol/L ethanol solution of citric acid and 510. mu.L of ethanol was prepared. With high speed stirring, 200. mu.L of 100mmol/L HAuCl was added4Ethanol solution. Then 200. mu.L-5 mmol/L ammonia solution was added rapidly and vortexed for 10 s. Standing for 5min, and adding 6. mu.L of tetraethoxysilane. The mixture was left at room temperature for 12 hours.
The TEM image is shown in fig. 5, where the shell is easily broken to expose the catalyst inside, which in turn leads to reduction of gold ions.
The catalyst is named as Au @ SiO2-1。
The gold feeding amount of the comparative example 2-1 is more than 100 times, the loading amount is high by 15 times, the high loading amount is unnecessary, and the cost of the product is increased. Comparative example 2-1 requires addition of a large amount of surfactant and is difficult to purify and separate.
Comparative examples 2-2 catalyst preparation
A mixed solution containing 250. mu.L of a 300mg/mL polyvinylpyrrolidone stock solution, 20. mu.L of a 500mmol/L ethanol solution of citric acid and 630. mu.L of ethanol was prepared. With high speed stirring, 100. mu.L of 100mmol/L HAuCl was added4Ethanol solution. Then 100. mu.L of about 5M aqueous ammonia solution was added rapidly, followed by vortexing for 10 s. Standing for 5min, and adding 6. mu.L of tetraethoxysilane. The mixture was left at room temperature for 12 hours.
The TEM image is shown in fig. 6, although a relatively uniform catalyst can be formed, the gold consumption is large, the gold loading is too high, the surfactant is difficult to remove, the catalyst is difficult to separate (requiring a long centrifugation of 20000G), and only a small batch synthesis is possible.
The catalyst is named as Au @ SiO2-2。
Example 3
The method for synthesizing vinyl chloride by hydrochlorinating acetylene according to the gold-based nanomaterial catalyst prepared in the example 2 comprises the following specific steps:
(1) when a catalyst is filled in the reaction, padding a layer of quartz cotton with the thickness of 10mm at the middle position of a quartz reaction tube, adding the catalyst and ensuring the catalyst to be flat, and then adding a layer of quartz cotton with the thickness of 10 mm;
(2) before the reaction, 30ml/min N was used2Purge for 30min, then at reaction temperature, at V(C2H2)＝25ml/min，V(HCl)The reaction gas was introduced at a flow rate of 26.3ml/min and maintained for 10min, and N was rapidly replaced2And ensures that the catalyst is in the gas atmosphere of acetylene and hydrogen chloride and then is V(C2H2)/V(HCl)The ratio of 1:1.05 decreased the reaction gas flow rate.
N in step (2)2Purging is carried out at 150 ℃ (5 ℃/min) and the reaction temperature is 180-200 ℃.
1600mg of catalyst (533mg Au @ SiO)2Mixing with 1067mg of active carbon, and grinding until the color is uniformOne) at a reaction space velocity of 150h-1，V(C2H2)/V(HCl)Under the condition that the reaction temperature is 180 ℃, the conversion rate of acetylene can reach 95.0 percent, and the selectivity of vinyl chloride is more than 99 percent. The reaction activity of the endothelium-based nano material catalyst is not obviously reduced within 100h, the acetylene conversion rate can still reach 93%, and the catalyst has high stability.
The results of the acetylene hydrochlorination activity test are shown in table 1:
TABLE 1 acetylene hydrochlorination Activity test
The invention is not limited to the specific technical solutions described in the above embodiments, and all technical solutions formed by equivalent substitutions are within the scope of the invention as claimed.
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