阅读说明：本技术 一种3r型二硫化钼催化剂的制备方法 (Preparation method of 3R type molybdenum disulfide catalyst ) 是由 熊昆 许景钫 张海东 龙川 向阳 余林键 张贤明 于 2020-05-22 设计创作，主要内容包括：本发明涉及石油化工催化加氢领域,具体公开了一种3R型二硫化钼催化剂的制备方法,包括以下步骤,利用球磨机将四硫代钼酸铵与无机盐以一定质量比研磨混合；将混合物放入惰性气氛中进行退火处理,退火温度不低于300℃,待反应结束,冷却至室温后,用稀盐酸水溶液溶解洗涤,去除无机盐和杂质,得到3R型二硫化钼催化剂。采用本专利中的技术方案制得的二硫化钼催化剂呈现3R型晶型,且不会向2H晶型转化,相较于2H型晶型的二硫化钼而言,3R型二硫化钼具有更多的不饱和活性位参与加氢反应,因此反应活性要远高于2H型二硫化钼,在对废润滑油进行催化加氢反应时,反应后的油品中甲苯不溶物、残炭、灰分和主要金属元素脱出率更高。(The invention relates to the field of petrochemical catalytic hydrogenation, and particularly discloses a preparation method of a 3R-type molybdenum disulfide catalyst, which comprises the following steps of grinding and mixing ammonium tetrathiomolybdate and inorganic salt in a certain mass ratio by using a ball mill; and (3) putting the mixture into an inert atmosphere for annealing treatment, wherein the annealing temperature is not lower than 300 ℃, after the reaction is finished, cooling to room temperature, dissolving and washing by using a dilute hydrochloric acid aqueous solution, and removing inorganic salts and impurities to obtain the 3R-type molybdenum disulfide catalyst. The molybdenum disulfide catalyst prepared by adopting the technical scheme in the patent presents a 3R type crystal form and cannot be converted to a 2H crystal form, and compared with the molybdenum disulfide of the 2H type crystal form, the 3R type molybdenum disulfide has more unsaturated active sites to participate in hydrogenation reaction, so that the reaction activity is far higher than that of the 2H type molybdenum disulfide, and when the catalytic hydrogenation reaction is carried out on waste lubricating oil, the removal rate of toluene insoluble substances, residual carbon, ash and main metal elements in the oil product after the reaction is higher.)

1. A preparation method of a 3R type molybdenum disulfide catalyst is characterized by comprising the following steps: the method comprises the following steps:

step 1: grinding and mixing ammonium tetrathiomolybdate and inorganic salt by a ball mill, wherein the ball milling time is not less than 6 h;

step 2: and (3) putting the mixture obtained in the step (1) into an inert atmosphere for annealing treatment, wherein the annealing temperature is not lower than 300 ℃, after the reaction is finished, cooling to room temperature, dissolving and washing with a solvent, and drying to obtain the 3R type molybdenum disulfide catalyst.

2. The method for preparing a 3R type molybdenum disulfide catalyst according to claim 1, wherein: the mass ratio of the ammonium tetrathiomolybdate to the inorganic salt in the step 1 is 1: (1-20).

3. The method for preparing a 3R type molybdenum disulfide catalyst according to claim 1, wherein: the inorganic salt in the step 1 is one of potassium chloride, lithium chloride or zinc chloride.

4. The method for preparing a 3R type molybdenum disulfide catalyst as claimed in claim 2, wherein: and the solvent in the step 2 is dilute hydrochloric acid or dilute nitric acid.

5. The preparation method of the 3R type molybdenum disulfide catalyst according to any one of claims 1 to 4, characterized by comprising the following steps: the inert atmosphere in the step 2 is one of nitrogen or argon.

6. The method for preparing a 3R type molybdenum disulfide catalyst according to any one of claim 5, wherein: in the step 2, the annealing temperature is 300-900 ℃, and the reaction time is 1-10 h.

7. The method for preparing a 3R type molybdenum disulfide catalyst according to any one of claim 5, wherein: in the step 2, the annealing temperature is 850-900 ℃, and the reaction time is 1-10 h.

Technical Field

The invention relates to the field of catalytic hydrogenation in petrochemical industry, and particularly relates to a preparation method of a 3R type molybdenum disulfide catalyst.

Background

With the increasing demand of human beings on various resources, the self-sufficiency of important resources is seriously insufficient, and particularly the external dependence of fossil energy rises year by year. According to statistics, the import of Chinese petroleum in 2018 reaches 4.62 hundred million tons, and the formed waste oil is increased continuously. If the catalyst is directly discharged or combusted, not only a great deal of waste of resources is caused, but also great environmental hazard is generated, so that the waste oil recycling technology is developed, and particularly, the catalyst with high activity and high stability is developed for catalyzing hydrogenation to regenerate the waste oil, thereby having important strategic significance for improving the comprehensive utilization efficiency of the waste oil resources and reducing the environmental pollution.

At present, the waste oil hydrogenation catalyst mainly takes molybdenum disulfide as a main component, and unsaturated sites, metal ion vacancies and sulfide ion vacancies generated after vulcanization attract H₂The molecules move to the active center to form Mo-H or S-H intermediate links, which are unstable and tend to provide hydrogen radicals to other compounds to effect hydrogenation. The type and distribution of active sites therefore directly determines the performance of the catalyst. Molybdenum disulfide has three different crystal forms, namely 1T type, 2H type and 3R type. Among them, 2H type is the most easily prepared structure, so the most common crystal form of molybdenum disulfide catalyst in the market is 2H type, due to the limitation of the current process, the crystal form is easily evolved into 2H type stable structure in the process of preparing 3R type structure, and 3R type II with stable structure is difficult to obtainMolybdenum sulfide, so the molybdenum disulfide of 3R type is not found to be used in the catalytic hydrogenation reaction of oil products at present.

Disclosure of Invention

The invention provides a preparation method of a 3R type molybdenum disulfide catalyst, which solves the problem that the 3R type molybdenum disulfide catalyst with a stable structure cannot be obtained by the existing process.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a preparation method of a 3R type molybdenum disulfide catalyst comprises the following steps:

step 1: grinding and mixing ammonium tetrathiomolybdate and inorganic salt by a ball mill, wherein the ball milling time is not less than 6 h;

step 2: and (3) putting the mixture obtained in the step (1) into an inert atmosphere for annealing treatment, wherein the annealing temperature is not lower than 300 ℃, after the reaction is finished, cooling to room temperature, dissolving and washing with a solvent, and drying to obtain the 3R type molybdenum disulfide catalyst.

The technical principle and the effect of the technical scheme are as follows:

1. at present, 3R type molybdenum disulfide is difficult to prepare, so 2H type molybdenum disulfide is usually used in the catalytic hydrogenation reaction of oil products, and the conventional preparation process of 2H type molybdenum disulfide is that a molybdenum precursor and a sulfur precursor are directly synthesized through a hydrothermal reaction, so that the 2H type molybdenum disulfide obtained in such a way has good dispersibility and is beneficial to the catalytic hydrogenation reaction.

Although the 2H type molybdenum disulfide can also be obtained by annealing ammonium tetrathiomolybdate at the temperature of more than 300 ℃, the molybdenum disulfide prepared in such a way is in a block shape, other carriers are generally required to be dispersed and expose more active specific surface to form a supported catalyst, and the carrier of the existing supported catalyst is difficult to dissolve/separate and remove by using a simple method, while the inventor of the present application adds an inorganic salt into the ammonium tetrathiomolybdate in order to obtain the 2H type molybdenum disulfide which has better dispersity and can remove the carrier, and unexpectedly finds that the 3R type molybdenum disulfide is prepared by experiments.

2. The inorganic salt in the scheme is ball-milled with the ammonium tetrathiomolybdate in the step 1, when the ball-milling time exceeds 6 hours, the obtained mixture is sticky in appearance, the reason is that the inorganic salt is coated outside the ammonium tetrathiomolybdate at the moment, and the inorganic salt is used as a crystal template, so that the ammonium tetrathiomolybdate is highly dispersed in the inorganic salt crystal, and during annealing treatment, the microstructure of the inorganic salt is utilized to induce the ammonium tetrathiomolybdate to be decomposed to form a 3R type crystal structure, and the 3R type structure can stably exist and cannot be evolved into a 2H type.

3. In the scheme, after the inorganic salt is washed and dissolved by the solvent in the step 2, the inorganic salt can be quickly separated from the molybdenum disulfide, so that the pore-forming effect is achieved, and the obtained molybdenum disulfide catalyst has a 3R-type structure and a larger specific surface area, so that the number of active sites in the catalytic hydrogenation reaction is increased.

4. Experiments prove that the 3R type molybdenum disulfide obtained in the scheme has better reaction performance compared with 2H type molybdenum disulfide when the waste lubricating oil is subjected to hydrogenation catalytic reaction, and the desorption rate of toluene insoluble substances, carbon residue, ash and main metal elements in an oil product after the reaction is higher, because the 3R type molybdenum disulfide has more unsaturated active sites to participate in the hydrogenation reaction, and the reaction activity is far higher than that of the 2H type molybdenum disulfide.

5. The method for preparing the 3R-type molybdenum disulfide catalyst is simple and easy to implement, safe to operate, suitable for the technical field of catalytic hydrogenation in petrochemical industry, and easy to realize industrialization.

Further, the mass ratio of ammonium tetrathiomolybdate to inorganic salt in the step 1 is 1: (1-20).

Has the advantages that: the inorganic salt is thus present in an amount greater than the ammonium tetrathiomolybdate, which allows the inorganic salt to better coat the ammonium tetrathiomolybdate during the ball milling process.

Further, in the step 1, the inorganic salt is one of potassium chloride, lithium chloride and zinc chloride.

Has the advantages that: the potassium chloride, the lithium chloride and the zinc chloride can be dissolved in the solvent, wherein the zinc chloride can be vaporized and evaporated at high temperature, so that the subsequent separation steps are reduced.

Further, the solvent in the step 2 is dilute hydrochloric acid or dilute nitric acid.

Has the advantages that: the solvent adopts dilute hydrochloric acid or dilute nitric acid to dissolve inorganic salt, and simultaneously can remove impurities such as ammonium tetrathiomolybdate which may not be completely reacted and molybdenum oxide which may be generated.

Further, the inert atmosphere in the step 2 is one of nitrogen and argon.

Has the advantages that: the nitrogen and the argon are commonly used inert atmosphere and are easily purchased.

Further, the annealing temperature in the step 2 is 300-900 ℃, and the reaction time is 1-10 h.

Has the advantages that: ammonium tetrathiomolybdate can be fully reacted at the temperature.

Further, the annealing temperature in the step 2 is 800-900 ℃, and the reaction time is 1-10 h.

Has the advantages that: when the material is heated at the temperature, the potassium chloride, the lithium chloride or the zinc chloride are in a molten state, and are better coated outside the ammonium tetrathiomolybdate, and the crystal form of the 3R type molybdenum disulfide formed at the higher temperature is more obvious.

Drawings

FIG. 1 is a scanning electron microscope photograph of molybdenum disulfide type 3R catalyst from example 1;

figure 2 is an XRD pattern of the molybdenum disulfide type 3R catalyst of example 1.

Detailed Description

The following is further detailed by way of specific embodiments:

the parameters of examples 1-18 of a method for preparing a 3R-type molybdenum disulfide catalyst are shown in tables 1-3 below:

table 1 shows the parameters for preparing 3R type molybdenum disulfide catalyst in examples 1-6

Table 2 shows the parameters for preparing 3R type molybdenum disulfide catalyst in examples 7-12

Table 3 shows the parameters for preparing 3R type molybdenum disulfide catalyst in examples 13-18

The following example 1 illustrates a detailed preparation method of a 3R-type molybdenum disulfide catalyst, which comprises the following steps:

step 1: 1g of ammonium tetrathiomolybdate and 10g of potassium chloride are ground and mixed by a ball mill for 8 hours;

step 2: putting the mixture obtained in the step 1 into a nitrogen atmosphere for annealing treatment, wherein the annealing temperature is 900 ℃, the reaction time is 3 hours, after cooling to room temperature, dissolving and washing the mixture by using a dilute hydrochloric acid aqueous solution with the mass concentration not more than 1%, removing potassium chloride and impurities in the solution, and drying the solution to obtain the molybdenum disulfide catalyst (MoS) with the crystal form of 3R₂-3R)。