阅读说明：本技术 一种用于聚氯乙烯无汞化合成的催化剂的制备方法 (Preparation method of catalyst for mercury-free synthesis of polyvinyl chloride ) 是由 杨卫民 白明瓒 丁玉梅 于 2021-06-11 设计创作，主要内容包括：本发明公开了一种用于聚氯乙烯无汞化合成的催化剂的制备方法,步骤包括：第一步、过渡金属盐加入溶剂中制备成均匀混合溶液；第二步、混合溶液中选择性加入含氮物质,第三步、聚丙烯腈中空纤维浸渍到过渡金属混合溶液中,吸附过渡金属及含氮物质,第四步、吸附过渡金属的PAN中空纤维稳定化处理；第五步、吸附过渡金属的PAN中空纤维碳化处理。本发明使用非贵金属铜、铁等储量较大,成本低廉,且环境友好；加入尿素或三聚氰胺等含氮物质引入氮元素,且在DMF或DMSO溶液中的均一性良好；PAN中空纤维自身也提供了氮掺杂,与过渡金属元素形成稳定的共轭结构,提升了催化活性,有更多活性位点；PAN中空纤维在稳定化和碳化处理后表面和内部的微孔,增大比表面积。(The invention discloses a preparation method of a catalyst for mercury-free synthesis of polyvinyl chloride, which comprises the following steps: firstly, adding a transition metal salt into a solvent to prepare a uniform mixed solution; secondly, selectively adding nitrogen-containing substances into the mixed solution, thirdly, dipping the polyacrylonitrile hollow fiber into the transition metal mixed solution to adsorb transition metals and nitrogen-containing substances, and fourthly, stabilizing the PAN hollow fiber adsorbing the transition metals; and fifthly, carbonizing the PAN hollow fiber adsorbing the transition metal. The invention uses non-noble metals such as copper, iron and the like with large reserves, low cost and environmental protection; nitrogen elements are introduced by adding nitrogen-containing substances such as urea or melamine and the like, and the uniformity of the nitrogen elements in a DMF (dimethyl formamide) or DMSO (dimethyl sulfoxide) solution is good; the PAN hollow fiber also provides nitrogen doping, and forms a stable conjugated structure with transition metal elements, so that the catalytic activity is improved, and more active sites are provided; the surface and the inner micropores of the PAN hollow fiber are subjected to stabilization and carbonization treatment, so that the specific surface area is increased.)

1. A preparation method of a catalyst for mercury-free synthesis of polyvinyl chloride is characterized by comprising the following preparation steps:

firstly, adding a transition metal salt into a solvent to prepare a uniform mixed solution, wherein the transition metal salt is well dispersed in the solvent, and catalytic activity centers are uniformly dispersed;

secondly, selectively adding a nitrogen-containing substance into the mixed solution, wherein nitrogen doping provides excellent catalytic activity sites, and the catalytic activity and the reaction efficiency are improved;

step three, soaking polyacrylonitrile hollow fibers into a transition metal mixed solution to adsorb transition metals and nitrogen-containing substances, wherein PAN provides nitrogen-doped catalytic active sites;

fourthly, stabilizing the PAN hollow fiber adsorbing the transition metal;

and fifthly, carbonizing the PAN hollow fiber adsorbing the transition metal.

2. The method for preparing the catalyst for the mercury-free synthesis of polyvinyl chloride according to claim 1, wherein the method comprises the following steps: the transition metal salts in the first step include chlorides and nitrates of copper, iron, cobalt, nickel, and the like.

3. The method for preparing the catalyst for the mercury-free synthesis of polyvinyl chloride according to claim 1, wherein the method comprises the following steps: in the first step, the solvent is DMF or DMSO, etc.

4. The method for preparing the catalyst for the mercury-free synthesis of polyvinyl chloride according to claim 1, wherein the method comprises the following steps: in the second step, the nitrogen-containing substance is urea or melamine, etc.

5. The method for preparing the catalyst for the mercury-free synthesis of polyvinyl chloride according to claim 1, wherein the method comprises the following steps: the fourth step is that the PAN hollow fiber stabilizing treatment for adsorbing transition metal comprises the following specific steps: firstly, putting the PAN hollow fiber adsorbing the transition metal salt into a heating furnace, and introducing oxygen or air; next, the mixture is heated to 150 ℃ and 300 ℃ for 1-3 hours.

6. The method for preparing the catalyst for the mercury-free synthesis of polyvinyl chloride according to claim 1, wherein the method comprises the following steps: the fifth step is that the PAN hollow fiber adsorbing transition metal is carbonized, and the specific steps are as follows: firstly, introducing inert gases such as argon or nitrogen and the like; secondly, heating to 600-1000 ℃ to completely carbonize the carbon.

Technical Field

The invention relates to the field of polyvinyl chloride (PVC) synthesis, and discloses a catalyst for loading non-noble metal hollow Polyacrylonitrile (PAN) fibers in the PVC synthesis industry.

Background

The monomer vinyl chloride of polyvinyl chloride (PVC) can be prepared from ethylene or acetylene as a raw material. Different from European and American countries, natural gas resources are deficient in China, and coal resources are abundant, so that the popularization of the process for producing vinyl chloride by the acetylene method becomes a main mode for preparing PVC monomers. At present, the catalyst widely used in the acetylene method is mercuric chloride, which not only contains harmful metallic element mercury, but also has serious mercury element loss in the production process, thus leading to the waste of a large amount of mercury metallic catalysts. One part of mercury remains in the PVC resin product, and the other part is discharged into the environment, which causes serious harm to human health and ecological environment. Therefore, the seeking of a mercury-free catalysis, high-efficiency and low-cost production method is particularly important for the current domestic PVC industry.

At present, the mercury-free production method in the PVC industry mainly utilizes mercury-free catalysts, including noble metal catalysts, non-noble metal catalysts and the like. Noble metal catalysts have high catalytic activity and stability, such as gold chloride, but are expensive, scarce in reserves, increase the cost of PVC production, and are therefore difficult to use on a large scale in the PVC industry. Non-noble metal catalysts, such as copper chloride and the like, have large reserves, low cost and small harm to the environment, show a great advantage, but the proportioning and preparation links of the copper chloride catalyst are complex, and the catalytic activity and the stability of the copper chloride catalyst have certain difference from those of noble metal catalysts.

The invention patent of application No. 201810682086.9 discloses a novel CuCl₂And pyrrolidone as active component, and soaking the active component and the mixed water solution in active carbon, and drying to obtain the copper-based catalyst. But the used organic matters are difficult to treat, the operation is complex, the cost is higher, and the environmental pollution is easy to cause.

The invention patent with application number 201710174566.X discloses CuCl₂Dissolving the active component and amide solvent in water to prepare a mixed solution, soaking active carbon in the mixed solution, and drying the obtained catalyst. The catalyst utilizes CuCl₂The synergistic effect of the catalyst and the amide solvent enhances the adsorption capacity of the catalyst on acetylene and hydrogen chloride gas, and the amide solvent is an aprotic high-polarity solvent, has a polarization effect on acetylene, and increases the reaction efficiency. But the catalyst has short service life and does not meet the requirement of large-scale industrial production.

Application No. 201610882150.9, the invention patent proposes a catalyst which is prepared by using copper salt, ammonium salt and phosphoric acid or copper salt, ammonium salt and phosphate as active components, impregnating the active components on an active carbon carrier and drying the active carbon carrier. Ammonium salt (NH) added to the catalyst₄Cl) has the effect of enhancing the stability of the copper-based catalyst, phosphoric acid or phosphoric acid salts (NH)₄H₂PO₄) The reactivity at low temperature is improved. But the catalyst component proportion is complex, and the control is difficult in the large-scale industrial production process, which causes inconvenience.

Therefore, aiming at the further improvement of the mercury-free non-noble metal catalyst, the catalytic activity and the stability of the catalyst are improved, the proportion and the preparation method of the catalyst are simplified, and the catalyst has a great promotion effect on the development of the PVC industry.

Disclosure of Invention

The invention provides a Polyacrylonitrile (PAN) hollow fiber supported non-noble metal catalyst aiming at the defects of the catalysts. The catalyst adopts Polyacrylonitrile (PAN) hollow fiber to fix transition metal salt, such as copper chloride, ferric chloride, cobalt chloride and the like, as a novel catalyst in the PVC preparation process. The catalyst is cost-saving, environment-friendly, high in catalytic activity and strong in stability.

The invention provides a preparation method of a catalyst for mercury-free synthesis of polyvinyl chloride, which comprises the following steps:

firstly, adding a transition metal salt into a solvent to prepare a uniform mixed solution, wherein the transition metal salt is well dispersed in the solvent, and catalytic activity centers are uniformly dispersed;

secondly, selectively adding a nitrogen-containing substance into the mixed solution, wherein nitrogen doping provides excellent catalytic activity sites, and the catalytic activity and the reaction efficiency are improved;

step three, soaking Polyacrylonitrile (PAN) hollow fibers into a transition metal mixed solution to adsorb transition metals and nitrogen-containing substances, wherein PAN provides nitrogen-doped catalytic active sites;

fourthly, stabilizing the PAN hollow fiber adsorbing the transition metal;

and fifthly, carbonizing the PAN hollow fiber adsorbing the transition metal.

As a further improvement of the present invention, the transition metal salt in the first step includes chlorides and nitrates of copper (Cu), iron (Fe), cobalt (Co), nickel (Ni), and the like.

As a further improvement of the invention, in the first step, the solvent is DMF or DMSO, etc.

As a further improvement of the invention, in the second step, the nitrogen-containing substance is urea or melamine.

As a further improvement of the present invention, the fourth step of the stabilization treatment of the transition metal-adsorbed PAN hollow fiber comprises the specific steps of:

firstly, putting the PAN hollow fiber adsorbing the transition metal salt into a heating furnace, and introducing oxygen or air;

next, the mixture is heated to 150 ℃ and 300 ℃ for 1-3 hours.

As a further improvement of the present invention, in the fifth step, the transition metal-adsorbed PAN hollow fiber is carbonized by:

firstly, introducing inert gases such as argon or nitrogen and the like;

secondly, heating to 600-1000 ℃ to completely carbonize the carbon.

Compared with other catalysts, the polyvinyl chloride catalyst prepared by fixing non-noble metal by polyacrylonitrile hollow fiber has the advantages that the used non-noble metal such as copper, iron and the like has larger reserves, low cost and environmental friendliness; adding nitrogen-containing substances such as urea or melamine and the like to introduce nitrogen elements, and ensuring good uniformity in a DMF or DMSO solution so that the active center of the catalyst is uniformly dispersed on the PAN; the PAN hollow fiber also provides nitrogen doping, and forms a stable conjugated structure with transition metal elements, so that the stability and catalytic activity of the catalyst are improved; the PAN hollow fiber loses hydrogen elements and the like after stabilization and carbonization treatment, micropores of about 2nm are generated on the surface and inside, and the specific surface area of the PAN hollow fiber is greatly improved, so that the catalyst has more active sites compared with other catalyst carriers such as active carbon and the like. The novel catalyst disclosed by the invention can reduce the production cost of PVC, improves the production efficiency of PVC, is environment-friendly, and is beneficial to large-scale industrial production of PVC.

Detailed Description

The present invention is described in further detail below with reference to specific examples.

The invention provides a catalyst for preparing polyvinyl chloride by fixing non-noble metal by polyacrylonitrile hollow fiber, and a preparation method of the catalyst for mercury-free synthesis of polyvinyl chloride, which comprises the following preparation steps: firstly, adding a transition metal salt into a solvent to prepare a uniform mixed solution;

secondly, adding a nitrogen-containing substance into the mixed solution;

step three, soaking Polyacrylonitrile (PAN) hollow fibers into a transition metal mixed solution to adsorb transition metals and nitrogen-containing substances;

fourthly, stabilizing the PAN hollow fiber adsorbing the transition metal;

and fifthly, carbonizing the PAN hollow fiber adsorbing the transition metal.

Further, the solvent in the first step is DMF or DMSO, etc.

Further, the transition metal salt in the first step includes chlorides and nitrates of copper (Cu), iron (Fe), cobalt (Co), nickel (Ni), and the like.

Furthermore, in the second step, the nitrogen-containing substance is urea or melamine, etc.

Further, the fourth step is a specific step of the transition metal adsorbed PAN hollow fiber stabilization treatment:

firstly, adding PAN hollow fiber adsorbing transition metal salt into a heating furnace, and introducing oxygen or air; next, the mixture is heated to 150 ℃ and 300 ℃ for 1-3 hours.

Further, the fifth step is a step of carbonizing the transition metal-adsorbed PAN hollow fiber, which comprises:

firstly, introducing inert gases such as argon or nitrogen and the like;

secondly, heating to 600-1000 ℃ to completely carbonize the carbon.