Naphthalene pitch is a kind of asphalt obtained from pure naphthalene or naphthalene homologue through self reaction. Naphthalene pitch has the characteristics of less heteroatom and concentrated molecular weight, which is commonly used to prepare binder asphalt and mesophase pitch with excellent performance.

①萘的分子結(jié)構(gòu)及其共聚物分子結(jié)構(gòu)

① Molecular structure of naphthalene and its copolymer

萘的分子結(jié)構(gòu)

Molecular structure of naphthalene

從萘的價(jià)鍵結(jié)構(gòu)模型看，萘的結(jié)構(gòu)為高度均勻?qū)ΨQ的六元環(huán)分子，其穩(wěn)定性很高，在570℃以下不分解。在500℃以上，高壓下，萘本身可以自身聚合，主要形成以下形式的低聚物，為萘瀝青的主要成分：

According to the valence bond structure model of naphthalene, the structure of naphthalene is a highly uniform and symmetrical six membered ring molecule with high stability and does not decompose below 570 ℃. When the temperature is above 500 ℃, the main component of naphthalene is naphthalene, and the main component is naphthalene

因?yàn)樽跃酆戏磻?yīng)條件比較苛刻，所以萘瀝青制備方法，主要靠陽離子催化聚合，使萘瀝青在較低的溫度下合成，主要包括ALCL3催化和HF/BF3催化。

Because of the harsh self polymerization reaction conditions, the preparation method of naphthalene pitch mainly relies on cationic catalytic polymerization to make naphthalene pitch synthesized at lower temperature, mainly including AlCl3 catalyst and HF / BF3 catalyst.
              

①ALCL3催化法

① AlCl3 catalytic method

在ALcl3的催化作用下，在100℃左右的低溫下，萘就可開始發(fā)生熱縮聚反應(yīng)及分子內(nèi)和分子間的轉(zhuǎn)變。ALCL3催化主要以陽離子聚合為主，可以生成含有環(huán)烷結(jié)構(gòu)的中間體，這種結(jié)構(gòu)正是易于形成流線中間相的結(jié)構(gòu)。所以利用ALCL3催化聚合可以制備萘系中間相瀝青。

Under the catalysis of AlCl 3, the condensation reaction and intramolecular and intermolecular transformations of naphthalene can begin at about 100 ℃. AlCl3 catalyst is mainly cationic polymerization, which can produce intermediates containing naphthenic structure, which is easy to form streamline mesophase structure. Therefore, naphthalene based mesophase pitch can be prepared by AlCl3 catalytic polymerization.

盡管在催化劑ALCL3的作用下，萘可以在較低溫度下發(fā)生聚合反應(yīng)，但由于ALCL3在反應(yīng)過程中以熔融態(tài)形式存在，且在生成的產(chǎn)物中有一定的溶解度，加之所得產(chǎn)物萘瀝青的黏度較大，使催化劑與瀝青產(chǎn)物完全分離非常困難。而殘留的少量ALCL3使瀝青灰分較高，所以影響碳制品的性能。目前濟(jì)寧碳素利用此方法制備中間相瀝青，灰分在400ppm左右。

In addition, the product can be polymerized in the form of CL3 in the presence of the catalyst at a certain degree of temperature due to the high solubility of the product. The residual AlCl3 makes the ash content of asphalt higher, so it affects the performance of carbon products. At present, Jining carbon uses this method to prepare mesophase pitch, and the ash content is about 400 ppm.

②HF/BF3催化法

② HF / BF3 catalytic method

HF是一種質(zhì)子酸，其陰離子酸根F-親核性很強(qiáng)，加之F-的直徑特別小，致使F-緊緊的附著在H+周圍，一方面削弱H+對(duì)C=C雙鍵的親和力，另一方面阻止了其他基團(tuán)與H+的接觸，是反應(yīng)相對(duì)難于進(jìn)行；即使發(fā)生陽離子聚合，也易于使反應(yīng)終止。HF/BF3體系，既有較強(qiáng)的酸性，陰離子BF4-親核性又弱，體積也大，是制備萘瀝青理想的催化劑。

HF is a kind of protonic acid, its anion acid radical f-nucleophilic is very strong, and the diameter of f-is very small, which makes f-tightly adhere to H +, on the one hand, it weakens the affinity of H + to C = C double bond, on the other hand, it prevents other groups from contacting with H +, which is relatively difficult to carry out the reaction; that is, cationic polymerization can also easily terminate the reaction. HF / BF3 system is an ideal catalyst for the preparation of naphthalene pitch because of its strong acidity, weak nucleophilicity and large volume.

經(jīng)過控制合成條件，合成的萘瀝青軟化點(diǎn)不超過90℃，苯不溶物可以為0，這種瀝青是制備優(yōu)良碳材料的前驅(qū)體，可以直接用來做粘結(jié)劑，經(jīng)過處理后，可以制備流動(dòng)性好的中間相瀝青。

After controlling the synthesis conditions, the softening point of the synthesized naphthalene pitch is not more than 90 ℃, and the benzene insoluble substance can be 0. This kind of pitch is the precursor of preparing excellent carbon materials, which can be directly used as binder. After treatment, mesophase pitch with good fluidity can be prepared.

以上就是萘瀝青制備方法的介紹，希望對(duì)大家有所幫助，如您想要了解更多資訊內(nèi)容請(qǐng)點(diǎn)擊網(wǎng)站：精萘http://www.456nba.com。

The above is the introduction of naphthalene asphalt preparation method, hope to help you, if you want to know more about the content, please click the website: refined naphthalene http://www.456nba.com 。