混合氯硅烷酸性水解研究

发布时间：2018-05-15 13:57

本文选题：多晶硅 + 混合氯硅烷　；参考：《昆明理工大学》2016年硕士论文

【摘要】：改良西门子法多晶硅生产过程中的三氯氢硅合成、三氯氢硅的精馏提纯、三氯氢硅还原和冷(热)氢化工序都会不可避免有氯硅烷残液和废气产生。氯硅烷残液和废气主要成分是SiCl4、SiHCl3、SiH2Cl2和HC1,目前国内大部分多晶硅厂都采用碱液淋洗工艺,将氯硅烷残液和废气的无害化处理,由于产生的固废成分复杂,难以资源化利用,造成了资源浪费。国内多晶硅生产过程中产生的氯硅烷残液和废气的处理问题已成为限制多晶硅行业发展的瓶颈之一。针对这些问题,本文提出混合氯硅烷在盐酸中水解同时获得二氧化硅和浓盐酸(或HCl)的方法,以实现氯硅烷残液和废气的资源化。通过研究氯硅烷残液在水或高浓度盐酸中水解的残液量、水解剂(水或盐酸)用量、最终盐酸浓度、产物二氧化硅浓度、水解体系温度等影响因素对水解反应及水解液胶凝时间的影响,并获得水解液胶凝时间的控制方法。随着最终盐酸浓度增加、水解产物二氧化硅浓度增加以及水解反应温度升高都会使得水解液胶凝时间缩短；水解用水(或盐酸)量与残液量的比例减小,同样会导致水解液胶凝时间缩短；在混合氯硅烷酸性水解过程中,硅酸聚合是必然的,而水解液的胶凝是可以控制的,可以通过调整残液和水(或盐酸量和浓度)的比例,进而控制残液水解产生的盐酸浓度、二氧化硅浓度和温度,来控制水解液胶凝时间。结合水解产物气体定性分析以及水解产物二氧化硅红外光谱分析结果,提出混合氯硅烷的水解机理和水解液的胶凝机理：混合氯硅烷在强酸条件下水解,SiCl4水解生成了原硅酸(Si(OH)4),在强酸条件下Si—-H键水解缓慢,SiHCl3和SiH2Cl2水解生成原硅酸(Si(OH)4)和含Si—-H键硅酸(HSi(OH)3和H2Si(OH)2),氯硅烷残液水解同时产生了盐酸,原硅酸、含Si—H键硅酸和盐酸的同时存在,促使原硅酸发生羟联聚合反应,极易发生胶凝,使水解液失去流动性,随着聚合、胶凝过程的进行,Si—H键也进入凝胶中,但Si—H键水解仍在缓慢进行。结合混合氯硅烷酸性水解机理、水解液胶凝机理分析以及通过使用X射线衍射光谱仪、红外光谱仪、扫描电镜、粒度分析仪等对水解产物二氧化硅的结构及微观形态特征研究发现：混合氯硅烷酸性水解产物二氧化硅为无规则三维网状结构的非晶态物质,二氧化硅内部是硅原子和氧原子以三维网状结构的形式构成,而表面有大量的Si—OH和Si—H键存在,同时,羟基上会有大量的氢键结合水；混合氯硅烷酸性水解产物二氧化硅的初始粒径较小(小于5微米),为球状小颗粒,团聚后呈不规则的多孔块状,粒径为1～120μm。研究通过对混合氯硅烷水解产物二氧化硅干样和湿样的亲水性、与水、盐酸和碱的反应性和酸碱性测试,以及二氧化硅样品的干燥、煅烧实验和热重-质谱分析,结果表明：二氧化硅干样和湿样在蒸馏水中表现为亲水性,而在盐酸中表现为疏水性,二氧化硅与水和盐酸混合会有H2缓慢释放,碱性条件可以促进Si—H键水解,羟联聚硅酸在水中会释放酸性基团,使水溶液呈强酸性。105℃干燥可以去除二氧化硅中大部分的自由水,但因其二氧化硅的小粒径、多孔结构导致其有较强的吸附性和二氧化硅表面大量羟基的存在导致其亲水性,干燥完成后,与空气接触,仍会吸附空气中的水分；高温可以将二氧化硅中Si—-OH转变为Si—O—Si基团,减少二氧化硅表面羟基,使得二氧化硅表面吸水性降低,只有在900～1000℃才能将二氧化硅表面的羟基全部驱除,当温度在1063-1300℃时,二氧化硅由非晶态向晶态转变,失去非晶态活性；二氧化硅中Si—H键热稳定性较好,从161.1。C开始热解释放H2,996.5℃才热解完全；由于氯硅烷残液强酸水解产物二氧化硅为羟联聚硅酸,羟联聚硅酸结合了氯化氢,直接水洗及105℃干燥过程无法将其全部去除,会大量残留在二氧化硅中,高温才能缓慢释放。混合氯硅烷在盐酸中水解同时获得二氧化硅和浓盐酸(或氯化氢气体),实现氯硅烷残液和废气的无害化和资源化,减小后续废水处理工序的处理压力,改变了现有氯硅烷废物处理过程中只投入不产出的局面。混合氯硅烷酸性水解过程机理研究为氯硅烷废气和残液浓盐酸水解制备超细二氧化硅并副产浓盐酸(或氯化氢气体)提供理论基础,同时,水解产物二氧化硅的特性研究为二氧化硅产品的定位及后处理提供依据。
[Abstract]:Trichlorosilane synthesis, distillation and purification of trichlorosilane, trichlorosilane reduction and cold (hot) hydrogenation will inevitably produce chlorosilane residue and waste gas. The main components of chlorosilane residue and waste gas are SiCl4, SiHCl3, SiH2Cl2 and HC1. Most of the polysilicon plants in China use alkaline solution at present. The harmless treatment of chlorosilane residue and waste gas by leaching process has caused a waste of resources because of the complex solid waste components produced and difficult to utilize. The treatment of chlorosilane residue and waste gas produced in the production process of polysilicon in China has become one of the bottlenecks to restrict the development of polysilicon industry. The method of hydrolysis of silica and concentrated hydrochloric acid (or HCl) in hydrochloric hydrochloric acid to realize the resource of chlorosilane residue and waste gas. By studying the amount of residue hydrolysate in water or high concentration hydrochloric acid, the amount of hydrolysate (water or hydrochloric acid), the final concentration of hydrochloric acid, the concentration of silica, the temperature of the hydrolysate system, and the temperature of the hydrolysate system. The influence factors such as the hydrolysis reaction and the gelation time of the hydrolysate and the control method of the gelation time of the hydrolysate are obtained. With the increase of the concentration of the final hydrochloric acid, the increase of silica concentration and the increase of the hydrolysis reaction temperature will shorten the gelation time of the hydrolysate, and the amount of water (or hydrochloric acid) of the hydrolysate and the amount of the residual liquid can be reduced. Small, also leads to the shortened gelation time of the hydrolysate; in the process of acid hydrolysis of mixed chlorosilane, the polymerization of silicic acid is inevitable and the gelation of the hydrolysate can be controlled. The concentration of hydrochloric acid produced by the hydrolysis of residual liquid and hydrochloric acid can be controlled by adjusting the proportion of the residual liquid and water (or the amount and concentration of hydrochloric acid), and the concentration and temperature of silicon dioxide are controlled to control the concentration of the SiO2 and the temperature. The hydrolysis mechanism of the mixed chlorosilane and the gelation mechanism of the hydrolysate are proposed by the qualitative analysis of the hydrolysate and the analysis of the silica fir spectrum of the hydrolysate. The hydrolysis of mixed chlorosilane under the condition of strong acid, and the hydrolysis of SiCl4 (Si (OH) 4) by the hydrolysis of the mixed chlorosilane, and the hydrolysis of Si -H under the strong acid condition Slowly, SiHCl3 and SiH2Cl2 hydrolyzed to produce the original silicic acid (Si (OH) 4) and Si - -H bond silicic acid (HSi (OH) 3 and H2Si (OH) 2). Chlorosilane residue hydrolyzed to produce hydrochloric acid simultaneously. The silicic acid, containing Si H bond silicic acid and hydrochloric acid, resulted in the hydroxyl polymerization of the silicic acid, which was very easy to be cementitious, so that the hydrolysate lost its fluidity, with polymerization and gelation. The process is carried out, the Si - H bond is also entered into the gel, but the hydrolysis of Si - H bond is still slow. Combining the acid hydrolysis mechanism of the mixed chlorosilane, the analysis of the gelation mechanism of the hydrolysate and the study of the structure and microstructure of the hydrolysate silicon dioxide by using the X ray diffraction spectrometer, the infrared spectrometer, the scanning electron microscope, the particle size analyzer and so on It is found that the acid hydrolysate of mixed chlorosilane is a amorphous material of irregular three-dimensional network structure, and silicon atoms and oxygen atoms are formed in the form of a three-dimensional network, while a large number of Si - OH and Si - H bonds exist on the surface, and a large number of hydrogen bond binding water in the hydroxyl group; and the acidity of mixed chlorosilane. The initial particle size of the hydrolysate is smaller (less than 5 microns), and it is a small spherical particle with a irregular porous block. The particle size is 1~120 M., and the reaction and acid-base test with water, hydrochloric acid and alkali, as well as the dry of silica samples, are studied by the particle size of 1~120 mu. The results of dryness, calcining and TG MS analysis show that silica dry and wet samples are hydrophilic in distilled water, but hydrophobicity in hydrochloric acid. The mixture of silica and water and hydrochloric acid will release H2 slowly, alkaline conditions can promote the hydrolysis of Si H bonds, and hydroxyl polysilicic acid will release acid groups in water and make water soluble. A strong acid.105 C drying can remove most of the free water in silicon dioxide, but because of the small size of silicon dioxide, the porous structure leads to its strong adsorption and the presence of a large number of hydroxyl groups on the surface of silicon dioxide to lead to its hydrophilicity. After the drying, it will still adsorb the moisture in the air with the air, and the high temperature can be two. Si - -OH in silicon oxide is transformed into Si - O - Si group, reducing the hydroxyl group on the surface of silicon dioxide, reducing the surface water absorption of silicon dioxide. Only at 900~1000 degrees C, the hydroxyl groups on the silica surface can be removed completely. When the temperature is at 1063-1300, the silicon dioxide is transformed from amorphous to crystalline, and the amorphous activity of silica is lost; Si in silica The thermal stability of the H bond is good, and the pyrolysis is complete from the pyrolysis of 161.1.C to release H2996.5 C from the beginning of pyrolysis. The silica is hydroxyl polysilicic acid, the hydroxyl polysilicic acid is combined with hydrogen chloride, and the process of direct water washing and 105 DEG C drying can not be completely removed, and the high temperature can be slow to be slow. Mixed chlorosilane is hydrolyzed in hydrochloric acid to obtain silica and concentrated hydrochloric acid (or hydrogen chloride) to realize the innocuity and resource of chlorosilane residue and waste gas, reduce the treatment pressure of subsequent wastewater treatment process, and change the situation that the existing chlorosilane waste is only input-output. The study of process mechanism provides a theoretical basis for the preparation of superfine silica and by-product of concentrated hydrochloric acid (or hydrogen chloride) by the hydrolysis of chlorosilane and concentrated hydrochloric acid. Meanwhile, the study of the properties of the hydrolysate silicon dioxide provides the basis for the positioning and post-processing of silica products.

【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X76

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