Application and Background of High Purity Hydrogen Chloride
Hydrogen chloride is an important part of the chlorine industry. Most of the HCl in the US, Europe and Japan is produced in the form of by-product HCl. Most of the by-products of HCl recycle in the process system have not entered the market. According to statistics, about 40 processes have produced by-products of hydrogen chloride and there are 110 processes with hydrogen chloride as the raw material.
However, in China, with the rapid development of the chlorine industry, especially the rapid expansion of the scale of the organic chlorine products in the last ten years, the total amount of hydrogen chloride in the by-product has increased year by year. When the process system can not be fully recovered, the by-product hydrogen chloride often enters the hydrochloric acid by the by-product in the water or further refining the high purity hydrogen chloride.
At present, the market of high purity hydrogen chloride is better, but the market supply of hydrochloric acid is oversupplied, and the by-product hydrochloric acid is a cheap way. Therefore, some enterprises will sacrifice the environment for business interests when they sell the by-product hydrogen chloride or hydrochloric acid as a burden, obviously this way is out of date.
At the same time, a large amount of low concentration of waste hydrochloric acid will be discharged during the process of pickling of steel, electroplating and steel structure, and in the process of chemical pharmaceutical and rare earth production. Waste liquid is usually treated by neutralization. After discharging, it not only costs a lot, but also wastes resources. It brings two pollution, and is not conducive to environmental protection and sustainable development of resources and energy. Therefore, it is necessary to recycle waste hydrochloric acid produced in the process of production.
High purity hydrogen chloride is an important material for silicon wafer etching, passivation, epitaxy, gas-phase polishing, gettering and cleaning process in IC production. It can also be applied to metal smelting, optical communication and scientific research. With the development of large-scale integrated circuits, the requirement for the purity of hydrogen chloride is becoming more and more high. In addition to having more than 99.999% purity, the content of impurities is more and more demanding. Especially, we must strictly limit the content of hydrocarbons and carbon oxygen compounds to prevent the formation of C in silicon wafer processing.
In the past, China imported more electronic grade hydrogen chloride from the United States, Japan and other countries, but in recent years, the development of chemical gases needed by China’s electronics industry has made many breakthroughs and developments in technology. Domestic units have successfully developed the related electronic grade hydrogen chloride products, but it is far from the market demand.