三氟甲烷/氯化氢气体的分离及三氟甲烷的转化技术研究/STUDY ON THE SEPARATION OF TRIFLUOROMETHANE /HYDROCHLO

2019-01-10 23:24:40

HCl 甲烷 chloride 氯化氢 CHF3



为了采用焚烧法处理三氟甲烷温室气体,首先需要将其与氯化氢气体进行分离。因此,本文研究了温室气体三氟甲烷与氯化氢气体的吸收分离技术,并探讨了在较温和反应条件下对三氟甲烷进行分解和转化的可能性。论文主要包括如下三部分内容:
首先,测定了三氟甲烷和氯化氢气体在烷烃、氯代烃、醇、酮、醚、酯等几种有机溶剂中的溶解度,比较了这两种气体在不同溶剂中的溶解度差别,讨论了采用溶剂吸收法对其混合气体进行分离的可能性。结果表明,醇类溶剂如正丁醇和甘油对氯化氢具有较高溶解度,在较高的温度下又容易解吸,而且对低压下三氟甲烷的溶解度极低,尤其是甘油基本上不溶解三氟甲烷,使之有可能作为水吸收剂的替代溶剂用于氯化氢和三氟甲烷的分离,以大大降低吸收液对设备的腐蚀性。
其次,测定了氯化氢气体在不同浓度的盐酸、氯化铝、氯化锌、氯化钛、硫酸氧钛、氯化锡和氯化钙等几种盐溶液中的溶解度,并测定了氯化氢气体在氯化钙和氯化锡溶液中,不同起始浓度下氯化氢的吸收速率,比较了各种盐溶液对氯化氢气体的溶解度以及压力由0.8MPa降至0.2MPa时氯化氢的解吸效率,探讨了对该混合气体进行吸收分离的可行性。结果表明,氯化钙盐溶液有可能作为水的替代溶剂用于三氟甲烷和氯化氢气体的吸收分离,因为盐的存在一方面可以进一步降低三氟甲烷在水中的溶解度,另一方面,还可以降低溶剂中水的分压,从而有助于降低解吸氯化氢中的含水量,而且氯化钙的价格便宜,原料易得。
最后,研究了三氟甲烷在γ-Al2O3/ZnCl2催化剂和柱状活性炭/ZnO催化剂表面的水解动力学;探索了在温和化学反应条件下将三氟甲烷转化为具有高附加值化学品的可能性。结果表明:在500℃温度以下,无论是ZnCl2还是ZnO作为催化剂,三氟甲烷的水解率都不高;通过化学反应转化三氟甲烷时,由于三氟甲烷的稳定性,利用常规化学反应转化三氟甲烷的效率很低,目前尚不具备工业推广的价值,但这些研究结果为今后的研究奠定了基础。



In order to treat the greenhouse gas trifluoromethane (CHF3) via incineration process, CHF3 has to be separated from its hydrochloride(HCl) gas mixture. This thesis is focused on the separation technology for the gas mixture of trifluoromethans/hydrochloride by using organic solvent absorption process, and on the study of feasible approaches for the conversion of thrifluoromethane under mild conditions. The thesis is composed of three parts that follows.
Firstly, solubility of CHF3 and HCl in such organic solvents as alkane, chlorinated solvents, alcohol, ketone, ether and ester was measured experimentally, their solubility difference in different solvents was compared, and the feasibility of separating the gas mixture via absorption was discussed. The experimental results show that the alcohol solvents such as n-butanol and glycerol are possibly viable for the separation of CHF3 and HCl and especially the latter, since CHF3 is insoluble in glycerol while HCl is highly soluble and thermal desorptive, meanwhile the corrosivity of organic solution of hydrochloride is much lower than the corresponding aqueous solution.
Secondly, solubility of HCl in such electrolyte solutions as hydrochloric acid, aluminium chloride, zinc chloride, titanium chloride, titanyl sulfate, stannum chloride and calcium chloride of different concentration was measured experimentally, the dissolving rate of HCl in calcium chloride and stannum chloride aqueous solution was determined, and their solubility difference as well as desorption ratio as pressure reduced from 0.8MPa to 0.2MPa were compared, whereby the feasibility of separating the gas mixture via absorption was discussed. The results show that calcium chloride is possibly viable for the separation of CHF3 and HCl, since the presence of salt can not only suppress the solubility of CHF3 but also lower the vapor pressure of water, which is good for reducing the water content of HCl gas. Meanwhile, calcium chloride is cheap and commercially available.
Lastly, hydrolysis performance of CHF3 on the catalyst of γ-Al2O3/ZnCl2 and granular active carbon/ZnO was investigated experimentally. Besides, the possibility of converting CHF3 to some high value-added chemicals under mild conditions was studied. The experimental results show that neither ZnCl2 nor ZnO can catalyze the hydrolysis of CHF3 in a high conversion rate under temperatures below 500℃. In addition, it is very hard to convert CF3H to some high value added chemicals using conventional reaction due to the high stability of CHF3. Therefore, more efficient approaches for converting CF3H to other chemicals need to be explored in the future.