合成NaY型沸石的CO_(2)吸附特性

CO_(2) adsorption characteristics of synthesized NaY zeolite

沸石类CO_(2)吸附剂具有操作能耗低、对设备的腐蚀性小、循环性能稳定等优点,但存在气体吸附容量相对较小的不足。为了获取高效的沸石CO_(2)吸附剂,需要采用先进合成方法提高沸石类吸附剂的CO_(2)捕集能力以克服其吸附容量低的劣势。采用水热法合成了NaY型沸石吸附剂,对比了其与13X、4A型沸石的CO_(2)吸附特性,研究了压力、温度以及溴化钠改性对CO_(2)吸附能力的影响。结果表明,3种吸附剂的CO_(2)吸附容量均随着温度的上升而下降,随着压力的增加而增加。在25℃、0.1 MPa条件下,NaY型沸石的CO_(2)吸附容量最大,达到3.74 mmol/g。经过8次吸附-脱附循环后NaY型沸石的吸附性能最稳定,只下降了2.5%。采用溴化钠浸渍法对NaY型沸石进行了改性研究,发现溴化钠浸渍改性可以提高NaY型沸石吸附剂的CO_(2)吸附容量。在一定范围内随着溴化钠溶液浓度的增加,改性吸附剂的CO_(2)吸附容量增加。以0.1 mmol/g溴化钠溶液改性的吸附剂在25℃、0.1 MPa条件下具有4.05 mmol/g的CO_(2)吸附容量,相较于未改性的NaY型吸附剂,其吸附容量提升了8.4%。但当溴化钠溶液浓度超过0.1 mmol/g时,进一步提高浓度对于吸附剂性能提升不明显。最佳的溴化钠浸渍改性NaY型沸石的浓度为0.1 mmol/g。

zeolite based CO_(2) adsorbents has many advantages of low energy consumption,low corrosion rate to facility and high cyclic stability,while its adsorption capacity is relatively low.In order to screen out zeolite adsorbents suitable for large-scale CO_(2) capture technology,advanced synthesis methods are needed to improve the CO_(2) sorption capacity of zeolite adsorbents to overcome the disadvantage of low sorption capacity.In this paper,the NaY zeolite was synthesized through hydrothermal synthesis,and the CO_(2) adsorption properties of NaY,13X and 4A zeolite adsorbents were investigated.The influence of pressure,temperature and sodium bromide modification on the adsorption capacity was analyzed comprehensively.The results show that the CO_(2) adsorption capacity of the three adsorbents decreases with the increase of temperature but increases with the increase of pressure.NaY zeolite has the highest CO_(2) adsorption capacity at 25℃,0.1 MPa,which is 3.74 mmol/g.And its adsorption performance maintains stable after 8 regenerative cycles with a decrease of 2.5%.The NaY zeolite modified with sodium bromide impregnation method was investigated.The results show that the CO_(2) adsorption capacity of NaY zeolite enhanced by impregnation modification with sodium bromide.With the increasing concentration of sodium bromide solution,the CO_(2) adsorption capacity of the modified adsorbent increases within certain limits.The NaY zeolite modified with sodium bromide solution of 0.1 mmol/g shows the CO_(2) adsorption capacity of 4.05 mmol/g at 25℃,under 0.1 MPa pressure,of which the performance is improved by 8.4%comparing to the unmodified sorbents.However,when the concentration of the sodium bromide solution exceeds 0.1 mmol/g,the performance of the adsorbent is not significantly improved by further increasing the concentration.The optimal concentration of the sodium bromide solution used for impregnation method is 0.1 mmol/g.