吸附剂表面性质对柴油碱性氮化物吸附脱除的影响

对硅胶、改性硅胶、活性白土和γ-Al2O3四种吸附剂进行柴油吸附脱除碱性氮化物试验以及BET分析和吡啶吸附红外分析。结果表明，室温下硅胶在拐点前的碱性氮化物吸附等温式为： ；改性硅胶吸附碱性氮化物的吸附等温式为： ；γ-Al2O3的碱性氮化物吸附等温式为： ；活性白土的碱性氮化物吸附等温式为： 。研究发现，吸附剂比表面积不是吸附脱除柴油碱性氮化物的主要影响因素，孔径小于3.5nm时会阻碍碱性氮化物在吸附剂表面的扩散，降低吸附剂吸附容量。碱性氮化物在吸附剂表面的吸附作用以化学吸附为主, 随着吸附剂表面酸中心增加，吸附剂对碱性氮化物的吸附容量增加。

EFFECTS OF THE SURFACE PROPERTIES OF ADSORBENTS ON THE REMOVAL OF BASIC NITROGEN COMPOUNDS FROM DIESEL FUEL

The adsorption removal of basic nitrogen compounds from diesel fuel was studied and four adsorbents including silica gel,acid modified silica gel,activated clay and γ-Al_2O_3 were involved.The surface properties of the adsorbents were investigated by nitrogen adsorption-desorption(BET)and pyridine-IR analysis.Results indicate that at room temperature the adsorption isotherm before B point can be expressed by Freundlich equation,the equation for silica gel,acid modified silica gel,activated clay and γ-Al_2O_3 is α=0.15w~(0.44),α=0.10w~(0.27),α=0.61w~(0.35) and α=0.21w~(0.40),respectively.It seems that the specific surface area of the adsorbent is not the major factor affecting the removal of basic nitrogen compounds from diesel fuel,yet pore with diameter less than 3.5 nm could obstruct the diffusion of basic nitrogen compounds,resulting in the decrease of adsorption capacity.Since most of the basic nitrogen compounds are chemically adsorbed on the adsorbent,with the increase of acid sites on the adsorbent surface the adsorption capacity increases.