With lignite after vacuum drying as the raw material,a series of Zn-based sorbents were prepared by static impregnation,ultrasonic-assisted impregnation,bubbling-assisted impregnation and high-pressure impregnation.The physical properties and the desulfurization performances of Zn-based sorbents were studied systematically by XRD,BET,AAS characterization techniques and the fixed-bed desulfurization evaluation apparatus.The sorbents obtained by high-pressure impregnation method have a larger specific surface area,pore volume and pore diameter comparing with other methods,which is conducive to the sulfidation reaction of hydrogen sulfide gas in the sorbent.The effects of pressure during the high-pressure impregnation and concentration of Zn(NO3)2 precursor solution on the sorbents properties and desulfurization behavior were investigated.The higher the impregnation pressure and the concentration of impregnation solution are,the greater the amount of the active components are uploaded.However,overhigh impregnation pressure can cause collapse and blocking of the carrier pore.The optimal operating condition of high-pressure impregnation method for preparing the sorbents was the impregnation pressure of 20 atm and the solution concentration of 41%.Under that condition,the sorbent had the best desulfurization ability with a sulfur capacity of 13.94 gS/100 gsorbent and a breakthrough time of 54 h.Its desulfurization precision and efficiency of removing H2S before sorbent breakthrough from the middle temperature gases of 400℃ can reach<5 ppm and>99%,respectively.Sorbents could be regenerated under the condition of 1 vol%O2,20 vol% H2O,0.5 vol% NH3,and N2balance gas.The regenerated sorbent could be used for repeated absorption of H2S with a slight decrease in desulfurization effect.
Yurong DongXiurong RenMeijun WangQiang HeLiping ChangWeiren Bao
采用等体积浸渍法制备了Ni/Al2O3及La改性的Ni-La/Al2O3催化剂,并考察了其浆态床CO甲烷化反应性能。借助XRD、H2-TPR、CO-TPD、H2-TPD等对催化剂进行了表征。结果表明,La助剂改性制备的Ni-La/Al2O3催化剂较Ni/Al2O3催化剂具有更高的CO甲烷化活性,La助剂的添加促进了Ni物种在载体表面的分散,降低了还原温度,增强了催化剂对CO和H2的吸附能力。La助剂的添加次序对甲烷化活性影响较大,采用共浸渍法制备的催化剂具有最佳的甲烷化活性,CO转化率达到96.3%,CH4选择性和时空收率分别达到87.1%和179.6 m L·kg-1·h-1,优于先浸渍Ni后浸渍La或先浸渍La后浸渍Ni制备的催化剂。
High-pressure impregnation, a new preparation method for sorbents to remove H2S from hot coal gas, is introduced in this paper. Semi-coke (SC) and ZnO is selected as the support and active component of sorbent, respectively. The sorbent preparation process includes high-pressure impregnation, filtration, ovendry and calcination. The aim of this research is to primarily study the effects of the impregnation pressure on physical properties and desulfurization ability of the sorbent. The desulfurization experiment was carried out in a fixed-bed reactor at 500°C and a simulated coal gas used in this work was composed of CO (33 vol%), H2 (39 vol%), H2S (300 ppm in volume), and N2 (balance). Experimental results show that the pore structure of the SC support can be improved effectively and ZnO active component can be uniformly dispersed on the support, with the small particle size of 10-500 nm. Sorbents prepared using high-pressure impregnation have better desulfurization capacity and their active components have higher utilization rate. P20-ZnSC sorbent, obtained by high-pressure impregnation at 20 atm, has the best desulfurization ability with a sulfur capacity of 7.54 g S/100g sorbent and a breakthrough time of 44 h. Its desulfurization precision and efficiency of removing H2S from the middle temperature gases can reach <1 ppm and >99.7%, respectively, before sorbent breakthrough.
