生物质焦的表征及其吸附烟气中汞的研究

选用四种生物质即稻杆(RS)、稻壳(RH)、松木屑(WC)和棉花杆(CS)制备了生物质焦,利用N₂吸附/脱附和傅里叶变换红外光谱(FT-IR)仪,对制备的生物质焦的孔隙结构和表面化学性质进行了表征,分析生物质种类和制焦条件对生物质焦性质的影响。在固定床汞吸附实验台上研究了生物质焦的脱汞性能。结果表明,随着热解温度的升高,生物质焦的比表面积、微孔容积、分形维数等参数有先增大后减小的趋势。WC600、RS600、RH600均有较好的孔结构特性;热解温度升高,生物质焦表面官能团的数量和种类随之减少。不同生物质制备的焦样表面官能团的数量和种类差异较大。其中,RH600和RS600的表面官能团的种类比较丰富,而且含量相对较多。但WC600和CS600表面的官能团种类和数量都很少。生物质焦的单位汞吸附容量与其分形维数以及微孔容积之间并非简单的依附关系,其吸附能力还受含氧官能团等其他因素的影响。

Characterization of biomass char and its mercury adsorption performance

Four biomass of rice straw(RS),rice husk(RH),wood chips(WC) and cotton straw(CS) were chosen to prepare biomass chars which characterized by nitrogen adsorption/desorption and Fourier transform infrared spectroscopy(FT-IR).The influence of biomass type and pyrolysis temperature on pore structure and surface chemical properties of the chars was investigated.Mercury adsorption experiments were carried out in a fixed-bed reactor.The results show that specific surface area,micro-pore volume and fractal dimension of the biomass chars increase firstly and then decrease with increase of the pyrolysis temperature.With the pyrolysis temperature increasing,both the quantity and sorts of the superficial functional groups on the biomass chars reduce and they are dependent greatly on the biomass sorts.Both the superficial functional groups and contents of RH600 and RS600 are more abundant than that of WC600 and CS600.It is not simply direct relationship among the mercury adsorption capacity,the micro-pore volume and the fractal dimension of the biomass chars.It is supposed that the oxygen contained functional group may have dominant effect on the mercury adsorption.