K_(2)CO_(3)催化煤炭不完全气化联产高强度颗粒炭及富氢合成气研究

Co⁃production of high strength extruded activated carbon and hydrogen⁃rich syngas via K_(2)CO_(3)catalytic incomplete gasification of coal

煤气化技术是煤炭清洁高效利用的重要技术。然而,煤气化过程气化碳转化率无法达到100%并产生大量废渣,而细渣中高含量且孔隙发达的残炭提取困难,使得大量堆积的细渣很难资源化利用。从细渣产生的源头出发,采用低灰煤圆柱状成型煤颗粒在K_(2)CO_(3)催化下进行不完全气化(在碳转化率达到70%~80%时终止气化)联产高性能活性炭及富氢合成气,并研究气化气体产物组分和所制备K掺杂活性炭AC-Kx的CO_(2)吸附性能及K对CO_(2)吸附性能的影响。结果表明:在纯水蒸气气氛下,外部热源供热气化终温950℃条件下,Kx催化不完全气化气体产物中H_(2)/CO体积分数比值在2.20~6.29,氢碳比f在1.37~2.32。与未掺杂钾的样品相比,K_(2)CO_(3)催化气体产物的氢碳比显著提高;气化后期产生的气体中CO和CO_(2)体积分数偏高,说明不完全气化及时终止气化反应可提升合成气的氢碳比,同时降低煤气化工艺的碳排放;当K_(2)CO_(3)掺配量为原料煤的5%时,所制备活性炭AC-K5的BET比表面积达到1051 m^(2)/g,亚甲基蓝吸附值达到215 mg/g,耐磨强度95.8%。在200℃中温条件下,AC-K5的CO_(2)吸附量较未掺杂活性炭提升1.63倍。通过K催化煤颗粒不完全气化在生产富氢合成气的同时可联产用于CO_(2)捕集的高强度颗粒炭,提升了煤催化气化的经济性。

Coal gasification technology is an important technology for clean and efficient utilization of coal.However,the carbon conversion of coal gasification process cannot reach 100%and thus a large amount of waste slag containing carbon residue is produced.The high content of porous carbon residue in the fine slag is difficult to ex⁃tract,which results in the difficult utilization of large accumulation of fine slag.In this paper,starting from the source of fine slag formation,the low ash cylindrical coal particles were incompletely gasified over K_(2)CO_(3)catalyst(the gasification was terminated when the carbon conversion rate reached about 70%-80%)to produce hydrogen⁃rich syngas and K⁃doped activated carbon(AC-Kx)with high⁃performance.The components of gasification gas and the CO_(2)adsorption performance of AC-Kx as well as the role of residual K in AC-Kx were also investigated.The results show that at the gasification final temperature of 950℃,the H_(2)/CO ratio and the hydrogen⁃carbon ratio f could reach 2.20-6.29 and 1.37-2.32,respectively,in the gas product from K_(2)CO_(3)catalytic incomplete steam gasification.Compared with the sample without potassium doping,the f of gas products from the K-doped samples increased significantly.The volume fraction of CO and CO_(2)in the gas produced in the later stage of gasification was high,indicating that the incom⁃plete gasification and timely termination of gasification reaction could increase the hydrogen⁃carbon ratio of syngas and reduce the carbon emission of coal gasification process.When the addition amount of K_(2)CO_(3)was up to the 5%of coal mass,the BET specific surface area,methylene blue adsorption value and the abrasive resistance of resultant AC-K5 reached 1051 m^(2)/g,215 mg/g and 95.8%,respectively.At 200℃,the CO_(2)adsorption capacity of AC-K5 was 1.63 times higher than that of AC-K0.It can be concluded that the incomplete gasification of coal particles cata⁃lyzed by K_(2)CO_(3)can simultaneously produce hydrogen⁃rich syngas and the activated carbon with high abrasive resist⁃ance for CO_(2)capture,improving the economy of coal catalytic gasification.