加压热解对煤焦理化结构特性的影响

Influence of pyrolysis pressure on coal char physic-chemical property

为了解煤热解过程中压力对煤焦物化结构的影响规律,采用表面积及孔径分析仪、环境扫描电镜、元素分析仪以及傅里叶红外光谱分析仪与加压热重分析仪相结合的方法研究了不同热解压力(0.1MPa,0.8MPa,1.5MPa,3.0MPa和5.0MPa)下神府煤热解煤焦的物理表面孔隙特性以及煤焦的元素组成、大分子结构以及红外有机官能团的变化特性等微观化学结构.研究发现:随着压力的增大,煤焦的孔隙结构先增后减,压力为0.8MPa时最好,压力对孔隙结构的影响主要表现在孔径为20nm左右的中孔的发展.同时,热解压力对煤焦的化学结构也有明显影响,加压有利于含氧官能团的裂解,加快碳骨架的生长,大分子结构增多,石墨化程度也逐渐加强.这对煤加压气化的了解有着重要的作用.

Influence of pyrolysis on the physic-chemical property of coal char was studied. The surface porosity, elemental composition, macro-molecular structure, and organic functional group of Shenfu coal char observed under variant pressure （0. 1, 0.8, 1.5, 3. 0 MPa, and 5.0 MPa） were analyzed using ASAP2020, SEM, CNHS, and FTIR, coupled with pressurized thermogravimetric analyzer. It was observed that the porosity of char was enriched with pyrolysis pressure increasing （≤0.8 MPa）, and the maximum surface area was obtained at 0.8 MPa, and after that it decreased with pressure in- creased further. The pore volume distribution property shows that the influence of pressure on char pore is mainly displayed on the forming of mesopore （about 20 nm）. Simultaneously, pressure also plays obvious influence on the chemical property of coal char. It is also shown that pressure increment promotes the cracking of O-contained organic functional groups, and the carbon skeleton and more macro-molecular structure form consequently, and the graphitization degree is enhanced gradually, which is important for the catching of coal pressurized gasification.