In order to realize the in-situ upgrading process of coal pyrolysis tar, Ni-based catalysts were prepared by in-situ encapsulation method and impregnation method respectively, and the effects of these two catalysts on the in-situ catalytic upgrading of pyrolysis tarwere investigated. Compared with no catalyst, Ni/ HZSM-5 with Ni content of 2% can increase the yield of light components in tar from5.8% to 6.9%, while Ni@ HZSM-5 with the same Ni content can increase the yield of light tar to 7.6%.The influence of Ni/ HZSM-5 andNi@ HZSM-5 catalysts on the yield of each component of tar was further analyzed. The results shows that both catalysts significantly reduces the heavy components in tar, and the asphaltene yield decreases from 5.4 wt.% to 1.3% and 2.0%, respectively. However, compared with Ni/ HZSM-5, Ni@ HZSM-5 increases the yield of light oil and phenol oil by 38.5% and 25.5%, respectively, and naphthalene oil also increases to a certain extent, indicating that the Ni based catalyst prepared by encapsulation method can maximize the retention of light components in tar. This is because in Ni/ HZSM-5, both tar cracking and activation of hydrogen-rich components in pyrolysis gas occur on the Ni surface, which promotes the activation of hydrogen-rich gas and also causes excessive tar cracking. The Ni in Ni@HZSM-5 is mainly distributed in the pore of molecular sieve. Its excellent shape selection catalytic performance enables hydrogen -rich gas molecules to enter into the HZSM-5 and contact with Ni, producing hydrogen-rich free radicals such as ·H and ·CHx, whilelarge molecules in tar cannot enter into the pore of molecular sieve. The cracking can only occur on the acid site on the outer surface ofHZSM-5, avoiding the participation of metal Ni in tar cracking, so as to regulate the amount of tar cracking fragments and hydrogen-richfree radicals, so as to achieve the balance of hydrogen and carbon in the system. As a result, the excessive cracking of tar fragments is effectively avoided and the yield of light tar is improved.

贾鹏(1995—),男,甘肃庆阳人,硕士研究生。E-mail:1820631064@qq.com

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JIA Peng,WANG Mingyi,WANG Yugao,et al.Preparation of encapsulated Ni-based catalyst and its performance in-situupgrading of coal pyrolysis tar[J].Clean Coal Technology,2024,30(4):179-186.