生物质/塑料共催化热解过程中HZSM-5失活分析  

Deactivation of HZSM-5 during the catalytic co-pyrolysis of biomass and plastic

作　　者：张东红 任夏瑾 蔡红珍[1] 易维明[1] 柳善建[1] 林晓娜 ZHANG Donghong;REN Xiajin;CAI Hongzhen;YI Weiming;LIU Shanjian;LIN Xiaona(School of Agricultural Engineering and Food Science,Shandong University of Technology,Zibo 255000,Shandong,China)

机构地区：[1]山东理工大学农业工程与食品科学学院,山东淄博255000

出　　处：《化工进展》2021年第8期4259-4267,共9页Chemical Industry and Engineering Progress

基　　金：国家自然科学基金(51806129);山东省自然科学基金(ZR2017BEE062)。

摘　　要：利用管式炉热解装置进行HZSM-5在线共催化热解玉米秸秆/高密度聚乙烯过程中的循环和再生利用实验,对玉米秸秆进行酸洗预处理,考察原料酸洗预处理对HZSM-5催化性能的影响。采用GC-MS(气相色谱-质谱联用仪)对生物油的化学组成进行分析,并对反应前、反应后以及再生催化剂进行TG(热重分析)、ICP-MS(电感耦合等离子体发射光谱仪)、SEM/EDS(场发射扫描电镜)、BET、NH3-TPD(程序升温脱附技术)等表征分析。研究表明,HZSM-5催化玉米秸秆/高密度聚乙烯热解的主要产物为芳烃,随着催化剂重复利用次数的增加,芳烃含量逐渐降低,催化剂的比表面积、孔容、酸性等也随之降低,说明催化剂的活性逐渐降低;原料经酸洗预处理后有利于热解中间体的生成,加速了催化剂的结焦失活速率;催化热解酸洗玉米秸秆/高密度聚乙烯的催化剂经焙烧再生后其活性基本恢复至原有水平,而催化热解未处理玉米秸秆/高密度聚乙烯的催化剂再生后其活性有所降低,碱/碱土金属在HZSM-5催化剂上发生累积,从而引起酸性位点“中毒”失活,而原料经酸洗预处理后可有效降低催化剂上碱/碱土金属的累积量,有利于延长催化剂的使用寿命。The reuse and regeneration of HZSM-5 zeolite in the catalytic co-pyrolysis of corn stover/high-density polyethylene was investigated using a tube reactor.The effect of acid washing treatment of corn stover on the catalytic activities of HZSM-5 zeolite was studied.The composition of the obtained biooil was analyzed by GC-MS,and the properties of fresh,spent,and regenerated HZSM-5 catalysts were measured using TG,ICP-MS,SEM/EDS,BET,and NH3-TPD,respectively.The results showed that aromatics were the main products for the catalytic co-pyrolysis of corn stover/high-density polyethylene with fresh HZSM-5.With the increase of HZSM-5 reuse times,the yield of aromatics decreased gradually,and the BET area,pore volume,and acidity of the catalyst decreased sharply,indicating the reduced catalytic activities of HZSM-5.The acid washing pretreatment of corn stover enhanced the formation of oxygen-containing intermediates,which accelerated the deactivation of HZSM-5 zeolite.The catalytic activity of the regenerated HZSM-5 over acid washing corn stover/high-density polyethylene was recovered,while the catalytic activity of the regenerated HZSM-5 over raw corn stover/high-density polyethylene was slightly lower than that of fresh HZSM-5.This was due to the fact that alkali/alkaline earth metals were significantly accumulated over the HZSM-5 catalyst,which couldn’t be removed by calcination and thus could deposit on the strong acid sites,causing the“poisoning”deactivation of the catalyst.The above results suggest that the deactivation of HZSM-5 caused by coke can be regenerated by calcination,while that caused by alkali/alkaline earth metals is difficult to recover.The acid-washing pretreatment can effectively eliminate the effect of alkali/alkaline earth metals,which is beneficial to prolong the lifetime of the catalyst.

关 键 词：生物质 塑料 热解 HZSM-5 失活 碱/碱土金属 

分 类 号：TK6[动力工程及工程热物理—生物能]