利用稻壳气化残渣制备K-ZSM-5分子筛的研究  

K-ZSM-5 Zeolite Production Using Rice Husk Ash from Biomass Gasfiers

作　　者：郎林[1] 王凤旵[1] 张超[1] 阴秀丽[1] 吴创之[1] 

机构地区：[1]中国科学院广州能源研究所,广州510640

出　　处：《农业机械学报》2013年第9期107-113,共7页Transactions of the Chinese Society for Agricultural Machinery

基　　金：'十二五'国家科技支撑计划资助项目(2011BAD22B06);广东省自然科学基金重点项目(10251007006000000)

摘　　要：以生物质稻壳气化残渣(RHA)为原料,通过KOH溶液高温水热反应制取RHA硅溶胶,采用水热合成法制备K-ZSM-5分子筛。考察了热水反应时间对Si溶出率的影响,分析了RHA硅溶胶的复杂物质组成。研究了RHA硅溶胶复杂合成体系中,模板剂种类、硅铝摩尔比、晶化温度和晶化时间等因素对K-ZSM-5分子筛成核与生长过程的影响规律;并采用XRD、SEM、ICP、TG、N2吸附脱附等手段表征分子筛晶体。结果表明:直接以RHA硅溶胶为原料合成K-ZSM-5分子筛时,对有机模板剂的结构导向作用要求较高;采用乙醇类的弱有机模板剂无法合成出分子筛晶体;采用低含量的TPABr强有机模板剂,可以在一定硅铝摩尔比范围内合成出晶形较为完备的K-ZSM-5分子筛晶体,但存在合成体系可调范围比较窄,晶形杂乱且粒度较大,合成温度较高,合成时间较长等劣势。实验还发现,煅烧方式对所合成的大粒度K-ZSM-5分子筛晶体的孔道结构影响较大,直接550℃高温煅烧容易形成积碳,须在350℃中温热解3 h后,再550℃高温煅烧才能获得纯净的K-ZSM-5分子筛产品。The rice husk ash（RHA） from biomass gasifiers was hydrothermally reacted with KOH solution to obtain the RHA ludox,which was used to synthesize K-ZSM-5 zeolite by hydrothermal crystallization.The effect of hydrothermal reaction time on the Si dissolving rate was investigated,and the complex composition of the RHA ludox was analyzed as well.The effects of template types,Si/Al molar ratio,crystallization temperature and time on the nucleation and growth of K-ZSM-5 zeolite in the complex RHA synthesis system were studied.The as-synthesized samples were characterized by XRD,SEM,ICP,TG,N 2 adsorption-desorption and other means.The results showed that the structural directing agents with strong template effect were necessary to synthesize K-ZSM-5 zeolite directly using the RHA ludox.The zeolite crystals could not be prepared by the weak organic template as ethanol,however,using little TPABr strong template,the K-ZSM-5 zeolite crystals could be synthesized with a certain range of the Si/Al molar ratio.But there were some disadvantages such as the narrow adjustable range of synthesis solution,irregular crystal shape,large grain size,high synthesis temperature,long reaction time,and so on.It was also found that the calcination methods had great influence on the pore structure of large KZSM-5 products.It was easy to form deposited carbon over the zeolite crystals that were directly calcined at 550℃.To obtain pure K-ZSM-5 products,it must be calcined at 350℃ for 3 h before hightemperature calcination at 550℃.

关 键 词：稻壳灰 分子筛 水热合成 

分 类 号：TK6[动力工程及工程热物理—生物能]