摘要
为了考察小晶粒分子筛团聚对亚微米级5A分子筛粒度分布结果的影响以及适宜的测定条件,实验以水为分散介质,六偏磷酸钠为分散剂,在超声波辅助作用下,用电位/粒度分析仪测定研究了试样浓度、分散剂用量和超声时间对亚微米级5A分子筛分散性的影响。结果表明,当分子筛含量大于5 g/L时,晶粒团聚现象严重,粒度分布呈现单峰（假象）,导致粒度测量结果偏大;加入少量（0.005~0.195 g/L）的六偏磷酸钠,有缓解晶粒团聚作用,可将较大团聚粒子（大于2.8μm）分散为较小粒子（1.3μm左右）,少量团聚粒子分散成单个晶粒,可测得较小晶粒粒径;超声作用可使较大团聚粒子（0.85~2.80μm）分布峰强度降低,相对较小粒子（0.30~0.85μm）分布峰强度增加。超声时间不宜太长,否则将加剧粒子间团聚,使得测定粒径偏大。当试样中5A分子筛含量为5 g/L,六偏磷酸钠浓度0.195 g/L、超声时间4 min条件下,测得5A分子筛试样粒径分布0.25~0.80μm,峰顶对应粒径为0.473μm,中位径（d50）为0.784μm,与电镜分析结果一致,说明是较为准确的粒度分析方法。
This paper discusses the effect of small grain agglomeration on the particle size distribution （PSD） of 5A submicron zeolite and the appropriate measuring methods. Water and sodium hexametaphosphate were chosen as a disperse medium and a dispersant, respectively. The influences of zeolite concentration, dispersant dosage and time of ultrasonic treatment on the dispersion state were studied by a potential/particle size analyzer with ultrasonic treatment. Results show that when zeolite concentration is more than 5 g/L, the PSD appears to be a unimodal distribution （false appearance）, leading to a large measured size due to severe agglomeration. A small amount of sodium hexametaphosphate （0.005-0.195 g/L） additive can alleviate the agglomeration by dispersing most large agglomerated particles （more than 2.8 μm） into relatively small agglomerates （about 1.3 μm） and some agglomerates into single crystals so that the small particles can be measured. Ultrasonic treatment reduces the PSD intensity of large agglomerates （0.85-2.80 μm） and increase the PSD intensity of small agglomerates （0.30-0.85 μm）. However the time of ultrasonic treatment should not be too long, otherwise the agglomeration becomes severe. When the sample content is 5g/L and dispersant concentration is 0.195 g/L, after 4 min ultrasonic treatment, the PSD is determined to be 0.25-0.80μm, of which the peak value is 0.473 μm and the median diameter d50 is 0.784 μm, that is consistent with SEM results.
出处
《化学反应工程与工艺》
CAS
CSCD
北大核心
2013年第1期59-64,共6页
Chemical Reaction Engineering and Technology
关键词
亚微米5A分子筛
粒度分析
粒径
六偏磷酸钠
超声
团聚
sub-micro 5A zeolite
particle size analysis
particle size
sodium hexametaphosphate
ultrasonic
agglomeration
