Effect of Catalyst Acidity and Structure on Polymer Cracking

摘要CTS-9509240这项工作研究了利用催化裂化将塑料废物转化为有用的碳氢化合物混合物。比较了无定形硅铝和不同晶态沸石的聚合物裂解性能，确定了沸石孔道尺寸对产物分布的影响；比较了铝硅酸盐和硫酸氧化锆酸催化剂的裂解性能，确定了催化剂酸度的影响；还研究了含铂催化剂在氧气或氢气气氛中裂解时产物分布的变化。挥发性裂解产物通过微炉进样器的气相色谱和质谱仪和红外光谱的检测来鉴定。利用固定床催化反应器研究了催化剂结焦过程以及裂化气氛和温度对产物分布的影响。聚合物裂解的总活化能由热重(TGA)方法获得，产物比活化能由热重-质谱仪(TGA-MS)线性程序热降解质谱仪获得。所研究的聚合物包括聚乙烯、聚丙烯、聚苯乙烯和聚氯乙烯。今天使用的大多数塑料都是由不可生物降解的聚合物制成的，这使得它们在固体废物垃圾填埋场中不受欢迎。尽管有些社区存在“回收”计划，但事实上，没有经济上可以接受的技术来以有意义的方式回收大多数聚合物。该项目为这种技术奠定了基础。***

ABSTRACT CTS-9509240 This effort examines the use of catalytic cracking to convert plastic wastes into useful hydrocarbon mixtures. Polymer-cracking properties of amorphous silica-alumina and of various crystalline zeolites are compared to ascertain the effects of zeolite channel dimensions on product distributions; cracking properties of aluminosilicates are compared with those of a sulfated zirconia superacid catalyst to ascertain the effects of catalyst acidity; product distribution changes from cracking in oxygen or hydrogen atmospheres with catalysts containing platinum are also studied. Volatile cracking products are identified from gas chromotagraphy with a microfurnace injector and detection by both mass spectrometry and infrared spectroscopy. A fixed-bed catalytic reactor is used to study catalyst coking processes and the effects of cracking atmosphere and temperature on product distributions. Overall activation energies for polymer cracking are obtained from thermogravimetric (TGA) methods; product-specific activation energies are obtained from TGA-MS using linear programmed thermal degradation mass spectrometry. Polymers studied include polyethylene, polypropylene, polystyrene, and polyvinyl chloride. Most plastics in use today are made of nonbiodegradable polymers; this makes them undesirable in solid-waste landfills. Although "recycling" programs exist in some communities, there is, in fact, no economically acceptable technology to recycle most polymers in a meaningful way. This project lays the fundamental groundwork for such a technology. ***