کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1197906 964668 2007 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Catalytic activity of zeolitic and mesostructured catalysts in the cracking of pure and waste polyolefins
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آنالیزی یا شیمی تجزیه
پیش نمایش صفحه اول مقاله
Catalytic activity of zeolitic and mesostructured catalysts in the cracking of pure and waste polyolefins
چکیده انگلیسی

Six acid solids of varying acid and textural characteristics has been investigated for their catalytic activity in the degradation of plastic polymers using thermogravimetric and differential thermal analysis. The polymers included pure low-density polyethylene, pure high-density polyethylene and two samples of recycled polyethylene of urban and agricultural origins. The catalysts were three zeolitic materials (standard ZSM-5, nanocrystalline n-ZSM-5 and Beta) and three mesostructured solids (sol–gel Al-MCM-41 (sg), hydrothermal Al-MCM-41 (hy) and Al-SBA-15). The catalytic activity of each acid solid has been related to its capacity to shift the degradation reaction to lower temperatures.Despite showing strong acid properties, standard ZSM-5 zeolite exhibited a very low catalytic activity on most plastics, which was attributed to diffusional impediments that affected the access of the bulky polymer molecules to its internal active sites. These impediments were partly overcome in the case of Beta zeolite and even more markedly with nanocrystalline n-ZSM-5, which exhibited the strongest catalytic activity due to a combination of strong acid properties and large external surface area. Owing to their non-crystalline nature, mesostructured solids showed weaker acid properties than their zeolitic counterparts. However, this disadvantage was partly compensated by the presence of larger pores that reduced diffusional hindrances. Thus, Al-MCM-41 (hy) exhibited one of the highest catalytic activities, largely surpassing the performance of crystalline solids with stronger acid properties. The catalytic activity of all the acid solids tested in this work was significantly reduced when they were used on waste plastics. This deactivating effect was more notable in mesostructured solids.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Analytical and Applied Pyrolysis - Volume 78, Issue 1, January 2007, Pages 153–161
نویسندگان
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