Catalytic cracking of polyethylene over all-silica MCM-41 molecular sieve

Catalytic Upgrading of Plastic Wastes

“…FSM-16 shows textural properties close to those of MCM-41 materials in terms of BET surface area and pore size, the main difference residing in that a layered silicate (kanemite) is used as silica source in its synthesis [46]. Both MCM-41 and FSM-16 have shown activity for the cracking of polyethylene even in their pure silica form [46,47,64]. Recently, another mesoporous silicate (SBA-15) was synthesized with BET surface areas around 600-800 m 2 g −1 and uniform mesopores of dimensions adjustable within the 3.0-30.0 nm range [65].…”

Catalytic Upgrading of Geodae-Uksae 1 over Mesoporous MCM-48 Catalysts

“…In the case of catalytic pyrolysis over Si-MCM-48, only hydrocarbons and pheonlics were affected significantly by catalyst in its fraction in bio-oil. Because Si-MCM-48 has only very weak acid sites due to terminal silanol group and does not have Brønsted and Lewis acid sites, 23 the conversion efficiency on Si-MCM-48 of pyrolytic vapors which were produced from non-catalytic pyrolysis may be not good. In contrast, by Al-MCM-48, the formation of oxygenates was decreased and those of mono-aromatics and furans were increased due to the reaction of deoxygenation, cracking and aromatization on the acid sites of Al-MCM-48.…”

Pyrolysis of Waste Polystyrene and High-Density Polyethylene

“…Although the catalytic degradation of polyethylene over a wide variety of catalysts have been tested, zeolites have proven effective by many researchers [ [Miskolczi et al, 2004;Seddegi et al, 2002;Achilias et al, 2007;Miskolczi et al, 2006;Marcilla et al, 2005;Lin & Yang, 2007;Buekens & Hunang, 1998]. Seo et al (Seo et al,2003) reports that the product characteristics for both thermal and catalytic degradation of waste HDPE using various zeolites are relatively compared as the yields of gas, liquid and residue, and carbon number distribution of liquid products, as shown in Table 1.…”

“…The most commonly used catalysts are (1) solid acid catalysts such as zeolite, silica-alumina, FCC catalyst and MCM-41, etc [Miskolczi et al, 2004;Seddegi et al, 2002;Achilias et al, 2007;Miskolczi et al, 2006;Marcilla et al, 2005;Lin & Yang, 2007] and (2) bifunctional catalysts (Buekens & Huang, 1998). In the degradation of the polymer chain using acidic catalyst, the molecular weight of polymer chain could be rapidly reduced through cracking reaction and then carbonium ion intermediates would be rearranged by hydrogen and carbon atoms shifts with producing the isomers of high quality.…”