Gasoline from waste plastics

The production of gasoline, kerosene and diesel from waste plastics is an emerging technological solution to the vast amount of plastics that cannot be economically recovered by conventional mechanical recycling. 

An alternative process based on two sequential catalytic cracking stages aimed at obtaining gasoline and diesel from waste plastics or heavy oil/waste plastics mixtures is shown in Figure 3.16 [99]. The catalyst employed in the first step is made up of powder alumina, waterglass and HZSM-5 zeolite and is mixed up directly with the waste plastics in a screw reactor preferably at 600-700°C. The second catalytic step consists in a fixed... 

H. J. Kwak, Method and system for continuously preparing gasoline, kerosene and diesel oil from waste plastics, US Patent 6866830, 2005. 

A. R. Songip, T. Masuda, H. Kuwahara, and K. Hashimoto, Production of high quality gasoline by catalytic cracking over rare-earth metal exchanged y-type zeolites of heavy oil from waste plastics. Energy and Fuels, 8, 136 (1994). 

Table 6.6 Comparison of commercial gasoline and the gasoline obtained from heavy oil derived from waste plastics. (Reproduced by permission of the American Chemical Society)...

Korean Patent 0191075 Method and System for Continuously Preparing Gasoline, Kerosene and Diesel Oil From Waste Plastics Patent issued January 1999. 

Mei Li and Aiping Hou, Apphcation of mannfactnring gasoline and diesel oil from waste plastics. Plastics Science and Technology, (6), 25 (1994). 

Resources, Conservation Recycling 23,No.3, 1998,p.l63-81 CATALYTIC PLASTICS CRACKING FOR RECOVERY OF GASOLINE-RANGE HYDROCARBONS FROM MUNICIPAL PLASTIC WASTES Buekens A G Huang H Brussels,Free University... 

Some reactions occur very rapidly others very, very slowly. For example, in the production of polyethylene, one of our most important plastics, or in the production of gasoline from crude petroleum, we want the reaction step to be complete in less than one second, while in waste water treatment, reaction may take days and days to do the job. 

A. G. Buekens and H. Huang, Catalytic plastics cracking for recovery of gasoline-range hydrocarbons from municipal plastic wastes. Resources, Conservation and Recycling, 23, 163 (1998). 

Although direct liquefaction of waste plastic looked promising, problems associated with impurities (paper, aluminum, etc.) and chlorine derived from PVC caused operational difficulties. Consequently, it currently appears that the first step of any feedstock recycling process for waste plastics or tires should be pyrolysis, which allows much easier separation of solid impurities and chlorine. Research on pyrolysis of post-consumer plastic has been carried out by Kaminsky and co-workers [17, 18], Conrad Industries [19, 20], and Shah et al. [21]. Shah et al. [21] conducted pyrolysis experiments on relatively dirty post-consumer waste plastic obtained from the DSD. The pyrolysis oils were then subjected to hydroprocessing to convert them into high-quality transportation fuels (gasoline, kerosene, diesel). 

The catalytic cracking of polypropylene waste in a flnidized-bed reactor was reported by Ji [12]. It gave a yield of liquid product of 50%, the research octane number of the gasoline prodnced from plastic waste was 86, and the cetane index of the diesel fuel produced from the plastic waste was 43. 

Obsolete automobiles are typically shredded for the recovery of ferrous scrap. The nonmetallic fraction of shredded automobiles is auto shredder residue (ASR), a heterogeneous mixture of plastics, glass, rubber, fibers, foam, upholstery, dirt and fines. ASR may typically be contaminated with any of the original constituents of an automobile such as brake fluid, steering fluid, motor oil, gasoline or heavy metals. It is estimated that 250-275 lb. of plastic are used in a 3,500 lb. auto and that up to 1.2 million tons of waste plastic from ASR are generated per year [Bonsignore ct al., 1991]. A breakdown of automotive plastic scrap for the 1981 model year has shown that the thermoplastics ABS, PUR, PP and PVC comprise 65% of waste plastic. 

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