Coprocessing coal with plastics

M. Luo and C. W. Curtis, Two stage coprocessing of coal with model and commingled waste plastics mixtures. Fuel Process. Technol, 59, 163 (1999). 

The research on the liquefaction of waste polymers and the coprocessing of waste plastics with vacuum residue or coal has been a subject of study by many groups at universities and environmental agencies. A significant amount of effort and funds are being diverted to develop process technology in order to convert mixed plastics waste from municipal... 

In addition to the above-mentioned catalytic processes, there are some other related technologies wherein the catalytic cracking of plastic wastes is combined with the coprocessing of other substances, mainly coal and petroleum feedstocks (lube oil, LCO, VGO) or even a solvent. Hereafter, these technologies are explained more in detail. 

Figure 3.18 Scheme of a two-stage process for waste plastics and coal coprocessing [106]. (Reproduced with permission from Elsevier)... 

M. Lno and C. W. Cnrtis, Effect of reaction parameters and catalyst type on waste plastics liqnefaction and coprocessing with coal. Fuel Process. Technol. 49, 177 (1996). 

H. K. Joo, and C. W. Curtis, Catalytic coprocessing of plastics with coal and petroleum resid using NiMo/Al203. Energy Fuels., 10(3), 603 (1996). 

Thermal processes are mainly used for the feedstock recycling of addition polymers whereas, as stated in Chapter 2, condensation polymers are preferably depolymerized by reaction with certain chemical agents. The present chapter will deal with the thermal decomposition of polyethylene, polypropylene, polystyrene and polyvinyl chloride, which are the main components of the plastic waste stream (see Chapter 1). Nevertheless, the thermal degradation of some condensation polymers will also be mentioned, because they can appear mixed with polyolefins and other addition polymers in the plastic waste stream. Both the thermal decomposition of individual plastics and of plastic mixtures will be discussed. Likewise, the thermal coprocessing of plastic wastes with other materials (e.g. coal and biomass) will be considered in this chapter. Finally, the thermal degradation of rubber wastes will also be reviewed because in recent years much research effort has been devoted to the recovery of valuable products by the pyrolysis of used tyres. 

Thermal Coprocessing of Plastic Wastes with Coal and Lignocellulosic Materials... 

In recent years, a lot of research effort has been focused on the coprocessing of coal and rubber or plastic wastes under hydrogen atmospheres, based on the possible role of the polymers as hydrogen donor for coal. Therefore, in this chapter the description of plastic and rubber hydrogenation processes is followed by sections dealing with their coprocessing with coal. 

In recent years, new interesting alternatives have been proposed for the thermal conversion of plastic wastes, such as their coprocessing with coal or degradation in the presence of solvents, although more intensive study of these methods is needed. 

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