Production of hydrocarbons from copyrolysis of plastic and tyre material with microwave heating

Abstract

The present invention relates to the development of a microwave pyrolysis process for plastic materials selected from PE, PP, PS, PET, PVC and mixtures thereof in the presence of end-of-life tyres, or the pyrolysis residues thereof, or other carbon materials for the production of high added value pyrolysis oils containing over 50% by weight hydrocarbons distillable between 20 and 250° C. and a sulphur content less than 1% by weight.

1 . A process comprising subjecting plastic materials such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), polyvinyl chloride (PVC) and mixtures thereof, to pyrolysis by way of irradiation with microwaves (MW) said plastic materials being mixed with end-of-life tyres (PFU), or the solid pyrolysis residues thereof or other carbon materials, said process characterised in that:
 (a) the vapours derived from the pyrolysis reaction are conveyed in a fractionation system before being sent to a condensation system; or   (b) the delivery of the MW is at such a power level as to obtain a mean percentage pyrolysis rate (V M % ) of less than, or equal to, 1.0/min and/or a mean heating rate ( VM risc ) of less than, or equal to, 10° C./min, in case of pyrolysis induced by PFU; or delivery of the MW at such a power level as to obtain a mean pyrolysis rate (V M % ) of less than or equal to 2.0/min and/or a mean heating rate (V M risc ) of less than or equal to 15° C./min, in the case of pyrolysis induced by PFU pyrolysis residues and the vapours derived from the pyrolysis reaction are directly sent to a condensation system, without being conveyed in a fractionation system before being sent to the condensation system;   for obtaining pyrolysis oils having a content greater than 50% by weight of hydrocarbons distillable between 20 and 250° C. and having a sulphur content less than 1% by weight.   
     
     
         2 . The process according to  claim 1 , subparagraph (a) wherein the fractionation system is selected from:
 Dephlegmator with air-cooling   Dephlegmator with column filled with Fenske, Rashig, Pall, Lessing, and Cross-Partition rings   Dephlegmator with column filled with Berl, or Intalox saddles   Dephlegmator with column filled with glass beads of various diameters (0.5 to 4 mm)   Dephlegmator with plate column   a similar industrially viable system.   
     
     
         3 . The process according to  claim 2  wherein the delivery of the MW is at such a power level as to obtain a V M %  greater than 0.5/min and/or an mean heating rate (V M risc ) greater than 3.5° C./min. 
     
     
         4 . The process according to  claim 1  wherein the plastic material/PFU weight ratio varies between 0.25 and 8.0, while in the case of the use of plastic materials/solid PFU pyrolysis residue, said ratio varies between 1.0 and 2.0. 
     
     
         5 . The process according to  claim 1 , subparagraph (b) wherein  VM %  is greater than 0.2 min −1  and/or V M risc  is greater than 2.0° C./min, when PFU is are used in the mixture with plastic materials; or in the case of pyrolysis of plastic materials induced by the presence of PFU pyrolysis residues, then V M %  is greater than 0.7/min, which corresponds to a V M risc  greater than 8.0° C./min. 
     
     
         6 . The process according to  claim 1  wherein to lower the sulphur content in pyrolysis oil, a sulphurated compounds sequestering agent is used during the process. 
     
     
         7 . The process according to  claim 1  wherein for pdelivery of the MW, one or more generators, operating at a frequency of 2.45 GHz, are used.