A process and two-step catalytic reactor system for the production of liquid hydrocarbons from plastic waste

Abstract

The present invention relates to a process and a system for the production of liquid hydrocarbons by thermo-catalytic cracking of plastic waste. The invention relates to a technique for efficiently producing high-quality liquid fuel using designed reactor setup for the cracking of waste plastic. The invention also relates to a thermo-catalytic cracking method, which occurs in the presence of zeolite-based catalysts, more preferably the zeolite catalysts impregnated with transition metals which remain catalytically active up to 8-10 sets of reactions with higher selectivity of petroleum range hydrocarbons. The present invention also relates to a two-step approach system for the production of liquid hydrocarbons.

1 . process for the production of liquid hydrocarbon from plastic waste comprising the steps of:
 (i) thermally cracking plastic waste in a thermal cracking zone at a temperature of about 200 to 400° C. forming hydrocarbon vapors;   (ii) catalytically cracking said hydrocarbon vapors in a catalytic cracking zone with a zeolite catalyst impregnated with a transition metal selected from the group consisting of Fe, Cu, Co, or Ni at a temperature of about 300 to 400° C.; and   (iii) condensing the hydrocarbon vapors at a temperature of about −5 to about 15° C. forming fuel-like hydrocarbon having C 5  to C 28  hydrocarbon fractions; wherein 60-80% of fuel-like hydrocarbon formed are liquids and 20-35% are gases.   
     
     
         2 . The process as claimed in  claim 1 , wherein the zeolite catalyst is impregnated with copper or iron. 
     
     
         3 . The process as claimed in  claim 1 , wherein the ratio of the catalyst to plastic waste is in the range of 1:10 to 1:30. 
     
     
         4 . The process as claimed in  claim 1 , wherein fuel-like hydrocarbons have C5 to C18 hydrocarbon fractions. 
     
     
         5 . The process as claimed in  claim 1 , wherein the fuel-like hydrocarbon has calorific value in the range of 42 to 45 MJ/kg. 
     
     
         6 . The process as claimed in  claim 1 , wherein the catalyst retains reactivity for about 8-10 sets of reactions. 
     
     
         7 . The process as claimed in  claim 1 , wherein the thermal cracking and catalytic cracking reaction is completed in 10 to 25 minutes. 
     
     
         8 . The process as claimed in  1 , further comprises the steps of separating, sizing, pelletizing and/or processing the plastic waste prior to thermal cracking. 
     
     
         9 . A two-stage hatch reactor system for producing a fuel-like hydrocarbons from plastic waste comprising:
 (i) a thermal cracking zone adapted to receive plastic waste;   (ii) a catalytic cracking zone arranged vertically and connected to said thermal cracking zone and comprising zeolite catalytic bed; wherein the zeolite catalyst is impregnated with a transition metal selected from the group consisting of Fe, Cu, Co, or Ni; and   (iii) a condenser connected to said catalytic cracking zone maintained at about −5 to about 15° C. temperature range.   
     
     
         10 . The system as claimed in  claim 9 , wherein the catalytic cracking zone is arranged vertically about 20-30 mm above the thermal cracking zone, having L/D ratio in the range of 70-40 mm such that there is an immediate interaction of vapor from the thermal cracking zone and the catalyst bed. 
     
     
         11 . The system as claimed in  claim 9 , further comprises an inert gas cylinder supplying inert gas to the thermal cracking zone. 
     
     
         12 . The system as claimed in  claim 9 , further comprises a hydrocarbon gas collector and a hydrocarbon liquid collector connected to said condenser.