Method for recovering light olefin monomer through oriented pyrolysis of waste plastics

The invention discloses a method for recovering light olefin monomers by directional pyrolysis of waste plastics, which comprises the following steps: putting a molecular sieve catalyst into a second section reaction zone of a quartz tube of a tube furnace, introducing carrier gas, and heating the tube furnace to a pyrolysis temperature; injecting an initiator into a first-section reaction zone of the tubular furnace, and decomposing to generate free radicals; the method comprises the following steps: feeding a waste plastic raw material into a first-section reaction zone of a tubular furnace, deeply depolymerizing volatile components generated by preliminary pyrolysis under the induction action of free radicals generated by decomposition of an initiator, blowing a product to a second-section reaction zone by carrier gas, and further cracking under the catalytic action of a molecular sieve; the initiator comprises nitropropane, and the molecular sieve catalyst comprises HZSM-5. According to the method, the in