Production of combustible fuels and carbon nanotubes from plastic wastes using an in-situ catalytic microwave pyrolysis process

Abstract

This study performed in-situ microwave pyrolysis of plastic waste into hydrogen, liquid fuel and carbon nanotubes in the presence of Zeolite Socony Mobil ZSM-5 catalyst. In the presented microwave pyrolysis of plastics, activated carbon was used as a heat susceptor. The microwave power of 1 kW was employed to decompose high-density polyethylene (HDPE) and polypropylene (PP) wastes at moderate temperatures of 400–450 °C. The effect of plastic composition, catalyst loading and plastic type on liquid, gas and solid carbon products was quantified. This in-situ CMP reaction resulted in heavy hydrocarbons, hydrogen gas and carbon nanotubes as a solid residue. A relatively better hydrogen yield of 129.6 mmol/g as a green fuel was possible in this process. FTIR and gas chromatography analysis revealed that liquid product consisted of C13+ fraction hydrocarbons, such as alkanes, alkanes, and aromatics. TEM micrographs showed tubular-like structural morphology of the solid residue, which was identified as carbon nanotubes (CNTs) during X-ray diffraction analysis. The outer diameter of CNTs ranged from 30 to 93 nm from HDPE, 25–93 nm from PP and 30–54 nm for HDPE-PP mixure. The presented CMP process took just 2–4 min to completely pyrolyze the plastic feedstock into valuable products, leaving no polymeric residue.

Fabrication of Fe–Zr, Co–Zr, and Ni–Zr Catalysts to Boost CNTs Synthesis from Plastic Wastes and the Electrocatalytic Oxygen Evolution Reaction

“…In addition, three kinds of diffraction peaks were detected in Fe–Zr/2–700 and Fe–Zr/2–800 XRD patterns, which proved the formation of new crystal phases, and were labeled as C, Fe 3 C, and Fe, respectively. (1) The one at 26.3° was attributed to the graphitic carbon (111) crystal plane (JCPDS PDF#75-0444). − This diffraction peak of Fe–Zr/2–800 was stronger than that of Fe–Zr/2–700, which proved the higher yield of CNTs and was consistent with the TG and SEM results. (2) The one at 44.7° was attributed to metallic Fe (110) crystal plane (JCPDS PDF#87-0722). , It indicated that PE pyrolysis gases facilitated the reduction of Fe 2 O 3 to metallic Fe during CNTs synthesis.…”

Pioneering Aromatic Generation from Plastic Waste via Catalytic Thermolysis: A Minireview

“…The amount of aromatic hydrocarbons decreased from 53.7 to 0.3% after 30 min of run time. 154 Ma et al performed copyrolysis of biomass (corn cob) and PS by thermal degradation using a MW oven at 450 °C. A synergistic effect was observed during copyrolysis at a biomass/PS ratio 1:2, with a liquid yield of 52.3% and aromatic selectivity of 95%.…”

“…The activated carbon was used to absorb the MWs. The amount of aromatic hydrocarbons decreased from 53.7 to 0.3% after 30 min of run time . Ma et al performed copyrolysis of biomass (corn cob) and PS by thermal degradation using a MW oven at 450 °C.…”

Co‐, Ni‐, and Cu‐Doped Fe‐Based Catalysts for the Microwave‐Assisted Catalytic Pyrolysis of Polyethylene

“…[21][22][23] Various researchers have investigated catalysts for the microwave-assisted catalytic pyrolysis of polyethylene to enhance the product yield and selectivity. [24] Irfan et al [25] investigated the effects of a zeolite catalyst (ZSM-5) on the in situ microwave-assisted pyrolysis of high-density polyethylene (HDPE) at intermediate temperatures of 400-450 °C, achieving a hydrogen production rate of up to 18.5 mmol/ g plastic . Shen et al [26] prepared Fe-based catalysts with different microwave absorption properties using various catalyst supports such as activated carbon, silicon carbide, and silica.…”