In Situ and Ex Situ Catalytic Co-pyrolysis of Lignocellulosic Biomass and Plastics (Low-Density and High-Density Polyethylene) Using Spent FCC Catalyst

Catalytic co-pyrolysis of biomass and plastics (low-density and high-density polyethylene) was conducted utilizing spent fluid-catalytic-cracking catalyst. The effect of pyrolysis type (in situ vs. ex situ) on product yield and selectivity was tested at feed ratios of 1:2, 1:1, and 2:1 (w/w). The ex situ configuration improved the bio-oil quality and produced substantially high gas and low char yields than the in situ configuration. The bio-oil from ex situ processes had more oxygen-free monoaromatics with a maximum yield of similar to 29%C and similar to 26%C for low-density and high-density polyethylene at the biomass to plastic ratios of 2 and 1, respectively. The feed containing more biomass resulted in a higher selectivity towards monoaromatics (including benzene, toluene, and xylene) and polycyclic aromatic hydrocarbons, regardless of the configuration type. Compared to biomass pyrolysis, co-feeding plastics with biomass enriched the hydrogen content of the bio-oil with the ex situ processes producing more fungible products than the in situ processes. The effective H/C ratio in the bio-oils improved from similar to 0.19 to > 1.0 for the biomass-plastic mixtures compared to biomass pyrolysis alone. This is so as the plastics are hydrogen rich (H/C ratio of 2) compared to biomass, and the increased hydrogen availability during pyrolysis reactions improves the biooil quality and simultaneously reduces the char formation. [GRAPHICS] .