(399c) Simulation of the Conversion of Japanese Waste Biomass to Light Olefins: A Comparative Revision of the Effect of Biomass Chemical Composition in the Yield of Olefins in PRO/II

Japan has one of the best-stated and regulated waste management programs worldwide, befitting its geographical situation, shortage of disposal sites, sheltered resources, and environmental constraints. Only in 2020, a recycling ratio of 21% was endorsed with a disposal budget above USD 336 per waste ton. Still, Japan has a substantial capacity for Bioenergy and carbon capture, as its supply chain remains mostly non-renewable-based, ranking as the 4th largest consumer of petrochemicals and oil. Preliminary estimations with domestic wastes can forecast a theoretical substitution near 21% of the Japanese petrochemical olefins or BTX produced in 2020. A former revision on bio-waste availability suggests that Forest residue (leftover/thinning), rice waste (straw/husk), and cardboard waste are the most available lignified bio-waste in 2020. The last encourages a theoretical production of light olefins estimated at 2.16 Mt/y. While biomass for energy utilization may induce negative environmental effects, the production of biomass-based chemicals promotes an added-value approach, avoiding combustion and the production of biogenic CO2. The availability of Japanese waste hampers the conventional conversion via biochemical pathways like fermentation. For this reason, the thermochemical conversion of Biomass to Olefins (BTO) is recommended for lignified bio-waste, easily decomposed with pyrolysis or gasification. Still, the thermochemical conversion of Biomass to Olefins (BTO) remains on a conceptual level design. Industrially available technologies enclose the conversion via gasification, methanol synthesis, and catalytic methanol to olefins - MTO. Most revisions presented in the literature regarding BTO are oriented to the process design, by selecting and evaluating the platforms and chemistry concepts. Hence, the literature does not report an extensive revision of the role of feedstock in the process. Blocked studies compare the effect of different biomass only limited to the gasification or the methanol synthesis process. Still, no comprehensive revision is performed to date for the overall biomass to olefins bio-refinery.

The purpose of the current study is to quantify the effect of the biomass’ ultimate composition on the yield of light olefins. A comparative revision of the olefins yield with a simplified global reaction model of the conversion of BTO, and a detailed process simulation model in PRO/II does this valorization. Biomass included in the study with a global reaction model is cardboard and paperboard, rice husk, rice straw, forest residues of Japanese cedar, Hinoki cypress, and red pine. On the other hand, the biomass included in the PRO/II simulation model is forest residues of the Japanese cedar, Hinoki cypress, and red pine. A significant difference between the global reaction model and the numerical simulation in PRO/II is observed during the comparative revision. The global reaction model predicts a maximum theoretical yield of olefins near 36.1% g/gBM, compared to a more realistic yield in the PRO/II model near 23.5% g/gBM. The model in PRO/II includes semi-empirical kinetic models that emulate more realistic yields of syngas, methanol synthesis, or MTO. Still, the global reaction model allows fast and simple comparison of the performance with different biomass, predicting a high yield of olefins for the use of Japanese cedar and pine, over a lower yield for rice husk or cardboard. The difference in terms of the biomass ultimate composition is linked to the higher content of oxygen in the biomass, compared to the availability of hydrogen. The last behavior is coherent with the BTO definition as an elimination process of oxygen throughout the conversion steps. This revision suggests for further studies the use of biomass in BTO conversion with a lower content of oxygen.