Simulation of the Conversion of Japanese Waste Biomass to Light Olefins: Reducing Biogenic Emissions via CO2 Recirculation in the Water Gas Shift Reactor

Abstract

The significant availability of agricultural and forest residues in Japan impedes the traditional conversion through biochemical routes. In contrast to cellulose, lignin has a stronger chemical structure difficult to be decomposed via enzymatic or bacterial pathways. Thus lignified biomass waste can be easily converted through thermochemical degradation, as the aromatic structures of lignin can be break down with temperature between 550 - 900 °C. 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. Industrially available technologies enclose the conversion via gasification, methanol synthesis, and methanol to olefins. Unfortunately, this conversion pathway is also subject to CO₂ emissions during the gasification and the gas conditioning using water gas shift - WGS reactors. This study aims to assess the recirculation of the CO₂ produced in the WGS reactor while increasing the production of olefins and the process performance. This evaluation is performed with a dynamic process simulation in AVEVA™ PRO/II™. Preliminary results suggest a production of 200 kg of light olefins per ton of biomass, of while recycling CO₂ through the WGS reactor and capturing almost 70 % of the CO₂ emissions. The present study advises for further studies an extensive assessment of the WGS reactor operating conditions.