Methanol production from biomass: Sorption-enhanced reforming and methanol synthesis for decentralised biogas valorisation using Aspen Plus.

This study proposes a sorption-enhanced biorefinery concept for decentralised methanol production from raw biogas, integrating Sorption-Enhanced Steam Reforming (SESR) and Sorption-Enhanced Methanol Synthesis (SEMS) within a unified thermodynamic framework. The process combines in situ CO 2 capture during reforming with water removal during synthesis, both mediated by a circulating CaO loop, in order to reduce biogas upgrading requirements and enhance carbon utilisation under idealised equilibrium conditions. Thermodynamically consistent equilibrium models were implemented to compare three process configurations under identical boundary conditions: fully integrated SESR–SEMS (Case Study 1), SESR coupled to conventional methanol synthesis (Case Study 2), and a green- H 2 + CO 2 hydrogenation route (Case Study 3). For a representative 1 000 Nm 3 h −1 raw biogas feed, the equilibrium-based SESR–SEMS configuration predicts a crude methanol yield of 34.13 kmol h −1 (0.927 kg m −3 ), an overall carbon conversion efficiency to methanol of 51.8%, and a carbon capture efficiency of 90.4%. The corresponding specific energy demand is 2.42 kWh m −3 , higher than that of SESR coupled with conventional synthesis (1.52 kWh m −3 ) owing to the additional regeneration duty associated with the sorbent loop. Secondary equilibrium indicators suggest high theoretical hydrogen purities and strong thermodynamic driving forces for CO 2 conversion and H 2 O removal within the SEMS reactor. Sensitivity analyses on gas hourly space velocity, steam-to-carbon ratio, and synthesis pressure identify thermodynamic operating regions in which SEMS suppresses reverse water–gas shift and favours increased single-pass methanol productivity. The model is intentionally equilibrium-based and does not account for reaction kinetics, catalyst deactivation, transport limitations, or transient reactor behaviour. Accordingly, the reported performance metrics should be interpreted as thermodynamic upper-bound estimates intended to define comparative process envelopes and guide future rate-based modelling, pilot-scale validation, and techno-economic assessment of sorption-enhanced biomethanol systems. Overall, the results indicate that sorption-enhanced process integration may offer favourable thermodynamic potential for conversion of distributed biogas resources into liquid fuels.