Comparison of 4,4 '-Dimethylbiphenyl from Biomass-Derived Furfural and Oil-Based Resource: Technoeconomic Analysis and Life-Cycle Assessment

Replacing oil-based toluene with biomass-derived furfural for 4,4'-dimethylbiphenyl (DMBP) production can pave the way for sustainable polyester manufacture. This work compared the economic and environmental performances of two conceptual designs of 4,4'-DMBP production. The first toluene-based route consists of toluene alkylation to (methylcyclohexyl)toluene (MCHT), MCHT dehydrogenation to DMBP, and isomerization of lower-valued 3,3'-DMBP. The renewable furfural-based route includes hydrogenation of furfural to 2-methylfuran (MF), oxidative coupling of MF to 5,5'-dimethylfuran (DMBF), and tandem Diels-Alder dehydration of 5,5'-DMBF to 4,4'-DMBP. The reaction conditions are optimized to achieve a more economically feasible process using furfural feedstock. At a scale of 83 kmol/h feedstock, the 4,4'-DMBP minimum selling price of the furfural-based route is $3044/t, while that of the toluene-based route is $2488/t. The feedstock and 3,4'-DMBP isomer prices are identified as critical parameters for the economic evaluation by sensitivity analysis. A "cradle-to-gate" life-cycle assessment confirms that furfural-based DMBP production emits significantly fewer greenhouse gas (5.00 kg CO2 equiv/kg DMBP) as compared to the toluene-based counterpart (8.28 kg CO2 equiv/kg DMBP).