βI	Mass concentration of i
$\text{(}{p}_{\text{i}}^{\text{G}}-p_{\text{i}}^{\text{L}}\text{)}$	Driving force of mass transfer expressed as difference in partial pressure of i (bar)
(c* − c)	Difference of saturation concentration and actual concentration of a compound at process conditions (mol L−1)
D1.5	Inner diameter of reactor vessel in 1.5 L-scale (mm)
d1.5	Stirrer diameter in 1.5 L-scale (mm)
D2.5	Inner diameter of reactor vessel in 2.5 L-scale (mm)
d2.5	Stirrer diameter in 2.5 L-scale (mm)
E	Consumed amount of substance divided by the total fed amount of substance (%)
Hi	Henry’s solubility coefficient of i (M bar−1)
hl 2.5	Filling level in 2.5 L-scale (mm)
kLa	Volumetric mass transfer coefficient (s−1)
$\dot{n}{V}_{\text{L}}^{-1}$	Volumetric amount of substance flow rate (mmol min−1 L−1)
$P{V}_L^{-1}$	Volumetric power input (W L−1)
$p_{{\text{CO}}_2}$	Partial pressure of carbon dioxide (bar)
$p_{H_2}$	Partial pressure of hydrogen (bar)
${\dot{V}}_{\text{g}}{V}_L^{-1}$	Volumetric gas flow rate (vvm)
xi	Amount of substance ratio calculated by xi = ci/Σci (−)
YP/S	Mass based product yield per substrate (g g−1)