## 2 Materials and Methods
### Life Cycle Inventory (LCI)
#### 2.2.2 Woody Biomass Residues Based Process  
Glucose production from lignocellulosic biomass is still a novelty, which has been the focus of several studies over the last years. The most challenging issue that needs to be overcome is the pretreatment of the biomass, which has been proven to be crucial for the correct performance of the processes downstream. Intending to provide comparable results, the selected pretreatment step was the multistage (deacetylation-delignification-acid treatment) process reported by the National Renewable Energy Laboratory (NREL) in 2015, which is considered as a reference due to its wide scope. This study was published in a very complete report containing numerous operation details that allowed the conduction of our simulations for obtaining the necessary data for the life cycle inventory (LCI) [26]. After the pretreatment, an additional conditioning step was applied to increase the purity of cellulose and enhance the performance of the later hydrolysis step, as described in the patent document WO 2017/013684 Al [14]. This hydrolysis process was selected because it is based on an enzymatic pathway (which does not require subsequent neutralization steps) and makes use of filtration operations for purification steps (which generally consume less energy than other alternatives). An detailed description of these processes is provided below.  
As starting material, a generic woody biomass composition has been considered according to [PERSON] [27], having a moisture content of 30 wt% (see more details in Tables S1 and S2 of the Supplementary Information). Before the first reaction step, the biomass was crushed to produce wood chips, which were fed into a deacetylation tank, along with sodium hydroxide for lignin solubilization. The resultant black liquor was removed, and the retained mixture was forced through high-compression screw feeders, that discharge into a vertical acidification tank. Water steam and sulfuric acid were added for further oligomer disruption. The content was conveyed to a flash tank where the solubilizedlignin was condensed and eliminated before a final neutralization stage with ammonia gas. A more detailed description can be found in NREL's study [26]. Although, as previously mentioned, when any allocation method was applied, it must be noted that we had considered hemicellulose carbohydrates to be transformed into soluble sugars under the pretreatment conditions, leading to different monomeric products at the end of the process.  
The pretreated biomass was then submitted for conditioning, undergoing a three-step acid-alkali-acid treatment to increase cellulose purity (Figure 3). The first acid treatment was conducted in the presence of a 2 wt% sulfuric acid aqueous solution at 393 K and atmospheric pressure for 15 min. This stage was intended to partially affect insoluble lignin and xylan, and the result was a slurry, which was forced through a mechanical filter resulting in two streams. The undesired liquid fraction was removed and sent to wastewater treatment, whereas the solid fraction (containing at least 80% pure cellulose) was treated with sodium hydroxide (0.5 wt%) for 30 min to undertake a second reaction under similar conditions to those above described for the first stage. After a second separation operation, the third cycle, a new acid treatment with 2 wt% sulfuric acid solution, took place, yielding a final aqueous suspension (7 wt%) containing highly-pure cellulose (98 wt%).