**2. CPH valorization routes and technological approaches into chemical platforms, fuels, and low value products**

To date, conventional valorization routes for transforming CPH to specialty chemicals occur either *via* biochemical, thermochemical, or physicochemical techniques. A combination of these techniques is also possible, given that lignocellulosic biomass usually requires pretreatment especially before biochemical conversion.

#### **2.1 Biochemical transformation of CPH into fuels**

Biochemical transformation of renewable raw materials involves the use microorganisms as catalyst to transform biomass into valuable products. It is often regarded as a cheaper approach for converting biomass to chemical, energy, and fuels. However, due to the recalcitrant nature of lignin component in biomass, the use of microbes to transform crude biomass into valuable products is often challenging and difficult. In this context, it is imperative to pretreat the biomass raw material in order to render cellulose and hemicellulose susceptible to microbial action. The pretreatment processes may be physical, thermochemical, biological, or physicochemical. The nature of pretreatment approach dictates the types of the intermediate chemical that would be obtained for further conversion to final product. The main biochemical routes that have been investigated using CPH as raw material are fermentation and anaerobic digestion.

#### *2.1.1 Anaerobic digestion of CPH*

Anaerobic digestion (AD) is a sequence of processes by which microorganisms break down biodegradable material in the absence of oxygen. AD basically occurs in three steps: decomposition or hydrolysis of biomass, followed by conversion of treated biomass to organic acids, and finally conversion of acids into methane gas. The main product of AD is biogas which contains methane, carbon dioxide, and some traces of hydrogen sulfide which is one of the main sources of renewable energy. The process also produces an aqueous mixture consisting of microorganisms involved in the degradation. Large volumes of CPH generated and its composition makes it a viable candidate for AD biogas production.

In 2018, Acosta and co-workers [12] investigated the production of methane and biogas yields from CPH and compared it to other agricultural residues, to evaluate the quality of the biomass raw material as a new feedstock for biogas production. The authors concluded that 50% of organic matter from CPH was transformed to biogas with 60% yield of methane. Dry AD was the preferred process choice for the authors because it gave the highest yields of methane and also, the operating conditions were stable [12].

In another interesting work, Antwi et al. [13] investigated the potential of valorizing CPH *via* anaerobic digestion and the impact of hydrothermal pretreatment on biogas yield. They compared the biogas yield and methane content of untreated anaerobically digested CPH to those obtained from the hydrothermally pretreated CPH at different severity levels. Based on their results they concluded that AD is an effective process of converting CPH to fuels. Furthermore, the impact of the pretreatment is diverse in that biogas yield increased for CPH treated at low severity levels up to 3.0. Hydrothermal pretreatment at severity levels above 3.0 lead to inhibitions in the AD process that lowered the biogas yield.

Several reports on the valorization of CPH or cocoa related residue to biogas *via* AD has proven that to be an effective approach, however, a form of pretreatment (physical, thermochemical, biological, or physicochemical) of the biomass is required to separate lignin from cellulose and hemicellulose [5, 14–17].

#### *2.1.2 Fermentation of CPH*

Fermentation is the conversion of sugars contained in biomass hydrosylate to specialty chemicals using microbes. The type of microbe used dictates the fermentation pathway as well as the end products. The conversion of CPH to bioethanol, bio-butatnol, and propanoic acid by fermentation reported in literature has been highlighted below.

Shet et al. [17] hydrolyzed CPH with HCl to release reducing sugars under optimized conditions (8.36% W/V of CPH, 3.6 N HCl, and 7.36 hours) using response surface methodology (RSM). The hydrosylate was neutralized using 5 N NaOH followed by fermentation to produce bioethanol. The inoculum was *Pichia stipites* at 2% V/V. After 72 hours of fermentation, bioethanol was distilled from the broth at a concentration of 2 g/L. They demonstrated that CPH to ethanol conversion is feasible and that CPH offers a cheaper and renewable feedstock for ethanol production. A similar work was done by Samah and co-workers [18], where CPH was hydrolyzed with HCl, H2SO4, and HNO3 at different concentrations (0.25, 0.50, 0.75, 1.00, and 1.25 M). They were further heated to 75 and 90°C for 2 and 4 hours. The highest glucose content of 30.7% W/V was obtained for CPH samples treated with 1.00 M of HCL at 75°C and 4 hours. The hydrosylate was then fermented using *Saccharomyces cerevisiae* for 48 hours at room temperature to obtain a maximum ethanol concentration of 17.3% V/V after 26 hours of fermentation.

Hernández-Mendoza et al., 2021 on the other hand performed alkaline hydrolysis on CPH and examined the effect of NaOH concentration, residence time, and temperature using a central composite design (CDD). The solid fraction was examined with X-ray diffraction (XRD) and scanning electron microscopy (SEM) in order to investigate morphological changes. It was further subjected to enzymatic hydrolysis which optimized the enzyme and solid loadings to convert cellulose to reducing sugars. The yeast *S. cerevisiae* was applied to ferment the hydrosylate. The optimum condition for the alkaline hydrolysis process occurred at 5% W/V NaOH

*Conventional and Unconventional Transformation of Cocoa Pod Husks into Value-Added… DOI: http://dx.doi.org/10.5772/intechopen.102606*

for 30 minutes at 120°C which led to an increased in the cellulose content of CPH to 57 ± 0.25% relative to that of the untreated sample of 27.68 ± 0.15%. SEM revealed changes in porosity and structure of CPH, whilst XRD showed increase in crystallinity. Enzymatic hydrolysis yielded 66.80 g/L of reducing sugars of which 80.74% were consumed during fermentation producing 18.06 g/L of ethanol in 24 hours. They concluded that CPH is a promising feedstock for bioethanol production [19].

Propionic acid production from CPH was reported for the first time by Sarmiento-Vásquez et al. [20]. In their work, alkaline and enzymatic treatment is conducted with 2.3% W/V NaOH and 2.4% V/V Cellic® CTec2, respectively to convert CPH to fermentable sugars such as glucose to a maximum yield of 275 mg glucose/g CPH. Subsequently 7.5 g/L CPH hydrosylate is fermented with *Propionibacterium jensenii* (DSM 20274) in the presence of 7.5 g/L of glycerol. A maximum propionic concentration of 10.28 ± 1.05 g/L after 75 hours of fermentation.

Sandesh et al. [21] successfully produced acetone, bio-butanol, and ethanol from inductive assisted H2SO4 hydrolyzed CPH using *Clostridium acetobutylicum*. A product distribution of 5.04 ± 0.32 g/L of acetone, 11.73 ± 0.84 g/L butanol, and 1.43 ± 0.04 ethanol is reported to have been obtained after 312 hours of fermentation.

These results are a demonstration of the potential of CPH as a cheap feedstock for the production of biochemicals *via* fermentation techniques after different pretreatment approaches have been applied to the CPH biomass to convert it to fermentable sugars.

#### **2.2 Thermochemical approaches**

Thermochemical biomass conversion approach involves all processes in which heat is used to transform biomass in the solid form to other states in the presence or absence of oxygen. Processes that fall under this category are direct combustion, gasification, pyrolysis, hydrothermal liquefaction, and torrefaction. This section examines how thermochemical conversion processes have been applied in CPH valorization.

#### *2.2.1 Direct combustion*

In direct combustion, biomass is burnt in ovens, kilns, fluidized bed combustors, furnaces with excess oxygen or air to obtain gases and ash. The combustion chambers are usually operated at temperature above 900°C. Gases and ash are the key products. The ash has been found to contain 40% potash which consists of 43% potassium carbonate and 27% potassium hydroxide. This is the process soap-makers in most West African countries harness potash from CPH to produce soft soap known locally as *alata samina* [22]. These CPH potash soap have been found to contain superior properties such as higher solubility, lathering capacity, cleansing power, and consistency compared with those produced with chemical KOH [23]. Furthermore, CPH ash has also been applied as fertilizer. Studies shows that replacing about 50% of conventional NPK fertilizer with CPH ash has had positive impact on nutrients uptake by maize plants and grain yield [24]. It has had similar effect on soil fertility, fruit growth, and yield in tomato production [25]. CPH ash obtained in a furnace at 650°C for 4 hours was evaluated by [26] as a heterogeneous catalyst for the transesterification of soya bean oil to biodiesel. Their results demonstrated that CPH ash is a superior catalyst for generating high yield of biodiesel with quality and engine performance close to that of diesel from petroleum.

#### *2.2.2 Pyrolysis*

In pyrolysis biomass is thermally decomposed in an inert atmosphere at elevated temperatures. The biomass is usually converted to volatile products with solid residue called char where the proportion of each fraction depends on the conditions of pyrolysis that the biomass was subjected to. The volatile fractions are usually condensed to obtain the liquid (bio-oil) and non-condensable gaseous fractions. Operating parameters such as reaction temperature, pressure, catalysts, hot vapor residence time, solid's residence time, etc., affect the overall process performance. The conditions of pyrolysis fall into three categories namely slow pyrolysis, fast pyrolysis, and flash pyrolysis. In slow pyrolysis, the temperature of the biomass is raised to about 500°C at low heating rates with long residence times. The solid char is the main product and it is the main route of producing charcoal which can used as fuel, activated carbon, soil conditioners, and feedstock for producing chemicals. On the other hand, in fast and flash pyrolysis, the liquid fraction or bio-oil is the preferred product. In fast pyrolysis, temperatures of about 500°C and short vapor residence time of about 2 seconds are typical to generate bio-oil from biomass. Flash pyrolysis is similar to fast pyrolysis except that the residence time is shorter in the former [27].

Pyrolysis is the most widely exploited biomass to liquid (BTL) conversion route in that the crude bio-oil can be directly used in boilers and turbines to generate electricity and heat as well as feedstock for synthesizing fuels, base, and fine chemicals [28]. By this technology, bio-oils that of high value and substitute for fuels from non-renewable sources can be produced [29]. Tsai and co-worker [30] demonstrated that slow pyrolysis of CPH produces bio-chars of more than 60% carbon content and a calorific value greater than 25 MJ/kg, dry basis at temperatures between 190 and 370°C for 30–120 minutes. They concluded that though this type of biochar exhibited lignite-like feature, it is not suitable for use as fuel in boilers due to the high potassium content. Several researchers have applied this process to CPH and have generated similar products [31–33].

CPH was pyrolyzed under fast pyrolysis conditions at temperatures 550–600°C by [29] for 2–4 minutes to yield 58 wt.% bio-oil, 30 wt.% biochar, and 12 wt.% noncondensable gases. Analysis of the bio-oil shows it contained a complex mixture of carboxylic acids and ketones with 9,12-octadecadienoic acid being the most abundant.

In another work by Mansur et al., the authors [2] reported the possibility of upgrading pyrolysis oil obtained from CPH *via* the use of heterogeneous catalysis. Firstly, they pyrolyzed CPH at 500°C for 50 minutes to yield pyrolysis oil which contained several chemical compounds including benzenediols, ketones, carboxylic acids, aldehydes, furans, heterocyclic aromatics, alkyl benzenes, and phenols. This oil was subjected to catalytic upgrade using ZrO2-FeOx where ketonization, selective oxidation, and demethoxylation reactions occurred and selectively yielded acetone, 2-butanone, phenol, cresol, xylenol, and ethyl phenol.

Prior to pyrolysis, it is imperative to pretreat the biomass by sun drying, oven drying to avoid moisture saturation, and mechanical comminution to increase the surface area for effective pyrolysis.

#### *2.2.3 Gasification*

Gasification is a thermochemical biomass conversion process which occurs at elevated temperatures above 700°C in a limited amount of oxygen. Usually 70–80% is transformed to synthesis gas (CO and H2) and the remainder is biochar. It is possible

*Conventional and Unconventional Transformation of Cocoa Pod Husks into Value-Added… DOI: http://dx.doi.org/10.5772/intechopen.102606*

to obtain some amount of bio-oil if the condition is favorable. To maximize the yields of synthesis gas and improve on the overall efficiency of the process, supercritical water, and catalyst is used [27]. The synthesis gas can be transformed to fuels and myriad of chemicals via Fischer-Tropsch synthesis [34]. CPH has been converted to gaseous products of varying composition by gasification. For instance, Gunasekaran et al. [35] investigated the numerical and experimental potential of CPH gasification in an open-core gasifier. According to their results, the composition of CO, H2, and CH4 in the producer gas was found to be 20–24%, 12.0–16.5%, and 2.0–3.2%, respectively for the conditions that were tested. The conversion efficiency and cold gas efficiency were determined to be 82 and 38%, respectively. Further, the predicted performance parameters and temperature distribution were found to be at par. Thus, CPH was found to be a promising raw material for an open-core gasifiers.

The application of recycle system on a CPH gasification in a fixed-bed downdraft reactor was carried out by Pranolo and co-workers [36]. The aim was to produce low tar fuel gas from CPH using recycle stream consisting of CO, H2, CO2, and CH4. They successfully reduced the tar content in the product gases up to 62% at temperatures ranging from 750 to 780°C. Therefore, the gas may be used as a substitute fuel for electricity generation.

#### *2.2.4 Physicochemical routes*

The valorization of CPH by physiochemical approach has mainly been by solid phase extraction or leaching in which solutes are removed from a solid by a liquid solvent [37]. Such processes have been applied in the extraction of phytochemicals and pectin from CPH. Phytochemicals are natural functional foods that possess a rich reservoir of bioactive components and nutraceuticals. Nutraceuticals was coined by Dr. Stephen De Felice and is a derivation from words "nutrition" and "pharmaceuticals." Phytochemicals are mainly foods or parts of foods that provide medical or health benefits including the prevention and treatment of diseases. There has been rapid increase in the consumption of plant-derived bioactive. Plants produce these chemicals to protect themselves but recent studies have shown that these chemicals can protect humans, animals, and other plants against diseases compound [38].

Rachmawaty et al., 2018 studied the extraction of bioactive components from CPH and the in vitro antifungal activity assay against the pathogenic fungus *Fusarium oxysporum*. The *F. oxysporum* is a deadly fungus that can cause diseases in nearly every agriculturally important plant. In the study, CPH was dry milled using a grinder into powder. Two solvents, acetone-water (7:3) and 70% ethanol was used to extract the phytochemicals. A solvent to sample ratio of 10:1 was used such that 200 ml of solvent was used for 20 g of CPH sample. The extract was found to contain alkaloids, flavonoids, tannins, and saponins, and triterpenoids which indicates the antimicrobial potential of the CPH extract. GC-MS analysis revealed four major components in the acetone solvent namely isopropyl myristate, benzenedicarboxylic acid, 9-octadecenoic acid (Z)-, methyl ester and octadecanoic acid, methyl ester. For the ethanol solvent however, three main components were found namely octadeca methyl-9,12-dienoate; 9-octadecenoic acid (Z)-, methyl ester; hexadecanoic acid, 15-methyl-methyl ester.

The acetone extract recorded the highest phenolic content and also a higher anti-fungal activity than the ethanol extract. Agar diffusion method was employed for antifungal testing and it showed that the extract was able to inhibit the fungal growth therefore leading to the conclusion that the CPH extract has great potential as a natural fungicide.

Pectin, a family of complex, acid-rich polysaccharides found in plant cell wall have been recovered from CPH by this approach. They have been extensively applied as gelling and stabilizer in cosmetics, food, and pharmaceuticals. They have the ability to reduce serum cholesterol, glucose, cancer incidence, and improved immune response in humans [39].

Pectin recovery from CPH was studied by Valladares-Diestra et al. [40] using citric acid hydrothermal treatment of CPH with concomitant production of xylooligosaccarides via enzymatic hydrolysis of the solid fraction after extraction. An optimum condition of 120°C, 10 minutes, and 2% W/V was employed for the recovering pectin. An amount of 19.3% of the biomass was recovered as pectin. They concluded that the prospects of implementing this novel method for the extraction of valuable chemicals such as pectin is very high.

Vriesmann et al. [39] optimized the variables affecting the nitic acid extraction of pectins from CPH using RSM. The optimum extraction condition was determined as pH 1.5, a temperature of 100°C, and time of 30 minutes. By these conditions a yield and uronic acid (UA) content (representing pectin content) of about 9.5 and 80%, respectively were predicted. However, experimental results gave a yield of 9.0 ± 0.4% and UA content of 66%. The predicted and experimental yield values were in close agreement, on the contrary, experimental UA content value was 17.5% lower than the predicted. This disparity was attributed to the low quality of the model for used the prediction. They further characterized the pectin a homogalacturonan highly esterified and acetylated one with some rhamnogalacturonan insertions.

Recently, Vriesmann and de Oliveira Petkowicz [41] compared the use of nitric acid and boiling water for the extraction of pectin. The pectins obtained from both extraction process was similar and identified as low methoxyl type. Rheological analysis suggests that both formed gels at low pH in spite of their high acetyl content therefore, the pectin can be used in acidic products.

### **3. Unconventional CPH valorization processes**

Recently, processes that are considered green have been utilized to extract bioactive chemical from biomass feedstocks. These processes are gaining popularity due to their inherent benefits such lower temperature, less activation time, and higher carbon yield. Microwave, ultrasound as well as super and subcritical fluid extraction have been applied to obtain valuable chemical from CPH and is discussed in this section.

#### **3.1 Microwave-assisted valorization of CPH**

Microwave has been utilized in recent times to extract biochemicals instead of conventional processes as uniform heating, time, and solvent savings [42–44] are the main advantages of this process. Additionally, it has been found to improve the accessibility and reactivity of cellulose when used to pretreat lignocellulosic biomass. Moreover, subsequent enzyme action is heightened [43]. This is the most widely applied unconventional process for CPH valorization.

In the work of Mashuni et al., 2020, microwave was used to assist the extraction of phenols from CPH using 85% V/V ethanol as solvent. The microwave heating power was varied from 100 to 300 W whilst the extraction time spanned 5–30 minutes. Using the Folin-Ciocalteu method with gallic acid as a standard, the total phenol

*Conventional and Unconventional Transformation of Cocoa Pod Husks into Value-Added… DOI: http://dx.doi.org/10.5772/intechopen.102606*

content of CPH was determined. The highest amount of phenol content was found to be 853.67 mg/L after 20 minutes of extraction at 200 W of microwave power. Upon characterizing the extract with GC-MS, it was revealed that the phenols present are butylhydroxytoluene; 6,6′-methylenebis(2-(tert-butyl)-4-methyl-phenol); 3-methoxy-2-((*2E*,*6E*)-3,7,11-trimethyl-dodeca-2,6,10-trienyl) phenol; and 7-hydroxy-3-(1,1-dimethylprop-2-enyl) coumarin. They concluded that microwave assisted extraction (MAE) is a promising technique for the extracting phenols quickly and efficiently [45].

Novel research was conducted by Nguyen and co-workers [42] where they extracted saponin from CPH *via* MAE using methanol as solvent. They used RSM (CCD) to identify the optimum parameters for the process. According to their findings, the optimum MAE conditions for obtaining the maximum saponin content and extraction efficiency from dried CPH were 85% methanol concentration, 40 minutes extraction time, 600 W microwave power, 6 seconds/minute irradiation time, and 50 ml/g solvent to sample ratio. The saponin content and extraction efficiency determined under these conditions were 69.9 mg escin equivalents/g dried sample and 71.1%, respectively. Thus, the CPH has a huge potential as a source of bioactive compounds for used in the nutraceutical and functional foods industries and to harness these compounds the optimum MAE conditions should be applied for best results. MAE was applied to isolate pectin from CPH using oxalic acid by Pangestu and colleagues [46]. In their work, they used RSM to investigate how pH, liquid to solid ratio (L/S), and irradiation time interact to affect the quantity of pectin isolated. A pH of 1.16, L/S of 25, and 15 minutes of irradiation were found to give a maximum yield of 9.64%. They emphasized that this route reduced the extraction time by 2–6 times. Further the L/S ratio can be minimized without considerable impact on the results. MAE was concluded as a powerful technique for isolating pectin using a cheaper and safer acidifying agent such as oxalic acid. Villota et al. [47] carbonized H3PO4 and KOH activated CPH via microwave assisted pyrolysis at 450°C for 5 minutes. The effect of H3PO4 and KOH on the activation of char from CPH and in all cases, H3PO4 activated carbon was observed to have higher yield and better textural properties (BET surface area = 1237.47 m2 /g, pore volume = 1.11 cm3 /g, and mesoporous) relative to that activated with KOH which exhibited severe material loss as well as low strength. Microwave assisted pretreatment of CPH has been applied by several researchers. A summary is presented in **Table 1**.

#### **3.2 Ultrasound-assisted valorization of CPH**

This process was implemented in the work of Hennessey-Ramos and colleagues, 2021 to extract pectin from CPH. RSM was used to determine the optimum operating conditions that is 6.0% feedstock concentration, 40 μL/g enzyme, and 18.54 hours on stream. Experiments involving three processes for extracting pectin namely acid, ultrasound-assisted and enzymatic extraction were conducted and compared. The results are summarized in **Table 2**.

From the results enzymatic extraction of pectin gave the best results for pectin yield followed by ultrasound-assisted citric acid extraction. The low GA content was attributed to duration (45 minutes) and temperature (60°C) of the process. They asserted that industrial operations above 60°C for ultrasonic assisted citric acid pectin extraction with the aim of increasing GA content would not be feasible owing to the inherent advantage of low temperature operation for such technologies. In the extraction of microcrystalline cellulose from CPH, it was pretreated with alkali followed


#### **Table 1.**

*Various microwave-assisted pretreatment of CPH.*


#### **Table 2.**

*Comparative analysis of chemical, ultrasound assisted, and enzymatic pectin processes.*

by ultrasonication. Ultrasound applied after alkaline pretreatment of the feedstock brought about cavitation action that helped to effectively remove fibril aggregates from the microcrystalline cellulose. A sonication time of 60 seconds and two cycles of the ultrasonication process considerably reduced the particle size of the microcrystalline cellulose to 280 nm [51].

#### **3.3 Super and subcritical fluid extraction of biochemicals from CPH**

Long extraction periods, low yield and quality of extracts, and loss of volatile compound are among many limitations of traditional extraction processes that has warranted the development of novel and green processes that overcome these limitations. Super critical and subcritical fluid extraction are among such processes that are considered efficient and time-economic [43, 52–54]. In a recent study on the extraction of phenols from CPH using supercritical CO2, Valadez-Carmona et al. [7] employed a Box-Behnken design to maximize the process variables that is temperature, pressure, and co-solvent. The optimum conditions obtained were 60°C, 299 bar, and 13.7% ethanol. By this approach, the extraction time was lowered even though the yield was low (0.56%), the quality of the extracts was improved whilst the loss of volatile compound was minimized. The highest total phenolic compounds (TPC) were found to be 12.97 mg GAE/g extract whereas the total antioxidant capacity was 0.213 mmol TE/g extract. These findings demonstrates that supercritical CO2 extraction is a promising technique that can be exploited for the isolation of natural

*Conventional and Unconventional Transformation of Cocoa Pod Husks into Value-Added… DOI: http://dx.doi.org/10.5772/intechopen.102606*

antioxidants from CPH for use in food, cosmetic, or pharmaceutical products. Another interesting work was published by Muñoz-Almagro and co-workers [55] where they compared conventional and subcritical water extraction of pectin from CPH. The latter process is a technique in which water provides H<sup>+</sup> and OH− ions at high pressure and temperature for dissolving both polar and non-polar compounds. At high temperatures the hydrogen bonding in water is weakened thereby decreasing the dielectric constant value and water polarity which consequently lowers the energy required for dissociation of water molecules in solute-matrix interactions and extraction efficiency is increased [55]. In the subcritical water extraction process, a pectin yield of 10.9% as opposed to 8% obtained using conventional extraction with citric acid as solvent. Characterization of the pectin showed that high molecular weight pectin (750 kDa) was preferentially extracted during the subcritical operation. These green techniques have been shown to possess high selectivity towards targeted compounds and potential for CPH valorization.

### **4. Future perspective**

Although several transformation techniques have been investigated for the conversion of CPH to valuable products, there is still a need to develop efficient and sustainable approaches for a holistic CPH biomass valorization process. In this context, the development of cutting-edge technologies that can efficiently transform these hitherto waste materials generated from cacao into useful chemicals that could potentially improve the global value chain of cacao production, is crucial and highly sort after. Although of interest, the uncontrolled co-production of char and gaseous products limits the overall yield of bio-chemicals so-obtained, and thus the overall efficiency of this approach. Being able to fractionate these lignocellulosic biomass waste into valuable chemicals in a selective fashion is highly desirable from economic and environmental considerations, but it remains a very important scientific challenging task due to scientific bottlenecks such as: (i) recalcitrance of lignocellulosic biomass to hydrolysis, often requiring high activation temperatures which are not compatible with the stability of sugars, the main components of lignocellulosic biomass waste, and (ii) high dilution ratio to prevent recombination reactions (for instance caramelization of monomeric sugars) leading to the unwanted formation of tar-like materials. In order to overcome such scientific hurdles, researchers should consider the coupling of mechano-catalytic technology to first release sugars contained in CPH, which can be achieved without the need of any solvent, translating into efficient and environmentally friendly synthesis approach, and a pyrolysis process to valorize lignin, the co-product of the CPH fractionation after the mechano-catalytic step.
