Nanocellulose is one of the most important lignocellulose-derived value added products in the emerging market of biobased polymers. Its isolation upon employment of milder, environmentally friendly processes is particularly attractive. Biocatalysis is a promising approach due to targeted and substrate-specific activity, selectivity, mild and non-toxic chemistry. Endoglucanases are the most exploited enzymes for the production of nanocellulose due to their potential to remove the less ordered amorphous regions from cellulose fibers, leaving intact the more organized, crystalline areas, thus facilitating the nanocellulose isolation without altering the cellulose surface chemistry. Moreover, accessory activities including xylanases and other hemicellulose-acting enzymes hold a key role for the isolation of nanocrystalline cellulose. The newly discovered lytic polysaccharide monooxygenases (LPMOs) are also gaining attention due to their implication in nanocellulose production. Within this context, we report the heterologous expression and production of a novel fungal C1-acting AA9 LPMO from Thermothelomyces thermophila. The enzyme was biochemically characterized for its activity on different polysaccharide substrates, while different electrochemically active compounds were tested as electron donors. The formal potential of the of the Cu(II) center in the active site of the LPMO was determined with the use of large amplitude Fourier Transform alternating current cyclic voltammetry(FTacV). Finally, the application of the enzyme together with other glycoside hydrolases on nanocellulose isolation from beechwood was studied. Starting with an initial mild oxidative organosolv pretreatment, efficient delignification was achieved, leaving behind a cellulose-rich solid fraction. An enzymatic treatment step with LPMO was then applied, followed by different sequential hydrolysis steps with cellulolytic and hemicellulolytic enzymes, thus enabling a fine-tuning of all activities with the aim to shed light on the contribution of different enzymes in each step. Both commercially available enzyme cocktails and a combination of different monoenzymes with specific activities were tested in order to assess their individual effects.

Acid-catalyzed carboxymethylation of alcohols is an emerging organic transformation that has grabbed the attention of scientific community in recent years. In the present study, sulfonated mesoporous polymer (MP-SO₃H) is presented as a highly active solid acid catalyst to convert a wide range of alcohols into alkyl methyl carbonates. The remarkable catalytic activity of MP-SO₃H is comparable to that of reported homogeneous acid catalysts. A good correlation was established between the catalytic activity and textural properties of the material. An exceptional catalytic activity of MP-SO₃H was observed for DMC mediated carboxymethylation of bio-derived alcohols which is unmatchable to conventional resins and zeolites. This superior activity of MP-SO₃H is ascribed to its intrinsic mesoporosity, high acid strength and uniform coverage of surface area by active sites. The catalyst is recyclable, resistant towards leaching and can be used in successive runs without losing the original activity. To the best of our knowledge, MP-SO₃H is the first solid acid catalyst to exemplify highest activity for the synthesis of different alkyl methyl carbonates using DMC. The protocol developed herein opens up new avenues to transform wide range of bio-alcohols into useful organic carbonates in the future.

In this work, two spinels type catalysts families Ni_1-xMg_xAl₂O₄ (x = 0.01/0.05/0.1, NiMg_x) and Mg_1-xNi_xAl₂O₄ (x = 0.05/0.1/0.2, MgNi_x) were synthetized by the citrate method with the aim of generating Ni metal particles over a basic support. These catalysts were characterized by different techniques such as X-ray diffraction (XRD), specific surface area (S_BET), temperature programed reduction (TPR), temperature programed desorption of CO₂ (TPD-CO₂) and x-ray photoelectron spectroscopy (XPS). The synthesis method was appropriate, since pure structures were obtained with a suitable surface area. NiMg_x catalysts presented the highest surface area values, about the double of MgNi_x. These catalysts also showed a higher reducibility with maxima around 800 ºC, which was 200 ºC less than those of MgNi_x and, therefore, the higher Ni⁰ content at the surface. TPD-CO₂ results evidenced that basicity of samples increased with the increase in Mg content. The presence of basic strong sites was observed for MgNi_x while NiMg_x only presented weak and medium basic sites. These results showed that NiMgx catalysts could be easily used in reactions where medium basic sites are needed.

Tetra Methyl Ammonium Hydroxide as well as Tetra n-Butyl Ammonium Hydroxides represent a feasible alternative to inorganic alkalis for hydrotalcites synthesis. For the most part, the washing step in the synthesis of hydrotalcites by inorganic alkalis generates a large amount of wastewater that must be processed afterwards generating high costs and environmental problems. The organic alkalis conduct the system towards smaller amounts of wastewater (<250 mL for 20 g of dried hydrotalcites synthesis). Therefore, the energy involved in the subsequent purifications of wastewater decreases significantly. This notable lower consumption of washing water and energy offsets against the slightly increased price of these organic alkalis. Moreover, both preparation methods, i.e. co-precipitation and mechano-chemical, generate pure LDH structures. The crystallinity of hydrotalcite synthesized with TMAH is more pronounced than that obtained with TBAH. A crucial property for these materials, i.e. memory effect, is also present. The trend of catalytic activities in the cyanoethylation reaction of ethanol with acrylonitrile, regardless of the preparation method, follows the trend: mixed oxides (≈ 80%) > reconstructed samples > dried samples. This tendency is in line with the strength of the base sites involved. However, all investigated solids generate 100% in the selectivity to 3-ethoxypropionitrile.

Traditionally, the synthesis of LDH-type materials is performed by the co-precipitation method and inorganic alkalis presence. However, Tetra Methyl Ammonium Hydroxide seems to be a viable alternative for the synthesis of these materials. Mg_0.75Al_0.125Y_0.125 LDH-type materials were prepared by two methods, co-precipitation and mechano-chemical, in the presence of TMAH. The corresponding mixed oxides were obtained by calcination at 460 °C in air. The memory effect was used in order to reconstruct the LDH layered structure. The samples were characterized by XRD, DRIFT, basicity by irreversible adsorption organic molecules with different pK_a, DTA-TG, N₂ adsorption - desorption isotherms. XRD patterns confirm the obtaining of LDH structure with some Y(OH)₃ impurities while mixed oxides illustrates the forming of an MgO-periclase like solid solution with Y₂O₃ which remains stable in the reconstructed structure. The catalytic activity of samples was determined in the aldol condensation reaction between benzaldehyde and cyclohexanone. The sample c-LDH-MgAlY-TMAH-MC presents 56% cyclohexanone conversion after 2h at 120°C. The activities keep the trend: mixed oxides > reconstructed > dried samples, regardless of the preparation method used. This variation linearly depends on the total basicity of the samples. Also, the selectivity towards to the di-condensate product, namely 2,6-dibenzylidene-cyclohexanone, is more than 99%.

Different countries in Europe has proposed different restrictions about bisphenol A (BPA), considered an endocrine disruptor, for the production of food packing and toys for children, for example; Denmark, France, Sweden, Belgium, Austria and Norway. However, it has been still found in wastewater effluents. In this study, BPA was degraded by catalytic wet air oxidation employing ruthenium-impregnated carbon nanosphere catalysts (CNS). The catalyst was synthetized with a mixture of resorcinol and formaldehyde and later a pyrolysis treatment it was impregnated by 1, 2, 5, 7 and 10% of ruthenium and activated with hydrogen at 350ºC. The experimental installation was a batch Hastelloy high-pressure reactor of 100 mL of volume with an electrical jacket and a variable speed magnetic drive. The concentration of BPA was followed by high performance liquid chromatography. After the study of different experiment variables (temperature (110-160ºC), pressure (20-50 bar), initial concentration of BPA (5-30 mg·L^-1) and catalyst mass (50-300 mg)) in a batch reactor of 100 mL of capacity two different potential models (r=k·(CBPA)^a and r=k·(C_BPA)^a·P^b·CRu^c) were used for simulating the kinetic behavior of BPA from the adjustment of the experimental data obtained for CWAO reactions. It was also tested different loads of ruthenium (1-10%) in the degradation of BPA. The both adjustments had a correlation factor of 0.98 and reproduced well all the experiments, being better those ones with 20 mg·L^-1 of initial concentration of BPA. The degradation of BPA was above 97% at 90 minutes of reaction time from 2% of Ru in the catalyst.

Most plastics degradation methods are currently inefficient and are limited by processing difficulties, quality loss and diminished value. This research focuses on the development of novel mechano-chemical disintegration processes for the breakdown of waste plastics. The outputs will be biocatalysed and used as building blocks for new polymers or other bioproducts. For the purpose of this research, microwave pre-treatment technology was used. Microwave technology is an ideal pre-treatment process for degradation of plastics due to its lower treatment times under lower energy inputs. In the previous work, extensive research has been carried out utilizing different solvents and catalysts to develop efficient degradation mechanism under microwave irradiations. A new class of ionic liquids (deep eutectic solvents) was used as catalysts to make suspension with Poly(ethylene terephthalate)PET and develop alcoholysis reaction. Certain degradation parameters like crystallinity index, weight loss, carbonyl index were depicted using DSC, TGA and FTIR characterisation techniques. Furthermore, enhanced enzymatic degradation proved that microwave technology is an efficient process for the alcoholysis reactions and degradation of PET under mild conditions.

Direct conversion of CO₂ into chemical compounds has become a prospective pathway to transform CO₂ into valuable chemical compounds. Introduction of porous materials with high CO₂ uptake into the photocatalytic system can enrich the CO₂ absorption on the surface of the photocatalyst for catalytic conversion. In this regard, another feasible strategy can be accomplished via combining commercial photocatalyst material into porous supporting materials. The present study investigated a series of ZnO-incorporated ZSM-5 catalysts to produce solar fuels under UV/Visible light irradiation. ZnO/ZSM-5 was synthesized using wet-impregnation method using Zn(CH₃COO)₂ as reagent and followed by calcination. Various characterizations were also conducted to study the morphology, structure, absorbance, and physiochemical properties of the photocatalyst. SEM-EDX images showed that ZnO was successfully incorporated into ZSM-5 surfaces with particle size around 50 nm. Optical properties of the ZnO/ZSM-5 correspond to 3.00 eV, showing a significant decrease of the bandgap value than pure ZnO, which corresponds to 3.10 eV. The solar fuels generation for H₂ and hydrocarbons, such as HCOH, CH₃OH, and HCOOH evolution reaction were evaluated in the photocatalytic CO₂ reduction under UV/Visible light irradiation. Incorporating the ZnO heterostructure in the ZSM-5 surface resulted in more efficient charge transfer, improved light absorption, and more active sites available for the CO₂ adsorption and photocatalytic reactions. The ZnO/ZSM-5 composite exhibited a remarkably high H₂ and CH₃OH evolution after 2 h of irradiation. A mechanism of the photocatalytic reaction was proposed.