Cumulative reported evidence has indicated that renewable feedstocks are a promising alternative source to fossil platforms for the production of fuels and chemicals. In that regard, the development of new, highly active, selective, and easy to recover and reuse catalysts for biomass conversions is urgently needed. The combination of enzymatic and inorganic heterogeneous catalysis generates an unprecedented platform that combines the advantages of both, the catalytic efficiency and selectivity of enzymes with the ordered structure, high porosity, mechanical, thermal, and chemical resistance of mesoporous materials to obtain enzymatic heterogeneous catalysts. Enzymatic mineralization with an organic silicon precursor (biosilicification) is a promising and emerging approach for the generation of solid hybrid biocatalysts with exceptional stability under severe use conditions. Herein, we assessed the putative advantages of the biosilicification technology for developing an improved efficient, and stable biocatalyst for sustainable biofuel production. A series of solid enzymatic catalysts denominated LOBE (low ordered biosilicified enzyme) were synthesized from Pseudomonas fluorescens lipase and tetraethyl orthosilicate. The microscopic structure and physicochemical properties characterization revealed that the enzyme formed aggregates that were contained in the heart of silicon- covered micelles, providing active sites with the ability to process different raw materials (commercial sunflower and soybean oils, Jatropha excisa oil, waste frying oil, acid oil from soybean soapstock, and pork fat) to produce first- and second-generation biodiesel. Ester content ranged from 81 to 93% wt depending on the raw material used for biodiesel synthesis. A heterogeneous enzymatic biocatalyst, LOBE4, for efficient biodiesel production was successfully developed in a single-step synthesis reaction using biosilicification technology. LOBE4 showed to be highly efficient in converting refined, non-edible, and residual oils (with high water and free fatty acid contents) and ethanol into biodiesel. Thus, LOBE4 emerges as a promising tool to produce second-generation biofuels, with significant implications for establishing a circular economy and reducing the carbon footprint.

Investigations at low and high pressure deliver information about the ways of CO hydrogenation and reasons for product distribution on Co+Pd catalysts. Properties of (Co+Pd)/TiO2(Al2O3) systems prepared in H2 were studied. Data obtained at 1 atm showed CoPdT samples as more active but CoPdA had higher CH4 selectivity. Metal dispersion was 1-3%. Bimodal particle distribution discerns CoPdA showing trend to agglomeration and alloying. CO adsorption proceeded on highly varied sites. CoPdA demonstrated high temperature H2 desorption, increased H/CO ratio on the surface, CO species firmly detained on the surface; stable carbonates. CoPdT appeared SMSI even after contact with H2O and air. Reaction was accompanied by surface reconstruction and increased formation of CH2 group increasing Treac. Both systems had potential to produce higher hydrocarbons even at 1 atm. Catalyst performance at 10.2 atm revealed dependence on Tred. CO conversion decreased with time and in comparison with selectivity at 1 atm synthesis of C2+ hydrocarbons increased but CO2 amount decreased. CH4/CO2 ratio was higher for CoPdA. CO conversion decrease was due to difficult reagents/intermediates/products diffusion and particles agglomeration. Higher Tred favoured decrease in CO2 production by WGSR, particles agglomeration and alloy formation.

Natural Deep Eutectic Solvents (NADESs) represent a new generation of biocompatible solvents, formed by eutectic mixtures of two or more hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) compounds of natural origin, with a lower melting point compared to that of pure components.¹ This feature is due to the strong ability of association between the components of the mixture through hydrogen bonds, that leads to a supramolecular assembly, configured as a new entity with peculiar properties. The ease of preparation, sustainability, low cost and nontoxicity of NADESs have allowed these solvents to be investigated in many applications. Recently, good results have been obtained with NADES as solvents in biocatalytic reactions, where they can improve substrate supply, conversion, and enzymatic stability.²

In this communication we describe the enzymatic activity of two oxidoreductases, the Horse Liver Alcohol Dehydrogenase (HLADH) and the Enoate Reductase from Thermus scotoductus (TsER) in buffer solution and in mixtures choline-based NADES/buffer. In particular, we have studied the lactonization of 3-methyl-1,5-pentanediol into 4-methyl-δ-valerolactone and the ketoisophorone bioreduction into levodione, evaluating the reaction rate, enantioselectivity and stability of the two enzymes. The stability of the nicotinamide cofactors NADH and NADPH was also evaluated.

1. Liu, Y.; Friesen, J. B.; McAlpine, J. B.; Lankin, D. C.; Chen, S.-N.; Pauli, G. F. Natural Deep Eutectic Solvents: Properties, applications, and perspectives. Nat. Prod. 2018, 81, 679-690.
2. Pätzold, M.; Siebenhaller, S.; Kara, S.; Liese, A.; Syldatk, C.; Holtmann, D. Deep Eutectic Solvents as efficient solvents in biocatalysis. Trends Biotechnol. 2019, 37, 943-959.

The development of efficient and sustainable strategies that evades the utilization of petroleum reserves is highly challenging yet inevitable today. In this regard, the conversion of pine tree-derived β-pinene to highly recognized nopol is particularly attractive owing to its widespread applications. Herein, we describe an approach that enables the selective synthesis of nopol with extraordinarily activity of MIL-101(Cr). This remarkable activity of MIL-101(Cr) attributed to its high specific surface area (SSA), accessible active sites in the mesopore architecture and unsaturated Cr³⁺ Lewis acid sites. We have established a good correlation between the superior catalytic performance and textural properties of the materials, which can be tuned by using different mineralizing agents. To realise the unprecedented catalytic activity, the influence of reaction parameters, solvent properties, and mineralizing agents have been investigated systematically. The MIL-101(AA) (AA-Acetic acid) exemplified the highest catalytic activity, which is superior to most of the reported materials for this transformation to date. The results of catalyst recycle and hot filtration experiments have emphasized that the catalyst is resistant towards leaching of active sites and retained its original catalytic activity beyond four recycles. This approach opens up new avenues for the valorization of biomass-based molecules into useful chemicals.

Malic acid represents a chemical platform to oxaloacetic acid (OAA) and pyruvic acid (PA) synthesis, which in turn are raw materials for essential aminoacids synthesis. The use of malic acid is a viable alternative because has the great potential to be produced from biomass.
1. Objectives
L-Malic acid, easily accessible from natural sources such as berries, apple and grape, represents an important biomass derived compound, used as precursor to essential aminoacids and biopolymers synthesis. Its transformation in other added values chemical such as OAA and PA is of interest for the scientific community, therefore to find the proper catalyst to do this transformation represents an important challenge.
Among different materials, iron-cobalt based mixed oxides are very interesting ones with high stability, magnetic properties and furthermore, are environmentally friendly and inexpensive compounds. They are used in many fields and especially in organics degradation, as materials for energy storage, for water electrocatalytic oxidation and for water photo-reduction1.
Our objective was to prepare iron-cobalt mixed oxides, to investigate their morphological and structural properties as well as their catalytic properties in malic acid oxidative dehydrogenation.
2. Results and discussion
Samples with different ratio between Co and Fe (0, 0.02, 0.03, 0.05), named Co0Fe, Co1Fe, Co2Fe and Co3Fe respectively, were synthesized by coprecipitation of cobalt and iron precursors with ammonium carbonate.
XRD patterns (Fig. 1) of synthesized samples present diffraction lines pertaining to α-Fe2O3 rhombohedral hematite structure. No lines corresponding to cobalt oxides were identified, meaning that the Co atoms are part of the hematite structure, they replacing the Fe atoms from the lattice.
The FTIR spectrum (Fig. 2) of Co0Fe sample presents a broad band located at 3450 cm-1 assigned to stretching vibration of water molecules physisorbed on the surface. This band almost disappears in the samples with cobalt, indicating that cobalt presence in the material reduces the adsorption of water on the surface.
The prepared catalysts were tested in malic acid oxidative dehydrogenation reaction. The solvents used were water and ethanol. The main products identified by gas-chromatography were oxaloacetic acid, pyruvic acid and esters of malic acid. It was observed that, oxaloacetic acid yield depends on the reaction temperature and time, being favored by low temperatures and short reaction times.
The FTIR spectra recorded for the tested samples provide clear evidence of oxaloacetic acid adsorption on the surface, characterized by the bands located in the 1220-1320 cm-1 region. Also, the pyruvic acid production is evidenced through the presence of bands located in the 1700-1800 cm-1 region, while unreacted malic acid is evidenced by the presence of bands in the 2850-3000 cm-1 region.

Figure 1. XRD patterns of iron-cobalt oxides

Figure 2. FTIR spectra of Co-Fe oxides,
before (a) and after (b) catalytic reaction

Conclusions
Iron-cobalt mixed oxides catalyze malic acid oxidative dehydrogenation with O2 using water or ethanol as solvent, at low temperature (25-70°C). The most favorable conditions for oxaloacetic acid production are low temperatures and short reaction times.

References
1. N. Helaili, G. Mitran, I. Popescu, K. Bachari, I.C. Marcu, A. Boudjemaa, J. Electroanalytical Chem. 742, 2015, 47–53

Acknowledgements:
This work was supported by a grant from the Romanian Ministry of Education and Research, CNCS–UEFISCDI, project number PNIII-P4-ID-PCE-2020-0580, within PNCDI III.

Contact information:
geta.mitran@chimie.unibuc.ro; florentina.neatu@infim.ro

The use of antibiotics has been growing and, consequently, their unregulated disposal has become a global concern for the pollution of water bodies. The development of technologies and materials to remove these contaminants is a relevant topic, so photocatalysis appears as an efficient method for removing these pollutants, termed emerging contaminants, mainly due to its ability to mineralize the target molecules. Clay minerals are used as supports for semiconductors in order to increase the photocatalytic activity in the degradation of various pollutants. In this sense, the objective of this research is to develop new photocatalysts by incorporating Ag and ZnO nanoparticles in synthetic saponite to be used in the photodegradation of the antibiotic ciprofloxacin in aqueous solution. The materials were synthesized by colloidal route. The results showed a good incorporation of nanoparticles on the support surface. The optical gap of the ZnO-saponite nanocomposite corresponds to 3.1 eV, whereas the Ag@ZnO-saponite nanocomposite (after deposition of Ag NPs) showed significant displacement variation in the band gap values, corresponding to 2.2 eV. This decrease justifies the photocatalytic activity in the visible region. The Ag@ZnO-saponite nanocomposite showed efficiency close to 90% of photodegradation of ciprofloxacin after 120 min of irradiation. Therefore, this material proves to be highly efficient for antibiotic degradation under visible light irradiation.

The development of active semiconductor photocatalysts with desirable material properties and efficient carrier transformation is indispensable for better photocatalyst utilization and performance optimization. Here, Salicylic acid-modified dysprosium doped TiO₂ (TNP-Dy/AS) complex materials were firstly synthesized via modified sol–gel followed by impregnation method.

The developed TNP- Dy material had a well-designed nanostructure, in which the TiO₂ nanoparticles (TNP) and Dy materials were closely bounded with each other. The salicylic acid complexes fixed on the TNP surface which were confirmed by TEM and SEM, thus improving the surface area and subsequently charge separation. Innovatively merged photocatalysts of salicylic acid (AS) complexes with TNP-Dy were successfully verified for photocatalytic degradation of organic contaminant (2,4 DCP) under the visible light degradation.

As compared to original TNP-Dy, TNP-Dy/AS showed prominent improvement in the catalytic actions. Kinetics i.e., K _app, and R ₂ (linear regression co-efficient) were also studied. The amended materials created charge separation, by means of electrons gathering at the higher CB, and holes gathering at the lower level valence band of the complex, therefore improving mineralization efficiency of the electrons and holes.

To be effective in photocatalysis application, the TiO₂ complexes should be stable during photocatalysis and does not undergo self-degradation. The TNP-Dy/AS and TNP/SA samples were irradiated 120 min and 240 min in water, separated and then dried without any heat treatment. After irradiation time (120 min), SA bands decrease slightly in intensity, while the ( –COOTi–) band centered at 1386 cm^-1 has shifted gradually, ultimately reaching 1360 cm^-1 with a shoulder at 1395 cm^-1.The results confirms that the coordination in TNP-Dy/AS is stronger compared to TNP/SA , leading to excellent chemical stability.

Directed thermo-mechano-chemical-irradiative methodologies which can permeate the significant plastic chemical resistance are central to achieving circularity in the life cycles of plastics. Here a novel combined deep eutectic solvent (DES) microwave irradiation technique for fast, high efficiency, high yield polyethylene terephthalate (PET) hydrolytic depolymerization with high amenability for sustainable industrial scalability is presented. In this work, depolymerization of PET was performed using a dissolution/degradation approach. A dual functioning DES served as the solubilizing and catalysing agent for PET alkaline hydrolysis. Microwave (MW) irradiation was utilized for facilitating the depolymerization process with high energy efficiency. The PET depolymerization process was optimized using box behnken design while studying the volume of DES, concentration of depolymerizing agent and MW irradiation time as independent variables. A percentage weight loss of PET reaching 84% was obtained in 90 seconds of MW irradiation. Various characterization techniques such as FTIR, DSC and HPLC validated the depolymerization of PET and obtained monomers (mainly terephthalic acid (TPA)). Finally, a postconsumer PET sample was also evaluated to prove that the developed dissolution/degradation approach could have practical application in market. Post analysis, the insoluble matter content was calculated to be 3.70% and the yield of pure TPA was 95.54%.

The reverse water gas shift (RWGS) reaction is a potential method for converting CO₂ into CO, which can subsequently be employed as a syngas component to make useful chemicals and liquid fuels. The reaction is mildly endothermic and at low temperatures, it competes with an extremely exothermic CO₂ methanation reaction. As a result, designing highly selective catalysts for the RWGS reaction, leading to cost-effective CO₂ hydrogenation, remains an important and difficult challenge. In this study, Cu-based materials were investigated for their ability to convert carbon dioxide into syngas utilizing ceria as a support. Ceria is known to be a good catalyst as well as an excellent support for oxygen and hydrogen transfer reactions (hydrogenation and dehydrogenation). Our experimental results showed that increasing the temperature enhances CO₂ conversion, with the highest conversion of 70% at 600°C that remained stable for over 1000 minutes time on stream (TOS) runs. The other point to note is that the catalyst was CO-selective, with no CH₄ detected in the effluent gas. Furthermore, both fresh and post-reaction samples were analyzed using different techniques such as XRD, TEM, SEM/EDX, and Raman to explore the crystallographic and morphological features of the support and catalyst as well as the influence of reaction on the catalyst surface. The findings may provide an effective platform for minimizing precious metals application as catalysts for CO₂ conversion reactions.

Cu(x)MgFeO mixed oxides(with Mg/Fe = 3 and 2.5 ≤ x ≤ 20 at. %) were obtained from layered double hydroxides (LDH) precursors, characterized and tested in the hydrodeoxygenation reaction of benzyl alcohol. The LDH precursors were prepared through coprecipitation, then dried and calcined at 500 ⁰C. The solids were characterized by XRD, N₂ adsorption-desorption, H₂-TPR, CO₂-TPD and SEM-EDX techniques. Catalytic tests were performed in an autoclave reactor under 5 atm of H₂. The influence of Cu loading (2.5 – 20 at. % with respect to cations), reaction temperature (150 – 230 °C), and reaction time (15 min – 5 h) were investigated.

XRD patterns of the precursors showed typical reflections for the LDH structure, with no segregated phases, except for the sample with 20 % Cu. The mixed oxides showed, besides the periclase phase, the presence of MgFe₂O₄. The sample with 20 % Cu also showed diffraction lines for CuO. All mixed oxides presented high specific surface areas and mesoporous structures. High hydrogen consumptions, corresponding to the reduction of both Fe and Cu species, were observed in H₂-TPR measurements, while CO₂-TPD confirmed the presence of low and medium-strength basic sites.

With 94 % alcohol conversion and 94 % selectivity for toluene, Cu(10)MgFeO was the best catalyst in this series. The influence of reaction temperature and reaction time were also studied. Catalytic tests using benzaldehyde and benzyl benzoate as reactants confirmed them as reaction intermediates. The catalytic performances of the Cu(x)MgFeO catalysts were correlated with the basicity and reducibility results.