Search Results (62)

To enhance the performance of photocatalytic CO₂ reduction, the development of suitable cocatalysts represents an effective strategy. Cocatalysts can interact with photocatalysts to improve light absorption capabilities and facilitate the separation and transfer of photogenerated electrons and holes. Moreover, they provide highly active surface sites that promote the adsorption and activation of CO₂, which leads to acceleration of photocatalytic reduction. Herein, WO₃ is employed as a cocatalyst to promote the CO₂ photoreduction performance of a g-C₃N₄-TiO₂ heterojunction through a facile and scalable calcination method. In pure water, optimal WO₃/g-C₃N₄-TiO₂ (WCT) delivers high selectivity CO and CH₄ formation of 48.31 µmol·g⁻¹ and 77.18 µmol·g⁻¹ in the absence of a sacrificial reagent and extra photosensitizer, roughly 13.9 and 45.7 times higher than that of g-C₃N₄-TiO₂ (CT). WO₃ can strongly interact with g-C₃N₄-TiO₂ electronically, guiding electrons across the interface to the surface. The oxygen vacancies in WO₃, as electron-enriched centers, not only enhance charge separation and form efficient charge transfer channels but also capture photogenerated electrons to suppress charge recombination. This strong interaction and oxygen vacancies in WO₃ jointly improve photocatalytic CO₂ reduction activity and selectivity, offering a feasible way to design efficient cocatalysts. Full article

An Integrated Process Intensification (IPI) technology-based roadmap is proposed for the utilization of renewables (water, air and biomass/unavoidable waste) in the small-scale distributed production of the following primary products: electricity, H₂, NH₃, HNO₃ and symbiotic advanced (SX) fertilizers with CO₂ mineralization capacity to achieve negative CO₂ emission. Such a production platform is an integrated intensified biorefinery (IIBR), used as an alternative to large-scale centralized production which relies on green electricity and CCUS. Hence, the capacity and availability of the renewable biomass and unavoidable waste were examined. The critical elements of the IIBR include gasification/syngas production; syngas cleaning; electricity generation; and the conversion of clean syngas (which contains H₂, CO, CH₄, CO₂ and N₂) to the primary products using nonthermal plasma catalytic reactors with in situ NH₃ sequestration for SA fertilizers. The status of these critical elements is critically reviewed with regard to their techno-economics and suitability for industrial applications. Using novel gasifiers powered by a combination of CO₂, H₂O and O₂-enhanced air as the oxidant, it is possible to obtain syngas with high H₂ concentration suitable for NH₃ synthesis. Gasifier performances for syngas generation and cleaning, electricity production and emissions are evaluated and compared with gasifiers at 50 kWe and 1–2 MWe scales. The catalyst and plasma catalytic reactor systems for NH₃ production with or without in situ reactive sequestration are considered in detail. The performance of the catalysts in different plasma reactions is widely different. The high intensity power (HIP) processing of perovskite (barium titanate) and unary/binary spinel oxide catalysts (or their combination) performs best in several syntheses, including NH₃ production, NO_x from air and fertigation fertilizers from plasma-activated water. These catalysts can be represented as BaTi_1−vO_3−x{#}_yN_z (black, piezoelectric barium titanate, bp-{BTO}) and M⁽¹⁾_3−jM⁽²⁾_kO_4−m{#}_nN_r/SiO₂ (unary (k = 0) or a binary (k > 0) silane-coated SiO₂-supported spinel oxide catalyst, denoted as M/Si = X) where {#} infers oxygen vacancy. HIP processing in air causes oxygen vacancies, nitrogen substitution, the acquisition of piezoelectric state and porosity and chemical/morphological heterogeneity, all of which make the catalysts highly active. Their morphological evaluation indicates the generation of dust particles (leading to porogenesis), 2D-nano/micro plates and structured ribbons, leading to quantum effects under plasma catalytic synthesis, including the acquisition of high-energy particles from the plasma space to prevent product dissociation as a result of electron impact. M/Si = X (X > 1/2) and bp-{BTO} catalysts generate plasma under microwave irradiation (including pulsed microwave) and hence can be used in a packed bed mode in microwave plasma reactors with plasma on and within the pores of the catalyst. Such reactors are suitable for electric-powered small-scale industrial operations. When combined with the in situ reactive separation of NH₃ in the so-called Multi-Reaction Zone Reactor using NH₃ sequestration agents to create SA fertilizers, the techno-economics of the plasma catalytic synthesis of fertilizers become favorable due to the elimination of product separation costs and the quality of the SA fertilizers which act as an artificial root system. The SA fertilizers provide soil fertility, biodiversity, high yield, efficient water and nutrient use and carbon sequestration through mineralization. They can prevent environmental damage and help plants and crops to adapt to the emerging harsh environmental and climate conditions through the formation of artificial rhizosphere and rhizosheath. The functions of the SA fertilizers should be taken into account when comparing the techno-economics of SA fertilizers with current fertilizers. Full article

Converting carbon dioxide (CO₂) into solar fuels through photocatalysis represents an appealing approach to tackling the escalating energy crisis and mitigating the greenhouse effect. In this study, using melamine–formaldehyde (MF) nanospheres as a nitrogen source, a N element was simultaneously doped into the TiO₂ nanoparticle structure supported by carbon hollow spheres using a one-step carbonization method to form a heterojunction N-CHS@N-TiO₂ (marked as (N-(CHS@TiO₂)). The composite showed superior photocatalytic activity in reducing CO₂ compared with TiO₂ and N-CHS: after 6 h of visible light irradiation, the CO yield was 4.3 times that of N-CHS and TiO₂; 6 h of UV irradiation later, the CO yield reached 2.6 times that of TiO₂ and 7 times that of N-CHS. The substantial enhancement in photocatalytic activity was attributed to the nitrogen simultaneously doped carbon hollow spheres and TiO₂, mesoporous structure, small average TiO₂ crystal size, large surface areas, and the heterostructure formed by N-CHS and N-TiO₂. The UV-vis diffuse reflectance spectra (DRS) exhibit a significant improvement in light absorption, attributed to the visible-light-active carbon hollow sphere and the N element doping, thereby enhancing solar energy utilization. Full article

Thiosemicarbazones (TSCs) with their modular character (thiosemicarbazides + carbonyl compound) allow broad variation of up to four substituents on the main R¹R²C=N(1)–NH–C(S)–N(4)R³R⁴ core and are thus interesting tools for the formation of conjugates or the functionalization of nanoparticles (NPs). In this work, di-2-pyridyl ketone was introduced for the coordination of metals and 9-anthraldehyde for luminescence as R¹ and R² to TSCs. R³ and R⁴ substituents were varied for the formation of conjugates. Amino acids were introduced at the N4 position to produce [R¹R²TSC–spacer–amino acid] conjugates. Further, functions such as phosphonic acid (R–P(O)(OH)₂), D-glucose, o-hydroquinone, OH, and thiol (SH) were introduced at the N4 position producing [R¹R²TSC–spacer–anchor group] conjugates for direct NP anchoring. Phenyl, cyclohexyl, benzyl, ethyl and methyl were used as spacer units. Both phenyl phosphonic acid TSC derivatives were bound on TiO₂ NPs as a first example of direct NP anchoring. [R¹R²TSC–spacer–end group] conjugates including OH, S–Bn (Bn = benzyl), NH–Boc (Boc = tert-butyloxycarbonyl), COOtBu, C≡CH, or N₃ end groups were synthesized for potential covalent binding to functional molecules or functionalized NPs through amide, ester, or triazole functions. The synthesis of the thiosemicarbazides H₂NNH–C(S)–NR₃R₄ starting from amines, including amino acids, SCCl₂ or CS₂, and hydrazine and their condensation with dipyridyl ketone and anthraldehyde led to 34 new TSC derivatives. They were synthesized in up to six steps with overall yields ranging from 10 to 85% and were characterized by a combination of nuclear magnetic resonance spectroscopy and mass spectrometry. UV-vis absorption and photoluminescence spectroscopy allowed us to easily trace the dipyridyl imine and anthracene chromophores. Full article

Mineralogy and formation conditions were studied in a newly found vein wolframite mineralization, cutting migmatitized paragneisses in the exocontact of a small Carboniferous granite body in the Pohled quarry, Moldanubian Zone of the Bohemian Massif, Czech Republic. The early stage of the rich mineral assemblage (36 mineral species) involves wolframite, columbite-group minerals, molybdenite, and scheelite hosted by quartz–muscovite–chlorite gangue, which was followed by base-metal sulfides in a quartz gangue, whereas the last stage included calcite gangue with fluorite and minor sulfides. The mineral assemblage points to the mobility of usually hardly soluble elements, including W, Sn, Zr, Nb, Th, Ti, Sc, Y, and REEs. A fluid inclusion study indicates a significant decrease in homogenization temperatures from 350–370 °C to less than 100 °C during vein formation. Fluids were aqueous, with a low salinity (0–12 wt. % NaCl eq.) and traces of CO₂, N₂, CH₄, H₂, and C₂H₆. The δ¹⁸O values of the fluids giving rise to quartz and scheelite are positive (min. 4‰–6‰ V-SMOW). The Eh and pH of the fluid also changed during evolution of the vein. Both wolframite and columbite-group minerals are anomalously enriched in Mg. We suggest that the origin of this distinct mineralization was related to the mixing of Mo,W-bearing granite-derived magmatic fluids with external basinal waters derived from contemporaneous freshwater (but episodically evaporated) piedmont basins. The basinal waters infiltrated into the subsurface along fractures formed in the extensional tectonic regime, and their circulation continued even after the ending of the activity of magmatic fluids. The studied wolframite mineralization represents the most complete record of the ‘hydrothermal’ history of a site adjacent to a cooling granite body in the study area. Moreover, there are broad similarities in the mineral assemblages, textures, and chemical compositions of individual minerals from other occurrences of wolframite mineralization around the Central Moldanubian Plutonic Complex, pointing to the genetic similarities of the Variscan wolframite-bearing veins in this area. Full article

This study examines the use of SrAl₂O₄: Eu²⁺, Dy³⁺ long-afterglow materials doped into g-C₃N₄/TiO₂ coatings for photodegradation. The prepared sample was tested for the purification of automotive exhaust fumes, with the optimal mass ratio of g-C₃N₄/TiO₂ and SrAl₂O₄: Eu²⁺, Dy³⁺ determined to be 1:1. Characterization tests, including XRD, FT-IR, XPS, and TG-DSC, were conducted to evaluate the microstructure and properties of the samples. Under poor lighting conditions, g-C₃N₄/TiO₂ reduced CH and NO_x by 59 ppm and 13 ppm within 4 h, respectively, while g-C₃N₄/TiO₂/SrAl₂O₄: Eu²⁺, Dy³⁺ decreased CH and NO_x by 98ppm and 34ppm, respectively, resulting in a significant improvement in degradation efficiency. The addition of long-afterglow materials significantly improves the efficiency of photocatalysts in purifying exhaust fumes in low-light environments, providing potential value for all-weather exhaust treatment in the future. Full article

Excessive emissions of carbon dioxide have led to the greenhouse effect and global warming. Reducing carbon dioxide into high-value-added chemicals through solar energy is a promising approach. Herein, a g-C₃N₄/TiO₂ heterojunction photocatalyst with efficient electron transfer is designed for photocatalytic CO₂ reduction. The CH₄ (18.32 µmol·h⁻¹·g⁻¹) and CO (25.35 µmol·h⁻¹·g⁻¹) evolution rates of g-C₃N₄/TiO₂ are higher than those of g-C₃N₄ and TiO₂. The enhanced photocatalytic CO₂ reduction performance is attributed to the efficient charge carrier transfer in the g-C₃N₄/TiO₂ heterojunction. The electron transfer route was verified by in situ irradiated X-ray photoelectron spectroscopy (XPS). The photocatalytic CO₂ reduction mechanism on g-C₃N₄/TiO₂ was investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). This work provides a strategy for designing a polymer/metallic oxide heterojunction with efficient electron transfer for enhanced photocatalytic CO₂ reduction. Full article

Printed circuit boards (PCBs) are the main components of e-waste. In order to reduce the negative impact of waste PCBs on human health and the environment, they must be properly disposed of. A new method is demonstrated for recycling waste PCBs. It is referred to as the high-temperature thermo-mechano-chemical gasification (TMCG) of PCBs by the detonation-born gasification agent (GA), which is a blend of H₂O and CO₂ heated to a temperature above 2000 °C. The GA is produced in a pulsed detonation gun (PDG) operating on a near-stoichiometric methane–oxygen mixture. The PDG operates in a pulsed mode producing pulsed supersonic jets of GA and pulsed shock waves possessing a huge destructive power. When the PDG is attached to a compact flow reactor filled with waste PCBs, the PCBs are subject to the intense thermo-mechano-chemical action of both strong shock waves and high-temperature supersonic jets of GA in powerful vortical structures established in the flow reactor. The shock waves grind waste PCBs into fine particles, which undergo repeated involvement and gasification in the high-temperature vortical structures of the GA. Demonstration experiments show full (above 98%) gasification of the 1 kg batch of organic matter in a setup operation time of less than 350 s. The gaseous products of PCB gasification are mainly composed of CO₂, CO, H₂, N₂, and CH₄, with the share of flammable gas components reaching about 45 vol%. The solid residues appear in the form of fine powder with visible metal inclusions of different sizes. All particles in the powder freed from the visible metal inclusions possess a size less than 300–400 μm, including a large fraction of sizes less than 100 μm. The powder contains Sn, Pb, Cu, Ni, Fe, In, Cd, Zn, Ca, Si, Al, Ti, Ni, and Cl. Among these substances, Sn (10–20 wt%), Pb (5–10 wt%), and Cu (up to 1.5 wt%) are detected in the maximum amounts. In the powder submitted for analysis, precious elements Ag, Au, and Pt are not detected. Some solid mass (about 20 wt% of the processed PCBs) is removed from the flow reactor with the escaping gas and is partly (about 10 wt%) trapped by the cyclones in the exhaust cleaning system. Metal inclusions of all visible sizes accumulate only in the flow reactor and are not detected in powder samples extracted from the cyclones. The gasification degree of the solid residues extracted from the cyclones ranges from 76 to 91 wt%, i.e., they are gasified only partly. This problem will be eliminated in future work. Full article

Poly(1,4-butylene succinate) (PBS) is a promising sustainable and biodegradable synthetic polyester. In this study, we synthesized PBS-based copolyesters by incorporating 5–20 mol% of –O₂CC₆H₄CO₂– and –OCH₂CH₂O– units through the polycondensation of succinic acid (SA) with 1,4-butanediol (BD) and bis(2-hydroxyethyl) terephthalate (BHET). Two different catalysts, H₃PO₄ and the conventional catalyst (nBuO)₄Ti, were used comparatively in the synthesis process. The copolyesters produced using the former were treated with M(2-ethylhexanoate)₂ (M = Mg, Zn, Mn) to connect the chains through ionic interactions between M²⁺ ions and either –CH₂OP(O)(OH)O⁻ or (–CH₂O)₂P(O)O⁻ groups. By incorporating BHET units (i.e., –O₂CC₆H₄CO₂– and –OCH₂CH₂O–), the resulting copolyesters exhibited improved ductile properties with enhanced elongation at break, albeit with reduced tensile strength. The copolyesters prepared with H₃PO₄/M(2-ethylhexanoate)₂ displayed a less random distribution of –O₂CC₆H₄CO₂– and –OCH₂CH₂O– units, leading to a faster crystallization rate, higher T_m value, and higher yield strength compared to those prepared with (nBuO)₄Ti using the same amount of BHET. Furthermore, they displayed substantial shear-thinning behavior in their rheological properties due to the presence of long-chain branches of (–CH₂O)₃P=O units. Unfortunately, the copolyesters prepared with H₃PO₄/M(2-ethylhexanoate)₂, and hence containing M²⁺, –CH₂OP(O)(OH)O⁻, (–CH₂O)₂P(O)O⁻ groups, did not exhibit enhanced biodegradability under ambient soil conditions. Full article

Immobilized [Ir(COD)Cl]₂-Linker/TiO₂ catalysts with linkers containing Py, P(Ph)₂ and N(CH₃)₂ functional groups were prepared. The catalysts were tested via propene hydrogenation with parahydrogen in a temperature range from 40 °C to 120 °C which was monitored via NMR. The catalytic behavior of [Ir(COD)Cl]₂-Linker/TiO₂ is explained on the basis of quantitative and qualitative XPS data analysis performed for the catalysts before and after the reaction at 120 °C. It is shown that the temperature dependence of propene conversion and the enhancement of the NMR signal are explained via a combination of the stabilities of both the linker and immobilized [Ir(COD)Cl]₂ complex. It is demonstrated that the N(CH₃)₂-linker is the most stable at the surface of TiO₂ under used reaction conditions. As a result, only this sample shows a rise in the enhancement of the NMR signal in the 100–120 °C temperature range. Full article

This multi-disciplinary paper aims to provide a roadmap for the development of an integrated, process-intensified technology for the production of H₂, NH₃ and NH₃-based symbiotic/smart fertilizers (referred to as target products) from renewable feedstock with CO₂ sequestration and utilization while addressing environmental issues relating to the emerging Food, Energy and Water shortages as a result of global warming. The paper also discloses several novel processes, reactors and catalysts. In addition to the process intensification character of the processes used and reactors designed in this study, they also deliver novel or superior products so as to lower both capital and processing costs. The critical elements of the proposed technology in the sustainable production of the target products are examined under three-sections: (1) Materials: They include natural or synthetic porous water absorbents for NH₃ sequestration and symbiotic and smart fertilizers (S-fertilizers), synthesis of plasma interactive supported catalysts including supported piezoelectric catalysts, supported high-entropy catalysts, plasma generating-chemical looping and natural catalysts and catalysts based on quantum effects in plasma. Their performance in NH₃ synthesis and CO₂ conversion to CO as well as the direct conversion of syngas to NH₃ and NH₃—fertilizers are evaluated, and their mechanisms investigated. The plasma-generating chemical-looping catalysts (Catalysts, 2020, 10, 152; and 2016, 6, 80) were further modified to obtain a highly active piezoelectric catalyst with high levels of chemical and morphological heterogeneity. In particular, the mechanism of structure formation in the catalysts BaTi_1−rM_rO_3−x−y{#}_xN_z and M₃O_4−x−y{#}_xN_z/Si = X was studied. Here, z = 2y/3, {#} represents an oxygen vacancy and M is a transition metal catalyst. (2) Intensified processes: They include, multi-oxidant (air, oxygen, CO₂ and water) fueled catalytic biomass/waste gasification for the generation of hydrogen-enriched syngas (H₂, CO, CO₂, CH₄, N₂); plasma enhanced syngas cleaning with ca. 99% tar removal; direct syngas-to-NH₃ based fertilizer conversion using catalytic plasma with CO₂ sequestration and microwave energized packed bed flow reactors with in situ reactive separation; CO₂ conversion to CO with BaTiO_3−x{#}_x or biochar to achieve in situ O₂ sequestration leading to higher CO₂ conversion, biochar upgrading for agricultural applications; NH₃ sequestration with CO₂ and urea synthesis. (3) Reactors: Several patented process-intensified novel reactors were described and utilized. They are all based on the Multi-Reaction Zone Reactor (M-RZR) concept and include, a multi-oxidant gasifier, syngas cleaning reactor, NH₃ and fertilizer production reactors with in situ NH₃ sequestration with mineral acids or CO₂. The approach adopted for the design of the critical reactors is to use the critical materials (including natural catalysts and soil additives) in order to enhance intensified H₂ and NH₃ production. Ultimately, they become an essential part of the S-fertilizer system, providing efficient fertilizer use and enhanced crop yield, especially under water and nutrient stress. These critical processes and reactors are based on a process intensification philosophy where critical materials are utilized in the acceleration of the reactions including NH₃ production and carbon dioxide reduction. When compared with the current NH₃ production technology (Haber–Bosch process), the proposed technology achieves higher ammonia conversion at much lower temperatures and atmospheric pressure while eliminating the costly NH₃ separation process through in situ reactive separation, which results in the production of S-fertilizers or H₂ or urea precursor (ammonium carbamate). As such, the cost of NH₃-based S-fertilizers can become competitive with small-scale distributed production platforms compared with the Haber–Bosch fertilizers. Full article

The work presented in this paper describes the preparation and the electrochemical application of functionalized chitosan-entrapped carbon paste electrodes (CH/CPE) for lead ions (Pb²⁺) detection in industrial wastewater. The chitosan was first functionalized using TiO₂ and CuO, which were both metal oxides that were obtained by extracting it from waste products derived from shrimp shells. The analytical performance of the as-prepared electrodes, CH/CPE, TiO₂-CH/CPE, and NiO-CH/CPE, for the detection of lead (II) was examined using electrochemical impedance spectroscopy (EIS) technique in the 0.1 M KNO₃ electrolyte solution. The effect of experimental conditions, including polarization potential, frequency, and pH, are optimized to maximize the sensitivity of the measurements. The developed impedimetric sensors provided a linear response over a concentration range of 10⁻⁶ to 10⁻⁴ M with a detection limit of 3.10⁻⁷ M based on S/N = 3. The DFT computational analysis demonstrated that chitosan biopolymer possesses the ability to adsorb Pb (II) ions that are present in wastewater. Chitosan and the derivatives of chitosan, have the potential to remove heavy metals from industrial effluent in a manner that is both economical and eco-friendly to the environment. Chitosan is a biopolymer that is abundantly renewable. Full article

This paper presents new photocatalysts obtained by treating carbon spheres (CS) and TiO₂ in a microwave reactor at a pressure of 20 atm and a temperature of up to 300 °C for 15 min and then depositing TiO₂/CS composites on glass fibre cloths. Such highly CO₂-adsorbing photocatalysts showed photoactivity in the simultaneous water-splitting process, generating H₂, reducing CO₂ to CO and CH₄, and reducing N₂ to NH₃. In addition, calculations of the hydrogen balance involved in all reactions were performed. Adding 1 g of carbon spheres per 1 g of TiO₂ maintained the high selectivity of nitrogen fixation at 95.87–99.5%, which was continuously removed from the gas phase into the water as NH₄⁺ ions. Full article

Blend membranes consisting of two polymer pairs improve gas separation, but compromise mechanical and thermal properties. To address this, incorporating titanium dioxide (TiO₂) nanoparticles has been suggested, to enhance interactions between polymer phases. Therefore, the objective of this study was to investigate the impact of TiO₂ as a filler on the thermal, surface mechanical, as well as gas separation properties of blend membranes. Blend polymeric membranes consisting of polyetherimide (PEI) and polyvinyl acetate (PVAc) with blend ratios of (99:1) and (98:2) were developed via a wet-phase inversion technique. In the latter, TiO₂ was incorporated in ratios of 1 and 2 wt.% while maintaining a blend ratio of (98:2). TGA and DSC analyses were used to examine thermal properties, and nano-indentation tests were carried out to ascertain surface mechanical characteristics. On the other hand, a gas permeation set-up was used to determine gas separation performance. TGA tests showed that blend membranes containing TiO₂ had better thermal characteristics. Indentation tests showed that TiO₂-containing membranes exhibited greater surface hardness compared to other membranes. The results of gas permeation experiments showed that TiO₂-containing membranes had better separation characteristics. PEI–PVAc blend membranes with 2 wt.% TiO₂ as filler displayed superior separation performance for both gas pairs (CO₂/CH₄ and CO₂/N₂). The compatibility between the rubbery and glassy phases of blend membranes was improved as a result of the inclusion of TiO₂, which further benefited their thermal, surface mechanical, and gas separation performances. Full article

Interaction of [VO(OiPr)₃] with 6-bis(o-hydroxyaryl)pyridine, 2,6-{HOC(Ph)₂CH₂}₂(NC₅H₃), LH₂, afforded [VO(OiPr)L] (1) in good yield. The reaction of LNa₂, generated in-situ from LH₂ and NaH, with [VCl₃(THF)₃] led to the isolation of [VL₂] (2) in which the pyridyl nitrogen atoms are cis; a regioisomer 3∙2THF, in which the pyridyl nitrogen atoms are trans, was isolated when using [VCl₂(TMEDA)₂]. The reaction of the 2,6-bis(o-hydroxyalkyl)pyridine {HOC(iPr)₂CH₂}₂(NC₅H₃), L¹H₂, with [VO(OR)₃] (R = nPr, iPr) led, following work-up, to [VO(OR)L¹] (R = nPr (4), iPr (5)). Use of the bis(methylpyridine)-substituted alcohol (tBu)C(OH)[CH₂(C₅H₃Me-5)]₂, L²H, with [VO(OR)₃] (R = Et, iPr) led to the isolation of [VO(μ-O)(L²)]₂ (6). Complexes 1 to 6 have been screened for their ability to act as pre-catalysts for the ring opening polymerization (ROP) of ε-caprolactone (ε-CL), δ-valerolactone (δ-VL), and rac-lactide (r-LA) and compared against the known catalyst [Ti(OiPr)₂L] (I). Complexes 1, 4–6 were also screened as catalysts for the polymerization of ethylene (in the presence of dimethylaluminium chloride/ethyltrichloroacetate). For the ROP of ε-CL, in toluene solution, conversions were low to moderate, affording low molecular weight products, whilst as melts, the systems were more active and afforded higher molecular weight polymers. For δ-VL, the systems run as melts afforded good conversions, but in the case of r-LA, all systems as melts exhibited low conversions (<10%) except for 6 (<54%) and I (<39%). In the case of ethylene polymerization, the highest activity (8600 Kg·mol·V⁻¹bar⁻¹h⁻¹) was exhibited by 1 in dichloromethane, affording high molecular weight, linear polyethylene at 70 °C. In the case of 4 and 5, which contain the propyl-bearing chelates, the activities were somewhat lower (≤1500 Kg·mol·V⁻¹bar⁻¹h⁻¹), whilst 6 was found to be inactive. Full article