Synthesis and Characterization of Metal-Organic Polymer based on Fe(III)

In this work, a coordination polymer based on iron trinuclear acetate was synthesized. The coordination polymer was obtained in two stages. At the first stage [Fe3O(CH3CO2)6(H2O)3]·2H2O – tricyclic iron acetate was synthesized. As the dicarboxylate ligand, we chose muconic acid, which is not toxic to the body. Double bonds in its structure create additional nodes for interaction with drugs. The optimal conditions for the synthesis of a coordination polymer based on tricyclic iron acetate and muconic acid were selected: solvothermal synthesis at 78 °C, autogenous pressure and using ethanol as a solvent. The resulting coordination polymer is a nanosized mesoporous framework with a narrow pore distribution, an average radius of~1.18 nm, and a developed specific surface area of 512.1 m2/g. The composition and crystal structure of tricyclic iron acetate and a coordination polymer based on it have been confirmed by the methods of elemental and X-ray phase analysis.

Catalysis, Kinetic and Mechanistical Studies for the Transformation of Ethylene Glycol by Alumina and Silica Gel under Autogenous Pressure and Solvent-free Conditions

A kinetic and mechanistical studies of the new pathway for competitive transformation of ethylene glycol by alumina and silica gel have been described. Commercial alumina (Al com), synthetic alumina (Al syn), commercial silica gel (Si com) and synthetic silica gel (Si syn) were used for the transformation of ethylene glycol to a mixture of diethylene glycol, 1,4-dioxane and 2-methyl-1,3-dioxolane via acetaldehyde by heating at 150 °C under autogenous pressure without solvent. The results show that the yield of these three products strongly depends on the nature of the used catalyst and the reaction time.

Novel Sol-Gel Synthesis of Spherical Lead Titanate Submicrometer Powders

In this study, a novel and simple synthetic sol-gel procedure was established to directly prepare spherical lead titanate powders without prior synthesis/usage of spherical templates such as TiO2 particles. Isotropic submicron particles with a mean diameter of 1–4 μm were prepared in this way. This synthetic process takes advantage of acetone as a stabilizing ligand and autogenous pressure generated in the autoclave during the reaction. The influence of various experimental factors (nature of the ligand, thermal treatment mode, and post-calcining temperature) as well as the formation mechanism were studied. Scanning electron microscopy and transmission electron microscopy were used to explore the particle morphology. The crystalline phases were explored and identified by X-ray diffraction analysis.

Fabrication of MoS2-deposited TiO2 hollow microspheres and their enhanced photocatalytic application in the generation of hydrogen

Abstract MoS2-deposited TiO2 hollow spheres were synthesized successfully under mild temperature and autogenous pressure. The hydrothermal technique was adopted for the synthesis of the TiO2 hollow microsphere, followed by a photodeposition technique for the deposition of MoS2. The physical and chemical nature of the samples was characterized using X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, photoluminescence spectroscopy, XPS and UV–vis spectroscopy. In an aqueous medium under the influence of light, the characterized samples were used in the production of hydrogen via photocatalysis. The increase in the formation of hydrogen content during photocatalysis confirms the successful generation and the benefits of the photogenerated carriers. With an increase in the MoS2 content, there is an incredible change in the photocatalytic performance. The resultant is due to the free moment of the holes and electrons and lessening in charge recombination centres formed as a result of the nano-heterojunction linking between MoS2 and TiO2. A more significant photocatalytic production of hydrogen was achieved using 50 MST sample i.e. 106 μmol−1 g−1 beyond which it tends to decrease with an increase in MoS2 content. Graphic abstract

Kinetics of Alkyl Lactate Formation from the Alcoholysis of Poly(Lactic Acid)

Alkyl lactates are green solvents that are successfully employed in several industries such as pharmaceutical, food and agricultural. They are considered prospective renewable substitutes for petroleum-derived solvents and the opportunity exists to obtain these valuable chemicals from the chemical recycling of waste poly(lactic acid). Alkyl lactates (ethyl lactate, propyl lactate and butyl lactate) were obtained from the catalysed alcoholysis reaction of poly(lactic acid) with the corresponding linear alcohol. Reactions were catalysed by a Zn complex synthesised from an ethylenediamine Schiff base. The reactions were studied in the 50–130 °C range depending on the alcohol, at autogenous pressure. Arrhenius temperature-dependent parameters (activation energies and pre-exponential factors) were estimated for the formation of the lactates. The activation energies (Ea1, Ea2 and Ea−2) for alcoholysis in ethanol were 62.58, 55.61 and 54.11 kJ/mol, respectively. Alcoholysis proceeded fastest in ethanol in comparison to propanol and butanol and reasonable rates can be achieved in temperatures as low as 50 °C. This is a promising reaction that could be used to recycle end-of-life poly(lactic acid) and could help create a circular production economy.

Unique crystallization behavior in zeolite synthesis under external high pressures

Hydrothermal synthesis of zeolites under external high pressures generates unique crystallization behaviors that are different from the synthesis under autogenous pressure.

Indexing PXRD Structural Parameters of Graphene Oxide-Doped Metal-Organic Frameworks

A family of metal-organic framework, [Mg3O3(CO2)3]∞ nanocrystallites which are also known as Mg-MOF-74, were synthesized by solvothermal method at high temperature under autogenous pressure. The graphene oxide was embedded into the framework via in-situ synthesis method to form a composite structure of Mg-MOF-74@nGO. n was varied from 0.1 to 0.6 wt% of the weight of pristine material. The synthesized samples were examined under Powder X-Ray Diffraction analysis to affirm their crystalline structure. Further studies were conducted by indexing the lattice parameters of the hexagonal crystals. The volume of unit cell and Scherrer’s crystallite size were also determined to study the effect of GO loading amount on their grown dimensions. The results showed that the presence of GO in the range of 0.1-0.6 wt% did not influence the dimension of the crystal except a slight expansion in vertical direction with the increment of GO loading.

Single Step Process for Crystalline Ni-B Compounds

Crystalline Ni2B, Ni3B, and Ni4B3 are synthesized by a single-step method using autogenous pressure from the reaction of NaBH4 and Ni precursors. The effect of reaction temperature, pressure, time, and starting materials on the composition of synthesized products, particle morphologies, and magnetic properties is demonstrated. High yields of Ni2B (>98%) are achieved at 2.3–3.4 MPa and ~670 °C over five hours. Crystalline Ni3B or Ni4B3 form in conjunction with Ni2B at higher temperature or higher autogenous pressure in proportions influenced by the ratios of initial reactants. For the same starting ratios of reactants, a longer reaction time or higher pressure shifts equilibria to lower yields of Ni2B. Using this approach, yields of ~88% Ni4B3 (single phase orthorhombic) and ~72% Ni3B are obtained for conditions 1.9 MPa < Pmax < 4.9 MPa and 670 °C < Tmax < 725 °C. Gas-solid reaction is the dominant transformation mechanism that results in formation of Ni2B at lower temperatures than conventional solid-state methods.